全文获取类型
收费全文 | 66194篇 |
免费 | 2349篇 |
国内免费 | 152篇 |
专业分类
化学 | 40362篇 |
晶体学 | 380篇 |
力学 | 1303篇 |
综合类 | 1篇 |
数学 | 12836篇 |
物理学 | 13813篇 |
出版年
2023年 | 485篇 |
2022年 | 405篇 |
2021年 | 807篇 |
2020年 | 1087篇 |
2019年 | 1032篇 |
2018年 | 1285篇 |
2017年 | 1168篇 |
2016年 | 2393篇 |
2015年 | 2000篇 |
2014年 | 2090篇 |
2013年 | 4221篇 |
2012年 | 4167篇 |
2011年 | 4244篇 |
2010年 | 2592篇 |
2009年 | 2216篇 |
2008年 | 3462篇 |
2007年 | 3220篇 |
2006年 | 2918篇 |
2005年 | 2824篇 |
2004年 | 2479篇 |
2003年 | 1984篇 |
2002年 | 1814篇 |
2001年 | 1197篇 |
2000年 | 1179篇 |
1999年 | 888篇 |
1998年 | 696篇 |
1997年 | 602篇 |
1996年 | 769篇 |
1995年 | 572篇 |
1994年 | 644篇 |
1993年 | 616篇 |
1992年 | 611篇 |
1991年 | 530篇 |
1990年 | 565篇 |
1989年 | 470篇 |
1988年 | 499篇 |
1987年 | 430篇 |
1986年 | 428篇 |
1985年 | 600篇 |
1984年 | 584篇 |
1983年 | 428篇 |
1982年 | 498篇 |
1981年 | 519篇 |
1980年 | 418篇 |
1979年 | 418篇 |
1978年 | 440篇 |
1977年 | 398篇 |
1976年 | 416篇 |
1975年 | 380篇 |
1974年 | 379篇 |
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
61.
The capability of gated saturable absorbers for single-pulse selection is studied theoretically using the classical space-time-dependent rate-equation model. The dynamics of operation is followed experimentally by the well-known pump—probe technique. Comparing the theoretical and experimental results, it is found that gated saturable absorbers can efficiently be used for pulse forming and pulse selection of pulses longer than picosecond. 相似文献
62.
63.
64.
65.
66.
67.
Aidan Mooney John G. Keating Daniel M. Heffernan 《Chaos, solitons, and fractals》2006,30(5):1088-1097
A digital watermark is a visible, or preferably invisible, identification code that is permanently embedded in digital media, to prove owner authentication and provide protection for documents. Given the interest in watermark generation using chaotic functions a detailed study of one chaotic function for this purpose is performed. In this paper, we present an approach for the generation of watermarks using the logistic map. Using this function, in conjunction with seed management, it is possible to generate chaotic sequences that may be used to create highpass or lowpass digital watermarks. In this paper we provide a detailed study on the generation of optically detectable watermarks and we provide some guidelines on successful chaotic watermark generation using the logistic map, and show using a recently published scheme, how care must be taken in the selection of the function seed. 相似文献
68.
This paper attempts to develop a theory of sufficiency in the setting of non-commutative algebras parallel to the ideas in
classical mathematical statistics. Sufficiency of a coarse-graining means that all information is extracted about the mutual
relation of a given family of states. In the paper sufficient coarse-grainings are characterized in several equivalent ways
and the non-commutative analogue of the factorization theorem is obtained. As an application we discuss exponential families.
Our factorization theorem also implies two further important results, previously known only in finite Hilbert space dimension,
but proved here in generality: the Koashi-Imoto theorem on maps leaving a family of states invariant, and the characterization
of the general form of states in the equality case of strong subadditivity.
Supported by the EU Research Training Network Quantum Probability with Applications to Physics, Information Theory and Biology
and Center of Excellence SAS Physics of Information I/2/2005.
Supported by the Hungarian grant OTKA T032662 相似文献
69.
We present a new approach to study the convergence of Newton's method in Banach spaces, which relax the conditions appearing in the usual studies. The approach is based on the bound required for the second derivative of the operator involved. An application to a nonlinear integral equation is presented. 相似文献
70.
Balázs Szendröi 《Mathematische Zeitschrift》2002,240(2):233-241
This note shows that a certain toric quotient of the quintic Calabi-Yau threefold in provides a counterexample to a recent conjecture of Cox and Katz concerning nef cones of toric hypersurfaces.
Received: 8 February 2001; in final form: 17 September 2001 / Published online: 1 February 2002 相似文献