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   225329篇
  免费   2765篇
  国内免费   708篇
化学   116762篇
晶体学   3560篇
力学   9925篇
综合类   5篇
数学   24590篇
物理学   73960篇
  2021年   2198篇
  2020年   2204篇
  2019年   2403篇
  2018年   3052篇
  2017年   2932篇
  2016年   4403篇
  2015年   2860篇
  2014年   4397篇
  2013年   10408篇
  2012年   8829篇
  2011年   10541篇
  2010年   7176篇
  2009年   6886篇
  2008年   9434篇
  2007年   9366篇
  2006年   9041篇
  2005年   7984篇
  2004年   7369篇
  2003年   6456篇
  2002年   6257篇
  2001年   6859篇
  2000年   5336篇
  1999年   4074篇
  1998年   3223篇
  1997年   3223篇
  1996年   3046篇
  1995年   2779篇
  1994年   2645篇
  1993年   2529篇
  1992年   2829篇
  1991年   2773篇
  1990年   2717篇
  1989年   2483篇
  1988年   2505篇
  1987年   2514篇
  1986年   2324篇
  1985年   3028篇
  1984年   3259篇
  1983年   2668篇
  1982年   2860篇
  1981年   2827篇
  1980年   2665篇
  1979年   2770篇
  1978年   2861篇
  1977年   2852篇
  1976年   2920篇
  1975年   2703篇
  1974年   2675篇
  1973年   2806篇
  1972年   1781篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
102.
Baik  Hyungryul  Kim  Changsub  Kwak  Sanghoon  Shin  Hyunshik 《Geometriae Dedicata》2021,214(1):399-426
Geometriae Dedicata - We show that an Anosov map has a geodesic axis on the curve graph of the torus. The direct corollary of our result is the stable translation length of an Anosov map on the...  相似文献   
103.
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   
104.
105.
The European Physical Journal E - The isothermal gas adsorption of two hexane isomers (n-hexane and cyclohexane) in the mesopores of MCM-41 silica have been investigated by small angle neutron...  相似文献   
106.
107.
Parallel preconditioners are presented for the solution of general linear systems of equations. The computation of these preconditioners is achieved by orthogonal projections related to the Frobenius inner product. So, minM∈??AM?IF and matrix M0∈?? corresponding to this minimum (?? being any vectorial subspace of ??n(?)) are explicitly computed using accumulative formulae in order to reduce computational cost when subspace ?? is extended to another one containing it. Every step, the computation is carried out taking advantage of the previous one, what considerably reduces the amount of work. These general results are illustrated with the subspace of matrices M such that AM is symmetric. The main application is developed for the subspace of matrices with a given sparsity pattern which may be constructed iteratively by augmenting the set of non‐zero entries in each column. Finally, the effectiveness of the sparse preconditioners is illustrated with some numerical experiments. Copyright © 2002 John Wiley & Sons, Ltd.  相似文献   
108.
By making creep and recoverable creep measurements of a nearly monodisperse low molecular weight poly(methyl phenyl siloxane) sample, we have found on decreasing temperature towardsT g that there is continuously a change in the viscoelastic spectrum concomitant with a decrease of the steadystate recoverable compliance. This behavior is exactly the same as previously observed in low molecular weight poly(styrene), proving that this spectacular anomaly in the viscoelasticity of low molecular weight polymers is general and deserves an explanation. Photon correlation spectroscopic measurements performed on the same sample have extended the observation of the viscoelastic response to shorter times and the result corroborates the trend of variation established by the creep data.Dedicated to Prof.Dr. E. W. Fischer on his 65th Birthday. Prof.Dr. Fischer is known for his valuable contribution to fosterine, international collaboration of research in polymer science. This work is an example of his contribution because it would not be possible without him bringing us together. One of us (KLN) would like to take this opportunity to thank Prof. Dr. Fischer for his unwaiving support of the 1st (Crete) and the 2nd (Alicante) International Discussion Meeting on Relaxations in Complex Systems  相似文献   
109.
ONAPAIROFNONISOMETRICISOSPECTRALDOMAINSWITHFRACTALBOUNDARIESANDTHEWEYLBERRYCONJECTURESLEEMAN,B.D.CHENHUAManuscriptrec...  相似文献   
110.
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