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   84283篇
  免费   6931篇
  国内免费   5399篇
化学   24465篇
晶体学   1813篇
力学   3889篇
综合类   415篇
数学   21300篇
物理学   44731篇
  2022年   296篇
  2021年   385篇
  2020年   712篇
  2019年   1024篇
  2018年   965篇
  2017年   690篇
  2016年   569篇
  2015年   506篇
  2014年   1227篇
  2013年   2029篇
  2012年   1373篇
  2011年   1968篇
  2010年   2522篇
  2009年   7119篇
  2008年   8192篇
  2007年   6649篇
  2006年   6113篇
  2005年   4186篇
  2004年   3967篇
  2003年   4170篇
  2002年   5398篇
  2001年   3900篇
  2000年   3642篇
  1999年   3503篇
  1998年   2873篇
  1997年   1996篇
  1996年   1834篇
  1995年   2253篇
  1994年   2194篇
  1993年   1647篇
  1992年   1138篇
  1991年   862篇
  1990年   716篇
  1989年   624篇
  1988年   598篇
  1987年   425篇
  1986年   209篇
  1985年   973篇
  1984年   649篇
  1983年   503篇
  1982年   664篇
  1981年   808篇
  1980年   736篇
  1979年   579篇
  1978年   591篇
  1977年   550篇
  1976年   548篇
  1975年   321篇
  1974年   362篇
  1973年   464篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
191.
In this paper we present a method to solve numerically elliptic problems with multi-scale data using multiple levels of not necessarily nested grids. The method consists in calculating successive corrections to the solution in patches whose discretizations are not necessarily conforming. It resembles the FAC method (see Math. Comp. 46 (174) (1986) 439–456) and its convergence is obtained by a domain decomposition technique (see Math. Comp. 57 (195) (1991) 1–21). However it is of much more flexible use in comparison to the latter. To cite this article: R. Glowinski et al., C. R. Acad. Sci. Paris, Ser. I 337 (2003).  相似文献   
192.
Summary This article provides a glimpse of some of the highlights of the joint work of Endre Csáki and Pál Révész since 1979. The topics of this short exploration of the rich stochastic milieu of this inspiring collaboration revolve around Brownian motion, random walks and their long excursions, local times and additive functionals, iterated processes, almost sure local and global central limit theorems, integral functionals of geometric stochastic processes, favourite sites--favourite values and jump sizes for random walk and Brownian motion, random walking in a random scenery, and large void zones and occupation times for coalescing random walks.  相似文献   
193.
矩阵方程AXB=D的最小二乘Hermite解及其加权最佳逼近   总被引:1,自引:0,他引:1  
本中,我们讨论了矩阵方程AXB=D的最小二乘Hermite解,通过运用广义奇异值分解(GSVD),获得了解的通式。此外,对于给定矩阵F,也得到了它的加权最佳逼近表达式。  相似文献   
194.
The fusion evaporation reaction 122Sn(14N, 4n)132La was used to populate the high-spin states of 132La at the beam energy of 60 MeV. A new band consisting of mostly E2 transitions has been discovered. This band has the interesting links to the ground state 2- and the isomeric state 6-. A new transition of energy 351 keV connecting the low-spin states of the positive-parity band based on the πh 11/2 ⊗ νh 11/2 particle configuration, has been found. This has played a very important role in resolving the existing ambiguities and inconsistencies in the spin assignment of the band head. Received: 12 August 2002 / Accepted: 18 March 2003 / Published online: 7 May 2003  相似文献   
195.
该文讨论了一类非线性抛物型方程组解的性质,利用微分方程上、下解方法证明了初值适当小时,方程存在整体解;初值适当大时,解在有限时间上爆破,推广了文献[1]的结果.  相似文献   
196.
该文考虑具有控制系数 A\-0 和系数仅有有限个极点的高阶线性齐次微分方程(1.1)。得到了一个复振荡结果,该结果是J. K. Langley[11]等作者在整系数下相应结果的推广。  相似文献   
197.
In this paper, we use weighted modules ω(?)(f,t)w to study the pointwise approximation on Szasz-type operators, and obtain the direct and converse theorem, as well as characterizations of the pointwise approximation of Jacobi-weighted Szasz-type operators.  相似文献   
198.
Multicrystalline silicon was grown by unidirectional solidification method using the accelerated crucible rotation technique. The application of the accelerated crucible rotation technique in unidirectional solidification method induced growth striations across the axial direction of the grown crystal. This striation pattern was observed from carbon concentration distribution, obtained by using Fourier transform infrared spectroscopy. The generated striation pattern was found to be weak and discontinuous. Some striations were absent, probably due to back melting, caused during each crucible rotation. From the growth striations and applied time period in crucible rotation, the growth rate was estimated by using Fourier transformation analysis.  相似文献   
199.
An exact formalism for the relativistic version of Landau theory of Fermi liquid in presence of strong quantizing magnetic field is developed. Both direct and exchange type interactions with scalar and vector coupling cases are considered.  相似文献   
200.
An effective stability result for generalized Hamiltonian systems is obtained by applying the simultaneous approximation technique due to Lochak. Among these systems, dimensions of action variables and angle variables might be distinct.  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