全文获取类型
收费全文 | 14471篇 |
免费 | 954篇 |
国内免费 | 816篇 |
专业分类
化学 | 211篇 |
晶体学 | 2篇 |
力学 | 1447篇 |
综合类 | 166篇 |
数学 | 13310篇 |
物理学 | 1105篇 |
出版年
2024年 | 30篇 |
2023年 | 140篇 |
2022年 | 181篇 |
2021年 | 203篇 |
2020年 | 321篇 |
2019年 | 329篇 |
2018年 | 378篇 |
2017年 | 386篇 |
2016年 | 372篇 |
2015年 | 274篇 |
2014年 | 608篇 |
2013年 | 1149篇 |
2012年 | 650篇 |
2011年 | 764篇 |
2010年 | 679篇 |
2009年 | 939篇 |
2008年 | 987篇 |
2007年 | 1020篇 |
2006年 | 897篇 |
2005年 | 696篇 |
2004年 | 599篇 |
2003年 | 667篇 |
2002年 | 573篇 |
2001年 | 432篇 |
2000年 | 442篇 |
1999年 | 393篇 |
1998年 | 364篇 |
1997年 | 323篇 |
1996年 | 248篇 |
1995年 | 204篇 |
1994年 | 138篇 |
1993年 | 119篇 |
1992年 | 119篇 |
1991年 | 104篇 |
1990年 | 79篇 |
1989年 | 38篇 |
1988年 | 41篇 |
1987年 | 38篇 |
1986年 | 41篇 |
1985年 | 54篇 |
1984年 | 53篇 |
1983年 | 28篇 |
1982年 | 28篇 |
1981年 | 25篇 |
1980年 | 18篇 |
1979年 | 21篇 |
1978年 | 14篇 |
1977年 | 15篇 |
1976年 | 9篇 |
1936年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
131.
We investigate the six-dimensional Schrödinger equation for a three-body system with central pair interactions of a more general form than Coulomb interactions. Regular general and special physical solutions of this equation are represented by infinite asymptotic series in integer powers of the distance between two particles and in the sought functions of the other three-body coordinates. Constructing such functions in angular bases composed of spherical and bispherical harmonics or symmetrized Wigner D-functions is reduced to solving simple recursive algebraic equations. For projections of physical solutions on the angular bases functions, we derive boundary conditions at the pair impact point. 相似文献
132.
J. Haslinger T. Kozubek K. Kunisch G. Peichl 《Journal of Mathematical Analysis and Applications》2004,290(2):665-685
This contribution combines a shape optimization approach to free boundary value problems of Bernoulli type with an embedding domain technique. A theoretical framework is developed which allows to prove continuous dependence of the primal and dual variables in the resulting saddle point problems with respect to the domain. This ensures the existence of a solution of a related shape optimization problem in a sufficiently large class of admissible domains. 相似文献
133.
Grundel D. A. Oliveira C. A. S. Pardalos P. M. 《Journal of Optimization Theory and Applications》2004,122(3):487-500
The multidimensional assignment problem (MAP) is a NP-hard combinatorial optimization problem, occurring in many applications, such as data association. In this paper, we prove two conjectures made in Ref. 1 and based on data from computational experiments on MAPs. We show that the mean optimal objective function cost of random instances of the MAP goes to zero as the problem size increases, when assignment costs are independent exponentially or uniformly distributed random variables. We prove also that the mean optimal solution goes to negative infinity when assignment costs are independent normally distributed random variables. 相似文献
134.
A fourth‐order compact finite difference scheme on the nine‐point 2D stencil is formulated for solving the steady‐state Navier–Stokes/Boussinesq equations for two‐dimensional, incompressible fluid flow and heat transfer using the stream function–vorticity formulation. The main feature of the new fourth‐order compact scheme is that it allows point‐successive overrelaxation (SOR) or point‐successive underrelaxation iteration for all Rayleigh numbers Ra of physical interest and all Prandtl numbers Pr attempted. Numerical solutions are obtained for the model problem of natural convection in a square cavity with benchmark solutions and compared with some of the accurate results available in the literature. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
135.
In this paper we consider an obstacle control problem where the state satisfies a quasilinear elliptic variational inequality and the control function is the obstacle. The state is chosen to be close to the desire profile while the H2 norms of the obstacle is not too large. Existence and necessary conditions for the optimal control are established. 相似文献
136.
The paper deals with a singularly perturbed reaction diffusionmodel problem. The focus is on reliable a posteriori error estimatorsfor the H1 seminorm that can be applied to anisotropic finiteelement meshes. A residual error estimator and a local problemerror estimator are proposed and rigorously analysed. They arelocally equivalent, and both bound the error reliably. Threemodifications of these estimators are introduced and discussed. Much attention is given to the performance of the error estimatorin numerical experiments. This helps to identify those estimatorsthat are suitable for practical applications. 相似文献
137.
138.
Vincenzo Recupero 《Journal of Mathematical Analysis and Applications》2004,300(2):387-407
In this paper we study a model of phase relaxation for the Stefan problem with the Cattaneo–Maxwell heat flux law. We prove an existence and uniqueness result for the resulting problem and we show that its solution converges to the solution of the Stefan problem as the two relaxation parameters go to zero, provided a relation between these parameters holds. 相似文献
139.
Rinaldo M. Colombo Alessandro Groli 《Journal of Mathematical Analysis and Applications》2004,291(1):82-99
In the present note, the theory of shift differentiability for the Cauchy problem is extended to the case of an initial boundary value problem for a conservation law. This result allows to exhibit an Euler-Lagrange equation to be satisfied by the extrema of integral functionals defined on the solutions of initial boundary value problems of this kind. 相似文献
140.
Tie-Jun Liu Yue-Sheng Wang Chuanzeng Zhang 《Archive of Applied Mechanics (Ingenieur Archiv)》2008,78(4):267-282
The main interest of this study is a new method to solve the axisymmetric frictionless contact problem of functionally graded
materials (FGMs). Based on the fact that an arbitrary curve can be approached by a series of continuous but piecewise linear
curves, the FGM is divided into a series of sub-layers with shear modulus varying linearly in each sub-layer and continuous
at the sub-interfaces. With this model, the axisymmetric frictionless contact problem of a functionally graded coated half-space
is investigated. By using the transfer matrix method and Hankel integral transform technique, the problem is reduced to a
Cauchy singular integral equation. The contact pressure, contact region and indentation are calculated for various indenters
by solving the equations numerically.
An erratum to this article can be found at 相似文献