a -羟丁酸脱氢酶测定试剂盒(α-酮丁酸底物法)产品技术要求zsbk

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K指数和A指数的由来

K指数和A指数的由来作者：K9LA，翻译：BH4SRCK指数和A指数是两个已知参数，用于预测高纬度电离层对传播的影响（美国国家标准和技术院电台WWV每个整点后18分钟会播报这两个指数的值）。

下面我们就来深入研究下K指数和A指数，以便更好的理解这两个传播参数。

我们先从K指数说起，K指数是地球磁场相对于平静日状况下3小时的磁场变化值。

K指数的值用磁力计测量，单位是毫伏特斯拉（nT）。

表一给出了nT和在中纬度地区博尔多的磁力计测量的K指数值之间的对应关系表1 博尔多nT 与K 的对应关系如果我们用nT对应范围的中值给nT和K指数值画一条对应关系图，则可以得到如图一所示的图图 1需要注意的是如果nT的值以对数值标示的话，图中的曲线则会变成一条近似的直线。

由于其并不是一条直线，因此我们认为K指数值具有准对数性。

在谈论下个话提前，注意下这个说明。

就是每个测量台都有自己的nT和K指数值的公差表。

这么做是为了让每个测量台K指数值能够表示相同程度的扰乱。

对于某个给定的扰乱，地球磁场的变化在高纬度地区的变化值最大，因此位于阿拉斯加的学院台测量的K指数值为9时，对应的磁场变化值要大于2500nT。

而位于低纬度地区苏门答腊的嘅珀台测到的K指数值为9时，其对应的磁场变化值则为大于300nT。

这两个值可以和位于中纬度地区博尔多台测得K指数值为9时，对应的磁场变化值作对比，见表一。

我们再来看看磁力计的记录值，也叫做磁强记录图，看看K指数值是如何确定的。

图2是博尔多站2003年4月16日的磁强记录图的快照。

（感谢美国国家大洋和气候管理局空间环境中心的克里斯托弗.鲍尔奇博士提供）。

Figure 2 博尔多台磁强记录图图中上部的实线表示的是磁场的H成分，即磁场水平矢量成分的变化。

实线下方的点线表示的是地球磁场处于平静日时的H成分曲线图。

图中下部的实线表示的是磁场的D分量，即磁场的磁偏角值的变化。

和这条实线几乎重复的点线，表示的是地球磁场平静日时的D分量值。

新编英语教程6unit 4 A red light for scofflaws

Examples Statistics red-light runner Para. 4 The most flagrant scofflaw is the ________________. Examples Quotation
III. (Para. 5-8) Dangers of scofflaws Para. 5 The flouting of basic rules harms society because respect scofflaws show no ____________ to the social rules and contempt display ______________ for the fundamentals of order. Para. 6 Today scofflawry is pervasive and represents the elementary social demoralization _________________________________________. Example Para. 7 The scofflawry is not only a matter of etiquette. It may violent crimes lead to _____________________________. Examples
P2
abound: v. be plentiful (l. 11) e.g. Rumors abound as to the reason for his resignation. Sarcasm abounds in “Fortress Besieged”. flurry: abundance, great quantity pass around: offer flagrant: notorious What does “hello, Everybody” mean?

阿兹夫定片Azvudine Tablets-详细说明书与重点

阿兹夫定片Azvudine Tablets 【汉语拼音】Azifuding Pian【成份】本品主要成份为阿兹夫定。

化学名称：1-(4-叠氮-2-脱氧-2-氟-β-D-呋喃核糖基)胞嘧啶，化学结构式：分子式：C9H11FN6O4，分子量：286.22【性状】本品为白色或类白色片。

【适应症】与核苷逆转录酶抑制剂及非核苷逆转录酶抑制剂联用，用于治疗高病毒载量（HIV-1 RNA≥100000 copies/ml）的成年HIV-1感染患者。

【规格】（1）1mg （2）3mg【用法用量】HIV-1感染患者的初始治疗应由有治疗HIV感染经验的医师进行。

为确保给药剂量，片剂应整片吞服，不可碾碎。

本品推荐剂量为成年患者每次3mg，每日1次，于睡前空腹口服。

【不良反应】本说明书描述了在临床试验中观察到的判断为可能由阿兹夫定片引起的不良反应的发生率。

由于各临床试验开展条件不同，因此不同试验中的不良反应发生率无法相互进行比较，也可能不能反映临床实践中的实际发生率。

在本品的 I、II 期临床开发项目中一共有 295 名受试者（244 名 HIV 感染受试者和 51 名健康受试者）至少接受了 1 个剂量的阿兹夫定治疗或给药。

研究结果提示，阿兹夫定片在 HIV感染者中 1mg~5mg单次给药是安全耐受的，出现的不良反应均为轻度，主要表现为发热、头晕、恶心、腹泻等，且均为目前已上市同类抗 HIV 药物已报道的不良反应，经过药物对症治疗或不经治疗均能恢复正常。

本品安全性数据主要来自于一项在未接受过抗 HIV 病毒治疗的感染者中进行的关键性 II 期临床研究，对比阿兹夫定 2mg、3mg、4mg 每日一次与拉米夫定（3TC），四者分别联合固定剂量富马酸替诺福韦二吡呋酯（TDF）+依非韦伦（EFV）疗法。

给药 48 周期间，发生的不良反应均为已上市抗 HIV 药物常见不良反应，主要为头晕、丙氨酸氨基转移酶升高、γ-谷氨酰转移酶升高、天门冬氨酸氨基转移酶升高，严重程度主要为 1~2 级，阿兹夫定各组间不良反应发生率与对照组 3TC 相近。

A+医学百科,在线医学百科全书

A+医学百科,在线医学百科全书症状查询点击部位名称可查询更多相关疾病全⾝败⾎症抽搐创伤低⾎压恶寒发热寒战乏⼒昏迷肌⾁酸痛淋巴结肿⼤贫⾎⽪肤?盗汗冻疮多汗症鳞屑玫瑰疹疱疹⽪肤⼲燥丘疹雀斑瘙痒湿疹紫绀头部? (眼 | ⽿ | ⿐ | ⼝) 头痛头晕畏光眼疲劳⽿鸣⽿痛⿐出⾎⿐塞咳嗽⼝⼲⽛痛颈部喉头⽔肿甲状腺肿⼤落枕吞咽困难胸部呼吸困难咳⾎咯⾎⽓喘乳房肿块乳头内陷⼼悸⼼绞痛⼼律失常胸闷胸痛窒息背部脊柱弯曲椎间盘脱出腹部便秘恶⼼反胃腹痛腹泻腹胀痢疾脾肿⼤⾷欲不振胃痛消化不良厌⾷腰部尿急尿痛肾病综合征腰背痛腰椎间盘突出臀部便⾎肛裂肛门瘙痒脱肛盆腔尿频尿失禁尿⾎少尿⽆尿遗尿⽺⽔过多⽣殖部位⽩带闭经痛经宫颈糜烂流产性交疼痛性欲减退遗精睾丸疼痛睾丸萎缩四肢单瘫肝掌鸡眼抽筋静脉曲张⼿⾜皲裂乏⼒⼩腿溃疡肘关节脱位症状查询点击部位名称可查询更多相关疾病全⾝败⾎症抽搐创伤低⾎压恶寒发热寒战乏⼒昏迷肌⾁酸痛淋巴结肿⼤贫⾎⽪肤?盗汗冻疮多汗症鳞屑玫瑰疹疱疹⽪肤⼲燥丘疹雀斑瘙痒湿疹紫绀头部? (眼 | ⽿ | ⿐ | ⼝) 头痛头晕畏光眼疲劳⽿鸣⽿痛⿐出⾎⿐塞咳嗽⼝⼲⽛痛颈部喉头⽔肿甲状腺肿⼤落枕吞咽困难胸部呼吸困难咳⾎咯⾎⽓喘乳房肿块乳头内陷⼼悸⼼绞痛⼼律失常胸闷胸痛窒息背部脊柱弯曲椎间盘脱出腹部便秘恶⼼反胃腹痛腹泻腹胀痢疾脾肿⼤⾷欲不振胃痛消化不良厌⾷腰部尿急尿痛肾病综合征腰背痛腰椎间盘突出臀部便⾎肛裂肛门瘙痒脱肛盆腔尿频尿失禁尿⾎少尿⽆尿遗尿⽺⽔过多⽣殖部位⽩带闭经痛经宫颈糜烂流产性交疼痛性欲减退遗精睾丸疼痛睾丸萎缩四肢单瘫肝掌鸡眼抽筋静脉曲张⼿⾜皲裂乏⼒⼩腿溃疡肘关节脱位。

