全文获取类型
收费全文 | 378篇 |
免费 | 18篇 |
国内免费 | 19篇 |
专业分类
化学 | 8篇 |
力学 | 28篇 |
综合类 | 10篇 |
数学 | 363篇 |
物理学 | 6篇 |
出版年
2023年 | 1篇 |
2022年 | 2篇 |
2021年 | 2篇 |
2020年 | 5篇 |
2019年 | 4篇 |
2018年 | 6篇 |
2017年 | 9篇 |
2016年 | 7篇 |
2015年 | 9篇 |
2014年 | 7篇 |
2013年 | 16篇 |
2012年 | 18篇 |
2011年 | 12篇 |
2010年 | 8篇 |
2009年 | 15篇 |
2008年 | 20篇 |
2007年 | 20篇 |
2006年 | 27篇 |
2005年 | 22篇 |
2004年 | 14篇 |
2003年 | 16篇 |
2002年 | 18篇 |
2001年 | 10篇 |
2000年 | 11篇 |
1999年 | 12篇 |
1998年 | 8篇 |
1997年 | 10篇 |
1996年 | 14篇 |
1995年 | 10篇 |
1994年 | 7篇 |
1993年 | 4篇 |
1992年 | 7篇 |
1991年 | 7篇 |
1990年 | 6篇 |
1989年 | 7篇 |
1988年 | 5篇 |
1987年 | 7篇 |
1986年 | 1篇 |
1984年 | 3篇 |
1983年 | 1篇 |
1982年 | 5篇 |
1981年 | 4篇 |
1980年 | 1篇 |
1979年 | 4篇 |
1978年 | 2篇 |
1977年 | 4篇 |
1976年 | 6篇 |
1974年 | 1篇 |
排序方式: 共有415条查询结果,搜索用时 15 毫秒
1.
We consider a Bolza optimal control problem with state constraints. It is well known that under some technical assumptions every strong local minimizer of this problem satisfies first order necessary optimality conditions in the form of a constrained maximum principle. In general, the maximum principle may be abnormal or even degenerate and so does not provide a sufficient information about optimal controls. In the recent literature some sufficient conditions were proposed to guarantee that at least one maximum principle is nondegenerate, cf. [A.V. Arutyanov, S.M. Aseev, Investigation of the degeneracy phenomenon of the maximum principle for optimal control problems with state constraints, SIAM J. Control Optim. 35 (1997) 930–952; F. Rampazzo, R.B. Vinter, A theorem on existence of neighbouring trajectories satisfying a state constraint, with applications to optimal control, IMA 16 (4) (1999) 335–351; F. Rampazzo, R.B. Vinter, Degenerate optimal control problems with state constraints, SIAM J. Control Optim. 39 (4) (2000) 989–1007]. Our aim is to show that actually conditions of a similar nature guarantee normality of every nondegenerate maximum principle. In particular we allow the initial condition to be fixed and the state constraints to be nonsmooth. To prove normality we use J. Yorke type linearization of control systems and show the existence of a solution to a linearized control system satisfying new state constraints defined, in turn, by linearization of the original set of constraints along an extremal trajectory. 相似文献
2.
On the properties of solutions to the Goursat-Darboux problem with boundary and distributed controls
N. I. Pogodaev 《Siberian Mathematical Journal》2007,48(5):897-912
We consider a control system described by the Goursat-Darboux equation. The system is controlled by distributed and boundary controls. The controls are subject to the constraints given as multivalued mappings with closed, possibly nonconvex, values depending on the phase variable. Alongside the initial constraints, we consider the convexified constraints and the constraints whose values are the extreme points of the convexified constraints. We study the questions of existence of solutions and establish connections between the solutions under various constraints. 相似文献
3.
W. Kotarski 《Journal of Optimization Theory and Applications》1987,54(3):565-573
Combining the results of Walczak (Ref. 1) and Lasiecka (Refs. 2 and 3), we extend the well-known Dubovicki-Milutin theorem in two directions: (i) We allow for treatment of several equality constraints in optimization problems; and (ii) We assume less regularity of optimization problems by requiring the existence of external cones instead of tangent cones. An example of an optimization problem is also considered. 相似文献
4.
5.
J. Kogan 《Journal of Optimization Theory and Applications》1989,63(2):225-260
In this paper, we study intersections of extremals in a linear-quadratic Bolza problem of optimal control. The structure of the inter-sections is described. We show that this structure implies the semipositive definiteness of the quadratic cost functional. In addition, we derive necessary and sufficient conditions for the existence of minimizers. 相似文献
6.
讨论了一维奇异P-Laplace方程{φp(u′))′ f(t,u)=0,t∈(0,1);u(0=u(1)=0存在C^1[0,1]或C[0,1]正解的一个充分必要条件.用到的方法主要有上下解方法和Schaude,不动点定理. 相似文献
7.
讨论一类多滞量抛物型时滞偏微分方程解的振动性质,获得了其一切解振动的充要条件及一些充分条件;指出了其与普通抛物型偏微分方程解的质的差异. 相似文献
8.
年龄相关的种群扩散系统的最优分布控制 总被引:5,自引:1,他引:4
本文讨论年龄相关的种群扩散系统的最优分布控制 ,证明了最优分布控制的存在性 ,得到了分布控制为最优的充分必要条件及确定最优控制的最优性组 . 相似文献
9.
10.
In this paper, we treat a domain optimization problem in which the boundary-value problem is a Neumann problem. In the case where the domain is in a three-dimensional Euclidean space, the first-order and the second-order necessary conditions which the optimal domain must satisfy are derived under a constraint which is the generalization of the requisite of constant volume.Portions of this paper were presented at the 13th IFIP Conference on System Modelling and Optimization, Tokyo, Japan, 1987. 相似文献