全文获取类型
收费全文 | 731篇 |
免费 | 52篇 |
国内免费 | 2篇 |
专业分类
化学 | 562篇 |
晶体学 | 1篇 |
力学 | 23篇 |
数学 | 81篇 |
物理学 | 118篇 |
出版年
2023年 | 9篇 |
2022年 | 9篇 |
2021年 | 11篇 |
2020年 | 20篇 |
2019年 | 13篇 |
2018年 | 23篇 |
2017年 | 5篇 |
2016年 | 38篇 |
2015年 | 22篇 |
2014年 | 28篇 |
2013年 | 37篇 |
2012年 | 60篇 |
2011年 | 80篇 |
2010年 | 39篇 |
2009年 | 47篇 |
2008年 | 64篇 |
2007年 | 70篇 |
2006年 | 55篇 |
2005年 | 54篇 |
2004年 | 26篇 |
2003年 | 26篇 |
2002年 | 24篇 |
2001年 | 5篇 |
2000年 | 3篇 |
1999年 | 2篇 |
1998年 | 2篇 |
1997年 | 1篇 |
1996年 | 2篇 |
1995年 | 1篇 |
1992年 | 2篇 |
1991年 | 2篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1983年 | 2篇 |
1981年 | 1篇 |
排序方式: 共有785条查询结果,搜索用时 31 毫秒
81.
Farouk Benmeddour Fabien Treyssède Laurent Laguerre 《International Journal of Solids and Structures》2011,48(5):764-774
A three dimensional (3D) hybrid method combining the classical finite element (FE) method with the semi-analytical finite element (SAFE) technique is developed. This hybrid method is employed to study the interaction of guided waves with non-axisymmetric damages in cylinders. The near field surrounding the damage is analysed with the 3D FE method. The solution is expanded into sums of guided modes on both inlet and outlet cross-sections. Such eigenmode expansions enable separation into ingoing and outgoing waves, i.e., incident, reflected and transmitted waves. Using the SAFE method, elastic guided modes are then computed at the aforementioned cross-sections thus reducing the analysis to two dimensions (2D). The amplitudes of the incident modes are imposed, whereas those of the scattered modes are determined by solving the global system of the 3D hybrid FE-SAFE model. In this paper, a formula is proposed for the calculation of eigenforces and modal power flows from eigendisplacements and SAFE matrices. This has the advantage of simplifying the post-process of load eigenvectors in hybrid FE-SAFE methods. Results obtained for a vertical free-end cylinder are in good agreement with those published in the literature. Moreover, first results of the interaction of the fundamental compressional, flexural and torsional Pochhammer–Chree modes with non-axisymmetric vertical cracks are obtained and discussed. Then, the interactions of the fundamental compressional mode with oblique free-ends and cracks are briefly addressed. The power balance is shown to be satisfied with a good accuracy. 相似文献
82.
83.
84.
Budarin V Clark JH Deswarte FE Hardy JJ Hunt AJ Kerton FM 《Chemical communications (Cambridge, England)》2005,(23):2903-2905
Expansion of native corn starch produces a high surface area mesoporous material capable of acting as a novel stationary phase for separating various mixtures of compounds. 相似文献
85.
Necessary and Sufficient Conditions to be an Eigenvalue for Linearly Recurrent Dynamical Cantor Systems 总被引:2,自引:0,他引:2
Bressaud Xavier; Durand Fabien; Maass Alejandro 《Journal London Mathematical Society》2005,72(3):799-816
Necessary and sufficient conditions are given for linearly recurrentCantor dynamical systems to have measurable and continuous eigenfunctions.Also an example of a linearly recurrent system with a nontrivialKronecker factor and a trivial maximal equicontinuous factoris constructed explicitly. 相似文献
86.
87.
Bruneval F Vast N Reining L Izquierdo M Sirotti F Barrett N 《Physical review letters》2006,97(26):267601
State-of-the-art theoretical methods fail in describing the optical absorption spectrum, band gap, and optical onset of Cu(2)O. We have extended a recently proposed self-consistent quasiparticle approach, based on the GW approximation, to the calculation of optical spectra, including excitonic effects. The band structure compares favorably with our present angle-resolved photoemission measurements. The excitonic effects based on these realistic band structure and screening provide a reliable optical absorption spectrum, which allows for a revised interpretation of its main structures. 相似文献
88.
Weissker HC Serrano J Huotari S Bruneval F Sottile F Monaco G Krisch M Olevano V Reining L 《Physical review letters》2006,97(23):237602
We present an investigation of the dynamic structure factor and of the dielectric function epsilonM(Q,omega) of the prototypical semiconductor silicon for finite momentum transfer, combining inelastic x-ray scattering experiments and ab initio calculations. In contrast with optical spectra, for finite momentum transfer time-dependent density-functional theory in the adiabatic local-density approximation together with lifetime broadening describes the physics of valence excitations correctly. Major structures in the spectra, governed by short-range crystal and exchange-correlation local-field effects, are strongly influenced by a mixing of transitions of positive and negative energies, in striking difference to spectra for vanishing momentum transfer. This mixing gives rise to a pronounced Fano asymmetry. 相似文献
89.
We have investigated the vapor phase growth of Au on SrTiO3(001)-(2 x 1) substrates by UHV scanning tunneling microscopy. Submonolayer (ML) coverages below 300 degrees C wet the surface as disordered metastable 2D islands. Beyond 0.75 ML fcc nanocrystals with a (111) interface are nucleated and ripen by dewetting the surrounding layer. Some multiply twinned fivefold symmetric clusters are also created. Above 400 degrees C dewetting occurs for all coverages and the surface is only populated by nanocrystals and fivefold clusters. A planar ground state configuration for small Au clusters and a higher interface energy for crystals than for wetted 2D ML films explains these results. 相似文献
90.
Bi-isoquinoline can be used as a building block to prepare a new family of non-sterically hindering chelates, including a macrocyclic system; the endocyclic nature of the ligands has been confirmed by the X-ray structure of an octahedral tris-chelate iron(II) complex, which shows that the three chelates are easily accommodated in the coordination sphere of the metal in spite of their crescent shape. 相似文献