14._The_Noble_Gases_v1.0

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化学浪漫文案英语高级句子

化学浪漫文案英语高级句子1. Chemistry is the perfect equation for our love story, a combination so potent that it ignites a spark in our hearts.2. In your eyes, I see a molecular reaction that takes my breath away and leaves me in awe of the miracle of chemistry.3. Our love is like a perfectly balanced chemical equation, with every element complementing and completing each other.4. Just like in chemistry, when our souls collide, the reaction is explosive and the bond unbreakable.5. Our love is the perfect chemistry experiment –a blend of passion, understanding, and endless discoveries.6. As the atoms align in the universe, so do our souls, entangled in a beautifully intricate chemical bond.7. Our love is akin to a delicate chemical equilibrium, where even the slightest touch can create a magnificent reaction.8. Like the periodic table, we are a unique combination of elements, fusing together to create something extraordinary.9. Just as molecules are bonded by shared electrons, we are connected by an unbreakable bond that defies the odds.10. Chemistry brought us together, but it's the undeniable chemistry between our souls that keeps us inseparable.11. Our love is a delicate mixture of elements, constantly evolving andtransforming into something more beautiful than ever before.12. Like the noble gases, our love is stable and resistant to outside forces,a testament to the strength of our connection.13. In the laboratory of love, you are the catalyst that speeds up the reactions of my heart and makes me fall deeper every day.14. Like the most exquisite chemical reaction, our love creates a symphony of emotions that leaves us breathless and yearning for more.15. Our love story is a masterpiece of molecular attraction, where the forces of chemistry combine to create a love that is both magical and unforgettable.。

新托福TPO22阅读原文及译文(三)

新托福TPO22阅读原文(三)：The Allende MeteoriteTPO22-3：The Allende MeteoriteSometime after midnight on February 8,1969, a large, bright meteor entered Earth's atmosphere and broke into thousands of pieces, plummeted to the ground, and scattered over an area 50 miles long and 10 miles wide in the state of Chihuahua in Mexico. The first meteorite from this fall was found in the village of Pueblito de Allende. Altogether, roughly two tons of meteorite fragments were recovered, all of which bear the name Allende for the location of the first discovery.Individual specimens of Allende are covered with a black, glassy crust that formed when their exteriors melted as they were slowed by Earth's atmosphere. When broken open, Allende stones are revealed to contain an assortment of small, distinctive objects, spherical or irregular in shape and embedded in a dark gray matrix (binding material), which were once constituents of the solar nebula—the interstellar cloud of gas and dust out of which our solar system was formed.The Allende meteorite is classified as a chondrite. Chondrites take their name from the Greek word chondros—meaning "seed"—an allusion to their appearance as rocks containing tiny seeds. These seeds are actually chondrules: millimeter-sized melted droplets of silicate material that were cooled into spheres of glass and crystal.A few chondrules contain grains that survived the melting event, so these enigmatic chondrules must have formed when compact masses of nebular dust were fused at high temperatures—approaching 1,700 degrees Celsius—and then cooled before these surviving grains could melt. Study of the textures of chondrules confirms that they cooled rather quickly, in times measured in minutes or hours, so the heating events that formed them must have been localized. It seems very unlikely that large portions of the nebula were heated to such extreme temperatures, and huge nebula areas could not possibly have lost heat so fast. Chondrules must have been melted in small pockets of the nebula that were able to lose heat rapidly. The origin of these peculiar glassy spheres remains an enigma.Equally perplexing constituents of Allende are the refractory inclusions: irregular white masses that tend to be larger than chondrules. They are composed of minerals uncommon on Earth, all rich in calcium, aluminum, and titanium, the most refractory (resistant to melting) of the major elements in the nebula. The same minerals that occur in refractory inclusions are believed to be the earliest-formed substances to have condensed out of the solar nebula. However, studies of the textures of inclusions reveal that the order in which the minerals appeared in the inclusions varies from inclusion to inclusion, and often does not match the theoretical condensation sequence for those metals.Chondrules and inclusions in Allende are held together by the chondrite matrix, a mixture of fine-grained, mostly silicate minerals that also includes grains of iron metal and iron sulfide. At one time it was thought that these matrix grains might be pristine nebular dust, the sort of stuff from which chondrules and inclusions were made. However, detailed studies of the chondrite matrix suggest that much of it, too, has been formed by condensation or melting in the nebula, although minute amounts of surviving interstellar dust are mixed with the processed materials.All these diverse constituents are aggregated together to form chondritic meteorites, like Allende, that have chemical compositions much like that of the Sun. To compare the compositions of a meteorite and the Sun, it is necessary that we use ratios of elements rather than simply the abundances of atoms. After all, the Sun has many more atoms of any element, say iron, than does a meteorite specimen, but the ratios of iron to silicon in the two kinds of matter might be comparable. The compositional similarity is striking. The major difference is that Allende is depleted in the most volatile elements, like hydrogen, carbon, oxygen, nitrogen, and the noble gases, relative to the Sun. These are the elements that tend to form gases even at very low temperatures. We might think of chondrites as samples of distilled Sun, a sort of solar sludge from which only gases have been removed. Since practically all the solar system's mass resides in the Sun, this similarity in chemistry means that chondrites have average solar system composition, except for the most volatile elements; theyare truly lumps of nebular matter, probably similar in composition to the matter from which planets were assembled.TPO22-3译文：阿伦德陨星在1969年2月8日子夜后的某一时刻，一颗巨大明亮的流星进入地球大气层，碎成无数的碎块，坠落到地面，散布在墨西哥奇瓦瓦州境内50英里长10英里宽的区域内。

化学专业英语词汇

1.TheIdeal-GasEquation理想气体状态方程2.Partial Pressures分压3.Real Gases:Deviation from IdealBehavior真实气体：对理想气体行为的偏离4.Thevande rWaals Equation范德华方程5.Systemand Surroundings系统与环境6.Stateand State Functions状态与状态函数7.Process过程8.Phase相9.The First Lawof Thermodynamics热力学第一定律10.Heatand Work热与功11.Endothermicand Exothermic Processes吸热与发热过程12.Enthalpiesof Reactions反应热13.Hess’s Law盖斯定律14.Enthalpiesof Formation生成焓15.Reaction Rates反应速率16.Reaction Order反应级数17.Rate Constants速率常数18.Activation Energy活化能19.The Arrhenius Equation阿累尼乌斯方程20.Reaction Mechanisms反应机理21.Homogeneous Catalysis均相催化剂22.Heterogeneous Catalysis非均相催化剂23.Enzymes酶24.The Equilibrium Constant平衡常数25.the Directionof Reaction反应方向26.L eChatelier’s Principle列·沙特列原理27.Effects of V olume,Pressure,Temperature Changesand Catalystsi.体积，压力，温度变化以及催化剂的影响28.Spontaneous Processes自发过程29.Entropy (StandardEntropy)熵（标准熵）30.The Second Law of Thermodynamics热力学第二定律31.EntropyChanges熵变32.StandardFree-EnergyChanges标准自由能变33.Acid-Bases酸碱34.The Dissociation of Water水离解35.The Protonin Water水合质子36.Thep H ScalespH值37.Bronsted-Lowry Acidsand Bases Bronsted-Lowry酸和碱38.Proton-Transfer Reactions质子转移反应39.Conjugate Acid-Base Pairs共轭酸碱对71.ThePauli Exclusion Principle泡林不相容原理72.Electron Configurations电子构型73.The PeriodicTable周期表74.Row行75.Group族76.Isotopes,Atomic Numbers,andMass Numbers同位素，原子数，质量数77.Periodic Properties o fthe Elements元素的周期律78.Radiu of Atoms原子半径79.Ionization Energy电离能80.Electronegativity电负性81.Effective Nuclear Charge有效核电荷82.Electron Affinities亲电性83.Metals金属84.Nonmetals非金属85.Valence Bond Theory价键理论86.Covalence Bond共价键87.Orbital Overlap轨道重叠88.Multiple Bonds重键89.Hybrid Orbital杂化轨道90.The VSEPR Model价层电子对互斥理论91.Molecular Geometries分子空间构型92.Molecular Orbital分子轨道93.Diatomic Molecules双原子分子94.Bond Length键长95.Bond Order键级96.Bond Angles键角97.Bond Enthalpies键能98.Bond Polarity键矩99.Dipole Moments偶极矩100.Polarity Molecules极性分子101.Polyatomic Molecules多原子分子102.Crystal Structure晶体结构130.Peroxidesand Superoxides过氧化物和超氧化物131.Hydroxides氢氧化物132.Salts盐133.p-BlockElementsp区元素134.Boron Group(Boron,Aluminium,Gallium,Indium,Thallium)硼族（硼，铝，镓，铟，铊）135.Borane硼烷136.Carbon Group(Carbon,Silicon,Germanium,Tin,Lead)碳族（碳，硅，锗，锡，铅）137.Graphite,Carbon Monoxide,Carbon Dioxide石墨，一氧化碳，二氧化碳138.CarbonicAcid,Carbonatesand Carbides碳酸，碳酸盐，碳化物139.Occurrenceand Preparation of Silicon硅的存在和制备140.Silicic Acid，Silicates硅酸，硅酸盐141.Nitrogen Group(Phosphorus,Arsenic,Antimony,andBismuth)氮族（磷，砷，锑，铋）142.Ammonia,NitricAcid,PhosphoricAcid氨，硝酸，磷酸143.Phosphorates,phosphorus Halides磷酸盐，卤化磷144.Oxygen Group(Oxygen,Sulfur,Selenium,andTellurium)氧族元素（氧，硫，硒，碲）145.Ozone,HydrogenPeroxide臭氧，过氧化氢146.Sulfides硫化物147.Halogens(Fluorine,Chlorine,Bromine,Iodine)卤素（氟，氯，溴，碘）148.Halides,Chloride卤化物，氯化物149.The Noble Gases稀有气体150.Noble-GasCompounds稀有气体化合物151.d-Blockelementsd区元素152.Transition Metals过渡金属153.Potassium Dichromate重铬酸钾154.Potassium Permanganate高锰酸钾155.Iron Copper ZincMercury铁，铜，锌，汞156.f-Block Elementsf区元素nthanides镧系元素158.Radioactivity放射性159.Nuclear Chemistry核化学160.Nuclear Fission核裂变161.Nuclea Fusion核聚变162.analyticalchemistry分析化学163.qualitativeanalysis定性分析186.deviation偏差187.precision精密度188.relativestandarddeviation相对标准偏差（RSD）189.coefficientvariation变异系数（CV）190.confidencelevel置信水平191.confidenceinterval置信区间192.significanttest显著性检验193.significantfigure有效数字194.standardsolution标准溶液195.titration滴定196.stoichiometricpoint化学计量点197.endpoint滴定终点198.titrationerror滴定误差199.primarystandard基准物质200.amountofsubstance物质的量201.standardization标定202.chemicalreaction化学反应203.concentration浓度204.chemicalequilibrium化学平衡205.titer滴定度206.generalequationforachemicalreaction化学反应的通式207.protontheoryofacid-base酸碱质子理论208.acid-basetitration酸碱滴定法209.dissociationconstant解离常数210.conjugateacid-basepair共轭酸碱对211.aceticacid乙酸212.hydroniumion水合氢离子213.electrolyte电解质214.ion-productconstantofwater水的离子积215.ionization电离216.protoncondition质子平衡217.zerolevel零水准218.buffersolution缓冲溶液219.methylorange甲基橙220.acid-baseindicator酸碱指示剂221.phenolphthalein酚酞251.cerimetry铈量法252.redoxindicator氧化还原指示253.oxygenconsuming耗氧量（OC）254.chemicaloxygendemanded化学需氧量(COD) 255.dissolvedoxygen溶解氧(DO)256.precipitation沉淀反应257.argentimetry银量法258.heterogeneousequilibriumofions多相离子平衡259.aging陈化260.postprecipitation继沉淀261.coprecipitation共沉淀262.ignition灼烧263.fitration过滤264.decantation倾泻法265.chemicalfactor化学因数266.spectrophotometry分光光度法267.colorimetry比色分析268.transmittance透光率269.absorptivity吸光率270.calibrationcurve校正曲线271.standardcurve标准曲线272.monochromator单色器273.source光源274.wavelengthdispersion色散275.absorptioncell吸收池276.detector检测系统277.bathochromicshift红移278.Molarabsorptivity摩尔吸光系数279.hypochromicshift紫移280.acetylene乙炔281.ethylene乙烯282.acetylatingagent乙酰化剂283.aceticacid乙酸284.adiethylether乙醚285.ethylalcohol乙醇286.acetaldehtde乙醛287.β-dicarbontlcompoundβ–二羰基化合物288.bimolecularelimination双分子消除反应289.bimolecularnucleophilicsubstitution双分子亲核取代反应322.Michaelreacton麦克尔反应323.halogenatedhydrocarbon卤代烃324.haloformreaction卤仿反应325.systematicnomenclatur系统命名法e326.Newmanprojection纽曼投影式327.aromaticcompound芳香族化合物328.aromaticcharacter芳香性r329.Claisencondensationreaction克莱森酯缩合反应330.Claisenrearrangement克莱森重排331.Diels-Alderreation狄尔斯-阿尔得反应332.Clemmensenreduction克莱门森还原333.Cannizzaroreaction坎尼扎罗反应334.positionalisomers位置异构体335.unimoleculareliminationreaction单分子消除反应336.unimolecularnucleophilicsubstitution单分子亲核取代反应337.benzene苯338.functionalgrou官能团p339.configuration构型340.conformation构象341.confomationalisome构象异构体342.electrophilicaddition亲电加成343.electrophilicreagent亲电试剂344.nucleophilicaddition亲核加成345.nucleophilicreagent亲核试剂346.nucleophilicsubstitutionreaction亲核取代反应347.activeintermediate活性中间体348.Saytzeffrule查依采夫规则349.cis-transisomerism顺反异构350.inductiveeffect诱导效应t351.Fehling’sreagent费林试剂352.phasetransfercatalysis相转移催化作用353.aliphaticcompound脂肪族化合物354.eliminationreaction消除反应355.Grignardreagent格利雅试剂灭滴灵Metronidazole柠檬酸CitricAcid硝酸钙calciumnitrate癸二酸SebacicAcid冰醋酸glacialaceticacid维生素C磷酸镁MagnesiumAscorbylPhosphate 对苯二酚Hydroquinone环丙沙星盐酸CIPROFLOXACINHCL氢氧化钠SodiumHydroxide吗菌灵醋酸盐dodemorphacetate烯酰吗啉dimethomorph百菌清Chlorothalonil尼索朗hexythiazox哒螨灵pyridaben葡萄糖酸-δ-内酯gluconodeltalactone硫酸粘杆菌素colistinesulfate恩诺沙星EnrofloxacinBase土霉素盐酸OxyTetraCyclineHCl黄磷YellowPhosphorus索布瑞醇Sobrerol焦棓酸PYROGALLOL硫乙醇酸THIOGLYCOLLICACID茴香硫醚THIOANISOLE1-溴-3-氯丙烷1-BROMO-3-CHLOROPROPANE 氟苯FLUOROBENZEN叔丁基胺tert-butylamine丙烯酸树脂Acrylicresin维生素B6VITAMINB6磺胺胍Sulfaguanidine松香树脂GumRosin苯甲酸钠SODIUMBENZOATE双氧水HydrogenPeroxide6-氨基己烷-1-醇6-aminohexan-1-ol邻苯二甲酸酐PhthalicAnhydride2,3-二氨基甲苯2,3-diaminotoluene吲哚indole2-甲基吲哚2-methylindole三苯基硼triphenylborane松油精Dipentine十六烷醇CetylAlcohol呋喃-2-硼酸FURAN-2-BORONICACID莫匹罗星Mupirocin高锰酸钾PotassiumPermanganate噻苯咪唑Thiabendazole42-amino-2-(hydroxymethyl)-1,3,propanediol二环戊二烯Dicyclopentadiene(DCPD)金红石型氧化钛TitaniumDioxide(Rutile)Topgrade硼酸boricacid氧化铅LeadOxide邻苯二甲酸酐PhthalicAnhydride叔丁基锡烷tributylstannane碳黑CarbonBlackElftex430碳黑CarbonBlackN300碳黑CarbonBlackN-326磷酸PHOSPHORICACID硝酸铅LEADNITRATE硬脂酸铅LEADSTEARA TE次硫酸钠SodiumHydrosulfite磷酸二氢铵AmmoniumDihydrogenPhosphate 水合肼HydrazineHydrate6三聚磷酸钠SodiumTripolyphosphate氧化铁黄ironoxideyellow氧化铁红ironoxidered1,1,1-三氯乙烷1,1,1-TrichloroEthane氯化铵AmmoniumChloride苯酚PHENOL甲氧苄氨嘧啶TRIMETHOPRIM磷酸三钙tricalciumphosphate酒石酸苯甲曲秦PhendimetrazineTartrate碳酸氢钠sodiumbicarbonate氯四环素盐酸ChlortetracyclineHCl三水合氨卡青霉素AmpicillinTrihydratemicronized 山梨糖醇SorbitolPowder一水葡萄糖DextroseMonohydrate碳化钙calciumcarbide柚皮甙Naringin叶绿素铜钠盐sodiumcopper苏打灰sodaash酒石酸盐tartrate鉻酸銨AMMONIUMCHROMATE苦味酸PICRICACID甲酸铵AMMONIUMFORMATE7聚丙烯薄膜PPSHEETFOROPPTAPE氨基乙酸Glycine氨比西林AMPICILINE土霉素盐酸OxytetracyclineHCL6-溴-2-羟基萘6-Bromo-2-hydroxynaphthalene2，6-二甲氧基萘2,6-Dimethoxynaphthalene2，6-二羟基萘2,6-Dihydroxynaphthalene6-甲氧基-2-羟基萘6-Methoxy-2-hydroxynaphthalene 2-叔丁基-4-甲基苯酚2-Tertiary-butyl-4-methylphenol 炉甘石Calamine5-溴-2-甲基嘧啶5-Bromo-2-methylpyridine氯化镁MagnesiumChloride。

