一类相变的Landau-deGennes模型——高斯近似

本文对一类相变的Landau-deGennes模型(以下简称L-deG模型)进行了高斯近似和平均场近似计算,获得一些“临界指数”的数值。例如,在高斯近似下,α=0.5≠α＇,γ=1≠γ＇,ν=0.5≠ν＇等等。我们计算了比热,并与液晶MBBA的实验进行了比较,讨论了向列相-各向同性液相相变与三重临界点的关系。文中特别着重讨论了一类与二类相变临界行为的异同。我们认为,二类相变的标度律结果不能简单地挪用到一类相变的情况。     

毒蕈碱受体激动剂的三维定量构效关系研究

采用比较分子场分析法(CoMFA)研究了55个四氢吡啶类毒蕈碱受体激动剂的三维定量构效关系(3D-QSAR), 建立了具有较强预测能力的3D-QSAR模型. 所得模型的交叉验证相关系数(q²)为0.507, 常规相关系数(R²)为0.982 , 标准方差为0.218, 说明系列化合物分子周围立体场和静电场的分布与生物活性间存在良好的相关性. 模型不仅很好地预测了训练集和测试集化合物的活性, 而且为设计活性更高的受体激动剂提供了理论依据.     

3－苯氧甲基－6－（2，4－二氟苯基）－7H-1,2,4-三唑并[3,4-b][1,3,4]噻二嗪的合成与晶体结构研究

由苯氧乙酸出发，经多步反应，制得3-苯氧甲基－4－氨基－5－巯基－1，2， 4－三唑，它与2-氯－2'，4'－二氟苯乙酮进行环化反应，生成3-苯氧甲基－6－（ 2,4-二氟苯基）－7H-1,2,4-三唑并[3,4-b][1,3,4]噻二嗪，通过元素分析、红外 光谱、核磁共振氢谱与碳谱、质谱进行表征，并利用单晶X射线衍射法测定其结构 。晶体属单斜晶系、P2_(1/c)空间群，a = 1.339(3) nm, b = 1.4683(4) nm, c = 0.8606(2) nm, β = 108.49(2)°, Z = 4, F(000) = 736, R_1 = 0.0509。还 对均三唑并噻二唑两类稠杂环的晶体结构作了比较。     

离子液体[BMim]BF4对SDS水溶液表面活性和聚集能力的促进

采用表面张力测定法和核磁共振谱等方法研究了阴离子表面活性剂十二烷基硫酸钠(SDS)在水溶性室温离子液体[BMim]BF4/水混合溶剂中的表面性质及聚集行为, 发现极少量[BMim]BF4的介入就可以显著降低SDS的临界胶束浓度, 提高体系的表面活性; 且[BMim]BF4在混合溶剂中所占的摩尔分数(x1)在一定范围内(0相似文献   

二氧化钒和三氧化二钒研究进展

VO₂和V₂O₃是优异的光、电、磁热敏材料，在多种技术领域中具有广阔的应用前景，已成为国内外新颖功能材料研究的热点之一。本文综述了VO₂和V₂O₃的粉体、陶瓷和薄膜的研究进展，并对相关问题进行讨论。     

The Synthesis of Gracillin and Dioscin：TWO Typical Representatives of Spirostanol Glycosides

Two spirostanol saponins(gracillin and dioscin)which have the typical sugar moieties were synthesized facilely by a general approach.     

Solid Phase Catalytic Oxidation of Alcohols by Polymer Supported Rare Earth Catalysts

Oxidation of alcohols to the corresponding aldehydes or ketones is one of the most fundamental reactions in organic chemistry [1,2]. Some of the products of the oxidation exhibit an important role in the organic synthesis as well as pharmaceutical synthesis. In most reactions, the lanthanide complexes show satisfied catalytic activities for some compounds. Furthermore, there has been increasing interest in the lanthanide complexes and several reports have appeared in the literature [3, 4]. But the exploitation of these complexes for the oxidation of some organic substrates has been limited. Here we reported a method for the preparation and the catalytic properties as well as the recycling of lanthanide complexes in oxidation of alcohols.The synthetic procedure for the polymer supported lanthanide complexes is shown as following(scheme 1):●-NH2+CICH2COOH(C2Hs)3N→●-NHCH2COOHM=Ce(Ⅲ), Tb(Ⅲ), Sm(Ⅲ)scheme 1The oxidation of benzyl alcohol was carried out in the presence of iodosylbenzene by the polymer supported Ce(Ⅲ), Tb(Ⅲ) and Sm(Ⅲ) catalysts at 80℃ for 4.0h, the yields of benz-aldehyde are as following (table 1):Table 1 Oxidation of benzyl alcohol with the supported catalysts**Reaction condition: benzyl alcohol 0.1 mmol, iodosylbenzene 0.15mmol,catalyst 0.2mg, 80℃ for 4.0h in 1,2-dichloroethane.It can be seen from the table that the Tb(Ⅲ) complex shows higher catalytic activity for the oxidation of benzyl alcohol. Further investigation is now being carded on to optimize the results.     

3-RRRT并联机器人插补算法及其误差分析

结合3-RRRT并联机器人数控系统的开发，提出了粗、精插补策略和算法，研究了插补误差的分布规律．结果表明，在3-RRRT并联机器人数控系统中，精插补误差可以忽略不计.     

新型功能染料1,1''''-二正丁基-3,3,3'''',3''''-四甲基吲哚三碳菁高氯酸盐的合成及表征

采用DMF为溶剂合成得到1,1'-二正丁基-3,3,3',3'-四甲基吲哚三碳菁,并利用IR、HNMR进行了结构表征.测定了该化合物的吸收光谱,其最大吸收波长为λmax=747.5 nm,半峰宽为50.4 nm,摩尔消光系数高达2.44×105lcm-1mol-1.     

TiO2薄膜光催化降解二氯乙酸和三氯乙酸水溶液

用常压化学气相沉积法镀TiO2薄膜,以紫外灯为光源,对二氯乙酸和三氯乙酸溶液进行光催化降解,并证实了此过程符合一级反应动力学方程。结果表明:卤代度以及不同的半导体化合物底物均对二氯乙酸和三氯乙酸溶液的降解有影响,卤代度低的二氯乙酸比卤代度高的三氯乙酸降解效果要好;同样条件下半导体的带隙能越低,降解效果越好。