全文获取类型
收费全文 | 297156篇 |
免费 | 1975篇 |
国内免费 | 609篇 |
专业分类
化学 | 133708篇 |
晶体学 | 4662篇 |
力学 | 15880篇 |
综合类 | 5篇 |
数学 | 45759篇 |
物理学 | 99726篇 |
出版年
2021年 | 1655篇 |
2020年 | 1797篇 |
2019年 | 2000篇 |
2018年 | 10897篇 |
2017年 | 11683篇 |
2016年 | 7565篇 |
2015年 | 3107篇 |
2014年 | 3732篇 |
2013年 | 9202篇 |
2012年 | 11346篇 |
2011年 | 20522篇 |
2010年 | 12922篇 |
2009年 | 12877篇 |
2008年 | 18036篇 |
2007年 | 21573篇 |
2006年 | 7908篇 |
2005年 | 13439篇 |
2004年 | 9669篇 |
2003年 | 8928篇 |
2002年 | 6861篇 |
2001年 | 6570篇 |
2000年 | 5228篇 |
1999年 | 3832篇 |
1998年 | 3081篇 |
1997年 | 3064篇 |
1996年 | 2960篇 |
1995年 | 2708篇 |
1994年 | 2552篇 |
1993年 | 2412篇 |
1992年 | 2757篇 |
1991年 | 2738篇 |
1990年 | 2666篇 |
1989年 | 2477篇 |
1988年 | 2536篇 |
1987年 | 2532篇 |
1986年 | 2355篇 |
1985年 | 3051篇 |
1984年 | 3315篇 |
1983年 | 2717篇 |
1982年 | 2884篇 |
1981年 | 2862篇 |
1980年 | 2714篇 |
1979年 | 2818篇 |
1978年 | 2926篇 |
1977年 | 2846篇 |
1976年 | 2952篇 |
1975年 | 2719篇 |
1974年 | 2690篇 |
1973年 | 2852篇 |
1972年 | 1795篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
961.
M. F. Horodnii 《Ukrainian Mathematical Journal》2007,59(8):1130-1136
We prove that the operator d/dt + A constructed on the basis of a sectorial operator A with spectrum in the right half-plane of ℂ is continuously invertible in the Sobolev spaces W
p
1
(ℝ, D
α), α ≥ 0. Here, D
α is the domain of definition of the operator A
α and the norm in D
α is the norm of the graph of A
α.
__________
Translated from Ukrains’kyi Matematychnyi Zhurnal, Vol. 59, No. 8, pp. 1020–1025, August, 2007. 相似文献
962.
V. G. Pimenov 《Proceedings of the Steklov Institute of Mathematics》2007,259(2):S201-S212
This paper deals with constructing multistep numerical methods for differential delay equations under additional algebraic constraints. Theorems on the orders of convergence of these methods are proved both for functional-differential equations with algebraic constraints and for singular functional-differential equations. 相似文献
963.
We study the connection between universal central extensions in the categories of precrossed and crossed modules. They are compared with several kinds of universal central extensions in the categories of groups, epimorphisms of groups, groups with operators and modules over a group. We study the relationship between the homologies defined in these categories. Applications to relative algebraic K-theory are also obtained. 相似文献
964.
Controllability of Functional Integro-Differential Inclusions with an Unbounded Delay 总被引:1,自引:0,他引:1
In this paper, a sufficient condition is established for the controllability of neutral functional integro-differential inclusions
with an unbounded delay in Banach spaces. The approach used is a fixed-point theorem for condensing maps due to Martelli and
the theory of analytic semigroup of linear operators.
Communicated by F. Zirilli
Research supported by NNSF of China, by the Teaching and Research Award Program for Outstanding Young Teachers in Higher Education
Institutions of the Ministry of Education of China, and by the Qing Lan Talent Engineering Fund QL-05-164 of Lanzhou Jiaotong
University. The authors are grateful to Professor F. Zirilli and two anonymous referees for valuable suggestions improving
this paper. 相似文献
965.
966.
A. V. Gavrilov 《Siberian Mathematical Journal》2007,48(1):56-61
We study the double exponential map which is a composition of a special form of two exponential maps on a manifold with connection. We relate this map and the composition of covariant derivations as well as the composition of pseudodifferential operators on these manifolds. 相似文献
967.
968.
E. G. Emel’yanov 《Journal of Mathematical Sciences》2007,143(3):3077-3089
The paper considers the problem on extremal decomposition of a multiply connected domain G ⊂ ℂ in the case where the associated
quadratic differential is a perfect square. It is shown that in the case considered, the value of the functional for this
extremal decomposition is the least one in a certain class of decompositions. Bibliography: 10 titles.
Dedicated to the 100th anniversary of G. M. Goluzin’s birthday
__________
Translated from Zapiski Nauchnykh Seminarov POMI, Vol. 337, 2006, pp. 113–133. 相似文献
969.
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
970.
L. E. Shchebelina 《Technical Physics》2007,52(1):137-138
Analytical expressions for the mathematical expectation and dispersion of the time of flight of a nonrelativistic charged particle through a multielectrode system consisting of parallel grids are derived. These expressions can be useful in design optimization, for example, of plasma-confining grid systems and time-of-flight mass spectrometers. 相似文献