第三章群论的应用(A)

O 原子的轨道 2s 2pz 2px 2py
H 原子的轨道 -1
(2) 2 (1sa +1sb )
—
-1
(2) 2 (1sa 1sb )
分子轨道 1a1,2a1,3a1
1b1 1b2, 2b2
分子的能级图概括于图3.1.2所示
图3.1.2 H2O 分子能级图概况
由图可见，有两个成键轨道(1a1和1b2)，两个实际上是非键轨道(2a1 和1b1)。这四个轨道均填满电子，其基态的电子组态为
+1sb
1sc
1sd
)
3.1.15
方程3.1.11+3.1.13=
1 2
(1sa
1sb
+1sc
1sd
)
3.1.16
方程3.1.11+3.1.14=
1 2
(1sa
1sb
1sc
+1sd
)
3.1.17
由方程3.1.11到3.1.14组合得到具有T2对称性的三者组合可以有许多途径，这里选择的一种是由方程3.1.15到3.1.17分别和C 原子的2pz，2px和2py轨道有效的叠加的函数，如图3.1.7所示。
=4(1sa +1sb +1sc ) (3)1/2 (1sa +1sb +1sc ) (归一化之后)
3.1.5
PE' (1sa )=2(1sa ) 1(1sb +1sc )+2(1sa ) 1(1sb +1sc )
=4(1sa ) 2(1sb +1sc )
(6)1/2[2(1sa ) 1sb 1sc ] (归一化之后)
对于具有oh对称性的八面体羰基配合物mco6则为由于羰基配合物的结构和co伸缩振动谱带的数目间有着直接的联系当用群论方法对每个可能的结构计算出羰基配合物中co伸缩谱带的数目并和它们的光谱进行比较通常可以直接推断在配合物中co基团的排列

全新版大学英语第三册 unit 4 Was Einstein a Space Alien

To relax, he revolutionized physics. In 1905, at the age of 26 and four years before he was able to get a job as a professor of physics, Einstein published five of the most important papers in the history of science — all written in his “spare time.” He proved that atoms and molecules existed. Before 1905, scientists weren’t sure about that. He argued that light came in little bits (later called “photons”) and thus laid the foundation for quantum mechanics. He described his theory of special relativity: space and time were threads in a common fabric, he proposed, which could be bent, stretched and twisted.
Walking briskly to the Patent Office, where he was a “Technical Expert, Third Class,” Albert worried about his mother. She was getting older and frail, and she didn’t approve of his marriage to Mileva. Relations were strained. Albert glanced at a passing shop window. His hair was a mess; he had forgotten to comb it again. Work. Family. Making ends meet. Albert felt all the pressure and responsibility of any young husband and father.

维生素A的合成方法

CH3
OH
CH2Cl2
CH3
OH H3C
OCOCH3
反应机理
CH3 CH 3 CH3
CH3COCl
+
N N
+
CH3 Cl
OH H3C
OH
COCH3
CH3 CH 3 O H3C N HOR +
+
CH3
+
n
CH3
OH H3C
OCOCH3
N Cl H
+
第六步：第六步：羟基溴化和脱溴化氢
CH3 CH 3 CH3
CH3
C
OMgBr
CH3
CH3 CH 3
CH3 BrMg CHO
C
OMgBr CH3 CH3
CH3 C OMgBr
C
OMgBr
CH3 CH3 CH 3 CH3 C OH C
CH3 OH
CH3
水解 NH4Cl
CH3
第四步：第四步：选择性氢化
CH3 CH3 CH 3 CH3 C OH C OH
Pd-CaCO3 喹啉 H2
维生素A醋酸酯的合成维生素醋酸酯的合成
CH3 CH 3 CH3 O CH3
CH3 CH H C 3 3 O 3
C C OH OH
C HC CH3 OH
ClCH2COOCH3 CH3ONa
CH3 CH 3
1)NaOH 2)HOAc
CH3
EtMgBr
CH3 CHO
CH3 CH 3
CH3 COOH O
水解
H
+
CH3
脱羧 OH-
CH3 CH 3
CH3
第三步：第三步：格式反应

Agilent 34970A介绍

选择以下选项之一：“None（无）”（8 个数据位，出厂设置）、“Even（偶数）” （7 个数据位）或“Odd （奇数）” （7 个数据位）。设置奇偶时，您 EVEN,7 BIST 还可以间接设置数据位数。
三.儀器的使用
1.执行一次全面自检。 SHIFT 全面自检的内容比接通电源时自检的内容更多。请在打开仪器时按住 ,始终按住该键，直到听到一声很长的蜂鸣声为止。当您在听到蜂鸣声之后松开该键时，仪器开始自检。 2.將導線連接到模塊
4.标定配置菜单
8 高级测量／实用程序菜单
12. 移位／本地键
多个前面板键将指导您通过菜单完成对该仪器不同参数的配置，以下步骤将使用Sto/Rel 键展示菜单结构。
1. 按菜单键。您将自动转到菜单的第一级，旋转旋钮可以查看菜单第一级中的其他选项，该菜单在约 20 秒钟内处于非活动状态之后将自动超时，您将返回到进入该菜单之前所进行的操作。
Measure 使用旋钮滚动浏览每级菜单中的测量选项。当您按进行选择时，该菜单将自动指导您完成配置所选功能测量的所有相关选项。配置完参数之后，您将自动退出该菜单。当前选项（或默认选项）将以全亮方式显示，这样易于识别。当您选择另一选项时，新选项将以全亮方式显示，并成为默认选项。选项顺序始终保持不变。但是，備注：该菜单处于非活动状态约 20 秒钟后将超时，先前所做的任何更改均会您总是可以在每个参数的当前（以全亮方式显示）设置中进入该菜單。生效。
（3）运行扫描并将读数存储在非易失性存储器中。
（4）查看扫描数据。
5.关闭通道。
GPIB/488 Sto/Rcl 2 選擇GPIB 地址
您可以將儀器的地址設置為0至30之間的任一值，出廠設置的地址為”9” ADDRESS 09 Sto/Rcl 3 保存所做更改并退出菜單

