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   274671篇
  免费   2510篇
  国内免费   656篇
化学   146436篇
晶体学   4266篇
力学   12153篇
综合类   9篇
数学   30458篇
物理学   84515篇
  2019年   2368篇
  2018年   3149篇
  2017年   3155篇
  2016年   4566篇
  2015年   2744篇
  2014年   4400篇
  2013年   11022篇
  2012年   8347篇
  2011年   10225篇
  2010年   7255篇
  2009年   7073篇
  2008年   9641篇
  2007年   9836篇
  2006年   9216篇
  2005年   8375篇
  2004年   7684篇
  2003年   6970篇
  2002年   6904篇
  2001年   7476篇
  2000年   5837篇
  1999年   4440篇
  1998年   3938篇
  1997年   3929篇
  1996年   3698篇
  1995年   3426篇
  1994年   3629篇
  1993年   3346篇
  1992年   3810篇
  1991年   3771篇
  1990年   3699篇
  1989年   3568篇
  1988年   3649篇
  1987年   3567篇
  1986年   3382篇
  1985年   4514篇
  1984年   4752篇
  1983年   3945篇
  1982年   4108篇
  1981年   4032篇
  1980年   4015篇
  1979年   3985篇
  1978年   4292篇
  1977年   4194篇
  1976年   4278篇
  1975年   3933篇
  1974年   4002篇
  1973年   4145篇
  1972年   2897篇
  1971年   2432篇
  1970年   2220篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
161.
Publication list     
The helium atom in its ground state, subject to strong magnetic fields, is treated using a variational method. Trial functions consisting of Gaussians with nonlinear parameters variationally optimized are used. The form of these functions is a generalized s-symmetry-state properly modified to admit spatial deformation along the direction on which the magnetic field is applied. © 1994 John Wiley & Sons, Inc.  相似文献   
162.
163.
164.
165.
The capability of gated saturable absorbers for single-pulse selection is studied theoretically using the classical space-time-dependent rate-equation model. The dynamics of operation is followed experimentally by the well-known pump—probe technique. Comparing the theoretical and experimental results, it is found that gated saturable absorbers can efficiently be used for pulse forming and pulse selection of pulses longer than picosecond.  相似文献   
166.
GIPKh catalysts     
In the Russian Scientific Center Applied Chemistry catalysts have been developed for the gas-phase fluorination of organics, including chlorine-containing substances, hydrogenation and reductive amination of organic substances, decomposition of liquid substances to gases, complete oxidation and reduction, suitable for environment at protection.  相似文献   
167.
We present the results of an experimental investigation of a RF splitting of57Fe hyperfine lines in the regime of NMR and Mössbauer double resonance. The experiments have been performed as a function of RF field intensity and static magnetic field magnitude. The intensity of the RF components and the separation between them are extremely sensitive to the frequency and amplitude of the RF magnetic field. The RF splitting of hyperfine lines is inversely proportional to the strength of the static magnetic field.  相似文献   
168.
The electrical conductivity of hydrosols of ultradispersed diamonds was studied. The electromembrane method for cleaning and concentrating of ultradispersed diamonds in hydrosols was considered. The influence exerted by the concentration of the dispersed phase on the electrical characteristics of the cleaning process was analyzed. A mathematical relation making it possible to evaluate the output characteristics of the process and to determine the geometrical characteristics of the apparatus was proposed.  相似文献   
169.
The radiation emitted by charged, scalar particles in a Schwarzschild field with maximal acceleration corrections is calculated classically and in the tree approximation of quantum field theory. In both instances the particles emit radiation that has characteristics similar to those of gamma-ray bursters.  相似文献   
170.
This paper reports on the first experimental observation of quantum-well states and sp-type resonances in thin single-crystal gold, silver, and copper layers formed on single-crystal W(110) surfaces, which result from spatial localization of Bloch-type electronic wave functions in a quantum well with potential barriers at the vacuum/metal and metal/W(110) interfaces. The quantization of the valence-band electronic structure in Au/W(110), Ag/W(110), and Cu/W(110) systems was studied experimentally using angle-resolved photoelectron spectroscopy.  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