英文文献翻译
英文文献整篇翻译
英文文献整篇翻译Title: The Impact of Climate Change on BiodiversityClimate change is a pressing issue that has significant impacts on biodiversity worldwide. Changes in temperature, precipitation patterns, and extreme weather events are altering ecosystems and threatening the survival of many species. The loss of biodiversity not only affects the natural world but also has implications for human societies.One of the major impacts of climate change onbiodiversity is the shifting of habitats. As temperatures rise, many species are forced to move to higher latitudesor elevations in search of suitable conditions. This can disrupt ecosystems and lead to the decline or extinction of species that are unable to adapt to the new conditions.In addition to habitat loss, climate change is also causing changes in the timing of biological events such as flowering, migration, and reproduction. These changes can disrupt the delicate balance of ecosystems and lead to mismatches between species that depend on each other for survival.Furthermore, climate change is exacerbating otherthreats to biodiversity such as habitat destruction, pollution, and overexploitation. The combination of these factors is putting immense pressure on many species and pushing them closer to extinction.It is essential that we take action to mitigate the impacts of climate change on biodiversity. This includes reducing greenhouse gas emissions, protecting and restoring habitats, and implementing conservation measures to safeguard vulnerable species. By addressing the root causes of climate change and protecting biodiversity, we canensure a sustainable future for both the natural world and human societies.气候变化对生物多样性的影响气候变化是一个紧迫的问题，对全球的生物多样性产生重大影响。
英文文献pdf翻译成中文
英文文献pdf翻译成中文
对于将英文文献PDF翻译成中文，有几种常见的方法可以实现。
首先，你可以使用在线翻译工具，如Google翻译或百度翻译，直接
上传PDF文件并选择需要翻译的语言。
这些工具可以快速将整个文
档翻译成中文，但需要注意的是，由于自动翻译的限制，可能会出
现一些翻译不准确或不通顺的情况，特别是对于专业术语或复杂句子。
其次，你也可以雇佣专业的翻译人员或翻译公司来完成这项任务。
他们可以提供更准确、流畅的翻译，尤其是对于专业领域的文献，这种方式会更可靠。
然而，这需要一定的成本和时间，因为翻
译人员需要逐字逐句地进行翻译，并且可能需要进行专业术语的翻
译和校对。
另外，如果你自己对英文和中文都比较熟悉，也可以考虑自行
翻译。
这种方式可以确保翻译的准确性和流畅性，但需要花费较多
的时间和精力。
无论采用哪种方式，翻译文献需要保证准确性和完整性，尤其
是对于学术文献或专业领域的文献。
希望这些信息能够帮助你找到合适的方法来将英文文献PDF翻译成中文。
英文文献用翻译
Adult【成年人】Aged【老年人】Aged, 80 and over【老年人, 80以上】Catheterization, Central Venous/*instrumentation/methods【*导管插入术, 中心静脉/*仪器/方法】Cost-Benefit Analysis【费用效益分析】Equipment Design【设备设计】Equipment Failure【设备失效】Equipment Safety【设备安全性】Female【女(雌)性】Humans【人类】Infusion Pumps, Implantable/adverse effects/*economics【*输注泵, 植入型/副作用/*经济学】Male【男(雄)性】Middle Aged【中年人】Neoplasms/*drug therapy/pathology【*肿瘤/*药物疗法/病理学】Probability【概率】Prospective Studies【前瞻性研究】Risk Assessment【危险性评估】Sensitivity and Specificity【敏感性与特异性】Treatment Outcome【治疗结果】Vascular Patency【血管未闭】Venous Thrombosis/prevention & control【静脉血栓形成】Adolescent【青少年】Adult【成年人】Aged【老年人】Aged, 80 andover【老年人, 80以上】AntineoplasticAgents/*administration& dosage【*抗肿瘤药】*Catheters,Indwelling/adverseeffects/economics【*导管, 留置/副作用/经济学】Female【女(雌)性】Humans【人类】*Infusion Pumps,Implantable/adverse。
英文文献全文翻译
英文文献全文翻译全文共四篇示例，供读者参考第一篇示例：LeGuin, Ursula K. (December 18, 2002). "Dancing at the Edge of the World: Thoughts on Words, Women, Places".《世界边缘的舞蹈：关于语言、女性和地方的思考》Introduction:In "Dancing at the Edge of the World," Ursula K. LeGuin explores the intersection of language, women, and places. She writes about the power of words, the role of women in society, and the importance of our connection to the places we inhabit. Through a series of essays, LeGuin invites readers to think critically about these topics and consider how they shape our understanding of the world.Chapter 1: LanguageConclusion:第二篇示例：IntroductionEnglish literature translation is an important field in the study of language and culture. The translation of English literature involves not only the linguistic translation of words or sentences but also the transfer of cultural meaning and emotional resonance. This article will discuss the challenges and techniques of translating English literature, as well as the importance of preserving the original author's voice and style in the translated text.Challenges in translating English literature第三篇示例：Title: The Importance of Translation of Full English TextsTranslation plays a crucial role in bringing different languages and cultures together. More specifically, translating full English texts into different languages allows for access to valuable information and insights that may otherwise be inaccessible to those who do not speak English. In this article, we will explore the importance of translating full English texts and the benefits it brings.第四篇示例：Abstract: This article discusses the importance of translating English literature and the challenges translators face when putting together a full-text translation. It highlights the skills and knowledge needed to accurately convey the meaning and tone of the original text while preserving its cultural and literary nuances. Through a detailed analysis of the translation process, this article emphasizes the crucial role translators play in bridging the gap between languages and making English literature accessible to a global audience.IntroductionEnglish literature is a rich and diverse field encompassing a wide range of genres, styles, and themes. From classic works by Shakespeare and Dickens to contemporary novels by authors like J.K. Rowling and Philip Pullman, English literature offers something for everyone. However, for non-English speakers, accessing and understanding these works can be a challenge. This is where translation comes in.Translation is the process of rendering a text from one language into another, while striving to preserve the original meaning, tone, and style of the original work. Translating afull-length English text requires a deep understanding of both languages, as well as a keen awareness of the cultural andhistorical context in which the work was written. Additionally, translators must possess strong writing skills in order to convey the beauty and complexity of the original text in a new language.Challenges of Full-text TranslationTranslating a full-length English text poses several challenges for translators. One of the most significant challenges is capturing the nuances and subtleties of the original work. English literature is known for its rich and layered language, with intricate wordplay, metaphors, and symbolism that can be difficult to convey in another language. Translators must carefully consider each word and phrase in order to accurately convey the author's intended meaning.Another challenge of full-text translation is maintaining the author's unique voice and style. Each writer has a distinct way of expressing themselves, and a good translator must be able to replicate this voice in the translated text. This requires a deep understanding of the author's writing style, as well as the ability to adapt it to the conventions of the target language.Additionally, translators must be mindful of the cultural and historical context of the original work. English literature is deeply rooted in the history and traditions of the English-speaking world, and translators must be aware of these influences in orderto accurately convey the author's intended message. This requires thorough research and a nuanced understanding of the social, political, and economic factors that shaped the work.Skills and Knowledge RequiredTo successfully translate a full-length English text, translators must possess a wide range of skills and knowledge. First and foremost, translators must be fluent in both the source language (English) and the target language. This includes a strong grasp of grammar, syntax, and vocabulary in both languages, as well as an understanding of the cultural and historical context of the works being translated.Translators must also have a keen eye for detail and a meticulous approach to their work. Every word, sentence, and paragraph must be carefully considered and translated with precision in order to accurately convey the meaning of the original text. This requires strong analytical skills and a deep understanding of the nuances and complexities of language.Furthermore, translators must possess strong writing skills in order to craft a compelling and engaging translation. Translating a full-length English text is not simply a matter of substituting one word for another; it requires creativity, imagination, and a deep appreciation for the beauty of language. Translators mustbe able to capture the rhythm, cadence, and tone of the original work in their translation, while also adapting it to the conventions of the target language.ConclusionIn conclusion, translating a full-length English text is a complex and challenging task that requires a high level of skill, knowledge, and creativity. Translators must possess a deep understanding of both the source and target languages, as well as the cultural and historical context of the work being translated. Through their careful and meticulous work, translators play a crucial role in making English literature accessible to a global audience, bridging the gap between languages and cultures. By preserving the beauty and complexity of the original text in their translations, translators enrich our understanding of literature and bring the works of English authors to readers around the world.。
pdf英文文献翻译
