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   1317664篇
  免费   29598篇
  国内免费   7735篇
化学   655674篇
晶体学   20321篇
力学   74246篇
综合类   103篇
数学   239965篇
物理学   364688篇
  2021年   13441篇
  2020年   15876篇
  2019年   16013篇
  2018年   12687篇
  2016年   27673篇
  2015年   20698篇
  2014年   30284篇
  2013年   74090篇
  2012年   36703篇
  2011年   32974篇
  2010年   36656篇
  2009年   39142篇
  2008年   32832篇
  2007年   28360篇
  2006年   34595篇
  2005年   27300篇
  2004年   28536篇
  2003年   27175篇
  2002年   28359篇
  2001年   26597篇
  2000年   23797篇
  1999年   22039篇
  1998年   20795篇
  1997年   20813篇
  1996年   21010篇
  1995年   19094篇
  1994年   18521篇
  1993年   18082篇
  1992年   17831篇
  1991年   18169篇
  1990年   17397篇
  1989年   17422篇
  1988年   17019篇
  1987年   17030篇
  1986年   15936篇
  1985年   22387篇
  1984年   23681篇
  1983年   19891篇
  1982年   21589篇
  1981年   20836篇
  1980年   20196篇
  1979年   20306篇
  1978年   21638篇
  1977年   21220篇
  1976年   20914篇
  1975年   19649篇
  1974年   19255篇
  1973年   19785篇
  1972年   14263篇
  1967年   12490篇
排序方式: 共有10000条查询结果,搜索用时 31 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