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81.
1 INTRODUCTIONItwaswellknown thatelementsofthesecondary and higherrow are in generaldifficulty to form multiplebondsin which apπ hybridized stateisinvolved〔1〕.Thus,simple compounds containing multiple phosphorus carbon bonds,such as methyl dynephosphine( HC≡P) 〔2 - 3〕 and methylenephosphine( H2 C=PH〔4〕,are notstableat room temperature.Three methods to stabilize compounds containing double ormultiple bond involving phosphorusatom in the pπ hybridized state are often used.The f… 相似文献
82.
Si WANG Pei Cheng ZHANG Ruo Yun CHEN De Quan YU* Institute of Materia Medica Chinese Academy of Medical Sciences 《中国化学快报》2001,(9)
Goniothalamus cheliensis Hu (Annonaceace) is a small tree or shrub in Yunnan Province, southwest of China. Acetogenins, styryllactones and alkaloids1-3 from the genus were reported in the previous literature and many of them showed strong cytotoxic activities against a number of human cancer cell lines4. The titled plant has been the subject of our investigation due to the impressive cytotoxicity of its organic extract against mouse lymphocytic leukemia cells in preliminary pharmacological s… 相似文献
83.
Hong Ping LI Hai Fei ZHANG Jun LIU Bu Xing HAN* Center for Molecular Sciences Institute of Chemistry Chinese Academy of Sciences Beijing 《中国化学快报》2001,(4)
There are some unique advantages for chemical reactions in SCFs. For example, reaction rates, yields, and selectivity can be tuned by pressure or small amount of cosolvent. SCFs can be used to replace environmentally undesirable solvents. It is not surprised that in recent years the use of SCFs as solvents for chemical reaction media has received much attention. However, mechanism for the effect of pressure and cosolvents on chemical reactions is not very clear. Tautomeric reactions are id… 相似文献
84.
85.
合成了三种新型含噻吩环大环Schiff碱及其中一种与镧,钍的配合物。它们的结构均经IR,HNMR和元素分析表征。 相似文献
86.
Mei Zhong JIN Li YANG Long Ming WU You Chen LIU Zhong Li LIU* National Laboratory of Applied Organic Chemistry Lanzhou University Lanzhou 《中国化学快报》2001,(4)
Reduction of C=N double bonds has been recognized as an important reaction both in organic chemistry and bio-chemistry1. Hantzsch 1,4-dihydropyridine (HEH, one of NADH model compounds) has been reported as a reductive reagent for imines2. However, application of dihydropyridines as practical reducing reagents in organic synthesis is limited because of their instability3. Like NADH models, 2-phenyl-N, N-dimethylbenzimidazoline (PDMBI) is an efficient electron and hydrogen donor (Eox = 0… 相似文献
87.
介绍了带LN2预冷的二级膨胀循环的流程计算方法,并提出了优化计算的思路和计算机程序实现的方法;最后就换热器热端温差对制冷机效率的影响进行了讨论 相似文献
88.
Zhi Hui Zhou Jian Hua Yang* Li Feng Chang Yan Zhang Wei Guo Sun Jin Qu Wang* State Key Laboratory of Fine Chemicals Institute of Adsorption Inorganic Membrane Dalian University of Technology Dalian PR China 《中国化学快报》2007,18(4):455-457
Novel NaA/carbon nanocomposite thin films were successfully prepared on a porous a-Al2O3 substrate by incorporatingnanosized NaA zeolite into novolak-type phenolic resin.The prepared films were characterized by XRD,SEM and single gaspermeation tests.The NaA zeolite/carbon nanocomposite thin films exhibited that the ideal separation factor of CO2/CH4 was 28.4and the carbon dioxide flux was 3.39*10-7mol/(Pa m2s)at room temperature and under a pressure difference of 100 kPa,whichwas two orders of magnitude higher than that of pure carbon membrane prepared at the same procedures and conditions as those ofcomposite films.From the SEM images,the films were continuous and highly intergrown.Compared with carbon membranes,thethickness of nanocomposite films was drastically decreased,which was helpful to reduce the diffusion resistance and increase theflux of gas permeance. 相似文献
89.
90.
Cui Hua XUE Qi Ming MU Shu Hua CHEN* The Faculty of chemistry Sichuan University Chengdu 《中国化学快报》2001,(5)
Molecular tweezers is a novel type of artificial receptors, which not only offer the advantage of efficient construction but also their surfaces can be tailored for specific applications. The clefts of molecular tweezers are particularly effective in regard to complementarity with substrates since functional groups attached to the interior of the cleft converge on substrates held inside1. So, in recent years, the molecular tweezers receptors have attracted more and more attention in molecular … 相似文献