全文获取类型
收费全文 | 658篇 |
免费 | 17篇 |
国内免费 | 22篇 |
专业分类
化学 | 280篇 |
晶体学 | 4篇 |
力学 | 2篇 |
数学 | 323篇 |
物理学 | 88篇 |
出版年
2024年 | 1篇 |
2023年 | 2篇 |
2022年 | 3篇 |
2021年 | 9篇 |
2020年 | 4篇 |
2019年 | 9篇 |
2018年 | 10篇 |
2017年 | 13篇 |
2016年 | 8篇 |
2015年 | 5篇 |
2014年 | 9篇 |
2013年 | 27篇 |
2012年 | 26篇 |
2011年 | 46篇 |
2010年 | 29篇 |
2009年 | 50篇 |
2008年 | 62篇 |
2007年 | 48篇 |
2006年 | 36篇 |
2005年 | 24篇 |
2004年 | 28篇 |
2003年 | 25篇 |
2002年 | 12篇 |
2001年 | 14篇 |
2000年 | 19篇 |
1999年 | 17篇 |
1998年 | 21篇 |
1997年 | 18篇 |
1996年 | 16篇 |
1995年 | 17篇 |
1994年 | 18篇 |
1993年 | 12篇 |
1992年 | 8篇 |
1991年 | 5篇 |
1990年 | 7篇 |
1989年 | 2篇 |
1988年 | 4篇 |
1987年 | 2篇 |
1986年 | 5篇 |
1985年 | 1篇 |
1984年 | 3篇 |
1983年 | 2篇 |
1982年 | 3篇 |
1981年 | 4篇 |
1980年 | 1篇 |
1979年 | 5篇 |
1978年 | 3篇 |
1977年 | 1篇 |
1976年 | 3篇 |
排序方式: 共有697条查询结果,搜索用时 31 毫秒
71.
In this article, we investigate some conditions for a real cyclic extension K over Q to satisfy the property that every totally positive unit of K is a square. As an application, we give a partial answer to Taussky's conjecture. We then extend our result to real abelian extensions of certain type. 相似文献
72.
Benjamin McKay 《Differential Geometry and its Applications》2007,25(3):277-280
A map between manifolds which matches up families of complete vector fields is a fiber bundle mapping on each orbit of those vector fields. 相似文献
73.
Albert Compta 《Linear algebra and its applications》2007,421(1):45-52
Given an observable pair of matrices (C, A) we consider the manifold of (C, A)-invariant subspaces having a fixed Brunovsky-Kronecker structure. Using Arnold techniques we obtain the explicit form of a miniversal deformation of a marked (C, A)-invariant subspace with respect to the usual equivalence relation. As an application, we obtain the dimension of the orbit and we characterize the structurally stable subspaces (those with open orbit). 相似文献
74.
The quantitative relationships between 29Si chemical shifts and (a) the SiOT (T = Al or Si) angles and (b) the nature of the cations of the alkali forms of zeolites can be account for by the changes of charge density and p electron population of the Si atoms as calculated by the extended Hückel method on cluster models. 相似文献
75.
V. Braungardt 《Topology》2005,44(3):641-659
We prove that for every natural number k there are simply connected topological four-manifolds which have at least k distinct smooth structures supporting Einstein metrics, and also have infinitely many distinct smooth structures not supporting Einstein metrics. Moreover, all these smooth structures become diffeomorphic to each other after connected sum with only one copy of the complex projective plane. We prove that manifolds with these properties cover a large geographical area. 相似文献
76.
采用液相外延方法,生长出外延层与衬底之间的失配度△α/α≤1.6×10-3界面平直、组分恒定的InAsPSb/InAs外延晶体.单异质结外延层,得到了3.09μm波长的激光输出,双异质结外延片也得到了较好的伏-安特性曲线. 相似文献
77.
78.
Tadeusz ANTCZAK 《数学物理学报(B辑英文版)》2017,37(4):1133-1150
In this paper, both Fritz John and Karush-Kuhn-Tucker necessary optimality conditions are established for a (weakly) LU-efficient solution in the considered nonsmooth multiobjective programming problem with the multiple interval-objective function. Further, the sufficient optimality conditions for a (weakly) LU-efficient solution and several duality results in Mond-Weir sense are proved under assumptions that the functions constituting the considered nondifferentiable multiobjective programming problem with the multiple interval-objective function are convex. 相似文献
79.
Polgári Z Ajtony Z Kregsamer P Streli C Mihucz VG Réti A Budai B Kralovánszky J Szoboszlai N Záray G 《Talanta》2011,85(4):1959-1965
Microanalytical methods suitable for the determination of Fe, Cu in HT-29 (human colon adenocarcinoma) cells treated with different iron compounds (Fe(II) sulfate, Fe(III) chloride, Fe(III) citrate and Fe(III) transferrin) and cultured in medium supplemented or not with 10% (v/v) fetal calf serum (FCS) by total reflection X-ray fluorescence spectrometry (TXRF) and simultaneous graphite furnace atomic absorption spectrometry (GF-AAS) were developed. The developed TXRF method was also suitable for Zn determination in the samples. The main advantage of the proposed methods is the execution of all sample preparation steps following incubation and prior to the elemental analysis in the same Eppendorf tubes. Sample preparation was performed at microscale (115 μL sample volume) with 65% nitric acid and 30% hydrogen peroxide. According to scanning electron microscopic measurements, the organic matrix of the cell samples could be eliminated to the extent that accurate results were obtained for Cu and Fe by analyzing the same samples by TXRF and GF-AAS. Concerning the iron uptake, HT-29 cells incubated in FCS-free medium contained Fe in cca. 5-50 times higher amounts compared to cells cultured in FCS supplemented medium. Pronounced differences in the iron uptake compared to the iron supply (inorganic vs. organic chelated as well as iron(II) vs. iron(III)) were observed in the case of cell lines incubated in FCS-free medium. 相似文献
80.
The spectral properties of periodic Jacobi matrices in Minkowski spaces are studied. An inverse problem for these matrices is investigated, and necessary and sufficient conditions under which the problem is solvable are presented. Uniqueness results are also discussed, and an algorithm to construct the solutions and illustrative examples is provided. 相似文献