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   601299篇
  免费   7418篇
  国内免费   1944篇
化学   317460篇
晶体学   9202篇
力学   27295篇
综合类   14篇
数学   72587篇
物理学   184103篇
  2021年   4985篇
  2020年   5534篇
  2019年   6087篇
  2018年   7774篇
  2017年   7603篇
  2016年   11656篇
  2015年   7400篇
  2014年   11450篇
  2013年   27565篇
  2012年   21057篇
  2011年   26036篇
  2010年   18303篇
  2009年   18095篇
  2008年   23766篇
  2007年   23606篇
  2006年   21987篇
  2005年   19754篇
  2004年   18289篇
  2003年   16037篇
  2002年   15977篇
  2001年   17839篇
  2000年   13550篇
  1999年   10725篇
  1998年   8973篇
  1997年   8729篇
  1996年   8350篇
  1995年   7574篇
  1994年   7464篇
  1993年   7349篇
  1992年   8034篇
  1991年   8166篇
  1990年   7782篇
  1989年   7635篇
  1988年   7674篇
  1987年   7476篇
  1986年   7047篇
  1985年   9259篇
  1984年   9581篇
  1983年   7625篇
  1982年   7855篇
  1981年   7788篇
  1980年   7314篇
  1979年   7799篇
  1978年   8038篇
  1977年   7901篇
  1976年   7886篇
  1975年   7257篇
  1974年   7253篇
  1973年   7267篇
  1972年   5168篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
981.
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   
982.
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   
983.
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   
984.
985.
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   
986.
987.
988.
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   
989.
Sensitivity-enhanced 2D IPAP experiments using the accordion principle for measuring one-bond 13C'-13Calpha and 1Halpha-13Calpha dipolar couplings in proteins are presented. The resolution of the resulting spectra is identical to that of the decoupled HSQC spectra and the sensitivity of the corresponding 1D acquisitions are only slightly lower than those obtained with 3D HNCO and 3D HN(COCA)HA pulse sequences due to an additional delay 2Delta. For cases of limited resolution in the 2D 15N-1HN HSQC spectrum the current pulse sequences can easily be modified into 3D versions by introducing a poorly digitized third dimension, if so desired. The experiments described here are a valuable addition to the suites available for determination of residual dipolar couplings in biological systems.  相似文献   
990.
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