全文获取类型
收费全文 | 39932篇 |
免费 | 1466篇 |
国内免费 | 1447篇 |
专业分类
化学 | 28507篇 |
晶体学 | 312篇 |
力学 | 779篇 |
综合类 | 10篇 |
数学 | 5543篇 |
物理学 | 7694篇 |
出版年
2023年 | 298篇 |
2022年 | 499篇 |
2021年 | 675篇 |
2020年 | 657篇 |
2019年 | 667篇 |
2018年 | 768篇 |
2017年 | 752篇 |
2016年 | 1462篇 |
2015年 | 1174篇 |
2014年 | 1252篇 |
2013年 | 2692篇 |
2012年 | 2941篇 |
2011年 | 3172篇 |
2010年 | 1829篇 |
2009年 | 1865篇 |
2008年 | 2454篇 |
2007年 | 2393篇 |
2006年 | 2089篇 |
2005年 | 1982篇 |
2004年 | 2069篇 |
2003年 | 1494篇 |
2002年 | 1371篇 |
2001年 | 863篇 |
2000年 | 726篇 |
1999年 | 563篇 |
1998年 | 461篇 |
1997年 | 360篇 |
1996年 | 441篇 |
1995年 | 326篇 |
1994年 | 289篇 |
1993年 | 341篇 |
1992年 | 288篇 |
1991年 | 200篇 |
1990年 | 192篇 |
1989年 | 162篇 |
1988年 | 161篇 |
1987年 | 151篇 |
1986年 | 148篇 |
1985年 | 235篇 |
1984年 | 205篇 |
1983年 | 161篇 |
1982年 | 142篇 |
1981年 | 144篇 |
1980年 | 111篇 |
1979年 | 118篇 |
1978年 | 99篇 |
1977年 | 96篇 |
1976年 | 90篇 |
1975年 | 88篇 |
1973年 | 92篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
Miroslav Menšík 《Czechoslovak Journal of Physics》1998,48(4):469-475
A time solution of the excimer-ion pair system is presented here with a special attention to the time asymptote.
Presented at the Czech-Israeli-German Symposium “Dynamical Processes in Condensed Molecular Systems”, Prague, Czech Republic,
26–30 May 1997.
This work was supported by the grant No. C 1050601 of the Grant Agency of the Academy of Sciences of the Czech Republic. 相似文献
72.
73.
A special two-sided condition for the incremental magnetic reluctivity is introduced which guarantees the unique existence of both the weak and the approximate solutions of the nonlinear stationary magnetic field distributed on a region composed of different media, as well as a certain estimate of the error between the two solutions. The condition, being discussed from the physical as well as the mathematical point of view, can be easily verified and is fulfilled for various magnetic reluctivity models used in electrotechnical practice. 相似文献
74.
We study the spectrum and eigenmodes of the QCD Dirac operator in a gauge background given by an instanton liquid model (ILM) at temperatures around the chiral phase transition. Generically we find the Dirac eigenvectors become more localized as the temperature is increased. At the chiral phase transition, both the low lying eigenmodes and the spectrum of the QCD Dirac operator undergo a transition to localization similar to the one observed in a disordered conductor. This suggests that Anderson localization is the fundamental mechanism driving the chiral phase transition. We also find an additional temperature dependent mobility edge (separating delocalized from localized eigenstates) in the bulk of the spectrum which moves toward lower eigenvalues as the temperature is increased. In both regions, the origin and the bulk, the transition to localization exhibits features of a 3D Anderson transition including multifractal eigenstates and spectral properties that are well described by critical statistics. Similar results are obtained in both the quenched and the unquenched case though the critical temperature in the unquenched case is lower. Finally we argue that our findings are not in principle restricted to the ILM approximation and may also be found in lattice simulations. 相似文献
75.
76.
Marek Pękała Jan Mucha Benedicte Vertruyen Rudi Cloots Marcel Ausloos 《Journal of magnetism and magnetic materials》2006
Samples of La0.7Ca0.3Mn1−xGaxO3 with x=0, 0.025, 0.05 and 0.10 were prepared by standard solid-state reaction. They were first characterized chemically, including the microstructure. The magnetic properties and various transport properties, i.e. the electrical resistivity, magnetoresistivity (for a field below 8 T), thermoelectric power and thermal conductivity measured each time on the same sample, are reported. The markedly different behaviour of the x=0.1 sample from those with a smaller Ga content, is discussed. The dilution of the Mn3+/Mn4+ interactions with Ga doping considerably reduces the ferromagnetic double exchange interaction within the manganese lattice leading to a decrease of the Curie temperature. The polaron binding energy varies from 224 to 243 meV with increased Ga doping. 相似文献
77.
Symmetric Hilbert spaces such as the bosonic and the fermionic Fock spaces over some lsquo;one particle space’ are formed by certain symmetrization procedures performed on the full Fock space. We investigate alternative ways of symmetrization
by building on Joyal's notion of a combinatorial species. Any such species F gives rise to an endofunctor of the category of Hilbert spaces with contractions mapping a Hilbert space to a symmetric Hilbert space with the same symmetry as the species F. A general framework for annihilation and creation operators on these spaces is developed, and compared to the generalised
Brownian motions of R. Speicher and M. Bożejko. As a corollary we find that the commutation relation with admits a realization on a symmetric Hilbert space whenever f has a power series with infinite radius of convergence and positive coefficients.
Received: 7 April 2000; in final form: 28 November 2000 / Published online: 19 October 2001 相似文献
78.
79.
80.
Lubomír Kubáček 《Mathematica Slovaca》2007,57(1):59-82
In some situations estimates of unknown parameters must be corrected by additional measurements. It is in principle no problem
to calculate the corrected estimates, however, it is of more interest to find formulae for correction itself. The formulae
enable us to design an additional experiment and to judge its usefulness.
The aim of the paper is to find such formulae for several situations.
Supported by the grant of the Council of Czech Government MSM 6 198 959 214. 相似文献