全文获取类型
收费全文 | 5092篇 |
免费 | 57篇 |
国内免费 | 16篇 |
专业分类
化学 | 2298篇 |
晶体学 | 72篇 |
力学 | 144篇 |
数学 | 597篇 |
物理学 | 2054篇 |
出版年
2023年 | 17篇 |
2022年 | 77篇 |
2021年 | 116篇 |
2020年 | 85篇 |
2019年 | 157篇 |
2018年 | 225篇 |
2017年 | 213篇 |
2016年 | 238篇 |
2015年 | 113篇 |
2014年 | 189篇 |
2013年 | 281篇 |
2012年 | 315篇 |
2011年 | 357篇 |
2010年 | 332篇 |
2009年 | 311篇 |
2008年 | 326篇 |
2007年 | 300篇 |
2006年 | 313篇 |
2005年 | 216篇 |
2004年 | 158篇 |
2003年 | 114篇 |
2002年 | 105篇 |
2001年 | 96篇 |
2000年 | 115篇 |
1999年 | 80篇 |
1998年 | 92篇 |
1997年 | 63篇 |
1996年 | 22篇 |
1995年 | 7篇 |
1994年 | 7篇 |
1992年 | 6篇 |
1991年 | 5篇 |
1990年 | 6篇 |
1987年 | 3篇 |
1985年 | 7篇 |
1984年 | 4篇 |
1983年 | 10篇 |
1981年 | 8篇 |
1980年 | 5篇 |
1979年 | 9篇 |
1978年 | 10篇 |
1977年 | 8篇 |
1976年 | 5篇 |
1975年 | 5篇 |
1974年 | 3篇 |
1973年 | 4篇 |
1972年 | 4篇 |
1971年 | 3篇 |
1969年 | 4篇 |
1961年 | 2篇 |
排序方式: 共有5165条查询结果,搜索用时 31 毫秒
81.
Maxim A. Gorlach Mingzhao Song Alexey P. Slobozhanyuk Andrey A. Bogdanov Pavel A. Belov 《固体物理学:研究快报》2016,10(12):900-904
Employing nonlocal homogenization approach, we investigate the properties of a metamaterial consisting of parallel metallic wires with dielectric coating. We demonstrate that manipulation of dielectric contrast between wire dielectric shell and host material at fixed frequency results in dynamic switching of metamaterial dispersion regime from elliptic to the hyperbolic one, i.e. the topological transition takes place. It is proved that such transition can be induced by the variation of the metamaterial temperature. Our findings thus pave a way to the implementation of a tunable ‘elliptic‐hyperbolic’ metamaterial. 相似文献
82.
M. N. Achasov K. I. Beloborodov A. V. Berdyugin A. G. Bogdanchikov D. A. Bukin A. V. Vasil’ev V. B. Golubev T. V. Dimova V. P. Druzhinin I. A. Koop A. A. Korol’ S. V. Koshuba E. V. Pakhtusova S. I. Serednyakov Z. K. Silagadze A. N. Skrinsky Yu. M. Shatunov 《Journal of Experimental and Theoretical Physics》2010,110(1):26-33
We have searched for the process e+e- → K+K-π0 at energies up to 1.38 GeVin an experiment with the spherical neutral detector at the VEPP-2M e+e- collider. The upper limits of the cross sections for the processes σ(e+e →; φπ: → K+K-π0) < 0.023 nb and σ(e+e- → KK*(892) → K+K-π0) < 0.059 nb have been established at a 95% confidence level. 相似文献
83.
M.E. Sasin R.P. Seisyan M.A. Kaliteevski S. Brand R.A. Abram J.M. Chamberlain I.V. Iorsh I.A. Shelykh A.Yu. Egorov A.P. Vasil’ev V.S. Mikhrin A.V. Kavokin 《Superlattices and Microstructures》2010
We report on the first experimental observation of Tamm plasmon-polaritons (TPP) formed at the interface between a metal and a dielectric Bragg reflector (DBR). Contrary to conventional surface plasmons, TPPs have an in-plane wave vector less than the wave vector of light in vacuum, which allows for their direct optical excitation, and can be formed in both the TE and TM polarizations. The angular resolved reflectivity and transmission spectra of a GaAs/AlAs DBR covered by Au films of various thicknesses show the resonances associated with the TPP at low temperatures and at room temperature. The in-plane dispersion of TTPs is parabolic with an effective mass 4×10−5 of the free electron mass. 相似文献
84.