美国普通化学笔记5

ChemistryChapter 8∙In 1864, English chemists john newlands noticed that when the known elements were arranged in order of atomic mass, every eighth element hadsimilar properties. Newlands referred to this peculiar relationship as thelaw of octaves. Howe ver, this “law” turned out to be inadequate forelements beyond calcium, and newland’s work was not accepted by thescientific community.∙Representative elements are the elements in groups 1A through 7A, all of which have incompletely filled s or p subshells of the highest principalquantum number. With the exception of helium, the noble gases (thegroup 8A elements) all have a completely filled p subshell. The transitionmetals are the elements in groups 1B and 3B through 8B, which haveincompletely filled d subshells or readily produce cations withincompletely filled d subshells (these metals are sometimes referred to asthe d-blok transition elements). The group 2B elements are Zn, Cd, andHg, which are neither representative elements nor transition metals. Thelanthanides and actinides are sometimes called f-block transition elementsbecause they have incompletely filled f subshells∙The outer electrons of an atom, which are those involved in chemical bonding are often called the valence electrons. Having the same number ofvalence electrons accounts for similarities in chemical behavior among theelements within each of these groups.∙Ions, or atoms and ions, that have the same number of electrons and hence the same ground-state electron configuration are said to be isoelectronic.∙Atomic radius of a metal is one-half the distance between the two-nuclei in two adjacent atoms. For elements that exist as diatomic molecules, theatomic radius is one-half the distance between the nuclei of the two atomsin a particular molecule.∙When looking at a periodic table:o The elements are increasing as in atomic radius as you go fromright to left, and from up to down. ****∙Ionic radius is the radius of a cation or an anion. Ionic radius affects the physical and chemical properties of an ionic compound.∙When a neutral atom is converted to an ion, we expect a change in size. If the atoms forms an anion, its size increases, because the nuclear chargeremains the same but the repulsion resulting from the additional electronenlarges the domain of the electron cloud. On the other hand, a cation issmaller than the neutral atom, because removing one or more electronsreduces electron-electron repulsion but the nuclear charge remains thesame, so the electron cloud shrinks.∙Focusing on isoelectronic cations, we see that the radii of tripostive ions (that is, ions that bear three positive charges) are smaller than those ofdipositive ions (that is, ions that bear two positive charges) which in turnare smaller than unipositve ions (that is, ions that bear one positive charge).∙Ionization energy – is the minimum energy required to remove an electron from a gaseous atom in its ground state. The magnitude of ionizationenergy is a measure of the effort required to force an atom to give up anelectron, or of how “tightly” the electron is held in the atom., the higherthe ionization energy the more difficult it is to remove the electron.∙For a many-electron atom, the amount of energy required to remove the first electron, from the atom in its ground state:o Energy + X(g) -> X+(g) + e-o Is called the first ionization energy (I1). In this equation Xrepresent a gaseous atom of any element and e- is an electron.Unlike an atom in the condensed liquid and solid phases, an atomis the gaseous phase is virtually uninfluenced by its neighbors.o Energy + X+(g) -> X2+(g) + e- Second ionizationo Energy + X2+(g) -> X3+(g) + e- Third Ionization∙When a electron is removed from a neutral atom, the repulsion among the remains electrons decreases. Because the nuclear charge remains constant,more energy is needed to remove another electron from the positivelycharged ions. Thus for the same element ionization energies alwaysincrease in this order:o I1<I2<I3<….∙Another property that greatly influences the chemical behavior of atoms is their ability to accept one or more electrons. This ability is called electronaffinity, which is the negative of the energy change that occurs when anelectron is accepted by an atom of an element in the gaseous stateo X(g) + e- -> X-(g) deltaH = -XXXkJ▪If delta h has a positive value (ie. 390 kj/mol) means thatthe process is exothermic▪If delta h has a negative value, that means that the processis endothermic∙Another trend in chemical behavior of the representative elements is the diagonal relationship. Diagonal relationship refers to similarities that existbetween pairs of elements in different groups and period of the periodictable. Specifically the first three members of the second period (Li, Be andB) exhibit many similarities to the elements located diagonally belowthem in the periodic table.If you would like to further understand this chapter, I suggested reading the summary. Or if you would like to learn more about the individual group elements, then I suggest reading the last few pages of this chapter.Chapter 9∙Lewis dot symbol – consists of the symbol of an element and one dot for each valence electron in an atom of the element.∙Covalent bond – a bond in which two electrons are shared by two atoms.Covalent compounds are compounds that contain only covalent bonds.∙Lone pairs – pairs of valence electrons that are not involved in covalent bond formation (ie. F2)∙Lewis structures is a representation of covalent bonding in which shared electron pairs are shown either as lines or as pairs of dots between two atoms, and lone pairs are shown as pairs of dots on individual atoms. Only valence electrons are shown in a Lewis structure.∙Octet rule – an atom other than hydrogen tends to from bonds until it is surrounded by eight valence electrons. In other words, a covalent b ond forms when there are not enough electrons for each individual atom tohave a complete octet. By sharing electrons in a covalent bond, theindividual atoms can complete their octets. The requirement for hydrogen is that it attains the electron configuration of helium, or a total of twoelectrons.o The octet rule works mainly for elements in the second period of the periodic table.∙Atoms can form different types of covalent bonds. In a single bond – two atoms are held together by one electron pair. Many compounds are held together by multiple bonds, that is, bonds formed when two atoms shre two or more pairs of electrons. If two atoms share two pairs of electrons, the covalent bond is called a double bond.∙ A triple bond arises when two atoms share three pairs of electrons, (N2) ∙Bond length – is defined as the distance between the nuclei of two covalently bonded atoms in a molecule.∙The bond HF is called a polar covalent bond, or simply a polar bond, because the electrons spend more time in the vicinity of one atom than the other. The HF bond and other polar bonds can be though of as beingintermediate between a (nonpolar) covalent bond, in which the sharing of electrons is exactly equal, and an ionic bond, in which the transfer of the electron(s) is nearly complete.∙ A property that helps us distinguish a nonpolar covalent bond from a polar covalent bond is electronegativity, the ability of an atom to attract toward itself the electrons in a chemical bond. Elements with highelectronegativity have a greater tendency to attract electrons than doelements with low electronegativity.o Electronegativity is related to electron affinity and ionization energy.o Electronegativity is a relative concept, mea ign tha t an element’s ectronegativity can be measured only in relation theelectronegativity of other elements.o Linus Pauling devised a method for calculating relativeelectronegativities of most elements.∙There is no sharp distinction between a polar bond and an ionic bond, but the following rule is helpful in distinguishing between them. An ionicbond forms when the electronegativity difference between the twobonding atoms is 2.0 more. This rule applies to most but not all ioniccompounds. Sometimes chemists use the quantity percent ionic characterto describe the nature of a bond. A purely ionic bond would have 100percent ionic character, although no such bond is known, whereas anonpolar or purely covalent bond has 0 percent ionic character.∙Electronegativity and electron affinity are related but different concepts.Both indicate the tendency of an atom to attract electrons. However,electron affinity refers to an isolated atom’s attraction for an additionalelectron, whereas electronegativity signifies the ability of an atom in achemical bond (with another atom) to attract the shared electron.Furthermore, the electron affinity is an experimentally measurablequantity, whereas electronegativity is an estimated number that cannot be measured.∙An atom’s formal charge is the electrical charge difference between the valence electrons in an isolated atom and the number of electrons assigned to an atom in a lewis structure.∙To assign the number of electrons on an atom in a lewis structure, we proceed as:o All the ato m’s nonbonding electrons are assigned to the atomo We break the bond(s) between the atom and other atom(s) and assign half of the bonding electrons to the atom∙When you write formal charges, these rules are helpful:o For molecules, the sum of the formal charges must add up to zero because they are electrically neutral species.o For cations, the sum of the formal charges must equal the positive chargeo For anions, the sum of the formal charges must equal the negative charge∙Keep in mind, that formal charges do not represent actual charge separation within the molecule.∙Resonance structure – one of two or more lewis structures for a single molecule that cannot be represented accurately by only one lewis structure.The double-headed arrow indicates that the structures shown areresonance structures.∙The term resonance itself means the use of two or more lewis structures to represent a particular molecule.∙Exceptions to the octet rule:o The incomplete octet:▪In some compounds the number of electrons surround thecentral atom in a stable molecule is fewer than eight.▪Elements in group 3A, particularly boron and aluminum,also tend to form compounds in which they are surroundedby fewer than eight electrons.∙ A resonance structure with a double bond betweenB and F can be drawn that satisfies the octet rule forB.▪The B-N bond is different from the covalent bondsdiscussed so far in the sense that both electrons arecontributed by the N atom. A covalent bond in which oneof the atoms donated both electrons is called a coordinatecovalent bond. Although the properties of a coordinatecovalent bond do not differ from those of a normal covalentbond (because all electrons are alike no matter what theirsource), the distinction is useful for keeping tack of valenceelectrons and assigning formal charges)o Odd-Electron Molecules▪Some molecules contain an odd number of electrons.Among them are nitric oxide (NO) and nitrogen dioxide(NO2)▪Because we need an even number of electrons for completepairing (to reach eight) the octet rule clearly cannot besatisfied for all the atoms in any molecule that has an oddnumber of electronso The expanded octet:▪In a number of compounds there are more than eightvalence electrons around an atom. These expanded octetsare needed only for atoms of elements in and beyond thethird period of the periodic table.∙ A measure of the stability of a molecule is its bond energy, which is the enthalpy change required to break a particular bond in 1 mole of gaseousmolecules. (bond energies in solids and liquids are affected byneighboring molecules.)∙In many cases, it is possible to predict the approximate enthalpy ofreaction by using the average bond energies. Because energy is alwaysrequired to break chemical bonds and chemical bond formation is alwaysaccompanied by a release of energy, we can estimate the enthalpy of areaction by counting the total number of bonds broken and formed in thereaction and recording all the corresponding energy changes. The enthalpyof reaction in the gas phase is given by:o deltaH o = sigma(BE(reactants)) – sigma(BE(products))o where be stands for average bond energy and sigma is thesummation signTo further understand Bond energies, and Lewis dot structures and resonance I suggest taking a deeper look into the textbook.。

