全文获取类型
收费全文 | 22468篇 |
免费 | 760篇 |
国内免费 | 496篇 |
专业分类
化学 | 3076篇 |
晶体学 | 65篇 |
力学 | 331篇 |
综合类 | 132篇 |
数学 | 18503篇 |
物理学 | 1617篇 |
出版年
2023年 | 62篇 |
2022年 | 262篇 |
2021年 | 215篇 |
2020年 | 184篇 |
2019年 | 545篇 |
2018年 | 650篇 |
2017年 | 316篇 |
2016年 | 320篇 |
2015年 | 359篇 |
2014年 | 665篇 |
2013年 | 1442篇 |
2012年 | 780篇 |
2011年 | 1448篇 |
2010年 | 1250篇 |
2009年 | 1542篇 |
2008年 | 1731篇 |
2007年 | 1713篇 |
2006年 | 1286篇 |
2005年 | 880篇 |
2004年 | 783篇 |
2003年 | 630篇 |
2002年 | 445篇 |
2001年 | 372篇 |
2000年 | 398篇 |
1999年 | 530篇 |
1998年 | 424篇 |
1997年 | 366篇 |
1996年 | 413篇 |
1995年 | 410篇 |
1994年 | 380篇 |
1993年 | 343篇 |
1992年 | 302篇 |
1991年 | 210篇 |
1990年 | 181篇 |
1989年 | 197篇 |
1988年 | 138篇 |
1987年 | 150篇 |
1986年 | 132篇 |
1985年 | 189篇 |
1984年 | 181篇 |
1983年 | 102篇 |
1982年 | 170篇 |
1981年 | 150篇 |
1980年 | 103篇 |
1979年 | 83篇 |
1978年 | 106篇 |
1977年 | 73篇 |
1976年 | 55篇 |
1975年 | 18篇 |
1974年 | 14篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
Walter Benz 《Monatshefte für Mathematik》2004,141(1):1-10
The lines of euclidean and hyperbolic geometries are characterized as metric lines in the sense of Blumenthal–Menger, and the lines of spherical and elliptic geometry as periodic ones. In euclidean geometries there do not exist periodic lines. 相似文献
62.
We will prove a result concerning the inclusion of non-trivial invariant ideals inside non-trivial ideals of a twisted crossed
product. We will also give results concerning the primeness and simplicity of crossed products of twisted actions of locally
compact groups on -algebras.
Received: 25 January 2002; in final form: 22 May 2002/Published online: 2 December 2002
This work is partially supported by Hong Kong RGC Direct Grant. 相似文献
63.
In this paper, we consider Girsanov transforms of pure jump type for discontinuous Markov processes. We show that, under some quite natural conditions, the Green functions of the Girsanov transformed process are comparable to those of the original process. As an application of the general results, the drift transform of symmetric stable processes is studied in detail. In particular, we show that the relativistic α-stable process in a bounded C1,1-smooth open set D can be obtained from symmetric α-stable process in D through a combination of a pure jump Girsanov transform and a Feynman-Kac transform. From this, we deduce that the Green functions for these two processes in D are comparable. 相似文献
64.
Murad Özaydin 《Journal of Functional Analysis》2004,215(1):241-252
We classify all functions on a locally compact, abelian group giving equality in an entropy inequality generalizing the Heisenberg Uncertainty Principle. In particular, for functions on a real line, we proof a conjecture of Hirschman published in 1957. 相似文献
65.
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
66.
S. Pumplün 《manuscripta mathematica》1998,97(1):93-108
For a Brauer–Severi variety X over a field k of characteristic not two, every symmetric bilinear space over X up to Witt equivalence is defined over k.
Received: 2 February 1998 相似文献
67.
We shall give a direct proof of the independence result of a Buchholz style-Hydra Game on labeled finite trees. We shall
show that Takeuti-Arai's cut-elimination procedure of and of the iterated inductive definition systems can be directly expressed by the reduction rules of Buchholz's Hydra Game.
As a direct corollary the independence result of the Hydra Game follows.
Received: August 23, 1994 / Revised: July 24, 1995 and May 9, 1996 相似文献
68.
We investigate several versions of a cardinal characteristic defined by Frankiewicz. Vojtáš showed , and Blass showed . We show that all the versions coincide and that is greater than or equal to the splitting number. We prove the consistency of and of .
Received: 2 October 1996 / Revised version: 22 May 1997 相似文献
69.
白三叶草花蜜腺突起环状,位于花丝基部并延续至花托上,属于环状花托/雄蕊蜜腺,蜜腺由分泌表皮和产蜜组织组成.在花的发育过程中,蜜腺由本身的原始细胞分裂,分化而来.分泌表皮具角质层,其上分布有变态气孔器,蜜汁经产蜜组织合成后,经变态气孔器泌出. 相似文献
70.
Summary. We study a diffusion model of an interacting particles system with general drift and diffusion coefficients, and electrostatic
inter-particles repulsion. More precisely, the finite particle system is shown to be well defined thanks to recent results
on multivalued stochastic differential equations (see [2]), and then we consider the behaviour of this system when the number
of particles goes to infinity (through the empirical measure process). In the particular case of affine drift and constant diffusion coefficient,
we prove that a limiting measure-valued process exists and is the unique solution of a deterministic PDE. Our treatment of
the convergence problem (as ) is partly similar to that of T. Chan [3] and L.C.G. Rogers - Z. Shi [5], except we consider here a more general case allowing
collisions between particles, which leads to a second-order limiting PDE.
Received: 5 August 1996 / In revised form: 17 October 1996 相似文献