全文获取类型
收费全文 | 23548篇 |
免费 | 1057篇 |
国内免费 | 792篇 |
专业分类
化学 | 13668篇 |
晶体学 | 177篇 |
力学 | 1660篇 |
综合类 | 61篇 |
数学 | 3182篇 |
物理学 | 6649篇 |
出版年
2022年 | 296篇 |
2021年 | 334篇 |
2020年 | 433篇 |
2019年 | 503篇 |
2018年 | 531篇 |
2017年 | 491篇 |
2016年 | 734篇 |
2015年 | 452篇 |
2014年 | 681篇 |
2013年 | 887篇 |
2012年 | 936篇 |
2011年 | 941篇 |
2010年 | 844篇 |
2009年 | 855篇 |
2008年 | 868篇 |
2007年 | 853篇 |
2006年 | 715篇 |
2005年 | 626篇 |
2004年 | 554篇 |
2003年 | 574篇 |
2002年 | 670篇 |
2001年 | 605篇 |
2000年 | 423篇 |
1999年 | 364篇 |
1998年 | 301篇 |
1997年 | 290篇 |
1996年 | 291篇 |
1995年 | 253篇 |
1993年 | 268篇 |
1992年 | 259篇 |
1991年 | 286篇 |
1990年 | 301篇 |
1989年 | 288篇 |
1985年 | 291篇 |
1984年 | 289篇 |
1983年 | 264篇 |
1982年 | 276篇 |
1980年 | 257篇 |
1979年 | 300篇 |
1978年 | 329篇 |
1977年 | 320篇 |
1976年 | 404篇 |
1975年 | 359篇 |
1974年 | 388篇 |
1973年 | 396篇 |
1972年 | 369篇 |
1971年 | 331篇 |
1970年 | 315篇 |
1969年 | 298篇 |
1968年 | 253篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
11.
12.
M. Ya. Amusia N. A. Cherepkov L. V. Chernysheva 《Journal of Experimental and Theoretical Physics》2003,97(1):34-41
The results of calculations of the elastic scattering cross section of positrons on noble gas and alkali atoms are presented. The calculations are performed within the one-electron Hartree-Fock approximation with multielectron correlations in the so-called random phase approximation with exchange taken into account. Virtual positronium formation is taken into account and proved to be very important. Arguments are presented that the positron polarization potential is repulsive for alkali atoms. The results obtained are in a reasonable agreement with experiment and with some previously reported calculations. 相似文献
13.
C. Czeranowsky V. M. Baev G. Huber P. A. Khandokhin Ya. I. Khanin I. V. Koryukin E. Yu. Shirokov 《Radiophysics and Quantum Electronics》2004,47(10-11):723-728
Experimental study of low-frequency dynamics of an intracavity frequency-doubled Nd:YAG laser demonstrates the influence of the interaction of orthogonally polarized modes, participating in frequency doubling (type II phase matching), on the stability of the laser output. At a sufficiently low pump rate and low conversion efficiency, the laser shows stable operation with a low noise level at the frequencies of relaxation oscillations. At a high pump power and/or a high conversion efficiency, the laser emission becomes unstable as a result of Hopf bifurcation at the frequencies of relaxation oscillations that are responsible for the anti-phase polarization dynamics of the laser. 相似文献
14.
A. Ya. Samuilov L. A. Zenitova I. N. Bakirova Ya. D. Samuilov 《Russian Journal of Applied Chemistry》2008,81(8):1419-1422
Thermodynamic parameters of reactions of methyl and phenyl isocyanates with a series of compounds were determined by quantum-chemical calculations. The products of these reactions model for various functional groups present in commercial polyurethanes. The thermodynamic stability series for compounds formed from aliphatic and aromatic isocyanates were constructed. 相似文献
15.
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
16.
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
17.
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
18.
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
19.
20.
M. Ya. Izrailovich 《Acoustical Physics》2004,50(2):163-168
On the basis of the method of equivalent linearization combined with the method of moments, laws of self-oscillation excitation are obtained that provide the modes with maximum intensity of resonance (or quasi-resonance) oscillations in one-dimensional systems with distributed parameters. A restriction of a general type is imposed on the law of excitation. In the particular case of an integral quadratic restriction, the law of excitation leads to the generation of purely harmonic self-oscillations. The use of an extended (multiplicatively stabilizing) control provides the uniqueness and stability of the quasi-optimal mode of self-oscillation. 相似文献