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排序方式: 共有632条查询结果,搜索用时 15 毫秒
31.
Guang Xing WANG Jing Xin ZHANG Shu Feng CHEN Xiao Tian LIANG* Institute of Materia Medica Chinese Academy of Medical Sciences Peking Union Medical College Beijing 《中国化学快报》2001,(3)
Chrysotricine 1 was isolated from the Chinese herb medicine Hedyotis Chrysotricha and was shown to possess antitumor activity1. Its structure has been elucidated as a novel zwitterionic (-carboline alkaloid containing a 2,2,5-trisubstituted tetrahydrofuranyl group. The (-carboline compounds have attracted considerable attraction in recent years because of their promising and intriguing biological activities2. Recently, we have established the absolute configuration of chrysotricine by the fir… 相似文献
32.
Li Jun HE Qing Song CAI Shi Jun SHAO Sheng Xiang JIANG* Lanzhou Institute of Chemical Physics Chinese Academy of sciences Lanzhou 《中国化学快报》2001,(6)
Calixpyrroles, as new macrocyclic receptors, have gain increasing interest in host-guest chemistry. Pioneering work in this area by Sessler and co-workers have evidenced that calix[4]pyrroles are effective anion binding agents and have used for anion binding, sensing and new anion separation technologies1, 2. In this letter, we report that calix[4]pyrroles A, B and C3,4 (Scheme 1) can serve as additives in CZE for the separa- tion of halide ions. Scheme 1 A B C When analyzing anions with… 相似文献
33.
Neng Dong WANG Liu Min CHEN Sheng JIN= Xiu ZHANG Jia Hua CHEN* The Key Lab of Bioorganic Chemistry Molecular Engineering Ministry of Education China College of Chemistry Molecular Engineering Peking University Beijing 《中国化学快报》2001,(10)
The drug overdose and addiction is a serious international problem. Therefore developing a rapid, accurate, convenient and cheap method for detecting morphine in urea is useful and necessary, especially for investigation of epidemiology, identification of medical jurisprudence and determination of drug addict etc. There are many compounds that are similar to morphine in chemical structure and tend to have cross-reaction with the anti-morphine antibody. In order to reduce the cross reaction a… 相似文献
34.
Jing Chao DONG Run Tao LI* Tie Ming CHENG* Department of Bioorganic Chemistry School of Pharmaceutical Sciences Peking University Beijing 《中国化学快报》2001,(12)
Since Daly reported the structure of epibatidine and its potent analgesic activity in 19921, study on the synthesis of epibatidine and its derivatives and relationships between the structure and activity of epibatidine has received much attention2. During the course of our research for the synthesis of epibatidine derivatives, N-boc-2, 5-bis(trimethylsilyl)pyrrolidine 4 was used as the key intermediate to construct the skeleton of epibatidine via the 1, 3-dipolar cycloaddition (Scheme 1). Ac… 相似文献
35.
Qing Yan CHENG Wei LI Ying ZHOU Ming Hui ZHANG Nai Jia GUAN Ke Yi TAO* Department of Material Chemistry Nankai University Tianjin 《中国化学快报》2001,(12)
The various distillation of petroleum contains arenes. For environmental protection, the hydrogenation of arenes becomes important. The amorphous alloy is a new class of material with special catalytic properties for reduction arenes1-4. In this paper, we prepared the Ni-B/TiO2 and Ni-B/Al2O3 amorphous catalysts by impregnation and reduction by KBH4 solution. Their catalytic activities for hydrogenation arenes were tested by the hydrogenation of 1,3,5-trimethylbenzene (TMB) in the co… 相似文献
36.
采用吸附法制备了组合型Pt3Sn/Al2O3双金属催化剂, 将该催化剂用于芳香硝基化合物原位液相加氢一锅法合成N-烷基芳胺. 研究表明, 在503 K, 空速为7.5 h-1, 水体积分数为5%时, 1%(质量分数)Pt3Sn/Al2O3催化剂具有较高的催化性能, 硝基苯的转化率为100%, N-乙基苯胺和N,N-二乙基苯胺的总选择性为98.2%. 同时,该催化剂对原位液相加氢烷基化反应具有一定普适性, 本文研究的14 种芳香硝基化合物与低级脂肪醇反应,均具有较高的N-烷基化产率. 相似文献
37.
分子电子学已成为21世纪研究的热点. 通过将具有特定功能的分子连接在纳米尺度金属电极之间从而构筑包括分子导线、开关、整流器在内的各种分子尺度电子器件, 这引起了科学家们广泛的研究兴趣. 在分子电子学研究中, 构筑金属/分子/金属(MMM)分子结是研究分子器件中电子传输性质的关键. 尽管已经取得了很大的进展, 目前在纳米尺度下构筑稳定可靠的MMM分子结并测试单个分子的电学性质仍然面临很多挑战. 本文着重对单分子电学性质的测试技术和相关理论研究的最新进展以及存在的挑战做了概述. 相似文献
38.
39.
采用循环伏安法(Cyclic Voltammetry,CV)在碱性条件下电解石墨棒,得到水溶性的荧光碳量子点. 通过透射电子显微镜(TEM)、拉曼光谱(Raman spectrum)、原子力显微镜(AFM)对所制备的碳量子点进行形貌及结构表征,发现该碳量子点由1~4层石墨烯片层堆积形成,粒径在19 nm左右,厚度在1 nm左右. 通过荧光光谱(PL)、紫外可见吸收光谱(UV-vis)、傅里叶变换红外光谱(FTIR)、X射线光电子能谱(XPS)对所制备的碳量子点进行性质测定,发现该碳量子点在400和525 nm处有两个荧光发射峰,且通过控制扫描周数可以调节两个发射峰的相对强度,从而调控碳量子点的荧光颜色:随着扫描周数的增加,400 nm处发射峰的相对强度逐渐减小,而525 nm处发射峰的相对强度逐渐增大,两个荧光发射峰分别与碳量子点的π-π共轭体系和含氧官能团的n-π共轭体系有关. 相似文献
40.
Determination of Partial Molar Volumes of EPA and DHA Ethyl Esters in Supercritical Carbon Dioxide 总被引:4,自引:0,他引:4
Mei HUANG Xian Da WANG Ren Tian XIONG Ping Dong WU Qi Long REN* National Laboratory of Secondary Resources Chemical Engineering Zhejiang University Hangzhou 《中国化学快报》2002,13(1)
The use of supercritical fluids (SCFs) as solvents has been attracting widespread interest in the research and commercial applications. The study of partial molar volumes of solutes at infinite dilution in the near-critical region is of considerable fundamental importance, as these data reflects the interactions occurring between the solute and the solvent. Experimental measurements of partial molar volumes may be divided into two categories: direct and indirect methods. The direct methods… 相似文献