pdf英文文献翻译 PDF English Literature Translation With the advances in technology, the use of electronic documents has become increasingly popular. PDF, short for Portable Document Format, is one of the most widely used file formats for sharing and distributing electronic documents. For researchers and academicians, access to Englishliterature is critical as it contributes to the expansion of knowledge and encourages global collaboration. However, not all scholars are proficient in English, which creates a need for the translation of English literature, especially in the form of PDFs. In this document, we will explore the importance and challenges of translating English literature into PDF format, along with some best practices for effective translation. 1. Importance of PDF English Literature Translation Translation of English literature into PDF format enables scholars from non-English speaking backgrounds to access and understand research findings from across the globe. It promotes inclusivity and fosters collaboration among academics, thereby facilitating the advancement of knowledge in various fields. Additionally, translated PDF literature helps in disseminating research in conferences and seminars, extending the reach and impact of the work. 2. Challenges in PDF English Literature Translation Translating English literature into PDF format presents several challenges. Firstly, the accuracy of the translation is paramount to ensure the intended meaning is not lost. Translators must possess a strong command of boththe source and target languages to accurately capture the nuances and essence of the text. Additionally, the formatting and layout of the PDF document must be preserved during the translation process. Maintaining the structure ensures that the translated document remains visually appealing and user-friendly. 3. Best Practices for Effective PDF English Literature Translation To ensure successful translation of English literature into PDF format, adhering to these best practices is imperative: a. Engage professional translators with subject matter expertise: It is crucial to collaborate with professional translators who possess knowledge in the specific field of the English literature being translated. Their expertise ensures accurate rendering of technical terms and concepts. b. Use industry-standard translation tools: Employing computer-assisted translation (CAT) tools like SDL Trados or MemoQ enhances efficiency and consistency. These tools support translation memory, maintaining consistency across the translated documents. They also allow for easy management of terminology glossaries. c. Preserve the formatting and layout: Implementing a robust translation workflow that includes preserving the formatting and layout of the PDF document is essential. This can be achieved by using specialized software that preserves the structure and visual appeal of the original document. d. Proofread and edit thoroughly: After the initial translation, it is crucial to invest time in thorough proofreading and editing. This ensures the accuracy and quality of the translated PDF document. A fresh pair of eyes can detect any errors or inconsistencies that might have been overlooked during the translation process. e. Obtain feedback from target audience: Feedback from the target audience can provide valuable insights into the effectiveness of the translated PDF document. This feedback can help improve future translations and ensure theaudience's needs are met. In conclusion, the translation of English literature into PDF format plays a crucial role in enabling worldwide collaboration and knowledge exchange. By recognizing the importance of accuracy, formatting preservation, andutilizing professional translators and industry-standard tools, the effective translation of English literature can be achieved. Adopting best practices ensures that the translated PDF documents are of high quality, visually appealing, and accessible to scholars from non-English speaking backgrounds.。
英文文献原文及对应翻译
Adsorption char acter istics of copper , lead, zinc and cadmium ions by tourmaline(环境科学学报英文版) 电气石对铜、铅、锌、镉离子的吸附特性JIANG Kan1,*, SUN Tie-heng1,2 , SUN Li-na2, LI Hai-bo2(1. School of Municipal and Environmental Engineering, Harbin Institute of Technology, Harbin 150090, China. jiangkan522@; 2. Key Laboratory of Environmental Engineering of Shenyang University, Shenyang 110041, China)摘要：本文研究了电气石对Cu2+、Pb2+、Zn2+和Cd2+的吸附特性，建立了吸附平衡方程。
研究四种金属离子的吸附等温线以及朗缪尔方程。
结果表明电气石能有效地去除水溶液中的重金属且具有选择性：Pb2+> Cu2+> Cd2+> Zn2+。
电气石对金属离子吸附量随着介质中金属离子的初始浓度的增加而增加。
电气石也可以增加金属溶液的pH值；发现电气石对Cu2+、Pb2+、Zn2+和Cd2+的最大吸附量为78.86、154.08、67.25和66.67mg/g；温度在25-55℃对电气石的吸附量影响很小。
此外研究了Cu2+、Pb2+、Zn2+和Cd2+的竞争吸附。
同时观察到电气石对单一金属离子的吸附能力为Pb>Cu>Zn>Cd，在两种金属系统中抑制支配地位是Pb>Cu，Pb>Zn，Pb>Cd，Cu>Zn，Cu>Cd，和Cd>Zn。
关键字：吸附；重金属含量；朗缪尔等温线；电气石介绍重金属是来自不同行业排出的废水，如电镀，金属表面处理，纺织，蓄电池，矿山，陶瓷，玻璃。
英文文献及翻译
Geotextile reinforced by soft soil1. IntroductionGeotextile known, it has high tensile strength, durability, corrosion resistance, texture, flexibility, combined with good sand, to form reinforced composite foundation, effectively increase the shear strength , tensile properties, and enhance the integrity and continuity of soil. Strengthening mechanism for the early 60's in the 20th century, Henri Vidal on the use of triaxial tests found a small amount of fiber in the sand, the soil shear strength can improve the image of more than 4 times in recent years, China's rock Laboratory workers also proved in the reinforced sand can effectively improve the soil's bearing capacity, reduce the vertical ground settlement, effectively overcome the poor soil and continuity of overall poor performance. As with the above properties of reinforced soil and the characteristics of its low price, so the project has broad application prospects.2.1 Project OverviewThe proposed retaining wall using rubble retaining wall of gravity, the wall is 6 meters high, the bearing capacity of foundation soil required to 250kPa, while the basement geology from the top down as follows: ①clay to a thickness of 0.7 to 2 meters saturated, soft plastic; ② muddy soil, about 22 - 24 meters thick, saturated, mainly plastic flow, local soft plastic; ③ sand layer to a thickness of 5 to 10 meters, containing silty soil and organic matter, saturated, slightly wet; ④ gravel layer, the thickness of the uneven distribution points, about 0 to 2.2 meters, slightly dense; ⑤ weathered sandstone. Including clay and silty soil bearing capacity is 70kPa, obviously do foundation reinforcement.2.2 Enhanced Treatment of reinforced foundation cushion Reinforcement replacement method can be used for sand and gravel used forsoil treatment, but due to loose bedding, based on past experience, witha gravel mat to treat a large settlement of the foundation always exist, even the characteristics of poor, often resulting in cracks in the superstructure, differential settlement of the image, this works for6-meter-high rubble retaining walls, height and large, and because the walls are 3 meters high wall, if there is differential settlement of retaining walls, cracks, will result in more serious consequences and thus should be used on the cushion reinforcement through economic and technical analysis, decide on the sand and gravel stratum were reinforced hardening. Reinforcement treatment method: first the design elevation and the basement excavation to 200mm thick layer of gravel bedding, and then capped with a layer of geotextile, and then in the thick sand and gravel on the 200, after leveling with the yellow sand using roller compaction; second with loaded bags of sand and gravel laying of geotextile, the gap filled with slag, geotextile bags capped 100 thick gravel, roller compaction. Its on repeat laying geotextile → → compacted gravel, until the design thickness of the cushion, the bridge is 1 m thick cushion, a total of 4 layers of geotextile, two bags of sand.This method works fast, simple machine, investment, after years of use, that reinforce good effect, building and construction units are satisfied.3 ExperienceTo achieve the reinforced soil reinforcement effect, must be reinforced earth construction technology, construction strict quality control: 1, geotextile should increase the initial pre-stress, and its end should be a reliable anchor to play the tensile strength of geotextile, anchoring more firmly, more capacity to improve, the foundation of the stress distribution more uniform, geotextile side Ministry of fixed length by laying end to ensure the fold, the folded end wrapped sand to increase its bond strength to ensure that the use will not be pulled out duringthe period.Second, the construction process have a significant effect on the reinforcement effect, the construction should be as soon as possible so that geotextile in tension, tensile strength geotextile can be played only when the deformation, so do not allow construction of geotextile crease occurs, the earth Fabric tension leveling as much as possible. Geotextile in order to have enough by the early Dutch strain, according to the following procedure works: ① laying geotextile; ② leveled the tension at both ends; both ends of the folded package gravel and sand filling at both ends; ③ center fill sand; ④ 2 higher end of sand; ⑤ Finally, the center of sand filling. Click here to enable the construction method of forming corrugated geotextile being stretched as soon as possible, to play a role in the early loaded.Third, the construction of geotextile-reinforced cushion should the level of shop using geotextile geotextile and laying of gravel bags cushion the turn to play bag cushion integrated turn out good, flexural rigidity, and dispersion of good and peace bedding layer of the overall continuity of good advantages.4 ConclusionGeotextile reinforced by soft soil is an effective, economical, safe, reliable, simple method, but the literature describes only qualitative, experience more components, yet the lack of rigorous The theoretical formula, reliable test data to be adequate, these are yet to be theoretical workers and the general engineering and technical personnel continue to explore.土工织物加筋垫层加固软土地基1. 引言土工织物又称土工聚合物，它具有高抗拉强度，耐久性、耐腐蚀性，质地柔韧，能与砂土很好地结合，组合成加筋土复合地基，有效地提高土的抗剪强度、抗拉性能，增强土体的整体性和连续性。
