全文获取类型
收费全文 | 1209篇 |
免费 | 82篇 |
国内免费 | 25篇 |
专业分类
化学 | 172篇 |
晶体学 | 7篇 |
力学 | 43篇 |
综合类 | 27篇 |
数学 | 777篇 |
物理学 | 290篇 |
出版年
2023年 | 5篇 |
2022年 | 22篇 |
2021年 | 33篇 |
2020年 | 21篇 |
2019年 | 27篇 |
2018年 | 28篇 |
2017年 | 31篇 |
2016年 | 52篇 |
2015年 | 18篇 |
2014年 | 41篇 |
2013年 | 66篇 |
2012年 | 37篇 |
2011年 | 55篇 |
2010年 | 42篇 |
2009年 | 45篇 |
2008年 | 159篇 |
2007年 | 129篇 |
2006年 | 75篇 |
2005年 | 61篇 |
2004年 | 48篇 |
2003年 | 34篇 |
2002年 | 32篇 |
2001年 | 34篇 |
2000年 | 19篇 |
1999年 | 18篇 |
1998年 | 17篇 |
1997年 | 17篇 |
1996年 | 16篇 |
1995年 | 15篇 |
1994年 | 6篇 |
1993年 | 13篇 |
1992年 | 9篇 |
1991年 | 9篇 |
1990年 | 9篇 |
1989年 | 3篇 |
1988年 | 4篇 |
1987年 | 5篇 |
1986年 | 9篇 |
1985年 | 5篇 |
1984年 | 9篇 |
1983年 | 6篇 |
1982年 | 5篇 |
1981年 | 6篇 |
1979年 | 5篇 |
1978年 | 4篇 |
1977年 | 5篇 |
1976年 | 2篇 |
1974年 | 1篇 |
1972年 | 1篇 |
1969年 | 1篇 |
排序方式: 共有1316条查询结果,搜索用时 46 毫秒
71.
展望21世纪风能的利用与发展 总被引:6,自引:0,他引:6
本介绍了国内外风能利用的现状,并对我国未来风能的利用与发展提出了很多建设性的意见,诸如:发展目标的确立,政策、法规体系的建立,技术性能的提高及新产品的开发,经济鼓励政策及其实施,产业化体系的建设等。 相似文献
72.
73.
H. Böhm J. Freyer M. Claassen W. Harth T. Bauer 《International Journal of Infrared and Millimeter Waves》1998,19(4):587-593
Investigations of GaAs-IMPATT diodes as self-pumped frequency doublers are carried out both, theoretically and experimentally. Optimization criterions are specified and first experimental results are presented. 1 mW output power has been achieved in the harmonic mode at 210 GHz. 相似文献
74.
H. Shigematsu 《Journal of statistical physics》1993,71(5-6):981-1002
Fluctuation of the average spin for one-dimensional Ising spins with nearest neighbor interactions are studied. The distribution function for the average spin is calculated for a finite volume, finite temperature, and finite magnetic field. As the volume increases and the temperature diminishes at zero magnetic field, there are two limits in which the probability distribution shows quite different behaviors: in the thermodynamic limit as the volume goes to infinity for finite temperature, small deviations of the fluctuations are described by a Gaussian distribution, and in the limit as the temperature vanishes for a finite volume, the ground states are realized with probability one. The crossover between these limits is analyzed via a ratio of the correlation length to the volume. The helix-coil transition in a polypeptide is discussed as an application. 相似文献
75.
76.
77.
J.W. Gadzuk 《Chemical physics letters》1981,80(1):5-10
The vibrational spectrum of an atom or molecule adsorbed on a metallic surface is influenced by the dynamic interaction between the localized oscillator and the continuum of electron-hole pair excitations in the solid. Features of an exactly soluble model for this interacting system are presented, the local spectral function is obtained in terms of calculable level shift and broadening functions, and some prototypical numerical results are displayed and discussed. 相似文献
78.
Ilya?KuselmanEmail author Alexander?Weisman Wolfhard?Wegscheider 《Accreditation and quality assurance》2003,8(11):530-531
The current situation in the pharmaceutical industry is discussed, when the traceability of measurement (analytical) results to certified values of pharmacopoeial reference standards is required, without evaluating their uncertainties. It is shown that the evaluation of measurement uncertainty is necessary for understanding the level of confidence of the analytical results and their comparability, particularly during preparation and characterisation of the reference standards.Papers published in this section do not necessarily reflect the opinion of the Editors, the Editorial Board and the Publisher. Apart from exceptional circumstances, they are not submitted to the usual referee procedure and go essentially unaltered. 相似文献
79.
80.
M. Porfiri E. M. Bollt D. J. Stilwell 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,57(4):481-486
Opinion compromise models can give insight into how groups of individuals may either come to form
consensus or clusters of opinion groups, corresponding to parties. We consider models where randomly
selected individuals interact pairwise. If the opinions of the interacting agents are not within a certain confidence
threshold, the agents retain their own point of view. Otherwise, they constructively dialogue and smooth their
opinions. Persuasible agents are inclined to compromise with interacting individuals. Stubborn individuals slightly
modify their opinion during the interaction. Collective states for persuasible societies include extremist minorities,
which instead decline in stubborn societies. We derive a mean field approximation for the compromise model in stubborn
populations. Bifurcation and clustering analysis of this model compares favorably with Monte Carlo analysis found in
the literature. 相似文献