全文获取类型
收费全文 | 5602篇 |
免费 | 450篇 |
国内免费 | 427篇 |
专业分类
化学 | 413篇 |
晶体学 | 19篇 |
力学 | 1083篇 |
综合类 | 88篇 |
数学 | 3658篇 |
物理学 | 1218篇 |
出版年
2023年 | 51篇 |
2022年 | 66篇 |
2021年 | 69篇 |
2020年 | 91篇 |
2019年 | 103篇 |
2018年 | 94篇 |
2017年 | 138篇 |
2016年 | 164篇 |
2015年 | 146篇 |
2014年 | 218篇 |
2013年 | 300篇 |
2012年 | 244篇 |
2011年 | 261篇 |
2010年 | 213篇 |
2009年 | 305篇 |
2008年 | 323篇 |
2007年 | 373篇 |
2006年 | 347篇 |
2005年 | 343篇 |
2004年 | 288篇 |
2003年 | 260篇 |
2002年 | 251篇 |
2001年 | 207篇 |
2000年 | 244篇 |
1999年 | 232篇 |
1998年 | 190篇 |
1997年 | 194篇 |
1996年 | 102篇 |
1995年 | 84篇 |
1994年 | 82篇 |
1993年 | 81篇 |
1992年 | 57篇 |
1991年 | 70篇 |
1990年 | 42篇 |
1989年 | 28篇 |
1988年 | 30篇 |
1987年 | 25篇 |
1986年 | 11篇 |
1985年 | 21篇 |
1984年 | 20篇 |
1983年 | 5篇 |
1982年 | 19篇 |
1981年 | 16篇 |
1980年 | 11篇 |
1979年 | 11篇 |
1978年 | 12篇 |
1977年 | 11篇 |
1976年 | 4篇 |
1974年 | 6篇 |
1957年 | 5篇 |
排序方式: 共有6479条查询结果,搜索用时 0 毫秒
1.
An attempt is made to find out the suitable entrainment and exit boundary conditions in laminar flow situations. Streamfunction vorticity formulation of the Navier–Stokes equations are solved by ADI method. Two‐dimensional laminar plane wall jet flow is used to test different forms of the boundary conditions. Results are compared with the experimental and similarity solution and the proper boundary condition is suggested. The Kind 1 boundary condition is recommended. It consists of zero first derivative condition for velocity variable and for streamfunction equation, mixed derivative at the entrainment and exit boundaries. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
2.
M. M. Kostreva 《Journal of Optimization Theory and Applications》1989,62(1):63-76
Murty's algorithm for the linear complementarity problem is generalized to solve the optimality conditions for linear and convex quadratic programming problems with both equality and inequality constraints. An implementation is suggested which provides both efficiency and tight error control. Numerical experiments as well as field tests in various applications show favorable results.The author thanks K. G. Murty for his encouragement and helpful comments. 相似文献
3.
4.
Stefan Nörtemann 《Applied Categorical Structures》2002,10(4):417-429
The Hahn–Banach Theorem for partially ordered totally convex modules [3] and a necessary and sufficient condition for the existence of an extension of a morphism from a submodule C
0 of a partially ordered totally convex module C (with the ordered unit ball of the reals as codomain) to C, are proved. Moreover, the categories of partially ordered positively convex and superconvex modules are introduced and for both categories the Hahn–Banach Theorem is proved. 相似文献
5.
线性分式规划最优解集的求法 总被引:5,自引:0,他引:5
薛声家 《应用数学与计算数学学报》2002,16(1):90-96
本文使用多面集的表示定理,导出了线性分式规划最优解集的结构,并给出确定全部最优解的计算步骤。 相似文献
6.
This paper gives some global and uniform convergence estimates for a class of subspace correction (based on space decomposition) iterative methods applied to some unconstrained convex optimization problems. Some multigrid and domain decomposition methods are also discussed as special examples for solving some nonlinear elliptic boundary value problems.
7.
The paper proposes a rational method to derive fairness measures for surfaces. It works in cases where isophotes, reflection lines, planar intersection curves, or other curves are used to judge the fairness of the surface. The surface fairness measure is derived by demanding that all the given curves should be fair with respect to an appropriate curve fairness measure. The method is applied to the field of ship hull design where the curves are plane intersections. The method is extended to the case where one considers, not the fairness of one curve, but the fairness of a one parameter family of curves. Six basic third order invariants by which the fairing measures can be expressed are defined. Furthermore, the geometry of a plane intersection curve is studied, and the variation of the total, the normal, and the geodesic curvature and the geodesic torsion is determined. 相似文献
8.
V. V. Kozlov 《Functional Analysis and Its Applications》2005,39(4):271-283
We discuss the symplectic geometry of linear Hamiltonian systems with nondegenerate Hamiltonians. These systems can be reduced to linear second-order differential equations characteristic of linear oscillation theory. This reduction is related to the problem on the signatures of restrictions of quadratic forms to Lagrangian planes. We study vortex symplectic planes invariant with respect to linear Hamiltonian systems. These planes are determined by the solutions of quadratic matrix equations of a special form. New conditions for gyroscopic stabilization are found. 相似文献
9.
L. Brian Lawrence 《Transactions of the American Mathematical Society》2005,357(7):2535-2556
Working in ZFC, we give an example as indicated in the title.
10.
Halszka TutajGasiska 《Mathematische Nachrichten》2003,257(1):108-116