For the three-dimensional incompressible Navier–Stokes equations, we present a formulation featuring velocity, vorticity and helical density as independent variables. We find the helical density can be observed as a Lagrange multiplier corresponding to the divergence-free constraint on the vorticity variable, similar to the pressure in the case of the incompressibility condition for velocity. As one possible practical application of this new formulation, we consider a time-splitting numerical scheme based on an alternating procedure between vorticity–helical density and velocity–Bernoulli pressure systems of equations. Results of numerical experiments include a comparison with some well-known schemes based on pressure–velocity formulation and illustrate the competitiveness on the new scheme as well as the soundness of the new formulation. 相似文献
85.
S.?G.?Barsov S.?I.?Vorob’ev E.?I.?Golovenchits A.?A.?Dzyuba E.?N.?Komarov V.?P.?Koptev S.?A.?Kotov V.?A.?Sanina G.?V.?Shcherbakov 《Bulletin of the Russian Academy of Sciences: Physics》2010,74(5):705-707
The present paper is devoted to studying the multiferroics HoMnO3, YMnO3, EuMn2O5, and GdMn2O5 by means of the µSR-method. Determination of the dynamic relaxation parameter 7n and the distribution of the local magnetic fields results in a clear phase diagram. 相似文献
86.
E. A. Vasil’ev E. M. Gushchin N. A. Mikhanchuk I. M. Obodovskii S. G. Pokachalov 《Russian Journal of Physical Chemistry B, Focus on Physics》2010,4(4):671-675
The rates of free thermal electron capture were measured depending on the buffer gas (CO2) pressure for 15 organic compounds in an ionization chamber with laser cathode photoionization. Procedures for preparing
the tested gas mixtures and experimental data processing are described. 相似文献
87.
L. B. Zuev V. I. Danilov S. V. Konovalov R. A. Filip’ev V. E. Gromov 《Physics of the Solid State》2009,51(6):1137-1141
The effect of the electric potential on the microhardness of aluminum, zirconium, and ferrosilicon was studied experimentally. The effect of the proper electric potential applied to a sample is compared with the effect of the potential induced by the contact potential difference upon contact with metals with a different electron work function. These two types of electrical action are revealed to be qualitatively equivalent to each other. It is established that these effects can markedly (up to 15%) change the microhardness of the metals. 相似文献
88.
V. F. Agekyan N. N. Vasil’ev A. Yu. Serov N. G. Filosofov G. Karczewski 《Physics of the Solid State》2004,46(9):1776-1780
Emission spectra of three Cd0.6Mn0.4Te/Cd0.5Mg0.5Te superlattices with Cd0.6Mn0.4Te quantum-well (QW) widths of 7, 13, and 26 monolayers, respectively, and the same thickness (46 monolayers) of the Cd0.5Mg0.5Te barriers have been studied. The QW width affects the shape and spectral position of the Mn2+ intracenter luminescence (IL) band as a result of the crystal field being dependent on the position of the manganese ion with respect to the interface. Measured in identical experimental conditions, the exciton luminescence as compared to the IL is substantially higher in intensity in a QW than in a bulk CdMnTe crystal. Some samples of superlattices and bulk crystals exhibit, in addition to the conventional IL band near 2.0 eV, a weaker band at about 1.45 eV. This band apparently derives from intracenter transitions in the Mn2+ ions in the regions where the crystal lattice has the rock-salt rather than the conventional zinc blende structure. 相似文献
89.
A scheme of nuclear excitation by the ionic X-ray lines in laser plasma using two femtosecond laser pulses is proposed. The first pulse produces plasma with a given degree of ionization, allowing the X-ray line energies of the target ions to be tuned to resonance with the nuclear transition, while the second pulse generates hot electrons that are necessary for X-ray generation. 相似文献
90.
Excepted for the very short terms the frequency stability of ultra-stable oscillators is mainly limited by the resonator noise. In this work we proposed a parametric model of the bulk acoustic wave (BAW) resonator phase noise based on an equivalent circuit. This model explains phase noise generated by a BAW crystal from a point of view of parametric fluctuations and proves the f−1 dependences of the crystal noise. The model performance is verified with simulation. Simulation results are compared to experimental data and discussed. Comparison of three existing models is made. 相似文献