ICC协会货物保险A条款

INSTITUTE CARGO CLAUSES (A)RISKS COVERED1. This insurance covers all risks of loss of or damage to thesubject-matter insured except as provided in Clauses 4, 5, 6 and 7 below,(General Average Clause)2. This insurance covers general average and salvage charges, adjustedor determined according to the contract of affreightment and/or thegoverning law and practice, incurred to avoid or in connection with theavoidance of loss from any cause except those excluded in Clauses 4, 5,6 and7 or elsewhere in this insurance.("Both to Blame Collision"Clause)3. This insurance is extended to indemnify the Assured against suchproportion of liability under the contract of affreightment "Both toBlame Collision"Clause as is in respect of a loss recoverable hereunder.In the event of any claim by shipowners under the said Clause the Assuredagree to notify the Underwriters who shall have the right, at their owncost expense, to defend the Assured against such claim.(General Exclusions Clause)EXCLUSIONS4. In no case shall this insurance cover4.1 loss damage or expense attributable to wilful misconduct of theAssured4.2 ordinary leakage, ordinary loss in weight or volume, or ordinary wearand tear of the subject-matter insured4.3 loss damage or expense caused by insufficiency or unsuitability ofpacking or preparation of the subject-matter insured (for the purposeof this Clause 4.3 "packing" shall be deemed to include stowage in acontainer or liftvan but only when such stowage is carried out prior toattachment of this insurance or by the Assured or their servants)4.4 loss damage or expense caused by inherent vice or nature of thesubject-matter insured4.5 loss damage or expense proximately caused by delay, even though thedelay be caused by a risk insured against (except expenses payable underClause 2 above)4.6 loss damage or expense arising from insolvency or financial defaultof the owners managers charterers or operators of the vessel4.7 loss damage or expense arising from the use of any weapon of waremploying atomic or nuclear fission and/or other like reaction orradioactive force or matter.（Unseaworthiness and Unfitness Exclusion Clause）5 5.1 In no case shall this insurance cover loss damage or expense arisingfromunseaworthiness of vessel or craft.unfitness of vessel craft conveyance container or liftvan for the safe carriage of the subject-matter insured.where the Assured or their servants are privy to such unseaworthiness or unfitness, at the time the subject-matter insured is loaded therein.5.2 The Underwriters waive any breach of the implied warranties ofseaworthiness of the ship and fitness of the ship to carry thesubject-matter insured to destination, unless the Assured or theirservants are privy to such unseaworthiness or unfitness.(War Exclusion Clause)6 In no case shall this insurance cover loss damage or expense causedby6.1 war civil war revolution rebellion insurrection, or civil strifearising therefrom, or any hostile act by or against a belligerent power6.2 capture seizure arrest restraint or detainment (piracy excepted),and the consequences thereof or any attempt thereat.6.3 derelict mines torpedoes bombs or other derelict weapons of war.(Strikes Exclusion Clause)7 In no case shall this insurance cover loss damage or expense7.1 caused by strikers, locked-out workmen, or persons taking part inlabour disturbances, riots or civil commotions7.2 resulting from strikes, lock-outs, labour disturbances, riots orcivil commotions7.3 caused by any terrorist or any person acting from a political motive.(Transit Clause)DURATION8 8.1 This insurance attaches from the time the goods leave the warehouseor place of storage at the place named herein for the commencement of the transit, continues during the ordinary course of transit andterminates either8.1.1 on delivery to the Consignees' or other final warehouse or placeof storage at the destination named herein8.1.2 on delivery to any other warehouse or place of storage, whetherprior to or at the destination named herein, which the Assured elect to use either8.1.2.1 for storage other than in the ordinary course of transit or8.1.2.2 for allocation or distribution.or8.1.3 on the expiry of 60 days after completion of discharge over sideof the goods hereby insured from the oversea vessel at the final port of discharge.Whichever shall first occur.8.2 If, after discharge over side from the oversea vessel at the final port of discharge, but prior to termination of this insurance, the goods are to be forwarded to destination other than that to which they are insured hereunder, this insurance, whilst remaining subject to termination as provided for above, shall not extend beyond the commencement of transit to such other destination.8.3 This insurance shall remain in force (subject to termination as provided for above and to the provisions of Clause 9 below) during delay beyond the control of the Assured, any deviation, forced discharge, reshipment or transshipment and during any variation of the adventure arising from the exercise of a liberty granted to ship owners or charterers under the contract of affreightment.(Termination of Contract of Carriage Clause)9 If owing to circumstances beyond the control of the Assured either the contract of carriage is terminated at a port or place other than the destination named therein or the transit is otherwise terminated before delivery of the goods as provided for in Clause 8 above, then this insurance shall also terminate unless prompt notice is given to the Underwriters and continuation of cover is requested when the insurance shall remain in force, subject to an additional premium if required by the Underwriters, either9.1 until the goods are sold and delivered at such port or place, or, unless otherwise specially agreed, until the expiry of 60 days after arrival of the goods hereby insured at such port or place, whichever shall first occur,or9.2 If the goods are forwarded within the said period of 60 days (or any agreed extension thereof) to the destination named herein or to any other destination, until terminated in accordance with provisions of Clause 8 above.(Change of Voyage Clause)10 Where, after attachment of this insurance, the destination is changed by the Assured, held covered at a premium and on conditions to be arranged subject to prompt notice being to the Underwriters.(Insurable Interest Clause)CLAIMS11 11.1 In order to recover under this insurance the Assured must have an insurable interest in the subject-matter insured at the time of the loss.11.2 Subject to 11.1 above, the Assured shall be entitled to recover for insured loss occurring during the period cover by this insurance, notwithstanding that the loss occurred before the contract of insurance was concluded, unless the Assured were aware of the loss and the Underwriters were not.(Forwarding Charge Clause)12 Where, as a result of the operation of a risk covered by this insurance,the insured transit is terminated at a port or place other than that to which the subject-matter is covered under this insurance, theUnderwriters will reimburse the Assured for any extra charges properly and reasonably incurred in unloading storing and forwarding thesubject-matter to the destination to which it is insured hereunder.This Clause 12 which does not apply to general average or salvage charges, shall be subject to the exclusions contained in Clauses 4, 5, 6 and 7 above, and shall not include charges arising from the fault negligence insolvency or financial default of the Assured or their servants.(Constructive Total Loss)13 No claim for Constructive Total Loss shall be recoverable hereunderunless the subject-matter insured is reasonably abandoned either on account of its actual total loss appearing to be unavoidable or because the cost of recovering, reconditioning and forwarding the subject-matter to be destination to which it is insured would exceed its value onarrival.(Increased Value Clause)14 14.1 If any Increased Value insurance is effected by the Assured onthe cargo insured herein the agreed value of the cargo shall be deemed to be increased to the total amount insured under this insurance and all Increased Value insurance covering the loss and liability under this insurance shall be in such proportion as the sum insured herein bears to such total amount insured.In the event of claim the Assured shall provide the Underwriters with evidence of the amounts insured under all other insurances.14.2 Where this insurance is on Increased Value the following clauseshall apply:The agreed value of the cargo shall be deemed to be equal to the total amount insured under the primary insurance and all Increased Valueinsurance covering the loss and effected on the cargo by the Assured, and liability under this insurance shall be in such proportion as the sum insured herein bears to such total amount insured.In the event of claim the Assured shall provide the Underwriters with evidence of the amounts insured under all other insurances.(Not to inure Clause)BENEFIT OF INSURANCE15 This insurance shall not insure to the benefit of the carrier or other bailee.(Duty of Assured Clause)MINIMISING LOSSES16 It is the duty of the Assured and their servants and agents in respect of loss recoverable hereunder16.1 to take such measures as may be reasonable for the purpose of averting or minimizing such loss,and16.2 to ensure that all rights against carriers, bailees or other third parties are properly preserved and exercised and the Underwriters will, in addition to any loss recoverable hereunder, reimburse the Assured for any charges properly and reasonably incurred in pursuance of these duties.(Waiver Clause)17 Measures taken by the Assured or the Underwriters with the object of saving, protecting or recovering the subject-matter insured shall not be considered as a waiver or acceptance of abandonment or otherwise prejudice the rights of either party(Reasonable Dispatch Clause)AVOIDANCE OF DELAY18 It is a condition of this insurance that the Assured shall act with reasonable dispatch in all circumstances within their control. (English Law and Practice Clause)LAW AND PRACTICE19 This insurance is subject to English law and practice.。

