全文获取类型
收费全文 | 6794篇 |
免费 | 516篇 |
国内免费 | 500篇 |
专业分类
化学 | 114篇 |
力学 | 269篇 |
综合类 | 155篇 |
数学 | 6368篇 |
物理学 | 203篇 |
无线电 | 701篇 |
出版年
2024年 | 7篇 |
2023年 | 67篇 |
2022年 | 63篇 |
2021年 | 121篇 |
2020年 | 175篇 |
2019年 | 164篇 |
2018年 | 157篇 |
2017年 | 182篇 |
2016年 | 190篇 |
2015年 | 148篇 |
2014年 | 287篇 |
2013年 | 524篇 |
2012年 | 338篇 |
2011年 | 378篇 |
2010年 | 323篇 |
2009年 | 422篇 |
2008年 | 386篇 |
2007年 | 426篇 |
2006年 | 373篇 |
2005年 | 315篇 |
2004年 | 268篇 |
2003年 | 243篇 |
2002年 | 270篇 |
2001年 | 267篇 |
2000年 | 260篇 |
1999年 | 210篇 |
1998年 | 194篇 |
1997年 | 184篇 |
1996年 | 140篇 |
1995年 | 109篇 |
1994年 | 89篇 |
1993年 | 72篇 |
1992年 | 50篇 |
1991年 | 49篇 |
1990年 | 51篇 |
1989年 | 26篇 |
1988年 | 20篇 |
1987年 | 24篇 |
1986年 | 23篇 |
1985年 | 29篇 |
1984年 | 28篇 |
1983年 | 15篇 |
1982年 | 30篇 |
1981年 | 20篇 |
1980年 | 16篇 |
1979年 | 18篇 |
1978年 | 20篇 |
1977年 | 14篇 |
1976年 | 11篇 |
1974年 | 3篇 |
排序方式: 共有7810条查询结果,搜索用时 9 毫秒
191.
A subset of the -dimensional torus is called a set of uniqueness, or -set, if every multiple trigonometric series spherically converging to outside vanishes identically. We show that all countable sets are -sets and also that sets are -sets for every . In particular, , where is the Cantor set, is an set and hence a -set. We will say that is a -set if every multiple trigonometric series spherically Abel summable to outside and having certain growth restrictions on its coefficients vanishes identically. The above-mentioned results hold also for sets. In addition, every -set has measure , and a countable union of closed -sets is a -set.
192.
An adaptive trust region method and its convergence 总被引:17,自引:0,他引:17
In this paper, a new trust region subproblem is proposed. The trust radius in the new subproblem adjusts itself adaptively.
As a result, an adaptive trust region method is constructed based on the new trust region subproblem. The local and global
convergence results of the adaptive trust region method are proved. Numerical results indicate that the new method is very
efficient. 相似文献
193.
对于复域中满足某种条件的Jordan区域D和函数f∈B(D),证明了基于Fejer点的高阶Fejer插值多项式一致收敛于对应的函数f(z)于D上.本文中的这些定理推广了某些已知的结果. 相似文献
194.
C. Gonzá lez A. Ostermann C. Palencia M. Thalhammer. 《Mathematics of Computation》2002,71(237):125-145
This paper is concerned with the time discretization of nonlinear evolution equations. We work in an abstract Banach space setting of analytic semigroups that covers fully nonlinear parabolic initial-boundary value problems with smooth coefficients. We prove convergence of variable stepsize backward Euler discretizations under various smoothness assumptions on the exact solution. We further show that the geometric properties near a hyperbolic equilibrium are well captured by the discretization. A numerical example is given.
195.
We present a new approach to study the convergence of Newton's method in Banach spaces, which relax the conditions appearing in the usual studies. The approach is based on the bound required for the second derivative of the operator involved. An application to a nonlinear integral equation is presented. 相似文献
196.
Globally and Superlinearly Convergent QP-Free Algorithm for Nonlinear Constrained Optimization 总被引:2,自引:0,他引:2
A new, infeasible QP-free algorithm for nonlinear constrained optimization problems is proposed. The algorithm is based on a continuously differentiable exact penalty function and on active-set strategy. After a finite number of iterations, the algorithm requires only the solution of two linear systems at each iteration. We prove that the algorithm is globally convergent toward the KKT points and that, if the second-order sufficiency condition and the strict complementarity condition hold, then the rate of convergence is superlinear or even quadratic. Moreover, we incorporate two automatic adjustment rules for the choice of the penalty parameter and make use of an approximated direction as derivative of the merit function so that only first-order derivatives of the objective and constraint functions are used. 相似文献
197.
A distribution function F on the nonnegative real line is called subexponential if limx(1-F
*n
(x)/(1 - F(x)) = n for all n 2, where F
*n
denotes the nfold Stieltjes convolution of F with itself. In this paper, we consider the rate of convergence in the above definition and in its density analogue. Among others we discuss the asymptotic behavior of the remainder term R
n
(x) defined by R
n
(x) = 1 - F*n(x) - n(1 - F(x)) and of its density analogue rn (x) = -(Rn (x))'. Our results complement and complete those obtained by several authors. In an earlier paper, we obtained results of the form n(x) = O(1)f(x)R(x), where f is the density of F and R(x) =
0
x
(1-F(y))dy. In this paper, among others we obtain asymptotic expressions of the form R
n(x)=
2
n
R2(x) + O(1)(-f'(x))R2(x) where f' is the derivative of f. 相似文献
198.
Tadeusz Jankowski 《Czechoslovak Mathematical Journal》2002,52(3):553-563
The method of quasilinearization is a well-known technique for obtaining approximate solutions of nonlinear differential equations. In this paper we apply this technique to functional differential problems. It is shown that linear iterations converge to the unique solution and this convergence is superlinear. 相似文献
199.
R-linear convergence of the Barzilai and Borwein gradient method 总被引:4,自引:0,他引:4
Combined with non-monotone line search, the Barzilai and Borwein(BB) gradient method has been successfully extended for solvingunconstrained optimization problems and is competitive withconjugate gradient methods. In this paper, we establish theR-linear convergence of the BB method for any-dimensional stronglyconvex quadratics. One corollary of this result is that theBB method is also locally R-linear convergent for general objectivefunctions, and hence the stepsize in the BB method will alwaysbe accepted by the non-monotone line search when the iterateis close to the solution. 相似文献
200.
This paper states and generalizes in part some recent results on finite difference methods for Dirichlet problems in a bounded domain Ω which the author has obtained by himself or with coworkers. After stating a superconvergence property of finite difference solution for the case where the exact solution u belongs to
, it is remarked that such a property does not hold in general if
. Next, a convergence theorem is given for inconsistent schemes under some assumptions. Furthermore, it is shown that the accuracy of the approximate solution can be improved by a coordinate transformation. Numerical examples are also given. 相似文献