八大英文文献翻译神器
你值得拥有的八大英文文献翻译神器不管是做科研还是写SCI论文，开始都需要阅读大量的文献，做课题至少查阅600篇，粗看300篇，细看100篇，研读50篇，在看到一叠叠论文后，由于语言问题，往往会觉得无从下手，下面分享几款常用的文献翻译神器。
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5、CNKI翻译CNKI翻译助手是一款专业的学术翻译工具，由“中国知网”开发制作，汇集了从CNKI系列数据库中挖掘的大量常用词汇、专业术语、成语俚语及双语例句等，形成海量中英在线词典和双语平行语料库。
6、LingoesLingoes是一款简明易用的词典与文本翻译软件，支持全球超过80多种语言的词典查询、全文翻译、屏幕取词、划词翻译、例句搜索、网络释义和真人语音朗读功能。
7、有道词典有道词典是个神器，尤其是查词、划词、取词的方面特别突出，词库中有所有专业用语的补充包，可以让你瞬间翻译出各种专业的英文单词，从复杂的有机化合物，到稀奇古怪的动物名，哪里不会点哪里。
8、Copy Translator比较适用于即时翻译，内置了谷歌翻译、百度翻译、有道翻译、搜狗翻译、彩云翻译和腾讯翻译几种不同的翻译引擎，随意切换，总有一个适合你。
英文文献翻译
Political Stability and Foreign Direct InvestmentKim Haksoon1．INTRODUCTIONF oreign direct investment (FDI) has become the important issue in finance and economics since the globalization of capital markets. The saturation of domestic capital market drives each country to invest in the foreign capital markets in terms of financial internationalization. Recently, emerging market countries, especially China and India, become the world's foremost FDI targets. From the World Bank (2002) report, we can see that net FDI to developing countries has increased since 1985.Many researchers in finance and economics try to find the factors that affect the FDI. For example, Lucas (1990) argues that only political risk is an important factor in limiting capital flows. Investments in many developing countries are exposed to large political risks, so FDI inflows are large for politically unstable countries. By the same token, FDI outflows are large for politically stable countries to invest in countries with large political risks. Fry, Classens, Burridge, & Blanchet (1995) found that the requirement to surrender export proceeds to the monetary authorities and the existence of special exchange rates for some capital account transactions reduces the probability that FDI is independent. The more liberal a country's foreign exchange system, the more likely FDI is to be independent or exogenous. FDI is associated with a larger increase in capital formation when it is independent than when it is "Granger-caused" by other capital flows. Singh and Jun (1995) also show that political risk and business operating conditions have been important determinants of FDI for countries that have historically attracted high FDI. For countries with relatively low FDI, a key determinant was the degree of sociopolitical instability. A country's orientation toward exports is the strongest variable for explaining why a country attracts FDI. Chan and Gemayel (2004) find that the degree of instability associated with investment risk is a much more critical determinant of foreign investment in the Middle East and North Africa region countries than it is for developing countries, which have lower level investment risk.There are other factors, including above-mentioned ones of FDI. They are macroeconomic determinants、internalization theory、intangible assets、capital market mispricing、shareholder's wealth effect and stock market liberalization and corporategovernance.In view of related literature, we can see that there are numerous factors that affect FDI, but not dominant factors. The objective of this paper comes from the Lucas (1990)'s argument that only political risk is an important factor in limiting capital flows. According to his paper, either human capital based approach or monopoly rents approach is not an important factor in explaining capital flows. For the empirical support and extension of his argument, we examine the following hypothesis.a. Hypothesis 1FDI inflows are high for politically unstable countries, while FDI outflows are high for politically stable countries, after controlling for macroeconomic factors.La Porta et al. (1999) constructs the quality of government index around the world. They divide government quality variables by five categories, and find that rich nations have better governments than poor ones. Ethnolinguistically homogenous countries have better governments than the heterogeneous ones. Common law countries have better governments than French civil law or socialist law countries. Predominantly Protestant countries have better governments than either predominantly Catholic or predominantly Muslim countries. The quality of governments also is closely related to its interference with private sectors. However, they did not mention whether the political stability of governments goes hand in hand with its interference with private sectors. From their five categories, we use the direct measure of political stability. They are corruption index in the government efficiency category and political rights index and democratic index from political freedom category. Corruption index is the index of corruption in government from International Country Risk Guide (ICRG). Low corruption index means high political stability. Political rights index is the index of political rights from Freedom of the World, 1996. Democracy index is the average of democracy score for the period 1970-1994 from Polity III: Regime Type and Political Authority, 1800-1994. High political rights index and democracy index mean high political stability.We know that the quality of government is closely related to its interference with private sectors, leading to the performance of private sectors. However, we do not know whether the political stability of government is related to its interference with private sectors. We argue that political stability measures are closely related to the performance of the private sector in general, and it will also affect the FDI inwardperformance, by looking at the recent economic development of China and Russia. (Note 2) Their line of reasoning is also consistent with the view of Lucas (1990), because politically unstable countries attract more capital flows which lead to the higher possibility of better performance of FDI. By combining the argument of Lucas (1990) and La Porta et al. (1999), we can construct a following hypothesis.b. Hypothesis 2FDI inward performance is high for politically unstable countries, after controlling for macroeconomic factors.The remaining paper proceeds as follow. Section 2 describes the econometric techniques and the model setup that are used in this paper. Section 3 explains data and variable construction. Section 4 shows empirical results Section 5 ends the paper.2. THE REVIEW OF ECONOMETRIC TECHNIQUES AND MODEL SRTUPSince our sample is the panel data, we perform three different empirical techniques for the panel data to strengthen our empirical results. First, we perform pooled ordinary least squares (OLS) with robust standard errors for the panel data using robust (cluster) covariance matrix as in Wooldridge (2002). According to Wooldridge (2002), the error term in the panel data will be serially correlated, even if the pooled OLS meets the consistency assumption. Also, the serial correlation does not decrease as the cross-section and time-series increases. So, we need to use robust (cluster) covariance matrix.Second, we perform feasible generalized least squares (GLS) for the cross-sectional time-series linear models. This technique allows estimation in the presence of AR(1) autocorrelation within panels and cross-sectional correlation and heteroskedasticity across panels.3. DATA AND VARIABLE DESCRIPTIONDifferent data sources are used in this paper. FDI data is from World Investment Report (WIR) Annex Tables, the United Nations Conference on Trade and Development (UNCTAD). World Investment Report Annex Tables provide detailed statistical data on FDI flows, FDI stock and cross-border mergers and acquisitions. We use three year average FDI inflows, FDI outflows and the performance of FDI inflows as dependent variables in the regression analysis. We matched the latest year of the three year to the year of controlling variables. (Note 4) The three year average of FDI inflows is the three year average foreign direct investment inflows in millions of dollars. The three year average of FDI outflows is the three year average foreigndirect investment outflows in millions of dollars. The three year average performance of FDI inflows is the three year average inward foreign direct investment performance index. If the performance is better, the index shows greater value. These variables are all from World Investment Report (WIR) Annex Tables, the United Nations Conference on Trade and Development (UNCTAD).Controlling variables are as follow. GDP is the three year average GDP in millions of dollars. Three of them come from World Investment Report (WIR) Annex Tables, the United Nations Conference on Trade and