小学上册第九次英语第6单元测验卷

小学上册英语第6单元测验卷英语试题一、综合题(本题有100小题，每小题1分，共100分.每小题不选、错误，均不给分)1.What is the largest planet in our solar system?A. EarthB. MarsC. JupiterD. Saturn答案:C2.What do you call the person who studies history?A. HistorianB. ScientistC. BiologistD. Chemist3.Which animal is considered a reptile?A. FrogB. LizardC. SalmonD. Sparrow4.My _____ (外婆) is a wonderful cook.5.The invention of ________ has reshaped modern communication.6.The __________ is a geographic area known for its mountains.7.The ________ is very cheerful.8.What do we call a person who plays sports?A. AthleteB. CoachC. RefereeD. Fan9.The rabbit hops around the ________.10.What do you call the science of classifying living things?A. TaxonomyB. AnatomyC. EcologyD. PhysiologyA11.What is the term for a large group of stars in the universe?A. GalaxyB. ClusterC. Solar SystemD. ConstellationA12.The boiling point of water is __________ degrees Fahrenheit.13. A ________ (生态恢复) can bring back plants.14.We are going to ___ a concert. (attend)15.The chemical symbol for chromium is __________.16.What is the main ingredient in pesto?A. TomatoB. BasilC. GarlicD. CheeseB17.What is 5 x 2?A. 7B. 8C. 10D. 12C18.The _____ (小羊) bleats when it is hungry.19.The ______ (小鸟) chirps sweetly in the trees.20. A lion is a type of ______.21.My sister loves to ________.22.The ________ was a significant period in the evolution of human rights.23.continent) of Australia is both a country and a landmass. The ____ets have a bright tail that points away from the _______.25.What is the process of water turning into vapor called?A. CondensationB. EvaporationC. PrecipitationD. SublimationB26. A chemical reaction can change the physical ______.27.What do we call a baby cow?A. CalfB. KidC. LambD. FoalA28.The _______ (The Ottoman Empire) was a powerful empire that lasted for centuries.29.Which instrument has strings and is played with a bow?A. FluteB. GuitarC. ViolinD. PianoC Violin30.What is the name of the famous dessert made of cream and fruit?A. CakeB. Ice creamC. TartD. MousseD31.The _______ (鲸鱼) sprays water from its blowhole.32.The ancient Egyptians worshiped _______. (太阳神)33.The chemical symbol for roentgenium is ______.34.What is the name of the famous scientist who developed the theory of evolution?A. Charles DarwinB. Albert EinsteinC. Isaac NewtonD. Galileo Galilei35.The __________ was a significant period of change in Europe. (文艺复兴)36.What is the capital of the Bahamas?A. NassauB. FreeportC. EleutheraD. Long IslandA Nassau37.What do you call a piece of furniture for sitting?A. TableB. ChairC. BedD. ShelfB38. A _______ can grow in different climates.39.What do you call a collection of books?A. LibraryB. MuseumC. GalleryD. Shop40.I have _____ (three/four) apples in my bag.41.The kitten loves to chase its _______ (尾巴).42. A ______ (温带) climate supports many types of flora.43.We write with a ___. (pen)44. A curious ___ (小鸽子) pecks at crumbs.45. A ________ (植物观察) can inspire stories.46.When it rains, I wear my ________ (雨衣) and jump in the ________ (水坑).47.What is the name of the famous statue found in New York Harbor?A. DavidB. Christ the RedeemerC. Statue of LibertyD. Venus de MiloC48.The __________ (花香) fills the air in spring.49.Which animal is known for building dams?A. BeaverB. FoxC. RabbitD. Owl50. A dog wags its _______ (尾巴) when happy.51.An electrolyte is a substance that conducts electricity when _____.52.What is the primary color made by mixing blue and yellow?A. GreenB. OrangeC. PurpleD. Brown53.The ______ (植物的生存) depends on various factors.54.The __________ (历史的反思) helps societies grow.55.The flowers are ___. (colorful)56.My brother is interested in ____ (mathematics).57.I enjoy ______ (与家人一起) playing sports.58.The ______ (海豚) is known for its intelligence.59.I have a __________ who lives next door. (邻居)60.The __________ is a major mountain range in North America. (落基山脉)61.I enjoy building things with my __________ (玩具名).62.I have fun playing sports with my ____.63.I like to play ___ (cards).64.What do you call a book of maps?A. AtlasB. DictionaryC. EncyclopediaD. NovelA65.The law of definite proportions states that a given chemical compound always contains its component elements in fixed _______.66.My dad teaches me to be __________ (负责任的) in my actions.67.We visit the ______ (博物馆) for field trips.68.The ancient Egyptians constructed ______ (神庙) for their gods.69.I want to learn more about ______ (植物) and how they grow. They are very ______ (重要).70.environmental monitoring) tracks ecosystem health. The ____71.The __________ (历史成就) can be celebrated.72.What do we call a young lion?A. CubB. PuppyC. KittenD. Calf73.My favorite ________ (玩具车) is red and can go very fast.74.My hamster has a _______ (舒适的) home.75.Mars is often called the ______ planet.76. A chemical property describes how a substance reacts with ______.77.What is the main language spoken in Spain?A. FrenchB. ItalianC. SpanishD. PortugueseC78.I like to ride my _____ (horse/bike) in the park.79.The process of breaking down food in our bodies is called ______.80.Which animal is known for its intelligence and ability to use tools?A. DolphinB. HorseC. CatD. FishA81.I have a toy _______ that can build things.82. A _____ (植物活动) can raise awareness about conservation.83.What is the smallest unit of life?A. CellB. TissueC. OrganD. Organism84.My sister has a __________ (好心) nature.85.The chemical formula for potassium phosphate is ______.86.The ______ helps regulate the body's temperature.87.My favorite _________ (玩具) can spin and dance.88.What do we call a person who studies the history of science?A. Science HistorianB. SociologistC. AnthropologistD. PhilosopherA89.My ___ (小猫) purrs when I pet it.90.My brother is really into _______ (运动). 他希望能 _______ (动词).91.What is the capital of the Philippines?A. ManilaB. CebuC. DavaoD. Iloilo92.The __________ (历史的启发) ignites passion.93.The stars are ________ (闪闪发光).94.I _____ (love/hate) homework.95.In _____ (挪威), you can find beautiful fjords.96.What do you call a young deer?A. CalfB. KidC. FawnD. LambC97. A solid has a __________ (固定的) shape and volume.98.The country famous for its classical music is ________ (奥地利).99.What is the name of Saturn's largest moon?A. TitanB. EnceladusC. RheaD. Iapetus100.The main component of natural gas is _______.。

常见化学专业词汇英文翻译

常见化学专业词汇英文翻译1. The Ideal-Gas Equation 理想气体状态方程2. Partial Pressures 分压3. Real Gases: Deviation from Ideal Behavior 真实气体：对理想气体行为的偏离4. The van der Waals Equation 范德华方程5. System and Surroundings 系统与环境6. State and State Functions 状态与状态函数7. Process 过程8. Phase 相9. The First Law of Thermodynamics 热力学第一定律10. Heat and Work 热与功11. Endothermic and Exothermic Processes 吸热与发热过程12. Enthalpies of Reactions 反应热13. Hess’s Law 盖斯定律14. Enthalpies of Formation 生成焓15. Reaction Rates 反应速率16. Reaction Order 反应级数17. Rate Constants 速率常数18. Activation Energy 活化能19. The Arrhenius Equation 阿累尼乌斯方程20. Reaction Mechanisms 反应机理21. Homogeneous Catalysis 均相催化剂22. Heterogeneous Catalysis 非均相催化剂23. Enzymes 酶24. The Equilibrium Constant 平衡常数25. the Direction of Reaction 反应方向26. Le Chatelier’s Principle 列·沙特列原理27. Effects of Volume, Pressure, Temperature Changes and Catalystsi. 体积，压力，温度变化以及催化剂的影响28. Spontaneous Processes 自发过程29. Entropy (Standard Entropy) 熵（标准熵）30. The Second Law of Thermodynamics 热力学第二定律31. Entropy Changes 熵变32. Standard Free-Energy Changes 标准自由能变33. Acid-Bases 酸碱34. The Dissociation of Water 水离解35. The Proton in Water 水合质子36. The pH Scales pH值37. Bronsted-Lowry Acids and Bases Bronsted-Lowry 酸和碱38. Proton-Transfer Reactions 质子转移反应39. Conjugate Acid-Base Pairs 共轭酸碱对40. Relative Strength of Acids and Bases 酸碱的相对强度41. Lewis Acids and Bases 路易斯酸碱42. Hydrolysis of Metal Ions 金属离子的水解43. Buffer Solutions 缓冲溶液44. The Common-Ion Effects 同离子效应45. Buffer Capacity 缓冲容量46. Formation of Complex Ions 配离子的形成47. Solubility 溶解度48. The Solubility-Product Constant Ksp 溶度积常数49. Precipitation and separation of Ions 离子的沉淀与分离50. Selective Precipitation of Ions 离子的选择沉淀51. Oxidation-Reduction Reactions 氧化还原反应52. Oxidation Number 氧化数53. Balancing Oxidation-Reduction Equations 氧化还原反应方程的配平54. Half-Reaction 半反应55. Galvani Cell 原电池56. Voltaic Cell 伏特电池57. Cell EMF 电池电动势58. Standard Electrode Potentials 标准电极电势59. Oxidizing and Reducing Agents 氧化剂和还原剂60. The Nernst Equation 能斯特方程61. Electrolysis 电解62. The Wave Behavior of Electrons 电子的波动性63. Bohr’s Model of The Hydrogen Atom 氢原子的波尔模型64. Line Spectra 线光谱65. Quantum Numbers 量子数66. Electron Spin 电子自旋67. Atomic Orbital 原子轨道68. The s (p, d, f) Orbital s（p，d，f）轨道69. Many-Electron Atoms 多电子原子70. Energies of Orbital 轨道能量71. The Pauli Exclusion Principle 泡林不相容原理72. Electron Configurations 电子构型73. The Periodic Table 周期表74. Row 行75. Group 族76. Isotopes, Atomic Numbers, and Mass Numbers 同位素，原子数，质量数77. Periodic Properties of the Elements 元素的周期律78. Radius of Atoms 原子半径79. Ionization Energy 电离能80. Electronegativity 电负性81. Effective Nuclear Charge 有效核电荷82. Electron Affinities 亲电性83. Metals 金属84. Nonmetals 非金属85. Valence Bond Theory 价键理论86. Covalence Bond 共价键87. Orbital Overlap 轨道重叠88. Multiple Bonds 重键89. Hybrid Orbital 杂化轨道90. The VSEPR Model 价层电子对互斥理论91. Molecular Geometries 分子空间构型92. Molecular Orbital 分子轨道93. Diatomic Molecules 双原子分子94. Bond Length 键长95. Bond Order 键级96. Bond Angles 键角97. Bond Enthalpies 键能98. Bond Polarity 键矩99. Dipole Moments 偶极矩100. Polarity Molecules 极性分子101. Polyatomic Molecules 多原子分子102. Crystal Structure 晶体结构103. Non-Crystal 非晶体104. Close Packing of Spheres 球密堆积105. Metallic Solids 金属晶体106. Metallic Bond 金属键107. Alloys 合金108. Ionic Solids 离子晶体109. Ion-Dipole Forces 离子偶极力110. Molecular Forces 分子间力111. Intermolecular Forces 分子间作用力112. Hydrogen Bonding 氢键113. Covalent-Network Solids 原子晶体114. Compounds 化合物115. The Nomenclature, Composition and Structure of Complexes 配合物的命名，组成和结构116. Charges, Coordination Numbers, and Geometries 电荷数、配位数、及几何构型117. Chelates 螯合物118. Isomerism 异构现象119. Structural Isomerism 结构异构120. Stereoisomerism 立体异构121. Magnetism 磁性122. Electron Configurations in Octahedral Complexes 八面体构型配合物的电子分布123. Tetrahedral and Square-planar Complexes 四面体和平面四边形配合物124. General Characteristics 共性125. s-Block Elements s区元素126. Alkali Metals 碱金属127. Alkaline Earth Metals 碱土金属128. Hydrides 氢化物129. Oxides 氧化物130. Peroxides and Superoxides 过氧化物和超氧化物131. Hydroxides 氢氧化物132. Salts 盐133. p-Block Elements p区元素134. Boron Group (Boron, Aluminium, Gallium, Indium, Thallium) 硼族（硼，铝，镓，铟，铊）135. Borane 硼烷136. Carbon Group (Carbon, Silicon, Germanium, Tin, Lead) 碳族（碳，硅，锗，锡，铅）137. Graphite, Carbon Monoxide, Carbon Dioxide 石墨，一氧化碳，二氧化碳138. Carbonic Acid, Carbonates and Carbides 碳酸，碳酸盐，碳化物139. Occurrence and Preparation of Silicon 硅的存在和制备140. Silicic Acid，Silicates 硅酸，硅酸盐141. Nitrogen Group (Phosphorus, Arsenic, Antimony, and Bismuth) 氮族（磷，砷，锑，铋）142. Ammonia, Nitric Acid, Phosphoric Acid 氨，硝酸，磷酸143. Phosphorates, phosphorus Halides 磷酸盐，卤化磷144. Oxygen Group (Oxygen, Sulfur, Selenium, and Tellurium) 氧族元素（氧，硫，硒，碲）145. Ozone, Hydrogen Peroxide 臭氧，过氧化氢146. Sulfides 硫化物147. Halogens (Fluorine, Chlorine, Bromine, Iodine) 卤素（氟，氯，溴，碘）148. Halides, Chloride 卤化物，氯化物149. The Noble Gases 稀有气体150. Noble-Gas Compounds 稀有气体化合物151. d-Block elements d区元素152. Transition Metals 过渡金属153. Potassium Dichromate 重铬酸钾154. Potassium Permanganate 高锰酸钾155. Iron Copper Zinc Mercury 铁，铜，锌，汞156. f-Block Elements f区元素157. Lanthanides 镧系元素158. Radioactivity 放射性159. Nuclear Chemistry 核化学160. Nuclear Fission 核裂变161. Nuclear Fusion 核聚变162. analytical chemistry 分析化学163. qualitative analysis 定性分析164. quantitative analysis 定量分析165. chemical analysis 化学分析166. instrumental analys is 仪器分析167. titrimetry 滴定分析168. gravimetric analysis 重量分析法169. regent 试剂170. chromatographic analysis 色谱分析171. product 产物172. electrochemical analysis 电化学分析173. on-line analysis 在线分析174. macro analysis 常量分析175. characteristic 表征176. micro analysis 微量分析177. deformation analysis 形态分析178. semimicro analysis 半微量分析179. systematical error 系统误差180. routine analys is 常规分析181. random error 偶然误差182. arbitration analysis 仲裁分析183. gross error 过失误差184. normal distribution 正态分布185. accuracy 准确度186. deviation偏差187. precision 精密度188. relative standard deviation 相对标准偏差（RSD）189. coefficient variation 变异系数（CV）190. confidence level 置信水平191. confidence interval 置信区间192. significant test 显著性检验193. significant figure 有效数字194. standard solution 标准溶液195. titration 滴定196. stoichiometric point 化学计量点197. end point滴定终点198. titration error 滴定误差199. primary standard 基准物质200. amount of substance 物质的量201. standardization 标定202. chemical reaction 化学反应203. concentration浓度204. chemical equilibrium 化学平衡205. titer 滴定度206. general equation for a chemical reaction化学反应的通式207. proton theory of acid-base 酸碱质子理论208. acid-base titration 酸碱滴定法209. dissociation constant 解离常数210. conjugate acid-base pair 共轭酸碱对211. acetic acid 乙酸212. hydronium ion水合氢离子213. electrolyte 电解质214. ion-product constant of water 水的离子积215. ionization 电离216. proton condition 质子平衡217. zero level零水准218. buffer solution缓冲溶液219. methyl orange 甲基橙220. acid-base indicator 酸碱指示剂221. phenolphthalein 酚酞222. coordination compound 配位化合物223. center ion 中心离子224. cumulative stability constant 累积稳定常数225. alpha coefficient 酸效应系数226. overall stability constant 总稳定常数227. ligand 配位体228. ethylenediamine tetraacetic acid 乙二胺四乙酸229. side reaction coefficient 副反应系数230. coordination atom 配位原子231. coordination number 配位数232. lone pair electron 孤对电子233. chelate compound 螯合物234. metal indicator 金属指示剂235. chelating agent 螯合剂236. masking 掩蔽237. demasking 解蔽238. electron 电子239. catalysis 催化240. oxidation氧化241. catalyst 催化剂242. reduction 还原243. catalytic reaction 催化反应244. reaction rate 反应速率245. electrode potential 电极电势246. activation energy 反应的活化能247. redox couple 氧化还原电对248. potassium permanganate 高锰酸钾249. iodimetry碘量法250. potassium dichromate 重铬酸钾251. cerimetry 铈量法252. redox indicator 氧化还原指示253. oxygen consuming 耗氧量（OC）254. chemical oxygen demanded 化学需氧量(COD) 255. dissolved oxygen 溶解氧(DO)256. precipitation 沉淀反应257. argentimetry 银量法258. heterogeneous equilibrium of ions 多相离子平衡259. aging 陈化260. postprecipitation 继沉淀261. coprecipitation 共沉淀262. ignition 灼烧263. fitration 过滤264. decantation 倾泻法265. chemical factor 化学因数266. spectrophotometry 分光光度法267. colorimetry 比色分析268. transmittance 透光率269. absorptivity 吸光率270. calibration curve 校正曲线271. standard curve 标准曲线272. monochromator 单色器273. source 光源274. wavelength dispersion 色散275. absorption cell吸收池276. detector 检测系统277. bathochromic shift 红移278. Molar absorptivity 摩尔吸光系数279. hypochromic shift 紫移280. acetylene 乙炔281. ethylene 乙烯282. acetylating agent 乙酰化剂283. acetic acid 乙酸284. adiethyl ether 乙醚285. ethyl alcohol 乙醇286. acetaldehtde 乙醛287. β-dicarbontl compound β–二羰基化合物288. bimolecular elimination 双分子消除反应289. bimolecular nucleophilic substitution 双分子亲核取代反应290. open chain compound 开链族化合物291. molecular orbital theory 分子轨道理论292. chiral molecule 手性分子293. tautomerism 互变异构现象294. reaction mechanism 反应历程295. chemical shift 化学位移296. Walden inversio 瓦尔登反转n297. Enantiomorph 对映体298. addition rea ction 加成反应299. dextro- 右旋300. levo- 左旋301. stereochemistry 立体化学302. stereo isomer 立体异构体303. Lucas reagent 卢卡斯试剂304. covalent bond 共价键305. conjugated diene 共轭二烯烃306. conjugated double bond 共轭双键307. conjugated system 共轭体系308. conjugated effect 共轭效应309. isomer 同分异构体310. isomerism 同分异构现象311. organic chemistry 有机化学312. hybridization 杂化313. hybrid orbital 杂化轨道314. heterocyclic compound 杂环化合物315. peroxide effect 过氧化物效应t316. valence bond theory 价键理论317. sequence rule 次序规则318. electron-attracting grou p 吸电子基319. Huckel rule 休克尔规则320. Hinsberg test 兴斯堡试验321. infrared spectrum 红外光谱322. Michael reacton 麦克尔反应323. halogenated hydrocarbon 卤代烃324. haloform reaction 卤仿反应325. systematic nomenclatur 系统命名法e326. Newman projection 纽曼投影式327. aromatic compound 芳香族化合物328. aromatic character 芳香性r329. Claisen condensation reaction克莱森酯缩合反应330. Claisen rearrangement 克莱森重排331. Diels-Alder reation 狄尔斯-阿尔得反应332. Clemmensen reduction 克莱门森还原333. Cannizzaro reaction 坎尼扎罗反应334. positional isomers 位置异构体335. unimolecular elimination reaction 单分子消除反应336. unimolecular nucleophilic substitution 单分子亲核取代反应337. benzene 苯338. functional grou 官能团p339. configuration 构型340. conformation 构象341. confomational isome 构象异构体342. electrophilic addition 亲电加成343. electrophilic reagent 亲电试剂344. nucleophilic addition 亲核加成345. nucleophilic reagent 亲核试剂346. nucleophilic substitution reaction亲核取代反应347. active intermediate 活性中间体348. Saytzeff rule 查依采夫规则349. cis-trans isomerism 顺反异构350. inductive effect 诱导效应t351. Fehling’s reagent 费林试剂352. phase transfer catalysis 相转移催化作用353. aliphatic compound 脂肪族化合物354. elimination reaction 消除反应355. Grignard reagent 格利雅试剂356. nuclear magnetic resonance 核磁共振357. alkene 烯烃358. allyl cation 烯丙基正离子359. leaving group 离去基团360. optical activity 旋光性361. boat confomation 船型构象362. silver mirror reaction 银镜反应363. Fischer projection 菲舍尔投影式364. Kekule structure 凯库勒结构式365. Friedel-Crafts reaction 傅列德尔-克拉夫茨反应366. Ketone 酮367. carboxylic acid 羧酸368. carboxylic acid derivative 羧酸衍生物369. hydroboration 硼氢化反应370. bond oength 键长371. bond energy 键能372. bond angle 键角373. carbohydrate 碳水化合物374. carbocation 碳正离子375. carbanion 碳负离子376. alcohol 醇377. Gofmann rule 霍夫曼规则378. Aldehyde 醛379. Ether 醚380. Polymer 聚合物。

