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   453675篇
  免费   3384篇
  国内免费   876篇
化学   216551篇
晶体学   5742篇
力学   24396篇
综合类   7篇
数学   61461篇
物理学   149778篇
  2021年   4060篇
  2020年   4535篇
  2019年   5390篇
  2018年   7689篇
  2017年   7818篇
  2016年   10267篇
  2015年   5214篇
  2014年   9350篇
  2013年   19251篇
  2012年   15571篇
  2011年   18459篇
  2010年   14337篇
  2009年   14423篇
  2008年   17421篇
  2007年   17416篇
  2006年   16001篇
  2005年   14096篇
  2004年   13430篇
  2003年   12191篇
  2002年   12326篇
  2001年   12814篇
  2000年   10055篇
  1999年   7569篇
  1998年   6719篇
  1997年   6480篇
  1996年   5631篇
  1995年   5374篇
  1994年   5307篇
  1993年   5182篇
  1992年   5539篇
  1991年   5863篇
  1990年   5780篇
  1989年   5568篇
  1988年   5461篇
  1987年   5518篇
  1986年   5076篇
  1985年   6242篇
  1984年   6679篇
  1983年   5586篇
  1982年   5995篇
  1981年   5663篇
  1980年   5324篇
  1979年   5860篇
  1978年   6048篇
  1977年   6165篇
  1976年   6313篇
  1975年   5832篇
  1974年   5677篇
  1973年   5966篇
  1972年   4543篇
排序方式: 共有10000条查询结果,搜索用时 314 毫秒
991.
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   
992.
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   
993.
A semiempirical model is proposed for the calculation of electrical, magnetic and thermal parameters of the plasma of a high-frequency induction discharge. The model is based on solving a system of two-dimensional Maxwell equations written for a cylindrical coordinate system.  相似文献   
994.
A method of teaching of one of the divisions of electrodynamics devoted to relativity theory is suggested. The presentation is based on the four-dimensional formalism, which allows a number of fundamental physical phenomena to be considered from a unified position. The content is in full conformity with the approved standard programs for students and postgraduates of radio physical and radio technical specialities of universities. The methods can be useful to the teachers, scientific workers, and engineers concerned with other directions and specialities.  相似文献   
995.
Based on particular solutions of a system of wave equations which describe electromagnetic processes in an unbounded biisotropic medium and are represented in the form of generalized power series, a dispersion equation is obtained for a two-layer circular waveguide with a chiral and a dielectric layer. The solution of the dispersion equation is analyzed for some types of natural waves.  相似文献   
996.
A possibility of application of semiconductor lasers of the visible range as exciting sources for Raman spectroscopy is studied. An experimental set-up for measuring Raman spectra of polycrystalline dielectrics and broad-gap semiconductors excited by a semiconductor laser with a wavelength of 640 nm was created. The conditions under which the spectral width of the lasing line of a semiconductor laser was within 10-3 cm-1 in the continuous mode with a power of 10 mW are realized. The characteristics of various types of exciting sources used in Raman spectroscopy are compared. The results of studies of the characteristic Raman spectra excited with a semiconductor laser in polycrystalline sulfur are presented.  相似文献   
997.
998.
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