INTERNATIONAL JOURNAL OF WIRELESS AND MOBILE COMPUTING (IJWMC) 1 A Biologically Inspired Qo

A Biologically Inspired QoS Routing Algorithm forMobile Ad Hoc NetworksZhenyu Liu,Marta Z.Kwiatkowska,and Costas ConstantinouAbstract—This paper presents an Emergent Ad hoc Routing Algorithm with QoS provision(EARA-QoS).This ad hoc QoS routing algorithm is based on a swarm intelligence inspired routing infrastructure.In this algorithm,the principle of swarm intelligence is used to evolutionally maintain routing information. The biological concept of stigmergy is applied to reduce the amount of control trafﬁc.This algorithm adopts the cross-layer optimisation concept to use parameters from different layers to determine routing.A lightweight QoS scheme is proposed to provide service-classiﬁed trafﬁc control based on the data packet characteristics.The simulation results show that this novel routing algorithm performs well in a variety of network conditions.Index Terms—MANET,routing,QoS,swarm intelligence.I.I NTRODUCTIONM OBILE ad hoc networks(MANETs)are wireless mo-bile networks formed munication in such a decentralised network typically involves temporary multi-hop relays,with the nodes using each other as the relay routers without anyﬁxed infrastructure.This kind of network is veryﬂexible and suitable for applications such as temporary information sharing in conferences,military actions and disaster rescues.However,multi-hop routing,random movement of mobile nodes and other features unique to MANETs lead to enormous overheads for route discovery and maintenance.Furthermore, compared with the traditional networks,MANETs suffer from the resource constraints in energy,computational capacities and bandwidth.To address the routing challenge in MANETs,many ap-proaches have been proposed in the literature.Based on the routing mechanism for the traditional networks,the proactive approaches attempt to maintain routing information for each node in the network at all times[1]–[3],whereas the reactive approaches onlyﬁnd new routes when required[4]–[6].Other approaches make use of geographical location information for routing[7],[8].Those previous works only provide a basic “best effort”routing functionality that is sufﬁcient for con-ventional applications such asﬁle transfer or email download. To support real-time applications such as V oIP and video stream in MANETs,which have a higher requirement for delay,jitter and packet losses,provision of Quality-of-Service (QoS)is necessary in addition to basic routing functionality. Z.Liu and M.Z.Kwiatkowska is with School of Computer Science,The University of Birmingham,Birmingham,England B152TT.C.Constantinou is with the Department of Electronic Electrical and Computer Engineering,The University of Birmingham,Birmingham,England B152TT.Given the nature of MANETs,it is difﬁcult to support real-time applications with appropriate QoS.In some cases it may be even impossible to guarantee strict QoS requirements.But at the same time,QoS is of great importance in MANETs since it can improve performance and allow critical information to ﬂow even under difﬁcult conditions.At present,the most fundamental challenges of QoS support in MANETs concern how to obtain the available bandwidth and maintain accurate values of link state information during the dynamic evolution of such a network[9].Based on common techniques for QoS provision in the Internet,some researchers proposed the integration of QoS provision into the routing protocols[10],[11].However,since these works implicitly assumed the same link concept as the one in wired networks,they still do not fully address the QoS problem for MANETs.In this paper,we propose a new version of the self-organised Emergent Ad hoc Routing Algorithm with QoS provisioning(EARA-QoS).This QoS routing algorithm uses information from not only the network layer but also the MAC layer to compute routes and selects different paths to a destination depending on the packet characteristics.The underlying routing infrastructure,EARA originally proposed in[12],is a probabilistic multi-path algorithm inspired by the foraging behaviour of biological ants.The biological concept of stigmergy in an ant colony is used for the interaction of local nodes to reduce the amount of control trafﬁc.Local wireless medium information from the MAC layer is used as the artiﬁcial pheromone(a chemical used in ant communications) to reinforce optimal/sub-optimal paths without the knowledge of the global topology.One of the optimisations of EARA-QoS over EARA is the use of metrics from different layers to make routing decisions. This algorithm design concept is termed as the cross-layer design approach.Research[13]has shown the importance of cross-layer optimisations in MANETs,as the optimisation at a particular single layer might produce non-intuitive side-effects that will degrade the overall system performance.Moreover, the multiple-criteria routing decisions allow for the better usage of network characteristics in selecting best routes among multiple available routes to avoid forwarding additional data trafﬁc through the congested areas,since the wireless medium over those hotspots is already very busy.The parameters for measuring wireless medium around a node depend largely on the MAC layer.In this paper,we focus on the IEEE802.11 DCF mode[14],since it is the most widely used in both cellular wireless networks and in MANETs.This cross-layer technique of using MAC layer information can be appliedeasily to other MAC protocols.In addition to the basic routing functionality,EARA-QoS supports an integrated lightweight QoS provision scheme.In this scheme,trafﬁc ﬂows are classiﬁed into different service classes.The classiﬁcation is based on their relative delay bounds.Therefore,the delay sensitive trafﬁc is given a higher priority than other insensitive trafﬁc ﬂows.The core technique of the QoS provision scheme is a token bucket queuing scheme,which is used to provide the high priority to the real-time trafﬁc,and also to protect the lower-priority trafﬁc from star-vation.Experimental results from simulation of mobile ad hoc networks show that this QoS routing algorithm performs well over a variety of environmental conditions,such as network size,nodal mobility and trafﬁc loads.II.B ACKGROUNDIn this section,we give a brief introduction to background knowledge on ant colony heuristics,and the QoS provision techniques in MANETs.A.Foraging Strategies in AntsOne famous example of biological swarm social behaviour is the ant colony foraging [15](see Figure 1).Many ant species have a trail-laying,trail-following behaviour when foraging:individual ants deposit a chemical substance called pheromone as they move from a food source to their nest,and foragers follow such pheromone trails.Subsequently,more ants are attracted by these pheromone trails and in turn reinforce them even more.As a result of this auto-catalytic effect,the optimal solution emerges rapidly.In this food searching process a phenomenon called stigmergy plays a key role in developing and manipulating local information.It describes the indirect communication of individuals through modifying theenvironment.Fig.1.All Ants Attempt to Take the Shortest PathFrom the self-organisation theory point of view,the be-haviour of the social ant can be modelled based on four elements:positive feedback,negative feedback,randomness and multiple interactions [16].This model of social ants using self-organisation theories provides powerful tools to transfer knowledge about the social insects to the design of intelligent decentralised problem-solving systems.B.Quality-of-Service in MANETsQuality-of-Service (QoS)provision techniques are used to provide some guarantee on network performance,such as average delay,jitter,etc.In wired networks,QoS provision can generally be achieved with the over-provisioning of re-sources and with network trafﬁc engineering [17].With the over-provisioning approach,resources are upgraded (e.g.ﬁbre optic data link,advanced routers and network cards)to make networks more resistant to resource demanding applications.The advantage of this approach is that it is easy to be implemented.The main disadvantage of this approach is that all the applications still have the same priority,and the network may become unpredictable during times of bursting and peak trafﬁc.In contrast,the idea of the trafﬁc engineering approach is to classify applications into service classes and handle each class with a different priority.This approach overcomes the defect of the former since everyone is following a certain rule within the network.The trafﬁc engineering approach has two complemen-tary means to achieve QoS provisioning,Integrated Services (IntServ)and Differentiated Services (DiffServ).IntServ [18]provides guaranteed bandwidth for ﬂows,while DiffServ [19]provides hard guarantees for service classes.Both of the approaches rely on the possibility to make bandwidth reservations.The former was used in ATM (Asynchronous Transfer Mode)[20]and is today the method of achieving QoS in RSVP-IntServ [21].On the other hand,in the DiffServ approach,no reservation is done within the network.Instead,QoS is achieved by mechanisms such as Admission Control ,Policy Manager ,Trafﬁc Classes and Queuing Schedulers .These mechanisms are used to mark a packet to receive a particular forwarding or dropping treatment at each node.Based on QoS provision techniques in wired networks,many QoS approaches are proposed to provide QoS services for MANETs.Flexible QoS Model for MANETs (FQMM)[22],is the ﬁrst QoS approach for MANETs,which combines knowledge on IntServ/DiffServ in wired networks with con-sideration of MANETs.As an essential component to achieve the QoS provisioning,QoS routing algorithms tightly integrate QoS provisioning into routing protocols.The QoS version of AODV (QoS-AODV)[23],the Core-Extraction Distributed Ad Hoc Routing (CEDAR)protocol [10],the Multimedia Support for Mobile Wireless Networks (MMWN)protocol [11],and the ticket-based protocols [24]are examples of QoS routing algorithms proposed for MANETs.On the other hand,QoS signaling techniques are inde-pendent of the underlying routing protocols.The In-band Signalling for QoS in Ad-Hoc Mobile Networks (INSIGNIA)algorithm [25]is the typical signaling protocol designed exclusively