Development (UNCTAD). The real exchange rate is calculated using nominal exchange rates and price indices from the IMF International Financial Statistics. There are several papers analyzing the relationship between exchange rate and FDI (Froot and Stein, 1991; Klein and Rosengren, 1994; Dewenter, 1995; Blonigen, 1997). Corporate top tax rates, which are the maximum marginal corporate tax rates in each country and year, are from the World Tax Database maintained by the Office of Tax Policy Research at the University of Michigan. There is a paper investigating the relationship between tax rate and FDI (Desai et al., 2004). Capital account openness is based on Brune et al. (2001). We form a closedness index, using Brune et al. (2001) data, as the way in Baker et al. (2006). Political stability measures are described briefly in the introduction section.4. EMPIRICAL RESULTSa. Summary statisticsDescriptive statistics for the entire sample is presented in Table 1. The definitions of the variables are the same as the ones in Table 1. Total of 305 country year observations are in the sample from 1990 till 2002 spanning 28 countries. Some countries have missing real exchange rate data, so the exchange rate series for these countries are indexed with the dollar exchange rate in the year that is observed first. Democratic index (democratic) and public sector employment ratio (PSEmpRatio) are missing for Hong Kong. Government consumption expenditures (GC/GDP) and total government transfers and subsidies are missing for China. Public sector employment ratio is missing for Israel. The mean FDI flows are similar, while their median is significantly different from the mean. The standard deviations of FDI flows are large.For example, the standard deviation of FDI outflows is almost the twice of its mean value. It suggests that each country's FDI flows vary over its characteristics. FDI inward performance also varies over each country's characteristics. The mean FDI inward performance is close to the standard deviation, while median value is relatively close to the mean. Overall, FDI flows and inward performance significantlydepend on each country's characteristics.The political stability also varies over the country's characteristics. The mean value ranges from 6.03 to 7.94. The mean value of corrupt is close to that of democratic, while the standard deviation is higher for democratic. Also, the difference between mean and median for democratic is the highest among the political stability variables. Democratic shows the highest standard deviation, while political shows the lowest standard deviation. From the minimum and maximum values of political stability variables, we can see that political stability varies from country to country. For the variables of the size of public sector category, GC/GDP and T&S/GDP have similar mean and median values. The standard deviation is a little higher for GC/GDP than that for T&S GDP. The highest government consumption or transfers and subsidies as a percentage of GDP is around five or twenty seven times greater than the lowest government consumption or transfers and subsides as a percentage of GDP, respectively. The mean value of the average ratio of public sector employment in general government as a percentage of total population is 5.71. So, on average, the 5.71 percent of total population is hired in public sector. The mean and median value is close with each other, but the standard deviation is high relative to the mean value. The maximum value is around seventeen times higher than the minimum value. Overall, the size of public sector varies from country to country.b. Pearson CorrelationThe Pearson correlations among independent variables are presented in Table 2. All the independent variables have the possible correlation with dependent variables judging from related literature. Overall, independent variables are correlated with one another within a conventional five percent significance level, except for some pairs. For example, Ex Rate is not correlated with political with statistical significance. GDP shows negative correlations with political stability variables. Interestingly, it suggests that high GDP countries have less corruption, while their political rights and the level of democracy are low. Also, Ex Rate shows negative correlations with corrupt and democratic, indicating high real exchange rate countries have less corruption, but their democratic level is low. Corp Tax shows positive correlations with political and democratic. So, countries with high maximum marginal corporate tax rate show high political rights and level of democracy. The result is also interesting, because countries which are not open to capital flows do not necessarily have corrupted government.c. Empirical ResultsAs you can see, corrupt and political consistently affect the FDI inflows and inward performance for pooled OLS and feasible GLS estimation. Corrupt has a positive relationship with the FDI inflows and inward performance, while political has a negative relationship with the FDI inflows and inward performance for pooled OLS and feasible GLS estimation. Countries with high corruption of government and low political rights have the high FDI inflows. The results are consistent with the argument of Lucas (1990) and our hypothesis 1. Consistent with our hypothesis 2, they have the high FDI inward performance. For the random effects estimation, corrupt is positively correlated with the FDI inward performance, while political is negatively correlated with the FDI inward performance. The results are consistent with our hypothesis 2.For the control variables, only GDP has consistently positive relationship withthe FDI flows, while it is negatively correlated with the FDI inward performance. High GDP countries have more FDI flows, while its FDI inward performance is low. Consistent with the argument of Lucas (1990), the FDI outflows in high GDP countries are high, assuming high GDP countries are politically stable, in general. However, those countries also have the high FDI inflows and low FDI inward performance. It seems that, in general, high GDP countries are politically stable and the FDI inflows should come from the low GDP countries with political instability. If Lucas (1990)'s argument is correct, the FDI inflows from countries with political instability is limited. Since this kind of FDI inflows are limited by countries with political stability, it seems that the FDI inward performance of this kind should be poor due to the limitation by the government of hosting countries. Also, the FDI inflows are high for the high GDP countries, not consistent with our hypothesis 1, assuming high GDP countries are politically stable. In general, high GDP countries have more foreign trades than low GDP countries, so the absolute volume of FDI flows should be higher for high GDP countries.5. CONCLUSIONThe determinants of FDI flows are well documented in the related literature. By using the three different techniques of panel data, we investigate the relationship between the FDI and the political stability in detail by looking at FDI flows, inward performance and the specifically categorized political stability variables as in La Porta et al. (1999).The main empirical results can be summarized as follow. First, hosting countries with higher political rights as in La Porta et al. (1999) have higher FDI outflows after controlling for macroeconomic variables. The result is consistent with Lucas (1990) and our hypothesis 1 in that politically stable countries produce capital flows to invest in politically unstable countries. Second, hosting countries with higher level of corruption of governments and lower level of democracy attract more FDI inflows after controlling for macroeconomic variables. The result is also consistent with the argument of Lucas (1990) and our hypothesis 1 that politically unstable countries attract capital flows from developed countries with high political stability. Third, consistent with our hypothesis 2, FDI inward performance is positively correlated with the corruption level of governments and negatively correlated with the level of democracy. Fourth, when the key variables of the factor analysis from La Porta et al. (1999) are included, countries with high corruption level of governments and lowerpolitical rights have higher FDI inward performance.The contribution of this paper is as follow. First, we support the related literature of Lucas (1990) that FDI flows are affected by the level of political stability of hosting countries, using the detailed political stability measures of governments, which is the approach that is not taken before. Second, our results contribute to the related literature by further looking at the relationship between FDI inward performance and the level of political stability of hosting countries with the combination of arguments of Lucas (1990) and La Porta et al. (1999). Finally, our empirical results are strengthened by taking three relevant econometric techniques of panel data: pooled OLS estimation with robust standard errors, cross-sectional time-series feasible GLS estimation and random effects estimation.政治的稳定性与外商直接投资哈克森·金1.引言随着资本市场的全球化，FDI已经成为金融和经济学界的重要议题。
英文文献翻译格式
英文文献翻译格式
英文文献翻译格式通常包括以下几个方面:
1. 文献信息：在翻译文献之前，首先要提供文献的基本信息，包括作者、标题、期刊/书名、出版日期等。
通常按照以下格式进行排列：
[作者姓氏]，[作者名字]. [文章标题]. [期刊/书名]. [出版日期].
