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   203709篇
  免费   1305篇
  国内免费   433篇
化学   105208篇
晶体学   3398篇
力学   10279篇
综合类   10篇
数学   21882篇
物理学   64670篇
  2021年   1980篇
  2020年   2029篇
  2019年   2588篇
  2018年   3664篇
  2017年   3673篇
  2016年   4814篇
  2015年   2356篇
  2014年   4304篇
  2013年   8608篇
  2012年   6859篇
  2011年   8070篇
  2010年   6466篇
  2009年   6653篇
  2008年   7662篇
  2007年   7618篇
  2006年   6737篇
  2005年   5951篇
  2004年   5670篇
  2003年   5182篇
  2002年   5169篇
  2001年   5617篇
  2000年   4151篇
  1999年   3145篇
  1998年   2704篇
  1997年   2769篇
  1996年   2546篇
  1995年   2220篇
  1994年   2335篇
  1993年   2238篇
  1992年   2534篇
  1991年   2648篇
  1990年   2559篇
  1989年   2632篇
  1988年   2539篇
  1987年   2558篇
  1986年   2420篇
  1985年   3047篇
  1984年   3114篇
  1983年   2607篇
  1982年   2572篇
  1981年   2534篇
  1980年   2344篇
  1979年   2717篇
  1978年   2681篇
  1977年   2884篇
  1976年   2881篇
  1975年   2672篇
  1974年   2611篇
  1973年   2723篇
  1972年   2092篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
101.
We investigate the application of the fictitious region method to fourth-order quasilinear elliptical equations with Dirichlet and Neumann conditions. Convergence bounds are established for two versions of the fictitious region method.Translated from Vychislitel'naya i Prikladnaya Matematika, No. 56, pp. 21–29, 1985  相似文献   
102.
With the help of the apparatus of tensors with values in the Atiyah-Kähler algebra (the apparatus of lambda tensors), a new representation for the relativistic equation of field theory is proposed. The circle of questions under consideration is standard for investigations concerning the theory of the Dirac equation (in this paper, we treat no problems dealing with second quantization).  相似文献   
103.
104.
105.
106.
107.
108.
Bismuth, antimony and its alloys are the typical representatives of a class of semimetals, which electric conductance is lower in 102-103 times, than of usual well conducting an electrical current metals. The alloys bismuth with antimony have semi-conductor properties in wide area of compositions at temperatures below 77 °K. The semimetals are rather perspective materials from the point of view of their probable application in various devices [1,2,3].In present time the semimetal alloys BiSb have wide application in thermoelectric generators and refrigerators. In work [3] the opportunity of use of semimetals BiSb with percentage content of Bi and Sb from 8 % up to 25 % was shown as high-sensitivity and of small inertion indicators of the mm range radiation where thermoelectric effect is used. The principle of action of such indicators is based on occurrence of temperature gradient in a semimetal crystal BiSb that has two contacts of the various area with flowing electrical current. Basic element of such device is the dot contact metal - semimetal. One of the main characteristics is volt-watt sensitivity of metal-semimetal BiSb contact which calculating is shown in present work.  相似文献   
109.
Nonlinear (at the second-harmonic frequency of the incident light) optical reflection by two-dimensional magnetic superstructures is theoretically studied. A square lattice of magnetic dots and a hexagonal lattice of magnetic bubbles (cylindrical magnetic domains) are considered. Because the periods of these structures are comparable with the wavelengths of the fundamental and the second-harmonic radiation, it would be possible to observe diffraction at the second-harmonic frequency. A polarization analysis of nonlinearly diffracted radiation is performed and the numbers of observable diffraction orders for the above structures are estimated. Received: 10 January 2002 / Published online: 11 June 2002  相似文献   
110.
A cluster mechanism is considered for the detachment of particles when the surface of a high-temperature superconducting target absorbs laser pulses. By proposing a fractal nature for the surface, one can model it as an assembly of a large number of nonlinear oscillators (clusters). Utilizing the method of sudden perturbations, a calculation was made of the probability of dissociation of these oscillators, i.e., of the detachment of clusters from the surface. The calculated probability decreases rapidly as the power density of the laser radiation is reduced to some limiting value. This is in agreement with experiments. State Institute of Sensory Microelectronics. Siberian Branch of the Russian Academy of Sciences. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 6, pp. 73–77, June, 1997.  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