地球化学惰性气体Lecture19_ChemicalGeodynamics_noblegases

• Heat alone suggests layering: BSE U, Th and K produce 19.2 TW; crustal heat production is 5-10 TW, and a uniformly depleted mantle produces 7 TW. Another 2-7 TW is elsewhere.
• This implies a boundary layer in the mantle that passes heat (by conduction) but mostly retains 4He
10
Geochemistry of He • So where does the 3He in the upper mantle come from?
• To remain undegassed, the reservoir must never be circulated past a mid-ocean ridge. Geochemists therefore presume it resides in the lower mantle and that convection is either layered or sluggish.
• 4He is produced by radioactive decay and we know quite precisely how much heat is liberated per alpha particle for terrestrial U and Th abundances (10-12 J/4He)
Lecture 19: Noble Gas Geochemistry
• Questions

稀有气体知识点

稀有气体知识点名称“noble gases”在十九世纪被化学家发现以来，由于深入理解其性质而多次改名。

原本它们被称为稀有气体（rare gases），因为化学家认为它们是很罕见的。

不过，这种说法只适用其中部分元素，并非所有都很少见。

例如氩气（Ar, argon）在地球大气层的含量占0.9%，胜过二氧化碳；而氦气（He, helium）在地球大气层的含量确实很少，但在宇宙却是相当充沛，它占有25%，仅次于氢。

所以化学家又改称为惰性气体（又称钝气，inert gases），表示它们的反应性很低，不曾在自然中出现化合物过。

对于那些早期需借由化合物来寻找元素的科学家，这些元素是比较难以寻找的。

不过，最近的研究指出他们是可以和其他元素结合成化合物（此即稀有气体化合物），只是需要借助人工合成的方式。

故最后改称为贵重气体（又称贵族气体、贵气体或高贵气体，noble gases），这个称呼是源自德语的Edelgas所翻译来的，是由雨果·埃德曼于1898年所定名。

“noble”与黄金等的“贵金属”类似，表示它们不易发生化学反应，但并非不能产生任何化合物。

在中文译名方面，各有各不同的称呼。

中国大陆全国自然科学名词审定委员会于1991年公布的《化学名词》中正式规定“noble gases”称为稀有气体一词。

香港教育局的《中学化学科常用英汉词汇》称“noble gases”为（高）贵气体，而一般社会仍有使用惰性气体的称呼。

而台湾方面，由国立编译馆的国家教育研究院建议常称“noble gases”为惰性气体，比较少用钝气、稀有气体等，也有被称为高贵气体。

稀有气体的得名稀有气体的单质在常温下为气体，且除氩气外，其余几种在大气中含量很少（尤其是氦），故得名“稀有气体”，历史上稀有气体曾被称为“惰性气体”，这是因为它们的原子最外层电子构型除氦为1s外，其余均为8电子构型（ns2np6，均为上标），而这两种构型均为稳定的结构。

现代大学英语精读lesson24

现代大学英语精读 lesson000000001000
01
Lesson 11
The Midnight Visitor
is not as good as you thought The blackboard is covered with geometrical figures like squares and triangles. : to investigate one’s behavior, background The little girl slipped (on the ice), but she laughed. without being able to move one’s body check (up) on sb. to behave riskily disillusioned with sb. to go somewhere quietly and quickly, in The queen extended a warm welcome to the 现代大学英语精读lesson00000000100001 feeling disappointed and unhappy The blackboard is covered with geometrical figures like squares and triangles. Don’t hesitate to tell me if you have any problem. The queen extended a warm welcome to the Take chances is not as good as you thought She raised hell when she found she had been cheated. (of a breeze) blowing strongly disillusioned disillusioned h. quietly and secretly Raise the devil with stiff adj. to discover whether it is true/safe/correct She is a girl who hesitates at nothing. because sb. The bird extended its wings in flight. because sb.

Mutations in the Helicase-Like Domain of Protein 1a Alter the Sites of RNA-RNA Recombination in BMV

