全文获取类型
收费全文 | 1434篇 |
免费 | 20篇 |
国内免费 | 40篇 |
专业分类
化学 | 32篇 |
力学 | 33篇 |
综合类 | 3篇 |
数学 | 1355篇 |
物理学 | 71篇 |
出版年
2023年 | 13篇 |
2022年 | 19篇 |
2021年 | 23篇 |
2020年 | 20篇 |
2019年 | 17篇 |
2018年 | 23篇 |
2017年 | 12篇 |
2016年 | 12篇 |
2015年 | 15篇 |
2014年 | 44篇 |
2013年 | 110篇 |
2012年 | 105篇 |
2011年 | 51篇 |
2010年 | 40篇 |
2009年 | 88篇 |
2008年 | 98篇 |
2007年 | 65篇 |
2006年 | 59篇 |
2005年 | 54篇 |
2004年 | 44篇 |
2003年 | 26篇 |
2002年 | 43篇 |
2001年 | 31篇 |
2000年 | 31篇 |
1999年 | 30篇 |
1998年 | 29篇 |
1997年 | 25篇 |
1996年 | 30篇 |
1995年 | 25篇 |
1994年 | 23篇 |
1993年 | 11篇 |
1992年 | 14篇 |
1991年 | 6篇 |
1990年 | 6篇 |
1989年 | 4篇 |
1988年 | 3篇 |
1987年 | 5篇 |
1986年 | 23篇 |
1985年 | 28篇 |
1984年 | 27篇 |
1983年 | 19篇 |
1982年 | 28篇 |
1981年 | 16篇 |
1980年 | 31篇 |
1979年 | 24篇 |
1978年 | 32篇 |
1977年 | 5篇 |
1972年 | 2篇 |
1969年 | 2篇 |
1967年 | 1篇 |
排序方式: 共有1494条查询结果,搜索用时 207 毫秒
61.
M. L. Fisher 《Annals of Operations Research》1985,5(3):539-556
Optimization algorithms or heuristics in which the user interacts significantly either during the solution process or as part of post-optimality analysis are becoming increasingly popular. An important underlying premise of such man/machine systems is that there are some steps in solving a problem in which the computer has an advantage and other steps in which a human has an advantage. This paper first discusses how man/machine systems can be useful in facilitating model specification and revision, coping with aspects of a problem that are difficult to quantify and assisting in the solution process. We then survey successful systems that have been developed in the areas of vehicle scheduling, location problems, job shop scheduling, course scheduling, and planning language-based optimization. 相似文献
62.
Jacob Flachs 《Mathematical Programming》1981,20(1):327-347
General and quasi-concave non-differentiable cases of the maximization of the minimun between two functions are considered. With the aid of duality theory for mathematical programming involving conjugate-like operators and by defining a bifunction we construct a new Lagrangian and generate a class of perturbations. New saddle-point theorems are presented, and equivalence is proved between the existence of a saddle-point and the existence of a certain cone-supporting property of the perturbation function. These results suggest possible improvements in multiplier methods.This work was partially supported by a grant from Control Data. 相似文献
63.
R. R. Meyer 《Mathematical Programming》1983,26(1):21-39
Recursive separable programming algorithms based on local, two-segment approximations are described for the solution of separable
convex programs. Details are also given for the computation of lower bounds on the optimal value by both a primal and a dual
approach, and these approaches are compared. Computational comparisons of the methods are provided for a variety of test problems,
including a water supply application (with more than 600 constraints and more than 900 variables) and an econometric modelling
problem (with more than 200 variables).
Research supported by National Science Foundation Grants MCS74-20584 A02 and MCS-7901066. 相似文献
64.