2. 翻译译者：如果是自己翻译的文献，应该标明自己是译者。
可以在文献信息的末尾加上"Translated by: [译者姓名]"或者"Translation by: [译者姓名]"。
3. 段落翻译：在翻译文献的内容时，可以将原文按照段落进行翻译，并使用缩进或者空行进行分隔。
可以使用换行符或者段落符号表示新的段落。
4. 引用翻译：如果在翻译过程中需要引用原文的内容，可以使用引号标注，同时在引用的末尾注明原文的出处。
可以使用段落符号或者引用标记来引用内容。
5. 注释：如果在翻译过程中需要添加注释或者补充说明，可以使用括号或者脚注来表示。
注释应该直接放在被注释的内容后面，使用合适的标点符号进行分割。
6. 标题翻译：如果文献中包含标题或子标题，应该将其翻译成对应的中文。
可以将翻译后的标题用加粗、斜体、下划线等格
式进行标记，以便读者区分。
7. 插图翻译：如果文献中包含插图或者图片，通常需要对其进行翻译。
可以在插图下方或者旁边加上对应的中文说明，以方便读者理解。
总体而言，英文文献翻译格式应该清晰明了，准确无误地传达原文的信息。
要注重原文内容的准确性，并注意译文的语法、词汇、结构等方面的准确性和流畅度。
英文文献小短文(原文加汉语翻译)
A fern that hyperaccumulates arsenic(这是题目，百度一下就能找到原文好，原文还有表格，我没有翻译)A hardy, versatile, fast-growing plant helps to remove arsenic from contaminated soilsContamination of soils with arsenic,which is both toxic and carcinogenic, is widespread1. We have discovered that the fern Pteris vittata (brake fern) is extremely efficient in extracting arsenic from soils and translocating it into its above-ground biomass. This plant —which, to our knowledge, is the first known arsenic hyperaccumulator as well as the first fern found to function as a hyperaccumulator— has many attributes that recommend it for use in the remediation of arsenic-contaminated soils.We found brake fern growing on a site in Central Florida contaminated with chromated copper arsenate (Fig. 1a). We analysed the fronds of plants growing at the site for total arsenic by graphite furnace atomic absorption spectroscopy. Of 14 plant species studied, only brake fern contained large amounts of arsenic (As;3,280–4,980 We collected additional samples of the plant and soil from the contaminated site –1,603 As) and from an uncontaminated site –As). Brake fern extracted arsenic efficiently from these soils into its fronds: plantsgrowing in the contaminated site contained 1,442–7,526 Arsenic and those from the uncontaminated site contained –These values are much higher than those typical for plants growing in normal soil, which contain less than of arsenic3.As well as being tolerant of soils containing as much as 1,500 arsenic, brake fern can take up large amounts of arsenic into its fronds in a short time (Table 1). Arsenic concentration in fern fronds growing in soil spiked with 1,500 Arsenic increased from to 15,861 in two weeks. Furthermore, in the same period, ferns growing in soil containing just 6 arsenic accumulated 755 Of arsenic in their fronds, a 126-fold enrichment. Arsenic concentrations in brake fernroots were less than 303 whereas those in the fronds reached 7,234 of 100 Arsenic significantly stimulated fern growth, resulting in a 40% increase in biomass compared with the control (data not shown).After 20 weeks of growth, the plant was extracted using a solution of 1:1 methanol:water to speciate arsenic with high-performance liquid chromatography–inductively coupled plasma mass spectrometry. Almost all arsenic was present as relatively toxic inorganic forms, with little detectable organoarsenic species4. The concentration of As(III) was greater in the fronds (47–80%) than in the roots %), indicating that As(V)was converted to As(III) during translocation from roots to fronds.As well as removing arsenic from soils containing different concentrations of arsenic (Table 1), brake fern also removed arsenic from soils containing different arsenic species (Fig. 1c). Again, up to 93% of the arsenic was concentrated in the fronds. Although both FeAsO4 and AlAsO4 are relatively insoluble in soils1, brake fern hyperaccumulated arsenic derived from these compounds into its fronds (136–315 levels 3–6 times greater than soil arsenic.Brake fern is mesophytic and is widely cultivated and naturalized in many areas with a mild climate. In the United States, it grows in the southeast and in southern California5. The fern is versatile and hardy, and prefers sunny (unusual for a fern) and alkaline environments (where arsenic is more available). It has considerable biomass, and is fast growing, easy to propagate,and perennial.We believe this is the first report of significant arsenic hyperaccumulation by an unmanipulated plant. Brake fern has great potential to remediate arsenic-contaminated soils cheaply and could also aid studies of arsenic uptake, translocation, speciation, distribution anddetoxification in plants.*Soil and Water Science Department, University ofFlorida, Gainesville, Florida 32611-0290, USAe-mail†Cooperative Extension Service, University ofGeorgia, Terrell County, PO Box 271, Dawson,Georgia 31742, USA‡Department of Chemistry & SoutheastEnvironmental Research Center, FloridaInternational University, Miami, Florida 33199,1. Nriagu, J. O. (ed.) Arsenic in the Environment Part 1: Cycling and Characterization (Wiley, New York, 1994).2. Brooks, R. R. (ed.) Plants that Hyperaccumulate Heavy Metals (Cambridge Univ. Press, 1998).3. Kabata-Pendias, A. & Pendias, H. in Trace Elements in Soils and Plants 203–209 (CRC, Boca Raton, 1991).4. Koch, I., Wang, L., Ollson, C. A., Cullen, W. R. & Reimer, K. J. Envir. Sci. Technol. 34, 22–26 (2000).5. Jones, D. L. Encyclopaedia of Ferns (Lothian, Melbourne, 1987).积累砷的蕨类植物耐寒，多功能，生长快速的植物，有助于从污染土壤去除砷有毒和致癌的土壤砷污染是非常广泛的。
英文文献及翻译(计算机专业)
英文文献及翻译(计算机专业)The increasing complexity of design resources in a net-based collaborative XXX common systems。
design resources can be organized in n with design activities。
A task is formed by a set of activities and resources linked by logical ns。
XXX managementof all design resources and activities via a Task Management System (TMS)。
which is designed to break down tasks and assign resources to task nodes。
This XXX。
2 Task Management System (TMS)TMS is a system designed to manage the tasks and resources involved in a design project。
It poses tasks into smaller subtasks。
XXX management of all design resources and activities。
TMS assigns resources to task nodes。
XXX。
3 Collaborative DesignCollaborative design is a process that XXX a common goal。
In a net-based collaborative design environment。
n XXX n for all design resources and activities。
英文文献翻译
Preparation and characterization of Ag-TiO2 hybrid clusters powders[1]（Ag-TiO2混合团簇粉末的制备和表征）Abstract：液相电弧放电法被用于制备纳米Ag-TiO2复合超细粉末。
XRD和TEM图表明颗粒呈葫芦状形态，分布狭窄。
我们讨论了实验条件对产品的影响，比较了这种方法制备的粉末和其他γ射线辐照法制备的粉末。