for MANETS.The idea of CEDAR,MMWN,and ticket-based protocols is to disseminate link-state information across the network in order to enable other nodes to ﬁnd routes that meet certain QoS criteria,like the minimum bandwidth.On the other hand,INSIGNIA piggybacks resource reservations onto data packets,which can be modiﬁed by intermediate nodes to inform the communication endpoint nodes in case of lack ofresources.All those approaches are based on the idea that the wireless links between mobile nodes have certain QoS related properties,in particular a known amount of available bandwidth,and that nodes are able to give guarantees for trafﬁc traversing these links.III.C RITIQUE OF E XISTING Q O S A PPROACHES INMANET SNowadays,most of the QoS provisioning techniques are derived from the QoS approaches of the wired networks. However,QoS support approaches proposed in wired networks are based on the assumption that the link characteristics such as bandwidth,delay,loss rate and error rate must be available and manageable.However,given the challenges of MANETs, e.g.dynamic topology and time-varying link capacity,this assumption does not apply any longer.Thus,applying the concepts of wired trafﬁc engineering QoS approaches directly to MANETs is extremely difﬁcult.Generally,the situation in MANETs is completely different from those in wired networks.In wireless networks,the available bandwidth undergoes fast time-scale variations due to channel fading and errors from physical obstacles.These effects are not present in wired networks.In MANETs,the wireless channel is a shared-access medium,and the available bandwidth even varies with the number of hosts contending for the channel.Below we analyse why the IntServ/DiffServ models are not appropriate for MANETs respectively. IntServ based approaches are not applicable for MANETs mainly due to two factors,huge resource consumption and computation power limitation.Firstly,to support IntServ,a huge amount of link state information has to be built and main-tained for each mobile node.The amount of state information increases proportionally with the number ofﬂows,which is also a problem with the current IntServ QoS scheme.Secondly, current wireless networks employ two major MAC techniques, the single-channel approach and the multiple channel ap-proach.With single-channel approach(e.g.IEEE802.11[14]), all nodes share the same channel and therefore potentially interfere with each other.With a multiple-channel approach (e.g.Bluetooth[26]or CDMA[27]),nodes can communicate on several channels simultaneously.Both of the two MAC techniques have a similar bandwidth reservation mechanism. This common mechanism requires a transmission schedule to deﬁne time slots,in which nodes take their turns periodically. For each slot,its duration and a set of possible simultaneous transmissions must be deﬁned.However,in wireless networks, the problem ofﬁnding an optimal schedule is proved to be NP-complete[28],which is a fundamental limitation of QoS provisioning in wireless networks.On the other hand,the DiffServ approach is a lightweight QoS model for interior routers since individual stateﬂows are aggregated into sets of service classes whose packets are treated differently at the routing nodes.This makes routing a lot easier in the network.Thus this approach could be a potential solution for MANETs.Even though it is not practical to provide a hard separation of different service classes in MANETs,relative prioritisation is possible in such a way that trafﬁc of a certain class is given a higher or lower priority than trafﬁc of other service classes.One solution would be to divide the trafﬁc into a predeﬁned set of service classes that are deﬁned by their relative delay bounds,such as delay sensitive(realtime)and insensitive(bulk)trafﬁc.Realtime trafﬁc should be given higher priority than bulk trafﬁc.No absolute bandwidth guarantees are provided.Some work based on service differentiation rather than resource reservations in MANETs already exists[29].IV.D ESCRIPTION OF EARA-Q O SEARA-QoS is an on-demand multipath routing algorithm for MANETs,inspired by the ant foraging intelligence.This algorithm incorporates positive feedback,negative feedback and randomness into the routing computation.Positive feed-back originates from destination nodes to reinforce the existing pheromone on good paths.Ant-like packets,analogous to the ant foragers,are used to locallyﬁnd new paths.Artiﬁcial pheromone is laid on the communication links between nodes and data packets are biased towards strong pheromone,but the next hop is chosen probabilistically.To prevent old routing solutions from remaining in the current network status,expo-nential pheromone decay is adopted as the negative feedback. Each node using this algorithm maintains a probabilistic routing table.In this routing table,each route entry for the destination is associated with a list of neighbour nodes.A probability value in the list expresses the goodness of node as the next hop to the destination.For each neighbour, the shortest hop distance to the destination and the largest sequence number seen so far are also recorded.In addition to the routing table,each node also possesses a pheromone table.This table tracks the amount of pheromone on each neighbour link.The table may be viewed as a ma-trix with rows corresponding to neighbourhood and columns to destinations.There are three threshold values controlling the bounds on pheromone in the table.They are the upper pheromone that prevents extreme differences in pheromone, the lower pheromone,below which data trafﬁc cannot be forwarded,and the initial pheromone that is assigned when a new route is found.In addition to the routing data structures present above,the following control packets are used in EARA-QoS to perform routing computation:Route Request Packet(RQ)containing destination ad-dress,source address and broadcast ID.Route Reply Packet(RP)containing source address,des-tination address,sequence number,hop account and life-time.Reinforcement Signal(RS)containing destination ad-dress,pheromone value and sequence number.Local Foraging Ant(LFA)containing source address (the node that sent LFA),the least hop distance from the source to the destination,stack of intermediate node address and hop count.Hello Packet(HELLO)containing source(the node that sent Hello)address and hop count(set to0).A.Parameters of Lower Layers1)The Average MAC Layer Utilisation:Theﬁrst metric is the average MAC layer utilisation for a node.This metric measures the usage of the wireless medium around that node. As the instantaneous MAC layer utilisation at a node is either (busy)or(idle),we average this value over a period of time window as follows:(1) where is the time when the medium is busy in the window.This average MAC utilisation indicates the degree to which the wireless medium around that node is busy or idle.We consider the instantaneous MAC layer utilisation level at a node to be1when the wireless medium around that node either detects physical carrier to be present or is deferring due to virtual carrier sensing,inter-frame spacing,or backoff.In addition,we also consider the medium is busy at any time when the node has at least one packet in the transmission queue.2)The Transmission Queue Heuristic:The second metric isa heuristic value that is calculated with the network interface transmission queue length in the current node.Apart from the media status,the transmission queue length is also a key factor that can affect the packet latency or packet drop due to the size limit on the queue length.We deﬁne the heuristic value with the following rules.If the outgoing network interface employs a single queue scheme,the heuristic value is deﬁned as:(2) where is the length(in bytes waiting to be sent)of the interface queue in node,and is the maximum packet bytes allowed in the queue.If the network interface employs the multiple virtual queue scheme for each outgoing link,the heuristic value is deﬁned as:(3)where is the length(in bytes waiting to be sent)of the virtual queue of the link in node and denotes the neighbourhood of node as a next-hop to some destination.3)The Average MAC Layer Delay:The last metric is the MAC layer delay for the link.The MAC layer delay is deﬁned as the interval from when the RTS frame is sent at node to when the data frame is received successfully at node.The average MAC delay is obtained by averaging these values over a time window as follows:(4)where is the time interval in the window,and is a coefﬁcient.This average MAC delay indicates the degree of interference.In regions where there is a lot of interference from other nodes,MAC delay is high due to the contentionof the channel.B.Data PropagationWhen multiple virtual queue scheme is employed,the rout-ing probability value is computed by the composition ofthe pheromone values,the local heuristic values and the linkdelays as follows:(5) where,and()are tunable parametersthat control the relative weight of pheromone trail,MAC delay and heuristic value,and is the neighbourhood as a next-hop to some destination.Incorporating the heuristic value and link delay in the rout-ing computation makes this algorithm possess the congestionawareness property.Based on the probabilistic routing table, data trafﬁc will be distributed according to the probabilitiesfor each neighbour in the routing table.The routing algorithmexhibits load balancing behaviour.Nodes with a large number of packets in the buffer are avoided.The EARA-QoS algorithm consists of several components.They are the route discovery procedure,the positive and neg-ative reinforcement,and the local connectivity management.C.Route DiscoveryWe use a similar route discovery procedure as describedin[12].On initialisation,a neighbourhood for each node is built using the single-hop HELLO messages.Whenever atrafﬁc source needs a route to a destination,it broadcastsroute request packets(RQ)across the network.Rather than simplyﬂooding the RQ packets,we adopt the probabilisticbroadcast scheme explored in[30]combined with the MAClayer utilisation.When a nodeﬁrst receives a packet,with probability it broadcasts the packet to its neighbours,andwith probability it discards the packet.The probabilityvalue is calculated as(6) where()is the coefﬁcient.This broadcast scheme helps to discover