Richard D. McBride 《Mathematical Programming》1980,18(1):49-61
A dynamic factorization algorithm is developed which algebraically partitions the basis inverse in such a manner so that the simplex method can be executed from a series of small inverses and the basis itself. This partition is maintained dynamically so that the additional memory required to represent the basis inverse reduces to this series of small inverses for in-core implementations.The algorithm is intended for use in solving general large-scale linear programming problems. This new method of basis representation should permit rather large problems to be solved completely in-core.Preliminary computational experience is presented and comparisons are made with Reid's sparsity-exploiting variant of the Bartels—Golub decomposition for linear programming bases. The computational experience indicated that a significant reduction in memory requirements can usually be obtained using the dynamic factorization approach with only a slight (up to about 20%) degradation of execution time.This research was supported in part by the Air Force Office of Scientific Research, Air Force System Command, USAF, under AFOSR Contract/Grant Number AFOSR-74-2715. 相似文献
65.
66.
A multiplier method with automatic limitation of penalty growth 总被引:3,自引:0,他引:3
This paper presents a multiplier method for solving optimization problems with equality and inequality constraints. The method realizes all the good features that were foreseen by R. Fletcher for this type of algorithm in the past, but which suffers from none of the drawbacks of the earlier attempts.Research sponsored by the National Science Foundation (RANN) Grant ENV76-04264 the National Science Foundation Grant ENG73-08214-A01 and the Sweden-American Foundation. 相似文献
67.
Fern Sassower Sisser 《Mathematical Programming》1981,20(1):110-121
The problem of minimizing a nonlinear objective function ofn variables, with continuous first and second partial derivatives, subject to nonnegativity constraints or upper and lower bounds on the variables is studied. The advisability of solving such a constrained optimization problem by making a suitable transformation of its variables in order to change the problem into one of unconstrained minimization is considered. A set of conditions which guarantees that every local minimum of the new unconstrained problem also satisfies the first-order necessary (Kuhn—Tucker) conditions for a local minimum of the original constrained problem is developed. It is shown that there are certain conditions under which the transformed objective function will maintain the convexity of the original objective function in a neighborhood of the solution. A modification of the method of transformations which moves away from extraneous stationary points is introduced and conditions under which the method generates a sequence of points which converges to the solution at a superlinear rate are given. 相似文献
68.
Ahmed Laghribi 《Rendiconti del Circolo Matematico di Palermo》2004,53(3):325-336
In this note we completely study the standard splitting of quasi-Pfister forms and their neighbors, and we include some general
results on standard splitting towers of totally singular quadratic forms.
The author was supported by the European research network HPRN-CT-2002-00287 “AlgebraicK-Theory, Linear Algebraic Groups and Related Structures”. 相似文献
69.
We study generalized equations of the following form: (render) where f is Fréchet differentiable in a neighborhood of a solution x* of (*) and g is Fréchet differentiable at x* and where F is a set-valued map acting in Banach spaces. We prove the existence of a sequence (xk) satisfying which is super-linearly convergent to a solution of (*). We also present other versions of this iterative procedure that have superlinear and quadratic convergence, respectively. 相似文献
0f(x)+g(x)+F(x),
70.
Mojia Huang 《Journal of the mechanics and physics of solids》2004,52(8):1827-1853
Herein we obtain a formula for the effective elastic stiffness tensor Ceff of an orthorhombic aggregate of cubic crystallites by the perturbation method. The effective elastic stiffness tensor of the polycrystal gives the relationship between volume average stress and volume average strain. Under Voigt's model, Reuss’ model and Man's theory, the elastic constitutive relation accounts for the effect of the orientation distribution function (ODF) up to terms linear in the texture coefficients. However, the formula derived in this paper delineates the effect of crystallographic texture on elastic response and shows quadratic texture dependence. The formula is very simple. We also consider the influence of grain shape to elastic constitutive relations of polycrystals. Some examples are given to compare computational results of the formula with those given by Voigt's model, Reuss's model, the finite element method, and the self-consistent method. In Section 3, we also present an expression of the perturbation displacement field, in which Green's function for an orthorhombic aggregate of cubic crystallites is included. 相似文献