中成药中微量汞的流动注射-冷原子吸收测定方法研究

研究了流动注射氢化物发生-原子吸收光谱法测定微量汞时的最佳条件,建立了中成药中微量汞的流动注射.冷原子吸收光谱分析方法。测定中成药中汞的检出限为2.7×10-9,线性范围0-60μg·L-1,相对标准偏差小于5％,加标回收率为95％-98％。方法操作简便、快速、灵敏、自动化程度高,应用于实际中成药样品中微量汞的测定,结果满意。     

Nitrogen-doped Carbon Coated Na3V2(PO4)3 with Superior Sodium Storage Capability

Cathodes with high cycling stability and rate capability are required for ambient temperature sodium ion batteries in renewable energy storage application. Na₃V₂(PO₄)₃ is an attractive cathode material with excellent electrochemical stability and fast ion diffusion coefficient within the 3D NASICON structure. Nevertheless, the practical application of Na₃V₂(PO₄)₃ is seriously hindered by its intrinsically poor electronic conductivity. Herein, solvent evaporation method is presented to obtain the nitrogen-doped carbon coated Na₃V₂(PO₄)₃ cathode material, delivering enhanced electrochemical performances. N-Doped carbon layer coating serves as a highly conducting pathway, and creates numerous extrinsic defects and active sites, which can facilitate the storage and diffusion of Na⁺. Moreover, the N-doped carbon layer can provide a stable framework to accommodate the agglomeration of the electrode upon electrode cycling. N-Doped carbon coated Na₃V₂(PO₄)₃(NC-NVP) exhibits excellent long cycling life and superior rate performances than bare Na₃V₂(PO₄)₃ without carbon coating. NC-NVP delivers a stable capacity of 95.9 mA·h/g after 500 cycles at 1 C rate, which corresponds to high capacity retention(94.6%) with respect to the initial capacity(101.4 mA·h/g). Over 91.3% of the initial capacity is retained after 500 cycles at 5 C, and the capacity can reach 85 mA·h/g at 30 C rate.     

用硅烯醚型引发剂进行的基团转移聚合

本文报道了一类硅烯醚型的基团转移聚合引发剂。并以负离子和HgI_2等为催化剂,进行了甲基丙烯酸酯和丙烯酸酯的基团转移聚合。得到了实测分子量和理论分子量相近且分散性较小的浆合物。进行了甲基丙烯酸甲酯的活性聚合以及其与丙烯酸酯的A-B-A型三嵌段共聚,证实具有活性高分子的特征。探讨了该类引发剂引发基团转移聚合的机理,研究了催化剂和引发剂的配合选择性以及催化剂和引发剂的摩尔比对产物分子量和转化率的影响,发现该类引发剂引发的基团转移聚合是一恒速聚合反应。     

A Furostanol Saponin from the Cytotoxic Fraction of Tupistra chinensis Rhizomes

More than 1800 species of medicinal plants grow in Shennongjia Forest District. Most of them were recorded to be used as anti-inflammatory agents in the folk medicine1. Kaikoujian, a Chinese name for rhizomes of Tupistra chinensis Bak., is a reputed folk …     

基团转移聚合新进展

评述了近几年来基团转移聚合在聚合单体、引发剂、催化剂、聚合实施方法及应用等方面的新进展，阐明了基团转移聚合技术在各种特定结构高分子合成中所起的重要作用。     

一种含三苯胺链段的PPV类交替共聚物的合成、表征及性能

合成了三苯胺二醛和1-甲氧基-4-辛氧基-2,5-二甲苯双(三苯基氯化)两种单体,通过Wittig反应制得了共轭聚合物,对共轭聚合物进行了表征和性能测试.这类共轭聚合物的氯仿溶液和膜在紫外光激发下能发出强的蓝绿光,与小分子三苯胺衍生物(TPD)相比,具有相对较高的热稳定性和良好的成膜性.电化学分析表明聚合物具有很好的空穴传输能力.同时对共轭聚合物的光致发光和电致发光性能进行了研究,结果表明,此聚合物与同类聚对亚苯基亚乙烯基(PPV)型聚合物相比具有较低的驱动电压和较高的发光亮度,是一种潜在的有机高分子电致发光材料.     

吸热型碳氢燃料裂解催化剂结焦研究

建立了一套可以同时进行吸热型碳氢燃料催化裂解研究和催化剂结焦评价的装置。选用SAPO－34、HZSM－5以及USY型不同孔径的分子筛催化剂对自行研制的吸热型碳氢燃料S－1进行催化裂解反应，采用注氧烧焦的方法考察了改变反应温度、反应时间等实验条件对催化剂结焦性能的影响，结果发现，当温度达到700℃时，三种催化剂都有最大的结焦量，而USY型分子筛高达55μL/mg。同时还考察了作为结焦母体的小分子烯烃在裂解产物中的分布与催化剂结焦的关系，对燃料S－1在三种分子筛上裂解结焦的规律有了初步的了解，从而为筛选适用于吸热型碳氢燃料催化裂解的催化剂提供了有力的依据。     

基团转移聚合的动力学研究

<正> 作为一种新的极性单体加聚方式的基团转移聚合(Group Transfer Polymerization,GTP),近年来发展很快。对不同引发体系和单体的基团转移聚合进行动力学研究,由此得到规律性的认识,明确聚合过程的影响因素,有利于聚合机理的完善。文献已报道了用     

Synthesis of Tigogenyl 2-Deoxy-2-phthalimido-D-glucopyranoside Derivatives and Study of their 1H-NMR Spectrum

Two protected tigogenyl glycosides were synthesized via parallel synthesis of oligosaccharide. Using chemical synthesis and conformational analysis the reason of the proton signal of 2“ acetyl group shifted up field in ^1H-NMR was discussed.     

含金纳米粒子链相关性探讨及其热稳定性的分子模拟

采用分子模拟法, 以金核外层吸附了不对称硫醚链的含金纳米粒子为研究对象, 以次序参数为依据, 对不同条件下的硫醚链及苯环间的相关性进行了探讨, 确定了较为合理的相关性判据.以此判据为依据, 并通过金核的径向分布函数的分析, 考察了纳米粒子的结构随温度变化的情况, 得出了含金纳米粒子的热稳定性较高的结论.