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   392216篇
  免费   3234篇
  国内免费   882篇
化学   189572篇
晶体学   5970篇
力学   19515篇
综合类   10篇
数学   56615篇
物理学   124650篇
  2020年   2396篇
  2019年   2611篇
  2018年   11279篇
  2017年   12083篇
  2016年   9014篇
  2015年   4043篇
  2014年   5320篇
  2013年   13438篇
  2012年   13837篇
  2011年   23360篇
  2010年   15173篇
  2009年   15228篇
  2008年   20944篇
  2007年   24069篇
  2006年   10877篇
  2005年   15788篇
  2004年   11891篇
  2003年   10964篇
  2002年   9035篇
  2001年   8985篇
  2000年   6989篇
  1999年   5205篇
  1998年   4475篇
  1997年   4310篇
  1996年   4144篇
  1995年   3872篇
  1994年   3818篇
  1993年   3598篇
  1992年   4089篇
  1991年   4133篇
  1990年   3930篇
  1989年   3862篇
  1988年   3829篇
  1987年   3717篇
  1986年   3558篇
  1985年   4632篇
  1984年   4834篇
  1983年   4138篇
  1982年   4399篇
  1981年   4094篇
  1980年   4028篇
  1979年   4324篇
  1978年   4525篇
  1977年   4236篇
  1976年   4366篇
  1975年   4215篇
  1974年   4201篇
  1973年   4351篇
  1972年   2869篇
  1971年   2454篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
111.
An estimate of the factors which influence the rate of growth of filamentary silicon crystals in a standard chloride system using a quartz reactor with hot walls is given. It is shown that a diffusion form of crystallization is observed under the conditions investigated.Voronezh State Technical University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 10, pp. 22–26, October, 1995.  相似文献   
112.
We present the results of an experimental investigation of a RF splitting of57Fe hyperfine lines in the regime of NMR and Mössbauer double resonance. The experiments have been performed as a function of RF field intensity and static magnetic field magnitude. The intensity of the RF components and the separation between them are extremely sensitive to the frequency and amplitude of the RF magnetic field. The RF splitting of hyperfine lines is inversely proportional to the strength of the static magnetic field.  相似文献   
113.
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   
114.
115.
Using an integral theory of grating diffraction we calculate efficiencies greater than 100% if a coating with gain is taken into account. A connection with guided modes is conjectured. The application in optical computing seems to be possible.  相似文献   
116.
Physics and Mathematics Division with Computational Center of the Bashkir Branch of the USSR Academy of Sciences. Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 80, No. 3, pp. 470–473, September, 1989.  相似文献   
117.
This paper presents an alternative to the beta continuous probability distribution for risk analysis. Particular attention has been given to two major applications of distributions, namely project management risk and critical path analysis (PERT). In conjunction with the beta, the triangular and normal distributions are frequently employed in order to give sufficient robustness to risk analysis. The beta distribution, as used in PERT, has a major theoretical implementation flaw. The new distribution was developed to give a possible alternative method of assessing risk. It is shown that the requirement to estimate the most pessimistic variate may be replaced by the probability to exceed the mode. Proposals for other simplifications in risk analysis are discussed. Practical means to validate the most appropriate distributions for risk analysis are outlined, and a cost-data case study is included.  相似文献   
118.
119.
Transport as a consequence of state-dependent diffusion   总被引:1,自引:0,他引:1  
Overdamped particles subject to a drift in a force field with sinusoidal space dependence and also a sinusoidally modulated space-dependent diffusion, with the same period as the drift, experience a net driving force. The resulting current depends on the amplitude of the modulation of the diffusion and is a periodic function of the phase difference between the sinusoidal drift and the sinusoidal modulation of the diffusion. For small modulation amplitudes a particle subject to state-dependent noise behaves the same way as a particle subject to thermal noise but with a drift which, in addition to the sinusoidal term, contains a net force term.Dedicated to Professor Harry Thomas on the occasion of his 60th birthday  相似文献   
120.
Using the method of the tensor Green’s function of the wave equation, the differential and total cross sections for the scattering of surface optical electromagnetic waves (surface plasmon polaritons) by a spherical nanoparticle into surface plasmon polaritons and light have been obtained with the inclusion of the magnetic dipole contribution. Using the example of noble metal systems, it has been shown that the magnetic dipole contribution may significantly affect the angular dependence of the differential cross sections and increase their anisotropy as the plasmon wavelength increases.  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