全文获取类型
收费全文 | 19673篇 |
免费 | 1612篇 |
国内免费 | 952篇 |
专业分类
化学 | 652篇 |
晶体学 | 14篇 |
力学 | 2977篇 |
综合类 | 140篇 |
数学 | 14003篇 |
物理学 | 4451篇 |
出版年
2024年 | 35篇 |
2023年 | 196篇 |
2022年 | 149篇 |
2021年 | 302篇 |
2020年 | 529篇 |
2019年 | 513篇 |
2018年 | 517篇 |
2017年 | 501篇 |
2016年 | 513篇 |
2015年 | 499篇 |
2014年 | 830篇 |
2013年 | 2022篇 |
2012年 | 770篇 |
2011年 | 1091篇 |
2010年 | 885篇 |
2009年 | 1243篇 |
2008年 | 1245篇 |
2007年 | 1195篇 |
2006年 | 1074篇 |
2005年 | 827篇 |
2004年 | 759篇 |
2003年 | 757篇 |
2002年 | 734篇 |
2001年 | 613篇 |
2000年 | 655篇 |
1999年 | 564篇 |
1998年 | 475篇 |
1997年 | 442篇 |
1996年 | 320篇 |
1995年 | 233篇 |
1994年 | 213篇 |
1993年 | 191篇 |
1992年 | 141篇 |
1991年 | 125篇 |
1990年 | 98篇 |
1989年 | 76篇 |
1988年 | 70篇 |
1987年 | 72篇 |
1986年 | 52篇 |
1985年 | 75篇 |
1984年 | 110篇 |
1983年 | 54篇 |
1982年 | 72篇 |
1981年 | 74篇 |
1980年 | 64篇 |
1979年 | 69篇 |
1978年 | 56篇 |
1977年 | 41篇 |
1976年 | 29篇 |
1973年 | 18篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
181.
We consider the 3D Navier–Stokes equation with generalized impermeability boundary conditions. As auxiliary results, we prove the local in time existence of a strong solution (‘strong’ in a limited sense) and a theorem on structure. Then, taking advantage of the boundary conditions, we formulate sufficient conditions for regularity up to the boundary of a weak solution by means of requirements on one of the eigenvalues of the rate of deformation tensor. Finally, we apply these general results to the case of an axially symmetric flow with zero angular velocity. 相似文献
182.
By utilizing a fixed point theorem on cone,some new results on the existence of positive periodic solutions for nonautonomous differential equations with delay are derived. 相似文献
183.
Due to the Meissner effect, a permanent magnet is levitated, when released above a high temperature superconductor. When there is an inhomogeneous temperature field around the magnet, the magnet might start to oscillate with increasing amplitude until it remains in a continuous rotation. A mathematical model for the described effect is presented which couples heat transfer and electromagnetic forces with the equation of motion, yielding to a multiphysics task. In a detailed analysis it is found, that the torque which drives the rotation of the magnet, is explicitly given in terms of Bessel functions and the Fourier coefficients of order zero and one of the temperature field of the surrounding air. 相似文献
184.
We study the asymptotic behaviour of non-negative solutions of Yamabe type equations on a complete Riemannian manifold. Then we provide a comparison result, based on a form of the weak maximum principle at infinity, which together with the “a priori” estimates previously obtained, yields uniqueness under very general Ricci assumptions. The paper ends with an existence result and an application to the non-compact Yamabe problem. 相似文献
185.
Abstract In [16] a visco-elastic relaxation system, called the relaxed Burnett system, was proposed by Jinand Slemrod as a moment approximation to the Boltzmann equation. The relaxed Burnett system is weaklyparabolic, has a linearly hyperbolic convection part, and is endowed with a generalized eotropy inequality. Itagrees with the solution of the Boltzmann equation up to the Burnett order via the Chapman-Enskog expansion. We develop a one-dimensional non-oscillatory numerical scheme based on the relaxed Burnett system forthe Boltzmann equation. We compare numerical results for stationary shocks based on this relaxation scheme,and those obtained by the DSMC (Direct Simulation Monte Carlo), by the Navier-Stokes equations and bythe extended thermodynamics with thirteen moments (the Grad equations). Our numerical experiments showthat the relaxed Burnett gives more accurate approximations to the shock profiles of the Boltzmann equationobtained by the DSMC, for a range of Mach numbers for hypersonic flows, th 相似文献
186.
187.
188.
189.
In this paper we consider certain matrix equations in the field of Mikusiński operators, and construct a method for obtaining an approximate solution which allows working with numerical constants instead of operators. The theory of diagonally dominant matrices is applied for the analysis, existence and character of the obtained solutions. We introduce a method for determining approximate solutions of a discrete analogue for operational differential equations and give conditions for their existence. The error of the approximation is estimated. 相似文献
190.
Arne Barinka Stephan Dahlke Wolfgang Dahmen 《Advances in Computational Mathematics》2006,24(1-4):5-34
Recently adaptive wavelet methods have been developed which can be shown to exhibit an asymptotically optimal accuracy/work
balance for a wide class of variational problems including classical elliptic boundary value problems, boundary integral equations
as well as certain classes of noncoercive problems such as saddle point problems. A core ingredient of these schemes is the
approximate application of the involved operators in standard wavelet representation. Optimal computational complexity could
be shown under the assumption that the entries in properly compressed standard representations are known or computable in
average at unit cost. In this paper we propose concrete computational strategies and show under which circumstances this assumption
is justified in the context of elliptic boundary value problems.
Dedicated to Charles A. Micchelli on the occasion of his 60th birthday
Mathematics subject classifications (2000) 41A25, 41A46, 65F99, 65N12, 65N55.
This work has been supported in part by the Deutsche Forschungsgemeinschaft SFB 401, the first and third author are supported
in part by the European Community's Human Potential Programme under contract HPRN-CT-202-00286 (BREAKING COMPLEXITY). The
second author acknowledges the financial support provided through the European Union's Human Potential Programme, under contract
HPRN-CT-2002-00285 (HASSIP) and through DFG grant DA 360/4–1. 相似文献