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   147篇
  免费   7篇
化学   106篇
数学   12篇
物理学   36篇
  2023年   2篇
  2022年   2篇
  2021年   2篇
  2020年   1篇
  2019年   1篇
  2018年   2篇
  2016年   3篇
  2015年   7篇
  2014年   2篇
  2013年   9篇
  2012年   13篇
  2011年   11篇
  2010年   6篇
  2009年   5篇
  2008年   15篇
  2007年   6篇
  2006年   7篇
  2005年   9篇
  2004年   6篇
  2003年   12篇
  2002年   5篇
  2000年   1篇
  1999年   1篇
  1997年   1篇
  1996年   2篇
  1994年   1篇
  1993年   1篇
  1992年   1篇
  1988年   3篇
  1987年   1篇
  1986年   2篇
  1985年   4篇
  1980年   2篇
  1979年   2篇
  1978年   4篇
  1976年   1篇
  1972年   1篇
排序方式: 共有154条查询结果,搜索用时 15 毫秒
41.
A new, highly flexible porphyrin dimer was isolated in preparative scale from a dynamic disulfide library; this receptor adjusts to fit guests with a wide range of steric requirements and, whilst C60 proved to be an unsuitable template for this library, a new C60-porphyrin complex was isolated and characterised.  相似文献   
42.
43.
New macrocycles incorporating a porphyrin and a [small pi] electron-rich aromatic were prepared from a dynamic disulfide library. The outcome could be influenced by use of templates.  相似文献   
44.
A membranous closed surface is introduced to confine colored vector gluon fields in a Lorentz invariant manner. Since the colored pointlike quarks are always coupled to the gluon fields, they become confined inside the closed membrane. The Hamiltonian formulation of the model is presented, and the classical string limit is discussed.  相似文献   
45.
This paper describes, for the first time, a simple and effective synthetic route for covalently bonding the chemiluminescence reagent, (4-[4-(dichloromethylsilanyl)-butyl]-4'-methyl-2,2'-bipyridyl)bis(2,2'-bipyridyl)ruthenium(II) onto silica particles. The subsequent preparation of chemically regeneratable detection cells and their preliminary analytical evaluation with both sequential injection analysis and flow injection analysis are also reported. Unoptimised analytical figures of merit were established for standard solutions of codeine and sodium oxalate with detection limits calculated from three times the standard deviation of the blank signal, of 1 x 10(-8) M and 3 x 10(-7) M respectively. The chemically immobilised reagent exhibited some intriguing solvent and kinetic effects, which are also briefly discussed.  相似文献   
46.
47.
Kieran Calvert 《代数通讯》2020,48(4):1476-1498
Abstract

In this paper, we define a new presentation for the Dunkl-Opdam subalgebra of the rational Cherednik algebra. This presentation uncovers the Dunkl-Opdam subalgebra as a Drinfeld algebra. We use this fact to define Dirac cohomology for the DO subalgebra. We also formalize generalized graded Hecke algebras and extend a Langlands classification to generalized graded Hecke algebras.  相似文献   
48.
The copper aminotropones Cu[ON(R′)C7H4R-4]2 [R = H, R′ = Me (13), Et (14), n-Pr (15), n-Bu (16), Bz (17), MenOCH2CH2 (20); R = i-Pr, R′ = Me (18), n-Pr (19), MenOCH2CH2 (21)] have been prepared from the corresponding aminotropones HN(R′)OC7H4R-4 (17) by reacting with copper(II) acetate in aqueous ethanol. 20, 21 contain the flavourant, menthol, as part of the ligand. The structures of 5 (R = H, R′ = Bz), a hydrogen-bonded dimer, 14 and 20, both incorporating square-planar, four-coordinate copper centres, have been determined by X-ray crystallography. The antibacterial activities of complexes 13, 17, 20 and 21 have been assayed against Staphylococcus waneri, an in vitro model of plaque inhibition effects, and found to be more active than a commercial toothpaste formulation, but less active than the O,O-chelated copper(II) complex of ethylmaltol.  相似文献   
49.
In phase shifting interferometry, phase errors due to harmonic components of a fringe signal can be minimized by applying synchronous phase shifting algorithms with more than four samples. However, when the phase shift calibration is inaccurate, these algorithms cannot eliminate the effects of a non-sinusoidal waveform. It is shown that by taking a number of samples beyond one period of the fringe pattern, phase errors due to the harmonic components of the fringe signal can be eliminated, even when there exists a constant error in the phase shift interval. A general procedure for constructing phase shifting algorithms that eliminate these errors is derived. A seven-sample phase shifting algorithm is derived as an example, in which the effect of the second harmonic component can be eliminated in the presence of a constant error in the phase shift interval.  相似文献   
50.
Tribenzyltin azide adopts a polymeric structure with 1,3‐bridging azide groups; the tin exhibits an almost regular trigonal bipyramidal trans‐N2SnC3 environment. Copyright © 2003 John Wiley & Sons, Ltd.  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