全文获取类型
收费全文 | 52072篇 |
免费 | 1742篇 |
国内免费 | 110篇 |
专业分类
化学 | 30495篇 |
晶体学 | 241篇 |
力学 | 1099篇 |
综合类 | 2篇 |
数学 | 9161篇 |
物理学 | 12926篇 |
出版年
2022年 | 355篇 |
2021年 | 635篇 |
2020年 | 780篇 |
2019年 | 583篇 |
2018年 | 1061篇 |
2017年 | 842篇 |
2016年 | 1434篇 |
2015年 | 1177篇 |
2014年 | 1327篇 |
2013年 | 2816篇 |
2012年 | 2433篇 |
2011年 | 2852篇 |
2010年 | 1571篇 |
2009年 | 1394篇 |
2008年 | 2661篇 |
2007年 | 2629篇 |
2006年 | 2345篇 |
2005年 | 2109篇 |
2004年 | 1645篇 |
2003年 | 1456篇 |
2002年 | 1330篇 |
2001年 | 1004篇 |
2000年 | 965篇 |
1999年 | 645篇 |
1998年 | 554篇 |
1997年 | 552篇 |
1996年 | 685篇 |
1995年 | 574篇 |
1994年 | 607篇 |
1993年 | 675篇 |
1992年 | 554篇 |
1991年 | 444篇 |
1990年 | 482篇 |
1989年 | 404篇 |
1988年 | 410篇 |
1987年 | 401篇 |
1986年 | 366篇 |
1985年 | 558篇 |
1984年 | 570篇 |
1983年 | 504篇 |
1982年 | 518篇 |
1981年 | 525篇 |
1980年 | 461篇 |
1979年 | 409篇 |
1978年 | 466篇 |
1977年 | 435篇 |
1976年 | 391篇 |
1975年 | 365篇 |
1974年 | 328篇 |
1973年 | 342篇 |
排序方式: 共有10000条查询结果,搜索用时 390 毫秒
71.
Paramagnetic pyrroline and 1,2,3,6-tetrahydropyridine derivatives of BODIPY and their diamagnetic analogs have been synthesized and characterized as novel redox double sensor and cation sensitive reagents. 相似文献
72.
I. P. Kuranova K. M. Polyakov E. A. Smirnova W. E. Höhne V. S. Lamzin R. Meijer 《Crystallography Reports》2003,48(6):953-958
Crystals of Saccharomyces cerevisiae inorganic pyrophosphatase suitable for X-ray diffraction study were grown by cocrystallization of the enzyme with cobalt chloride and imidodiphosphate. Saccharomyces cerevisiae is a metal-dependent enzyme which catalyzes hydrolysis of inorganic pyrophosphate to orthophosphate. The three-dimensional structure of this enzyme was solved by the molecular-replacement method and refined at 1.8 Å resolution to an R factor of 19.5%. Cobalt and phosphate ions were revealed in the active centers of both identical subunits (A and B) of the pyrophosphatase molecule. In subunit B, a water molecule was found between two cobalt ions. It is believed that this water molecule acts as an attacking nucleophile in the enzymatic cleavage of the pyrophosphate bond. It was demonstrated that cobalt ions and a phosphate group occupy only part of the potential binding sites (two chemically identical and crystallographically independent subunits have different binding sites). The arrangement of ligands and the structure of the nucleophile-binding site are discussed in relation to the mechanism of action of the enzyme and the nature of the metal activator. 相似文献
73.
We characterise the abelianisation of a group that has a presentation for which the set of relations is invariant under the full symmetric group acting on the set of generators. This improves a result of Emerson.
74.
It is a well-known feature of odd space-time dimensions d that there exist two inequivalent fundamental representations A and B of the Dirac gamma matrices. Moreover, the parity transformation swaps the fermion fields living in A and B. As a consequence, a parity-invariant Lagrangian can only be constructed by incorporating both the representations. Based upon these ideas and contrary to long-held belief, we show that in addition to a discrete exchange symmetry for the massless case, we can also define chiral symmetry provided the Lagrangian contains fields corresponding to both the inequivalent representations. We also study the transformation properties of the corresponding chiral currents under parity and charge-conjugation operations. We work explicitly in 2 + 1 dimensions and later show how some of these ideas generalize to an arbitrary number of odd dimensions. 相似文献
75.
76.
The function lattice, or generalized Boolean algebra, is the set of ℓ-tuples with the ith coordinate an integer between 0 and a bound ni. Two ℓ-tuples t-intersect if they have at least t common nonzero coordinates. We prove a Hilton–Milner type theorem for systems of t-intersecting ℓ-tuples.Received September 29, 2004 相似文献
77.
78.
79.
L. Bugliaro J. Fröhlich G.M. Graf J. Stubbe C. Fefferman 《Communications in Mathematical Physics》1997,187(3):567-582
A Lieb-Thirring-Sobolev type inequality for Pauli Hamiltonians with magnetic fields is derived. The bound is in terms of an
effective field, whose energy is comparable to that of the magnetic field itself. An application to the stability of matter
in magnetic fields is given.
Received: 19 September 1996 / Accepted: 3 January 1997 相似文献
80.
Periodica Mathematica Hungarica - 相似文献