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   205255篇
  免费   1395篇
  国内免费   429篇
化学   106199篇
晶体学   3404篇
力学   10341篇
综合类   10篇
数学   22054篇
物理学   65071篇
  2021年   2001篇
  2020年   2042篇
  2019年   2580篇
  2018年   3669篇
  2017年   3702篇
  2016年   4872篇
  2015年   2408篇
  2014年   4353篇
  2013年   8671篇
  2012年   6950篇
  2011年   8193篇
  2010年   6520篇
  2009年   6704篇
  2008年   7756篇
  2007年   7716篇
  2006年   6787篇
  2005年   6015篇
  2004年   5707篇
  2003年   5233篇
  2002年   5220篇
  2001年   5647篇
  2000年   4173篇
  1999年   3152篇
  1998年   2718篇
  1997年   2776篇
  1996年   2560篇
  1995年   2232篇
  1994年   2349篇
  1993年   2257篇
  1992年   2548篇
  1991年   2666篇
  1990年   2574篇
  1989年   2641篇
  1988年   2547篇
  1987年   2570篇
  1986年   2428篇
  1985年   3055篇
  1984年   3122篇
  1983年   2612篇
  1982年   2586篇
  1981年   2550篇
  1980年   2357篇
  1979年   2725篇
  1978年   2695篇
  1977年   2887篇
  1976年   2889篇
  1975年   2670篇
  1974年   2615篇
  1973年   2726篇
  1972年   2095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