全文获取类型
收费全文 | 44743篇 |
免费 | 761篇 |
国内免费 | 552篇 |
专业分类
化学 | 21919篇 |
晶体学 | 560篇 |
力学 | 2453篇 |
综合类 | 40篇 |
数学 | 6467篇 |
物理学 | 14617篇 |
出版年
2022年 | 351篇 |
2021年 | 617篇 |
2020年 | 704篇 |
2019年 | 934篇 |
2018年 | 1408篇 |
2017年 | 1484篇 |
2016年 | 1855篇 |
2015年 | 906篇 |
2014年 | 1600篇 |
2013年 | 2410篇 |
2012年 | 2239篇 |
2011年 | 2331篇 |
2010年 | 2435篇 |
2009年 | 2352篇 |
2008年 | 2378篇 |
2007年 | 2318篇 |
2006年 | 1952篇 |
2005年 | 1386篇 |
2004年 | 1057篇 |
2003年 | 866篇 |
2002年 | 863篇 |
2001年 | 828篇 |
2000年 | 973篇 |
1999年 | 644篇 |
1998年 | 704篇 |
1997年 | 670篇 |
1996年 | 365篇 |
1995年 | 269篇 |
1993年 | 275篇 |
1992年 | 273篇 |
1991年 | 278篇 |
1990年 | 289篇 |
1989年 | 291篇 |
1985年 | 284篇 |
1984年 | 297篇 |
1983年 | 268篇 |
1982年 | 283篇 |
1980年 | 260篇 |
1979年 | 303篇 |
1978年 | 332篇 |
1977年 | 327篇 |
1976年 | 404篇 |
1975年 | 363篇 |
1974年 | 392篇 |
1973年 | 399篇 |
1972年 | 370篇 |
1971年 | 334篇 |
1970年 | 315篇 |
1969年 | 298篇 |
1968年 | 263篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
This Note addresses the derivation of an improved On-Surface Radiation Condition for the numerical solution of the exterior Helmholtz equation at high-frequencies. This condition is built as an approximation of the Neumann-to-Dirichlet map by using a local regularization of its principal classical symbol in the gliding zone for modelling the creeping waves. The numerical simulation of this pseudodifferential operator is efficiently realized with a linear cost according to the dimension of the boundary element approximation space using suitable complex Padé approximants. A numerical example is provided. To cite this article: X. Antoine et al., C. R. Acad. Sci. Paris, Ser. I 340 (2005). 相似文献
102.
M. P. Nosov V. A. Smirnova Yu. F. Zabashta A. Ya. Fridman M. P. Mokhnach 《Mechanics of Composite Materials》1989,25(1):8-12
Conclusion A method was proposed which makes it possible to study the low-frequency internal friction of complex fibers. This method was used to study the internal friction of complex composite fibers based on PCA and PE. We observed a relaxation process which is typical of the composite and is absent in the pure materials.Translated from Mekhanika Kompozitnykh Materialov, No. 1, pp. 11–15, January–February, 1989. 相似文献
103.
P. P. Kirpichok N. B. Voronina A. F. Sitnikov V. Ya. Garmash 《Russian Physics Journal》1989,32(1):26-30
The effect of rare-earth oxides on the properties of anisotropic barium ferrites has been studied by x-ray structural and Mössbauer methods. Additions of SrCO3, as well as SrCO3 and La2O3, SrCO3 and Pr6O11, SrCO3 and Nd2O3, SrCO3 and Sm2O3 in amounts of 7.5 mole % Sr and 10 mole % rare-earth element to grade-A barium powder results in the substitution of barium ions by Sr and rare-earth ions; consequently, the energy of magnetic anisotropy changes and the technically important parameters Br and (BH)max increase.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 1, pp. 34–39, January, 1989. 相似文献
104.
The method of nonlinear moments, when used to solve the Boltzmann equation, necessitates the calculation of collision integral
matrix elements. The matrix elements are hard to calculate numerically, especially at large indices. The asymptotics of the
matrix elements are constructed. In terms of the model of pseudopower particle interaction, a formula free of summation is
derived. This makes it possible to find the asymptotic behavior of linear and nonlinear elements when two indices are large.
For an arbitrary interaction cross section, asymptotic expansions of linear and nonlinear matrix elements in one index are
obtained. For Maxwellian molecules, asymptotic formulas are derived for three large indices. 相似文献
105.
The goal of the paper is to analyse properties of solutions for linear thermoelastic systems of type III in one space variable. Our approach does not use energy methods, it bases on a special diagonalization procedure which is different in different parts of the phase space. This procedure allows to derive explicit representations of solutions. These representations help to prove results for well‐posedness of the Cauchy problem, LP–Lq decay estimates on the conjugate line and results for propagation of singularities. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
106.
B. Ya. Balagurov 《Technical Physics》2003,48(8):945-951
A sequential scheme for calculating the polarizability of a pair of parallel cylinders with an arbitrary (but fairly symmetric) form is suggested. An infinite set of algebraic equations is derived for coefficients involved in an expression for the potential. The numerical solution of this set makes it possible to find the polarizability with any degree of accuracy. This method is unrelated to the cylinder shape. The electrostatic properties of the cylinders are described in terms of the multipolar polarizability matrix. 相似文献
107.
Olga V. Man’ko 《Acta Physica Hungarica A》2004,19(3-4):313-316
A short review of the general principles of constructing tomograms of spin and quark states is presented. 相似文献
108.
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
109.
V. V. Dvorkin N. N. Dzbanovskii A. F. Pal’ N. V. Suetin A. Yu. Yur’ev P. Ya. Detkov 《Physics of the Solid State》2004,46(4):729-732
A suspension of ultrafine-dispersed nanodiamond was used for introducing (in particular, selectively) high-density centers of diamond nucleation on various substrates. High-quality doped diamond films to be used as electrochemistry electrodes were deposited from the gas phase in a microwave discharge on certain substrates treated using ultrafine-dispersed nanodiamond. A uniform distribution of nucleation centers with concentrations greater than 1010 cm-2 on silicon substrates was obtained. Electrochemical current-potential curves were measured for continuous films. Diamond meshes of different transparency were grown using selective nucleation. Successful production of high-quality doped diamond meshes gives grounds to consider them the most promising electrodes for use in electrochemistry. 相似文献
110.
In terms of two-dimensional dislocation-disclination dynamics, a theoretical model is developed to describe the decay of a low-angle tilt boundary in a deformed nanocrystalline material under the action of an externally applied elastic stress and of the elastic field of a neighboring decayed boundary. The critical external stresses are calculated at which the boundary decays and the dislocations making up this boundary either are trapped by the boundary that decayed earlier or break away from both boundaries. The decay of a low-angle tilt boundary is shown to result in a substantial decrease in the critical decay stresses for the neighboring boundaries, which can cause an avalanche-like chain decay of low-angle boundaries yielding high-density ensembles of mobile dislocations capable of carrying substantial plastic deformations and of forming shear bands in deformed nanocrystalline materials. 相似文献