全文获取类型
收费全文 | 13100篇 |
免费 | 1489篇 |
国内免费 | 1687篇 |
专业分类
化学 | 1053篇 |
晶体学 | 52篇 |
力学 | 891篇 |
综合类 | 333篇 |
数学 | 10328篇 |
物理学 | 3619篇 |
出版年
2024年 | 29篇 |
2023年 | 158篇 |
2022年 | 185篇 |
2021年 | 223篇 |
2020年 | 280篇 |
2019年 | 318篇 |
2018年 | 316篇 |
2017年 | 362篇 |
2016年 | 401篇 |
2015年 | 315篇 |
2014年 | 606篇 |
2013年 | 852篇 |
2012年 | 564篇 |
2011年 | 781篇 |
2010年 | 700篇 |
2009年 | 901篇 |
2008年 | 1022篇 |
2007年 | 1034篇 |
2006年 | 846篇 |
2005年 | 819篇 |
2004年 | 632篇 |
2003年 | 738篇 |
2002年 | 605篇 |
2001年 | 484篇 |
2000年 | 559篇 |
1999年 | 472篇 |
1998年 | 439篇 |
1997年 | 377篇 |
1996年 | 271篇 |
1995年 | 159篇 |
1994年 | 152篇 |
1993年 | 105篇 |
1992年 | 75篇 |
1991年 | 65篇 |
1990年 | 51篇 |
1989年 | 39篇 |
1988年 | 40篇 |
1987年 | 26篇 |
1986年 | 21篇 |
1985年 | 43篇 |
1984年 | 41篇 |
1983年 | 15篇 |
1982年 | 32篇 |
1981年 | 15篇 |
1980年 | 20篇 |
1979年 | 20篇 |
1978年 | 13篇 |
1977年 | 13篇 |
1976年 | 8篇 |
1936年 | 6篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
Michael T. Jury David W. Kribs 《Proceedings of the American Mathematical Society》2005,133(1):213-222
Given a row contraction of operators on a Hilbert space and a family of projections on the space that stabilizes the operators, we show there is a unique minimal joint dilation to a row contraction of partial isometries that satisfy natural relations. For a fixed row contraction the set of all dilations forms a partially ordered set with a largest and smallest element. A key technical device in our analysis is a connection with directed graphs. We use a Wold decomposition for partial isometries to describe the models for these dilations, and we discuss how the basic properties of a dilation depend on the row contraction.
32.
In the present paper, some new almost fixed point theorems and fixed point theorems for lower semicontinuous type multivalued mappings are obtained in metrizable H-spaces. 相似文献
33.
34.
《Surface and interface analysis : SIA》2003,35(2):146-150
We report the first application of pump–probe second harmonic generation (SHG) measurements to characterize optically induced magnetization in non‐magnetic multilayer semiconductors. In the experiment, spin‐polarized electrons are excited selectively by a pump beam in the GaAs layer of GaAs/GaSb/InAs structures. However, the resulting net magnetization manifests itself through the induced SHG probe signal from the GaSb/InAs interface, thus indicating a spin‐polarized electron transport across the heterostructure. We find that the magnetization dynamics are governed by an interplay between the spin density evolution at the interfaces and the spin relaxation. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
35.
Andrey Pereverzev 《Foundations of Physics Letters》2003,16(5):411-428
We argue that it may be possible to consistently explain the quantum measurement by assuming that the wave function is in one-to-one correspondence with objective physical reality and has no probabilistic interpretation. In the context of such approach we consider the model of a harmonic oscillator linearly coupled to a heat bath and treat the oscillator as the system being measured. Three classes of initial pure states for the bath are considered. Exact expressions for the average values and variances of the oscillator coordinate and momentum as functions of time are considered for each class of pure states. It is shown that these quantities exhibit different asymptotic behavior for different classes of initial states of the bath. In particular, if each mode of the bath is initially in a coherent state, then for an arbitrary initial state of the oscillator the variances of the oscillator coordinate and momentum asymptotically approach the same values as for a coherent state of the free oscillator, while the averages of coordinate and momentum show a Brownian-like behavior. We argue that such behavior shows several features of the quantum measurement and supports our interpretation of the wave function. 相似文献
36.
SUN Qiyu 《数学年刊B辑(英文版)》2003,24(3):367-386
In this paper, the author at first develops a method to study convergence of the cascade algorithm in a Banach space without stable assumption on the initial (see Theorem 2.1), and then applies the previous result on the convergence to characterizing compactly supported refinable distributions in fractional Sobolev spaces and Holder continuous spaces (see Theorems 3.1, 3.3, and 3.4). Finally the author applies the above characterization to choosing appropriate initial to guarantee the convergence of the cascade algorithm (see Theorem 4.2). 相似文献
37.
Lova Zakariasy 《Proceedings of the American Mathematical Society》2003,131(4):1177-1180
We show that on the harmonic Bergman spaces, the Hankel operators with nonconstant harmonic symbol cannot be of finite rank.
38.
39.
A locally convex space is said to be a Gateaux differentiability space (GDS)provided every continuous convex function defined on a nonempty convex open subset D of the space is densely Gateaux differentiable in D.This paper shows that the product of a GDS and a family of separable Frechet spaces is a GDS,and that the product of a GDS and an arbitrary locally convex space endowed with the weak topology is a GDS. 相似文献
40.
给出了Banach空间的一个增算子不动点定理,将这一定理应用到Banach空间的积分-微分方程,给出了一类积分-微分方程的连续可微最大解和连续可微最小解的存在性定理. 相似文献