全文获取类型
收费全文 | 43777篇 |
免费 | 6347篇 |
国内免费 | 4894篇 |
专业分类
化学 | 31193篇 |
晶体学 | 547篇 |
力学 | 1611篇 |
综合类 | 285篇 |
数学 | 3988篇 |
物理学 | 17394篇 |
出版年
2024年 | 91篇 |
2023年 | 558篇 |
2022年 | 1562篇 |
2021年 | 1474篇 |
2020年 | 1612篇 |
2019年 | 1505篇 |
2018年 | 1323篇 |
2017年 | 1549篇 |
2016年 | 1833篇 |
2015年 | 1682篇 |
2014年 | 2120篇 |
2013年 | 3218篇 |
2012年 | 2539篇 |
2011年 | 2847篇 |
2010年 | 2321篇 |
2009年 | 2761篇 |
2008年 | 2753篇 |
2007年 | 2753篇 |
2006年 | 2578篇 |
2005年 | 2319篇 |
2004年 | 2277篇 |
2003年 | 1802篇 |
2002年 | 2047篇 |
2001年 | 1271篇 |
2000年 | 1174篇 |
1999年 | 872篇 |
1998年 | 815篇 |
1997年 | 674篇 |
1996年 | 636篇 |
1995年 | 607篇 |
1994年 | 540篇 |
1993年 | 375篇 |
1992年 | 389篇 |
1991年 | 244篇 |
1990年 | 207篇 |
1989年 | 198篇 |
1988年 | 185篇 |
1987年 | 143篇 |
1986年 | 120篇 |
1985年 | 105篇 |
1984年 | 100篇 |
1983年 | 37篇 |
1982年 | 83篇 |
1981年 | 112篇 |
1980年 | 120篇 |
1979年 | 121篇 |
1978年 | 101篇 |
1977年 | 72篇 |
1976年 | 70篇 |
1973年 | 31篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
We consider a quark model based on QCD scale anomaly in which the quarks move in the field of an effective glueball field.
Hadrons correspond to solitonic bags of higher energy density in a nonperturbative sea of condensed gluons. We calculate the
static properties of nucleon in this model and find that the nucleon mass is far too large (2.4–4 GeV) and the proton charge
radius (0.37–0.54 fm) is low. The proton gyromagnetic ratio and gA/gv are in reasonable agreement with the experimental numbers. 相似文献
92.
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
93.
MATLAB/SIMULINK在电力系统仿真中的应用 总被引:2,自引:0,他引:2
介绍了Matlab/Simulink仿真工具在电力系统仿真中的应用方法. 相似文献
94.
95.
96.
E. L. Kristallovich A. G. Eshimbetov N. D. Chuvylkin L. I. Belen'kii Kh. M. Shakhidoyatov 《Chemistry of Natural Compounds》2003,39(5):495-500
The principal types of electronic transitions in absorption spectra of deoxyvasicinone and its 6-amino- and 6-nitro-derivatives were determined by analyzing the electron-density distributions in excited states calculated using ZINDO/S. 相似文献
97.
A. Hichri S. Jaziri R. Ferreira 《Physica E: Low-dimensional Systems and Nanostructures》2004,24(3-4):234-243
We demonstrate coupling and entangling of quantum states in a pair of vertically aligned self assembled quantum dots by studying the dynamics of two interacting electrons driven by external electric field. The present entanglement involves the spatial degree of freedom for the two electrons system. We show that system of two interacting electrons initially delocalized (localized each in one dot) oscillate slowly in response to electric field, since the strong Coulomb repulsion makes them behaving so. We use an explicit formula for the entanglement of formation of two qubit in terms of the concurrence of the density operator. In ideal situations, entangled quantum states would not decohere during processing and transmission of quantum information. However, real quantum systems will inevitably be influenced by surrounding environments. We discuss the degree of entanglement of this system in which we introduce the decoherence effect caused by the acoustic phonon. In this entangled states proposal, the decohering time depends on the external parameters. 相似文献
98.
The title compound is a centrosymmetric dimer with each cadmium in a distorted CdS5 square pyramidal geometry. The Cd–S bond distances range from 2.5626(11) to 2.8459(11) Å. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
99.
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