全文获取类型
收费全文 | 21801篇 |
免费 | 2197篇 |
国内免费 | 1602篇 |
专业分类
化学 | 13691篇 |
晶体学 | 263篇 |
力学 | 947篇 |
综合类 | 151篇 |
数学 | 3601篇 |
物理学 | 6947篇 |
出版年
2023年 | 262篇 |
2022年 | 456篇 |
2021年 | 494篇 |
2020年 | 655篇 |
2019年 | 638篇 |
2018年 | 610篇 |
2017年 | 579篇 |
2016年 | 931篇 |
2015年 | 1043篇 |
2014年 | 1127篇 |
2013年 | 1646篇 |
2012年 | 1643篇 |
2011年 | 1764篇 |
2010年 | 1258篇 |
2009年 | 1172篇 |
2008年 | 1325篇 |
2007年 | 1157篇 |
2006年 | 981篇 |
2005年 | 785篇 |
2004年 | 653篇 |
2003年 | 545篇 |
2002年 | 499篇 |
2001年 | 355篇 |
2000年 | 369篇 |
1999年 | 284篇 |
1998年 | 212篇 |
1997年 | 203篇 |
1996年 | 182篇 |
1995年 | 174篇 |
1994年 | 143篇 |
1993年 | 157篇 |
1992年 | 128篇 |
1991年 | 119篇 |
1990年 | 124篇 |
1989年 | 105篇 |
1988年 | 119篇 |
1987年 | 94篇 |
1986年 | 94篇 |
1985年 | 114篇 |
1984年 | 122篇 |
1983年 | 90篇 |
1982年 | 105篇 |
1981年 | 106篇 |
1980年 | 99篇 |
1979年 | 116篇 |
1978年 | 110篇 |
1977年 | 92篇 |
1976年 | 111篇 |
1975年 | 106篇 |
1974年 | 101篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
61.
The dynamical system approach is applied to the study of dynamics of multidimensional cosmological models with topology FRW ×T
D (D-dimensional torus) in the presence of high-temperature quantum effects. The stability methods developed in the paper of Szydowski (Gen. Rel. Grav.,20, 221, 1988) are used in the analysis of typical states of the metric in the neighborhood of singularities and for large time values. The problems of dynamical dimensional reduction, structure of singularities, isotropization, etc., are discussed in this context. 相似文献
62.
The paper deals with the regime of advanced Bénard instabilities (described usually by the Lorenz system) in a more general system formulated firstly by Obukhov. It has been shown that triplet co-operation leads to characteristic courses where some new regularities occur. 相似文献
63.
K. Rohlena K. Mašek E. G. Balabanova I. Paulička 《Czechoslovak Journal of Physics》1988,38(6):622-637
Systematic calculations of maximum inversion were performed for iodine photodissociation laser in dependence on the mixture composition. The flash-lamp radiation was modelled as emanating from an optically thin Xe plasma. Duration of the pumping pulse is about 300 s. The sensitivity of the model to the values of kinetic constants was also tested. 相似文献
64.
VI. Sedláček 《Czechoslovak Journal of Physics》1988,38(5):465-469
The formation of slip bands is the main mechanism of cyclic deformation in pure Al. Their density, orientation and heights in polycrystalline Al were investigated during cycling. Types, sizes and densities of precipitates are responsible for the mode of cyclic deformation in AlCu4 pure alloy. In technical Al alloys intermetallic phases have detrimental effects on deformation homogeneity and largely govern the fatigue mechanism of the material and especially microcrack initiation. 相似文献
65.
D. Macko V. Hajko Jr. J. Billy P. Makroczy V. Kavečanský O. Hudák 《Czechoslovak Journal of Physics》1988,38(12):1383-1386
Quasicrystalline Al-14 at. % Mn alloy was prepared by melt-spinning and its structural and electrical properties were studied. This alloy consists of icosahedral grains with sizes from 1 to 4 m and of crystalline aluminium phase. The electrical resistivity was almost temperature independent with a value of about 765 n gWm at 4·2 K. 相似文献
66.
The time dependence of the electron distribution function in helium afterglow, for pressures of 60–260 Pa, is calculated for the case in which metastable-metastable reactions are present. The time variation of the shape of the distribution function shows that careful consideration must be made of the time derivative of the distribution function in the Boltzmann equation for the calculation of the rate constant of such reactions from experimentally determined distribution function. 相似文献
67.
68.
Petr Šeba 《Letters in Mathematical Physics》1988,16(1):51-59
The method of complex scaling, usually used in atomic and molecular resonance calculations, is generalized to the Dirac equation. It is shown that Dirac resonances are associated with nonreal eigenvalues of the scaled Dirac Hamiltonian. The perturbation theory for the resonance parameters is also discussed. 相似文献
69.
Mladen Pavičić 《Foundations of Physics》1989,19(8):999-1016
Unified quantum logic based on unified operations of implication is formulated as an axiomatic calculus. Soundness and completeness are demonstrated using standard algebraic techniques. An embedding of quantum logic into a new modal system is carried out and discussed.On leave of absence from Department of Mathematics, University of Zagreb, Pot. Pret. 165, YU-41001 Zagreb, Yugoslavia. 相似文献
70.
J. Požela A. Namajūnas A. Tamaševičius J. Ulbikas 《Applied Physics A: Materials Science & Processing》1989,48(2):181-188
A method for quantitative characterization of chaotic dynamical systems is discussed. An electronic instrument for determining the number of independent variablesk
*, involved in the motion, is described. It allows one to obtain these in real time from a single observable. The suggested technique has been applied to quantification of strange attractors underlying chaotic instabilities in semi-insulating GaAsCr, and n-Ge, irradiated with high energy electrons. In n-Ge, for instance, the measured numbersk
* range from 2 to 4 depending on control parameters. These measurements reveal the highly deterministic nature of the observed chaotic oscillations. The physical mechanisms responsible for the current instabilities and chaotic behaviour are discussed. 相似文献