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   285篇
  免费   3篇
化学   227篇
晶体学   3篇
力学   4篇
数学   11篇
物理学   43篇
  2023年   3篇
  2022年   3篇
  2021年   12篇
  2020年   8篇
  2019年   16篇
  2018年   20篇
  2017年   9篇
  2016年   11篇
  2015年   7篇
  2014年   11篇
  2013年   17篇
  2012年   13篇
  2011年   19篇
  2010年   11篇
  2009年   9篇
  2008年   12篇
  2007年   14篇
  2006年   7篇
  2005年   6篇
  2004年   6篇
  2003年   10篇
  2002年   4篇
  2001年   6篇
  2000年   6篇
  1997年   2篇
  1996年   2篇
  1995年   3篇
  1994年   2篇
  1990年   1篇
  1988年   2篇
  1987年   2篇
  1986年   2篇
  1985年   2篇
  1984年   2篇
  1983年   3篇
  1982年   2篇
  1979年   1篇
  1978年   4篇
  1976年   1篇
  1975年   4篇
  1974年   1篇
  1973年   3篇
  1972年   3篇
  1971年   1篇
  1970年   1篇
  1968年   1篇
  1967年   1篇
  1966年   2篇
排序方式: 共有288条查询结果,搜索用时 15 毫秒
111.
This talk presents the analyses results of the diboson (WW or WZ) resonances production search in pp collisions at √s = 8 and 13 TeV with the ATLAS detector at the LHC with the semileptonic final state. As benchmark signal models Randall-Sundrum bulk model for KK G* → WW and Heavy Vector Triplet model for W′ → WZ and Z′ → WW are used. No significant excess for diboson resonances production is observed and upper limits on the production cross section times branching fraction of G*, W′ and Z′ are determined at 95% CL.  相似文献   
112.
The spectra of p, d, and t charged particles produced in stopped-pion absorption by nuclei are analyzed. Respective measurements were performed for 17 nuclei by means of a semiconductor spectrometer. A phenomenological model developed previously for medium-heavy and heavy nuclei was applied to describing the spectra and yields of charged particles originating from light nuclei (6,7Li, 9Be, 10,11B, and 12C). The contribution of intranuclear clusters (such as pp and 3,4He) to pion absorption was estimated.  相似文献   
113.
Structural Chemistry - In an attempt to synthesize 4-thia-6-azatricyclo[5.3.1.13,9]dodecan-5-imine as putative antihypotensive agent with prolonged effect, a reaction of...  相似文献   
114.
115.
116.
Two crystal modifications (m-1 and m-2) of the mixed-ligand complex ZnPhen(i-PrOCS2)2 have been isolated. Their crystal structures were solved using X-ray diffraction data (CAD-4 diffractometer, MoK radiation, 3141 and 3532 Fhkl, R = 0.0363 and 0.0304). For both modifications, the crystals are monoclinic with unit cell parameters a = 10.543(2), b = 13.494(3), c = 16.875(3) , = 102.08(3)°, V = 2347.6(8) 3, Z = 4, space group P21/n (m-1) and a = 10.931(2), b = 12.996(3), c = 16.288(3) , = 92.69(3)°, V = 2311.3(8) 3, Z = 4, space group P21/n (m-2). The structures basically consist of discrete monomer molecules in which the Zn atom has a tetragonal pyramidal (m-1: ZnN2S3, c.n. 5, bidentate and monodentate i-PrOCS 2 - ligands) or distorted octahedral (m-2: ZnN2S4, c.n. 6, bidentate i-PrOCS 2 - ligands) environment. Molecular packings and their interactions in the structures are discussed.  相似文献   
117.
A method is described for the preparation of 1,3-diacetylferrocene, in which ethylferrocene is first acetylated with acetyl chloride in the presence of AlCl3 in methylene chloride to a mixture of isomeric acetylethylferrocenes. This mixture is then subjected to thin-layer chromatography, a mixture of the 1,1′- and 1,3-derivatives free from the 1,2-isomer being obtained. After oxidation of this mixture with MnO2 to a mixture of 1,1′- and 1,3-diacetylferrocenes, the isomers are separated by preparative thin-layer chromatography.  相似文献   
118.
New 3-bromo and 1,4-diaminomethyl derivatives of 4-aminopyrazolo[3,4-d]pyrimidine were obtained by bromination and aminomethylation, respectively. 4-Bromopyrazolo[3,4-d]pyrimidines were synthesized for the first time by diazotization of 4-aminopyrazolo[3,4-d]pyrimidines.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 982–984, July, 1982.  相似文献   
119.
The proton magnetic resonance spectra for ferrocene derivatives have been investigated in the solid state at a frequency of 27.5 MHz and at temperatures within the range 4.2–300 K. Evidence for re-orientation in various substituent groups and cyclopentadienyl rings has been deduced on the basis of the temperature dependence of the second moment of the PMR lines. The experimentally observed decrease in the second moment has been compared with the calculated contributions of different molecular groups to the second moment thus enabling an identification of these groups. In computing the second moment, account has been taken of both intra- and intermolecular dipole-dipole interactions. It is shown that the introduction of substituents into some ferrocene rings affects the magnitude of the re-orientation energy for both the substituted and unsubstituted rings. The change of the re-orientation energy of the substituted and unsubstituted rings in substituted ferrocenes with the structure and electronic properties of the substituents is discussed.  相似文献   
120.
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