全文获取类型
收费全文 | 6487篇 |
免费 | 879篇 |
国内免费 | 463篇 |
专业分类
化学 | 2354篇 |
晶体学 | 5篇 |
力学 | 583篇 |
综合类 | 112篇 |
数学 | 2634篇 |
物理学 | 2141篇 |
出版年
2024年 | 25篇 |
2023年 | 95篇 |
2022年 | 158篇 |
2021年 | 146篇 |
2020年 | 195篇 |
2019年 | 197篇 |
2018年 | 200篇 |
2017年 | 253篇 |
2016年 | 236篇 |
2015年 | 242篇 |
2014年 | 279篇 |
2013年 | 533篇 |
2012年 | 404篇 |
2011年 | 406篇 |
2010年 | 329篇 |
2009年 | 358篇 |
2008年 | 417篇 |
2007年 | 444篇 |
2006年 | 368篇 |
2005年 | 355篇 |
2004年 | 287篇 |
2003年 | 282篇 |
2002年 | 263篇 |
2001年 | 182篇 |
2000年 | 216篇 |
1999年 | 171篇 |
1998年 | 112篇 |
1997年 | 109篇 |
1996年 | 107篇 |
1995年 | 78篇 |
1994年 | 55篇 |
1993年 | 44篇 |
1992年 | 53篇 |
1991年 | 56篇 |
1990年 | 34篇 |
1989年 | 26篇 |
1988年 | 15篇 |
1987年 | 21篇 |
1986年 | 14篇 |
1985年 | 9篇 |
1984年 | 10篇 |
1983年 | 6篇 |
1982年 | 11篇 |
1981年 | 7篇 |
1980年 | 5篇 |
1979年 | 4篇 |
1977年 | 2篇 |
1971年 | 2篇 |
1957年 | 2篇 |
1936年 | 2篇 |
排序方式: 共有7829条查询结果,搜索用时 109 毫秒
991.
We study the schedule of shuttle buses in the transportation system controlled by capacity. The bus schedule is closely related to the dynamic motion of buses. We present the nonlinear-map model for the dynamics of shuttle buses. The motion of shuttle buses depends on the inflow rate. The dependence of the fixed points on the inflow is derived. The dynamic transitions occur with increasing the value of inflow rate. At the dynamic transition point, the motion of buses changes from a stable state to an unstable state and vice versa. The shuttle buses display periodic, quasi-periodic, and chaotic motions in the unstable state. In the unstable state, the number of riding passengers fluctuates complexly with varying trips. The bus schedule is governed by the complex motion of buses. 相似文献
992.
Mateja Grašič 《Linear and Multilinear Algebra》2013,61(8):1007-1022
We show that the Lie algebra ? of skew-symmetric matrices with respect to either transpose or symplectic involution is zero product determined. This means that every bilinear map {·,·} from ? × ? into a vector space X is of the form {x, y} = T ([x, y]) for some linear map T provided that the following condition is fulfilled: [x, y] = 0 implies {x, y} = 0. 相似文献
993.
994.
We study the dynamical invariant for dissipative three coupled oscillators mainly from the quantum mechanical point of view. It is known that there are many advantages of the invariant quantity in elucidating mechanical properties of the system. We use such a property of the invariant operator in quantizing the system in this work. To this end, we first transform the invariant operator to a simple one by using a unitary operator in order that we can easily manage it. The invariant operator is further simplified through its diagonalization via three-dimensional rotations parameterized by three Euler angles. The coupling terms in the quantum invariant are eventually eliminated thanks to such a diagonalization. As a consequence, transformed quantum invariant is represented in terms of three independent simple harmonic oscillators which have unit masses. Starting from the wave functions in the transformed system, we have derived the full wave functions in the original system with the help of the unitary operators. 相似文献
995.
996.
997.
A new iterative method for finding a zero of m-accretive operators is proposed. This method, involving a so-called perturbed mapping, provides a way to construct sunny nonexpansive retractions. Several strong convergence theorems for this method are established in a Banach space that is either uniformly smooth or reflexive with a weakly continuous duality map. 相似文献
998.
999.
Noelle Antony 《代数通讯》2013,41(11):4043-4056
ABSTRACT Baez and Birman introduced the singular braid monoid on n + 1 strings, 𝒮B n+1, which Birman uses in understanding knot invariants. 𝒮? n+1 is the type A n case of an infinite class of monoids known as singular Artin monoids and denoted by 𝒮G M for a Coxeter matrix M. Birman conjectured, and Paris proved, that 𝒮B n+1 embeds in the complex algebra of the braid group under the desingularisation map or Vassiliev homomorphism, η. In effect, Birman's conjecture generalizes to arbitrary types since, as noted by Corran, the Vassiliev homomorphism from 𝒮G M to the algebra of the corresponding Artin group is well defined. We deduce general combinatorial results regarding divisibility in positive singular Artin monoids, and when M is of finite type, a well-defined positive form for 𝒮G M is produced. These facts are then invoked to infer that, when M is of finite type, η is injective on pairs of words such that a common multiple exists for their positive form. 相似文献
1000.
R. Donner 《The European Physical Journal B - Condensed Matter and Complex Systems》2008,63(3):349-361
Networks of interacting components are a class of complex systems that has attracted considerable interest over the last decades.
In particular, if the dynamics of the autonomous components is characterised by an oscillatory behaviour, different types
of synchronisation can be observed in dependence on the type and strength of interactions. In this contribution, we study
the transition from non-synchronised to synchronised phase dynamics in complex networks. The most common approach to quantify
the degree of phase synchronisation in such systems is the consideration of measures of phase coherence which are averaged
over all pairs of interacting components. However, this approach implicitly assumes a spatially homogeneous synchronisation process,
which is typically not present in complex networks. As a potential alternative, two novel methods of multivariate phase synchronisation analysis are considered: synchronisation cluster analysis (SCA) and the linear variance decay (LVD)
dimension method. The strengths and weaknesses of the traditional as well as both new approaches are briefly illustrated for
a Kuramoto model with long-range coupling. As a practical application, we study how spatial heterogeneity influences the transition
to phase synchronisation in traffic networks where intersecting material flows are subjected to a self-organised decentralised
control. We find that the network performance and the degree of phase synchronisation are closely related to each other and
decrease significantly in the case of structural heterogeneities. The influences of the different parameters of our control
approach on the synchronisation process are systematically studied, yielding a sequence of Arnold tongues which correspond
to different locking modes. 相似文献