全文获取类型
收费全文 | 1587篇 |
免费 | 49篇 |
国内免费 | 120篇 |
专业分类
化学 | 472篇 |
晶体学 | 1篇 |
力学 | 27篇 |
综合类 | 6篇 |
数学 | 991篇 |
物理学 | 259篇 |
出版年
2024年 | 3篇 |
2023年 | 52篇 |
2022年 | 29篇 |
2021年 | 23篇 |
2020年 | 38篇 |
2019年 | 40篇 |
2018年 | 31篇 |
2017年 | 22篇 |
2016年 | 16篇 |
2015年 | 23篇 |
2014年 | 72篇 |
2013年 | 237篇 |
2012年 | 64篇 |
2011年 | 93篇 |
2010年 | 97篇 |
2009年 | 117篇 |
2008年 | 79篇 |
2007年 | 110篇 |
2006年 | 77篇 |
2005年 | 57篇 |
2004年 | 55篇 |
2003年 | 59篇 |
2002年 | 38篇 |
2001年 | 35篇 |
2000年 | 23篇 |
1999年 | 28篇 |
1998年 | 36篇 |
1997年 | 27篇 |
1996年 | 33篇 |
1995年 | 21篇 |
1994年 | 18篇 |
1993年 | 7篇 |
1992年 | 15篇 |
1991年 | 12篇 |
1990年 | 11篇 |
1989年 | 6篇 |
1988年 | 3篇 |
1987年 | 4篇 |
1986年 | 3篇 |
1985年 | 5篇 |
1984年 | 8篇 |
1982年 | 7篇 |
1981年 | 3篇 |
1980年 | 5篇 |
1979年 | 4篇 |
1978年 | 2篇 |
1977年 | 2篇 |
1974年 | 2篇 |
1973年 | 1篇 |
1970年 | 2篇 |
排序方式: 共有1756条查询结果,搜索用时 46 毫秒
91.
S.S. Gabriyelyan 《Topology and its Applications》2010,157(18):2786-2802
A Polish group G is called a group of quasi-invariance or a QI-group, if there exist a locally compact group X and a probability measure μ on X such that (1) there exists a continuous monomorphism ? from G into X with dense image, and (2) for each g∈X either g∈?(G) and the shift μg is equivalent to μ or g∉?(G) and μg is orthogonal to μ. It is proved that ?(G) is a σ-compact subset of X. We show that there exists a Polish non-locally quasi-convex (and hence nonreflexive) QI-group such that its bidual is not a QI-group. It is proved also that the bidual group of a QI-group may be not a saturated subgroup of X. It is constructed a reflexive non-discrete group topology on the integers. 相似文献
92.
In the setting of ZF, i.e., Zermelo–Fraenkel set theory without the Axiom of Choice (AC), we study partitions of Russell‐sets into sets each with exactly n elements (called n ‐ary partitions), for some integer n. We show that if n is odd, then a Russell‐set X has an n ‐ary partition if and only if |X | is divisible by n. Furthermore, we establish that it is relative consistent with ZF that there exists a Russell‐set X such that |X | is not divisible by any finite cardinal n > 1 (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
93.
This review is a critical overview of the literature on electrochemistry of unsaturated ring-compounds containing bonds between Group 15 and Group 16 elements (principally S and N), including metallacycles. It contains a detailed compilation of measured redox potentials and the conditions under which these were obtained for over 200 compounds. An introduction to the application of solution electrochemistry to this class of compounds is provided, and the relevance of such measurements to materials design is discussed. 相似文献
94.
We propose a perturbation method for determining the (largest) group of invariance of a toric ideal defined in [S. Aoki, A. Takemura, The largest group of invariance for Markov bases and toric ideals, J. Symbolic Comput. 43 (5) (2008) 342–358]. In the perturbation method, we investigate how a generic element in the row space of the configuration defining a toric ideal is mapped by a permutation of the indeterminates. Compared to the proof by Aoki and Takemura which was based on stabilizers of a subset of indeterminates, the perturbation method gives a much simpler proof of the group of invariance. In particular, we determine the group of invariance for a general hierarchical model of contingency tables in statistics, under the assumption that the numbers of the levels of the factors are generic. We prove that it is a wreath product indexed by a poset related to the intersection poset of the maximal interaction effects of the model. 相似文献
95.
Zappa–Szép products arise when an algebraic structure has the property that every element has a unique decomposition as a
product of elements from two given substructures. They may also be constructed from actions of two structures on one another,
satisfying axioms first formulated by G. Zappa, and have a natural interpretation within automata theory. We study Zappa–Szép
products arising from actions of a group and a band, and study the structure of the semigroup that results. When the band
is a semilattice, the Zappa–Szép product is orthodox and ℒ-unipotent. We relate the construction (via automata theory) to
the λ-semidirect product of inverse semigroups devised by Billhardt. 相似文献
96.
97.
We describe the spectrum of the Laplacian for a homogeneous graph acted on by a discrete group. This follows from a more general result which describes the spectrum of a convolution operator on a homogeneous space of a locally compact group. We also prove a version of Harnack inequality for a Schrödinger operator on an invariant homogeneous graph. 相似文献
98.
Anthony To-Ming Lau 《Journal of Functional Analysis》2008,254(10):2513-2533
In this paper, we explore the properties of projections of norm one on general Banach algebras, in particular the relation with conditional expectations for algebras which arise in harmonic analysis. 相似文献
99.
This paper proposes to investigate learning and forgetting effects on the problem of scheduling families of jobs on a single machine to minimize total completion time of jobs. A setup time is incurred whenever the single machine transfers job processing from a family to another family. To analyze the impact of learning and forgetting on this group scheduling problem, we structure three basic models and make some comparisons through computational experiments. The three models, including no forgetting, total forgetting and partial forgetting, assume that the processing time of a job is dependent on its position in a schedule. Some scheduling rules and a lower bound are derived in order to constitute our branch-and-bound algorithm for searching an optimal sequence. In addition, an efficient and simply-structured heuristic is also built to find a near-optimal schedule. 相似文献
100.
邓少强 《数学物理学报(A辑)》2008,28(6):1218-1221
该文证明任何一个两点齐性的 Finsler 流形一定是黎曼流形. 证明过程中作者将泛函分析中经典的Mazur 定理推广到不一定是绝对齐次的 Minkowski 空间上. 相似文献