全文获取类型
收费全文 | 2795篇 |
免费 | 339篇 |
国内免费 | 238篇 |
专业分类
化学 | 258篇 |
晶体学 | 4篇 |
力学 | 119篇 |
综合类 | 41篇 |
数学 | 2192篇 |
物理学 | 758篇 |
出版年
2024年 | 8篇 |
2023年 | 32篇 |
2022年 | 40篇 |
2021年 | 62篇 |
2020年 | 80篇 |
2019年 | 95篇 |
2018年 | 107篇 |
2017年 | 107篇 |
2016年 | 82篇 |
2015年 | 59篇 |
2014年 | 98篇 |
2013年 | 550篇 |
2012年 | 95篇 |
2011年 | 129篇 |
2010年 | 122篇 |
2009年 | 155篇 |
2008年 | 190篇 |
2007年 | 162篇 |
2006年 | 145篇 |
2005年 | 139篇 |
2004年 | 124篇 |
2003年 | 112篇 |
2002年 | 110篇 |
2001年 | 80篇 |
2000年 | 85篇 |
1999年 | 85篇 |
1998年 | 90篇 |
1997年 | 66篇 |
1996年 | 24篇 |
1995年 | 22篇 |
1994年 | 18篇 |
1993年 | 11篇 |
1992年 | 23篇 |
1991年 | 14篇 |
1990年 | 10篇 |
1989年 | 13篇 |
1988年 | 7篇 |
1987年 | 5篇 |
1986年 | 2篇 |
1985年 | 3篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1982年 | 1篇 |
1980年 | 2篇 |
1979年 | 2篇 |
1959年 | 1篇 |
1936年 | 1篇 |
排序方式: 共有3372条查询结果,搜索用时 31 毫秒
101.
Cellular Automaton (CA) based traffic flow models have been extensively studied due to their effectiveness and simplicity in recent years. This paper develops a discrete time Markov chain (DTMC) analytical framework for a Nagel-Schreckenberg and Fukui Ishibashi combined CA model (W^2H traffic flow model) from microscopic point of view to capture the macroscopic steady state speed distributions. The inter-vehicle spacing Maxkov chain and the steady state speed Markov chain are proved to be irreducible and ergodic. The theoretical speed probability distributions depending on the traffic density and stochastic delay probability are in good accordance with numerical simulations. The derived fundamental diagram of the average speed from theoretical speed distributions is equivalent to the results in the previous work. 相似文献
102.
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
103.
We construct the intertwining operator superalgebras and vertex tensor categories for the superconformal unitary minimal models and other related models.
104.
We derive bosonic-type formulas for the characters of
2 coinvariants. 相似文献
105.
106.
We define a set of cell modules for the extended affine Hecke algebra of type A which are parametrised by SLn()-conjugacy classes of pairs (s, N), where s SLn() is semisimple and N is a nilpotent element of the Lie algebra which has at most two Jordan blocks and satisfies Ad(s)·N=q
2
N. When q
2–1, each of these has irreducible head, and the irreducible representations of the affine Hecke algebra so obtained are precisely those which factor through its Temperley–Lieb quotient. When q
2=–1, the above remarks apply to a subset of the cell modules. Using our work on the cellular nature of those quotients, we are able to obtain complete information on the decomposition of the cell modules in all cases, even when q is a root of unity. They turn out to be multiplicity free, and the composition factors may be precisely described in terms of a partial order on the pairs (s, N). These results give explicit formulae for the dimensions of the irreducibles. Assuming our modules are identified with the standard modules earlier defined by Bernstein–Zelevinski, Kazhdan–Lusztig and others, our results may be interpreted as the determination of certain Kazhdan–Lusztig polynomials. [This has now been proved and will appear in a subsequent work of the authors.]The second author thanks the Australian Research Council and the Alexander von Humboldt Stiftung for support and the Universität Bielefeld for hospitality during the preparation of this work. 相似文献
107.
Tamás Szamuely 《K-Theory》1999,18(2):173-179
For a proper smooth variety X defined over a local field k, unramified class field theory investigates the reciprocity map X: SK1(X) ab
1(X) as introduced by S. Saito. We study this map in the case when X is a surface admitting a proper surjection onto a smooth geometrically connected curve C with a smooth conic as generic fibre. Without any assumption on the reduction of C, we prove that X is injective modulo n for all n invertible in k and its cokernel is the same as that of C. 相似文献
108.
Mariusz Rabus Saharon Shelah 《Proceedings of the American Mathematical Society》1999,127(9):2573-2581
For every uncountable cardinal there is a ccc Boolean algebra whose topological density is .
109.
Tom Bohman 《Transactions of the American Mathematical Society》1999,351(3):947-983
In the discrete threshold model for crystal growth in the plane we begin with some set of seed crystals and observe crystal growth over time by generating a sequence of subsets of by a deterministic rule. This rule is as follows: a site crystallizes when a threshold number of crystallized points appear in the site's prescribed neighborhood. The growth dynamics generated by this model are said to be omnivorous if finite and imply . In this paper we prove that the dynamics are omnivorous when the neighborhood is a box (i.e. when, for some fixed , the neighborhood of is . This result has important implications in the study of the first passage time when is chosen randomly with a sparse Bernoulli density and in the study of the limiting shape to which converges.
110.
Let T be a monad over a category A. Then a homotopy structure for A, defined by a cocylinder P : A A, or path-endofunctor, can be lifted to the category A
T
of Eilenberg–Moore algebras over T, provided that P is consistent with T in a natural sense, i.e. equipped with a natural transformation : T P P T satisfying some obvious axioms. In this way, homotopy can be lifted from well-known, basic situations to various categories of algebras for instance, from topological spaces to topological semigroups, or spaces over a fixed space (fibrewise homotopy), or actions of a fixed topological group (equivariant homotopy); from categories to strict monoidal categories; from chain complexes to associative chain algebras. The interest is given by the possibility of lifting the homotopy operations (as faces, degeneracy, connections, reversion, interchange, vertical composition, etc.) and their axioms from A to A
T
, just by verifying the consistency between these operations and : T P P T. When this holds, the structure we obtain on our category of algebras is sufficiently powerful to ensure the main general properties of homotopy. 相似文献