全文获取类型
收费全文 | 10359篇 |
免费 | 429篇 |
国内免费 | 88篇 |
专业分类
化学 | 7135篇 |
晶体学 | 93篇 |
力学 | 267篇 |
综合类 | 1篇 |
数学 | 1740篇 |
物理学 | 1640篇 |
出版年
2023年 | 81篇 |
2022年 | 121篇 |
2021年 | 193篇 |
2020年 | 210篇 |
2019年 | 250篇 |
2018年 | 158篇 |
2017年 | 159篇 |
2016年 | 384篇 |
2015年 | 288篇 |
2014年 | 320篇 |
2013年 | 603篇 |
2012年 | 607篇 |
2011年 | 653篇 |
2010年 | 453篇 |
2009年 | 404篇 |
2008年 | 586篇 |
2007年 | 630篇 |
2006年 | 494篇 |
2005年 | 547篇 |
2004年 | 440篇 |
2003年 | 350篇 |
2002年 | 336篇 |
2001年 | 162篇 |
2000年 | 144篇 |
1999年 | 96篇 |
1998年 | 103篇 |
1997年 | 109篇 |
1996年 | 113篇 |
1995年 | 93篇 |
1994年 | 84篇 |
1993年 | 100篇 |
1992年 | 78篇 |
1991年 | 79篇 |
1990年 | 74篇 |
1989年 | 64篇 |
1988年 | 51篇 |
1987年 | 55篇 |
1986年 | 69篇 |
1985年 | 103篇 |
1984年 | 101篇 |
1983年 | 79篇 |
1982年 | 69篇 |
1981年 | 72篇 |
1980年 | 68篇 |
1979年 | 64篇 |
1978年 | 68篇 |
1977年 | 41篇 |
1976年 | 40篇 |
1975年 | 50篇 |
1974年 | 54篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
72.
73.
Let be a bounded, connected linearly convex set in with boundary. We show that the maximal ideal (both in ) and ) consisting of all functions vanishing at is generated by the coordinate functions .
Received: 2 July 2001; in final form: 26 September 2001 / Published online: 28 February 2002 相似文献
74.
Jan J. Slawianowski 《General Relativity and Gravitation》2003,35(5):965-966
75.
Jan Andres Karel Pastor Pavla Šnyrychová 《Journal of Fixed Point Theory and Applications》2007,2(1):153-170
A multivalued version of Sharkovskiĭ’s theorem is formulated for M-maps on linear continua and, more generally, for triangular M-maps on a Cartesian product of linear continua. This improves the main result of [AP1] in the sense that our multivalued
analogue holds with at most two exceptions. A further specification requires some additional restrictions. For instance, 3-
orbits of m-maps imply the existence of k-orbits for all
k ? \mathbbNk \in {\mathbb{N}}
, except possibly for
k ?k \in
{4, 6}. It is also shown that, on every connected linearly ordered topological space, an M-map with orbits of all periods can always be constructed. This demonstrates that Baldwin’s classification of linear continua
in terms of admissible periods [Ba] is useless for multivalued maps. 相似文献
76.
We present a construction which shows that some special continua do not have the nonwandering-eventually-periodic property. The construction applies e.g. to the topologist's sin curve and to the harmonic fan. 相似文献
77.
We investigate traces of functions, belonging to a class of functions with dominating mixed smoothness in ℝ3, with respect to planes in oblique position. In comparison with the classical theory for isotropic spaces a few new phenomenona
occur. We shall present two different approaches. One is based on the use of the Fourier transform and restricted to p = 2. The other one is applicable in the general case of Besov-Lizorkin-Triebel spaces and based on atomic decompositions. 相似文献
78.
The stoichiometric reactions of trimethylaluminum with 2,6‐(MeOCH2)2C6H3OH (LH) revealed compounds L3Al ( 1 ) and L2AlMe ( 2 ). On the other hand reaction of 1 equiv. of LH with trimethylaluminum did not lead to the formation of complex LAlMe2 ( 3 ), rather 2 together with Me3Al were observed as a result of a disproportionation of 3 . Compounds 1 and 2 were characterized by elemental analysis, 1H and 13C NMR spectroscopy and in the case of 1 by X‐ray diffraction. Derivative 2 underwent transmetalation with Ph3SnOH, giving LSnPh3 ( 4 ) as the result of a migration of ligand L from the aluminum to the tin atom. The identity of 4 was established by elemental analysis, 1H, 13C and 119Sn NMR spectroscopy and 1H, 119Sn HMBC experiments. The system 2 and B(C6F5)3 in a 1:1 molar ratio was shown to be active in the polymerization of propylene oxide and ε‐caprolactone. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
79.
Daniel Král’ Jan Kratochvíl Andrzej Proskurowski Heinz-Jürgen Voss 《Discrete Applied Mathematics》2006,154(4):660-672
A mixed hypergraph is a triple (V,C,D) where V is its vertex set and C and D are families of subsets of V, called C-edges and D-edges, respectively. For a proper coloring, we require that each C-edge contains two vertices with the same color and each D-edge contains two vertices with different colors. The feasible set of a mixed hypergraph is the set of all k's for which there exists a proper coloring using exactly k colors. A hypergraph is a hypertree if there exists a tree such that the edges of the hypergraph induce connected subgraphs of the tree.We prove that feasible sets of mixed hypertrees are gap-free, i.e., intervals of integers, and we show that this is not true for precolored mixed hypertrees. The problem to decide whether a mixed hypertree can be colored by k colors is NP-complete in general; we investigate complexity of various restrictions of this problem and we characterize their complexity in most of the cases. 相似文献
80.
Applying a Lindemann like criterion obtained previously by Kierfeld et al. [J. Kierfeld, T. Nattermann, T. Hwa, Phys. Rev. B 55 (1997) 626], we estimate the magnetic field and temperature for a high-Tc superconductor, at which a topologically ordered vortex glass phase becomes unstable with respect to a disorder-induced formation of dislocations. The employed criterion is shown to be equivalent to a conventional phenomenological Lindemann criterion including the values for the numerical factors, i.e., for the Lindemann number. The positional correlation length of the topologically ordered vortex glass is calculated. 相似文献