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   4888篇
  免费   380篇
  国内免费   565篇
化学   97篇
晶体学   1篇
力学   249篇
综合类   82篇
数学   4408篇
物理学   996篇
  2024年   8篇
  2023年   39篇
  2022年   52篇
  2021年   69篇
  2020年   100篇
  2019年   111篇
  2018年   118篇
  2017年   119篇
  2016年   131篇
  2015年   95篇
  2014年   229篇
  2013年   363篇
  2012年   161篇
  2011年   216篇
  2010年   215篇
  2009年   301篇
  2008年   383篇
  2007年   346篇
  2006年   329篇
  2005年   254篇
  2004年   219篇
  2003年   283篇
  2002年   250篇
  2001年   214篇
  2000年   204篇
  1999年   167篇
  1998年   161篇
  1997年   134篇
  1996年   101篇
  1995年   55篇
  1994年   60篇
  1993年   35篇
  1992年   29篇
  1991年   31篇
  1990年   22篇
  1989年   14篇
  1988年   23篇
  1987年   14篇
  1986年   15篇
  1985年   25篇
  1984年   18篇
  1983年   14篇
  1982年   19篇
  1981年   13篇
  1980年   12篇
  1979年   13篇
  1978年   12篇
  1977年   7篇
  1976年   11篇
  1975年   8篇
排序方式: 共有5833条查询结果,搜索用时 15 毫秒
51.
关于群体决策的偏比映射   总被引:5,自引:0,他引:5  
本文引进群体决策的决策个体和决策群体关于供选方案对的偏比度,以及偏比泛函概念.由此,定义了群体在供选方案集上的偏比映射,构造了相应的偏比公理系,并且建立了关于群体决策的偏比度分析的基本理论.最后,给出一个利用偏比映射进行群体排序的方法.特别是,文中表明,满足本文所提出的所有偏比公理的偏比映射是存在的.  相似文献   
52.
In this paper we investigate the probabilistic linear $(n,\delta)$-widths and $p$-average linear $n$-widths of the Sobolev space $W^r_2$ equipped with the Gaussian measure $\mu$ in the $L_{\infty}$-norm, and determine the asymptotic equalities \begin{eqnarray*} \lambda_{n,\delta}(W^r_2,\mu,L_{\infty}) &\asymp&\frac{\sqrt{\ln (n/\delta)}}{n^{r+(s-1)/2}},\\[3pt] \lambda^{(a)}_n(W^r_2,\mu,L_{\infty})_p &\asymp&\frac{\sqrt{\ln n}}{n^{r+(s-1)/2}}, \qquad 0 < p < \infty. \end{eqnarray*}  相似文献   
53.
By combining the Kramers-Moyal expansion with fractional Brownian motion of order n, in a formal symbolic calculus, one can obtain an approximation for the solution of some stochastic differential equations involving both Gaussian and Poissonian white noises, in terms of rotating Gaussian white noises on the grid defined by the complex roots of the unity. Illustrative examples are outlined.  相似文献   
54.
We study the attractors of a finite system of planar contraction similarities S j (j=1,...,n) satisfying the coupling condition: for a set {x 0,...,x n} of points and a binary vector (s 1,...,s n ), called the signature, the mapping S j takes the pair {x 0,x n} either into the pair {x j-1,x j } (if s j =0) or into the pair {x j , x j-1} (if s j =1). We describe the situations in which the Jordan property of such attractor implies that the attractor has bounded turning, i.e., is a quasiconformal image of an interval of the real axis.  相似文献   
55.
Parabolic Capacity and Soft Measures for Nonlinear Equations   总被引:2,自引:0,他引:2  
We first introduce, using a functional approach, the notion of capacity related to the parabolic p-Laplace operator. Then we prove a decomposition theorem for measures (in space and time) that do not charge the sets of null capacity. We apply this result to prove existence and uniqueness of renormalized solutions for nonlinear parabolic initial boundary-value problems with such measures as right-hand side.  相似文献   
56.
Aliev  R. A. 《Mathematical Notes》2003,73(1-2):8-20
Suppose that is an arbitrary finite complex Borel measure on the interval is its Poisson integral, and are the conjugate harmonics of , and is the nontangential limiting value of the analytic function as . In this paper, we consider the problem of representing the analytic function in terms of its boundary values .  相似文献   
57.
A symmetric operator X^ is attached to each operator X that leaves the domain of a given positive operator A invariant and makes the product AX symmetric. Some spectral properties of X^ are derived from those of X and, as a consequence, various conditions ensuring positivity of products of the form AX 1 ... X n are proved. The question of ^-complete positivity of the mapping pAp(X 1,...,X n) defined on complex polynomials in n variables is investigated. It is shown that the set ω is related to the McIntosh-Pryde joint spectrum of (X 1,...,X n) in case all the operators A, X 1,...,X n are bounded. Examples illustrating the theme of the paper are included. This revised version was published online in June 2006 with corrections to the Cover Date.  相似文献   
58.
In this paper, we derive an explicit group-invariant formula for the Euler–Lagrange equations associated with an invariant variational problem. The method relies on a group-invariant version of the variational bicomplex induced by a general equivariant moving frame construction, and is of independent interest.  相似文献   
59.
The aim of this paper is to prove some fixed point theorems which generalize well known basic fixed point principles of nonlinear functional analysis. Moreover, we investigate the class of mappings f: X→ X, where X is a Banach space, for which one of the main conditions in the metric fixed point theory, namely the condition (1), is satisfied. We obtain essential applications of this fact. All our results are illustrated by suitable examples. This revised version was published online in June 2006 with corrections to the Cover Date.  相似文献   
60.
Janssen  K. 《Potential Analysis》2003,19(3):289-299
We show that functions which are invariant for suitable product semigroups (one of which is a quasi-Poisson semigroup on a general state space) decompose into a singular eigen-function and a mixture of products of minimal eigen-functions.  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