The effectiveness of Web search engines for retrieving relevant ecommerce links

Ecommerce is developing into a fast-growing channel for new business, so a strong presence in this domain could prove essential to the success of numerous commercial organizations. However, there is little research examining ecommerce at the individual customer level, particularly on the success of everyday ecommerce searches. This is critical for the continued success of online commerce. The purpose of this research is to evaluate the effectiveness of search engines in the retrieval of relevant ecommerce links. The study examines the effectiveness of five different types of search engines in response to ecommerce queries by comparing the engines’ quality of ecommerce links using topical relevancy ratings. This research employs 100 ecommerce queries, five major search engines, and more than 3540 Web links. The findings indicate that links retrieved using an ecommerce search engine are significantly better than those obtained from most other engines types but do not significantly differ from links obtained from a Web directory service. We discuss the implications for Web system design and ecommerce marketing campaigns.     

Optimization of technological conditions for one-pot synthesis of (S)-α-cyano-3-phenoxybenzyl acetate in organic media

Optically active form of α-cyano-3-phenoxybenzyl (CPB) alcohol, building block of pyrethroid insecticides, was synthesized as its acetate by the combination of anion-exchange resin (D301)-catalyzed transcyanation between m-phenoxybenzaldehyde (m-PBA) and acetone cyanohydrin (AC), and lipase (from Alcaligenes sp.)-catalyzed enantioselective transesterification of the resulting cyanohydrin with vinyl acetate. Through optimizing technological conditions, the catalyzing efficiency was improved considerably compared to methods previously reported. Concentrations of CPB acetate were determined by gas chromatograph. The enantio excess (e.e.) values of CPB acetate were measured by NMR (nuclear magnetic resonance) method. Effects of solvents and temperatures on this reaction were studied. Cyclohexane was shown to be the best solvent among the three tested solvents. 55 ℃ was the optimal temperature for higher degree of conversion. External diffusion limitation was excluded by raising the rotational speed to 220 r/min. However, internal diffusion could not be ignored, since the catalyst (lipase) was an immobilized enzyme and its particle dimension was not made small enough. The reaction rate was substantially accelerated when the reactant (m-PBA) concentration was as high as 249 mmol/L, but decreased when the initial concentration of m-PBA reached to 277 mmol/L. It was also found that the catalyzing capability of recovered lipase was high enough to use several batches. Study of the mole ratio of AC to m-PBA showed that 2:1 was the best choice. The strategy of adding base catalyst D301 was found to be an important factor in improving the degree of conversion of the reaction from 20% to 80%. The highest degree of conversion of the reaction has reached up to 80%.     

1-乙氧基杂氮硅三环化合物的合成及表征

以正硅酸乙酯（TEOS）和三乙醇胺为原料、氢氧化钾为催化剂、丙酮作溶剂,通过酯交换反应合成了1-乙氧基杂氮硅三环化合物,并初步探讨了反应条件的影响,并用IR对所合成的产物的结构进行了表征。     

无溶剂有机合成新进展

无溶剂条件下的有机合成,具有收率高、选择性强、操作简便、成本低及无环境污染等优点,是绿色化学的重要内容.综述了近年来发现的无溶剂有机反应类型.     

关于高师院校科技创新的思考

本文基于对高师院校科技创新及其运行机制的现状分析,通过借鉴国内外成功的科技创新组织形式的经验,提出了高师院校实现科技创新的基本途径。     

裂殖壶菌油脂提取方法的研究

比较了有机溶剂提取法、酸热法和超声波提取法对于裂殖壶菌油脂的提取能力．酸热法和超声波提取法的提取得率高于有机溶剂提取法．当氯仿和甲醇以1：1的体积比混合时,油脂提取得率最高．当氯仿和甲醇以2：1的体积比混合时,提取所得油脂中的DHA含量最高．但总提取得率还是以氯仿和甲醇的体积混合比为1：1时为最佳．     

三论中国国家创新体系的有机构成——观念与文化创新

中国国家创新体系不仅包括知识创新系统和技术创新系统，而且由于中国的国情，它还应该包括体制与制度创新系统、观念与文化创新系统和知识基础设施与管理工程系统。该文就是专论观念与文化创新系统存在的必要性和可行性。认为观念与文化落后，必定导致经济落后，要想超前发展，第一就是观念与文化创新。舍此就很难在中国发展知识经济。     

四氯化锡催化剂在精细有机合成中的应用研究进展

本文从化学反应类型出发,综述了四氯化锡催化剂在精细有机合成中的研究进展,展望了四氯化锡作为新型催化剂的发展前景。     

应用型化工专业有机化学教学案例

为了提高学生学习有机化学的兴趣和综合运用知识的能力,为应用型化工专业有机化学课程设计了一个教学案例,涉及有机化学课程的多个知识点,有助于学生对知识的全面掌握。     

离子液体的特性及其在有机物萃取中的应用

离子液体是在室温及相邻温度下完全由离子组成的有机液体物质,其性质可以通过适当选择阴离子、阳离子及其取代基而改变,因而具有一系列的优异特性。离子液体作为一种新型环保溶剂。可在萃取中发挥其优势。本文重点综述了近几年离子液体用于萃取有机物研究的最新进展。