全文获取类型
收费全文 | 1277篇 |
免费 | 35篇 |
国内免费 | 87篇 |
专业分类
化学 | 5篇 |
晶体学 | 1篇 |
力学 | 20篇 |
综合类 | 16篇 |
数学 | 1152篇 |
物理学 | 205篇 |
出版年
2024年 | 3篇 |
2023年 | 11篇 |
2022年 | 17篇 |
2021年 | 9篇 |
2020年 | 15篇 |
2019年 | 19篇 |
2018年 | 25篇 |
2017年 | 27篇 |
2016年 | 21篇 |
2015年 | 11篇 |
2014年 | 27篇 |
2013年 | 101篇 |
2012年 | 66篇 |
2011年 | 53篇 |
2010年 | 37篇 |
2009年 | 70篇 |
2008年 | 81篇 |
2007年 | 78篇 |
2006年 | 72篇 |
2005年 | 55篇 |
2004年 | 52篇 |
2003年 | 43篇 |
2002年 | 50篇 |
2001年 | 48篇 |
2000年 | 50篇 |
1999年 | 43篇 |
1998年 | 33篇 |
1997年 | 30篇 |
1996年 | 26篇 |
1995年 | 16篇 |
1994年 | 21篇 |
1993年 | 18篇 |
1992年 | 20篇 |
1991年 | 15篇 |
1990年 | 13篇 |
1989年 | 10篇 |
1988年 | 13篇 |
1987年 | 15篇 |
1986年 | 10篇 |
1985年 | 9篇 |
1984年 | 7篇 |
1983年 | 3篇 |
1982年 | 11篇 |
1981年 | 8篇 |
1980年 | 10篇 |
1979年 | 3篇 |
1978年 | 12篇 |
1977年 | 3篇 |
1976年 | 5篇 |
1974年 | 3篇 |
排序方式: 共有1399条查询结果,搜索用时 171 毫秒
71.
We consider an approach for ex post evaluation of approximate solutions obtained by a well known simple greedy method for
set packing. A performance bound is derived that is a function of the highest average reward per item over subsets as well
as the number of allocated subsets and ground items. This a posterior bound can enable much revelation of optimality when
the solution is near optimal. One of the advantages of the ex post analysis is that it does not require computing the optimal
solution to the LP relaxation. The ex post bound will not be guaranteed to reveal substantial levels of optimality for all
problem instances but can be a useful tool that is complementary to other traditional methods for ex post evaluation for the
set packing problem. 相似文献
72.
J. Hoffman 《国际流体数值方法杂志》2009,59(11):1241-1258
General Galerkin (G2) is a new computational method for turbulent flow, where a stabilized Galerkin finite element method is used to compute approximate weak solutions to the Navier–Stokes equations directly, without any filtering of the equations as in a standard approach to turbulence simulation, such as large eddy simulation, and thus no Reynolds stresses are introduced, which need modelling. In this paper, G2 is used to compute the drag coefficient cD for the flow past a circular cylinder at Reynolds number Re=3900, for which the flow is turbulent. It is found that it is possible to approximate cD to an accuracy of a few percent, corresponding to the accuracy in experimental results for this problem, using less than 105 mesh points, which makes the simulations possible using a standard PC. The mesh is adaptively refined until a stopping criterion is reached with respect to the error in a chosen output of interest, which in this paper is cD. Both the stopping criterion and the mesh‐refinement strategy are based on a posteriori error estimates, in the form of a space–time integral of residuals times derivatives of the solution of a dual problem, linearized at the approximate solution, and with data coupling to the output of interest. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
73.
Log-Sigmoid Multipliers Method in Constrained Optimization 总被引:10,自引:0,他引:10
Roman A. Polyak 《Annals of Operations Research》2001,101(1-4):427-460
In this paper we introduced and analyzed the Log-Sigmoid (LS) multipliers method for constrained optimization. The LS method is to the recently developed smoothing technique as augmented Lagrangian to the penalty method or modified barrier to classical barrier methods. At the same time the LS method has some specific properties, which make it substantially different from other nonquadratic augmented Lagrangian techniques.We established convergence of the LS type penalty method under very mild assumptions on the input data and estimated the rate of convergence of the LS multipliers method under the standard second order optimality condition for both exact and nonexact minimization.Some important properties of the dual function and the dual problem, which are based on the LS Lagrangian, were discovered and the primal–dual LS method was introduced. 相似文献
74.
75.
A. V. Zykina 《Computational Mathematics and Mathematical Physics》2008,48(11):1971-1980
The concept of inverse complementarity for a parametric family of optimization problems is introduced. This concept is an
effective tool for solving complicated applied problems arising in socioeconomic systems. As an example, a nonlinear resource
deficit model is constructed in which the equilibrium is characterized by an external market value of resources coinciding
with internal objectively determined resource estimates. An extraproximal method is proposed for computing an equilibrium
solution. The convergence of the method is proved.
Original Russian Text. A.V. Zykina, 2008, published in Zhurnal Vychislitel’noi Matematiki i Matematicheskoi Fiziki, 2008,
Vol. 48, No. 11, pp. 1968–1978. 相似文献
76.
Marc Chardin Kamran Divaani-Aazar 《Proceedings of the American Mathematical Society》2008,136(8):2749-2754
We prove a duality theorem for graded algebras over a field that implies several known duality results: graded local duality, versions of Serre duality for local cohomology and of Suzuki duality for generalized local cohomology, and Herzog-Rahimi bigraded duality.
77.
We show that the Priestley sum of finite trees contains no cyclic finite poset.
The first author would like to express his thanks for support from project LN 1M0021620808 of the Ministry of Education of
the Czech Republic. The second author would like to express his thanks for support from project 1M0021620808 of the Ministry
of Education of the Czech Republic, from the NSERC of Canada and from a PROF grant from the University of Denver. The third
author would like to express his thanks for the support from the NSERC of Canada and for partial support from the project
1M0021620808 of the Ministry of Education of the Czech Republic. 相似文献
78.
79.
This paper studies the relationship between product quality as defined by tolerances on the product to tolerances on the parts. All the standard sure-fit and the statistical-fit tolerancing models, which seek to find the least cost tolerances for the parts given the product specification, are found to be convex. Thus conjugate duality provides a unifying framework for studying the relationship between quality and tolerancing and the analysis and solution of such problems. Moreover this convexity is maintained even with the addition of quality loss functions. Quality loss is modeled on the basis of parts or the product. The analysis leads to an analytic solution to a number of models including the quality loss model. 相似文献
80.
A reflexive topological group G is called strongly reflexive if each closed subgroup and each Hausdorff quotient of the group G and of its dual group is reflexive. In this paper we establish an adequate concept of strong reflexivity for convergence groups. We prove that complete metrizable nuclear groups and products of countably many locally compact topological groups are BB-strongly reflexive. 相似文献