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   372363篇
  免费   1882篇
  国内免费   649篇
化学   160943篇
晶体学   5430篇
力学   23270篇
综合类   20篇
数学   63224篇
物理学   122007篇
  2021年   3199篇
  2020年   3556篇
  2019年   4373篇
  2018年   11981篇
  2017年   12445篇
  2016年   10880篇
  2015年   4140篇
  2014年   7166篇
  2013年   12456篇
  2012年   13415篇
  2011年   20646篇
  2010年   14927篇
  2009年   15240篇
  2008年   18959篇
  2007年   21362篇
  2006年   10314篇
  2005年   12542篇
  2004年   10400篇
  2003年   10347篇
  2002年   9395篇
  2001年   7990篇
  2000年   6472篇
  1999年   4651篇
  1998年   4412篇
  1997年   4244篇
  1996年   4016篇
  1995年   3501篇
  1994年   3543篇
  1993年   3559篇
  1992年   3563篇
  1991年   3979篇
  1990年   3976篇
  1989年   4010篇
  1988年   3731篇
  1987年   3818篇
  1986年   3507篇
  1985年   4068篇
  1984年   4322篇
  1983年   3704篇
  1982年   3906篇
  1981年   3555篇
  1980年   3331篇
  1979年   3858篇
  1978年   3953篇
  1977年   4028篇
  1976年   4174篇
  1975年   3889篇
  1974年   3763篇
  1973年   3958篇
  1972年   3398篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
171.
172.
Ganenkova  E. G.  Starkov  V. V. 《Mathematical Notes》2019,105(1-2):216-226

Differential inequalities for polynomials generalizing the well-known Smirnov, Rahman, Schmeisser, and Bernstein inequalities are obtained.

  相似文献   
173.
Driven and non-equilibrium quantum states of matter have attracted growing interest in both theoretical and experimental studies in condensed matter physics. Recent progress in realizing transient collective states in driven or pumped Dirac materials (DMs) is reviewed herein. In particular, the focus is on optically pumped DMs which are a promising platform for transient excitonic instabilities. Optical pumping combined with the linear (Dirac) dispersion of the electronic spectrum offers a knob for tuning the effective interaction between the photoexcited electrons and holes, and thus provides a way of reducing the critical coupling for excitonic instability. As a result, a transient excitonic condensate could be achieved in a pumped DM while it is not feasible in equilibrium. A unifying theoretical framework is provided for describing transient collective states in 2D and 3D DMs. The experimental signatures are described and numerical estimates of the size of the dynamically induced excitonic gaps and the values of the critical temperatures for several specific systems, are summarized. In addition, general guidelines for identifying promising material candidates are discussed. Finally, comments are provided regarding recent experimental efforts in realizing transient excitonic condensate in pumped DMs, and outstanding issues and possible future directions are outlined.  相似文献   
174.
Radiophysics and Quantum Electronics - We consider whether it is possible in principle to retrieve the key parameters of the mixed layer in the upper ocean (its thickness, bulk eddy viscosity and...  相似文献   
175.
Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques - A method for studying the magnetic dynamics of endofullerenes M@C2n (2n = 60, 70, …) and their derivatives,...  相似文献   
176.
Vlasov  V. V.  Rautian  N. A. 《Doklady Mathematics》2021,103(1):10-13
Doklady Mathematics - Integro-differential equations with unbounded operator coefficients in a Hilbert space are studied. The equations under consideration are abstract hyperbolic equations...  相似文献   
177.
The structure, chemical composition, and magnetic properties of electrochemically deposited nanocrystalline Co-Ni-Fe films were investigated using a number of techniques. A high saturation magnetic induction up to B s = 21 kG was attained. An enhancement of the saturation magnetization compared to the ideal anticipated one was revealed, which correlated with the nonlinear behavior of the structural phase composition and lattice parameters with the change of the composition. The text was submitted by the authors in English.  相似文献   
178.
Methods for phase stabilization of ammonium nitrate were sought for in order to considerably expand the application area of this oxidizing agent in various-purpose self-combustible formulations, including that in a new generation of gas-generating formulations for automobile air bags. New methods for stabilization of ammonium nitrate were studied and, in particular, a search was made for organic compounds that can stabilize ammonium nitrate even at their low content. The mechanism of phase state stabilization of ammonium nitrate by compounds of this kind was examined.  相似文献   
179.
Kinetic, sorption and selectivity properties of commercial adsorbents are improved by adding petroleum residues (tar asphaltene concentrates) 13% of whole mass. Obtained adsorbents can be used for selective extraction of nobel metals from multicomponent polymetallic solutions of heavy metals and fro sewages purification for removing arsenic.  相似文献   
180.
Using the simplest (sinusoidal) corrugation profile in the approximation of absence of losses in the material as an example, we study the regimes of complete transformation of an incident wave to the diffraction lobe by a corrugated metal surface or a corrugated interface of two dielectric media. A numerical-intuitive pattern of appearance and evolution of such regimes with increasing corrugation amplitude is revealed. It is shown that the regimes of complete transformation of an incident wave to the diffraction lobe are possible in both the case of autocollimation and the case of a considerable deviation from it. The examination is based on a numerical method of solving the integral equation by means of a specially created interactive processing system in Visual Fortran.  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