全文获取类型
收费全文 | 54096篇 |
免费 | 8832篇 |
国内免费 | 4134篇 |
专业分类
化学 | 11004篇 |
晶体学 | 382篇 |
力学 | 11550篇 |
综合类 | 745篇 |
数学 | 15867篇 |
物理学 | 27514篇 |
出版年
2024年 | 96篇 |
2023年 | 569篇 |
2022年 | 1028篇 |
2021年 | 1385篇 |
2020年 | 1632篇 |
2019年 | 1424篇 |
2018年 | 1358篇 |
2017年 | 1867篇 |
2016年 | 2183篇 |
2015年 | 1741篇 |
2014年 | 2973篇 |
2013年 | 4250篇 |
2012年 | 3207篇 |
2011年 | 3859篇 |
2010年 | 3169篇 |
2009年 | 3671篇 |
2008年 | 3632篇 |
2007年 | 3630篇 |
2006年 | 3100篇 |
2005年 | 2846篇 |
2004年 | 2519篇 |
2003年 | 2235篇 |
2002年 | 2007篇 |
2001年 | 1703篇 |
2000年 | 1568篇 |
1999年 | 1322篇 |
1998年 | 1249篇 |
1997年 | 926篇 |
1996年 | 773篇 |
1995年 | 715篇 |
1994年 | 636篇 |
1993年 | 583篇 |
1992年 | 466篇 |
1991年 | 407篇 |
1990年 | 327篇 |
1989年 | 265篇 |
1988年 | 266篇 |
1987年 | 227篇 |
1986年 | 188篇 |
1985年 | 210篇 |
1984年 | 191篇 |
1983年 | 99篇 |
1982年 | 156篇 |
1981年 | 91篇 |
1980年 | 49篇 |
1979年 | 59篇 |
1978年 | 39篇 |
1977年 | 36篇 |
1976年 | 24篇 |
1973年 | 30篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
61.
LIU Jixue ZHANG Sanguo & CHEN Xiru Department of Statistics Finance University of Science Technology of China Hefei China Department of Mathematics Graduate School of Chinese Academy of Sciences Beijing China 《中国科学A辑(英文版)》2006,49(6):752-769
This paper studies the linear EV model when replicate observations are made only on independent variables. We construct the estimates of regression coefficients and prove the consistency and asymptotic normality under some proper conditions. Results obtained reveal the difference between the case where the independent and dependent variables are observed repeatedly and simultaneously and the case studied in this article. 相似文献
62.
63.
64.
65.
M. Gorkunov M. Lapine E. Shamonina K.H. Ringhofer 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,28(3):263-269
Effective magnetic properties of a composite meta-material consisting of periodically arranged circular conductive elements
are studied theoretically. A general expression for the effective bulk permeability is obtained with mutual effects and lattice
ordering being taken into account. The resonance frequency of the permeability is found to be strongly dependent on the size
and shape of the unit cell. Frequency dispersion of the permeability is studied with special attention paid to the frequency
range, where negative values of the permeability are possible. Corresponding recommendations for optimisation of the meta-materials
with negative permeability are made. The results are confirmed by numerical simulations of the finite structure behaviour
in an external magnetic field.
Received 19 April 2002 Published online 31 July 2002 相似文献
66.
67.
B. Dubrulle F. Hersant 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,26(3):379-386
We generalize an analogy between rotating and stratified shear flows. This analogy is summarized in Table 1. We use this analogy
in the unstable case (centrifugally unstable flow vs. convection) to compute the torque in Taylor-Couette configuration, as a function of the Reynolds number. At low Reynolds
numbers, when most of the dissipation comes from the mean flow, we predict that the non-dimensional torque G = T/ν2
L, where L is the cylinder length, scales with Reynolds number R and gap width η, G = 1.46η3/2(1 - η)-7/4
R
3/2. At larger Reynolds number, velocity fluctuations become non-negligible in the dissipation. In these regimes, there is no
exact power law dependence the torque versus Reynolds. Instead, we obtain logarithmic corrections to the classical ultra-hard (exponent 2) regimes: G = 0.50
. These predictions are found to be in excellent agreement with avail-able experimental data. Predictions for scaling of velocity
fluctuations are also provided.
Received 7 June 2001 and Received in final form 7 December 2001 相似文献
68.
A. Mielke 《Journal of statistical physics》1991,62(3-4):509-528
The magnetic properties of the one-dimensional Hubbard model with a hardcore interaction on a ring (periodic boundary conditions) are investigated. At finite temperatures it is shown to behave up to exponentially small corrections as a pure paramagnet. An explicit expression for the ground-state degeneracies is derived. The eigenstates of this model are used to perform a perlurbational treatment for large but finite interactions. In first order inU
1 an effective Hamiltonian for the one-dimensional Hubbard model is derived. It is the Hamiltonian of the one-dimensional Hcisenberg model with antiferromagnetic couplings between nearest neighbor spins. An asymptotic expansion for the ground-state energy is given. The results are valid for arbitrary densities of electrons. 相似文献
69.
We analyze diffusion from a periodic array of hemispherical droplets through a membrane. We find that the multiple sources do not interact strongly, even when the droplets are closely spaced, so that the flux through the membrane appears nearly additive. 相似文献
70.