全文获取类型
收费全文 | 26750篇 |
免费 | 160篇 |
国内免费 | 40篇 |
专业分类
化学 | 12367篇 |
晶体学 | 419篇 |
力学 | 963篇 |
综合类 | 11篇 |
数学 | 3734篇 |
物理学 | 9456篇 |
出版年
2023年 | 35篇 |
2022年 | 209篇 |
2021年 | 510篇 |
2020年 | 465篇 |
2019年 | 642篇 |
2018年 | 1091篇 |
2017年 | 1190篇 |
2016年 | 1431篇 |
2015年 | 607篇 |
2014年 | 1187篇 |
2013年 | 1822篇 |
2012年 | 1677篇 |
2011年 | 1795篇 |
2010年 | 1878篇 |
2009年 | 1815篇 |
2008年 | 1835篇 |
2007年 | 1808篇 |
2006年 | 1575篇 |
2005年 | 1019篇 |
2004年 | 729篇 |
2003年 | 418篇 |
2002年 | 410篇 |
2001年 | 348篇 |
2000年 | 635篇 |
1999年 | 366篇 |
1998年 | 466篇 |
1997年 | 447篇 |
1996年 | 128篇 |
1995年 | 42篇 |
1994年 | 39篇 |
1993年 | 16篇 |
1992年 | 19篇 |
1991年 | 17篇 |
1990年 | 18篇 |
1989年 | 8篇 |
1988年 | 11篇 |
1987年 | 15篇 |
1986年 | 12篇 |
1985年 | 19篇 |
1984年 | 8篇 |
1983年 | 11篇 |
1982年 | 8篇 |
1981年 | 16篇 |
1980年 | 20篇 |
1979年 | 11篇 |
1978年 | 7篇 |
1977年 | 8篇 |
1976年 | 7篇 |
1969年 | 8篇 |
1968年 | 15篇 |
排序方式: 共有10000条查询结果,搜索用时 265 毫秒
81.
E. A. Ekimov E. L. Gromnitskaya D. A. Mazalov A. F. Pal’ V. V. Pichugin S. Gierlotka B. Palosz J. A. Kozubowski 《Physics of the Solid State》2004,46(4):755-757
Superhard nanodiamond-SiC ceramics are prepared by infiltrating liquid Si into porous nanodiamond compacts under pressure.
Synthesized samples are 2.2 mm thick and 3–4 mm in diameter. The effect of particle size of dynamically synthesized nanodiamond
powders on silicon infiltration and SiC phase formation is studied. It is established that silicon does not penetrate into
the pores of nanodiamond powders if the original particle size is smaller than 0.5–1.0 μm. The critical pore size for infiltration
is 100–200 nm. A study of the microstructure of the samples showed the presence of the nanometer-and submicron-scale SiC phase.
The ultrasound velocities are measured in the prepared compacts, and the elastic moduli are calculated.
__________
Translated from Fizika Tverdogo Tela, Vol. 46, No. 4, 2004, pp. 734–736.
Original Russian Text Copyright ? 2004 by Ekimov, Gromnitskaya, Mazalov, Pal’, Pichugin, Gierlotka, Palosz, Kozubowski. 相似文献
82.
Growth of thin Ti films on (100)W and the kinetics of their oxidation are studied using thermal-desorption spectroscopy and Auger electron spectroscopy. Titanium films grow nearly layer by layer on the (100)W face at room temperature. The activation energy for desorption of Ti atoms decreases from 5.2 eV for coverage θ=0.1 to 4.9 eV in a multilayer film. Oxidation of a thin (θ=6) titanium film starts with dissolution of oxygen atoms in its bulk to the limiting concentration for a given temperature, after which the film oxidizes to TiO, with the TiO2 oxide starting to grow when exposure of the film to oxygen is prolonged. The thermal desorption of oxides follows zero-order kinetics and is characterized by desorption activation energies of 5.1 (TiO) and 5.9 eV (TiO2). 相似文献
83.
Technical Physics - An analytical expression for the generatrix of the shape of a nonlinearly vibrating charged drop of a perfect incompressible conducting fluid immersed in an ideal incompressible... 相似文献
84.
