全文获取类型
收费全文 | 532篇 |
免费 | 6篇 |
国内免费 | 8篇 |
专业分类
化学 | 89篇 |
晶体学 | 1篇 |
力学 | 71篇 |
综合类 | 2篇 |
数学 | 288篇 |
物理学 | 95篇 |
出版年
2024年 | 1篇 |
2023年 | 4篇 |
2022年 | 6篇 |
2021年 | 5篇 |
2019年 | 1篇 |
2018年 | 5篇 |
2017年 | 2篇 |
2016年 | 2篇 |
2015年 | 4篇 |
2014年 | 8篇 |
2013年 | 195篇 |
2012年 | 41篇 |
2011年 | 13篇 |
2010年 | 10篇 |
2009年 | 13篇 |
2008年 | 12篇 |
2007年 | 14篇 |
2006年 | 15篇 |
2005年 | 9篇 |
2004年 | 7篇 |
2003年 | 9篇 |
2002年 | 11篇 |
2001年 | 11篇 |
2000年 | 7篇 |
1999年 | 12篇 |
1998年 | 10篇 |
1997年 | 10篇 |
1996年 | 6篇 |
1995年 | 11篇 |
1994年 | 6篇 |
1993年 | 5篇 |
1992年 | 6篇 |
1991年 | 3篇 |
1990年 | 2篇 |
1989年 | 2篇 |
1988年 | 6篇 |
1987年 | 12篇 |
1986年 | 7篇 |
1985年 | 13篇 |
1984年 | 8篇 |
1983年 | 7篇 |
1982年 | 3篇 |
1981年 | 3篇 |
1980年 | 3篇 |
1979年 | 5篇 |
1978年 | 1篇 |
排序方式: 共有546条查询结果,搜索用时 15 毫秒
481.
《Optimization》2012,61(2):255-269
Constrained Markov decision processes with compact state and action spaces are studied under long-run average reward or cost criteria. By introducing a corresponding Lagrange function, a saddle-point theorem is given, by which the existence of a constrained optimal pair of initial state distribution and policy is shown. Also, under the hypothesis of Doeblin, the functional characterization of a constrained optimal policy is obtained 相似文献
482.
In this paper we study time inhomogeneous versions of one-dimensional Stochastic Differential Equations (SDE) involving the Local Time of the unknown process on curves. After proving existence and uniqueness for these SDEs under mild assumptions, we explore their link with Parabolic Differential Equations (PDE) with transmission conditions. We study the regularity of solutions of such PDEs and ensure the validity of a Feynman–Kac representation formula. These results are then used to characterize the solutions of these SDEs as time inhomogeneous Markov Feller processes. 相似文献
483.
A new algorithm is proposed which, under mild assumptions, generates a sequence{x
i
} that starting at any point inR
n
will converge to a setX defined by a mixed system of equations and inequalities. Any iteration of the algorithm requires the solution of a linear programming problem with relatively few constraints. By only assuming that the functions involved are continuously differentiable a superlinear rate of convergence is achieved. No convexity whatsoever is required by the algorithm. 相似文献
484.
本文对多元多项式齐次方程组给出一种解法,并给出其解子模的基所含向量的个数在最坏情况时的下界。 相似文献
485.
This note presents a new piecewise linear homotopy continuation method for solving a system of nonlinear equations. The important
feature of the method is the use of an odd map for the artificial level of the homotopy. Some sufficient conditions for the
global convergence of the method are given. They are different from the known conditions for the global convergence of the
existing homotopy continuation methods. Specifically, they cover all the systems of nondegenerate linear equations.
Partially supported by the Sakkokai Foundation and by the Grand-in-Aid for Scientific Research of the Ministry of Education
and Culture No. 58750265.
Partially supported by the Grant-in-Aid for Scientific Research of the Ministry of Education and Culture No. 56460103. 相似文献
486.
SolveMaximumResolutionofaFuzzyRelatinEquationinFiniteStepsTXSolveMaximumResolutionofaFuzzyRelationEquationinFiniteStepsYangZhe... 相似文献
487.
约束线性方程组通解的显式表示及Cramer法则 总被引:7,自引:3,他引:4
陈永林 《高校应用数学学报(A辑)》1993,(1):61-70
本文研究了一般的约束线性方程组Ax=b,x∈T, (1.1)其中A∈C~(m×n),b∈R(A),T为C~n中任意取定的子空间。给出了(1.1)有唯一解的充要条件;在有唯一解时,利用B-D逆(A~*A)_((T))~((-1))给出了唯一解的显式及cramer法则;在有解但解不唯一时,利用B-D逆(A~*A)_((?))~((-1))(这里(?)=R(R_TA~*))给出了(1.1)的通解的显式及Cramer法则。其结果改进并推广了文[2,3,4,5,6]中的有关结果。 另外,本文研究了A的T-约束M-P逆(AP_T)~+与A~*A的B-D逆(A~*A)_((?))~((-1))的关系,证明了下列事实:(AP_T)~+=(A~*A)_((?))~((-1))A~*,特别,当T∩N(A)={0}时,(AP_T)~+=(A~*A)_((?))~((-1))A~*。 相似文献
488.
Numerical solutions are often inaccurate because conventional co-ordinate systems do not represent the complex physical boundaries accurately. In the present work, the numerical solution of linear shallow water wave equations has been obtained by transforming the physical domain into a rectangular computational domain using elliptic differential operators. This work is part of a programme to develop three-dimensional body-fit grid systems for environmental flows. Solutions have been obtained for a cylindrical container and also a parabolic container. The initial conditions chosen are the ones for which analytical solutions exist. The numerical solutions compare well with analytical solutions. 相似文献
489.
重点研究线性Fuzzy方程组=的解,其中矩阵和向量均以有限Fuzzy数为其元素。文中首先指出,使用扩展原理和Fuzzy数运算规则有时会导致=没有解。本文以实广义逆矩阵为工具,给出了=的六个解,证明了它们都是Rn上的Fuzzy向量。 相似文献
490.
Charles Koeck 《国际流体数值方法杂志》1985,5(5):483-500
The unsteady Euler equations are numerically solved using the finite volume one-step scheme recently developed by Ron-Ho Ni. The multiple-grid procedure of Ni is also implemented. The flows are assumed to be homo-enthalpic; the energy equation is eliminated and the static pressure is determined by the steady Bernoulli equation; a local time-step technique is used. Inflow and outflow boundaries are treated with the compatibility relations method of ONERA. The efficiency of the multiple-grid scheme is demonstrated by a two-dimensional calculation (transonic flow past the NACA 12 aerofoil) and also by a three-dimensional one (transonic lifting flow past the M6 wing). The third application presented shows the ability of the method to compute the vortical flow around a delta wing with leading-edge separation. No condition is applied at the leading-edge; the vortex sheets are captured in the same sense as shock waves. Results indicate that the Euler equations method is well suited for the prediction of flows with shock waves and contact discontinuities, the multiple-grid procedure allowing a substantial reduction of the computational time. 相似文献