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   639441篇
  免费   8989篇
  国内免费   2023篇
化学   347495篇
晶体学   9088篇
力学   27461篇
综合类   14篇
数学   79220篇
物理学   187175篇
  2021年   5165篇
  2020年   5855篇
  2019年   6409篇
  2018年   8189篇
  2017年   7857篇
  2016年   12409篇
  2015年   8421篇
  2014年   12185篇
  2013年   30223篇
  2012年   23593篇
  2011年   28601篇
  2010年   19396篇
  2009年   18902篇
  2008年   25703篇
  2007年   25739篇
  2006年   23704篇
  2005年   21617篇
  2004年   19694篇
  2003年   17361篇
  2002年   16967篇
  2001年   18159篇
  2000年   13889篇
  1999年   11015篇
  1998年   9181篇
  1997年   8934篇
  1996年   8715篇
  1995年   7822篇
  1994年   7668篇
  1993年   7553篇
  1992年   8341篇
  1991年   8382篇
  1990年   8020篇
  1989年   7855篇
  1988年   7891篇
  1987年   7677篇
  1986年   7275篇
  1985年   9690篇
  1984年   9951篇
  1983年   8033篇
  1982年   8472篇
  1981年   8296篇
  1980年   7811篇
  1979年   8209篇
  1978年   8555篇
  1977年   8276篇
  1976年   8427篇
  1975年   7667篇
  1974年   7779篇
  1973年   7998篇
  1972年   5389篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.

The main theoretical aspects of detonation decomposition of powerful mixed explosives with a negative oxygen balance accompanied by the formation of nanodiamonds (ultrafine-dispersed diamonds, UDDs) are described. The basic UDD synthesis parameters are considered, and the expediency of using trotyl-hexogen alloys is shown. The conditions of diamond phase conservation in the detonation products are specified. Various versions of industrial detonation synthesis of UDDs are considered. The most efficient technology of chemical cleaning of UDDs (with nitric acid at high temperatures and pressures) for producing UDDs with the highest purity is described.

  相似文献   
992.
The terahertz absorption spectra of plasmon modes in a grid-gated double-quantum-well field-effect transistor structure is analyzed theoretically and numerically using the scattering matrix approach and is shown to faithfully reproduce strong resonant features of recent experimental observations of terahertz photo-conductivity in such a structure.  相似文献   
993.
994.
An analytical expression for the concentration profile of a low-soluble diffusant in a sample is derived for a high-capacity diffusion source. The model is checked by determining the diffusion coefficient of yttrium in beryllium.  相似文献   
995.
The motion of the front of crystallization and the growth of a film at the surface of a plate are analyzed in the case of a laminar and in the case of a turbulent flow mode. Conditions are determined under which there occurs a transition from a matt inhomogeneous structure to a transparent homogeneous structure of ice. It is shown that, for a film to be steadily preserved at the plate surface, the film thickness must be larger than a critical equilibrium-thickness value h b.c, in which case a transparent homogeneous structure of ice is formed. Otherwise, the film at the plate surface is unstable and disappears in the course of time. The icing of aircrafts is the most important application of the results obtained in this study.  相似文献   
996.
Technical Physics - An analytical expression for the generatrix of the shape of a nonlinearly vibrating charged drop of a perfect incompressible conducting fluid immersed in an ideal incompressible...  相似文献   
997.
A theory of a planar disk-shaped RF plasma source under anomalous skin effect conditions is developed. In the absence of an external magnetic field, such conditions are satisfied for transverse electromagnetic waves with phase velocities below the electron thermal velocity, and, in the presence of this field, they are satisfied for electron cyclotron waves with frequencies corresponding to the resonant absorption line. For each of these cases, the RF field power deposited in a plasma with given parameters is determined and the equivalent plasma resistance is calculated.  相似文献   
998.
The mass spectrum of a coupled state is analytically determined. The mechanism of production of a constituent mass of particles forming a coupled state is explained. The change of the coupled state and constituent particle component masses attendant to changes of the coupling constant is analyzed. The mass spectrum of a two-gluon glueball is determined with allowance for spin-orbital and spin-spin interactions.__________Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 12, pp. 33–41, December, 2004.  相似文献   
999.
1000.
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