全文获取类型
收费全文 | 16274篇 |
免费 | 1345篇 |
国内免费 | 788篇 |
专业分类
化学 | 302篇 |
晶体学 | 8篇 |
力学 | 2241篇 |
综合类 | 111篇 |
数学 | 12794篇 |
物理学 | 2951篇 |
出版年
2024年 | 33篇 |
2023年 | 172篇 |
2022年 | 111篇 |
2021年 | 238篇 |
2020年 | 454篇 |
2019年 | 443篇 |
2018年 | 448篇 |
2017年 | 432篇 |
2016年 | 417篇 |
2015年 | 384篇 |
2014年 | 678篇 |
2013年 | 1782篇 |
2012年 | 634篇 |
2011年 | 946篇 |
2010年 | 773篇 |
2009年 | 1069篇 |
2008年 | 1048篇 |
2007年 | 964篇 |
2006年 | 886篇 |
2005年 | 681篇 |
2004年 | 621篇 |
2003年 | 614篇 |
2002年 | 605篇 |
2001年 | 484篇 |
2000年 | 489篇 |
1999年 | 445篇 |
1998年 | 371篇 |
1997年 | 351篇 |
1996年 | 263篇 |
1995年 | 181篇 |
1994年 | 168篇 |
1993年 | 140篇 |
1992年 | 103篇 |
1991年 | 93篇 |
1990年 | 79篇 |
1989年 | 60篇 |
1988年 | 46篇 |
1987年 | 49篇 |
1986年 | 37篇 |
1985年 | 64篇 |
1984年 | 104篇 |
1983年 | 50篇 |
1982年 | 64篇 |
1981年 | 64篇 |
1980年 | 58篇 |
1979年 | 56篇 |
1978年 | 54篇 |
1977年 | 33篇 |
1976年 | 27篇 |
1974年 | 7篇 |
排序方式: 共有10000条查询结果,搜索用时 625 毫秒
71.
Identification of nonlinear elliptic equations 总被引:1,自引:0,他引:1
An optimization theoretic approach and algorithm for the estimation of state-dependent coefficients in nonlinear elliptic equation is presented. It is based on a splitting method combined with convex analysis techniques. Convergence of the algorithm is established and numerical examples are included.The research of K. Kunisch was supported in part by a grant from the Bundesministerium für Wissenschaft und Forschung, Austria. 相似文献
72.
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
73.
A. S. Kholodov Ya. A. Kholodov 《Computational Mathematics and Mathematical Physics》2006,46(9):1560-1588
Previously formulated monotonicity criteria for explicit two-level difference schemes designed for hyperbolic equations (S.K. Godunov’s, A. Harten’s (TVD schemes), characteristic criteria) are extended to multileveled, including implicit, stencils. The characteristic monotonicity criterion is used to develop a universal algorithm for constructing high-order accurate nonlinear monotone schemes (for an arbitrary form of the desired solution) based on their analysis in the space of grid functions. Several new fourth-to-third-order accurate monotone difference schemes on a compact three-level stencil and nonexpanding (three-point) stencils are proposed for an extended system, which ensures their monotonicity for both the desired function and its derivatives. The difference schemes are tested using the characteristic monotonicity criterion and are extended to systems of hyperbolic equations. 相似文献
74.
L. E. Payne G. A. Philippin V. Proytcheva 《Mathematical Methods in the Applied Sciences》2007,30(15):1885-1898
In this paper, we investigate the continuous dependence on the geometry and the initial time for solutions u( x , t) of a class of nonlinear parabolic initial‐boundary value problems. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
75.
Yang Zuosheng 《国际流体数值方法杂志》2005,47(12):1423-1430
A complete boundary integral formulation for compressible Navier–Stokes equations with time discretization by operator splitting is developed using the fundamental solutions of the Helmholtz operator equation with different order. The numerical results for wall pressure and wall skin friction of two‐dimensional compressible laminar viscous flow around airfoils are in good agreement with field numerical methods. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
76.
We demonstrate that a pair of additive quintic equations in at least 34 variables has a nontrivial integral solution, subject only to an 11-adic solubility hypothesis. This is achieved by an application of the Hardy–Littlewood method, for which we require a sharp estimate for a 33.998th moment of quintic exponential sums. We are able to employ p-adic iteration in a form that allows the estimation of such a mean value over a complete unit square, thereby providing an approach that is technically simpler than those of previous workers and flexible enough to be applied to related problems. 相似文献
77.
Dirichlet boundary value problems for perturbed second-order differential equations on a half line are investigated in this paper. The methods mainly depend on the calculus of variations to the classical functionals. Sufficient conditions are obtained for the existence of the solutions. 相似文献
78.
Kiyoshi Mochizuki 《Journal of Mathematical Analysis and Applications》2007,326(1):582-588
We show that the energy of solutions to the initial boundary value problem for the wave equation in exterior domains with a dissipation which is localized only near infinity tends to zero as the time goes to infinity. We do not make any geometrical condition like star-shapedness on the boundary. 相似文献
79.
Based on the theory of calculus of variation, some suffcient conditions are given for some Euler-Lagrangcequations to be equivalently represented by finite or even infinite many Hamiltonian canonical equations. Meanwhile,some further applications for equations such as the KdV equation, MKdV equation, the general linear Euler Lagrangeequation and the cylindric shell equations are given. 相似文献
80.
S. P. Popov 《Computational Mathematics and Mathematical Physics》2006,46(6):983-994
Numerical solutions to three systems of integrable evolutionary equations from the Toda lattice hierarchy are analyzed. These are the classical Toda lattice, the second local dispersive flow, and the second extended dispersive flow. Special attention is given to the properties of soliton solutions. For the equations of the second local flow, two types of solitons interacting in a special manner are found. Solutions corresponding to various initial data are qualitatively outlined. 相似文献