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   938篇
  免费   19篇
  国内免费   6篇
化学   426篇
晶体学   3篇
力学   33篇
数学   247篇
物理学   254篇
  2022年   9篇
  2021年   21篇
  2020年   11篇
  2019年   13篇
  2018年   8篇
  2017年   10篇
  2016年   13篇
  2015年   14篇
  2014年   15篇
  2013年   41篇
  2012年   33篇
  2011年   41篇
  2010年   29篇
  2009年   28篇
  2008年   47篇
  2007年   42篇
  2006年   40篇
  2005年   36篇
  2004年   20篇
  2003年   22篇
  2002年   24篇
  2001年   11篇
  2000年   20篇
  1998年   6篇
  1997年   6篇
  1996年   10篇
  1995年   10篇
  1994年   15篇
  1993年   12篇
  1992年   13篇
  1991年   7篇
  1990年   19篇
  1989年   10篇
  1988年   9篇
  1987年   6篇
  1986年   16篇
  1985年   12篇
  1984年   15篇
  1983年   18篇
  1982年   15篇
  1981年   15篇
  1980年   9篇
  1979年   12篇
  1978年   11篇
  1977年   18篇
  1976年   12篇
  1975年   12篇
  1974年   11篇
  1973年   10篇
  1968年   7篇
排序方式: 共有963条查询结果,搜索用时 109 毫秒
61.
Although much discussed, the original intent of Problem 10 of the Moscow Mathematical Papyrus continues to be an unresolved question. This essay proposes a possible solution to the issue by joining together aspects of two theories on the subject advanced in the 1930s by W. W. Struve and T. E. Peet. From this point of beginning it is shown that the problem’s “basket” may originally have been intended to be understood as being of a specific actual size, thus revealing a set of correlations and insights regarding early Middle Kingdom mathematical capabilities and grain measurement concerns.  相似文献   
62.
63.
The monoester of itaconic acid with n-decyl alcohol was prepared and polymerized. The polymer was fractionated and characterized by viscometry, size-exclusion chromatography (SEC) and light scattering. Some of the common semiempirical relations for flexible and rigid polymers were used in order to obtain the unperturbed dimensions and the conformational parameters. Thermodynamic and dimensional parameters were determined and calculated. The results are compared with those reported previously for similar compounds.  相似文献   
64.
Middle ear prosthesis: significance in magnetic resonance imaging   总被引:1,自引:0,他引:1  
The Armstrong model of the Schuknecht gel foam and wire prosthesis was tested in the magnetic field of a 1.5 Tesla magnet. The wire component of the prosthesis was found to be non-magnetic. Patients with this prosthesis can therefore undergo MRI examination safely. Two previous articles from the non radiologic literature concerning the magnetic properties of metallic middle ear prostheses are reviewed.  相似文献   
65.
66.
The Wigner distribution has proven to be a useful tool in many quantum problems requiring a joint distribution of position and momentum. In the present paper we develop a joint distribution for spin components within the spirit of the Wigner distribution. This distribution provides an insight into the quantum theory of measurement. We also discuss how one may write joint distributions for two arbitrary noncommuting operators.It is a pleasure to dedicate this paper to Professor John A. Wheeler—physicist, philosopher, poet—an inspiration to us all.Work supported by the Office of Naval Research.  相似文献   
67.
68.
69.
The time‐dependent yield and failure behavior of off‐axis loaded uniaxially oriented polypropylene tape is investigated. The yield and failure behavior is described with an anisotropic viscoplastic model. A viscoplastic flow rule is used with an equivalent stress, based on Hill's anisotropic yield criterion, and the Eyring flow theory combined with a critical equivalent strain definition. This model is based on factorization of the rate and draw ratio dependence and is capable of quantitatively predicting the rate, angle and draw ratio dependence of the yield stress as well as time‐to‐failure in various off‐axis tensile loading conditions characterized solely from the transverse direction. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 2026–2035, 2009  相似文献   
70.
A new wavelet multigrid method   总被引:1,自引:0,他引:1  
The standard multigrid procedure performs poorly or may break down when used to solve certain problems, such as elliptic problems with discontinuous or highly oscillatory coefficients. The method discussed in this paper solves this problem by using a wavelet transform and Schur complements to obtain the necessary coarse grid, interpolation, and restriction operators. A factorized sparse approximate inverse is used to improve the efficiency of the resulting method. Numerical examples are presented to demonstrate the versatility of the method.  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