new routes avoiding congestion areas,but atthe cost of missing potential routes to the destination. During the course ofﬂooding RQ packets to the destination ,the intermediate node receiving a RQ packetﬁrst sets up reverse paths to the source by recording the source addressand the previous hop node in the message cache.If a validroute to the destination is available,that is,there is at least one link associated with the pheromone trail greater than the lower pheromone bound,the intermediate node generates a route reply(RP).The RP is routed back to the source via the reverse paths.Otherwise,the RQ is rebroadcast.Other than just establishing a single forward path,whenthe destination node receives RQs it will send a RP to allthe neighbours from which it sees a RQ.In order to maintain multiple loop-free paths at each intermediate node,node(b) Path Reinforcement(c) Local Repair(a) Initial Pheromone Setup Fig.2.Illustrating Working Mechanism of EARA-QoSmust record all new forward paths that possess the latest sequence number but hold a lower hop-count in its routing table,and also send a RP to all the neighbours from which it saw a RQ.During the course of the RP tracking back to the source,an initial pheromone value is assigned to the corresponding neighbour node,which indicates a valid route to the destination.This process is illustrated in Figure2(a).D.Route ReinforcementAfter the destination node receives the data trafﬁc sent by the source node,it begins to reinforce some good neighbour(s)in order to“pull”more data trafﬁc through the good path(s)by sending reinforcement signal packets(RS) whenever it detects new good paths.When node receives a RS,it knows it has an outgoing link toward the destination ,which is currently deemed a good path.Subsequently, node updates the corresponding pheromone table entry with the value and forwards a RS packet to(at least one) selected neighbour locally based on its message cache,e.g.the neighbour(s)that saw the least hops of the incoming packets. The amount of the pheromone used to positively rein-force the previous hop neighbour is computed as follows.If the RS packet is sent by the destination to node,then is calculated using the upper bound pheromone value ,(7) If the RS packet is sent by an intermediate node towards node,the is calculated using the current largest pheromone value max()in node with the next hop to the destination in the pheromone table,max(8) where,and are parameters that control the relative weight of the relative source hop distance,the rel-ative packet number and the local queue heuristic. Incorporating the congestion-measuring metric into the reinforcement can lead data trafﬁc to avoid the congestion areas.The relative source hop distance is calculated as follows:(9) where is the shortest hop distance from the source to the current node through node,and is the shortest hop distance from to.This parameter is used to ensure that paths with shorter hop distance from the source node to the current node are reinforced with more pheromone.The relative packet number is calculated as follows:(10) where is the number of incoming packets from neighbour to the destination,and is the total number of incomingpackets towards the destination.This parameter is used to indicate that the data forwarding capacity of a link also affects the reinforcement.The more data arrives,the stronger reinforcement is generated for the corresponding link.On receiving the RS from a neighbour,node needs to positively increase the pheromone of the link towards node.If the sequence number in the RS is greater than the one recorded in the pheromone table,node updates its corresponding pheromone with the value of carried on the RS:(11) If the sequence number is equal to the current one,then:ifotherwise(12)If the sequence number in RS is less than the current one in the pheromone table,then this RS is just discarded.Node also has to decide to reinforce(at least)one of its neighbours by sending the RS message based on its own message cache.This process will continue until reaching the source node.As a result of this reinforcement,good quality routes emerge,which is illustrated in Figure2(b).The same procedure can apply to any intermediate node to perform local link error repair as long as it has pheromone value that is greater than the lower bound.For instance,if an intermediate node detects a link failure from one of its upstream links, it can apply the reinforcement rules to discover an alternative path as shown in Figure2(c).There is also an implicit negative reinforcement for the pheromone values.Within every time interval,if there is no data towards a neighbour node,its corresponding pheromone value decays by a factor as follows:(13)E.Local Foraging AntsIn a dynamic network like MANET,the changes of the net-work topology create chances for new good paths to emerge.In order to make use of this phenomenon,this algorithm launcheslocal foraging ants(LFA)with a time interval to locallysearch for new routes whenever all the pheromone trails of a node towards some destination drop below the threshold.The LFA will take a random walk from its original node. During the course of its walk,if the LFA detects congestionaround a node(the average channel utilisation is greaterthan a predeﬁned threshold value),then the LFA dies to avoid increasingly use the wireless medium.Otherwise,theLFA pushes the address of the nodes that it has travelledinto its memory stack.To avoid forming of loops,LFA will not choose to travel to the node that is already in.Before reaching the maximum hop,if LFA canﬁnd a node with pheromone trails greater than and the hop distanceto destination not greater than the one from its original nest,itreturns to its’nest’following its memory stack and updates the corresponding paths with.Otherwise,it simply dies.F.Local Connectivity ManagementNodes maintain their local connectivity in two ways.When-ever a node receives a packet from a neighbour,it updates its local connectivity information to ensure that it includes thisneighbour.In the event that a node has not sent any packets toits neighbours within a time interval,it has to broadcast a HELLO packet to its neighbours.Failure to receive packetsfrom the neighbourhood in indicates changes in the local connectivity.If HELLO packets are not received from the nexthop along an active path,the node that uses that next hop issent notiﬁcation of link failure.In case of a route failure occurring at node,cannot for-ward a data packet to the next hop for the intended destination .Node sends a RS message that sets ROUTE RERR tag to inform upstream nodes of the link failure.This RS signalassigns to the corresponding links the lower bound.Here, RS plays the role of an explicit negative feedback signal to negatively reinforce the upstream nodes along the failure path. This negative feedback avoids causing buffer overﬂow due to caching on-ﬂight packets from upstream nodes. Moreover,the use of HELLO packets can also help to ensure that only nodes with bidirectional connectivity are deemed as neighbours.For this purpose,the HELLO packet sent by a node has an option to list the nodes from which it has heard HELLO packets,and nodes that receive the HELLO check to ensure that it uses only routes to neighbours that have sent HELLO packets.G.The QoS Provision SchemeThis section describes a lightweight approach to DiffServ. The basic idea is to classifyﬂows into a predeﬁned set of service classes by their relative delay bounds.Admission control only works at the source node.There is no session orﬂow state information maintained at intermediate nodes. Once a realtime session is admitted,its packets are marked as RT(realtime service)and otherwise they are considered as best-effort bulk packets.As depicted in Figure3,each of these trafﬁc classes is buffered in a logically separate queue.A simple novel queuing strategy,based on the token bucket scheme,provides high priority to realtime trafﬁc,and also protects the lower-priority trafﬁc from starvation.No absolute bandwidth guarantees are provided in this scheme.We explain this queuing strategy and its novelty below.The queues are scheduled according to a token bucket scheme.In this scheme,prioritisation is achieved with token balancing.Each trafﬁc class has a balance of tokens,and the class with higher balance has a higher priority when dequeuing the next packet for transmission.For each transmission of a packet of class,an amount of tokens is subtracted from the class’token balance and an equal fraction thereof is added to every other class’balance such that the sum of all tokens is always the same.The weight value reﬂects the delay sensitivity assigned to the different classes.A higher weight value corresponds to a lower delay sensitivity.The size of the token balance together with the value determines the maximal length of a burst of trafﬁc from one class.In this scheme,as long as the amount of delay-sensitive trafﬁc does not grow too large,it is forwarded as quickly as possible,and if it does grow too large,starvation of other trafﬁc classes is prevented.Setting the upper bound of a class’token balance depending on its delay-sensitivity enables further tuning of the describedmethod.Fig.3.Overview of Service Differentiation SchemeIn this packet scheduling scheme,routing protocol pack-ets are given unconditional priority before other packets. Moreover,realtime applications normally have stringent delay bounds for their trafﬁc.This means that packets arriving too late are useless.From the application’s point of view,there is no difference between late and lost packets.This implies that it is actually useless to forward realtime packets that stay in a router for more than a threshold amount of time,because they will be discarded at the destination anyway.Dropping those packets instead has the advantage of reducing the load in the network.To our knowledge,this service classiﬁcation based queuing scheme is the simplest implemented QoS provisioning technique designed exclusively for MANETs so far.V.C HARACTERISTICS OF THE A LGORITHMThis proposed protocol,implementing the cross-layer design concept,exhibits some properties that show itsﬁtness as a solution for mobile ad hoc networks:Loop-freeness:during the route discovery phase,the nodes record the unique sequence number of RP packets.。

