全文获取类型
收费全文 | 2550篇 |
免费 | 265篇 |
国内免费 | 206篇 |
专业分类
化学 | 217篇 |
晶体学 | 6篇 |
力学 | 408篇 |
综合类 | 66篇 |
数学 | 1469篇 |
物理学 | 855篇 |
出版年
2023年 | 18篇 |
2022年 | 32篇 |
2021年 | 38篇 |
2020年 | 60篇 |
2019年 | 43篇 |
2018年 | 49篇 |
2017年 | 58篇 |
2016年 | 63篇 |
2015年 | 53篇 |
2014年 | 132篇 |
2013年 | 208篇 |
2012年 | 126篇 |
2011年 | 175篇 |
2010年 | 119篇 |
2009年 | 160篇 |
2008年 | 173篇 |
2007年 | 179篇 |
2006年 | 153篇 |
2005年 | 125篇 |
2004年 | 123篇 |
2003年 | 121篇 |
2002年 | 112篇 |
2001年 | 79篇 |
2000年 | 82篇 |
1999年 | 72篇 |
1998年 | 59篇 |
1997年 | 65篇 |
1996年 | 51篇 |
1995年 | 45篇 |
1994年 | 34篇 |
1993年 | 25篇 |
1992年 | 27篇 |
1991年 | 22篇 |
1990年 | 14篇 |
1989年 | 16篇 |
1988年 | 17篇 |
1987年 | 7篇 |
1986年 | 11篇 |
1985年 | 13篇 |
1984年 | 10篇 |
1983年 | 7篇 |
1982年 | 9篇 |
1981年 | 5篇 |
1980年 | 7篇 |
1979年 | 4篇 |
1978年 | 4篇 |
1977年 | 3篇 |
1976年 | 3篇 |
1972年 | 2篇 |
1959年 | 2篇 |
排序方式: 共有3021条查询结果,搜索用时 31 毫秒
111.
建立了随机事元之间的关系事元,研究随机事件之间的关系.利用关系元刻画了两个随机事件之间的关系.运用可拓变换初步研究了二维离散型随机变量的分布律和边缘分布律的传导分布. 相似文献
112.
This paper deals with the discontinuous Galerkin (DG) methods for delay differential equations.By an orthogonal analysis in each element,the superconvergence re... 相似文献
113.
Divergence-free wavelets are successfully applied to numerical solutions of Navier-Stokes equation and to analysis of incompressible
flows. They closely depend on a pair of one-dimensional wavelets with some differential relations. In this paper, we point
out some restrictions of those wavelets and study scaling functions with the differential relation; Wavelets and their duals
are discussed; In addition to the differential relation, we are particularly interested in a class of examples with the interpolatory
property; It turns out there is a connection between our examples and Micchelli’s work. 相似文献
114.
From the Heisenberg uncertainty relation in conjunction with partial transposition, we derive a class of inequalities for detecting entanglements in four-mode states. The sufficient conditions for bipartite entangled states are presented. We also discuss the generalization of the entanglement conditions via the Schrödinger-Robertson indeterminacy relation, which are in general stronger than those based on the Heisenberg uncertainty relation. 相似文献
115.
We have theoretically investigated the energy band structures of two typical magnetic superlattices formed by perpendicular or parallel magnetization ferromagnetic stripes periodically deposited on a two-dimensional electron gas (2DEG), where the magnetic profile in the perpendicular magnetization is of inversion anti-symmetry, but of inversion symmetry in parallel magnetization, respectively. We have shown that the energy bands of perpendicular magnetization display the spin-splitting and transverse wave-vector symmetry, while the energy bands of the parallel magnetization exhibit spin degeneration and transverse wave-vector asymmetry. These distinguishing spin-dependent and transverse wave-vector asymmetry features are essential for future spintronics devices applications. 相似文献
116.
117.
M. Petrich 《Acta Mathematica Hungarica》2002,97(4):303-322
The relation in the title is S defined by
on an arbitrary semigroup. We investigate antisymmetry of S by means of a (minimal) family whose members can not appear as subsemigroups. Transitivity of S is characterized similarly by means of the family and homomorphic images of a certain semigroup. We study the transfer of certain properties of a monoid T and the Bruck semigroup B(T,) over T. The paper concludes with a consideration of certain properties of the relation S on inverse semigroups. 相似文献
118.
Motivated by the theory of phase transition dynamics, we consider one-dimensional, nonlinear hyperbolic conservation laws with nonconvex flux-function containing vanishing nonlinear diffusive-dispersive terms. Searching for traveling wave solutions, we establish general results of existence, uniqueness, monotonicity, and asymptotic behavior. In particular, we investigate the properties of the traveling waves in the limits of dominant diffusion, dominant dispersion, and asymptotically small or large shock strength. As the diffusion and dispersion parameters tend to 0, the traveling waves converge to shock wave solutions of the conservation law, which either satisfy the classical Oleinik entropy criterion or are nonclassical undercompressive shocks violating it. 相似文献
119.
Zeph A. Landau 《Geometriae Dedicata》2002,95(1):183-214
An inclusion of II
1 factors NM of finite index has as an invariant, a double sequence of finite-dimensional algebras known as the standard invariant. Planar algebras were introduced by V. Jones as a geometric tool for computing standard invariants of existing subfactors as well as generating standard invariants for new subfactors. In this paper we define a class of planar algebras, termed exchange relation planar algebras, that provides a general framework for understanding several classes of known subfactor inclusions: the Fuss–Catalan algebras (i.e. those coming from the presence of intermediate subfactors) and all depth 2 subfactors. In addition, we present a new class of planar algebras (and thus a new class of subfactors) coming from automorphism subgroups of finite groups. 相似文献
120.
This paper presents complete solutions of the stationary distributions of buffer occupancy and buffer content of a fluid queue driven by an M/M/1 queue. We assume a general boundary condition when compared to the model discussed in Virtamo and Norros [Queueing Systems 16 (1994) 373–386] and Adan and Resing [Queueing Systems 22 (1996) 171–174]. We achieve the required solutions by transforming the underlying system of differential equations using Laplace transforms to a system of difference equations leading to a continued fraction. This continued fraction helps us to find complete solutions. We also obtain the buffer content distribution for this fluid model using the method of Sericola and Tuffin [Queueing Systems 31 (1999) 253–264]. 相似文献