全文获取类型
收费全文 | 998篇 |
免费 | 40篇 |
国内免费 | 1篇 |
专业分类
化学 | 630篇 |
晶体学 | 2篇 |
力学 | 17篇 |
数学 | 155篇 |
物理学 | 235篇 |
出版年
2023年 | 14篇 |
2022年 | 15篇 |
2021年 | 15篇 |
2020年 | 19篇 |
2019年 | 28篇 |
2018年 | 23篇 |
2017年 | 11篇 |
2016年 | 35篇 |
2015年 | 31篇 |
2014年 | 30篇 |
2013年 | 30篇 |
2012年 | 60篇 |
2011年 | 56篇 |
2010年 | 47篇 |
2009年 | 36篇 |
2008年 | 41篇 |
2007年 | 38篇 |
2006年 | 40篇 |
2005年 | 35篇 |
2004年 | 28篇 |
2003年 | 24篇 |
2002年 | 17篇 |
2001年 | 12篇 |
2000年 | 18篇 |
1999年 | 10篇 |
1998年 | 9篇 |
1997年 | 9篇 |
1996年 | 9篇 |
1995年 | 14篇 |
1994年 | 14篇 |
1993年 | 12篇 |
1992年 | 6篇 |
1991年 | 12篇 |
1990年 | 9篇 |
1989年 | 6篇 |
1988年 | 10篇 |
1987年 | 9篇 |
1985年 | 6篇 |
1984年 | 14篇 |
1982年 | 7篇 |
1981年 | 9篇 |
1980年 | 10篇 |
1979年 | 8篇 |
1978年 | 8篇 |
1977年 | 11篇 |
1976年 | 6篇 |
1975年 | 8篇 |
1974年 | 10篇 |
1931年 | 7篇 |
1928年 | 6篇 |
排序方式: 共有1039条查询结果,搜索用时 15 毫秒
51.
52.
53.
Given a precompact subset of a type Banach space , where , we prove that for every and all
holds, where is the absolutely convex hull of and denotes the dyadic entropy number. With this inequality we show in particular that for given and with for all the inequality holds true for all . We also prove that this estimate is asymptotically optimal whenever has no better type than . For this answers a question raised by Carl, Kyrezi, and Pajor which has been solved up to now only for the Hilbert space case by F. Gao.
holds, where is the absolutely convex hull of and denotes the dyadic entropy number. With this inequality we show in particular that for given and with for all the inequality holds true for all . We also prove that this estimate is asymptotically optimal whenever has no better type than . For this answers a question raised by Carl, Kyrezi, and Pajor which has been solved up to now only for the Hilbert space case by F. Gao.
54.
Jakob J. Keller 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》1996,47(6):821-836
Introducing a vector potential, that is based on a pair of stream functions, and a velocity potential, antisymmetric equations for the stream functions are derived with the help of a variational principle. It is found that the equations are in a suitable form to investigate flows with helical symmetry, and, for example, to connect upstream axisymmetric flows with downstream helical flows. The special case of a transition from an upstream solid-body vortex to a downstream helical flow is investigated in detail. Furthermore, the stream-function equations are particularly useful to investigate general small-amplitude inertia waves on vortex flows. Time-dependent helical flows that are time-independent in a suitably rotating frame of reference can also be discussed with the proposed method. 相似文献
55.
J.J. Neve C.F.J. de Meijer F.A.P. Blom 《Journal of Physics and Chemistry of Solids》1981,42(11):975-980
Shubnikov-de Haas oscillations in the transverse magnetoresistance of single-crystalline n-type CdSnAs2 have been recorded at temperatures between 2 and 25 K in magnetic fields up to 5T. The electron concentration of the samples ranged from 2 × 1017 to 2 × 1018 cm?3. The angular dependences of the oscillation periods and cyclotron effective masses showed that the conduction band exhibits an energy dependent anisotropy, obeying the Kildal band structure model. For the low-temperature values of the band parameters we found: a band gap Eg = 0.30 eV, a spin-orbit splitting Δ = 0.50 eV, a crystal field splitting parameter δ = ?0.09 eV, and an interband matrix element P = 8.5 × 10?8eV cm. This simple four-level model was found to be not adequate to describe quantitatively the observed electronic effective g-factor for a sample with low electron concentration. 相似文献
56.
We derive constraints on the asymptotic behaviour of total cross sections which follow from dispersion relations and measured real parts of the forward scattering amplitudes. For πN and pp scattering, these constraints are calculated using recent results from FNAL and Serpukhov. The relation to other methods is discussed. 相似文献
57.
Force constants for CO2 have been calculated using SCF and CI potential surfaces. A large error for the stretch-stretch interaction force constant (K12) which occurs in the SCF calculation is significantly reduced by the Cltreatment. 相似文献
58.
Jakob Yngvason 《Communications in Mathematical Physics》1973,34(4):315-333
It is shown that every continuous linear functional on the field algebra can be defined by a vector in the Hilbert space of some representation of the algebra. The functionals which can be written as a difference of positive ones are characterized. By an example it is shown that a positive functional on a subalgebra does not always have an extension to a positive functional on the whole algebra. 相似文献
59.
60.
M. Diehl Th Feldmann R. Jakob P. Kroll 《The European Physical Journal C - Particles and Fields》2005,39(1):1-39
We present a simple empirical parameterization of the x- and t-dependence of generalized parton distributions at zero skewness, using forward parton distributions as input. A fit to experimental data for the Dirac, Pauli and axial form factors of the nucleon allows us to discuss quantitatively the interplay between longitudinal and transverse partonic degrees of freedom in the nucleon (nucleon tomography). In particular we obtain the transverse distribution of valence quarks at given momentum fraction x. We calculate various moments of the distributions, including the form factors that appear in the handbag approximation to wide-angle Compton scattering. This allows us to estimate the minimal momentum transfer required for reliable predictions in that approach to be around
. We also evaluate the valence contributions to the energy-momentum form factors entering Jis sum rule.Received: 16 September 2004, Revised: 15 October 2004, Published online: 17 December 2004 相似文献