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   634篇
  免费   1篇
化学   311篇
晶体学   2篇
力学   22篇
数学   45篇
物理学   255篇
  2022年   5篇
  2021年   5篇
  2019年   10篇
  2018年   16篇
  2017年   18篇
  2016年   18篇
  2015年   5篇
  2014年   10篇
  2013年   14篇
  2012年   11篇
  2011年   22篇
  2010年   20篇
  2009年   23篇
  2008年   22篇
  2007年   21篇
  2006年   23篇
  2005年   15篇
  2004年   12篇
  2003年   14篇
  2002年   14篇
  2001年   9篇
  2000年   17篇
  1999年   6篇
  1998年   9篇
  1997年   5篇
  1996年   8篇
  1995年   14篇
  1993年   6篇
  1992年   14篇
  1991年   13篇
  1990年   21篇
  1989年   8篇
  1988年   6篇
  1987年   10篇
  1986年   10篇
  1985年   14篇
  1984年   8篇
  1983年   7篇
  1981年   5篇
  1979年   11篇
  1978年   15篇
  1977年   12篇
  1976年   11篇
  1975年   16篇
  1974年   17篇
  1973年   11篇
  1972年   13篇
  1970年   7篇
  1969年   5篇
  1968年   4篇
排序方式: 共有635条查询结果,搜索用时 15 毫秒
1.
Russian Journal of Organic Chemistry -  相似文献   
2.
In the present paper, the probability of creating pairs of scalar particles in an arbitrary plane electromagnetic wave field is calculated. The amplitude of elastic photon scattering in the field of an arbitrary plane electromagnetic wave is calculated by the method of dispersion relations. Special cases of the plane electromagnetic wave field are examined.  相似文献   
3.
Photodestruction and adsorption of dyes in aqueous suspensions of nanopowders of titanium dioxide of anatase modification was studied. The photocatalytic activity of titanium dioxide nanopowders was examined in relation to the dispersity of particles and pH of the medium.  相似文献   
4.
5.
6.
N,N'-Bis(vinyloxyalkyl)oxamides and N,N'-bis(vinyloxyalkyl)phthalamides were synthesized in 60-95% yield by reactions of vinyloxyalkylamines with diethyl oxalate and phthalimide, respectively.  相似文献   
7.
N-[2(3)-Hydroxyalkylj-4-thiazolidinones have been synthesized by the reaction of 2(3)-vinyloxyalkylamines with mercaptoacetic acid in 24–69 % yield. The structure of the compounds obtained was supported by (R and1H NMR spectroscopic data.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 677–679, March, 1996.  相似文献   
8.
A new way of generating cyclopropyl radicals in the base-catalyzed decomposition of N-cyclopropyl-N-nitrosourea in the presence of organic reducing agents (1-phenylpyrazolidin-3-one and 4-methoxyphenol) was developed. The cyclopropyl radical generated under these conditions can not only abstract a proton from the substrate to give cyclopropane but also form C-C or C-Br bonds in reactions with aromatic substrates or polybromomethanes. Dedicated to Academician O. M. Nefedov on the occasion of his 75th birthday. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 1934–1938, November, 2006.  相似文献   
9.
For polyparaxylylene-CdS nanocomposite films prepared by solid-phase cryochemical synthesis, the dependences of the optical absorption spectra, photoluminescence intensity, and surface topography on the CdS concentration were examined. It was revealed that the most significant changes, such as the shift of the position of the exciton absorption band by ~1 eV and the increase of the surface roughness (the magnitude of variation of heights h max ? h min along a surface profile) occur within a CdS concentration range of from ~5 to ~8 vol %. The average size of the nanoparticles was determined from the position of the exciton absorption maximum: 2R np ? ? 3 nm at c ≤ 5 vol % and 2R np ≥ 5?7 nm at c ≥ 10 vol %. The formation of 3-nm particles at low CdS concentrations was confirmed by the existence of exciton photoluminescence with maximum at 370 nm. Exciton luminescence was not observed at c ≥ 10 vol %. By contrast, at all c values, photoluminescence with maxima at ~520 and ~570 nm, which is usually assigned to interstitial S and Cd atoms, correspondingly, and a the weak emission of unknown nature with a maximum at 545 nm were observed.  相似文献   
10.
We have carried out nonempirical calculations of the potential surface for isomeric rearrangements of the molecules N2O, N2S, PNO, PNS, P2O, and P2S. It was found that for the molecules N2O and N2S a linear structure is considerably more favorable than a cyclic one, which lies 60 kcal·mole–1 higher and has low stability. For P2O and P2S the linear and cyclic isomers have similar energies. For PNO and PNS there are two linear isomers and one cyclic isomer. The isomers are separated by appreciable barriers and can exist independently. It is predicted for the ABC molecules with 16 valence electrons that if two or all three of the atoms belong to the third or a later period, then the cyclic isomers should be favored to at least the same extent as the linear isomers.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 4, pp. 794–802, April, 1990.  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