全文获取类型
收费全文 | 11991篇 |
免费 | 1081篇 |
国内免费 | 970篇 |
专业分类
化学 | 3645篇 |
晶体学 | 29篇 |
力学 | 502篇 |
综合类 | 99篇 |
数学 | 8353篇 |
物理学 | 1414篇 |
出版年
2023年 | 121篇 |
2022年 | 96篇 |
2021年 | 141篇 |
2020年 | 305篇 |
2019年 | 278篇 |
2018年 | 304篇 |
2017年 | 290篇 |
2016年 | 450篇 |
2015年 | 362篇 |
2014年 | 546篇 |
2013年 | 901篇 |
2012年 | 592篇 |
2011年 | 644篇 |
2010年 | 557篇 |
2009年 | 792篇 |
2008年 | 872篇 |
2007年 | 774篇 |
2006年 | 724篇 |
2005年 | 627篇 |
2004年 | 504篇 |
2003年 | 575篇 |
2002年 | 483篇 |
2001年 | 335篇 |
2000年 | 360篇 |
1999年 | 358篇 |
1998年 | 281篇 |
1997年 | 330篇 |
1996年 | 171篇 |
1995年 | 148篇 |
1994年 | 127篇 |
1993年 | 93篇 |
1992年 | 76篇 |
1991年 | 70篇 |
1990年 | 78篇 |
1989年 | 56篇 |
1988年 | 59篇 |
1987年 | 45篇 |
1986年 | 48篇 |
1985年 | 60篇 |
1984年 | 65篇 |
1983年 | 21篇 |
1982年 | 40篇 |
1981年 | 36篇 |
1980年 | 42篇 |
1979年 | 31篇 |
1978年 | 32篇 |
1977年 | 41篇 |
1976年 | 25篇 |
1974年 | 17篇 |
1973年 | 18篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
191.
Ali Ghaffari 《Proceedings Mathematical Sciences》2007,117(2):177-183
In this paper, among other things, we state and prove the mean ergodic theorem for amenable semigroup algebras. 相似文献
192.
Commutators of singular integrals on spaces of homogeneous type 总被引:1,自引:0,他引:1
In this work we prove some sharp weighted inequalities on spaces of homogeneous type for the higher order commutators of singular
integrals introduced by R. Coifman, R. Rochberg and G. Weiss in Factorization theorems for Hardy spaces in several variables,
Ann. Math. 103 (1976), 611–635. As a corollary, we obtain that these operators are bounded on L
p
(w) when w belongs to the Muckenhoupt’s class A
p
, p > 1. In addition, as an important tool in order to get our main result, we prove a weighted Fefferman-Stein type inequality
on spaces of homogeneous type, which we have not found previously in the literature. 相似文献
193.
Pavol Ševera 《Letters in Mathematical Physics》2006,75(3):273-277
We introduce an affine-invariant version of generating functions of symplectic transformations of affine symplectic spaces,
together with a generalization for other symmetric symplectic spaces. The composition of these functions has a nice connection
with the Moyal product. 相似文献
194.
Nicolas Bouleau 《Journal of Functional Analysis》2007,251(1):325-345
The error on a real quantity Y due to the graduation of the measuring instrument may be asymptotically represented, when the graduation is regular and fines down, by a Dirichlet form on R whose square field operator does not depend on the probability law of Y as soon as this law possesses a continuous density. This feature is related to the “arbitrary functions principle” (Poincaré, Hopf). We give extensions of this property to Rd and to the Wiener space for some approximations of the Brownian motion. This gives new approximations of the Ornstein-Uhlenbeck gradient. These results apply to the discretization of some stochastic differential equations encountered in mechanics. 相似文献
195.
Designing a majorization scheme for the recourse function in two-stage stochastic linear programming
José H. Dulá 《Computational Optimization and Applications》1993,1(4):399-414
We discuss issues pertaining to the domination from above of the second-stage recourse function of a stochastic linear program and we present a scheme to majorize this function using a simpler sublinear function. This majorization is constructed using special geometrical attributes of the recourse function. The result is a proper, simplicial function with a simple characterization which is well-suited for calculations of its expectation as required in the computation of stochastic programs. Experiments indicate that the majorizing function is well-behaved and stable. 相似文献
196.
Y. Wardi 《Journal of Optimization Theory and Applications》1990,64(2):399-417
Stochastic algorithms for optimization problems, where function evaluations are done by Monte Carlo simulations, are presented. At each iteratex
i, they draw a predetermined numbern(i) of sample points from an underlying probability space; based on these sample points, they compute a feasible-descent direction, an Armijo stepsize, and the next iteratex
i+1. For an appropriate optimality function , corresponding to an optimality condition, it is shown that, ifn(i) , then (x
i) 0, whereJ is a set of integers whose upper density is zero. First, convergence is shown for a general algorithm prototype: then, a steepest-descent algorithm for unconstrained problems and a feasible-direction algorithm for problems with inequality constraints are developed. A numerical example is supplied. 相似文献
197.
Two main properties of the subgradient mapping of convex functions are transposed for quasiconvex ones. The continuity of the functionxf(x)–1f(x) on the domain where it is defined is deduced from some continuity properties of the normal coneN to the level sets of the quasiconvex functionf. We also prove that, under a pseudoconvexity-type condition, the normal coneN(x) to the set {x:f(x)f(x)} can be expressed as the convex hull of the limits of type {N(x
n)}, where {x
n} is a sequence converging tox and contained in a dense subsetD. In particular, whenf is pseudoconvex,D can be taken equal to the set of points wheref is differentiable.This research was completed while the second author was on a sabbatical leave at the University of Montreal and was supported by a NSERC grant. It has its origin in the doctoral thesis of the first author (Ref. 1), prepared under the direction of the second author.The authors are grateful to an anonymous referee and C. Zalinescu for their helpful remarks on a previous version of this paper. 相似文献
198.
Erik Aurell 《Journal of statistical physics》1990,58(5-6):967-995
I study poles and zeros of zeta functions in one-dimensional maps. Numerical and analytical arguments are given to show that the first pole of one such zeta function is given by the first zero ofanother zeta function: this describes convergence of the calculations of the first zero, which is generally the physically interesting quantity. Some remarks on how these results should generalize to zeta functions of dynamical systems with pruned symbolic dynamics and in higher dimensions follow. 相似文献
199.
A method of using algebraic curves to obtain estimates of critical points accurate enough to identify them as simple algebraic numbers (if that is what they are) is discussed and illustrated with an application to the (q-state Potts model on the triangular lattice for cases of pure two-site interactions and pure three-site interactions. In the latter case the critical point is conjectured to be
. In a similar conjecture for the critical percolation probability on thedirected square lattice,q
c
1/2
(q
c
+3)=2(q
c
+p
c
=1). 相似文献
200.
A. Shapiro 《Journal of Optimization Theory and Applications》1990,66(3):477-487
Various definitions of directional derivatives in topological vector spaces are compared. Directional derivatives in the sense of Gâteaux, Fréchet, and Hadamard are singled out from the general framework of -directional differentiability. It is pointed out that, in the case of finite-dimensional spaces and locally Lipschitz mappings, all these concepts of directional differentiability are equivalent. The chain rule for directional derivatives of a composite mapping is discussed. 相似文献