1995, 69(4):2547.J. Virol. P D Nagy, A Dzianott, P Ahlquist and J J Bujarskibrome mosaic virus.1a alter the sites of RNA-RNA recombination in Mutations in the helicase-like domain of protein /content/69/4/2547Updated information and services can be found at: These include:CONTENT ALERTSmore»cite this article), Receive: RSS Feeds, eTOCs, free email alerts (when new articles /site/misc/reprints.xhtml Information about commercial reprint orders: /site/subscriptions/To subscribe to to another ASM Journal go to: on May 15, 2013 by Ohio State University Libraries/Downloaded fromJ OURNAL OF V IROLOGY,Apr.1995,p.2547–2556Vol.69,No.4 0022-538X/95/$04.00ϩ0Copyright᭧1995,American Society for MicrobiologyMutations in the Helicase-Like Domain of Protein1a Alter theSites of RNA-RNA Recombination in Brome Mosaic VirusPETER D.NAGY,1ALEKSANDRA DZIANOTT,1PAUL AHLQUIST,2AND JOZEF J.BUJARSKI1*Plant Molecular Biology Center and Department of Biological Sciences,Northern Illinois University,De Kalb,Illinois60115,1and Institute for Molecular Virology and Department of Plant Pathology,University of Wisconsin—Madison,Madison,Wisconsin537062Received2August1994/Accepted12January1995A system that uses engineered heteroduplexes to efﬁciently direct in vivo crossovers between brome mosaicvirus(BMV)RNA1and RNA3(P.Nagy and J.Bujarski,A90:6390–6394,1993)hasbeen used to explore the possible involvement of BMV1a protein,an essential RNA replication factor,in RNArecombination.Relative to wild-type1a,several viable amino acid insertion mutations in the helicase-likedomain of BMV1a protein affected the nature and distribution of crossover sites in RNA3-RNA1recombinants.At24؇C,mutants PK19and PK21each increased the percentage of asymmetric crossovers,in which the RNA1and RNA3sites joined by recombination were not directly opposite each other on the engineered RNA3-RNA1heteroduplex used to target recombination but rather were separated by4to85nucleotides.PK21and another1a mutant,PK14,also showed increases in the fraction of recombinants containing nontemplated U residuesat the recombination junction.At33؇C,the highest temperature that permitted infections with PK19,which istemperature sensitive for RNA replication,the mean location of RNA1-RNA3crossovers in recombinantsrecovered from PK19infections was shifted by nearly25bp into the energetically less stable side of theRNA1-RNA3heteroduplex.Thus,mutations in the putative helicase domain of the1a protein can inﬂuenceBMV RNA recombination.The results are discussed in relation to models for recombination by templateswitching during pausing of RNA replication at a heteroduplexed region in the template.The apparently modular evolution of positive-strand RNA viruses,natural sequence rearrangements in such viruses,and the presence of cellular sequence elements in some viral ge-nomes(for reviews,see references12,14,15,20,24,31,and 34)all indicate an important role for recombination in RNA virus variation.Several lines of evidence suggest that recom-bination in RNA viruses can occur via a copy choice mecha-nism due to strand switching by viral RNA-dependent RNA polymerase(replicase)(20,24).Possible pathways for recom-bination by template switching have been proposed for several positive-strand RNA viruses.For turnip crinkle virus,a pro-moter-like RNA element was suggested to facilitate reinitia-tion by replicase-nascent strand complexes that had dissociated from their original template RNA(8,9).For brome mosaic virus(BMV),local heteroduplexes between viral RNAs were demonstrated to promote and direct recombination(6,28,29). Similar heteroduplex-mediated mechanisms have been sug-gested to be responsible for inserting bovine polyubiquitin mRNA sequences into bovine diarrhea virus RNA(26)and to facilitate intertypic recombination in poliovirus(30).Kirke-gaard and Baltimore also provided genetic evidence for tem-plate switching in poliovirus recombination(21).BMV is a tripartite RNA virus whose RNA3encodes the3a movement protein and the coat protein,which are involved in infection spread(27),while RNA1and RNA2encode proteins 1a and2a,which are required for RNA replication(1).Re-combination has been targeted between BMV RNA1and RNA3by inserting short,antisense RNA1segments into RNA3(29).Crossover sites in the resulting recombinants were clustered within or immediately to one side of the heterodu-plex engineered between the parental RNA3and RNA1(29). This pattern of crossing over suggested that the recombinants might result from occasional template switching by the viral RNA replicase at the heteroduplex between RNA1and RNA3,possibly because of difﬁculties in unwinding stable por-tions of the heteroduplex.BMV RNA replication proteins1a and2a each share se-quence conservation with nonstructural proteins of the animal alphaviruses and numerous plant RNA viruses.2a contains a central conserved domain that likely represents the RNA poly-merase catalytic unit(1,22).1a contains an N-terminal m7G methyltransferase-like domain and a C-terminal helicase-like domain(1).This latter domain contains six conserved motifs related to known helicases(16),and mutations in or near these motifs abolish or perturb BMV RNA synthesis(23).1a and2a interact in vitro(19)to form a complex required for RNA replication in vivo(11),and the regions responsible for this 1a-2a interaction have been mapped(18).Consistent with the possible association of helicase and polymerase functions in a 1a-2a complex,BMV RNA-dependent RNA polymerase ex-tracts show a signiﬁcant,though not unlimited,ability to copy through double-stranded regions made by annealing portions of an RNA template to complementary cDNAs(2). Together,the results cited above suggest that some BMV RNA recombination events might occur when the putative1a helicase domain fails to carry out or pauses in its proposed role of unwinding duplex regions of the template to facilitate con-tinued polymerase elongation(1).When progress on the orig-inal template is so impeded,the polymerase might sometimes have the opportunity to switch to copying the adjacent single-stranded region of a heteroduplexed RNA strand.Accordingly, in the experiments reported here,we examined the possible effects of mutations within the1a helicase-like domain on the frequency or sites of heteroduplex-mediated recombination between BMV RNA1and RNA3.The results revealed several effects of1a mutations on recombination,including,for a tem-perature-sensitive(ts)1a mutant,a temperature-dependent*Corresponding author.2547 on May 15, 2013 by Ohio State University Libraries / Downloaded fromshift of crossovers toward the energetically less stable portions of the RNA1-RNA3heteroduplex.Other non-ts1a mutants showed different alterations in the distribution of recombina-tion sites and/or increased incidence of nontemplated U resi-dues at recombination junctions.Thus,consistent with recom-bination as a by-product of RNA replication,mutations in the BMV1a RNA replication protein can inﬂuence the distribu-tion of recombination sites between BMV RNAs.MATERIALS AND METHODSMaterials.Plasmids pB1TP3,pB2TP5,and pB3TP7(17)were used to synthe-size infectious in vitro transcripts of wild-type(wt)BMV RNA1,RNA2,and RNA3.Plasmids pB1PK14,pB1PK19,and pB1PK21(23)were used to synthe-size BMV RNA1transcripts bearing the PK14,PK19,and PK21mutations, respectively.Plasmid pPN8(Ϫ)(29)was used to obtain transcripts of the PN8(Ϫ) derivative of BMV RNA3.Moloney murine leukemia virus reverse transcriptase, restriction enzymes,and T7RNA polymerase were from GIBCO-BRL(Gaith-ersburg,Md.),and a Sequenase kit was from United States Biochemical Corpo-ration(Cleveland,Ohio).In vitro transcription,whole-plant infections,and RNA puriﬁcation.Full-length,capped RNA transcripts were made from Eco RI-linearized plasmids according to previously published procedures(17).Chenopodium quinoa leaves were inoculated with a mixture of the transcribed BMV RNA components as described in reference28.Brieﬂy,a mixture of1␮g of each transcript in15␮l of inoculation buffer(10mM Tris[pH8.0],1mM EDTA,0.1%celite,0.1% bentonite)was used to inoculate one fully expanded leaf.In each experiment,six separate leaves were inoculated for each RNA1mutant-temperature combina-tion.Each such inoculation experiment was repeated two or three times.The inoculated C.quinoa plants were maintained in a growth chamber at either24or 33ЊC(the temperature was lowered by2ЊC during the dark period for10h)for 2weeks.Plants that were inoculated with PK19did not produce any local lesions at35and37ЊC.Local lesions were counted14days postinoculation,and for each RNA1mutant-temperature combination,lesions selected at random were ex-cised for RNA extraction.Total RNA was extracted from each local lesion,using phenol-chloroform extraction in a1%sodium dodecyl sulfate–50mM glycine–50 mM NaCl–10mM EDTA(pH9.0)buffer.Ampliﬁcation of recombinant RNA3s by RT-PCR,cloning,and sequencing. The3Ј-proximal sequences in recombinant BMV RNA3molecules were ampli-ﬁed with a reverse transcription-PCR(RT-PCR)procedure exactly as described in reference28.Brieﬂy,ﬁrst-strand cDNA was synthesized in a10-␮l reaction mixture that contained4␮l of the extract RNA,1mM each deoxynucleoside triphosphate(dNTP),1U of RNasin per␮l,25pMﬁrst-strand synthesis primer (primer1[CAGTGAATTCTGGTCTCTTTTAGAGATTTACAG],which is complementary to the3Ј-terminal23nucleotides[nt]of all of the BMV virion RNAs[3]),50mM KCl,20mM Tris-HCl(pH8.4),3mM MgCl2,and200U of Moloney murine leukemia virus reverse transcriptase.After incubation at55ЊC for40min,the reverse transcriptase was heat inactivated at95ЊC for5min,the volume was adjusted to50␮l,and the mixture was subjected to PCR ampliﬁca-tion.The PCR mixture contained50mM KCl,20mM Tris-HCl(pH8.4),1.5mM MgCl2,1mM each dNTP,25pM primer1(see above),25pM second-strand primer(primer2[CTGAAGCAGTGCCTGCTAAGGCGGTC],which corre-sponds to nt367to392from the3Јend of wt BMV RNA3),and1U of Taq DNA polymerase(Perkin-Elmer).After40thermocycles(94ЊC for1min,60ЊC for1 min,and72ЊC for2min),the resulting cDNA was analyzed in1%agarose gels. The use of primer1created an Eco RI site(underlined)at the3Јend of the cDNA products.The resulting cDNA products were digested with restriction enzymes Eco RI and Xba I and ligated between the corresponding sites in the polylinker of the pGEM3zf(Ϫ)cloning vector(Promega).The sites of crossovers between RNA3and RNA1in the recombinants were determined by sequencing with the Sequenase kit(U.S.Biochemical)according to the manufacturer’s speciﬁcations.Stability of1a mutants in C.quinoa.The3Ј-half sequences of wt,PK14,PK19, and PK21RNA1s obtained from eight separate local lesions of C.quinoa14days after inoculation were ampliﬁed by RT-PCR using primers1(see above)and3 (5Ј-GACCAAGCTTCGAAGAAGAAGGCG-3Ј,corresponding to positions 1583to1607of wt RNA1).Conditions of RT-PCR were the same as described above except that reverse transcription was performed at37ЊC and the param-eters for PCRs were as follows:94ЊC for1min,55ЊC for1min,and72ЊC for3 min.After40thermocycles,the PCR products were puriﬁed by phenol-chloro-form extraction and ethanol precipitation.Restriction enzyme digestion of the resulted PCR products with either Bam HI(for PK19and PK21)or Apa I(for PK14)was used to demonstrate the presence of the corresponding linker se-quences in the progenies of the particular RNA1mutants.Analysis of growth characteristics of selected RNA3recombinants by North-ern(RNA)blotting.Full-length cDNA clones of two unusual recombinants derived from PK19infections(marked by triangles in Fig.3)were generated by replacing the3Ј-terminal Xba I-Eco RI fragment of wt RNA3cDNA clone pB3TP7with the corresponding Xba I-Eco RI fragments derived from the cloned partial cDNAs of the particular recombinant(see above).In vitro-transcribed RNA3transcripts representing sequences of the selected recombinants were used together with one of the RNA1s(wt,PK14,PK19,and PK21)and wt RNA2 to inoculate leaves of C.quinoa.After inoculation,plants were incubated at24 or33ЊC.Total RNA extracts were prepared as described above from four sep-arate local lesions for each mutant RNA1-recombinant RNA3combination14 days after inoculation.One-tenth of each total RNA extract was used for1% agarose gel electrophoresis;this procedure was followed by a transfer to a nylon membrane(Hybond Nϩ;Amersham)and hybridization to a32P-radiolabeled BMV RNA positive-strand-speciﬁc probe under the conditions described by Kroner et al.(22).Statistical analyses.For the distribution of crossover sites observed for each mutant-temperature combination,the mean recombination site and the standard deviation about that mean were calculated by using computer program Super-ANOVA(Abacus Concepts,Inc.)run on a Macintosh computer.To assess whether the distribution of crossover sites differed signiﬁcantly between any two mutants,the same program was used to apply the Duncan new multiple-range procedure(13).This procedure utilizes an algorithm which makes all pairwise comparisons of the means by ordering them from smallest to largest and then uses the expected mean square values,the sample size from each group,the level of signiﬁcance,and tabulated values of the Duncan statistics to compute critical ranges.These ranges are thereafter compared with the differences between the ordered means to identify which means are signiﬁcantly different from any others (33).RESULTSTo test whether mutations in a BMV-encoded protein re-quired for RNA replication could inﬂuence RNA-RNA re-combination,we examined three viable1a mutants,designated PK14,PK19,and PK21(Fig.1A).Each of these mutants has a two-amino-acid insertion within the helicase-like domain of1a. As reported previously(23),PK14and PK21do not cause any conspicuous changes in BMV RNA replication in barley pro-toplasts.By contrast,PK19is ts,supporting a wt level of BMV RNA replication at24ЊC but no RNA synthesis at35ЊC.To target recombination events between BMV RNA1and RNA3,we used a previously described RNA3derivative,des-ignated PN8(Ϫ)(29).As illustrated in Fig.1A,PN8(Ϫ)RNA3 contains a long,chimeric3Јnoncoding region that serves two purposes.First,to promote recombination with RNA1, PN8(Ϫ)RNA3contains a141-nt-long antisense RNA1se-quence,inserted immediately3Јto the coat protein open read-ing frame(region bounded by dotted lines in Fig.1A).This antisense RNA1insert,which is punctuated at its5Јend by three regions of mismatch with RNA1,enables PN8(Ϫ)RNA3 to form an imperfect heteroduplex with RNA1(Fig.1B)that resembles the imperfect double-stranded regions in proposed recombination intermediates between wt BMV RNAs(6,28, 29).As shown previously(29),when cells are infected with wt RNA1,wt RNA2,and PN8(Ϫ)RNA3,these features lead to the high-frequency appearance of recombinant variants of RNA3,in which crossing over within the region of the Fig.1B heteroduplex has replaced the3Ј-proximal segment of PN8(Ϫ) RNA3with that from RNA1.Since the3Ј-terminal200nt of all BMV RNAs are almost perfectly conserved,such recombi-nants are fully competent for replication.Second,the extreme3Ј-terminal sequences of PN8(Ϫ) RNA3following the antisense RNA1insert contain BMV se-quences essential for directing negative-strand RNA synthesis. However,this region also bears a previously described(29)set of deletions,duplications,and insertions that cause PN8(Ϫ) RNA3to replicate and accumulate more poorly than either wt RNA3or the heteroduplex-mediated recombinants in which these debilitated PN8(Ϫ)3Јsequences are replaced by the wt 3Јnoncoding sequences of RNA1.Thus,the heteroduplex-mediated PN8(Ϫ)-RNA1recombinants have a selective repli-cative advantage over the parental PN8(Ϫ)RNA3,facilitating their detection and recovery.Recombination assays with wt and mutant1a genes.Leaves of C.quinoa,a local lesion host for BMV,were inoculated with2548NAGY ET AL.J.V IROL.on May 15, 2013 by Ohio State University Libraries /Downloaded froma mixture of in vitro-transcribed RNA1(either wt or one of the PK mutants),wt RNA2,and PN8(Ϫ)RNA3.To analyze whether the ts mutant PK19had a ts phenotype in recombina-tion,half of the inoculated plants were kept at24ЊC and half were kept at33ЊC.As an initial assay for recombination,indi-vidual local lesions were excised from the inoculated leaves at 14days postinoculation,total RNA was isolated separately from each lesion,and the3Јnoncoding regions of the RNA3 progeny were ampliﬁed by RT-PCR,electrophoresed in aga-rose gels,and visualized by ethidium bromide staining as de-scribed in Materials and Methods.Theﬁrst-strand cDNA primer was complementary to the extreme3Јsequence con-served on all BMV RNAs,while the second-strand primer corresponded to a sequence within the BMV coat protein gene,making the PCR reaction speciﬁc for RNA3derivatives (Fig.1A).The PCR product so ampliﬁed for the parental PN8(Ϫ)RNA3(Fig.1A)was860nt in length,while RNA3 recombinants produced by crossovers between PN8(Ϫ)RNA3 and RNA1within the region of their complementarity(Fig. 1B)gave rise to smaller PCR products due to replacement of the long3Јnoncoding region of PN8(Ϫ)(743nt)with the shorter3Јnoncoding region of RNA1(274nt).Consistent with such recombination,a major PCR product smaller than860nt was found in84to88%of lesions from inoculations involving wt RNA1and100%of lesions from inoculations with PK14, PK19,and PK21RNA1mutants(Table1).The sizes of these products varied from approximately350to525nt among dif-ferent lesions(Fig.2).Despite this variation among different lesions,95%of recombinant-containing lesions each contained only a single major type of recombinant RNA3,as determined by agarose gel electrophoresis and subsequent cloning of the RT-PCR products and sequencing of at leastﬁve clones per lesion in preliminary experiments.Only one lesion of those in Fig.2accumulated signiﬁcant levels of two recombinants(Fig. 1A,lane16).The860-nt PCR band corresponding to the parental PN8(Ϫ)RNA3was also detected in approximately 30%of all recombinant-containing lesions,usually as a weaker, more slowly migrating band accompanying a stronger recom-binant PCR product(Fig.2).To test for possible RT-PCR-dependent recombination or other PCR artifacts,a sample of each inoculum mixture[con-taining wt or mutant RNA1,wt RNA2,and PN8(Ϫ)RNA3 on May 15, 2013 by Ohio State University Libraries / Downloaded fromtranscripts]was subjected to RT-PCR with the same primers and conditions used to test total nucleic acid extracts from C.quinoa local lesions.In these control reactions,the expected 860-nt band corresponding to PN8(Ϫ)RNA3was always the only RT-PCR product observed (Fig.2B,lane ⌽).As another control,multiple independent PCR ampliﬁcations were some-times performed on the cDNA products derived from a single local lesion.Such PCR reactions always reproducibly ampliﬁed a common recombinant species,while,as noted above,PCR ampliﬁcations of cDNAs from different lesions produced prod-ucts of various sizes.Together,these results ruled out the possibility that the observed PN8(Ϫ)-RNA1recombinants were generated during RT-PCR rather than during BMV in-fection.To determine whether the 1a gene linker insertion muta-tions were maintained during the formation of recombinant RNA3s,we tested the stability of the RNA1mutations during infection.The 3Јhalf of RNA1,which includes all three mu-tations (Fig.1A),was ampliﬁed by RT-PCR with primers 1and 3.The same total RNA extracts of C.quinoa were used for these studies as for the recombinant RNA3studies (see above).The presence of the inserted Bam HI or Apa I linker sequences was demonstrated for eight separate samples in each mutant RNA1-recombinant RNA3combination by re-striction enzyme digestion (Bam HI for PK19and PK21and Apa I for PK14).Similar to control results obtained in parallel reactions with mixtures of in vitro-transcribed RNA1(either wt,PK14,PK19,or PK21),RNA2,and RNA3,we found that the RT-PCR-ampliﬁed RNA1-speciﬁc PCR products were cut by the appropriate restriction enzyme (to 95to 100%com-pleteness;results not shown).This ﬁnding demonstrates that 1a gene mutations were stably maintained during infection for all three PK n mutants and that any possible 1a revertants that might have emerged remained at most minor species in the infection.Effect of mutations in the 1a helicase-like domain on the distribution of crossover sites.To compare the distributions of crossover sites in the presence of wt and mutant 1a genes,the PCR-ampliﬁed,RNA3-speciﬁc cDNA products were cloned into a suitable plasmid and sequenced as described in Materi-als and Methods.To provide a representative distribution of crossover sites for comparison,22to 34clones were sequenced for each RNA1mutant-temperature combination.To ensure that each sequence represented an independentrecombinationFIG.2.Characterization of BMV RNA3recombinants by agarose gel electrophoresis of RNA3-speciﬁc PCR products obtained by RT-PCR using primers 1and 2(as speciﬁed in Fig.1A)from total RNA preparations extracted from individual local lesions as described in Materials and Methods.The RT-PCR products of progeny RNA3derived from 18separate local lesions that were obtained from either wt (A)or PK19(B)RNA1infection at 33ЊC are ne ⌽shows a control RT-PCR ampliﬁcation that was performed by using a mixture of in vitro-transcribed wt RNA1and RNA2and PN8(Ϫ)RNA3.Positions of PCR products corresponding to the length of the inoculated PN8(Ϫ)RNA3(I)and of the newly emerged recombinants (R)are shown.The sizes of PCR products can be estimated by comparison with a standard 1-kb DNA ladder (GIBCO-BRL)shown in lanes marked 1kb ladder.Note the homogeneity of RT-PCR products within the samples and their size variation among the samples.TABLE 1.Characterization of crossover sites obtained from infections with three BMV 1a protein mutantsMutantTreatment (ЊC)No.of clones sequenced a%Incidence of:Recombination bNontemplated nucleotides cSigniﬁcantly asymmetriccrossovers dwt 2425848Ϯ116PK14242310022Ϯ222PK1924341006Ϯ150PK21242610027Ϯ235wt 3325884Ϯ18PK1433221005Ϯ114PK193327100011PK2133251008Ϯ224a Each clone represents an independent RNA3-RNA1recombinant isolated from a separate local lesion.bPercentage of lesions that contained recombinant RNA3molecules as determined by size fractionation of RT-PCR products by agarose gel electrophoresis.cPercentage of recombinants that contained nontemplated nucleotides at the crossover sites.Standard deviations were calculated from the analysis of recombinants isolated from 12leaves (one to three lesions per leaf).dPercentage of recombinants that had the PN8(Ϫ)RNA3site more than 3bp away from the RNA1site on the heteroduplex formed between complementary regions of PN8(Ϫ)RNA3and RNA1(see Fig.3).2550NAGY ET AL.J.V IROL .on May 15, 2013 by Ohio State University Libraries/Downloaded fromevent,each clone was derived from an independent local le-sion.This approach was judged to be the most productive since,as noted above,95%of the recombinant-containing le-sions had a single major recombinant species.The sequencing conﬁrmed that the PCR products smaller than860nt represented recombinants between PN8(Ϫ)and RNA1.Recombination invariably occurred within or immedi-ately adjacent to the region of engineered complementarity between the two starting RNAs(Fig.1B).Figure3A shows the distributions of crossover sites observed for infections at24ЊC involving the wt1a gene or mutants PK14,PK19,and PK21. For PK14and wt1a,the crossover distributions observed at 24ЊC were quite similar(Fig.3A).For both,the majority of crossovers clustered between50and70nt from the left side of the heteroduplex portrayed in Fig.3A.Also,a similar recom-bination hot spot was observed with both wt1a and PK14, represented by seven and nine crossovers,respectively,that occurred62to63nt from the left side of the heteroduplex.For these and most other wt and PK14recombinants,the crossover sites on PN8(Ϫ)RNA3and RNA1were aligned within0to3 nt of each other on the illustrated heteroduplex;hereafter, such crossovers will be referred to as symmetric.The remain-ing recombinants(16%for wt and22%for PK14)resulted from asymmetric crossovers linking PN8(Ϫ)and RNA1se-quences that were widely separated on the heteroduplex. Among nine asymmetric recombinants recovered from infec-tions with wt1a or PK14at24ЊC,seven had the crossover site on PN8(Ϫ)RNA3(upper strand in Fig.3A)displaced in the3Јdirection along PN8(Ϫ)from the crossover site on RNA1, while two had crossover sites in the opposite orientation. Unlike the case for PK14,the crossover distributions result-ing from PK19and PK21infections showed signiﬁcant differ-ences from wt1a infections.At24ЊC,the incidence of asym-metric crossovers was signiﬁcantly increased,to35%of total recombinants for PK21and to50%for PK19,versus16%for wt1a(Fig.3A and Table1).Moreover,the average separation between PN8(Ϫ)and RNA1crossover endpoints in asymmet-ric crossovers was much greater for PK19and PK21than for wt 1a or PK14(Fig.3A).The most asymmetric PK19crossovers, e.g.,joined PN8(Ϫ)and RNA1sites separated by up to85nt in the heteroduplex.The differences in crossover distributions between wt1a and the1a mutants might reﬂect differences in either the genera-tion or subsequent viability of different types of recombinants. To investigate if the most unusual recombinant RNA3s ob-served in mutant1a backgrounds were viable in the wt1a background,we constructed full-length cDNA clones of two of the most unusual RNA3recombinants that were found only in PK19infections and tested their growth characteristics in in-fections involving wt and mutant1a genes.One of the two recombinant RNA3s was recombinant1(marked by a triangle in the ts PK19B sequence in Fig.3A),which contained an unusually long3Јnoncoding region(ϳ420nt)resulting from an asymmetric crossover.The other selected recombinant RNA3was recombinant5(marked by a triangle in the ts PK19 sequence in Fig.3B).This recombinant had a very short3Јnoncoding region(ϳ250nt)resulting from a crossover on the left side of the putative heteroduplex.In vitro-transcribed RNA1(wt,PK14,PK19,or PK21),wt RNA2,and one of the selected recombinant RNA3s were used to inoculate leaves of C.quinoa.The inoculated plants were incubated either at24or 33ЊC for2weeks.Northern blot analysis with a BMV-speciﬁc RNA probe of total RNA extracts made from separate local lesions was used to determine the accumulation of progeny RNAs.Figure4A shows that both recombinant RNA3s were viable and accumulated to very similar levels in wt,PK14,PK19,and PK21infections at room temperature(lanes1to8). Recombinant1accumulation at33ЊC was lower than that at 24ЊC but comparable in wt,PK14,and PK21infections(Fig. 4B,lanes9,10,and12)and actually greater than recombinant 1accumulation in PK19infections(lane11).At33ЊC,recom-binant5accumulation was not easily visible on the Northern blots in any of the infections(Fig.4B,lanes13to16).However, RT-PCR analysis with primers1and2demonstrated that recombinant5was present in local lesion infections with either wt or one of the PK n RNA1derivatives(Fig.4C,lanes21to 27).These data demonstrated that two of the most unusual recombinant RNA3s derived from PK191a infections were equally viable in infections with a wt,PK14,or PK211a gene. Thus,these results argue that the unusual recombinant RNA3s would have been observed if they had been generated in in-fections with any of these RNA1derivatives.Taken together, the observed differences in the nature of recombinants are unlikely to result from differences in postrecombination selec-tion.Comparison of average crossover sites on RNA3and RNA1. While Fig.3A reveals some notable differences between the crossover distributions associated with wt1a and the PK19and PK21mutants,the raw data in the Fig.3crossover distribu-tions are complex.Therefore,it was also useful to apply some simpler measures for objectively comparing the distributions. To this end,the mean positions and standard deviations of crossover endpoints on both PN8(Ϫ)RNA3and RNA1were plotted for infections with wt1a and each1a mutant.This display(Fig.5)makes the major conclusions from Fig.3A even more apparent.For wt1a infections at24ЊC,the average cross-over endpoints on PN8(Ϫ)RNA3(upper strand)and RNA1 (lower strand)were immediately adjacent to each other in the heteroduplex,at residues62and61,respectively.The positions of the average crossover endpoints in PK14infections were similar to those for the wt;i.e.,they were separated from the wt values by less than half of the standard deviation of either distribution.In contrast,for PK19infections at24ЊC,the av-erage crossover endpoints on RNA3and RNA1were markedly shifted away from each other toward the extremes of the het-eroduplex,leaving a19-nt gap reﬂecting the crossover asym-metry apparent for PK19in Fig.3A.PK21infections at24ЊC produced a pattern intermediate between those of wt1a and PK19,with a10-nt gap between the average crossover sites on RNA3and RNA1(Fig.5).Relative to infections with wt1a, the PK21pattern reﬂected primarily a leftward shift in the crossover endpoint on RNA1.Effect of1a mutation PK19at33؇C.The effect of the ts PK19 mutant on recombination was also compared with effects of wt 1a and the other1a mutants in infections at33ЊC,the highest temperature at which PK19RNA1,wt RNA2,and PN8(Ϫ) RNA3produced local lesions on C.quinoa.For wt1a and each of the three mutants,the incidence of asymmetric crossovers declined signiﬁcantly at33ЊC versus24ЊC(Fig.3and Table1). At33ЊC,most of the crossovers seen in infections with wt1a, PK14,and PK21clustered between positions60and70on the heteroduplex map of Fig.3B.PK19,however,differed from wt 1a and the other1a mutants in having a much higher incidence of crossovers in the left half of the heteroduplex,including several recombination hot spots leftward of position60.One of these recombination hot spots was located several nucleotides immediately to the left of the heteroduplex(Fig.3B).Under the template switching model,these recombinants would result from crossovers that occurred before the polymerase active site entered the heteroduplex region(see Fig.1B and Discussion). The magnitude of the leftward shift in recombination sites in PK19infections at33ЊC is particularly clear in Fig.5,where theV OL.69,1995MUTATIONS IN PROTEIN1a ALTER BMV RECOMBINATION2551on May 15, 2013 by Ohio State University Libraries /Downloaded from。

