全文获取类型
收费全文 | 2608篇 |
免费 | 92篇 |
国内免费 | 26篇 |
专业分类
化学 | 1765篇 |
晶体学 | 16篇 |
力学 | 66篇 |
数学 | 484篇 |
物理学 | 395篇 |
出版年
2023年 | 22篇 |
2022年 | 67篇 |
2021年 | 62篇 |
2020年 | 71篇 |
2019年 | 55篇 |
2018年 | 61篇 |
2017年 | 57篇 |
2016年 | 103篇 |
2015年 | 60篇 |
2014年 | 95篇 |
2013年 | 187篇 |
2012年 | 176篇 |
2011年 | 213篇 |
2010年 | 144篇 |
2009年 | 113篇 |
2008年 | 157篇 |
2007年 | 158篇 |
2006年 | 149篇 |
2005年 | 124篇 |
2004年 | 102篇 |
2003年 | 76篇 |
2002年 | 74篇 |
2001年 | 31篇 |
2000年 | 36篇 |
1999年 | 17篇 |
1998年 | 20篇 |
1997年 | 26篇 |
1996年 | 28篇 |
1995年 | 11篇 |
1994年 | 11篇 |
1993年 | 15篇 |
1992年 | 11篇 |
1991年 | 19篇 |
1990年 | 10篇 |
1989年 | 7篇 |
1988年 | 14篇 |
1987年 | 7篇 |
1986年 | 16篇 |
1985年 | 18篇 |
1984年 | 7篇 |
1983年 | 10篇 |
1982年 | 21篇 |
1981年 | 21篇 |
1980年 | 7篇 |
1979年 | 5篇 |
1978年 | 5篇 |
1975年 | 3篇 |
1965年 | 2篇 |
1957年 | 2篇 |
1940年 | 2篇 |
排序方式: 共有2726条查询结果,搜索用时 15 毫秒
1.
2.
Rafael López 《Annals of Global Analysis and Geometry》1997,15(3):201-210
In this paper we study constant mean curvature compact surfaces with two Jordan curves in parallel planes as boundary and we investigate the point at which the surface inherits the symmetries of its boundary. 相似文献
3.
Ilda Abe Rafael E. de Ges Jos L. Fabris Hypolito J. Kalinowski Mrcia Müller Meire C. Fugihara Rosane Falate Barbara W. Diesel Ricardo C. Kamikawachi Carmen L. Barbosa 《Optics and Lasers in Engineering》2003,39(5-6):537-548
In this work, we report production and modelling of both Bragg gratings and rocking filters in high birefringence fibre optics. Bragg gratings are produced by UV (257.0 nm) external interferometric exposition of a frequency-doubled Ar+ ion laser, whereas for rocking filters formation the visible Ar+ ion laser lines in 488.0 and 514.5 nm are used in an internal method. The spectral characteristics due to the birefringence properties are studied through numerical methods and experimental techniques. The spectral responsivity of the structures under temperature changes and stress application is presented. 相似文献
4.
Rafael Tiedra de Aldecoa 《Annales Henri Poincare》2006,7(1):105-124
Although many physical arguments account for using a modified definition of time delay in multichannel-type scattering processes,
one can hardly find rigorous results on that issue in the literature. We try to fill in this gap by showing, both in an abstract
setting and in a short-range case, the identity of the modified time delay and the Eisenbud-Wigner time delay in waveguides.
In the short-range case we also obtain limiting absorption principles, state spectral properties of the total Hamiltonian,
prove the existence of the wave operators and show an explicit formula for the S-matrix. The proofs rely on stationary and commutator methods.
Communicated by Yosi Avron
submitted 12/04/05, accepted 13/05/05 相似文献
5.
Rafael Ortega 《Journal of Dynamics and Differential Equations》1992,4(4):651-665
This paper gives sufficient conditions for the existence of periodic solutions of twist type of a time-dependent differential equation of the second order. The concept of periodic solution of twist type is defined in terms of the corresponding Birkhoff normal form and, in particular, implies that the solution is Lyapunov stable. Some applications to nonlocal problems are given. 相似文献
6.
Currently, most combinatorial optimisation problems have to be solved, if the optimum solution is sought, using general techniques
to explore the space of feasible solutions and, more specifically, through exploratory enumerative procedures in trees and
search graphs. We propose Branch and Win, a general formulation for understanding and synthesising the different tree search
procedures that have been presented in the literature of operations research as well as in that of artificial intelligence.
Several general ideas are also presented, whose application allows designing new hybrid search algorithms, in order to implement
the procedure. 相似文献
7.
Rafael D. Sorkin 《Communications in Mathematical Physics》1988,115(3):421-434
The normal correlation between spin and statistics is shown to be valid for arbitrary kinks, among them theSU(n) Skyrmions forn3. It is assumed in the proof that no gauge-ambiguity attaches to the values of the underlying scalar field, and that conversely each configuration of this field is represented quantum mechanically by a Hilbert subspace of dimension precisely one.Supported in part by NSF Grant No. PHY 83-18350 相似文献
8.
Consider the Schrödinger equation –u+V(x)u=u on the intervalI, whereV(x)0 forxI and where Dirichlet boundary conditions are imposed at the endpoints ofI. We prove the optimal bound
相似文献
9.
10.
Angelo C. Pinto Susan K. Do Prado Raimundo Braz Filho William E. Hull Andras Neszmelyi Gabor Lukacs 《Tetrahedron letters》1982,23(50):5267-5270
With the help of Natural Abundance 13C - 13C Coupling Constants, observed via double quantum coherence, the structural determination of VELLOZIOLONE (1), a new diterpene, has been carried out. 相似文献
|