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**排序方式：**共有3666条查询结果，搜索用时 31 毫秒

1.

A nonsmooth version of Newton's method

**总被引：68，自引：0，他引：68**Newton's method for solving a nonlinear equation of several variables is extended to a nonsmooth case by using the generalized Jacobian instead of the derivative. This extension includes the B-derivative version of Newton's method as a special case. Convergence theorems are proved under the condition of semismoothness. It is shown that the gradient function of the augmented Lagrangian for

*C*^{2}-nonlinear programming is semismooth. Thus, the extended Newton's method can be used in the augmented Lagrangian method for solving nonlinear programs.This author's work is supported in part by the Australian Research Council.This author's work is supported in part by the National Science Foundation under grant DDM-8721709. 相似文献2.

On the limited memory BFGS method for large scale optimization

**总被引：48，自引：0，他引：48**We study the numerical performance of a limited memory quasi-Newton method for large scale optimization, which we call the L-BFGS method. We compare its performance with that of the method developed by Buckley and LeNir (1985), which combines cycles of BFGS steps and conjugate direction steps. Our numerical tests indicate that the L-BFGS method is faster than the method of Buckley and LeNir, and is better able to use additional storage to accelerate convergence. We show that the L-BFGS method can be greatly accelerated by means of a simple scaling. We then compare the L-BFGS method with the partitioned quasi-Newton method of Griewank and Toint (1982a). The results show that, for some problems, the partitioned quasi-Newton method is clearly superior to the L-BFGS method. However we find that for other problems the L-BFGS method is very competitive due to its low iteration cost. We also study the convergence properties of the L-BFGS method, and prove global convergence on uniformly convex problems.This work was supported by the Applied Mathematical Sciences subprogram of the Office of Energy Research, U.S. Department of Energy, under contract DE-FG02-87ER25047, and by National Science Foundation Grant No. DCR-86-02071. 相似文献

3.

Two families of mixed finite elements for second order elliptic problems

**总被引：32，自引：2，他引：30**Summary Two families of mixed finite elements, one based on triangles and the other on rectangles, are introduced as alternatives to the usual Raviart-Thomas-Nedelec spaces. Error estimates in

*L*^{2}*()*and*H*^{–5}*()*are derived for these elements. A hybrid version of the mixed method is also considered, and some superconvergence phenomena are discussed. 相似文献4.

Re-entrant lines

**总被引：27，自引：0，他引：27** P. R. Kumar 《Queueing Systems》1993,13(1-3):87-110

Traditionally, manufacturing systems have mainly been treated as either job shops or flow shops. In job shops, parts may arrive with random routes, with each route having a low volume. In flow shops, the routes are fixed and acyclic, as in assembly lines. With the advent of semiconductor manufacturing plants, and more recently, thin film lines, this dichotomy needs to be expanded to consider another class of systems, which we call re-entrant lines. The distinguishing feature of these manufacturing systems is that parts visit some machines more than once at different stages of processing.Scheduling problems arise because several parts at different stages of processing may be in contention with each other for service at the same machine. There may be uncertainties in the form of random service or set-up times, as well as random machine failures and repairs. The goal of scheduling is to improve performance measures such as mean sojourn time in the system, which is also known as the mean cycle-time, or the variance of the cycle-time.In this paper we provide a tutorial account of some recent results in this field. We describe several scheduling policies of interest, and provide some results concerning their stability and performance. Several open problems are suggested.The research reported here has been partially supported by the National Science Foundation under Grant No. ECS-90-25007, and the Joint Services Electronics Program under Contract No. N00014-84-C-0149. 相似文献

5.

Projected gradient methods for linearly constrained problems

**总被引：23，自引：0，他引：23** 《Mathematical Programming》1987,39(1):93-116

The aim of this paper is to study the convergence properties of the gradient projection method and to apply these results
to algorithms for linearly constrained problems. The main convergence result is obtained by defining a projected gradient,
and proving that the gradient projection method forces the sequence of projected gradients to zero. A consequence of this
result is that if the gradient projection method converges to a nondegenerate point of a linearly constrained problem, then
the active and binding constraints are identified in a finite number of iterations. As an application of our theory, we develop
quadratic programming algorithms that iteratively explore a subspace defined by the active constraints. These algorithms are
able to drop and add many constraints from the active set, and can either compute an accurate minimizer by a direct method,
or an approximate minimizer by an iterative method of the conjugate gradient type. Thus, these algorithms are attractive for
large scale problems. We show that it is possible to develop a finite terminating quadratic programming algorithm without
non-degeneracy assumptions.
Work supported in part by the Applied Mathematical Sciences subprogram of the Office of Energy Research of the U.S. Department
of Energy under Contract W-31-109-Eng-38.
Work supported in part by the Applied Mathematical Sciences subprogram of the Office of Energy Research of the U.S. Department
of Energy under Contract W-31-109-Eng-38. 相似文献

6.

