全文获取类型
收费全文 | 5910篇 |
免费 | 338篇 |
国内免费 | 612篇 |
专业分类
化学 | 1601篇 |
晶体学 | 14篇 |
力学 | 142篇 |
综合类 | 60篇 |
数学 | 4429篇 |
物理学 | 614篇 |
出版年
2024年 | 5篇 |
2023年 | 65篇 |
2022年 | 96篇 |
2021年 | 105篇 |
2020年 | 146篇 |
2019年 | 161篇 |
2018年 | 167篇 |
2017年 | 157篇 |
2016年 | 115篇 |
2015年 | 125篇 |
2014年 | 209篇 |
2013年 | 760篇 |
2012年 | 177篇 |
2011年 | 231篇 |
2010年 | 181篇 |
2009年 | 297篇 |
2008年 | 357篇 |
2007年 | 388篇 |
2006年 | 343篇 |
2005年 | 348篇 |
2004年 | 298篇 |
2003年 | 290篇 |
2002年 | 280篇 |
2001年 | 216篇 |
2000年 | 209篇 |
1999年 | 191篇 |
1998年 | 185篇 |
1997年 | 171篇 |
1996年 | 117篇 |
1995年 | 72篇 |
1994年 | 54篇 |
1993年 | 60篇 |
1992年 | 46篇 |
1991年 | 21篇 |
1990年 | 17篇 |
1989年 | 24篇 |
1988年 | 22篇 |
1987年 | 12篇 |
1986年 | 15篇 |
1985年 | 27篇 |
1984年 | 19篇 |
1983年 | 9篇 |
1982年 | 14篇 |
1981年 | 13篇 |
1980年 | 11篇 |
1979年 | 6篇 |
1978年 | 9篇 |
1977年 | 6篇 |
1976年 | 5篇 |
1973年 | 2篇 |
排序方式: 共有6860条查询结果,搜索用时 296 毫秒
11.
Miklós Csörgő 《Periodica Mathematica Hungarica》2005,50(1-2):1-27
Summary This article provides a glimpse of some of the highlights of the joint work of Endre Csáki and Pál Révész since 1979. The topics of this short exploration of the rich stochastic milieu of this inspiring collaboration revolve around Brownian motion, random walks and their long excursions, local times and additive functionals, iterated processes, almost sure local and global central limit theorems, integral functionals of geometric stochastic processes, favourite sites--favourite values and jump sizes for random walk and Brownian motion, random walking in a random scenery, and large void zones and occupation times for coalescing random walks. 相似文献
12.
Mrio J. Edmundo 《Mathematical Logic Quarterly》2005,51(6):639-641
We show that if G is a definably compact, definably connected definable group defined in an arbitrary o‐minimal structure, then G is divisible. Furthermore, if G is defined in an o‐minimal expansion of a field, k ∈ ? and pk : G → G is the definable map given by pk (x ) = xk for all x ∈ G , then we have |(pk )–1(x )| ≥ kr for all x ∈ G , where r > 0 is the maximal dimension of abelian definable subgroups of G . (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
13.
In this paper we continue to study the spectral norms and their completions ([4]) in the case of the algebraic closure $ \overline {\mathbb Q} $ of ? in ?. Let $ \widetilde{\overline{\mathbb{Q}}} $ be the completion of $ \overline {\mathbb Q} $ relative to the spectral norm. We prove that $ \widetilde{\overline{\mathbb{Q}}} $ can be identified with the R‐subalgebra of all symmetric functions of C(G), where C(G) denotes the ?‐Banach algebra of all continuous functions defined on the absolute Galois group G = Gal$ {\overline {\mathbb Q}} / {\mathbb Q} $. We prove that any compact, closed to conjugation subset of ? is the pseudo‐orbit of a suitable element of $ \widetilde{\overline{\mathbb{Q}}} $. We also prove that the topological closure of any algebraic number field in $ \widetilde{\overline{\mathbb{Q}}} $ is of the form $\widetilde{\mathbb{Q}[x]}$ with x in $ \widetilde{\overline{\mathbb{Q}}} $. 相似文献
14.
