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   303篇
  免费   13篇
化学   303篇
晶体学   12篇
物理学   1篇
  2024年   1篇
  2023年   1篇
  2021年   4篇
  2020年   7篇
  2019年   2篇
  2018年   2篇
  2017年   2篇
  2016年   7篇
  2015年   14篇
  2014年   13篇
  2013年   25篇
  2012年   21篇
  2011年   4篇
  2010年   16篇
  2009年   20篇
  2008年   19篇
  2007年   19篇
  2006年   20篇
  2005年   11篇
  2004年   5篇
  2003年   9篇
  2002年   16篇
  2001年   13篇
  2000年   17篇
  1999年   13篇
  1998年   4篇
  1997年   5篇
  1996年   6篇
  1995年   3篇
  1994年   4篇
  1993年   5篇
  1992年   1篇
  1991年   4篇
  1990年   2篇
  1985年   1篇
排序方式: 共有316条查询结果,搜索用时 46 毫秒
21.
22.
New cluster complexes [W3S4(Acac)3(PPh3)3]PF6 · 0.5CHCl3 (Acac = CH3C(O)CHC(O)CH3) (I) and [W3S4(Hfac)3(PPh3)2Br] · 2CHCl3 (Hfac = CF3C(O)CHC(O)CF3) (II) were synthesized. Their molecular and crystal structures were determined by X-ray diffraction. The cis-cis type of coordination of acetylacetonate and hexafluoroacetylacetonate ligands in I and II, respectively, was established, and the PPh3 ligands were found in the trans-positions with respect to the “capping” sulfide ligand (μ3-S).  相似文献   
23.
The synthesis and single-crystal X-ray diffraction study of Cs[UO2(SeO4)(OH)] · 1.5H2O (I) and Cs[UO2(SeO4)(OH)] · H2O (II) are performed. Compound I crystallizes in the monoclinic crystal system, a = 7.2142(2) Å, b = 14.4942(4) Å, c = 8.9270(3) Å, β = 112.706(1)°, space group P21/m, Z = 4, and R = 0.0222. Compound II is monoclinic, a = 8.4549(2) Å, b = 11.5358(3) Å, c = 9.5565(2) Å, β = 113.273(1)°, space group P21/c, Z = 4, and R = 0.0219. The main structural units of crystals I and II are [UO2(SeO4)(OH)]? layers which belong to the AT 3 M 2 crystal chemical group of uranyl complexes (A = UO 2 2+ , T 3 = SeO4 2?, and M 2 = OH?). In structure I, johannite-like layers are found. Structure II is a topological isomer of I. The two structures differ in the number of U(VI) atoms bound to the central atom by all bridging ligands.  相似文献   
24.
25.
26.
27.
1,2,4-Triazole derivative substituted in the 4th position — 4-(3,4-dichlorphenyl)-1,2,4-tirazole — has been synthesized. Crystal and molecular structure of the compound were determined by single crystal X-ray diffraction. Molecular geometry optimization and effective charge calculations were performed by DFT methods.  相似文献   
28.
29.
Although the cyclo‐P6 complex [(Cp*Mo)2(μ,η66‐P6)] ( 1 ) was reported 30 years ago, little is known about its chemistry. Herein, we report a high‐yielding synthesis of 1 , the complex 2 , which contains an unprecedented cyclo‐P10 ligand, and the reactivity of 1 towards the “naked” cations Cu+, Ag+, and Tl+. Besides the formation of the single oxidation products 3 a,b which have a bisallylic distorted cyclo‐P6 middle deck, the [M( 1 )2]+ complexes are described which show distorted square‐planar (M=Cu( 4 a ), Ag( 4 b )) or distorted tetrahedral coordinated (M=Cu( 5 )) M+ cations. The choice of solvent enabled control over the reaction outcome for Cu+, as proved by powder XRD and supported by DFT calculations. The reaction with Tl+ affords a layered two‐dimensional coordination network in the solid state.  相似文献   
30.
A ribbed-monofunctionalized macrobicyclic iron(II) complex with tert-butyl sulfide substituents has been prepared via nucleophilic substitution of its dichloroclathrochelate precursor with tert-butylthiolate ion. This new complex has been characterized using elemental analysis, IR and multinuclear NMR spectroscopy, and the single crystal X-ray diffraction. Its thermal destruction occurs with release of isobutylene and polyunsaturated hydrocarbons giving iron borate, iron fluoropolyborate, and iron nitride as follows from combined thermal analysis and X-ray powder diffraction data.  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