全文获取类型
收费全文 | 372146篇 |
免费 | 2904篇 |
国内免费 | 778篇 |
专业分类
化学 | 182736篇 |
晶体学 | 5431篇 |
力学 | 18483篇 |
综合类 | 10篇 |
数学 | 51249篇 |
物理学 | 117919篇 |
出版年
2020年 | 2196篇 |
2019年 | 2296篇 |
2018年 | 11084篇 |
2017年 | 11835篇 |
2016年 | 8435篇 |
2015年 | 3710篇 |
2014年 | 4613篇 |
2013年 | 11882篇 |
2012年 | 13109篇 |
2011年 | 22747篇 |
2010年 | 14521篇 |
2009年 | 14589篇 |
2008年 | 20309篇 |
2007年 | 23474篇 |
2006年 | 10271篇 |
2005年 | 15509篇 |
2004年 | 11437篇 |
2003年 | 10588篇 |
2002年 | 8651篇 |
2001年 | 9359篇 |
2000年 | 7123篇 |
1999年 | 5327篇 |
1998年 | 4146篇 |
1997年 | 4166篇 |
1996年 | 3970篇 |
1995年 | 3698篇 |
1994年 | 3634篇 |
1993年 | 3320篇 |
1992年 | 4008篇 |
1991年 | 4227篇 |
1990年 | 3906篇 |
1989年 | 3859篇 |
1988年 | 3789篇 |
1987年 | 3705篇 |
1986年 | 3464篇 |
1985年 | 4437篇 |
1984年 | 4557篇 |
1983年 | 3702篇 |
1982年 | 3847篇 |
1981年 | 3645篇 |
1980年 | 3562篇 |
1979年 | 3962篇 |
1978年 | 4208篇 |
1977年 | 3938篇 |
1976年 | 3966篇 |
1975年 | 3731篇 |
1974年 | 3798篇 |
1973年 | 3822篇 |
1972年 | 2520篇 |
1971年 | 2115篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
951.
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
952.
In this paper, we consider questions related to the structure of inverse matrices of linear bounded operators acting in infinite-dimensional complex Banach spaces. We obtain specific estimates of elements of inverse matrices for bounded operators whose matrices have a special structure. Matrices are introduced as special operator-valued functions on an index set. The matrix structure is described by the behavior of the given function on elements of a special partition of the index set. The method used for deriving the estimates is based on an analysis of Fourier series of strongly continuous periodic functions. 相似文献
953.
954.
This work deals with the polymer latexes synthesized using zinc-containing monomers. The effect of the ligand environment of the zinc-containing monomers on the colloidal and rheological properties of the latexes, as well as on mechanical properties of their films is studied. Mixed zinc salts containing the residues of saturated and unsaturated carboxylic acids are shown to be more efficient cross-linking agents than the symmetric salts of this metal. 相似文献
955.
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
956.
We demonstrate that a pair of additive quintic equations in at least 34 variables has a nontrivial integral solution, subject only to an 11-adic solubility hypothesis. This is achieved by an application of the Hardy–Littlewood method, for which we require a sharp estimate for a 33.998th moment of quintic exponential sums. We are able to employ p-adic iteration in a form that allows the estimation of such a mean value over a complete unit square, thereby providing an approach that is technically simpler than those of previous workers and flexible enough to be applied to related problems. 相似文献
957.
This paper proposes a model for the parametric representation of linguistic hedges in Zadeh’s fuzzy logic. In this model each linguistic truth-value, which is generated from a primary term of the linguistic truth variable, is identified by a real number r depending on the primary term. It is shown that the model yields a method of efficiently computing linguistic truth expressions accompanied with a rich algebraic structure of the linguistic truth domain, namely De Morgan algebra. Also, a fuzzy logic based on the parametric representation of linguistic truth-values is introduced. 相似文献
958.
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
959.
960.
Effects of various cardioactive agents and a water extract of the pilose antler of Cervus nippon var. mantchuricus on periodic beating of cultured myocardial cell sheets were examined by using an image analyzing system. Norepinephrine increased the beating rate and the beating amplitude, whereas digoxin and forskolin enlarged only the beating amplitude. Verapamil and propranolol decreased both the beating rate and the beating amplitude. The water extract of the pilose antler showed no remarkable effects in a standard medium (2.1 mM Ca2+). However, it significantly increased the beating amplitude when the beating was suppressed by replacement with a low calcium medium (0.5 mM Ca2+). A similar effect was found for 70% ethanol-soluble and -insoluble fractions of the extract. 相似文献