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   392482篇
  免费   2011篇
  国内免费   554篇
化学   183481篇
晶体学   5851篇
力学   22402篇
综合类   9篇
数学   56248篇
物理学   127056篇
  2020年   4186篇
  2019年   5067篇
  2018年   7485篇
  2017年   7669篇
  2016年   9604篇
  2015年   4503篇
  2014年   8502篇
  2013年   15967篇
  2012年   12974篇
  2011年   15223篇
  2010年   12689篇
  2009年   12870篇
  2008年   14663篇
  2007年   14439篇
  2006年   12930篇
  2005年   11250篇
  2004年   10871篇
  2003年   10067篇
  2002年   10363篇
  2001年   10489篇
  2000年   8138篇
  1999年   6211篇
  1998年   5700篇
  1997年   5492篇
  1996年   5018篇
  1995年   4470篇
  1994年   4514篇
  1993年   4514篇
  1992年   4597篇
  1991年   5082篇
  1990年   5007篇
  1989年   5056篇
  1988年   4704篇
  1987年   4776篇
  1986年   4468篇
  1985年   5358篇
  1984年   5552篇
  1983年   4728篇
  1982年   4982篇
  1981年   4640篇
  1980年   4292篇
  1979年   4931篇
  1978年   5105篇
  1977年   5305篇
  1976年   5456篇
  1975年   5063篇
  1974年   4894篇
  1973年   5138篇
  1972年   4314篇
  1971年   3949篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
21.
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   
22.
On the basis of the method of successive approximations in formal series we construct systems of particular solutions of the equations of planar and flexural harmonic vibrations of thin rectilinear anisotropic plates with a plane of symmetry of elastic properties parallel to the faces. The solutions constructed are classified as special sk-functions of generalized complex variables. Translated fromTeoreticheskaya i Prikladnaya Mekhanika No. 24, 1993, pp. 54–61.  相似文献   
23.
The radiation emitted by charged, scalar particles in a Schwarzschild field with maximal acceleration corrections is calculated classically and in the tree approximation of quantum field theory. In both instances the particles emit radiation that has characteristics similar to those of gamma-ray bursters.  相似文献   
24.
Surface relief formation at holographic recording on amorphous selenium films was demonstrated and investigated. The presence of this optical phase modulation component is essential for ensuring significant, stable and erasable optical recording in a-Se films at 290–320 K temperatures, where conventional photodarkening was known as insignificant and unstable. Photocrystallization can only be observed in super-exposed a-Se films at the given experimental conditions of hologram recording. Erasing behavior of surface relief gratings under heat treatment was also investigated in order to reveal further details of the mechanism. Photoinduced structural transformations within the amorphous phase, connected to local ordering under the condition of light-induced fluidity, are proposed as an explanation for the relief formation and erasing. The observed reversible optical recording process may be useful for the various optoelectronic applications of photoconductive a-Se layers. Received: 12 June 2000 / Accepted: 6 June 2001 / Published online: 30 August 2001  相似文献   
25.
This paper reports on the first experimental observation of quantum-well states and sp-type resonances in thin single-crystal gold, silver, and copper layers formed on single-crystal W(110) surfaces, which result from spatial localization of Bloch-type electronic wave functions in a quantum well with potential barriers at the vacuum/metal and metal/W(110) interfaces. The quantization of the valence-band electronic structure in Au/W(110), Ag/W(110), and Cu/W(110) systems was studied experimentally using angle-resolved photoelectron spectroscopy.  相似文献   
26.
Estimates of a rate of convergence of orderO(n –1) are obtained for integral functionals of an empirical process.Translated fromTeoriya Sluchainykh Protsessov, Vol. 15, pp. 10–16, 1987.  相似文献   
27.
Translated fromProblemy Ustoichivosti Stokhasticheskikh Modelei. Trudy Seminara, 1988, pp. 84–92.  相似文献   
28.
A mixed boundary-value problem for the nonlinear Schrödinger equation and its generalization is studied by the method used for the inverse scattering problem. A connection is established between conservation laws and boundary conditions in integrable boundary-value problems for higher nonlinear Schrödinger equations. It is shown that the generalized boundary-value problem requires a joint consideration of regular and singular solutions for the nonlinear Schrödinger equation with repulsion.Translated from Zapiski Nauchnykh Seminarov Leningradskogo Otdeleniya Matematicheskogo Instituta im. V. A. Steklova AN SSSR, Vol. 169, pp. 151–165, 1988.  相似文献   
29.
30.
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