Introduction：材料合成技术，提高了研究特定电子和光学特性的能力。
这也导致了设备和不同效应的快速发展，如集成光学型偏振器[1]和量子霍耳效应。
所需的长度尺度对于这些结构的控制是在纳米级别的[ 2 ]。
科学家面临的一个新的挑战是半导体量子点的生长，它具有新的光学响应，引起了对其基础物理方面和三阶非线性光致发光的应用等的研究兴趣。
这方面的一个例子是Ag-TiO2复合材料通过胶体方法合成[ 3 ]或由γ射线辐照法合成[ 4 ]。
对比其他制备超细金属颗粒的方法，γ射线辐照法能在室温的环境压力下产生粉末。
在这封信中，我们开发了一种新的方法，即液相电弧放电法，用以制备纳米复合材料，当它经水热处理可以得到纳米级别的超细粉。
Preparation and photocatalytic activity of immobilized composite photocatalyst (titania nanoparticle/activated carbon)[2]固定化复合光催化剂（TiO2纳米颗粒/活性炭）的制备和光催化活性研究Abstract：制备了一种固定化复合光催化剂——TiO2纳米颗粒/活性炭（AC），并研究了它在降解纺织染料的光催化活性。
AC通过油菜籽壳制备。
碱性红18（BR18）和碱性红46（BR46）被用来作为模型染料。
并采用了傅里叶变换红外（FTIR），波长色散X射线光谱（WDX），扫描电子显微镜（SEM），紫外可见分光光度法，化学需氧量（COD）和离子色谱（IC）分析。
中英文文献翻译
Database introduction and ACCESS2000The database is the latest technology of data management, and the important branch of computer science. The database , as its name suggests, is the warehouse to preserve the data. The warehouse to store apparatus in computer only, and data to deposit according to sure forms。
The so-called database is refers to the long-term storage the data acquisition which in the computer, organized, may share。
In the database data according to the certain data model organization, the description, and the storage, has a smaller redundance, the higher data independence and the easy extension, and may altogether shine for each kind of user。
The effective management database, frequently has needed some database management systems (DBMS) is the user provides to database operation each kind of order, the tool and the method, including database establishment and recording input, revision, retrieval, demonstration, deletion and statistics。
毕业论文英文文献翻译
毕业论文英文文献翻译The translation of a 700-word English literature for a graduation thesis would take a considerable amount of time and effort. Due to limitations in this platform, it is not feasible to provide a high-quality translation within the given word count.However, I can provide you with some guidelines and key points that can help you translate the literature on your own:1. Read the literature thoroughly and understand its main arguments and ideas.2. Make a list of keywords and important terms mentioned in the literature.3. Research the keywords and terms to understand their accurate translations in your target language.4. Identify the main structure and flow of the literature.5. Start translating paragraph by paragraph, making sure to preserve the original meaning and tone of the text.6. Use appropriate transition words and phrases to ensure coherence and logical progression in your translation.7. Proofread and revise your translation multiple times to correct any grammatical or syntactical errors.It is crucial to note that translating academic literature requires a deep understanding of the subject matter and proficiency in both languages. If you are not confident in your translation skills, it might be wise to seek professional help or consult a native speaker proficient in both languages.Remember that the translation of academic literature is animportant step in any graduation thesis, so it's essential to give ample time and attention to the task.。
中英文文献以及翻译(化工类)
Foreign material：Chemical Industry1.Origins of the Chemical IndustryAlthough the use of chemicals dates back to the ancient civilizations, the evolution of what we know as the modern chemical industry started much more recently. It may be considered to have begun during the Industrial Revolution, about 1800, and developed to provide chemicals roe use by other industries. Examples are alkali for soapmaking, bleaching powder for cotton, and silica and sodium carbonate for glassmaking. It will be noted that these are all inorganic chemicals. The organic chemicals industry started in the 1860s with the exploitation of William Henry Perkin’s discovery if the first synthetic dyestuff—mauve. At the start of the twentieth century the emphasis on research on the applied aspects of chemistry in Germany had paid off handsomely, and by 1914 had resulted in the German chemical industry having 75% of the world market in chemicals. This was based on the discovery of new dyestuffs plus the development of both the contact process for sulphuric acid and the Haber process for ammonia. The later required a major technological breakthrough that of being able to carry out chemical reactions under conditions of very high pressure for the first time. The experience gained with this was to stand Germany in good stead, particularly with the rapidly increased demand for nitrogen-based compounds (ammonium salts for fertilizers and nitric acid for explosives manufacture) with the outbreak of world warⅠin 1914. This initiated profound changes which continued during the inter-war years (1918-1939).Since 1940 the chemical industry has grown at a remarkable rate, although this has slowed significantly in recent years. The lion’s share of this growth has been in the organic chemicals sector due to the development and growth of the petrochemicals area since 1950s. The explosives growth in petrochemicals in the 1960s and 1970s was largely due to the enormous increase in demand for synthetic polymers such as polyethylene, polypropylene, nylon, polyesters and epoxy resins.The chemical industry today is a very diverse sector of manufacturing industry, within which it plays a central role. It makes thousands of different chemicals whichthe general public only usually encounter as end or consumer products. These products are purchased because they have the required properties which make them suitable for some particular application, e.g. a non-stick coating for pans or a weedkiller. Thus chemicals are ultimately sold for the effects that they produce.2. Definition of the Chemical IndustryAt the turn of the century there would have been little difficulty in defining what constituted the chemical industry since only a very limited range of products was manufactured and these were clearly chemicals, e.g., alkali, sulphuric acid. At present, however, many intermediates to products produced, from raw materials like crude oil through (in some cases) many intermediates to products which may be used directly as consumer