全文获取类型
收费全文 | 44585篇 |
免费 | 5085篇 |
国内免费 | 2457篇 |
专业分类
化学 | 23065篇 |
晶体学 | 687篇 |
力学 | 598篇 |
综合类 | 686篇 |
数学 | 6594篇 |
物理学 | 20497篇 |
出版年
2023年 | 279篇 |
2022年 | 859篇 |
2021年 | 1592篇 |
2020年 | 859篇 |
2019年 | 925篇 |
2018年 | 731篇 |
2017年 | 926篇 |
2016年 | 1130篇 |
2015年 | 1200篇 |
2014年 | 1702篇 |
2013年 | 2934篇 |
2012年 | 2036篇 |
2011年 | 2181篇 |
2010年 | 1896篇 |
2009年 | 2435篇 |
2008年 | 2742篇 |
2007年 | 2792篇 |
2006年 | 2248篇 |
2005年 | 1597篇 |
2004年 | 1446篇 |
2003年 | 1468篇 |
2002年 | 3897篇 |
2001年 | 1621篇 |
2000年 | 1160篇 |
1999年 | 982篇 |
1998年 | 918篇 |
1997年 | 734篇 |
1996年 | 740篇 |
1995年 | 672篇 |
1994年 | 650篇 |
1993年 | 639篇 |
1992年 | 608篇 |
1991年 | 394篇 |
1990年 | 347篇 |
1989年 | 296篇 |
1988年 | 303篇 |
1987年 | 225篇 |
1986年 | 225篇 |
1985年 | 334篇 |
1984年 | 246篇 |
1983年 | 145篇 |
1982年 | 299篇 |
1981年 | 470篇 |
1980年 | 429篇 |
1979年 | 466篇 |
1978年 | 368篇 |
1977年 | 279篇 |
1976年 | 238篇 |
1974年 | 74篇 |
1973年 | 151篇 |
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
31.
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
32.
Q. Sun Q. Wang X.G. Gong V. Kumar Y. Kawazoe 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,18(1):77-81
We report results of the atomic and electronic structures of Al7C cluster using ab initio molecular dynamics with ultrasoft pseudopotentials and generalized gradient approximation. The lowest energy structure is
found to be the one in which carbon atom occupies an interstitial position in Al7 cluster. The electronic structure shows that the recent observation [Chem. Phys. Lett. 316, 31 (2000)] of magic behavior of Al7C- cluster is due to a large highest occupied and lowest unoccupied molecular orbital (HOMO-LUMO) gap which makes Al7C- chemically inert. These results have further led us to the finding of a new neutral magic cluster Al7N which has the same number of valence electrons as in Al7C- and a large HOMO-LUMO gap of 1.99 eV. Further, calculations have been carried out on (Al7N)2 to study interaction between magic clusters.
Received 28 July 2001 相似文献
33.
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
34.
S.-Y. Sheu D.-Y. Yang H.L. Selzle E.W. Schlag 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,20(3):557-563
Charge transport is one important example of signal transduction in a protein which is responsible for action at a distance,
and is a fundamental process in biochemical action. A model is presented in which electronic effects interact with motional
processes to combine into a bifunctional model. This model is investigated with new detailed molecular dynamics calculations
and successfully explains such action at a distance.
Received 1st February 2002 / Received in final form 26 May 2002 Published online 13 September 2002 相似文献
35.
36.
介绍了新颖的纳米结构亚波长光学器件的特点,从器件的基本功能特性和工作机理两个方面详细讨论了其应用状况,并阐述了纳米制造技术对亚波长光学器件发展的重要推动作用及这一领域今后的研究热点。 相似文献
37.
38.
Let G=(V(G),E(G)) be a graph. A (n,G, λ)‐GD is a partition of the edges of λKn into subgraphs (G‐blocks), each of which is isomorphic to G. The (n,G,λ)‐GD is named as graph design for G or G‐decomposition. The large set of (n,G,λ)‐GD is denoted by (n,G,λ)‐LGD. In this work, we obtain the existence spectrum of (n,P3,λ)‐LGD. © 2002 Wiley Periodicals, Inc. J Combin Designs 10: 151–159, 2002; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/jcd.10008 相似文献
39.
40.
本文采用求解Schroedinger方程和数值计算方法,研究了Ⅴ-型三能级原子与双模奇偶纠缠相干光场相互作用系统的光子统计性质,结果表明:此性质与双模奇偶纠缠相干光场的纠缠程度、失谐量、原子的初态以及双模光的平均光子数相关联. 相似文献