正丁基锂四氢呋喃引发α-甲基苯乙烯阴离子平衡聚合动力学及反应机理研究

本文研究了以正丁基锂为引发剂,四氢呋喃为添加剂,环己烷为溶剂中的α-甲基苯乙烯阴离子平衡聚合动力学。讨论了体系中的反应活性种;提出了聚合机理;得到了聚合温度为20℃时的平衡单体浓度与活性种速率常数及添加剂浓度之间的关系式。     

圆二色谱中的激子手性法在有机化学中的应用

激子手性法是圆二色谱领域内,近一、二十年内发展的一种测定有机化合物绝对构型的可靠方法。本文对其基本原理及规律作一简要介绍。并以邻二醇、共轭烯酮,共轭二烯及丙烯醇为例,介绍本法在测定绝对构型中的应用。此外,本法也可用于糖类的结构研究。     

稀土高氯酸溶液导数光谱的研究及其在分析中的应用 Ⅶ.四阶导数分光光度法直接测定混合稀土氧化物中镱和镝

本文在近红外光区研究了镱(Ⅲ)和镝(Ⅲ)1mol/L HClO_4溶液的四阶导数吸收光谱,认真选择了仪器操作条件,提高了测定镱和镝的选择性。通过校正系数法,使镱的光度法测定成为可能,克服了在可见光区测定镝需要校正干扰的缺点,达到在混合稀土中直接测定镱和镝的目的。     

三硝基苯磺酸离子选择电极的制备和应用

三硝基苯磺酸是氨基酸分析常用试剂,在水溶液中它是稳定的一价阴离子。Sarantonis曾研制液膜型三硝基苯磺酸离子选择电极,间接测定氨基酸的浓度,其电极的线性响应范围为1.1×10~(-1)～5.1×10~(-5)mol·L~(-1)。     

红厚壳属植物化学成份及药理活性研究进展

综述了近年来对红厚壳属植物中的化学成分及药理活性研究，重点讨论了18种 红厚壳属植物中Zhao吨酮类，香豆素类，黄酮类和萜类的化学成分，并讨论了它们 的药理活性。     

In-channel indirect amperometric detection of nonelectroactive anions for electrophoresis on a poly(dimethylsiloxane) microchip

In the present paper, we describe a microfluidics-based sensing system for nonelectroactive anions under negative separation electric field by mounting a single carbon fiber disk working electrode (WE) in the end part of a poly(dimethylsiloxane) microchannel. In contrast to work in a positive separation electric field described in our previous paper (Anal. Chem. 2004, 76, 6902-6907), here the electrochemical reduction reaction at the WE is not coupled with the separation high-voltage (HV) system, whereas the electrochemical oxidation reaction at the WE is coupled with the separation HV system. The electroactive indicator is the carbon fiber WE itself but not dissolved oxygen. This provides a convenient and sensitive means for the determination of nonelectroactive anions by amperometry. The influences of separation voltage, detection potential, and the distance between the WE and the separation channel outlet on the response of the detector have been investigated. The present detection mode is successfully used to electrochemically detect F-, Cl-, SO4(2-), CH3COO-, H2PO4-. Based on the preliminary results, a detection limit of 2 microM and a dynamic range up to three orders of magnitude for Cl- could be achieved.     

线粒体热化学研究──Ⅳ．鱼类肝脏线粒体代谢的微量热学研究

线粒体热化学研究──Ⅳ．鱼类肝脏线粒体代谢的微量热学研究谭安民，刘义，谢昌礼，屈松生，顾贫，邓凤姣（武汉大学化学系武汉４３００７２）（武汉大学生命科学院武汉）关键词鱼肝脏，线粒体，微量热学，热化学线粒体在能量代谢的过程中，除一部分能量用于合成ＡＴＰ外...     

铁(Ⅲ)-邻菲啰啉体系流动注射-分光光度法测定药品中的抗坏血酸

本文基于抗坏血酸还原铁(Ⅲ)-邻菲啰啉为红色铁(Ⅱ)-邻菲啰啉,建立了流动注射分光光度法测定药品中抗坏血酸的方法。本法体系简单,操作方便、快速,标准加入试验的回收率为92～103％。     

磷钼酸铵-孔雀绿-PVA分光光度法测定钽粉中磷

提出了以磷钼酸铵-孔雀绿-PVA三元络合物体系测定金属钽粉中磷的方法,该体系表观摩尔吸光系数ε=8.19×104L.mol-1.cm-1,加标回收率为:99.3%~105%,方法的RSD为:5.9%。有效地解决了目前高纯钽粉中磷的分析难题,方法已应用于实际产品的分析中。     

Probing the local structure and mechanical response of nanostructures using force modulation and nanofabrication

Nanostructures of self-assembled monolayers (SAMs) are designed and produced using coadsorption and nanografting techniques. Because the structures of these artificially engineered domains are predesigned and well-characterized, a systematic investigation is possible to study the mechanical responses to force modulation under atomic force microscope tips. Force modulation imaging reveals characteristic contrast sensitivity to changes in molecular-level packing, molecule chain lengths, domain boundaries, and surface chemical functionalities in SAMs. By means of actively tuning the driving frequency, the resonances at the tip-surface contact are selectively activated. Therefore, specific surface features, such as the edges of the domains and nanostructures or desired chemical functionalities, can be selectively enhanced in the amplitude images. These observations provide a new and active approach in materials characterization and the study of nanotribology using atomic force microscopy.