全文获取类型
收费全文 | 5894篇 |
免费 | 274篇 |
国内免费 | 258篇 |
专业分类
化学 | 69篇 |
力学 | 447篇 |
综合类 | 41篇 |
数学 | 5535篇 |
物理学 | 334篇 |
出版年
2023年 | 52篇 |
2022年 | 41篇 |
2021年 | 54篇 |
2020年 | 103篇 |
2019年 | 116篇 |
2018年 | 115篇 |
2017年 | 127篇 |
2016年 | 127篇 |
2015年 | 113篇 |
2014年 | 185篇 |
2013年 | 527篇 |
2012年 | 216篇 |
2011年 | 261篇 |
2010年 | 218篇 |
2009年 | 354篇 |
2008年 | 386篇 |
2007年 | 388篇 |
2006年 | 293篇 |
2005年 | 268篇 |
2004年 | 202篇 |
2003年 | 215篇 |
2002年 | 191篇 |
2001年 | 176篇 |
2000年 | 174篇 |
1999年 | 147篇 |
1998年 | 189篇 |
1997年 | 147篇 |
1996年 | 109篇 |
1995年 | 81篇 |
1994年 | 88篇 |
1993年 | 75篇 |
1992年 | 69篇 |
1991年 | 44篇 |
1990年 | 45篇 |
1989年 | 36篇 |
1988年 | 42篇 |
1987年 | 41篇 |
1986年 | 47篇 |
1985年 | 43篇 |
1984年 | 41篇 |
1983年 | 24篇 |
1982年 | 34篇 |
1981年 | 30篇 |
1980年 | 44篇 |
1979年 | 39篇 |
1978年 | 28篇 |
1977年 | 26篇 |
1976年 | 33篇 |
1975年 | 6篇 |
1974年 | 7篇 |
排序方式: 共有6426条查询结果,搜索用时 31 毫秒
31.
In this paper, we present a unified treatment and analysis of a dynamic traffic network model with elastic demands formulated and studied as a projected dynamical system. We propose a travel route choice adjustment process that satisfies the projected dynamical system. Under certain conditions, stability and asymptotical stability of the equilibrium patterns are then derived. Finally, two discrete-time algorithms, the Euler method and the Heun method, are proposed for the computation of the solutions, and convergence results established. The convergence results depend crucially on stability analysis. The performance of the algorithms is then illustrated on several transportation networks. 相似文献
32.
沈惠川 《数学物理学报(A辑)》1998,18(1):78-88
将弹性有限变形问题纳入Lagrange力学的理论体系中,并用经典力学中业已存在的Routh方法构建了有限变形平面应变问题和有限变形平面应力问题的基本微分方程,讨论了有限变形大挠度问题vonkarman方程中存在的矛盾进而提出了两种改进方案. 相似文献
33.
In this work two non-local problems for the parabolic-hyperbolic type equation with non-characteristic line of changing type
are considered. Unique solvability of these problems is proven. The uniqueness of the solution is proven by the method of
energy integrals and the existence is proven by the method of integral equations. 相似文献
34.
Kai-li Xiang 《计算数学(英文版)》2002,(2)
1. IntroductionWe consider a class of direct hybrid methods proposed in [11 for solving the second orderinitial value problemy" = f(t,y), y(0),y'(0) given (1.1)The basic method has the formandHere t. = nh and we define t.l.. = t. I aih, i = 1, 2 and n=0,1… 相似文献
35.
Silvia Vogel 《Annals of Operations Research》2006,142(1):269-282
The paper considers upper semicontinuous behavior in distribution of sequences of random closed sets. Semiconvergence in distribution
will be described via convergence in distribution of random variables with values in a suitable topological space. Convergence
statements for suitable functions of random sets are proved and the results are employed to derive stability statements for
random optimization problems where the objective function and the constraint set are approximated simultaneously.
The author is grateful to two anonymous referees for helpful suggestions. 相似文献
36.
Jian‐guo Tang 《Mathematical Methods in the Applied Sciences》2006,29(11):1327-1338
An implicit iterative method is applied to solving linear ill‐posed problems with perturbed operators. It is proved that the optimal convergence rate can be obtained after choosing suitable number of iterations. A generalized Morozov's discrepancy principle is proposed for the problems, and then the optimal convergence rate can also be obtained by an a posteriori strategy. The convergence results show that the algorithm is a robust regularization method. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
37.
High even order generalizations of the traditional upwind method are introduced to solve second order ODE-BVPs without recasting
the problem as a first order system. Both theoretical analysis and numerical comparison with central difference schemes of
the same order show that these new methods may avoid typical oscillations and achieve high accuracy. Singular perturbation
problems are taken into account to emphasize the main features of the proposed methods.
AMS subject classification (2000) 65L10, 65L12, 65L50 相似文献
38.
Zheng-su Wan Ben-yu Guo Zhong-qing Wang 《计算数学(英文版)》2006,24(4):481-500
In this paper, we investigate Jacobi pseudospectral method for fourth order problems. We establish some basic results on the Jacobi-Gauss-type interpolations in non-uniformly weighted Sobolev spaces, which serve as important tools in analysis of numerical quadratures, and numerical methods of differential and integral equations. Then we propose Jacobi pseudospectral schemes for several singular problems and multiple-dimensional problems of fourth order. Numerical results demonstrate the spectral accuracy of these schemes, and coincide well with theoretical analysis. 相似文献
39.
Zuo-liang Xu 《应用数学学报(英文版)》2007,23(4):629-636
In this paper,we study mixed elastico-plasticity problems in which part of the boundary is known,while the other part of the boundary is unknown and is a free boundary.Under certain conditions,this problemcan be transformed into a Riemann-Hilbert boundary value problem for analytic functions and a mixed boundaryvalue problem for complex equations.Using the theory of generalized analytic functions,the solvability of theproblem is discussed. 相似文献
40.
A nonclassical problem is considered for the transport equation with coefficients depending on the energy of radiation. The task is to find the discontinuity surfaces for the coefficients of the equation from measurements of the radiation flux leaving the medium. For this tomography problem, an optimization problem is stated and numerically analyzed. The latter consists in determining the radiation energy that ensures the best reconstruction of the unknown medium. A simplified optimization problem is solved analytically. 相似文献