goods, or readily converted into them. The difficulty cones in deciding at which point in this sequence the particular operation ceases to be part of the chemical industry’s sphere of activities. To consider a specific example to illustrate this dilemma, emulsion paints may contain poly (vinyl chloride) / poly (vinyl acetate). Clearly, synthesis of vinyl chloride (or acetate) and its polymerization are chemical activities. However, if formulation and mixing of the paint, including the polymer, is carried out by a branch of the multinational chemical company which manufactured the ingredients, is this still part of the chemical industry of does it mow belong in the decorating industry?It is therefore apparent that, because of its diversity of operations and close links in many areas with other industries, there is no simple definition of the chemical industry. Instead each official body which collects and publishes statistics on manufacturing industry will have its definition as to which operations are classified as the chemical industry. It is important to bear this in mind when comparing statistical information which is derived from several sources.3. The Need for Chemical IndustryThe chemical industry is concerned with converting raw materials, such as crude oil, firstly into chemical intermediates and then into a tremendous variety of other chemicals. These are then used to produce consumer products, which make our livesmore comfortable or, in some cases such as pharmaceutical produces, help to maintain our well-being or even life itself. At each stage of these operations value is added to the produce and provided this added exceeds the raw material plus processing costs then a profit will be made on the operation. It is the aim of chemical industry to achieve this.It may seem strange in textbook this one to pose the question “do we need a chemical industry?” However trying to answer this question will provide(ⅰ) an indication of the range of the chemical industry’s activities, (ⅱ) its influence on our lives in everyday terms, and (ⅲ) how great is society’s need for a chemical industry. Our approach in answering the question will be to consider the industry’s co ntribution to meeting and satisfying our major needs. What are these? Clearly food (and drink) and health are paramount. Other which we shall consider in their turn are clothing and (briefly) shelter, leisure and transport.(1)Food. The chemical industry makes a major contribution to food production in at least three ways. Firstly, by making available large quantities of artificial fertilizers which are used to replace the elements (mainly nitrogen, phosphorus and potassium) which are removed as nutrients by the growing crops during modern intensive farming. Secondly, by manufacturing crop protection chemicals, i.e., pesticides, which markedly reduce the proportion of the crops consumed by pests. Thirdly, by producing veterinary products which protect livestock from disease or cure their infections.(2)Health. We are all aware of the major contribution which the pharmaceutical sector of the industry has made to help keep us all healthy, e.g. by curing bacterial infections with antibiotics, and even extending life itself, e.g. ß–blockers to lower blood pressure.(3)Clothing. The improvement in properties of modern synthetic fibers over the traditional clothing materials (e.g. cotton and wool) has been quite remarkable. Thus shirts, dresses and suits made from polyesters like Terylene and polyamides like Nylon are crease-resistant, machine-washable, and drip-dry or non-iron. They are also cheaper than natural materials.Parallel developments in the discovery of modern synthetic dyes and the technology to “bond” th em to the fiber has resulted in a tremendous increase in the variety of colors available to the fashion designer. Indeed they now span almost every color and hue of the visible spectrum. Indeed if a suitable shade is not available, structural modification of an existing dye to achieve this canreadily be carried out, provided there is a satisfactory market for the product.Other major advances in this sphere have been in color-fastness, i.e., resistance to the dye being washed out when the garment is cleaned.(4)Shelter, leisure and transport. In terms of shelter the contribution of modern synthetic polymers has been substantial. Plastics are tending to replace traditional building materials like wood because they are lighter, maintenance-free (i.e. they are resistant to weathering and do not need painting). Other polymers, e.g. urea-formaldehyde and polyurethanes, are important insulating materials f or reducing heat losses and hence reducing energy usage.Plastics and polymers have made a considerable impact on leisure activities with applications ranging from all-weather artificial surfaces for athletic tracks, football pitches and tennis courts to nylon strings for racquets and items like golf balls and footballs made entirely from synthetic materials.Like wise the chemical industry’s contribution to transport over the years has led to major improvements. Thus development of improved additives like anti-oxidants and viscosity index improves for engine oil has enabled routine servicing intervals to increase from 3000 to 6000 to 12000 miles. Research and development work has also resulted in improved lubricating oils and greases, and better brake fluids. Yet again the contribution of polymers and plastics has been very striking with the proportion of the total automobile derived from these materials—dashboard, steering wheel, seat padding and covering etc.