An Inventory-Location Model: Formulation, Solution Algorithm and Computational Results

**总被引：18，自引：0，他引：18** Mark S. Daskin Collette R. Coullard Zuo-Jun Max Shen 《Annals of Operations Research》2002,110(1-4):83-106

We introduce a distribution center (DC) location model that incorporates working inventory and safety stock inventory costs at the distribution centers. In addition, the model incorporates transport costs from the suppliers to the DCs that explicitly reflect economies of scale through the use of a fixed cost term. The model is formulated as a non-linear integer-programming problem. Model properties are outlined. A Lagrangian relaxation solution algorithm is proposed. By exploiting the structure of the problem we can find a low-order polynomial algorithm for the non-linear integer programming problem that must be solved in solving the Lagrangian relaxation subproblems. A number of heuristics are outlined for finding good feasible solutions. In addition, we describe two variable forcing rules that prove to be very effective at forcing candidate sites into and out of the solution. The algorithms are tested on problems with 88 and 150 retailers. Computation times are consistently below one minute and compare favorably with those of an earlier proposed set partitioning approach for this model (Shen, 2000; Shen, Coullard and Daskin, 2000). Finally, we discuss the sensitivity of the results to changes in key parameters including the fixed cost of placing orders. Significant reductions in these costs might be expected from e-commerce technologies. The model suggests that as these costs decrease it is optimal to locate additional facilities. 相似文献

7.

A trust region method based on interior point techniques for nonlinear programming

**总被引：14，自引：0，他引：14**An algorithm for minimizing a nonlinear function subject to nonlinear inequality constraints is described. It applies sequential
quadratic programming techniques to a sequence of barrier problems, and uses trust regions to ensure the robustness of the
iteration and to allow the direct use of second order derivatives. This framework permits primal and primal-dual steps, but
the paper focuses on the primal version of the new algorithm. An analysis of the convergence properties of this method is
presented.
Received: May 1996 / Accepted: August 18, 2000?Published online October 18, 2000 相似文献

8.

Optimal solutions of Linear Programming problems may become severely infeasible if the nominal data is slightly perturbed.
We demonstrate this phenomenon by studying 90 LPs from the well-known NETLIB collection. We then apply the Robust Optimization
methodology (Ben-Tal and Nemirovski [1–3]; El Ghaoui et al. [5, 6]) to produce “robust” solutions of the above LPs which are
in a sense immuned against uncertainty. Surprisingly, for the NETLIB problems these robust solutions nearly lose nothing in
optimality.
Received: July 1999 / Accepted: May 2000?Published online July 20, 2000 相似文献

9.

Bifurcations of heteroclinic loops

**总被引：14，自引：0，他引：14**By generalizing the Floquet method from periodic systems to systems with exponential dichotomy, a local coordinate system
is established in a neighborhood of the heteroclinic loop Γ to study the bifurcation problems of homoclinic and periodic orbits.
Asymptotic expressions of the bifurcation surfaces and their relative positions are given. The results obtained in literature
concerned with the 1-hom bifurcation surfaces are improved and extended to the nontransversal case. Existence regions of the
1-per orbits bifurcated from Γ are described, and the uniqueness and incoexistence of the 1-hom and 1-per orbit and the inexistence
of the 2-hom and 2-per orbit are also obtained.
Project supported by the National Natural Science Foundation of China (Grant No. 19771037) and the National Science Foundation
of America # 9357622. This paper was completed when the first author was visiting Northwestern University. 相似文献

10.

Summary Two families of mixed finite elements, one based on simplices and the other on cubes, are introduced as alternatives to the usual Raviart-Thomas-Nedelec spaces. These spaces are analogues of those introduced by Brezzi, Douglas, and Marini in two space variables. Error estimates in

*L*^{2}and*H*^{–s}are derived. 相似文献