首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   144篇
  免费   3篇
化学   100篇
力学   1篇
数学   2篇
物理学   44篇
  2022年   1篇
  2021年   5篇
  2019年   1篇
  2017年   2篇
  2015年   1篇
  2014年   2篇
  2013年   3篇
  2012年   1篇
  2011年   3篇
  2009年   4篇
  2008年   3篇
  2007年   4篇
  2006年   2篇
  2005年   5篇
  2004年   4篇
  2003年   9篇
  2002年   7篇
  2001年   2篇
  2000年   2篇
  1999年   5篇
  1998年   2篇
  1996年   3篇
  1994年   9篇
  1993年   4篇
  1992年   9篇
  1991年   6篇
  1990年   4篇
  1989年   3篇
  1988年   1篇
  1987年   4篇
  1986年   6篇
  1985年   6篇
  1984年   4篇
  1983年   3篇
  1982年   1篇
  1981年   3篇
  1980年   2篇
  1979年   3篇
  1978年   2篇
  1977年   1篇
  1973年   3篇
  1883年   2篇
排序方式: 共有147条查询结果,搜索用时 15 毫秒
71.
Synthesis of novel pyrazolopyrrolopyrazines is herein described with the aim to reach new specific PDE‐5 inhibitors of potential clinical interest in male erectile dysfunction.  相似文献   
72.
A one-pot synthesis of 2-dialkylamino-5,11-dimethyl-6H-pyrimido[5,4-b]carbazol-4(3H)-ones, as new ellipticine analogs, starting from aminocarbazole derivatives is reported. This method allowed us to prepare a library of potentially useful compounds in the pharmaceutical field.  相似文献   
73.
A facile synthetic route to the new thiazol-5-ylboronic acid pinacol ester was described herein. Its reactivity toward Suzuki cross-coupling reaction was studied to provide various 5-arylthiazoles. A comparative study between Suzuki cross-coupling reactions and palladium-catalyzed C5–H direct arylation on thiazole ring was achieved.  相似文献   
74.
2,3-dihydro[1,5] benzothiazepines and diazepines can be prepared by condensation of o-aminothiophenol or o-phenylenediamines with a variety of 3-chlorothieno-or benzothienopropanones.  相似文献   
75.
Structural analysis of minor components in mixtures is a vital requirement in the development of any pharmaceutical compound. Mass spectrometry is uniquely able to give this kind of information on the trace amounts of material present as minor impurities in a drug substance. In this study we show that a combination of mass spectrometric analysers with different characteristics is an even more powerful approach with a higher chance of establishing a potential structure. In particular the advent of analysers capable of accurate mass measurement on small amounts of material has enabled structures to be proposed in situations where previously no real conclusions could be made. Copyright 1999 John Wiley & Sons, Ltd.  相似文献   
76.
77.
In this paper the exact solution of the non-symmetric matrixRiccati equation with analytic coefficients is approximatedby a rational matrix function with a prefixed accuracy. Thisrational matrix function is locally defined as the exact solutionof a Riccati problem with matrix polynomial coefficients obtainedby truncation of the Taylor expansions of the matrix coefficientsof the original problem.  相似文献   
78.
Several new β-lactams have been synthesized in good yields, via the cyclization of 3-chloro-N-arylpropionamides in a mixture of N, N-dimethylformamide and anhydrous sodium carbonate under a nitrogen atmosphere.  相似文献   
79.
G. Lancelot 《Molecular physics》2013,111(4):1099-1108
We compute the radiative phosphorescence lifetime of caffeine using CNDO/S wavefunctions. The importance of nπ*, πσ* and σπ* singlet and triplet states is considered. The calculated values are in good agreement with experimental determinations. The role played by two-electron terms is briefly discussed.  相似文献   
80.
Russian Journal of Applied Chemistry - The effect of quinoline on the hydrodesulfurization and hydrogenation activities of bi- and trimetallic NiMo(W)/Al2O3 hydrotreating catalysts obtained using...  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号