—now exceeding 40%.So it is quite apparent even from a brief look at the chemical industry’s contribution to meeting our major needs that life in the world would be very different without the products of the industry. Indeed the level of a country’s development may be judged by the production level and sophistication of its chemical industry4. Research and Development (R&D) in Chemical IndustriesOne of the main reasons for the rapid growth of the chemical industry in the developed world has been its great commitment to, and investment in research and development (R&D). A typical figure is 5% of sales income, with this figure being almost doubled for the most research intensive sector, pharmaceuticals. It is important to emphasize that we are quoting percentages here not of profits but of sales income, i.e. the total money received, which has to pay for raw materials, overheads, staff salaries, etc. as well. In the past this tremendous investment has paid off well, leading to many useful and valuable products being introduced to the market. Examplesinclude synthetic polymers like nylons and polyesters, and drugs and pesticides. Although the number of new products introduced to the market has declined significantly in recent years, and in times of recession the research department is usually one of the first to suffer cutbacks, the commitment to R&D remains at a very high level.The chemical industry is a very high technology industry which takes full advantage of the latest advances in electronics and engineering. Computers are very widely used for all sorts of applications, from automatic control of chemical plants, to molecular modeling of structures of new compounds, to the control of analytical instruments in the laboratory.Individual manufacturing plants have capacities ranging from just a few tones per year in the fine chemicals area to the real giants in the fertilizer and petrochemical sectors which range up to 500,000 tonnes. The latter requires enormous capital investment, since a single plant of this size can now cost $520 million! This, coupled with the widespread use of automatic control equipment, helps to explain why the chemical industry is capital-rather than labor-intensive.The major chemical companies are truly multinational and operate their sales and marketing activities in most of the countries of the world, and they also have manufacturing units in a number of countries. This international outlook for operations, or globalization, is a growing trend within the chemical industry, with companies expanding their activities either by erecting manufacturing units in other countries or by taking over companies which are already operating there.化学工业1.化学工业的起源尽管化学品的使用可以追溯到古代文明时代，我们所谓的现代化学工业的发展却是非常近代（才开始的）。
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中等分辨率制备分离的
快速色谱技术
W. Clark Still,* Michael K a h n , and Abhijit Mitra Departm(7nt o/ Chemistry, Columbia
Uniuersity,1Veu York, Neu; York 10027
ReceiLied January 26, 1978
我们希望找到一种简单的吸附色谱技术用于有机化合物的常规净化。
这种技术是适于传统的有机物大规模制备分离，该技术需使用长柱色谱法。
尽管这种技术得到的效果非常好，但是其需要消耗大量的时间，并且由于频带拖尾经常出现低复原率。
当分离的样本剂量大于1或者2g时，这些问题显得更加突出。
近年来，几种制备系统已经进行了改进，能将分离时间减少到1-3h，并允许各成分的分辨率ΔR f≥（使用薄层色谱分析进行分析）。
在这些方法中，在我们的实验室中，媒介压力色谱法1和短柱色谱法2是最成功的。
最近，我们发现一种可以将分离速度大幅度提升的技术，可用于反应产物的常规提纯，我们将这种技术称为急骤色谱法。
虽然这种技术的分辨率只是中等（ΔR f≥），而且构建这个系统花费非常低，并且能在10-15min内分离重量在的样本。
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急骤色谱法是以空气压力驱动的混合介质压力以及短柱色谱法为基础，专门针对快速分离，介质压力以及短柱色谱已经进行了优化。
优化实验是在一组标准条件5下进行的，优化实验使用苯甲醇作为样本，放在一个20mm*5in.的硅胶柱60内，使用Tracor 970紫外检测器监测圆柱的输出。
分辨率通过持续时间（r）和峰宽（w,w/2）的比率进行测定的（Figure 1），结果如图2-4所示，图2-4分别放映分辨率随着硅胶颗粒大小、洗脱液流速和样本大小的变化。
从这些数据中间，我们可以得出许多有趣的事实。
首先，我们发现最常使用的硅胶60的大小——70-230区间（63-200μm ）在标准条件下产生的分辨率在所有被研究的数据中是最低的。
第二，在我们使用的包装方法下，颗粒的大小小于40μm 并不能提高分辨率。
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柱效能对洗脱率的变化是相当敏感的，并且最好是用相对较高的洗脱液流速。
在乙酸乙酯/石油醚的混合物中（30-60℃），吸附床上的溶剂的头应该以±./min 的速度落下，这样才能得到最佳的分辨率。
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最后，从峰值的宽度可以看出，随着样本的减少，分辨率呈现出预期的增加。
样本的回收率≥95%。
这项技术所需要的设备包括一组色谱柱和阀门流量控制器（上图）。
该色谱柱是一个拥有一个18in.的扁平底部，配有一个聚四氟乙烯活塞以及一个24/40玻璃接头的玻璃管。
比起标
准的多孔圆底，没有多孔玻璃床支持的色谱柱
通常更受欢迎，因为它们显著地减少了死腔。
流量控制器阀是一个能精确调节洗脱率的简单可变的液体排放装置，由一个玻璃/聚四氟乙烯针阀（Ace Glass Co. No. 8193-04 或相同性能的替代物）和一个标准的24/40接头组成。
详细的实验过程将在会在实验部分陈述。
实验过程简单介绍如下：（1）溶剂应该能够提供良好的分离，并且能将所需成分提高到R f =（薄层色谱分析，E. Merck No. 5765）。
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（2）需要合适参数（见Table Ⅰ）的色谱柱，色谱柱中装有5-6in.的40-63μm 的干燥硅胶（ ）。
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（3）色谱柱内装满了溶剂，内部的压力能迅速将硅胶中所有的空气排空。
（4）加入样本，再用溶剂将色谱柱注满，在2 in./min 的流速下洗脱。
洗脱色谱柱所需成分的时间一般非常快（5-10min ），因此我们已经抛弃了自动馏分收
集器，取而代之的是放在架子上的40支20*150试管。
小的部分通常只在洗脱早期早期进行收集，较大部分会从色谱分析的早期一直收集到最后。
通过沿着7cm*薄层色谱板的长边以~5μL 为单位进行定点测量，之后再沿着侧板测量，可以方便的检测分离组件。
小样本或者高度保持的组件可能需要用到重定位。
Figure6显示了一个典型的分离。
在过去的一年里，我们已经尝试了数以百计的色谱柱。
在任何情况下，我们已经能够做到将完全分离ΔR f≥的混合物在15min内完全分离，许多情况ΔR f≈也是可以的。
在给定的色谱柱中使用的样本数量与它的横截面积成正比，Table Ⅰ能作为色谱柱选择的指南。
如果分辨率要求不高，样本量可以大幅度增加；我们使用一个50-mm的色谱柱来对重量大于10g、ΔR f≥的混合物进行纯化。
甚至在直径大的色谱柱中，分辨率也能维持在一个能接受的标准。
比如差向异构体的乙醇1和2的R f 分别为和，放入5%的乙酸乙酯/石油醚中。
1和2的混合物（ΔR f=）在直径为40-mm的色谱柱中能在7min内与65-mg混合部分（500mL 5%的乙酸乙酯 /石油醚）轻松的被分开。
如果被分离的组件在薄层色谱法中ΔR f小于，使用更长（例如，10in.）的硅胶色谱柱或者使用极性较小的溶剂能提高分辨率。
可以使用在薄层色谱法中R f=溶剂去移动所需成分，这样不会大幅度提高洗脱时间。
不论哪种情况，色谱柱应该只能轻轻地装满样品，并且应该将流速维持在2 in./min。
很明显，在乙酸乙酯/石油醚混合物中，低流速会造成分辨率降低。
总之，急骤层析为只需要中等分辨率的混合物制备分离提供了一个快速且便宜的常规方法。
甚至在需要高分辨率时，使用快速技术作为初步净化能简化高分辨率的分离，从而避免了昂贵的高效液相色谱柱的污染。
最后，我们想要强调这样一个事实，在这个方法中，使用40-63μm的硅胶和使用压力（而不是真空）驱使流率达./min对于成功分离是至关重要的。
实验部分
将色谱柱和流量控制器阀进行组装，组装方式如前所述。
硅胶材料选用40-63μm （400-230 mesh）硅胶60（E. Merck No. 9385）。
10溶剂在使用之前需要被蒸馏。
薄层色谱会在玻
璃支持的硅胶60板上进行（厚，F-254）（ No. 5765）。
急骤层析技术的一般过程。
首先应该找到一个低粘度溶剂系统（例如，乙酸乙酯/30-60℃石油醚）8，这个系统能分离混合物并且能移动所需成分，使得所需成分在薄层色谱分析上的R f为。
如果几种在薄层色谱分析上非常相近的化合物需要分开，调整溶剂，在R f=时使得中间点在所有混合物之间。
如果这些化合物是广泛分散的，将活动较小成分的R f调整到。
在选好合适的溶剂之后，需要挑选合适直径的色谱柱（在文中，Table Ⅰ），并将一个玻璃棉制成的小塞子放置在试管中，用于连接活塞和色谱柱的体部（上面图中的A）。
两个可伸缩的玻璃管（6和8 mm .）使得玻璃棉塞子的位置易于调整。
接下来，一个由50-100 mesh沙组成的 1/8 in.的光滑层覆盖在色谱柱的底部，将40-63μm的干硅胶倒入色谱柱单独的部分内，深度为.随着活塞打开，将色谱柱轻轻地垂直于桌面拔出，直至包裹凝胶。
之后将一个1/8 in.的沙层干凝胶床的平面顶部，夹紧色谱柱以便加压填充和包裹。
将之前选择的溶剂在从沙的上面小心的倒入并完全填充色谱柱。
流量控制器的调流调压阀（B）一直是打开的，流量控制器是紧密安装在色谱柱的顶部，并由强大的橡皮筋加固。
控制流量控制器的主要空气线阀是轻微打开的，一个手指必须严格地放置在泄放孔（C）。
硅胶的顶部必须持续保持湿润。
接下来用移液管将样品（在洗脱液中为20-25%的溶液）从吸附床的顶部加入，流控制器暂时地放在色谱柱的顶部，以便驱动所有的样品进入硅胶。
11通常用包裹色谱柱的溶剂来洗涤色谱柱。
色谱柱壁用几毫升新鲜洗涤液进行冲洗，冲洗之后的液体像之前一样被推入凝胶中，色谱柱内完全被填满了洗涤液以便不能扰乱吸附床。
流量控制器最终被固定在色谱柱上，调整色谱柱中溶剂的表面以 in./min的速度下滑。
颗粒直径在40-63μm时，对于大多数低粘度的溶剂这似乎是流速的最佳值。
所有的溶剂用完之前，部分一直在被收集（溶剂的量和分数的大小参考Table Ⅰ）。
最好保持色谱柱湿润，因为进一步的洗涤偶尔是有必要的。
纯化组件和之前描述一样。
如果严格遵守之前的介绍的操作流程，几乎不可能分离失败。
虽然我们一般为每次分离包装新鲜色谱柱，但是大规模分离的花费使得它有利于重用大直径色谱柱。
色谱柱的重复使用受第一次冲洗的影响（速率=2in./min），第一次冲洗首先用大约5in.的洗涤液（通常是乙酸乙酯或丙酮）中极性更大的成分冲洗，然后用5in.所需洗涤液冲洗。
如果洗提液相对非极性的（比如小于10%乙酸乙酯/石油醚），使用冲洗溶剂（比如小
于20-50%乙酸乙酯/石油醚）可能更明智，冲洗溶剂比起纯高极性成分极性稍微小一些。
参照和注释
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