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   203598篇
  免费   1301篇
  国内免费   431篇
化学   105046篇
晶体学   3393篇
力学   10281篇
综合类   10篇
数学   21914篇
物理学   64686篇
  2021年   1989篇
  2020年   2026篇
  2019年   2576篇
  2018年   3669篇
  2017年   3689篇
  2016年   4826篇
  2015年   2362篇
  2014年   4320篇
  2013年   8630篇
  2012年   6875篇
  2011年   8091篇
  2010年   6478篇
  2009年   6667篇
  2008年   7663篇
  2007年   7630篇
  2006年   6729篇
  2005年   5952篇
  2004年   5669篇
  2003年   5189篇
  2002年   5169篇
  2001年   5612篇
  2000年   4141篇
  1999年   3136篇
  1998年   2704篇
  1997年   2760篇
  1996年   2544篇
  1995年   2213篇
  1994年   2333篇
  1993年   2228篇
  1992年   2523篇
  1991年   2646篇
  1990年   2554篇
  1989年   2622篇
  1988年   2532篇
  1987年   2553篇
  1986年   2411篇
  1985年   3034篇
  1984年   3101篇
  1983年   2598篇
  1982年   2563篇
  1981年   2528篇
  1980年   2336篇
  1979年   2709篇
  1978年   2672篇
  1977年   2871篇
  1976年   2872篇
  1975年   2664篇
  1974年   2602篇
  1973年   2711篇
  1972年   2085篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
This paper is in answer to the comment on the GRG paper: Lockerbie N.A. Gen. Rel. Grav. 36, 593 (2004), made by A.V. Sanders, G.T. Gillies (ibid.). N. A. Lockerbie is a member of the STEP (Satellite Test of the Equivalence Principle) Science Study Team, and an Associate of the Institute for Gravitational Research at the University of Glasgow, Scotland, UK.  相似文献   
102.
The spectra of the intensity fluctuations of light scattered by large (erythrocytes of whole blood) and small (vesicles of surgical bile) particles in natural conditions were studied. It is shown that photon correlation spectroscopy can be used in analysis of variations in the size of biological particles in normal and pathological conditions and as an express method of noninvasive diagnostics of diseases.  相似文献   
103.
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 55, No. 4, pp. 613–618, October, 1991.  相似文献   
104.
The behavior of the edges of cuts in shallow shells with the symmetric combined action of tension and flexure is investigated. For shells of different curvature with one and two parallel or collinear cuts, the load region in which there is no contact of the cut edges in the course of shell deformation is determined.Translated from Teoreticheskaya i Prikladnaya Mekhanika, No. 19, pp. 98–100, 1988.  相似文献   
105.
Modifications are introduced into the large-particle method to make it possible to use the method in arbitrary nonrectangular computing nets in the study of the flow of an ideal compressible gas over mobile thin permeable membranes. A problem in the aeroelasticity of a parachute is stated. An example is given of the solution of a problem in the stationary formulation for an axially symmetric parachute in the wake of a cylindrical leading body for supersonic flow.Translated fromDinamicheskie Sistemy, No. 6, 1987, pp. 16–22  相似文献   
106.
107.
Results of an experimental observation of the voltage oscillations associated with a discrete tunneling of holes in porous silicon at room temperature are presented. The noise characteristics of diode structures with a porous silicon interlayer formed on heavily boron-doped silicon single crystals are studied. Peaks of excessive noise are observed at frequencies of ~1 MHz, at which single-electron oscillations should be expected. The peak noise power is found to increase with current according to the ~2.5 power law and, at a current density of 0.15 A/cm2, to exceed the noise power of the receiver by three to four orders of magnitude. The complex shape of the noise spectrum and its extension to the higher frequency region with increasing current are explained by the three-dimensionality of the system of nanometer-sized silicon grains embedded in insulating silicon dioxide of porous silicon.  相似文献   
108.
In this paper we study a stochastic differential equation with multivalued maximally monotone drift operator. Under certain assumptions on the growth of the multivalued operator we prove a theorem on the existence and uniqueness of the solution of such an equation.Translated fromTeoriya Sluchainykh Protsessov, Vol. 15, pp. 54–59, 1987.  相似文献   
109.
110.
A simple model for a distributed self-oscillatory system with cubic nonlinearity and delay is presented. Conditions for oscillation self-excitation and stationary oscillation conditions, as well as the stability of the oscillations, are analyzed. Nonstationary self-modulation regimes (including conditions of complex dynamics and chaos) are simulated numerically over a wide range of control parameters. As the factor of nonequilibrium grows, regular and chaotic regimes alternate in a complex manner. The transitions to chaos may follow all scenarios known for finite-dimensional systems. The model suggested is somewhat akin to a number of earlier finite-dimensional models aimed at studying mode competition in resonance electron masers.  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