全文获取类型
收费全文 | 1056篇 |
免费 | 63篇 |
国内免费 | 7篇 |
专业分类
化学 | 747篇 |
晶体学 | 1篇 |
力学 | 13篇 |
数学 | 202篇 |
物理学 | 163篇 |
出版年
2023年 | 6篇 |
2022年 | 8篇 |
2021年 | 19篇 |
2020年 | 34篇 |
2019年 | 39篇 |
2018年 | 24篇 |
2017年 | 19篇 |
2016年 | 43篇 |
2015年 | 40篇 |
2014年 | 46篇 |
2013年 | 74篇 |
2012年 | 56篇 |
2011年 | 74篇 |
2010年 | 60篇 |
2009年 | 28篇 |
2008年 | 89篇 |
2007年 | 53篇 |
2006年 | 57篇 |
2005年 | 42篇 |
2004年 | 29篇 |
2003年 | 24篇 |
2002年 | 25篇 |
2001年 | 15篇 |
2000年 | 15篇 |
1999年 | 18篇 |
1998年 | 6篇 |
1997年 | 13篇 |
1996年 | 7篇 |
1995年 | 9篇 |
1994年 | 14篇 |
1993年 | 8篇 |
1992年 | 7篇 |
1991年 | 5篇 |
1989年 | 6篇 |
1988年 | 8篇 |
1987年 | 5篇 |
1985年 | 5篇 |
1983年 | 5篇 |
1981年 | 10篇 |
1980年 | 7篇 |
1979年 | 6篇 |
1978年 | 4篇 |
1977年 | 5篇 |
1976年 | 5篇 |
1975年 | 9篇 |
1974年 | 7篇 |
1973年 | 3篇 |
1972年 | 4篇 |
1967年 | 3篇 |
1933年 | 3篇 |
排序方式: 共有1126条查询结果,搜索用时 31 毫秒
1.
Hendrik Van Maldeghem 《Journal of Geometry》1997,58(1-2):192-202
We characterize in a geometrical way those Suzuki-Tits ovoids which are defined over a perfect fieidK (or equivalently living inside a self polar symplectic quadrangle). We simplify our axioms in the particular cases that (1) the associated Suzuki group has exactly two orbits in the set of lines ofPG(3,K), and (2) the ovoid is finite.Senior Research Associate at the Belgian National Fund for Scientific Research 相似文献
2.
3.
4.
Using the result by D. Gessler, we show that any invariant variational bivector (resp., variational 2-form) on an evolution equation with nondegenerate right-hand side is Hamiltonian (resp., symplectic). 相似文献
5.
6.
7.
8.
Hendrik Grundling 《Communications in Mathematical Physics》1988,114(1):69-91
Since there are some important systems which have constraints not contained in their field algebras, we develop here in aC*-context the algebraic structures of these. The constraints are defined as a groupG acting as outer automorphisms on the field algebra , :G Aut ,
G
Inn , and we find that the selection ofG-invariant states on is the same as the selection of states onM(G
) by (U
g)=1gG, whereU
g M (G
)/ are the canonical elements implementing
g
. These states are taken as the physical states, and this specifies the resulting algebraic structure of the physics inM(G
), and in particular the maximal constraint free physical algebra . A nontriviality condition is given for to exist, and we extend the notion of a crossed product to deal with a situation whereG is not locally compact. This is necessary to deal with the field theoretical aspect of the constraints. Next theC*-algebra of the CCR is employed to define the abstract algebraic structure of Gupta-Bleuler electromagnetism in the present framework. The indefinite inner product representation structure is obtained, and this puts Gupta-Bleuler electromagnetism on a rigorous footing. Finally, as a bonus, we find that the algebraic structures just set up, provide a blueprint for constructive quadratic algebraic field theory. 相似文献
9.
Thomas P J Linsinger Alexander Bernreuther Philippe Corbisier Marta Dabrio Håkan Emteborg Andrea Held Andrée Lamberty Gaida Lapitajs Marina Ricci Gert Roebben Stefanie Trapmann Franz Ulberth Hendrik Emons 《Accreditation and quality assurance》2007,12(3-4):167-174
The potential approaches for third-party assessment of reference material producers are revisited and the activities of the
Reference Materials (RM) Unit of the Institute for Reference Materials and Measurements (IRMM) to obtain accreditation to
ISO Guide 34 and ISO 17025 are described. Accreditation was related to the Unit as all matrix RM activities of the institute
are concentrated there. A management system was established that allows sufficient flexibility to be applicable to a wide
range of RMs while being precise enough to ensure compliance with ISO Guides 30, 31 and especially 34 and 35. Accreditation
was achieved in 2004 with independent scopes for testing and RM production and was confirmed and extended in 2005. The key
aspects of the RM Unit's management system for RM production are presented.
Presented at BERM-10, April 2006, Charleston, SC, USA 相似文献
10.
Udo Feldkamp Ron Wacker Hendrik Schroeder Wolfgang Banzhaf Christof M Niemeyer 《Chemphyschem》2004,5(3):367-372
We report on the microarray-based in vitro evaluation of two libraries of DNA oligonucleotide sequences, designed in silico for applications in supramolecular self-assembly, such as DNA computing and DNA-based nanosciences. In this first study which is devoted to the comparison of sequence motif properties theoretically predicted with their performance in real-life, the DNA-directed immobilization (DDI) of proteins was used as an example of DNA-based self-assembly. Since DDI technologies, DNA computing, and DNA nanoconstruction essentially depend on similar prereguisites, in particular, large and uniform hybridization efficiencies combined with low nonspecific cross-reactivity between individual sequences, we anticipate that the microarray approach demonstrated here will enable rapid evaluation of other DNA sequence libraries. 相似文献