E. V. Aksenova A. Yu. Val’kov A. A. Karetnikov A. P. Kovshik V. P. Romanov E. I. Ryumtsev 《Journal of Experimental and Theoretical Physics》2004,99(5):965-977
The phenomenon of extraordinary ray refraction in a helical liquid crystal with large (compared to the light wavelength) pitch has been studied by theoretical and experimental methods. At a sufficiently large angle of incidence relative to the pitch axis, the extraordinary ray exhibits reflection (reversal) from a certain layer of the medium. The ordinary ray, for which the system is optically isotropic, exhibits no such reflection. The experimental dependences of the transmitted and reflected (reversed) rays are described using the geometrical optics approximation taking into account the optical losses for scattering inside the liquid crystal. 相似文献
85.
L. M. Vasilyak M. N. Vasil’ev S. P. Vetchinin D. N. Polyakov V. E. Fortov 《Journal of Experimental and Theoretical Physics》2003,96(3):440-443
The action of an electron beam on ordered dust structures in glow and low-pressure RF discharges was studied experimentally. The electron beam produces destruction and dynamic displacement of the dust structure. In the center of a dust structure, an electron beam with a low electron energy (tens of eV) at currents up to 1 mA caused structural disordering and “melting” in the region of its action but did not excite external crystal regions. Local action of an electron beam with a high electron energy (25 keV) and a beam current above 10 mA caused deformation of the whole dust structure and shifted it in the horizontal direction so that it was carried away from the RF discharge zone. The effect of dust structure displacements can be used to locally remove particles from a plasma. 相似文献
86.
The acoustoelectromagnetic interaction is examined in a regime where three mechanisms must be taken into account simultaneously:
photoelasticity, quadratic photoelasticity, and elastic nonlinearity. It is shown that beyond the critical conditions, acoustic
solitary waves are formed at harmonic and subharmonic frequencies in a crystal. Including damping and nonideal reflection
at the boundaries does not lead to the establishment of any sort of stationary state: a soliton spatial-temporal dynamic develops.
Fiz. Tverd. Tela (St. Petersburg) 39, 1101–1104 (June 1997) 相似文献
87.
Andrei Finkelstein Olga Kosheleva Vladik Kreinovich 《International Journal of Theoretical Physics》1997,36(4):1009-1020
Inimage processing (e.g., inastronomy), the desired black-and-white image is, from the mathematical viewpoint, aset. Hence, to process images, we need to process sets. To define a generic set, we need infinitely many parameters; therefore,
if we want to represent and process sets in the computer, we must restrict ourselves to finite-parameter families of sets
that will be used to approximate the desired sets. The wrong choice of a family can lead to longer computations and worse
approximation. Hence, it is desirable to find the family that it isthe best in some reasonable sense. In this paper, we show how the problems of choosing the optimal family of sets can be formalized
and solved. As a result of the described general methodology, forastronomical images, we get exactly the geometric shapes that have been empirically used by astronomers and astrophysicists; thus, we have atheoretical explanation for these shapes. 相似文献
88.
We consider the application of asymptotic methods of nonlinear mechanics (the Krylov-Bogolyubov-Mitropol'skii method) and
the method of separation of motions in nonlinear systems for the construction of an approximate solution of a nonlinear equation
that describes a nonstationary wave process.
Translated from Ukrainskii Matematicheskii Zhurnal, Vol. 50, No. 3, pp. 357–371, March, 1998. 相似文献
89.
Yu. A. Mitropol’skii Nguyen Dong Anh Nguyen Dyk Tynh 《Ukrainian Mathematical Journal》1998,50(11):1731-1737
We construct the second approximation for random oscillations described by the Van der Pol equation which are under the action
of a broadband random process.
Translated from Ukrainskii Matematicheskii Zhurnal, Vol. 50, No. 11, pp. 1517–1521, November, 1998. 相似文献
90.
An expression for the probability of thermally activated tunneling ionization in an electric field in the presence of a magnetic
field is obtained. It is shown that the logarithm of the ionization probability is proportional to the squared electric field,
and the coefficient of proportionality decreases with increasing magnetic field.
Pis’ma Zh. éksp. Teor. Fiz. 68, No. 10, 763–767 (25 November 1998) 相似文献