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   3605篇
  免费   294篇
  国内免费   297篇
化学   34篇
力学   388篇
综合类   61篇
数学   3389篇
物理学   324篇
  2023年   31篇
  2022年   21篇
  2021年   43篇
  2020年   87篇
  2019年   77篇
  2018年   87篇
  2017年   85篇
  2016年   90篇
  2015年   34篇
  2014年   117篇
  2013年   285篇
  2012年   104篇
  2011年   137篇
  2010年   124篇
  2009年   201篇
  2008年   229篇
  2007年   225篇
  2006年   218篇
  2005年   193篇
  2004年   169篇
  2003年   170篇
  2002年   194篇
  2001年   156篇
  2000年   132篇
  1999年   145篇
  1998年   113篇
  1997年   114篇
  1996年   84篇
  1995年   54篇
  1994年   60篇
  1993年   26篇
  1992年   40篇
  1991年   52篇
  1990年   32篇
  1989年   19篇
  1988年   21篇
  1987年   27篇
  1986年   18篇
  1985年   28篇
  1984年   20篇
  1983年   16篇
  1982年   14篇
  1981年   17篇
  1980年   16篇
  1979年   15篇
  1978年   13篇
  1977年   12篇
  1976年   5篇
  1974年   6篇
  1973年   9篇
排序方式: 共有4196条查询结果,搜索用时 15 毫秒
1.
Over the last 20 years a large number of algorithms has been published to improve the speed and domain of convergence of continued fractions. In this survey we show that these algorithms are strongly related. Actually, they essentially boil down to two main principles.We also prove some results on asymptotic expansions of tail values of limit periodic continued fractions.Dedicated to Luigi Gatteschi on his seventieth birthdayThis research was partially supported by The Norwegian Research Council and by the HMC project ROLLS, under contract CHRX-CT93-0416.  相似文献   
2.
This paper studies the linear EV model when replicate observations are made only on independent variables. We construct the estimates of regression coefficients and prove the consistency and asymptotic normality under some proper conditions. Results obtained reveal the difference between the case where the independent and dependent variables are observed repeatedly and simultaneously and the case studied in this article.  相似文献   
3.
We find an explicit function approximating at high energies the kernel of the scattering matrix with arbitrary accuracy. Moreover, the same function gives all diagonal singularities of the kernel of the scattering matrix in the angular variables. This paper is dedicated to Jean-Michel Combes on the occasion of his sixtieth birthday.  相似文献   
4.
Different versions of the Darboux–Weinstein theorem guarantee the existence of action–angle-type variables and the harmonic-oscillator variables in a neighborhood of isotropic tori in the phase space. The procedure for constructing these variables is reduced to solving a rather complicated system of partial differential equations. We show that this system can be integrated in quadratures, which permits reducing the problem of constructing these variables to solving a system of quadratic equations. We discuss several applications of this purely geometric fact in problems of classical and quantum mechanics.  相似文献   
5.
The semi‐iterative method (SIM) is applied to the hyper‐power (HP) iteration, and necessary and sufficient conditions are given for the convergence of the semi‐iterative–hyper‐power (SIM–HP) iteration. The root convergence rate is computed for both the HP and SIM–HP methods, and the quotient convergence rate is given for the HP iteration. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   
6.
给出引理解决了方程非振动解与其各阶导数的符号关系,并由此得到了若干判别准则,用于判别三阶线性脉冲微分方程解的振动性与渐近性,举例说明了准则的有效性。本文推广了相关文献的结果。  相似文献   
7.
In this paper, we consider an autonomous predator-prey Lotka-Volterra system in which individuals in the population may belong to one of two classes: the immatures and the matures, the age to maturity is represented by a time delay. By using eigenvalue analysis, principal term analyze method, reduction to absurdity, and iterative method, we obtain some simple conditions for global asymptotic stability of the unique positive equilibrium point. Moreover, a condition that the prey population in the system get extinction and the predator population in the system get permanence will be obtained. Meanwhile the theorems extend the corresponding conclusions in which there have no two stage structures.  相似文献   
8.
We obtain exponential upper bounds for tails of distributions of generalized L-statistics based on a sample from an exponential distribution. We prove the asymptotic normality of generalized L-statistics based on a sample from the uniform distribution on [0,1] and of L-statistics with decomposed kernels (without any restrictions on the sample distribution type).  相似文献   
9.
We consider elliptic and parabolic problems in unbounded domains. We give general existence and regularity results in Besov spaces and semi‐explicit representation formulas via operator‐valued fundamental solutions which turn out to be a powerful tool to derive a series of qualitative results about the solutions. We give a sample of possible applications including asymptotic behavior in the large, singular perturbations, exact boundary conditions on artificial boundaries and validity of maximum principles. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   
10.
The main purpose of this paper is to use a mean value theorem of Dirichlet L-functions to study the asymptotic property of a hybrid mean value of a generalized Cochrane sum, and give an interesting mean value formula.2000 Mathematics Subject Classification: Primary—11F20; Secondary—11F99  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