全文获取类型
收费全文 | 17533篇 |
免费 | 427篇 |
国内免费 | 320篇 |
专业分类
化学 | 1217篇 |
晶体学 | 42篇 |
力学 | 207篇 |
综合类 | 20篇 |
数学 | 15510篇 |
物理学 | 1284篇 |
出版年
2023年 | 24篇 |
2022年 | 40篇 |
2021年 | 32篇 |
2020年 | 65篇 |
2019年 | 492篇 |
2018年 | 592篇 |
2017年 | 280篇 |
2016年 | 171篇 |
2015年 | 203篇 |
2014年 | 561篇 |
2013年 | 1159篇 |
2012年 | 643篇 |
2011年 | 1123篇 |
2010年 | 980篇 |
2009年 | 1265篇 |
2008年 | 1339篇 |
2007年 | 1289篇 |
2006年 | 1022篇 |
2005年 | 658篇 |
2004年 | 553篇 |
2003年 | 512篇 |
2002年 | 367篇 |
2001年 | 371篇 |
2000年 | 362篇 |
1999年 | 429篇 |
1998年 | 376篇 |
1997年 | 319篇 |
1996年 | 411篇 |
1995年 | 411篇 |
1994年 | 396篇 |
1993年 | 317篇 |
1992年 | 197篇 |
1991年 | 104篇 |
1990年 | 75篇 |
1989年 | 92篇 |
1988年 | 71篇 |
1987年 | 59篇 |
1986年 | 60篇 |
1985年 | 108篇 |
1984年 | 115篇 |
1983年 | 84篇 |
1982年 | 113篇 |
1981年 | 98篇 |
1980年 | 67篇 |
1979年 | 55篇 |
1978年 | 62篇 |
1977年 | 52篇 |
1976年 | 40篇 |
1975年 | 22篇 |
1974年 | 19篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
61.
In this paper we investigate the electrostatic problem of determining conductivity profiles from the knowledge of boundary
currents and voltages. We obtain an improved estimate for the voltage potential of a two-dimensional conductor having finitely
many circular inclusions and piecewise constant conductivity profile. We derive an asymptotic expansion for the voltage potential
in terms of the reference voltage potential and the location, size, and conductivity of the inhomogeneities. This representation
is used to formulate the nonlinear least squares problem for estimating the location and size of the inhomogeneities. Required
boundary data for the voltage potential are generated numerically by solving a system of integral equations. Computational
experiments are presented to demonstrate the effectiveness of our identification procedure. 相似文献
62.
63.
R. M. Dudley 《Probability Theory and Related Fields》1994,100(2):175-189
Summary In a separable metric space, if two Borel probability measures (laws) are nearby in a suitable metric, then there exist random variables with those laws which are nearby in probability. Specifically, by a well-known theorem of Strassen, the Prohorov distance between two laws is the infimum of Ky Fan distances of random variables with those laws. The present paper considers possible extensions of Strassen's theorem to two random elements one of which may be (compact) set-valued and/or non-measurable. There are positive results in finite-dimensional spaces, but with factors depending on the dimension. Examples show that such factors cannot entirely be avoided, so that the extension of Strassen's theorem to the present situation fails in infinite dimensions.This research was partially supported by a Guggenheim Fellowship, by National Science Foundation grant DMS 8505550 at MSRI-Berkeley, and other NSF grants 相似文献
64.
Summary As a continuation of the study by Herbst and Pitt (1991), this note presents two criteria. The first one is on the order-preservation for two (may be different) multidimensional diffusion processes. The second one is on the preservation of positive correlations for a diffusion process.Research supported in part by the Ying-Tung Fok Educational Foundation and the National Natural Science Foundation of China 相似文献
65.
Dmitrii S. Silvestrov 《Acta Appl Math》1994,34(1-2):109-124
Coupling procedures for Markov renewal processes are described. Applications to ergodic theorems for processes with semi-Markov switchings are considered.This paper was partly prepared with the support of NFR Grant F-UP 10257-300. 相似文献
66.
Partially supportted by Grant MM-22/1991 of MESC 相似文献
67.
Asymptotics in the random assignment problem 总被引:1,自引:0,他引:1
David Aldous 《Probability Theory and Related Fields》1992,93(4):507-534
Summary We show that, in the usual probabilistic model for the random assignment problem, the optimal cost tends to a limit constant in probability and in expectation. The method involves construction of an infinite limit structure, in terms of which the limit constant is defined. But we cannot improve on the known numerical bounds for the limit.Research supported by NSF Grant MCS90-01710 相似文献
68.
Non-local approximation of the Mumford-Shah functional 总被引:3,自引:0,他引:3
The Mumford-Shah functional, introduced to study image segmentation problems, is approximated in the sense of -convergence by a sequence of non-local integral functionals.
Received June 6, 1996 / Accepted July 11, 1996 相似文献
69.
Yuri Borovskikh 《Acta Appl Math》1994,35(3):213-298
U-statistics in Banach spaces are considered and thoroughly investigated. The martingale structure, estimates of moments, the law of large numbers, the central limit theorem, the invariance principle, estimates of the rate of convergence, and large deviations are established 相似文献
70.
Shuguang Wang 《Geometriae Dedicata》1995,57(2):207-215
We classify, in terms of simple algebraic equations, the fixed point sets of the moduli space of stable bundles over genus 2 curves with anti-holomorphic involutions.Research supported by SRF of University of Missouri. 相似文献