全文获取类型
收费全文 | 12394篇 |
免费 | 3357篇 |
国内免费 | 1361篇 |
专业分类
化学 | 4179篇 |
晶体学 | 71篇 |
力学 | 228篇 |
综合类 | 107篇 |
数学 | 1334篇 |
物理学 | 11193篇 |
出版年
2024年 | 60篇 |
2023年 | 207篇 |
2022年 | 619篇 |
2021年 | 568篇 |
2020年 | 521篇 |
2019年 | 462篇 |
2018年 | 410篇 |
2017年 | 418篇 |
2016年 | 588篇 |
2015年 | 525篇 |
2014年 | 747篇 |
2013年 | 1015篇 |
2012年 | 782篇 |
2011年 | 905篇 |
2010年 | 733篇 |
2009年 | 745篇 |
2008年 | 943篇 |
2007年 | 916篇 |
2006年 | 866篇 |
2005年 | 751篇 |
2004年 | 659篇 |
2003年 | 573篇 |
2002年 | 555篇 |
2001年 | 409篇 |
2000年 | 436篇 |
1999年 | 299篇 |
1998年 | 324篇 |
1997年 | 229篇 |
1996年 | 131篇 |
1995年 | 117篇 |
1994年 | 87篇 |
1993年 | 78篇 |
1992年 | 77篇 |
1991年 | 48篇 |
1990年 | 58篇 |
1989年 | 52篇 |
1988年 | 27篇 |
1987年 | 25篇 |
1986年 | 29篇 |
1985年 | 26篇 |
1984年 | 22篇 |
1983年 | 8篇 |
1982年 | 12篇 |
1981年 | 9篇 |
1980年 | 5篇 |
1978年 | 11篇 |
1976年 | 5篇 |
1975年 | 3篇 |
1974年 | 3篇 |
1972年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
11.
We propose a unified method for deducing recursive relations for the canonical partition function of a system of noninteracting particles with charge conservation if the particles follow the Bose–Einstein, Fermi–Dirac, or Maxwell–Boltzmann statistics or parastatistics. For all these types of statistics, we find recursive relations for the partition function of a new statistical model of nuclear multifragmentation with electric charge and baryon number conservation, accounting for the internal degrees of freedom of the nuclear fragments. 相似文献
12.
We characterize all equivariant odd spectral triples for the quantum SU(2) group acting on its L
2-space and having a nontrivial Chern character. It is shown that the dimension of an equivariant spectral triple is at least three, and given any element of the K-homology group of SUq(2), there is an equivariant odd spectral triple of dimension 3 inducing that element. The method employed to get equivariant spectral triples in the quantum case is then used for classical SU(2), and we prove that for p < 4, there does not exist any equivariant spectral triple with nontrivial K-homology class and dimension p acting on the L
2-space.The first author would like to acknowledge support from the National Board of Higher Mathematics, India. 相似文献
13.
14.
D. P. Zhelobenko 《Acta Appl Math》2004,81(1):347-354
A special class of associative algebras is introduced and studied. A criteria of semisimplicity for suitable category of modules is obtained. 相似文献
15.
R. Grac M. Pugnet J.H. Collet B. Lambert C. De Matos H. L'Haridon A. Le Corre J.O. White 《Superlattices and Microstructures》1997,22(4):505-509
We report new results on the diffraction properties of photoinduced gratings in InGaAs/InGaAsP MQW structures. The original feature of this device is that the QWs are enclosed in an asymmetric Fabry–Perot microcavity in order to increase the diffraction efficiency. We observe oscillations in the diffraction efficiency due to resonant effects in the microcavity. The experimental spectra are compared with theory. Diffraction efficiency at 1.55 μm attains a maximum value of 2.7% at a write beam fluence of 260 μ J cm−2, and then decreases at higher fluences. We explain this phenomenon by an absorption saturation at high excitation. 相似文献
16.
17.
18.
Bernhard Heinemann 《Mathematical Logic Quarterly》1997,43(2):203-215
Based on a modification of Moss' and Parikh's topological modal language [8], we study a generalization of a weakly expressive fragment of a certain propositional modal logic of time. We define a bimodal logic comprising operators for knowledge and nexttime. These operators are interpreted in binary computation structures. We present an axiomatization of the set T of theorems valid for this class of semantical domains and prove – as the main result of this paper – its completeness. Moreover, the question of decidability of T is treated. 相似文献
19.
Using the path integral method we derive quantum wave function and quantum fluctuations of charge andcurrent in the mesoscopic RLC circuit. We find that the quantum fluctuation of charge decreases with time, oppositely,the quantum fluctuation of current increases with time monotonously. Therefore there is a squeezing effect in the circuit.If some more charge devices are used in the mesoscopic-damped circuit, the quantum noise can be reduced. We also findthat uncertainty relation of charge and current periodically varies with the period π/2 in the under-damped case. 相似文献
20.