怎样写论文摘要

除论文标题之外 ,读者是通过摘要来决定是否继续阅读整篇论文 .因而摘要是一篇论文的窗口 .要在最小的空间内阐述问题、描述方法、总结贡献 ,是需要运用技巧与经验的 .一、摘要的内容摘要 (包括中、英文摘要 )的内容应包括目的、方法、结果、结论四个部分。重点应突出文章在结果和结论方面的创新之处 .二、摘要长度中文摘要长度一般不超过 30 0字 ,不少于 2 0 0字 ;英文摘要应比中文摘要有所扩展 ,以便使非汉语读者更多地了解文章的内容 .长度一般不超过 15 0 words,不少于 10 0 words。少数情况允许例外 ,但主题概念不得遗漏 .为了使在较短…     

聚乙二醇-钍试剂-硫酸钠体系中非有机溶剂萃取光度法测定铁

本文研究了铁（Ⅲ）－ＰＥＧ（聚乙二醇－２０００）－钍试剂－Ｎａ２ＳＯ４体系的析相光度法并应用于测定Ｆｅ（Ⅲ），最适酸度为４．６（ＮａＡｃ－ＨＡｃ）缓冲溶液，其络合物的最大吸收位于５６６ｎｍ，表观摩尔吸光系数为８．０６×１０３Ｌ·ｍｏｌ－１·ｃｍ－１。Ｆｅ（Ⅲ）浓度在０—３０μｇ·ｍＬ－１范围内服从比耳定律，该方法用于发样中铁的测定，获得了满意结果     

萃取—火焰原子吸收法测定骨骼中的微量元素Cu,Zn,Cd和Fe

本文研究了以邻菲罗啉为金属螯合剂，高氯酸钠为配体，在一定酸度下用１，２－二氯乙烷萃取－火焰原子吸收法测定动物骨骼中微量Ｃｕ，Ｚｎ，Ｃｄ和Ｆｅ的条件，并确定了测定方法，方法简单，准确，可靠，元素的检测限分别为：Ｃｕ：０．０３８μｇ／ｍｌ，Ｚｎ：０．００４２μｇ／ｍｌ，Ｃｄ：０．００１９μｇ／ｍｌ，Ｆｅ：０．０２μｇ／ｍｌ，回收率在９２．８％～１０５％之间。     

Large-Scale Industrial Plant for Extraction with Supercritical Gases

Criteria for the design and construction of plant for obtaining carrier material or extracts are discussed for the example of the extraction of natural products with supercritical carbon dioxide. The parameters to be established and the course of the process in a large-scale plant are indicated. Plant engineering and optimization must be attuned to specific process-technological and construction problems.     

Separation with Supercritical Gases: Practical Applications

Extraction with supercritical gases combines, to a certain extent, the characteristics of both distillation and extraction; the term “destraction” is therefore proposed for this method of separation. The principles of the method are illustrated in this article by a series of color photographs comparing extraction and destraction. Of the practical uses of this new method may be mentioned the separation of cod-liver oil into 50 fractions, each differing in saponification value and iodine number, by means of supercritical ethane and, in particular, the decaffeination of raw coffee with supercritical carbon dioxide.     

萃取色谱法富集原子吸收法测定环境水中超痕量金属元素──两种萃取剂的比较

本文研究并比较了分别以８－羟基喹啉和巯基苯骈噻唑为萃取剂，以活性硅胶为载体的柱式萃取色谱法对环境水中Ｚｎ、Ｃｕ、Ｐｂ、Ｃｄ、Ｆｅ、Ｃｏ、Ｎｉ和Ｍｎ的最佳富集和洗脱条件。实验证明，后者明显优于前者。以巯基苯骈噻唑为萃取剂的色谱柱对金属元素的吸附具有快速、完全、寿命长和重现性好等特点。在ｐＨ＝７～８之间回收率可达９８％以上，富集倍数为２００倍。     

First isolation of a flavonoid from Juniperus procera using ethyl acetate extract

Phytochemical investigation of the ethyl acetate extract of the leaves of Juniperus procera growing in south Saudi Arabia Enemas region led to the isolation of a new flavonoid using different chromatographic methods (i.e. paper, thin layer and column chromatography). The isolated flavonoid was identified and established by m.p., ¹H-NMR, ¹³C-NMR, UV and MS spectral analysis. The isolated compound was identified as 3′,4′,3,7-tetrahydroxyflavone.     

Optimum conditions for the water extraction of L-theanine from green tea

Theanine is a unique non-protein amino acid found in tea (Camellia sinensis). It contributes to the favourable umami taste of tea and is linked to various beneficial effects in humans. There is an increasing interest in theanine as an important component of tea, as an ingredient for novel functional foods and as a dietary supplement. Therefore, optimal conditions for extracting theanine from tea are required for the accurate quantification of theanine in tea and as an efficient first step for its purification. This study examined the effects of four different extraction conditions on the yield of theanine from green tea using water and applied response surface methodology to further optimise the extraction conditions. The results showed that temperature, extraction time, ratio of water-to-tea and tea particle sizes had significant impacts on the extraction yield of theanine. The optimal conditions for extracting theanine from green tea using water were found to be extraction at 80 °C for 30 min with a water-to-tea ratio of 20:1 mL/g and a tea particle size of 0.5-1 mm.     

Determination of ethylene glycol dinitrate in dynamites using HPLC: application to the plastic explosive Goma-2 ECO

In this study, a sequential extraction method using water and methanol to recover ethylene glycol dinitrate or nitroglycol (EGDN) contained in Goma-2 ECO dynamite was developed. After, an HPLC method was used for the determination of EGDN in the two extracted phases. The analytical method was validated by evaluating its selectivity, sensitivity, linearity, and linear working concentration range, limit of detection and quantitation, precision (as repeatability and intermediate precision), accuracy, and robustness, providing appropriate values (i.e. RSD values for precision about 6% and accuracy about 100%). Finally, the EGDN content of a sample of the Goma-2-ECO dynamite was determined obtaining a concentration of 30.29%, which is in accordance with the manufacturer's specifications for this dynamite (25.7-31.4%).