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   1659篇
  免费   18篇
  国内免费   22篇
化学   1073篇
晶体学   15篇
力学   51篇
数学   311篇
物理学   249篇
  2022年   17篇
  2021年   23篇
  2020年   15篇
  2019年   19篇
  2018年   19篇
  2017年   21篇
  2016年   38篇
  2015年   20篇
  2014年   44篇
  2013年   80篇
  2012年   80篇
  2011年   76篇
  2010年   59篇
  2009年   68篇
  2008年   87篇
  2007年   111篇
  2006年   102篇
  2005年   86篇
  2004年   78篇
  2003年   59篇
  2002年   48篇
  2001年   33篇
  2000年   23篇
  1999年   20篇
  1998年   20篇
  1997年   22篇
  1996年   33篇
  1995年   24篇
  1994年   22篇
  1993年   23篇
  1992年   19篇
  1991年   16篇
  1990年   21篇
  1989年   15篇
  1988年   17篇
  1987年   14篇
  1986年   15篇
  1985年   23篇
  1984年   19篇
  1983年   13篇
  1982年   24篇
  1981年   12篇
  1980年   15篇
  1979年   8篇
  1978年   13篇
  1977年   18篇
  1976年   10篇
  1975年   6篇
  1974年   8篇
  1965年   8篇
排序方式: 共有1699条查询结果,搜索用时 15 毫秒
11.
Our purpose in the paper is to find the most general linear congruence relation of the Hardy-Williams type for linear combinations of special values of Kubota-Leopoldt 2-adic L-functions L2(k,χω1−k) with k running over any finite subset of not necessarily consisting of consecutive integers (see Acta Arith. 47 (1986) 263; Publ. Math. Fac. Sci. Besançon, Théorie des Nombres, 1995/1996; Publ. Math. Debrecen 56 (2000) 677 and cf. Mathematics and Its Applications, Vol. 511, Kluwer Academic Publishers, Dordrecht, Boston, London, 2000). If k runs over finite subsets of consisting of consecutive integers see Compositio Math. 111 (1998) 289; Publ. Math. Debrecen 56 (2000) 677; Hardy and Williams, 1986; Compositio Math. 75 (1990) 271; Acta Arith. 71 (1995) 273; 52 (1989) 147; J. Number Theory 34 (1990) 362. In order to obtain the most general congruences of this type we make use of divisibility properties of the generalized Vandermonde determinants obtained in Spie? et al. (Divisibility properties of generalized Vandermonde and Cauchy determinants, Preprint 627, Institute of Mathematics, Polish Academy of Sciences, Warsaw, 2002). This allows us to simplify our main Theorem 2 and obtain Theorem 3 where the most general form of the linear congruence relation is given.  相似文献   
12.
13.
An ab initio classical trajectories obtained from the simulation of vibrational mode dynamics of H3+ molecule were analyzed by Fourier transform and recurrence plot analysis. As has been found, at a particular value of energy supplied to vibrational modes (slightly above the zero point energy) the character of vibrational motion changes from regular to chaotic.  相似文献   
14.
Local convergence of quasi-Newton methods for B-differentiable equations   总被引:7,自引:0,他引:7  
We study local convergence of quasi-Newton methods for solving systems of nonlinear equations defined by B-differentiable functions. We extend the classical linear and superlinear convergence results for general quasi-Newton methods as well as for Broyden's method. We also show how Broyden's method may be applied to nonlinear complementarity problems and illustrate its computational performance on two small examples.  相似文献   
15.
This paper presents a comparative study of the use of two different methods of data analysis on a common set of data. The first is a method based on rough sets theory and the second is the location model method from the field of discriminant analysis. To investigate the comparative performance of these methods, a set of real medical data has been used. The data considered are of both discrete and continuous character. During the comparison, particular attention is paid to data reduction and to the derivation of decision rules and classification functions from the reduced set.  相似文献   
16.
In this article, a way to employ the diffusion approximation to model interplay between TCP and UDP flows is presented. In order to control traffic congestion, an environment of IP routers applying AQM (Active Queue Management) algorithms has been introduced. Furthermore, the impact of the fractional controller PIγ and its parameters on the transport protocols is investigated. The controller has been elaborated in accordance with the control theory. The TCP and UDP flows are transmitted simultaneously and are mutually independent. Only the TCP is controlled by the AQM algorithm. Our diffusion model allows a single TCP or UDP flow to start or end at any time, which distinguishes it from those previously described in the literature.  相似文献   
17.
Quantum ring accommodating interacting spin-less fermions threaded by magnetic flux with a non-classical component added to a static, inducing persistent current, is considered. It is investigated how current flowing in the ring becomes affected by a state of non-classical flux and how Coulomb interaction between fermions influences entanglement of quantum ring and the driving field. In particular it is shown that in an absence of decoherence and under certain conditions fermion–fermion interaction is necessary for a ring–field entanglement to occur.  相似文献   
18.
Discrete difference equations in Minkowski space are obtained and the discrete Minkowski force is shown to be a four-vector. A transformation from a discrete dynamical equation in Minkowski space to a Lorentz-invariant difference equation in one-dimensional space is given.  相似文献   
19.
We prove that certain two-point Padé approximants occupying the diagonal of the Padé table form monotone sequences of lower and upper bounds uniformly converging to a Stieltjes function. The results can be applied to the theory of inhomogeneous media for the calculation of the bounds on the effective transport coefficients of heterogeneous materials.  相似文献   
20.
In this paper we consider generalized convexity and concavity properties of the optimal value functionf * for the general parametric optimization problemP(ε) of the form min x f(x, ε) s.t.x∈R(ε). Many results on convexity and concavity characterizations off * were presented by the authors in a previous paper. Such properties off * and the solution set mapS * form an important part of the theoretical basis for sensitivity, stability and parametric analysis in mathematical optimization. We give sufficient conditions for several types of generalized convexity and concavity off *, in terms of respective generalized convexity and concavity assumptions onf and convexity and concavity assumptions on the feasible region point-to-set mapR. Specializations of these results to the parametric inequality-equality constrained nonlinear programming problem are provided. Research supported by Grant ECS-8619859, National Science Foundation and Contract N00014-86-K-0052, Office of Naval Research.  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