全文获取类型
收费全文 | 9348篇 |
免费 | 232篇 |
国内免费 | 199篇 |
专业分类
化学 | 889篇 |
晶体学 | 90篇 |
力学 | 85篇 |
综合类 | 23篇 |
数学 | 7331篇 |
物理学 | 1361篇 |
出版年
2023年 | 26篇 |
2022年 | 57篇 |
2021年 | 87篇 |
2020年 | 54篇 |
2019年 | 242篇 |
2018年 | 222篇 |
2017年 | 126篇 |
2016年 | 97篇 |
2015年 | 98篇 |
2014年 | 259篇 |
2013年 | 532篇 |
2012年 | 297篇 |
2011年 | 493篇 |
2010年 | 442篇 |
2009年 | 647篇 |
2008年 | 705篇 |
2007年 | 714篇 |
2006年 | 626篇 |
2005年 | 483篇 |
2004年 | 381篇 |
2003年 | 294篇 |
2002年 | 277篇 |
2001年 | 236篇 |
2000年 | 224篇 |
1999年 | 223篇 |
1998年 | 191篇 |
1997年 | 148篇 |
1996年 | 204篇 |
1995年 | 145篇 |
1994年 | 173篇 |
1993年 | 129篇 |
1992年 | 108篇 |
1991年 | 80篇 |
1990年 | 61篇 |
1989年 | 67篇 |
1988年 | 43篇 |
1987年 | 59篇 |
1986年 | 46篇 |
1985年 | 69篇 |
1984年 | 60篇 |
1983年 | 41篇 |
1982年 | 55篇 |
1981年 | 47篇 |
1980年 | 55篇 |
1979年 | 31篇 |
1978年 | 33篇 |
1977年 | 28篇 |
1976年 | 31篇 |
1974年 | 13篇 |
1973年 | 11篇 |
排序方式: 共有9779条查询结果,搜索用时 140 毫秒
101.
E. K. Sadykov V. V. Arinin G. I. Petrov A. V. Pyataev F. G. Vagizov O. A. Kocharovskaya 《Hyperfine Interactions》2006,167(1-3):893-896
The role of quantum interference (QI) in spectra of the resonant Mössbauer scattering is investigated. As a mechanism ensuring the QI conditions, the radio-frequency (RF) mixing of the spin sublevels of the excited nuclear state is considered. It is shown that QI leads to a significant intensity redistribution of the elastic and Raman scattering. 相似文献
102.
Wen-Rong Dai 《Journal of Differential Equations》2007,235(1):127-165
In this paper, we study the global existence and the asymptotic behavior of classical solution of the Cauchy problem for quasilinear hyperbolic system with constant multiple and linearly degenerate characteristic fields. We prove that the global C1 solution exists uniquely if the BV norm of the initial data is sufficiently small. Based on the existence result on the global classical solution, we show that, when the time t tends to the infinity, the solution approaches a combination of C1 traveling wave solutions. Finally, we give an application to the equation for time-like extremal surfaces in the Minkowski space-time R1+n. 相似文献
103.
Hubert de Fraysseix 《Discrete Applied Mathematics》2007,155(9):1079-1095
Using a general resolution of barycentric systems we give a generalization of Tutte's theorem on convex drawing of planar graphs. We deduce a characterization of the edge coverings into pairwise non-crossing paths which are stretchable: such a system is stretchable if and only if each subsystem of at least two paths has at least three free vertices (vertices of the outer face of the induced subgraph which are internal to none of the paths of the subsystem). We also deduce that a contact system of pseudo-segments is stretchable if and only if it is extendible. 相似文献
104.
The 57Fe Mössbauer technique has been used to investigate the effect of zinc oxide substitution in (25???x)MnO–xZnO–15Fe2O3–60B2O3 glass system (x?=?0, 5, 10, 15 and 20 mol% of ZnO ). Mössbauer absorption spectra for all the samples recorded at room temperature suggest the existence of the two paramagnetic quadrupole doublets. The observed variations in hyperfine parameters have been explained on the basis of cations distribution and exchange interaction at the lattice sites and it is concluded that B–B interaction increases while the metal–metal interaction decreases due to replacement of manganese oxide by zinc oxide. These results suggest that the present glass system exhibits a paramagnetic behaviour that changes towards the weak paramagnetic when manganese oxide was replaced with zinc oxide. 相似文献
105.
We give general conditions on a generator of a C0-semigroup (resp. of a C0-resolvent) on Lp(E,μ), p ≥ 1, where E is an arbitrary (Lusin) topological space and μ a σ-finite measure on its Borel σ-algebra, so that it generates a sufficiently
regular Markov process on E. We present a general method how these conditions can be checked in many situations. Applications to solve stochastic differential
equations on Hilbert space in the sense of a martingale problem are given.
Dedicated to Giuseppe Da Prato on the occasion of his 70th birthday 相似文献
106.
The problem of analytic representation of integrable CR functions on hypersurfaces with singularities is treated. The nature of singularities does not matter while the set of singularities
has surface measure zero. For simple singularities like cuspidal points, edges, corners, etc., also the behaviour of representing
analytic functions near singular points is studied.
Received: 8 December 2000; in final form: 24 June 2001/Published online: 1 February 2002 相似文献
107.
部分相干光束通过硬边光阑的推广光束传输M2因子 总被引:2,自引:2,他引:0
给出部分相干光通过硬边光阑后的强度二阶矩的计算公式,由此可得到部分相干光通过硬边光阑后的推广光束传输M^2因子。以部分相干高斯-谢尔模型光束为例,推导出相应的M^2因子,并作了数值计算和分析讨论。 相似文献
108.
Global Existence and Exponential Stability of Smooth Solutions to a Full Hydrodynamic Model to Semiconductors 总被引:1,自引:0,他引:1
We study a full hydrodynamic semiconductor model in multi-space dimension. The global existence of smooth solutions is established
and the exponential stability of the solutions as is investigated.
Received November 14, 2000; in revised form March 25, 2002 Published online August 5, 2002 相似文献
109.
Summary. The perfectly matched layer (PML) is an efficient tool to simulate propagation phenomena in free space on unbounded domain.
In this paper we consider a new type of absorbing layer for Maxwell's equations and the linearized Euler equations which is
also valid for several classes of first order hyperbolic systems. The definition of this layer appears as a slight modification
of the PML technique. We show that the associated Cauchy problem is well-posed in suitable spaces. This theory is finally
illustrated by some numerical results. It must be underlined that the discretization of this layer leads to a new discretization
of the classical PML formulation.
Received May 5, 2000 / Published online November 15, 2001 相似文献
110.
Cyrille Ospel 《Journal of Pure and Applied Algebra》2002,173(3):315-337
For a commutative algebra the shuffle product is a morphism of complexes. We generalize this result to the quantum shuffle product, associated to a class of non-commutative algebras (for example all the Hopf algebras). As a first application we show that the Hochschild-Serre identity is the dual statement of our result. In particular, we extend this identity to Hopf algebras. Secondly, we clarify the construction of a class of quasi-Hopf algebras. 相似文献