In the present paper we give necessary and sufficient conditions for the subgroup separability of the fundamental group of a finite graph of groups with finitely generated abelian vertex groups.
15.
Hongchao Li Yufeng Hu Yanguang Zhang Dongge Ma Lixiang Wang Xiabin Jing Fosong Wang 《Journal of polymer science. Part A, Polymer chemistry》2004,42(16):3947-3953
A conjugated poly(p‐CN‐phenylenevinylene) (PCNPV) containing both electron‐donating triphenylamine units and electron‐withdrawing cyano groups was prepared via Knoevenagel condensation in a good yield. Gel permeation chromatography suggested that the soluble polymer had a very high weight‐average molecular weight of 309,000. A bright and saturated red emission was observed under UV excitation in solution and film. Cyclic voltammetry showed that the polymer presented quasi‐reversible oxidation with a relatively low potential because of the triphenylamine unit. A single‐layer indium tin oxide/PCNPV/Mg–Ag device emitted a bright red light (633 nm). © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 3947–3953, 2004 相似文献
16.
K. Y. Sandhya C. K. S. Pillai K. Sree Kumar 《Journal of Polymer Science.Polymer Physics》2004,42(7):1289-1298
New hydrogen‐bonded liquid‐crystalline poly(ester amide)s (PEA)s were obtained from 1,4‐terephthaloyl[bis‐(3‐nitro‐N‐anthranilic acid)] (5) or 1,4‐terephthaloyl[bis‐(N‐anthranilic acid)] (6), with or without nitro groups, respectively, through the separate condensation of each with hydroquinone or dihydroxynaphthalene. The dicarboxylic monomers were synthesized from 2‐aminobenzoic acid. The phase behavior of the monomers and polymers were studied with differential scanning calorimetry, polarized light microscopy, and wide‐angle X‐ray diffraction methods. Monomer 5, containing nitro groups, exhibited a smectic liquid‐crystalline phase, whereas the texture of monomer 6 without nitro groups appeared to be nematic. The PEAs containing nitro groups exhibited polymorphism (smectic and nematic), whereas those without nitro groups exhibited only one phase transition (a nematic threaded texture). The changes occurring in the phase behavior of the polymers were explained by the introduction of nitro groups. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 1289–1298, 2004 相似文献
17.
We construct the polynomial quantization on the space G/H where G=SL(n,R),H=GL(n–1,R). It is a variant of quantization in the spirit of Berezin. In our case covariant and contravariant symbols are polynomials on G/H. We introduce a multiplication of covariant symbols, establish the correspondence principle, study transformations of symbols (the Berezin transform) and of operators. We write a full asymptotic decomposition of the Berezin transform. 相似文献
18.
Oksana Yakimova 《Acta Appl Math》2004,81(1):339-345
In this paper, we give a partial classification of commutative spaces of Heisenberg type. Several classification results were known previously. In order to avoid complicated technical details, we restrict ourselves to saturated commutative spaces. Our results are presented in Table II. 相似文献
19.
This work consists of two parts. In Part I, we shall give a systematic study of Lorentz conformal structure from structural viewpoints. We study manifolds with split-complex structure. We apply general results on split-complex structure for the study of Lorentz surfaces.In Part II, we study the conformal realization of Lorentz surfaces in the Minkowski 3-space via conformal minimal immersions. We apply loop group theoretic Weierstrass-type representation of timelike constant mean curvature for timelike minimal surfaces. Classical integral representation formula for timelike minimal surfaces will be recovered from loop group theoretic viewpoint. 相似文献
20.
D. P. Zhelobenko 《Acta Appl Math》2004,81(1):347-354
A special class of associative algebras is introduced and studied. A criteria of semisimplicity for suitable category of modules is obtained. 相似文献