全新版大学英语(第二版)B2U2-A

Personal Income Tax in the US
individual
a progressive tax on the taxable income from the federal government of the US
personal income taxes from some state and municipal governments
be confronted with: 面临 The prisoner was confronted with his accusers.
It was early December 2003, my first season as a Salvation Army bell ringer, when I was confronted with the question.
It is a Christian charity and social services organization founded by William Booth and his wife Catherine Booth in London in 1865, which later expanded around the world. Originally known as “The Christian Mission”, the organization was renamed “Salvation Army” in 1878 thanks to a popular saying that “The Christian Mission is a volunteer army.” Nearly 33 million Americans receive assistance from The Salvation Army each year. People can help by donating money, used cars, airline mileages, used clothes and furniture for sale at Salvation Army’s thrift stores, and time.

IN4733A中文资料

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UV三点校正法测定维生素A的含量

第一法校正公式：A328(校正)=3.52(2A328-A316-A大吸收波长为327.7nm（326~329nm）各个差值均不超过±0.02，不需用校正公式。故直接用 A328进行计算。（328）= A328 /（100×ms/D） =0.746/(100×0.0048/100)=155.42 效价= ×1900=155.42×1900=295298 标示量%=[(A×D×1900×W)/(W×100×L×标示量)] ×100%=(0.746×100×1900×0.08714)/(0.0048× 100×1×25000) ×100%=102.9%
UV三点校正法测定维生素A的含量
王宇
石慧
维生素A的结构为具有一个共轭多烯醇侧链的环己烷，由于其中有多个不饱和键，性质不稳定，易被空气中氧或氧化剂氧化，易被紫外光裂解，并且其对酸不稳定。其醋酸酯比维生素A稳定，临床使用一般将本品或棕榈酸酯溶于植物油中应用。因此，维生素A及其制剂除需密封在凉暗处保存外，还需充氮或加入合适的抗氧剂。维生素A与氯仿、乙醚、环己烷或石油醚能任意混合，在乙醇中微溶，在水中不溶
B 高效液相色谱法采用RP-HPLC法同时测定人血清中维生素 A和维生素E的含量。
维生素A的含量用生物效价即国际单位（IU/g）来表示。维生素A的国际单位规定如下：1IU=0.344ug维生素A醋酸酯； 1IU=0.300ug维生素A醇。每1g维生素A醋酸酯相当的国际单位数为： 1×106/(0.344ug/IU)=2907000IU 每1g维生素A醇相当的国际单位数为： 1×106/(0.300ug/IU)=3330000IU
二法：
方法：精密称取一定量供试品，加氢氧化钾乙醇溶液后煮沸回流，得到的皂化液再经乙醚提取、洗涤、滤过、浓缩和干燥等处理，最后用异丙醇溶解残渣并稀释成每 1ml中含维生素A为9~15单位的溶液，在 300、310、325、334波长处测定吸光度，并确定最大吸收波长。计算同第一法，换算因子为1830。

A little learning is a dangerous thing

The eternal snows appear already past, And the first clouds and mountains seem the last; 不化的积雪已经越过最初的云朵和山峦似乎才刚刚经过 But, those attained, we tremble to survey The growing labors of the lengthened way; 俯瞰走过的路我们在颤抖前面的路更加不好走
The increasing prospect tires our wandering eyes, Hills over hills, and Alps on Alps arise! 前面不绝的美景迷离了我们的双眼山相连，阿尔卑斯漫无边
The introduction of the Autபைடு நூலகம்or
An Essay on Criticism是作者亚历山大〃蒲柏的第一部重要作品。在本诗中诗人将攀登艺术的高山的过程想象成攀登阿尔卑斯山的过程，诗人将在登山过程中所见所感比喻成我们在追求艺术的过程中会遇到的苦难和诱惑以及收获，以此告诫我们做任何事情都不能浅尝辄止，而应该不断努力的攀登，这样才能收获更多。具有明显的说教意义。
与此同时，这首诗歌是一首英雄偶句诗(A heroic couplet is a traditional form for English poetry, commonly used for epic and narrative poetry; it refers to poems constructed from a sequence of rhyming pairs of iambic(抑扬格的) pentameter(有五音步的) lines. )。以AABB形式押韵。

a 的韵脚

a 的韵脚
巴、芭、疤、粑、靶、捌、粑、叉、杈、差、刹、大、发、法、罚、筏、嘎、哈、虾、花、化、划、华、家、加、价、假、嫁、稼、价、咖、卡、啦、妈、麻、马、码、骂、吗、那、拿、趴、爬、怕、琶、葩、沙、纱、鲨、傻、啥、他、她、它、踏、塔、挖、娃、瓦、袜、蛙、霞、下、夏、丫、呀、压、芽、鸭、崖、涯、雅、哑、鸦、砸、眨、炸、榨、扎、渣、楂、查、咤、喳、叉、茶、搽、擦、刹、打、达、答、搭、瘩、沓、乏、伐、阀、筏、罚、嘎、蛤、哈、花、划、化、华、哗、骅、夹、荚、颊、铗、戛、佳、迦、珈、家、加、嘉、假、稼、价、驾、架、嫁、枷、夹、戛、咖、卡、夸、垮、挎、跨、啦、拉、辣、蜡、腊、麻、玛、码、蚂、马、骂、嘛、吗、拿、哪、娜、纳、捺、趴、啪、葩、帕、爬、耙、琶、傻、刹、沙、纱、鲨、砂、杀、啥、煞、厦、舍、设、射、涉、社、赦、麝、奢、赊、蛇、舌、舍、佘、它、她、踏、塌、榻、挞、榻、拓、沓、拖、托、脱、陀、驮、驼、妥、唾、哇、娃、蛙、挖、袜、洼、娲、辖、瞎、虾、匣、霞、狭、遐、辖、侠、峡、狭、下、吓、夏、厦、暇、遐、丫、压、呀、鸦、鸭、牙、芽、崖、涯、衙、哑、雅、亚、讶、蚜、砸、杂、咱、咂、扎、札、轧、闸、眨、栅、榨、咤、乍、炸、诈、蚱、眨、札、咤希望以上内容对你有所帮助。

