全文获取类型
收费全文 | 1999篇 |
免费 | 59篇 |
专业分类
化学 | 1120篇 |
晶体学 | 25篇 |
力学 | 35篇 |
数学 | 315篇 |
物理学 | 563篇 |
出版年
2022年 | 14篇 |
2021年 | 17篇 |
2020年 | 17篇 |
2019年 | 32篇 |
2018年 | 62篇 |
2017年 | 38篇 |
2016年 | 119篇 |
2015年 | 76篇 |
2014年 | 94篇 |
2013年 | 223篇 |
2012年 | 73篇 |
2011年 | 109篇 |
2010年 | 75篇 |
2009年 | 74篇 |
2008年 | 95篇 |
2007年 | 69篇 |
2006年 | 77篇 |
2005年 | 59篇 |
2004年 | 62篇 |
2003年 | 56篇 |
2002年 | 34篇 |
2001年 | 38篇 |
2000年 | 27篇 |
1999年 | 22篇 |
1998年 | 22篇 |
1997年 | 28篇 |
1996年 | 17篇 |
1995年 | 20篇 |
1994年 | 12篇 |
1993年 | 14篇 |
1992年 | 13篇 |
1991年 | 19篇 |
1990年 | 17篇 |
1989年 | 19篇 |
1988年 | 11篇 |
1987年 | 24篇 |
1986年 | 17篇 |
1985年 | 23篇 |
1984年 | 35篇 |
1983年 | 12篇 |
1982年 | 20篇 |
1981年 | 20篇 |
1980年 | 22篇 |
1979年 | 17篇 |
1978年 | 14篇 |
1977年 | 15篇 |
1975年 | 13篇 |
1974年 | 8篇 |
1973年 | 9篇 |
1972年 | 8篇 |
排序方式: 共有2058条查询结果,搜索用时 15 毫秒
41.
An intrinsic contribution to the spin Hall effect in two‐dimensional silicene is considered theoretically within the linear response theory and Green's function formalism. When an external voltage normal to the silicene plane is applied, the spin Hall conductivity is shown to reveal a transition from the spin Hall insulator phase at low bias to the conventional insulator phase at higher voltages. This transition resembles the recently reported phase transition in bilayer graphene. The spin–orbit interaction responsible for this transition in silicene is much stronger than in graphene, which should make the transition observable experimentally. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
42.
M. Choraś 《Opto-Electronics Review》2008,16(1):85-96
Geometrical methods of feature extraction from ear images in order to perform human identification are presented. Geometrical
approach is motivated by the actual procedures used by police and forensic experts (so-called ear otoscopy). In their work,
geometrical features of ears such as size, height, width, and shapes of earlobe are useful and valid proofs of identity. The
contribution of the article is development of the new and original methods of geometrical feature extraction from 2D ear images.
Four novel algorithms of ear feature extraction from contour images are described in detail. Moreover, identification results
obtained for each of the methods, based on the distance of feature vectors in the feature space, are presented. 相似文献
43.
In this paper we point out some possible links between different approaches to quantum gravity and theories of the Planck scale physics. In particular, connections between loop quantum gravity, causal dynamical triangulations, Ho?ava–Lifshitz gravity, asymptotic safety scenario, Quantum Graphity, deformations of relativistic symmetries and nonlinear phase space models are discussed. The main focus is on quantum deformations of the Hypersurface Deformations Algebra and Poincaré algebra, nonlinear structure of phase space, the running dimension of spacetime and nontrivial phase diagram of quantum gravity. We present an attempt to arrange the observed relations in the form of a graph, highlighting different aspects of quantum gravity. The analysis is performed in the spirit of a mind map, which represents the architectural approach to the studied theory, being a natural way to describe the properties of a complex system. We hope that the constructed graphs (maps) will turn out to be helpful in uncovering the global picture of quantum gravity as a particular complex system and serve as a useful guide for the researchers. 相似文献
44.
Piotr T. Chruściel Erwann Delay Paul Klinger Andreas Kriegl Peter W. Michor Armin Rainer 《Letters in Mathematical Physics》2018,108(9):2009-2030
We prove existence of large families of solutions of Einstein-complex scalar field equations with a negative cosmological constant, with a stationary or static metric and a time-periodic complex scalar field. 相似文献
45.
46.
D. Brill P. Beckerle C. Bormann E. Schwab Y. Shin H. Ströbele P. Baltes C. Müntz H. Oeschler C. Sturm A. Wagner R. Barth M. Cieslak M. Dȩbowski E. Grosse P. Koczoń M. Mang D. Miśkowiec R. Schicker P. Senger B. Kohlmeyer F. Pühlhofer J. Speer K. Völkel W. Waluś 《Zeitschrift für Physik A Hadrons and Nuclei》1997,357(2):207-213
Triple differential cross-sections of midrapidity pions from 209Bi+209Bi collisions were measured with the Kaon Spectrometer at SIS at incident energies of 400, 700 and 1000 AMeV. The azimuthal emission pattern of the pions has been investigated in dependence of beam energy and impact parameter. An enhanced emission of pions perpendicular to the reaction plane is observed. The strength of the anisotropy increases with beam energy and pion transverse momentum. In contrast to the nucleons the anisotropy varies only little with the impact parameter. No difference in the behaviour of positive and negative pions is observed. 相似文献
47.
The problem of identification in fuzzy systems described by the use of fuzzy equation is considered. The identification method and its performance index is also presented. The formal procedure of the identification algorithm is illustrated by means of a numerical example. The possibility of using the proposed algorithm for the solution of a control problem is given as well. 相似文献
48.
P. T. Jochym K. Parlinski A. M. Oleś 《The European Physical Journal B - Condensed Matter and Complex Systems》2008,61(2):173-179
The magnetization distribution, its energetic characterization by the
interlayer coupling constants and lattice dynamics of (001)-oriented
Fe/Pt multilayers are investigated using density functional theory
combined with the direct method to determine phonon frequencies.
It is found that ferromagnetic order between consecutive Fe layers is
favoured, with the enhanced magnetic moments at the
interface. The bilinear and biquadratic coupling coefficients between Fe
layers are shown to saturate fast with increasing thickness of
nonmagnetic Pt layers which separate them. The phonon calculations
demonstrate a rather strong dependence of partial iron phonon
densities of states on the actual position of Fe monolayer
in the multilayer structure. 相似文献
49.
P. Borys Z. J. Grzywna J. Łuczka 《The European Physical Journal B - Condensed Matter and Complex Systems》2011,83(2):223-233
We consider a deterministic process described by a discrete one-dimensional chaotic map and study its diffusive-like properties. Starting with the corresponding Frobenius-Perron equation we derive an approximate evolution equation for the probability distribution which is a partial differential equation of a hyperbolic type. Consequently, the process is correlated, non-Markovian, non-Gaussian and the information propagates with a finite velocity. This is in clear contrast to conventional diffusion processes described by a standard parabolic diffusion equation with an infinite velocity of information propagation. Our approach allows for a more complete characterisation of diffusion dynamics of deterministic systems. 相似文献
50.
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