全文获取类型
收费全文 | 15064篇 |
免费 | 1122篇 |
国内免费 | 772篇 |
专业分类
化学 | 1516篇 |
晶体学 | 22篇 |
力学 | 877篇 |
综合类 | 218篇 |
数学 | 12307篇 |
物理学 | 2018篇 |
出版年
2023年 | 82篇 |
2022年 | 131篇 |
2021年 | 214篇 |
2020年 | 225篇 |
2019年 | 261篇 |
2018年 | 264篇 |
2017年 | 361篇 |
2016年 | 388篇 |
2015年 | 284篇 |
2014年 | 646篇 |
2013年 | 955篇 |
2012年 | 810篇 |
2011年 | 692篇 |
2010年 | 674篇 |
2009年 | 883篇 |
2008年 | 958篇 |
2007年 | 1012篇 |
2006年 | 797篇 |
2005年 | 733篇 |
2004年 | 599篇 |
2003年 | 544篇 |
2002年 | 577篇 |
2001年 | 517篇 |
2000年 | 492篇 |
1999年 | 455篇 |
1998年 | 369篇 |
1997年 | 333篇 |
1996年 | 317篇 |
1995年 | 298篇 |
1994年 | 220篇 |
1993年 | 206篇 |
1992年 | 203篇 |
1991年 | 180篇 |
1990年 | 139篇 |
1989年 | 106篇 |
1988年 | 113篇 |
1987年 | 91篇 |
1986年 | 106篇 |
1985年 | 136篇 |
1984年 | 109篇 |
1983年 | 34篇 |
1982年 | 69篇 |
1981年 | 54篇 |
1980年 | 50篇 |
1979年 | 47篇 |
1978年 | 58篇 |
1977年 | 60篇 |
1976年 | 34篇 |
1975年 | 15篇 |
1974年 | 16篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
In this paper we propose a general integration scheme for a Multi-Criteria Decision Making model of the Multi-Attribute Utility
Theory in Constraint Programming. We introduce the Choquet integral as a general aggregation function for multi-criteria optimization
problems and define the Choquet global constraint that propagates this function during the Branch-and-Bound search. Finally the benefits of the propagation
of the Choquet constraint are evaluated on the examination timetabling problem. 相似文献
92.
Dmitry I. Belov Ronald D. Armstrong 《Computational Optimization and Applications》2006,33(2-3):319-332
This paper introduces a novel approach for extracting the maximum number of non-overlapping test forms from a large collection
of overlapping test sections assembled from a given item bank. The approach involves solving maximum set packing problems
(MSPs). A branch-and-bound MSP algorithm is developed along with techniques adapted from constraint programming to estimate
lower and upper bounds on the optimal MSP solution. The algorithm is general and can be applied in other applications including
combinatorial auctions. The results of computer simulations and experiments with an operational item bank are presented.
An erratum to this article is available at . 相似文献
93.
Regina S. Burachik Rafail N. Gasimov Nergiz A. Ismayilova C. Yalçin. Kaya 《Journal of Global Optimization》2006,34(1):55-78
We study convergence properties of a modified subgradient algorithm, applied to the dual problem defined by the sharp augmented
Lagrangian. The primal problem we consider is nonconvex and nondifferentiable, with equality constraints. We obtain primal
and dual convergence results, as well as a condition for existence of a dual solution. Using a practical selection of the
step-size parameters, we demonstrate the algorithm and its advantages on test problems, including an integer programming and
an optimal control problem.
*Partially Supported by 2003 UniSA ITEE Small Research Grant Ero2.
Supported by CAPES, Brazil, Grant No. 0664-02/2, during her visit to the School of Mathematics and Statistics, UniSA. 相似文献
94.
Ying Zhang Gang Hu Shigang Chen H.A. Cerdeira 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,27(3):381-384
A method of controlling global stochasticity in Hamiltonian systems by applying nonlinear perturbation is proposed. With the
well-known standard map we demonstrate that this control method can convert global stochasticity into regular motion in a
wide chaotic region for arbitrary initial condition, in which the control signal remains very weak after a few kicks. The
system in which chaos has been controlled approximates to the original Hamiltonian system, and this approach appears robust
against small external noise. The mechanism underlying this high control efficiency is intuitively explained.
Received 15 January 2002 Published online 6 June 2002 相似文献
95.
Michael Giudici 《Designs, Codes and Cryptography》2006,39(2):163-172
We determine all linear codes C containing the constant code E, for which there is a weight-preserving group of semilinear automorphisms which acts transitively on the set of nontrivial
cosets of E in C.
Michael Giudici - The author holds an Australian Postdoctoral Fellowship. 相似文献
96.
Linear complexity and linear complexity profile are important characteristics of a sequence for applications in cryptography
and Monte-Carlo methods.
The nonlinear congruential method is an attractive alternative to the classical linear congruential method for pseudorandom
number generation.
Recently, a weak lower bound on the linear complexity profile of a general nonlinear congruential pseudorandom number generator
was proven by Gutierrez, Shparlinski and the first author. For most nonlinear generators a much stronger lower bound is expected.
Here, we obtain a much stronger lower bound on the linear complexity profile of nonlinear congruential pseudorandom number
generators with Dickson polynomials. 相似文献
97.
全生寅 《数学的实践与认识》2006,36(1):253-256
证明了线性规划的K uhn-Tucker条件蕴含着它的对偶问题,解释了L agrange乘子的意义.进而显示了K-T条件中的互补松驰性与对偶线性规划的互补松紧定理之间的联系. 相似文献
98.
利用已知弹性函数级联上高非线性度多输出布尔函数的方法构造(n,m,t)弹性函数,其非线性度为2^n-1-2^n-l/2-1+2^l/2.nlmax(n-l,m,t),在相同条件下改进了Kurosawa的非线性度2^n-1-2^n-l/2-1.特别地,本文构造了两类具体的向量弹性函数,得到两个不同的非线性度.本文所得函数的非线性度在大多数情况下是比较好的. 相似文献
99.
100.
Hadi Mohammadi Bidhandi 《Annals of Operations Research》2006,143(1):237-250
This paper develops a mathematical model for project time compression problems in CPM/PERT type networks. It is noted this
formulation of the problem will be an adequate approximation for solving the time compression problem with any continuous
and non-increasing time-cost curve. The kind of this model is Mixed Integer Linear Program (MILP) with zero-one variables,
and the Benders' decomposition procedure for analyzing this model has been developed. Then this paper proposes a new approach
based on the surrogating method for solving these problems. In addition, the required computer programs have been prepared
by the author to execute the algorithm. An illustrative example solved by the new algorithm, and two methods are compared
by several numerical examples. Computational experience with these data shows the superiority of the new approach. 相似文献