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   77799篇
  免费   568篇
  国内免费   111篇
化学   41361篇
晶体学   1261篇
力学   3282篇
综合类   1篇
数学   7858篇
物理学   24715篇
  2022年   626篇
  2021年   874篇
  2020年   968篇
  2019年   1105篇
  2018年   1597篇
  2017年   1687篇
  2016年   2153篇
  2015年   1024篇
  2014年   1724篇
  2013年   3277篇
  2012年   2908篇
  2011年   3286篇
  2010年   2642篇
  2009年   2637篇
  2008年   3007篇
  2007年   2881篇
  2006年   2775篇
  2005年   2436篇
  2004年   2243篇
  2003年   2075篇
  2002年   2135篇
  2001年   2237篇
  2000年   1624篇
  1999年   1252篇
  1998年   1128篇
  1997年   1037篇
  1996年   896篇
  1995年   834篇
  1994年   813篇
  1993年   814篇
  1992年   867篇
  1991年   936篇
  1990年   879篇
  1989年   905篇
  1988年   821篇
  1987年   770篇
  1986年   743篇
  1985年   869篇
  1984年   962篇
  1983年   819篇
  1982年   837篇
  1981年   748篇
  1980年   702篇
  1979年   770篇
  1978年   895篇
  1977年   915篇
  1976年   809篇
  1975年   774篇
  1974年   794篇
  1973年   761篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
151.
Local and nonlocal coercive estimates in Lebesgue, Hölder, and Morrey–Campanato spaces are proved for solutions of linear stationary systems of hydrodynamic type. For this purpose, the technique proposed by Italian mathematicians for the study of solutions to equations and systems of elliptic and parabolic types is developed. Bibliography: 14 titles.  相似文献   
152.
153.
Within the framework of microscopic fluctuation-dissipation theory, we obtain the stochastic equation describing the Brownian motion of an electron in the phonon field of the crystal lattice. An expression for the Green’s function of the phonon field is found in general form and for the case of linear phonon-variable interaction of an electron with the phonon field with allowance for the potential screening of crystal-lattice nuclei. An expression for the phonon drag acting on a conduction electron in the lattice field is found and analyzed with allowance for the interaction. Frequency dependence of the coefficient of the phonon drag acting on a conduction electron is studied and the contribution of the electron-phonon interaction to the effective mass of a charge carrier is determined.__________Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 48, No. 3, pp. 249–268, March 2005.  相似文献   
154.
155.
156.
157.
Modification of Paving Asphalts with Sulfur   总被引:2,自引:0,他引:2  
Sulfur dissolved in oil components of asphalt is a binder, filler, and chemical co-reagent at once. The structure of sulfur-extended asphalt depends on its formula and heating temperature. Road pavement based on sulfur-extended asphalt demonstrates higher durability as compared to that with the conventional binders.  相似文献   
158.
In this paper, we describe an aircraft loading problem submitted by the French military agency (DGA) as part of a more general military airlift planning problem. It can be viewed as a kind of bi-dimensional bin-packing problem, with heterogeneous bins and several additional constraints. We introduce two-phase methods for solving this NP-hard problem. The first phase consists in building good initial solutions, thanks to two fast algorithms: a list-based heuristic and a loading pattern generation method. Both algorithms call a constraint-based subroutine, able to determine quickly if the items already loaded can be reshuffled to accommodate a new object. The second phase improves these preliminary solutions using local search techniques. Results obtained on real data sets are presented.  相似文献   
159.
Amplitude equations, as well as the effective dispersion and nonlinearity parameters, which define the dynamics of a wave packet formed by two strongly coupled modes, are derived with allowance for the frequency dependence of the linear mode coupling coefficient. These equations are used to study the onset of the modulation instability of the two-mode wave packet, soliton-like pulses, and compression modes. Unlike single-mode systems, the last two effects in optical waveguides may arise for both a negative and positive disper-sion of the waveguide material.  相似文献   
160.
Ab initio MP2 calculations with several basis sets proved the existence of a stable benzonitrile dimer with a planar structure and a short contact between the H atom of one molecule and the N atom of another. The structure is greatly stabilized by attraction between the neighboring oppositely directed dipoles and donor-acceptor interaction between the orbital of the lone electron pair of the N′ atom and the vacant antibonding orbital localized on the C-H bond.Original Russian Text Copyright © 2004 by O. V. Sizova, E. P. Sokolova, V. I. Baranovskii, D. A. Rozmanov, and O. A. Tomashenko__________Translated from Zhurnal Strukturnoi Khimii, Vol. 45, No. 5, pp. 807–815, September–October, 2004.  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