Effect of growth conditions on the rheological properties and chemical composition ofVolcaniella eurihalina exopolysaccharide

The exopolysaccharide produced byVolcaniella eurihalina, an halophilic eubacterium, under different environmental and nutritional conditions, is studied.V. eurihalina synthesizes an acidic heteropolysaccharide, composed by rhamnose, glucose, and mannose, as well as amino sugars, uronic acids, and acetyl and sulphate residues. This composition varies depending on the nutrients of culture medium. Viscosity and pseudoplasticity of the polymer solutions are also influenced by the nutritional conditions in which the microorganism was grown.     

卤代化合物的光化学反应研究进展

介绍近年来卤代化合物在光照射下的偶联反应、醇解反应、消去反应、开环反 应，尤其是卤代杂环化合物的光化学反应，得到了许多用热反应或催化反应无法替 代的具有生物(理)活性的中间体．     

Crystal Structure of (6S,9S,13R,14S)-7,8-Didehydro-3,7-dimethoxy-17-methylmorphinan-4,6-diol

1 INTRODUCTION (9S,13R,14S)-7,8-Didehydro-3,7-dimethoxy-4-hydroxy-17-methylmorphinan-6-one I is an impor- tant natural product that was used to ease pain, decrease blood pressure and diminish inflammation. In order to study the stereochemistry of the reduction of I with potassium boronhydride, the crystal structure of the title compound II was determined by X-ray diffraction method. 2 EXPERIMENTAL 2. 1 Instrument The melting point was measured on a Yanagimoto MP-500 apparatus…     

A numerical method using the Prfer transformation for the calculation of eigenpairs of two-parameter Sturm-Liouville problems

A shooting method for coupled Prfer equations is discussedfor numerical solution of two-parameter Sturm-Liouville problems. Research supported in part by grants from the NSERC of Canada.     

Synthesis and Photochromic Properties of Azido Analogues ofSpiropyran and Spirooxazine as Nucleic Acid Labeling Reagent

A series of photo active azido analogues have been synthesized and their photochromic properties have also been investigated by UV-Vis spectrum. It will be used for the rapid and reliable preparation of large amounts of stable, non-radioactive labeled DNA and RNA hybridization probes. And it is supposed to be easily detected for its photochromic properties.     

Ni／γ—Al2O3,Ni／MgO,Ni／SiO2催化剂上甲烷与二氧化碳重整反应的研究

采用ＸＲＤ，ＵＶ－ＤＲＳ，ＸＰＳ，ＴＰＲ，Ｈ２－Ｏ２滴定和吡啶吸附－红外光谱等技术，研究了负载于具有不同酸碱性的γ－Ａｌ２Ｏ３，ＳｉＯ２，Ｍｇｏ载体上的镍催化剂表面物理化学性质，及其对甲烷与二氧化碳重整制取合成气反应催化活性的影响。结果表明，在上述负载型镍催化剂上，影响重整反应活性和积炭量的主要原因不是催化剂表面酸碱性，而是金属镍在催化剂表面的分散度。     

微波辐射下无催化剂一锅法合成N-甲基十氢吖啶-1,8-二酮化合物

为了研究从简单易得的原料在无催化剂的条件下一锅法合成N-甲基十氢吖啶-1,8-二酮化合物，我们以各类醛（脂肪醛、芳香醛、二醛）、达咪酮或1,3-环己二酮和甲胺为原料，以乙二醇或水为溶剂，经微波辐射，一步反应得到了一系列N-甲基十氢吖啶-1,8-二酮化合物。反应时间从传统热反应的4-5小时缩短至2-10分钟，产率较高（56-95%），并且不需要使用催化剂。该反应后处理方便，只需要简单洗涤，环境友好，为合成此类化合物提供了一种简便、有效的合成方法。该方法不仅适用于一元脂肪醛、芳香醛，还适用于芳香二醛，因此可以合成含有一个或两个十氢吖啶结构单元的杂环化合物。     

Aa1Dd1-Aa2Dd2型氢键体系的网络结构参数

利用溶胶-凝胶分配理论对氢键溶液的模型体系进行研究, 给出了体系的凝胶化条件以及凝胶点后氢键网络中各类结构参数的计算方案, 并进行了相应的数值计算. 结果表明, 当两类质子受体基团的活性不同时, 质子受体基团的竞争作用对网络结构有一定影响. 这为控制氢键网络结构特征提供了可能的理论线索.     

Facile Ionic Liquids-Promoted One-Pot Synthesis of Polyhydroquinoline Derivatives under Solvent Free Conditions

In recent years, much attention has been directed towards the syntheses of 1,4-dihydropyridyl compounds due to the fact that 1,4-dihydropyridyl compounds possess a variety of biological activities.[1] In view of the importance of polyhydroquinoline derivatives, many classical methods for the synthesis of polyhydroquinoline derivatives were reported[2] by conventional heating and refluxing approaches in the presence of organic solvent. These methods, however, involve long reaction time, harsh reaction conditions, the use of a large quantity of organic solvent and unsatisfactory yields. Therefore,improvements in such syntheses have been sought continuously.