稀有气体化学

没有化学”现象。
直到1962年3月23日，英国的年轻化学家巴特利特第一个制得惰性气
体化合物——橙黄色固体 6 才改变了这一局面。此后，各种各样的稀有气体化合物被相继制得。
六氟合铂酸氙的出现标志着稀有气体化学研究的崭新领域。
六氟合铂酸氙（Xe[PtF ]）稀有气体化学的建立，开创了
氦化合物
尽管一些理论上一些氦化合物在低温高压下能稳定存在，但还没有实验能证明这一点。氦合氢离子，化学式为HeH+，是一个带正电的离子，键级为1，可以存在于气态中，通过光谱观测到。它首次发现于1925年，通过质子和氦原子在气相中反应制得。它是已知最强的酸，质子亲和能为177.8 kJ/mol。这种离子也被称为氦氢分子离子。有人认为，这种物质可以存在于自然星际物质中。不同于氦合氢离子，氢和氦构成的中性分子(HeH)在一般情况下(基态)不稳定，但它的激发态可以作为准分子存在，20世纪80年代中期首次在光谱中观测到。
氪化合物
1962年首次合成出氙的化合物后，二氟化氪（KrF2）也在1963年成功合成。同年，格罗泽等人宣布合成出四氟化氪（KrF4），但后来证实为鉴定错误，实际上是二氟化氪。另外有未经证实的报告指出发现氪含氧酸的钡盐。已有研究发现多原子离子ArKr和KrH，也有KrXe或KrXe存在的证据。
在中文译名方面，两岸三地有着不同的称呼中国大陆称为稀有气体香港称为（高）贵气体台湾方面常称惰性气体
二、发现史
威廉·拉姆塞(WilliamRamsay)是英国化学家，出生于苏格兰。因发现氦、氖、氩、氙、氡等气态惰性元素，并确定了它们在元素周期表中的位置，而获得1904年诺贝尔化学奖。
发现史
被化学家长期遗忘的角落

应用化学专业英语(课后答案和课文翻译)

应用化学专业英语(课后答案和课文翻译)Unit 1 The Roots of Chemistry I. Comprehension.1.It can be inferred from this article which one of the following items is not mainly based on practical use C. Greek chemistry2. It was B. Empedocless who first introduced the idea that all things are not formed from just one element.3. In the development of Greek chemistry, D. Democritus was the first one definiting the ultimately constituents of matter?4. According to Plato, there are B. 4 �Delements‖ whose faces are constituted by regular polygons.5. In the last paragraph,authors think that experiment DD.can deal with the reactions by which one substance is converted into anotherII. Make a sentence out of each item by rearranging the words in brackets.1. The purification of an organic compound is usually a matter of considerable difficulty, and itis necessary to employ various methods for this purpose.2. Science is an ever-increasing body of accumulated and systematized knowledge and is also anactivity by which knowledge is generated.3. Life, after all, is only chemistry, in fact, a small example of chemistry observed on a singlemundane planet.4. People are made of molecules; some of the molecules in people are rather simple whereasothers are highly complex.5. Chemistry is ever present in our lives from birth to death because without chemistry there isneither life nor death.6. Mathematics appears to be almost as humankind and also permeates all aspects of human life,although many of us are not fully aware of this.III. Translation.1. (a)化学过程； (b)自然科学；（c）蒸馏技术(a) chemical process (b) natural science (c) the technique ofdistillation 2. 正是原子构成铁、水、氧等。

E314

--- lesson 14 A noble gangster 贵族歹徒--- Listen to the tape then answer the question below.^听录音，然后回答以下问题。

