全文获取类型
收费全文 | 356123篇 |
免费 | 2761篇 |
国内免费 | 613篇 |
专业分类
化学 | 173622篇 |
晶体学 | 5922篇 |
力学 | 17385篇 |
综合类 | 12篇 |
数学 | 49576篇 |
物理学 | 112980篇 |
出版年
2021年 | 2176篇 |
2020年 | 2559篇 |
2019年 | 2845篇 |
2018年 | 11337篇 |
2017年 | 12134篇 |
2016年 | 8939篇 |
2015年 | 3805篇 |
2014年 | 5167篇 |
2013年 | 12074篇 |
2012年 | 12901篇 |
2011年 | 22080篇 |
2010年 | 14246篇 |
2009年 | 14353篇 |
2008年 | 19209篇 |
2007年 | 22317篇 |
2006年 | 9237篇 |
2005年 | 14077篇 |
2004年 | 10461篇 |
2003年 | 9990篇 |
2002年 | 8015篇 |
2001年 | 8211篇 |
2000年 | 6322篇 |
1999年 | 4634篇 |
1998年 | 3760篇 |
1997年 | 3636篇 |
1996年 | 3525篇 |
1995年 | 3241篇 |
1994年 | 3137篇 |
1993年 | 2972篇 |
1992年 | 3652篇 |
1991年 | 3587篇 |
1990年 | 3505篇 |
1989年 | 3547篇 |
1988年 | 3503篇 |
1987年 | 3450篇 |
1986年 | 3286篇 |
1985年 | 4142篇 |
1984年 | 4246篇 |
1983年 | 3412篇 |
1982年 | 3522篇 |
1981年 | 3503篇 |
1980年 | 3236篇 |
1979年 | 3627篇 |
1978年 | 3707篇 |
1977年 | 3771篇 |
1976年 | 3547篇 |
1975年 | 3249篇 |
1974年 | 3239篇 |
1973年 | 3212篇 |
1972年 | 2228篇 |
排序方式: 共有10000条查询结果,搜索用时 171 毫秒
981.
982.
983.
984.
S. V. Valueva L. N. Borovikova V. V. Koreneva Ya. I. Nazarkina A. I. Kipper V. V. Kopeikin 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2007,81(7):1170-1173
Nanostructures formed during the reduction of ionic selenium in the selenite-ascorbate redox system in an aqueous solution of bovine serum albumin (BSA) were studied using static and dynamic light scattering and flow birefringence. It was established that this process results in the formation of stable aggregates of selenium nanoparticles that adsorb BSA molecules. It was found that highly-ordered superhigh-molecular-weight spherical nanostructures with high density and unique morphology are formed. Experiments with a cell culture of promyelocytic leukemia HL-60 showed that BSA adsorbed on selenium nanoparticles can inhibit the growth of tumor cells and deactivate free radicals with an efficiency comparable with that of sodium selenite. 相似文献
985.
K. V. Storozhuk 《Proceedings of the American Mathematical Society》2007,135(6):1861-1863
We give a short proof of a generalization of the Rolewicz theorem based on the uniform boundedness principle.
986.
J. MALINEN O. NEVANLINNA V. TURUNEN Z. YUAN 《数学学报(英文版)》2007,23(4):745-748
Let T be a bounded linear operator in a Banach space, with σ(T)={1}. In 1983, Esterle-Berkani' s conjecture was proposed for the decay of differences (I - T) T^n as follows: Eitheror lim inf (n→∞(n+1)||(I-T)T^n||≥1/e or T = I. We prove this claim and discuss some of its consequences. 相似文献
987.
Template synthesis of a nickel(II) chelate with an (N'N'S'S)-donor ligand, 4'6-dimethyl-2'8-di-thio-3'7-diaza-5-oxanonanedithioamide-1'9, with a metal ion:ligand ratio of 1:1 is realized in getalin-immobilized nickel(II) hexacyanoferrate(II) matrices contacting with aqueous solutions containing dithiox-amide, acetaldehyde (pH > 10), where the latter two compounds play the role of ligand synthons. On directcontact of dithioxamide and acetaldehyde in the solution in the absence of Ni(II), the above (N,N,S,S)-donorligand does not form, and no nickel(II) chelates with this ligand can be obtained by reactions of known nickel(II) dithiooxamide complexes with acetaldehyde. 相似文献
988.
989.
The Laplacian and Dirac operators on critical planar graphs 总被引:6,自引:0,他引:6
R. Kenyon 《Inventiones Mathematicae》2002,150(2):409-439
On a periodic planar graph whose edge weights satisfy a certain simple geometric condition, the discrete Laplacian and Dirac
operators have the property that their determinants and inverses only depend on the local geometry of the graph. We obtain
explicit expressions for the logarithms of the (normalized) determinants, as well as the inverses of these operators. We relate
the logarithm of the determinants to the volume plus mean curvature of an associated hyperbolic ideal polyhedron. In the associated
dimer and spanning tree models, for which the determinants of the Dirac operator and the Laplacian respectively play the role
of the partition function, this allows us to compute the entropy and correlations in terms of the local geometry. In addition,
we define a continuous family of special discrete holomorphic functions which, via convolutions, gives a general process for
constructing discrete holomorphic functions and discrete harmonic functions on critical planar graphs.
Oblatum 6-III-2002 & 12-VI-2002?Published online: 6 August 2002 相似文献
990.
Recently, the theory of sortability of partition property has been shown to be an effective tool to prove the existence of an optimal partition with that property. In this paper, we extend the theory to multi-partition where the partition is on t types of components. We apply our results to settle an optimal assignment problem whose proof was incomplete as given in the literature. 相似文献