全文获取类型
收费全文 | 8144篇 |
免费 | 323篇 |
国内免费 | 406篇 |
专业分类
化学 | 78篇 |
力学 | 454篇 |
综合类 | 44篇 |
数学 | 5546篇 |
物理学 | 344篇 |
综合类 | 2407篇 |
出版年
2024年 | 10篇 |
2023年 | 63篇 |
2022年 | 60篇 |
2021年 | 67篇 |
2020年 | 113篇 |
2019年 | 128篇 |
2018年 | 126篇 |
2017年 | 152篇 |
2016年 | 150篇 |
2015年 | 177篇 |
2014年 | 297篇 |
2013年 | 635篇 |
2012年 | 362篇 |
2011年 | 415篇 |
2010年 | 347篇 |
2009年 | 532篇 |
2008年 | 523篇 |
2007年 | 575篇 |
2006年 | 465篇 |
2005年 | 415篇 |
2004年 | 317篇 |
2003年 | 326篇 |
2002年 | 278篇 |
2001年 | 245篇 |
2000年 | 225篇 |
1999年 | 202篇 |
1998年 | 228篇 |
1997年 | 178篇 |
1996年 | 154篇 |
1995年 | 105篇 |
1994年 | 117篇 |
1993年 | 95篇 |
1992年 | 97篇 |
1991年 | 59篇 |
1990年 | 59篇 |
1989年 | 48篇 |
1988年 | 64篇 |
1987年 | 51篇 |
1986年 | 52篇 |
1985年 | 45篇 |
1984年 | 41篇 |
1983年 | 24篇 |
1982年 | 34篇 |
1981年 | 30篇 |
1980年 | 44篇 |
1979年 | 39篇 |
1978年 | 28篇 |
1977年 | 26篇 |
1976年 | 33篇 |
1974年 | 7篇 |
排序方式: 共有8873条查询结果,搜索用时 31 毫秒
61.
Veli B. Shakhmurov 《Journal of Mathematical Analysis and Applications》2007,327(2):1182-1201
The nonlocal boundary value problems for anisotropic partial differential-operator equations with a dependent coefficients are studied. The principal parts of the appropriate generated differential operators are nonself-adjoint. Several conditions for the maximal regularity and the fredholmness in Banach-valued Lp-spaces of these problems are given. These results permit us to establish that the inverse of corresponding differential operators belongs to Schatten q-class. Some spectral properties of the operators are investigated. In applications, the nonlocal BVP's for quasielliptic partial differential equations and for systems of quasielliptic equations on cylindrical domain are studied. 相似文献
62.
Gerhard Starke 《Numerische Mathematik》1997,78(1):103-117
Summary. The convergence rate of Krylov subspace methods for the solution of nonsymmetric systems of linear equations, such as GMRES
or FOM, is studied. Bounds on the convergence rate are presented which are based on the smallest real part of the field of
values of the coefficient matrix and of its inverse. Estimates for these quantities are available during the iteration from
the underlying Arnoldi process. It is shown how these bounds can be used to study the convergence properties, in particular,
the dependence on the mesh-size and on the size of the skew-symmetric part, for preconditioners for finite element discretizations
of nonsymmetric elliptic boundary value problems. This is illustrated for the hierarchical basis and multilevel preconditioners
which constitute popular preconditioning strategies for such problems.
Received May 3, 1996 相似文献
63.
This study provides a stability theory for the nonlinear least-squares formulation of estimating the diffusion coefficient in a two-point boundary-value problem from an error-corrupted observation of the state variable. It is based on analysing the projection of the observation on the nonconvex attainable set.This research was started while G. Chavent visited the Technical University of Graz. Support through the Steiermaerkische Landesregierung is gratefully acknowledged. 相似文献
64.
Marco Marletta 《Advances in Computational Mathematics》1994,2(2):155-184
This paper discusses the numerical solution of eigenvalue problems for Hamiltonian systems of ordinary differential equations.
Two new codes are presented which incorporate the algorithms described here; to the best of the author’s knowledge, these
are the first codes capable of solving numerically such general eigenvalue problems. One of these implements a new new method
of solving a differential equation whose solution is a unitary matrix. Both codes are fully documented and are written inPfort-verifiedFortran 77, and will be available in netlib/aicm/sl11f and netlib/aicm/sl12f. 相似文献
65.
A. Gorban' 《Mathematical and Computer Modelling》2002,35(13):7047-1370
An explicitly solvable Riabouchinsky model with a partially penetrable obstacle is introduced. This model applied to the estimation of the efficiency of free flow turbines allows us to take into account the pressure drop past the lamina. 相似文献
66.
Francisco‐Javier Sayas 《Numerical Methods for Partial Differential Equations》2003,19(5):555-570
This article presents and analyzes a simple method for the exterior Laplace equation through the coupling of finite and boundary element methods. The main novelty is the use of a smooth parametric artificial boundary where boundary elements fit without effort together with a straight approximate triangulation in the bounded area, with the coupling done only in nodes. A numerically integrated version of the algorithm is also analyzed. Finally, an isoparametric variant with higher order is proposed. © 2003 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 19: 555–570, 2003 相似文献
67.
We consider the least squares approximation of gridded 2D data by tensor product splines with free knots. The smoothing functional to be minimized—a generalization of the univariate Schoenberg functional—is chosen in such a way that the solution of the bivariate problem separates into the solution of a sequence of univariate problems in case of fixed knots. The resulting optimization problem is a constrained separable least squares problem with tensor product structure. Based on some ideas developed by the authors for the univariate case, an efficient method for solving the specially structured 2D problem is proposed, analyzed and tested on hand of some examples from the literature. 相似文献
68.
Rafael Caballero Mercedes González Flor M Guerrero Julián Molina Concepción Paralera 《European Journal of Operational Research》2007
In this work we present a multiobjective location routing problem and solve it with a multiobjective metaheuristic procedure. In this type of problem, we have to locate some plants within a set of possible locations to meet the demands of a number of clients with multiple objectives. This type of model is used to solve a problem with real data in the region of Andalusia (Spain). Thus, we study the location of two incineration plants for the disposal of solid animal waste from some preestablished locations in Andalusia, and design the routes to serve the different slaughterhouses in this region. This must be done while taking into account certain economic objectives (start-up, maintenance, and transport costs) and social objectives (social rejection by towns on the truck routes, maximum risk as an equity criterion, and the negative implications for towns close to the plant). 相似文献
69.
常振江 《辽宁师范大学学报(自然科学版)》2003,26(1):109-112
利用统计分析方法,对辽宁师范大理科学生成绩分布情况进行了分析;给出了一种评估试卷命题质量的简便易行的方法一用正态曲线拟合的方法,实际证明,效果很好。 相似文献
70.
L.E. Payne 《Journal of Mathematical Analysis and Applications》2003,284(1):283-293
We consider some initial-boundary value problems for the linear and nonlinear heat equation where the gradient of the solution is prescribed on the boundary. Assuming that a solution exists, we obtain bounds for the solution and its gradient by maximum principle arguments or by means of differential and integral inequalities. 相似文献