--- How did Hawkwood make money in times of peace?There was a time when the owners of shops and businesses in Chicago had to pay large sums of money to gangsters in return for 'protection'.^曾经有一个时期,芝加哥的店主和商行的老板们不得不拿出大笔的钱给歹徒以换取'保护'。

If the money was not paid promptly, the gangsters would quickly put a man out of business by destroying his shop.^如果交款不及时,歹徒们就会很快捣毁他的商店,让他破产。

Obtaining 'protection money' is not a modern crime.^榨取'保护金'并不是一种现代的罪恶行径。

As long ago as the fourteenth century, an Englishman, Sir John Hawkwood, made the remarkable discovery^早在14世纪,英国人约翰.霍克伍德就有过非凡的发现:that people would rather pay large sums of money than have their life work destroyed by gangsters.^'人们情愿拿出大笔的钱,也不愿毕生的心血毁于歹徒之手。

The_Loons高级英语[1]

Phrases
• • • • • • • • • • 1)一瘸一拐地走路 walk in limping manner 2)令人尴尬的人(或事) presence that causes embarrassment 3)不会笑的眼睛 eyes that do not smile 4)哀鸣 a sound that ululates 5)令人发冷的嘲笑 mockery that chills
• • • • • • • •
6)还在燃烧的白桦圆木 a birch log that is burning 7)令人生畏的希望 hope that terrifies 8)繁华的度假胜地 a resort that flourishes 9)强烈的气味 odours that penetrate
• Part II. Para.3 – Para.4 (p. 218)
The whole story
• Part III. Para. 5 on page 218 – end.
Analogy between the loons and Piquette
• Part II
Section 1. Para.3 (p.206) – Para.6 (p.208)
conflicts
• Conflict between the loons (nature) and civilization • Clash between culture of Metis and whitedominating society
climax
• No one can ever describe that ululating sound ,the crying of the loons ,and no one who has heard it can ever forget it .Plaintive, and yet with a quality of chilling mockery, those voices belonged to a world separated by aeons from our neat world of summer cottages and the lighted lamps of home. • 潜水鸟的鸣声悲凉凄厉，任何人都无法形容，任何人听后也难以忘怀。那种悲凉之中又带着冷嘲的声调属于另外一个遥远的世界，那世界与我们这个有着避暑别墅和居家灯火的美好世界相隔不下亿万年之遥。 • According to the description of the sad sound of the loons and the surrounding around, we are led to the actual situation of Piquette the theme. She was on behalf of the group of Metis who fight to preserve their culture , value and wished that their cultural identity could be accepted, however , all of these were pushed out by the main culture of white people

地球化学_介绍 Geochemistry_Introduction

Definition and Sub-disciplines
Geochemistry uses the tools of chemistry to understand processes on Earth. The wide field of Geochemistry includes: Trace element geochemistry Isotope geochemistry Petrochemistry Soil geochemistry Sediment geochemistry Marine geochemistry Atmospheric geochemistry Planetary geochemistry Geochemical thermodynamics and kinetics Aquatic chemistry Inorganic geochemistry Organic geochemistry Biogeochemistry Environmental geochemistry …
Chemical Properties of the Elements
Pauling Scale The Pauling Scale is the most commonly used scale of electronegativity values. The calculations used to arrive at the numbers in the scale are complex. It is most common to simply know the results of those calculations. The scale is based on Fluorine having the largest electronegativity with a value of 4.0. The Francium atom is assigned the lowest electronegativity value at 0.7. All other values are located between these extremes. Examples: Li--1.0 Be--1.5 B--2.0 C--2.5 N--3.0 O--3.5 F--4.0. R.S. Mulliken (1934) proposed an electronegativity scale in which the electronegativity, χM is related to the electron affinity EAv (a measure of the tendency of an atom to form a negative species) and the ionization potential IEv (a measure of the tendency of an atom to form a positive species) by the equation: χM = (IEv + EAv)/2 The subscript v denotes a specific valence state. The Mulliken electronegativities are expressed directly in energy units, usually electron volts.

SSAT阅读真题

SSAT 阅读真题阅读 (一 )In the sixteenth century, an age of great marine and terrestrial exploration, Ferdinand Magellan led the first expedition to sail around the world. As a young Portuguese noble, he served the king of Portugal, but he became involved in the quagmire of political intrigue at court and lost the king's favor. After he was dismissed from service to the king of Portugal, he offered to serve the future Emperor Charles V of Spain.A papal decree of 1493 had assigned all land in the New World west of 50 degrees W longitude to Spain and all the land east of that line to Portugal. Magellan offered to prove that the East Indies fell under Spanish authority. On September 20, 1519, Magellan set sail from Spain with five ships. More than a year later, one of these ships was exploring the topography of South America in search of a water route across the continent. This ship sank, but the remaining four ships searched along the southern peninsula of South America. Finally they found the passage they sought near a latitude of 50 degrees S. Magellan named this passage the Strait of All Saints, but today we know it as the Strait of Magellan.One ship deserted while in this passage and returned to Spain, so fewer sailors were privileged to gaze at that first panorama of the Pacific Ocean. Those who remained crossed the meridian we now call the International Date Line in the early spring of 1521 after ninety-eight days on the Pacific Ocean. During those long days at sea, many of Magellan's men died of starvation and disease.Later Magellan became involved in an insular conflict in the Philippines and was killed in a tribal battle. Only one ship and seventeen sailors under the command of the Basque navigator Elcano survived to complete the westward journey to Spain and thus prove once and for all that the world is round, with no precipice at the edge.The sixteenth century was an age of great ___exploration.A. cosmicB. landC. mentalD. common manE. none of the above2. Magellan lost the favor of the king of Portugal when he became involved in a political ___.A. entanglementB. discussionC. negotiationD. problemsE. none of the above3. The Pope divided New World lands between Spain and Portugal according to their location on one side or the other of an imaginary geographical line 50 degrees west of Greenwich that extends in a ___ direction.A. north and southB. crosswiseC. easterlyD. south eastE. north and west4. One of Magellan's ships explored the ___ of South America for a passage across the continent.A. coastlineB. mountain rangeC. physical featuresD. islandsE. none of the above5. Four of the ships sought a passage along a southern ___.A. coastB. inlandC. body of land with water on three sidesD. borderE. answer not available6. The passage was found near 50 degrees S of ___.A. GreenwichB. The equatorC. SpainD. PortugalE. Madrid7. In the spring of 1521, the ships crossed the ___ now called the International Date Line.A. imaginary circle passing through the polesB. Imaginary line parallel to the equatorC. areaD. land massE. answer not found in article答案：1. B2. A3. A4. C5.C,6 B 7A阅读 (二 )Marie Curie was one of the most accomplished scientists in history. Together with her husband, Pierre, she discovered radium, an element widely used for treating cancer, and studied uranium and other radioactive substances. Pierre and Marie's amicable collaboration later helped to unlock the secrets of the atom.Marie was born in 1867 in Warsaw, Poland, where her father was a professor of physics. At the early age, she displayed a brilliant mind and a blithe personality. Her great exuberance for learning prompted her to continue with her studies after high school. She became disgruntled, however, when she learned that the university in Warsaw was closed to women. Determined to receive a higher education, she defiantly left Poland and in 1891 entered the Sorbonne, a French university, where she earned her master's degree and doctorate in physics.Marie was fortunate to have studied at the Sorbonne with some of the greatest scientists of her day, one of whom was Pierre Curie. Marie and Pierre were married in 1895 and spent many productive years working together in the physics laboratory. A short time after they discovered radium, Pierre was killed by a horse-drawn wagon in 1906. Marie was stunned by this horrible misfortune and endured heartbreaking anguish. Despondently she recalled their close relationship and the joy that they had shared in scientific research. The fact that she had two young daughters to raise by herself greatly increased her distress.Curie's feeling of desolation finally began to fade when she was asked to succeed her husband as a physics professor at the Sorbonne. She was the first woman to be given a professorship at theworld-famous university. In 1911 she received the Nobel Prize in chemistry for isolating radium. Although Marie Curie eventually suffered a fatal illness from her long exposure to radium, she never became disillusioned about her work. Regardless of the consequences, she had dedicated herself to science and to revealing the mysteries of the physical world.8． The Curies' ____ collaboration helped to unlock the secrets of the atom.A. friendlyB. competitiveC. courteousD. industriousE. chemistry9. Marie had a bright mind and a __personality.A. strongB. lightheartedC. humorousD. strangeE. envious10. When she learned that she could not attend the university in Warsaw, she felt___.A. hopelessB. annoyedC. depressedD. worriedE. none of the above11. Marie ___ by leaving Poland and traveling to France to enter the Sorbonne.A. challenged authorityB. showed intelligenceC. behavedD. was distressedE. answer not available in article12. _____she remembered their joy together.A. DejectedlyB. WorriedC. TearfullyD. HappilyE. Sorrowfully13. Her ____ began to fade when she returned to the Sorbonne to succeed her husband.A. misfortuneB. angerC. wretchednessD. disappointmentE. ambition14. Even though she became fatally ill from working with radium, Marie Curie was never ____.A. troubledB. worriedC. disappointedD. sorrowfulE. disturbed(二)答案 9. B 10. B 11. A 12. A 13. C 14. C阅读 (三 ) Questions 15-19.Mount Vesuvius, a volcano located between the ancient Italian cities of Pompeii and Herculaneum, has received much attention because of its frequent and destructive eruptions. The most famous of these eruptions occurred in A. D. 79.The volcano had been inactive for centuries. There was little warning of the coming eruption, although one account unearthed by archaeologists says that a hard rain and a strong wind had disturbed the celestial calm during the preceding night. Early the next morning, the volcano poured a huge river of molten rock down upon Herculaneum, completely burying the city and filling in the harbor with coagulated lava.Meanwhile, on the other side of the mountain, cinders, stone and ash rained down on Pompeii. Sparks from the burning ash ignited the combustible rooftops quickly. Large portions of the city were destroyed in the conflagration. Fire, however, was not the only cause of destruction. Poisonous sulphuric gases saturated the air. These heavy gases were not buoyant in the atmosphere and therefore sank toward the earth and suffocated people.Over the years, excavations of Pompeii and Herculaneum have revealed a great deal about the behavior of the volcano. By analyzing data, much as a zoologist dissects a specimen animal, scientist haveconcluded that the eruption changed large portions of the area's geography. For instance, it turned the Sarno River from its course and raised the level of the beach along the Bay of Naples. Meteorologists studying these events have also concluded that Vesuvius caused a huge tidal wave that affected the world's climate.In addition to making these investigations, archaeologists have been able to study the skeletons of victims by using distilled water to wash away the volcanic ash. By strengthening the brittle bones with acrylic paint, scientists have been able to examine the skeletons and draw conclusions about the diet and habits of the residents. Finally, the excavations at both Pompeii and Herculaneum have yielded many examples of classical art, such as jewelry made of bronze, which is an alloy of copper and tin.The eruption of Mount Vesuvius and its tragic consequences have provided us with a wealth of data about the effects that volcanoes can have on the surrounding area. Today volcanologists can locate and predict eruptions, saving lives and preventing the destruction of cities and cultures.15.Herculaneum and its harbor were buried under ___lava.A. liquidB. solidC. flowingD. gasE. answer not available16. The poisonous gases were not ___ in the air.A. able to floatB. visibleC. able to evaporateD. invisibleE. able to condense17. Scientists analyzed data about Vesuvius in the same way that a zoologist ___ a specimen.A. describes in detailB. studies by cutting apartC. photographsD. chartE. answer not available18. ____have concluded that the volcanic eruption caused a tidal wave.A. Scientist who study oceansB. Scientist who study atmospheric conditionsC. Scientist who study ashD. Scientist who study animal behaviorE. Answer not available in article19. Scientist have used ___water to wash away volcanic ash from the skeletons of victims.A. bottledB. volcanicC. purifiedD. seaE. fountain(三)答案 15. B 16. A 17. B 18. B 19. C阅读(四) 20. Questions 20-24.Conflict had existed between Spain and England since the 1570s. England wanted a share of the wealth that Spain had been taking from the lands it had claimed in the Americas.Elizabeth I, Queen of England, encouraged her staunch admiral of the navy, Sir Francis Drake, to raid Spanish ships and towns. Though these raids were on a small scale, Drake achieved dramatic success, adding gold and silver to England's treasury and diminishing Spain's omnipotence.Religious differences also caused conflict between the two countries. Whereas Spain was Roman Catholic, most of England had become Protestant. King Philip II of Spain wanted to claim the throne and make England a Catholic country again. To satisfy his ambition and also to retaliate against England's theft of his gold and silver, King Philip began to build his fleet of warships, the Armada, in January 1586.Philip intended his fleet to be indestructible. In addition to building new warships, he marshaled one hundred and thirty sailing vessels of all types and recruited more than nineteen thousand robust soldiers and eight thousand sailors. Although some of his ships lacked guns and others lacked ammunition, Philip was convinced that his Armada could withstand any battle with England.The martial Armada set sail from Lisbon, Portugal, on May 9,1588, but bad weather forced it back to port. The voyage resumed on July 22 after the weather became more stable.The Spanish fleet met the smaller, faster, and more maneuverable English ships in battle off the coast of Plymouth, England, first on July 31 and again on August 2. The two battles left Spain vulnerable, having lost several ships and with its ammunition depleted. On August 7, while the Armada lay at anchor on the French side of the Strait of Dover, England sent eight burning ships into the midst of the Spanish fleet to set it on fire. Blocked on one side, the Spanish ships could only drift away, their crews in panic and disorder. Before the Armada could regroup, the English attacked again on August 8.Although the Spaniards made a valiant effort to fight back, the fleet suffered extensive damage. During the eight hours of battle, the Armada drifted perilously close to the rocky coastline. At the moment when it seemed that the Spanish ships would be driven onto the English shore, the wind shifted, and the Armada drifted out into the North Sea. The Spaniards recognized the superiority of the English fleet and returned home, defeated.20.Sir Francis Drake added wealth to the treasury and diminished Spain's ____.A. unlimited powerB. unrestricted growthC. territoryD. treatiesE. answer not available in article21. Philip recruited many ___soldiers and sailors.A. warlikeB. strongC. accomplishedD. timidE. non experienced22. The ____ Armada set sail on May 9, 1588.A. completeB. warlikeC. independentD. isolatedE. answer not available23. The two battles left the Spanish fleet ____.A. open to changeB. triumphantC. open to attackD. defeatedE. discouraged24. The Armada was ___ on one side.A. closed offB. damagedC. aloneD. circledE. answer not available in this article(四 )答案 20. A 21. B 22. B 23. C 24. A(五) 25. Questions 25-29.The victory of the small Greek democracy of Athens over the mighty Persian empire in 490 B. C. is one of the most famous events in history. Darius, king of the Persian empire, was furious because Athens had interceded for the other Greek city-states in revolt against Persian domination. In anger the king sent an enormous army to defeat Athens. He thought it would take drastic steps to pacify the rebellious part of the empire. Persia was ruled by one man.In Athens, however, all citizens helped to rule. Ennobled by this participation, Athenians were prepared to die for their city-state. Perhaps this was the secret of the remarkable victory at Marathon, which freed them from Persian rule. On their way to Marathon, the Persians tried to fool some Greek city-states by claiming to have come in peace. The frightened citizens of Delos refused to believe this. Not wanting to abet the conquest of Greece, they fled from their city and did not return until the Persians had left. They were wise, for the Persians next conquered the city of Etria and captured its people.Tiny Athens stood alone against Persia. The Athenian people went to their sanctuaries. There they prayed for deliverance. They asked their gods to expedite their victory. The Athenians refurbished their weapons and moved to the plain of Marathon, where their little band would meet the Persians. At the last moment, soldiers from Plataea reinforced the Athenian troops.The Athenian army attacked, and Greek citizens fought bravely. The power of the mighty Persians was offset by the love that the Athenians had for their city. Athenians defeated the Persians in archery and hand combat. Greek soldiers seized Persian ships and burned them, and the Persians fled in terror. Herodotus, a famous historian, reports that 6400 Persians died, compared with only 192 Athenians.25 Athens had ____the other Greek city-states against the Persians.A. refused help toB. intervened on behalf ofC. wanted to fightD. given orders for all to fightE. defeated26. Darius took drastic steps to ___ the rebellious Athenians.A. weakenB. destroyC. calmD. placateE. answer not available27. Their participation___to the Athenians.A. gave comfortB. gave honorC. gave strengthD. gave fearE. gave hope28. The people of Delos did not want to ___ the conquest of Greece.A. endB. encourageC. think aboutD. daydream aboutE. answer not available29. The Athenians were ___by some soldiers who arrived from Plataea.A. welcomedB. strengthenedC. heldD. capturedE. answer not available(五)答案 23. C 24. A 25. B 26. C 27. B 28. B 29. B(六) 30. Questions 30-32.The Trojan War is one of the most famous wars in history. It is well known for the ten-year duration, for the heroism of a number of legendary characters, and for the Trojan horse. What may not be familiar, however, is the story of how the war began.According to Greek myth, the strife between the Trojans and the Greeks started at the wedding of Peleus, King of Thessaly, and Thetis, a sea nymph. All of the gods and goddesses had been invited to the wedding celebration in Troy except Eris, goddesses of discord. She had been omitted from the guest list because her presence always embroiled mortals and immortals alike in conflict.To take revenge on those who had slighted her, Eris decided to cause a skirmish. Into the middle of the banquet hall, she threw a golden apple marked or the most beautiful.?All of the goddesses began to haggle over who should possess it. The gods and goddesses reached a stalemate when the choice was narrowed to Hera, Athena, and Aphrodite. Someone was needed to settle the controversy by picking a winner. The job eventually fell to Paris, son of King Priam of Troy, who was said to be a good judge of beauty.Paris did not have an easy job. Each goddess, eager to win the golden apple, tried aggressively to bribe him.捏'll grant you vast kingdoms to rule, ?promised Hera. ast kingdoms are nothing in comparison with my gift,?contradicted Athena. hoose me and I'll see that you win victory and fame in war.?Aphrodite outdid her adversaries, however. She won the golden apple by offering Helen, Zeus' daughter and the most beautiful mortal, to Paris. Paris, anxious to claim Helen, set off for Sparta in Greece.Although Paris learned that Helen was married, he accepted the hospitality of her husband, King Menelasu of Sparta, anyway. Therefore, Menelaus was outraged for a number of reasons when Paris departed, taking Helen and much of the king's wealth back to Troy. Menelaus collected his loyal forces and set sail for Troy to begin the war to reclaim Helen.30 Eris was known for ___both mortals and immortals.A. scheming againstB. involving in conflictC. feeling hostile towardD. ignoringE. comforting31. Each goddess tried ___to bribe Paris. A. boldly B. effectively C. secretly D. carefully E. answer not stated32. Athena ___ Hera, promising Paris victory and fame in war.A. denied the statement ofB. defeatedC. agreed withD. restated the statementE. questioned the statement(六 )答案 30. B 31. A 32. A阅读(七)One of the most intriguing stories of the Russian Revolution concerns the identity of Anastasia, the youngest daughter of Czar Nicholas II. During his reign over Russia, the Czar had planned to revoke many of the harsh laws established by previous czars. Some workers and peasants, however, clamored for more rapid social reform. In 1918 a group of these people, known as Bolsheviks, overthrew the government. On July 17 or 18, they murdered the Czar and what was thought to be his entire family.Although witnesses vouched that all the members of the Czar's family had been executed, there were rumors suggesting that Anastasia had survived. Over the years, a number of women claimed to be Grand Duchess Anastasia. Perhaps the best nown claimant was Anastasia Tschaikovsky, who was also known as Anna Anderson.In 1920, eighteen months after the Czar's execution, this terrified young woman was rescued from drowning in a Berlin river. She spent two years in a hospital, where she attempted to reclaim her health and shattered mind. The doctors and nurses thought that she resembled Anastasia and questioned heer about her background. She disclaimed any connection with the Czar's family.Eight years later, though, she claimed that she was Anastasia. She said that she had been rescued by two Russian soldiers after the Czar and the rest of her family had been killed. Two brothers named Tschaikovsky had carried her into Romania. She had married one of the brothers, who had taken her to Berlin and left her there, penniless and without a vocation. Unable to invoke the aid of her mother's family in Germany, she had tried to drown herself.During the next few years, scores of the Czar's relatives, ex-servants, and acquaintances interviewed her. Many of these people said that her looks and mannerisms were evocative of the Anastasia that they had known. Her grandmother and other relatives denied that she was the real Anastasia, however.Tried of being accused of fraud, Anastasia immigrated to the United States in 1928 and took the name Anna Anderson. She still wished to prove that she was Anastasia, though, and returned to Germany in 1933 to bring suit against her mother's family. There she declaimed to the court, asserting that she was indeed Anastasia and deserved her inheritance.In 1957, the court decided that it could neither confirm nor deny Anastasia's identity. Although we will probably never know whether this woman was the Grand Duchess Anastasia, her search to establish her identity has been the subject of numerous books, plays, and movies.33 Some Russian peasants and workers___for social reform. A. longed B. cried out C. begged D. hopedE. thought much34. Witnesses ___ that all members of the Czar's family had been executed.A. gave assuranceB. thoughtC. hopedD. convinced someE. answer not stated35. Tschaikovsky ____any connection with the Czar's family.A. deniedB. stoppedC. notedD. justifiedE. answer not stated36. She was unable to ___the aid of her relative. A. locate B. speak about C. call upon D. identify E. know37. In court she ___ maintaining that she was Anastasia and deserved her inheritance.A. finally appearedB. spoke forcefullyC. testifiedD. gave evidenceE. answer not stated(七)答案： 32. A 33. B 34. A 35. A 36. C 37. B八) 38. Questions 38-39.King Louis XVI and Queen Marie Antoinette ruled France from 1774 to 1789, a time when the country was fighting bankruptcy. The royal couple did not let France's insecure financial situation limit their immoderate spending, however. Even though the minister of finance repeatedly warned the king and queen against wasting money, they continued to spend great fortunes on their personal pleasure. This lavish spending greatly enraged the people of France. They felt that the royal couple bought its luxurious lifestyle at the poor people's expense.Marie Antoinette, the beautiful but exceedingly impractical queen, seemed uncaring about her subjects; misery. While French citizens begged for lower taxes, the queen embellished her palace with extravagant works of art. She also surrounded herself with artists, writers, and musicians, who encouraged the queen to spend money even more profusely.While the queen's favorites glutted themselves on huge feasts at the royal table, many people in France were starving. The French government taxed the citizens outrageously. These high taxes paid for the entertainments the queen and her court so enjoyed. When the minister of finance tried to stop these royal spendthrifts, the queen replaced him. The intense hatred that the people felt for Louis XVI and Marie Antoinette kept building until it led to the French Revolution. During this time of struggle and violence (1789-1799), thousands of aristocrats, as well as the king and queen themselves, lost their lives at the guillotine. Perhaps if Louis XVI and Marie Antoinette had reined in their extravagant spending, the events that rocked France would not have occurred.38.The people surrounding the queen encouraged her to spend money ____.A. wiselyB. abundantlyC. carefullyD. foolishlyE. joyfully39. The minister of finance tried to curb these royal ___.A. aristocratsB. money wastersC. enemiesD. individualsE. spender(八)答案： 38. B 39. B。

