全文获取类型
收费全文 | 11867篇 |
免费 | 770篇 |
国内免费 | 827篇 |
专业分类
化学 | 737篇 |
晶体学 | 25篇 |
力学 | 806篇 |
综合类 | 189篇 |
数学 | 10586篇 |
物理学 | 1121篇 |
出版年
2024年 | 16篇 |
2023年 | 96篇 |
2022年 | 150篇 |
2021年 | 199篇 |
2020年 | 216篇 |
2019年 | 252篇 |
2018年 | 237篇 |
2017年 | 318篇 |
2016年 | 328篇 |
2015年 | 232篇 |
2014年 | 475篇 |
2013年 | 928篇 |
2012年 | 504篇 |
2011年 | 623篇 |
2010年 | 551篇 |
2009年 | 730篇 |
2008年 | 795篇 |
2007年 | 815篇 |
2006年 | 659篇 |
2005年 | 576篇 |
2004年 | 507篇 |
2003年 | 478篇 |
2002年 | 442篇 |
2001年 | 381篇 |
2000年 | 369篇 |
1999年 | 302篇 |
1998年 | 358篇 |
1997年 | 279篇 |
1996年 | 228篇 |
1995年 | 169篇 |
1994年 | 161篇 |
1993年 | 118篇 |
1992年 | 101篇 |
1991年 | 84篇 |
1990年 | 82篇 |
1989年 | 54篇 |
1988年 | 63篇 |
1987年 | 61篇 |
1986年 | 57篇 |
1985年 | 60篇 |
1984年 | 53篇 |
1983年 | 42篇 |
1982年 | 46篇 |
1981年 | 48篇 |
1980年 | 54篇 |
1979年 | 51篇 |
1978年 | 32篇 |
1977年 | 29篇 |
1976年 | 33篇 |
1974年 | 7篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
41.
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
42.
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
43.
We prove that for any given c, 1 < c < 17/11, almost all natural numbers are representable in the form [x
c] + [p
c], where x is a natural number and p is a prime. 相似文献
44.
In this paper, we use parametric quintic splines to derive some consistency relations which are then used to develop a numerical method for computing the solution of a system of fourth-order boundary-value problems associated with obstacle, unilateral, and contact problems. It is known that a class of variational inequalities related to contact problems in elastostatics can be characterized by a sequence of variational inequations, which are solved using some numerical method. Numerical evidence is presented to show the applicability and superiority of the new method over other collocation, finite difference, and spline methods. 相似文献
45.
Banach空间二阶周期边值问题解的存在性 总被引:2,自引:0,他引:2
利用一些比较结果,讨论了Banach空间中二阶周期边值问题解的存在性,获得了若干解的存在性与唯一性结果。 相似文献
46.
María G. Armentano Ricardo G. Durn 《Numerical Methods for Partial Differential Equations》2003,19(5):653-664
In this article we analyze the effect of mass‐lumping in the linear triangular finite element approximation of second‐order elliptic eigenvalue problems. We prove that the eigenvalue obtained by using mass‐lumping is always below the one obtained with exact integration. For singular eigenfunctions, as those arising in non convex polygons, we prove that the eigenvalue obtained with mass‐lumping is above the exact eigenvalue when the mesh size is small enough. So, we conclude that the use of mass‐lumping is convenient in the singular case. When the eigenfunction is smooth several numerical experiments suggest that the eigenvalue computed with mass‐lumping is below the exact one if the mesh is not too coarse. © 2003 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 19: 653–664, 2003 相似文献
47.
Xian Xu 《Journal of Mathematical Analysis and Applications》2004,291(2):673-689
In this paper, some multiplicity results for positive solutions of some singular semi-positone three-point boundary value problem be obtained by using the fixed point index method. 相似文献
48.
Zhimin He 《Journal of Mathematical Analysis and Applications》2004,296(1):97-109
In this paper, by means of a new twin fixed-point theorem in a cone, the existence of at least two positive solutions of m-point boundary value problem for second order dynamic equations on time scales is considered. 相似文献
49.
Adrian Doicu Franz Schreier Michael Hess 《Journal of Quantitative Spectroscopy & Radiative Transfer》2004,83(1):47-61
In this paper we present different inversion algorithms for nonlinear ill-posed problems arising in atmosphere remote sensing. The proposed methods are Landweber's method (LwM), the iteratively regularized Gauss-Newton method, and the conventional and regularizing Levenberg-Marquardt method. In addition, some accelerated LwMs and a technique for smoothing the Levenberg-Marquardt solution are proposed. The numerical performance of the methods is studied by means of simulations. Results are presented for an inverse problem in atmospheric remote sensing, i.e., temperature sounding with an airborne uplooking high-resolution far-infrared spectrometer. 相似文献
50.
Summary Our purpose is to extend results due to P. Chandra and L. Leindler concerning the order of approximation by means of Fourier series for functions belonging to generalized Lipschitz-classes. 相似文献