如果你还有其他问题，请随时告诉我。

B3 Unit8 Reflections of a Chinese Mother in the West

3. Why do Western parents want to protect their children from criticism?
• Children are tender and not strong; • Parents should protect their children’s self-esteem and protect
Sum-up
Introduction
Western parents are baffled by Chinese parents’ success of raising kids. (Para. 1)
Chinese parents do things that seem provocative, unimaginable, even illegal, to opinionated Westerners. (Para. 2)
children against the feeling of failure.
4. What will Western and Chinese parents do if their child comes home with a B？
Western parents
Chinese parents
Yes. • Assume strength rather than fragility; • Be strict with you; • Not permit you to do …; • Physically punish you, such as…
Q2:Have you ever hated your parents when they forced you to do something you disliked but which later proved to be worthy of your efforts?

WAP歌词(无翻译)

I said certified freak, seven days a weekWet-ass pussy, make that pullout game weak, woo (Ah)Yeah, yeah, yeah, yeahYeah, you fuckin' with some wet-ass pussyBring a bucket and a mop for this wet-ass pussyGive me everything you got for this wet-ass pussyBeat it up, nigga, catch a chargeExtra large and extra hardPut this pussy right in your faceSwipe your nose like a credit cardHop on top, I wanna rideI do a kegel while it's insideSpit in my mouth, look in my eyesThis pussy is wet, come take a diveTie me up like I'm surprisedLet's roleplay, I'll wear a disguiseI want you to park that big Mack truck right in this little garage Make it cream, make me screamOut in public, make a sceneI don't cook, I don't cleanBut let me tell you how I got this ring (Ayy, ayy)Gobble me, swallow me, drip down the side of me (Yeah)Quick, jump out 'fore you let it get inside of me (Yeah)I tell him where to put it, never tell him where I'm 'bout to be (Huh) I'll run down on him 'fore I have a nigga runnin' me (Pow, pow, pow)Talk your shit, bite your lip (Yeah)Ask for a car while you ride that dick (While you ride that dick)You really ain't never gotta fuck him for a thing (Yeah)He already made his mind up 'fore he came (Ayy, ah)Now get your boots and your coat for this wet-ass pussy (Ah, ah, ah)He bought a phone just for pictures of this wet-ass pussy (Click, click, click) Pay my tuition just to kiss me on this wet-ass pussy (Mwah, mwah, mwah) Now make it rain if you wanna see some wet-ass pussy (Yeah, yeah) Look, I need a hard hitter, need a deep strokerNeed a Henny drinker, need a weed smokerNot a garter snake, I need a king cobraWith a hook in it, hope it lean overHe got some money, then that's where I'm headedPussy A1 just like his creditHe got a beard, well, I'm tryna wet itI let him taste it, now he diabeticI don't wanna spit, I wanna gulpI wanna gag, I wanna chokeI want you to touch that lil' dangly thing that swing in the back of my throat My head game is fire, punani DasaniIt's goin' in dry and it's comin' out soggyI ride on that thing like the cops is behind me (Yeah, ah)I spit on his mic and now he tryna sign me, wooYour honor, I'm a freak bitch, handcuffs, leashesSwitch my wig, make him feel like he cheatin'Put him on his knees, give him somethin' to believe in Never lost a fight, but I'm lookin' for a beatin'In the food chain, I'm the one that eat yaIf he ate my ass, he's a bottom-feederBig D stand for big demeanorI could make ya bust before I ever meet yaIf it don't hang, then he can't bangYou can't hurt my feelings, but I like painIf he fuck me and ask "Whose is it?"When I ride the dick, I'ma spell my name, ahYeah, yeah, yeahYeah, you fuckin' with some wet-ass pussyBring a bucket and a mop for this wet-ass pussyGive me everything you got for this wet-ass pussyNow from the top, make it drop, that's some wet-ass pussy Now get a bucket and a mop, that's some wet-ass pussy I'm talkin' wap, wap, wap, that's some wet-ass pussy Macaroni in a pot, that's some wet-ass pussy, huhThere's some whores in this houseThere's some whores in this houseThere's some whores in this houseThere's some whores in this house。

a bcc式四字词语

a bcc式四字词语
天网恢恢、想入非非、白雪皑皑、大名鼎鼎、议论纷纷、生机勃勃、得意洋洋、波光粼粼、可怜巴巴、目光炯炯、气喘吁吁、言之凿凿、人才济济、热气腾腾、白发苍苍、饥肠辘辘、风尘仆仆、含情脉脉、兴致勃勃、微波粼粼、行色匆匆、野心勃勃、仪表堂堂、衣冠楚楚、精神奕奕、众目睽睽、书声琅琅、信誓旦旦、其乐融融、无所事事、心事重重、情意绵绵、逃之夭夭、杀气腾腾、两手空空、人心惶惶、小心翼翼、喜气洋洋、相貌堂堂、顾虑重重、威风凛凛、负债累累、忠心耿耿、死气沉沉、千里迢迢、荒草萋萋、来势汹汹、忧心忡忡、百鸟啾啾、大汗涔涔、绨袍恋恋、泪光涟涟、人影幢幢、神采奕奕、威风堂堂、岁月匆匆、北芒垒垒、囊橐累累、流水潺潺、前途茫茫、虎视眈眈、轻烟袅袅、细雨霏霏、兴致冲冲、衣袂翩翩、夏屋渠渠、瓜瓞绵绵、秋风习习、泪光涟涟、恩怨了了、天下汹汹、惟余莽莽、天下滔滔、书记翩翩、法网恢恢、颠毛种种、瓜瓞绵绵、文质彬彬、血迹斑斑、望眼巴巴、窈窕冥冥、余音袅袅、鸿飞冥冥、前途茫茫、虎视眈眈、螽斯诜诜、神气扬扬、文采奕奕、飞鸿冥冥、余音袅袅、惟余莽莽、鸿飞冥冥、道路纷纷、苦海茫茫、七魄悠悠、万众睢睢、微风习习、秋波澹澹、冬夏青青、傲骨嶙嶙、剑戟森森、谗口嚣嚣、星光熠熠、名声赫赫、流水汩汩、血泪斑斑、意气扬扬、朝气勃勃、荒草凄凄、绿水滔滔、春意浓浓、听之藐藐、言笑晏晏、琴声瑟瑟、血迹斑斑、天心恋恋、边老便便、风尘碌碌、言笑晏晏、小时了了、帽儿光光、枵肠辘辘、画里真真、十指尖尖、福乐绵绵、草色青青、人言啧啧、波光鳞鳞、钉头磷磷、輷鞫殷殷、我是优优、小宝哈哈、软古囊囊、暖风徐徐、余生袅袅、溪水淙淙、旌旗猎猎、谠论侃侃、一貌堂堂、烟雾袅袅、利口喋喋、流水淙淙、晚风徐徐。