小学上册F卷英语第三单元期中试卷

小学上册英语第三单元期中试卷英语试题一、综合题(本题有100小题，每小题1分，共100分.每小题不选、错误，均不给分)1.I can ______ (对话) in English.2. A ______ (青蛙) has long legs for jumping.3.The _______ can bring joy to your life.4.I love playing games with my ____.5.What is the opposite of ‘day’?A. NightB. MorningC. NoonD. Evening6.What do you use to cut paper?A. ScissorsB. GlueC. TapeD. Ruler7.The capital of Barbados is ________ (布里奇敦).8.The Earth's crust is made up of both continental and ______ components.9.What is the name of the process by which plants release oxygen?A. PhotosynthesisB. RespirationC. GerminationD. Pollination10.The __________ (历史学校教育) helps students learn about their heritage.11.What is the name of the famous clock tower in London?A. Big BenB. Eiffel TowerC. Leaning TowerD. Tower of Pisa答案:A12.What do you call the part of the story where everything is resolved?A. IntroductionB. ClimaxC. ConclusionD. Conflict答案:C13.What do you call the white part of an egg?A. YolkB. ShellC. AlbumenD. Membrane14.The rabbit makes a cozy _________ (窝).15.I like to _____ (draw/color).16.The _____ (star/planet) is bright.17. A dolphin jumps gracefully out of the _______.18. A __________ uses echolocation to navigate.19.We visit the _____ (博物馆).20. A _____ (植物成长) can lead to community beautification.21.The rabbit is very _______ (活泼).22.The flowers smell ___. (sweet)23.Antarctica is covered in __________.24.I play _____ (视频游戏) after homework.25.What is the opposite of 'hot'?A. WarmB. ColdC. CoolD. Heat答案:B26.The __________ (天际线) of the city is amazing.27. A __________ (花圃) can be a peaceful place.28.What is the term for the layer of gases surrounding the Earth?A. AtmosphereB. LithosphereC. HydrosphereD. Biosphere答案:A29.What is the largest ocean on Earth?A. AtlanticB. IndianC. ArcticD. Pacific30.Which instrument has keys and is played by pressing them?A. GuitarB. ViolinC. PianoD. Drum答案:C31. A chemical reaction that occurs without the need for heat is called a _____.32.What do you call the part of the plant that absorbs water and nutrients from the soil?A. StemB. LeafC. RootD. Flower答案:C33.My ________ (玩具名称) is a great way to make new friends.34.My ___ (小狗) greets me at the door.35.I like to watch my ________ (玩具名称) dance.36.The fish is swimming _______ (在水里).37.What do we call the movement of the Earth around the sun?A. RotationB. RevolutionC. OrbitD. Cycle答案:B38.I have a green ______ (植物) in my room. It makes the air feel ______ (清新).39.My favorite hobby is ______ (音乐).40.An object that floats has _______ density than water.41.I like to ________ my friends.42. A vacuum has no ______.43.Heat energy is often absorbed or released during a ______.44.What is the capital of Norway?A. OsloB. BergenC. TrondheimD. Stavanger答案:A45.climate graph) visually represents weather data. The ____46.What is the opposite of 'big'?A. HugeB. SmallC. TallD. Large47.What is the term for a young goat?A. CalfB. KidC. LambD. Foal答案:B48.What is the capital of Sint Maarten?A. PhilipsburgB. Simpson BayC. MarigotD. Cole Bay答案:A49. A ____ swims in the pond and has smooth skin.50.The ______ (植物的形态) can vary greatly.51.I like to play ________ (角色扮演) games with my friends.52.The _____ (狐狸) has a thick, bushy tail.53.The chemical formula for sodium thiocyanate is ______.54.My favorite subject is ______ (英语).55.My mom sings me a ____.56.The dog is ___ in the yard. (running)57.The _____ (袋鼠) hops around in the Australian bush. It is very unique. 袋鼠在澳大利亚灌木丛中跳跃。

稀有气体

氦
• 1868年，法国天文学家简森 (Janssen P J C,1824-1907)在观察日全食时，就曾在太阳光谱上观察到一条黄线D，这和早已知道的钠光谱的D1和D2两条线不相同。同时，英国天文学家洛克耶尔(Lockyer J N,1836-1920)也观测到这条黄线D。当时天文学家认为这条线只有太阳才有，并且还认为是一种金属元素。所以洛克耶尔把这个元素取名为Helium，这是由两个字拼起来的，helio是希腊文太阳神的意思，后缀-ium是指金属元素而言。中译名为氦
谢谢大家
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• 1895年，拉姆赛和另一位英国化学家特拉 1)合作，在用硫酸处理沥青铀矿时，产生一种不活泼的气体，用光谱鉴定为氦，证实了氦元素也是一种稀有气体，这种元素地球上也有，并且是非金属元素。
氪
• 由于氦和氩的性质非常相近，而且它们与周期系中已被发现的其它元素在性质上有很大差异，莱姆赛推测出氦和氩可能是另一族元素，在它们之间一定有一个性质和氦、氩相近的家族。→在1898年5月30 日莱姆赛和特拉弗斯在大量液态空气蒸发后的残余物中，用光谱分析首先发现了比氩重的氪，他们把它命名为Krypton，即隐藏之意。隐藏于空气中多年才被发现
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• 1898年6月，莱姆赛和特拉弗斯在蒸发液态氩时收集了最先逸出的气体，用光谱分析发现了比氩轻的氖。他们把它命名为neon ，源自希腊词neos，意为新，即从空气中发现的新气体。中译名为氖。也就是现在氖灯里的气体。
• 1898年7月12日，莱姆赛和特拉弗斯在分馏液态空气，制得了氪和氖后，又把氪反复地分次萃取，从其中又分出一种质量比氪更重的新气体，他们把它命名为Xenon，源自希腊文xenos，意为陌生人，即为人们所生疏的气体，因为它在空气中的含量极少，仅占总体积的一亿分之八。