全文获取类型
收费全文 | 3800篇 |
免费 | 243篇 |
国内免费 | 480篇 |
专业分类
化学 | 51篇 |
力学 | 47篇 |
综合类 | 52篇 |
数学 | 3928篇 |
物理学 | 445篇 |
出版年
2023年 | 50篇 |
2022年 | 23篇 |
2021年 | 38篇 |
2020年 | 77篇 |
2019年 | 103篇 |
2018年 | 107篇 |
2017年 | 97篇 |
2016年 | 116篇 |
2015年 | 93篇 |
2014年 | 185篇 |
2013年 | 341篇 |
2012年 | 109篇 |
2011年 | 205篇 |
2010年 | 153篇 |
2009年 | 266篇 |
2008年 | 320篇 |
2007年 | 262篇 |
2006年 | 235篇 |
2005年 | 224篇 |
2004年 | 171篇 |
2003年 | 192篇 |
2002年 | 186篇 |
2001年 | 131篇 |
2000年 | 123篇 |
1999年 | 128篇 |
1998年 | 118篇 |
1997年 | 125篇 |
1996年 | 62篇 |
1995年 | 43篇 |
1994年 | 32篇 |
1993年 | 20篇 |
1992年 | 11篇 |
1991年 | 13篇 |
1990年 | 9篇 |
1989年 | 8篇 |
1988年 | 5篇 |
1987年 | 6篇 |
1986年 | 7篇 |
1985年 | 13篇 |
1984年 | 9篇 |
1983年 | 3篇 |
1982年 | 18篇 |
1981年 | 17篇 |
1980年 | 14篇 |
1979年 | 16篇 |
1978年 | 13篇 |
1977年 | 10篇 |
1976年 | 5篇 |
1973年 | 2篇 |
1970年 | 2篇 |
排序方式: 共有4523条查询结果,搜索用时 15 毫秒
981.
982.
For Lizorkin–Triebel spaces the family of extension operators is constructed which yield a minimal (in order) value of the norm among all possible extensions of a given function defined initially on the interval of an arbitrary small length.The techniques used restrict us to the one-dimensional case and spaces defined via differences of first order. 相似文献
983.
A.G. Ramm 《Journal of Mathematical Analysis and Applications》2007,325(1):490-495
Let A be a linear, closed, densely defined unbounded operator in a Hilbert space. Assume that A is not boundedly invertible. If Eq. (1) Au=f is solvable, and ‖fδ−f‖?δ, then the following results are provided: Problem Fδ(u):=‖Au−fδ‖2+α‖u‖2 has a unique global minimizer uα,δ for any fδ, uα,δ=A*−1(AA*+αI)fδ. There is a function α=α(δ), limδ→0α(δ)=0 such that limδ→0‖uα(δ),δ−y‖=0, where y is the unique minimal-norm solution to (1). A priori and a posteriori choices of α(δ) are given. Dynamical Systems Method (DSM) is justified for Eq. (1). 相似文献
984.
We construct the shift operators and the intertwining operators for the spherical parts of generalized Calogero operators related to classical Coxeter systems. 相似文献
985.
In this paper, we study the rate of convergence for the iterative combinations of a certain family of linear positive operators in terms of higher-order integral modulus of smoothness. We have used the technique of linear approximating method, namely Steklov mean, to prove the main result. In the end, we propose some other sequences of linear positive operators and obtain the recurrence formulae for the central moments, Voronovskaja type asymptotic formulae and error estimations. 相似文献
986.
On the Douglas—Rachford splitting method and the proximal point algorithm for maximal monotone operators 总被引:2,自引:0,他引:2
This paper shows, by means of an operator called asplitting operator, that the Douglas—Rachford splitting method for finding a zero of the sum of two monotone operators is a special case of the proximal point algorithm. Therefore, applications of Douglas—Rachford splitting, such as the alternating direction method of multipliers for convex programming decomposition, are also special cases of the proximal point algorithm. This observation allows the unification and generalization of a variety of convex programming algorithms. By introducing a modified version of the proximal point algorithm, we derive a new,generalized alternating direction method of multipliers for convex programming. Advances of this sort illustrate the power and generality gained by adopting monotone operator theory as a conceptual framework.This paper is drawn largely from the dissertation research of the first author. The dissertation was performed at M.I.T. under the supervision of the second author, and was supported in part by the Army Research Office under grant number DAAL03-86-K-0171, and by the National Science Foundation under grant number ECS-8519058. 相似文献
987.
John Lott 《K-Theory》1992,6(3):191-233
We define the higher eta-invariant of a Dirac-type operator on a nonsimply-connected closed manifold. We discuss its variational properties and how it would fit into a higher index theorem for compact manifolds with boundary. We give applications to questions of positive scalar curvature for manifolds with boundary, and to a Novikov conjecture for manifolds with boundary.Partially supported by the Humboldt Foundation and NSF grant DMS-9101920. 相似文献
988.
We consider two categories with one object, namely the set of all partial functions of one variable from the set of natural numbers into itself; the morphisms are the partial recursive operators in one case, and certain continuous partial mappings in the other case. We show that these categories are recursion categories and we characterize the domains and the complete domains. Some observations are made on a notion of reducibility obtained by using the total morphisms of these categories, and, subsequently, the general recursive operators. 相似文献
989.
A Oblomkov 《Advances in Mathematics》2004,186(1):153-180
We prove that the radial part of the Laplacian on the space of generalized spherical functions on the symmetric space GL(m+n)/GL(m)×GL(n) is the Sutherland differential operator for the root system BCn and the radial parts of the differential operators corresponding to the higher Casimirs yield the integrals of the quantum Calogero-Moser system. It allows us to give a representation theoretical construction for the three parameter family of Heckman-Opdam's Jacobi polynomials for the BCn root system. 相似文献
990.
We discuss the inadequacy of the standard definition of canonical conjugation for a quantum operator having adiscrete spectrum. A different definition is proposed, based on the analogy betweencontinuous anddiscrete translations (or rotations). This definition can be applied to special operators which we calllabel operators. The general form of the conjugate momentum of a label operator is found and the resulting canonical commutation rules are discussed. It is shown that the canonical commutator acts like ac number in itsdomain
I
, but the domain does not coincide with the whole Hilbert space. The properties of the subspace
I
are also discussed. 相似文献