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   1317012篇
  免费   29601篇
  国内免费   7735篇
化学   655186篇
晶体学   20316篇
力学   74236篇
综合类   103篇
数学   239960篇
物理学   364547篇
  2021年   13437篇
  2020年   15876篇
  2019年   16015篇
  2018年   12690篇
  2016年   27672篇
  2015年   20698篇
  2014年   30276篇
  2013年   74075篇
  2012年   36666篇
  2011年   32922篇
  2010年   36645篇
  2009年   39132篇
  2008年   32785篇
  2007年   28316篇
  2006年   34549篇
  2005年   27265篇
  2004年   28486篇
  2003年   27152篇
  2002年   28347篇
  2001年   26581篇
  2000年   23786篇
  1999年   22042篇
  1998年   20792篇
  1997年   20808篇
  1996年   21003篇
  1995年   19078篇
  1994年   18515篇
  1993年   18078篇
  1992年   17822篇
  1991年   18162篇
  1990年   17390篇
  1989年   17423篇
  1988年   17015篇
  1987年   17031篇
  1986年   15927篇
  1985年   22373篇
  1984年   23677篇
  1983年   19885篇
  1982年   21590篇
  1981年   20833篇
  1980年   20179篇
  1979年   20290篇
  1978年   21628篇
  1977年   21213篇
  1976年   20907篇
  1975年   19635篇
  1974年   19240篇
  1973年   19772篇
  1972年   14257篇
  1967年   12488篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
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   
992.
Nonperturbative nolocal structure of QCD vacuum is well described by instanton model. Specific helicity and flavor structure of zero modes of quarks, in instanton field allows simultaneously to explain some important features of low-and high-energy hadron phenomemology. The basic characteristics of hadron spectrum, partonic sum rules, heavyquark potential etc within the instanton liquid model are briefly discussed.  相似文献   
993.
We investigate the replica symmetry breaking (RSB) in a neighborhood of the instability point of the replica-symmetric solution in the axial quadrupolar glass model. We show that the solution with the first-stage RSB is stable against the subsequent RSB. Although there is no reflection symmetry, the first-stage RSB solution continuously bifurcates from the replica-symmetric one. This implies that our model does not belong to either of the two classes into which spin glasses are usually divided.  相似文献   
994.
An approximate model of a spacetime foam is presented. It is supposed that in the spacetime foam each quantum handle is like to an electric dipole and therefore the spacetime foam is similar to a dielectric. If we neglect of linear sizes of the quantum handle then it can be described with an operator containing a Grassman number and either a scalar or a spinor field. For both fields the Lagrangian is presented. For the scalar field it is the dilaton gravity + electrodynamics and the dilaton field is a dielectric permeability. The spherically symmetric solution in this case give us the screening of a bare electric charge surrounded by a polarized spacetime foam and the energy of the electric field becomes finite one. In the case of the spinor field the spherically symmetric solution give us a ball of the polarized spacetime foam filled with the confined electric field. It is shown that the full energy of the electric field in the ball can be very big.  相似文献   
995.
996.
The stress–strain state of rectangular plates with a variable thickness and constant weight is analyzed. The laws of variation in the thickness are specified to depend on parameters so that the plate weight remains constant for any of their values. To solve the problem, discrete Fourier series are used, which makes it possible to reduce a two-dimensional problem to one-dimensional. Calculation results are presented.  相似文献   
997.
The microhardness and content of carbon in electroplated gold coatings were studied as influenced by the operation time of citrate and citrate-phosphate gold-plating electrolytes. Such physicomechanical properties as porosity, microhardness, internal stress, plasticity, and microstructure of electroless-plated and electroplated nickel coatings were studied and analyzed.  相似文献   
998.
We consider the inverse problem for the identification of the coefficient in a parabolic equation. The model is applied to describe the functioning of a hierarchical structure [1]; it is also relevant for heat-conduction theory [2]. Unique solvability of the inverse problem is proved.  相似文献   
999.
Mathematical Notes -  相似文献   
1000.
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   
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