全文获取类型
收费全文 | 378819篇 |
免费 | 2369篇 |
国内免费 | 895篇 |
专业分类
化学 | 176437篇 |
晶体学 | 6125篇 |
力学 | 19707篇 |
综合类 | 1篇 |
数学 | 55047篇 |
物理学 | 124766篇 |
出版年
2021年 | 2284篇 |
2020年 | 2591篇 |
2019年 | 2941篇 |
2018年 | 11424篇 |
2017年 | 12082篇 |
2016年 | 9054篇 |
2015年 | 3907篇 |
2014年 | 5425篇 |
2013年 | 12862篇 |
2012年 | 13590篇 |
2011年 | 22763篇 |
2010年 | 14850篇 |
2009年 | 14930篇 |
2008年 | 20168篇 |
2007年 | 23223篇 |
2006年 | 10594篇 |
2005年 | 14973篇 |
2004年 | 11499篇 |
2003年 | 10764篇 |
2002年 | 8975篇 |
2001年 | 8958篇 |
2000年 | 6928篇 |
1999年 | 5223篇 |
1998年 | 4460篇 |
1997年 | 4286篇 |
1996年 | 4190篇 |
1995年 | 3778篇 |
1994年 | 3691篇 |
1993年 | 3726篇 |
1992年 | 3887篇 |
1991年 | 4111篇 |
1990年 | 3846篇 |
1989年 | 3827篇 |
1988年 | 3796篇 |
1987年 | 3646篇 |
1986年 | 3443篇 |
1985年 | 4572篇 |
1984年 | 4850篇 |
1983年 | 3936篇 |
1982年 | 4166篇 |
1981年 | 4028篇 |
1980年 | 3874篇 |
1979年 | 4046篇 |
1978年 | 4252篇 |
1977年 | 4101篇 |
1976年 | 4149篇 |
1975年 | 3809篇 |
1974年 | 3834篇 |
1973年 | 3888篇 |
1972年 | 2734篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
P. Q. Khanh 《Journal of Optimization Theory and Applications》1995,87(2):359-378
We prove the Kuhn-Tucker sufficient optimality condition, the Wolfe duality, and a modified Mond-Weir duality for vector optimization problems involving various types of invex-convexlike functions. The class of such functins contains many known generalized convex functions. As applications, we demonstrate that, under invex-convexlikeness assumptions, the Pontryagin maximum principle is a sufficient optimality condition for cooperative differential games. The Wolfe duality is established for these games.The author is indebted to the referees and Professor W. Stadler for valuable remarks and comments, which have been used to revise considerably the paper. 相似文献
992.
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
993.
994.
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
995.
996.
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
997.
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
998.
G. I. Mironov 《Physics of the Solid State》2007,49(3):552-561
The anticommutator Green’s functions, correlation functions, and ground-state energies for closed atomic structures that consist of five or six atoms and are structural elements of a fullerene are calculated within the static-fluctuation approximation of the Hubbard model. The results of the calculations are analyzed and compared with the data available in the literature. 相似文献
999.
Laser treatment of bone tissue has already been the subject of many studies to find substitutes for mechanical instruments that are nowadays used in implantology and orthopaedics. Mainly lasers with pulse durations in the μs region have been tested leaving surface features that are not always satisfactory. Therefore, in the present study laser osteotomy has been performed with a 330 fs Yb:glass laser, λ = 1040 nm, at a pulse repetition rate of 1 kHz. For bovine spongiosa, compacta, and cartilage, the ablation thresholds as well as the ablation rates for various pulse energies have been determined. Additionally, quadratic areas have been ablated in bone tissue. The remaining morphology has been analyzed via scanning electron microscopy. Laser ablation has also been performed with an Er, Cr:YSGG laser, λ = 2780 nm, PRR = 20 Hz, τ ~ 50 μs. The results of USPL and Erbium laser ablation are compared. 相似文献
1000.
B. Sun Yu. A. Litvinov P. M. Walker K. Beckert P. Beller F. Bosch D. Boutin C. Brandau L. Chen C. Dimopoulou H. Geissel R. Knöbel C. Kozhuharov J. Kurcewicz S. A. Litvinov M. Mazzocco J. Meng C. Nociforo F. Nolden W. R. Plass C. Scheidenberger M. Steck H. Weick M. Winkler 《The European Physical Journal A - Hadrons and Nuclei》2007,31(3):393-394
A new long-lived isomeric state in the near proton dripline nucleus 125Ce has been identified with Schottky mass spectrometry at GSI. The excitation energy E
* = 103(12)keV and the decay time of 193(1)s have been obtained from a single stored fully ionized 125m
Ce58+ ion. The data implies an E3 transition and a 1/2+ assignment for the spin of the isomer. 相似文献