全文获取类型
收费全文 | 387922篇 |
免费 | 3217篇 |
国内免费 | 962篇 |
专业分类
化学 | 207600篇 |
晶体学 | 5693篇 |
力学 | 17544篇 |
综合类 | 15篇 |
数学 | 43130篇 |
物理学 | 118119篇 |
出版年
2019年 | 3245篇 |
2018年 | 4273篇 |
2017年 | 4249篇 |
2016年 | 6482篇 |
2015年 | 3912篇 |
2014年 | 6246篇 |
2013年 | 15968篇 |
2012年 | 11976篇 |
2011年 | 14836篇 |
2010年 | 10481篇 |
2009年 | 10284篇 |
2008年 | 13788篇 |
2007年 | 14037篇 |
2006年 | 13164篇 |
2005年 | 11948篇 |
2004年 | 10785篇 |
2003年 | 9732篇 |
2002年 | 9693篇 |
2001年 | 10623篇 |
2000年 | 8258篇 |
1999年 | 6391篇 |
1998年 | 5577篇 |
1997年 | 5535篇 |
1996年 | 5160篇 |
1995年 | 4799篇 |
1994年 | 4929篇 |
1993年 | 4525篇 |
1992年 | 5204篇 |
1991年 | 5285篇 |
1990年 | 5063篇 |
1989年 | 4958篇 |
1988年 | 4985篇 |
1987年 | 4816篇 |
1986年 | 4578篇 |
1985年 | 6036篇 |
1984年 | 6393篇 |
1983年 | 5335篇 |
1982年 | 5634篇 |
1981年 | 5466篇 |
1980年 | 5380篇 |
1979年 | 5459篇 |
1978年 | 5888篇 |
1977年 | 5708篇 |
1976年 | 5806篇 |
1975年 | 5419篇 |
1974年 | 5520篇 |
1973年 | 5644篇 |
1972年 | 3927篇 |
1971年 | 3371篇 |
1970年 | 3068篇 |
排序方式: 共有10000条查询结果,搜索用时 156 毫秒
31.
E. V. Zakharov A. G. Davydov Yu. V. Pimenov G. M. Tikhonov 《Computational Mathematics and Modeling》1991,2(1):79-84
Translated from Chislennye Metody Resheniya Obratnykh Zadach Matematicheskoi Fiziki, pp. 119–127. 相似文献
32.
We demonstrate a method that permits to obtain generalized solutions for some quasilinear equations and systems of hyperbolic
type. The corresponding variational principle is constructed using the theory of equilibrium of a potential in an external
field.
Dedicated to the memory of B. M. Levitan
Supported by RFBR grants Nos. 05-01-00522 and NSh-1551.2003.1, by Program No. 1 of the Branch of Mathematics, Russian Academy
of Sciences, and by INTAS project No. 03-51-6637. 相似文献
33.
T. Kumita Y. Kamiya M. Babzien I. Ben-Zvi K. Kusche I. V. Pavlishin I. V. Pogorelsky D. P. Siddons V. Yakimenko T. Hirose T. Omori J. Urakawa K. Yokoya D. Cline F. Zhou 《Laser Physics》2006,16(2):267-271
Thomson scattering of high-power laser and electron beams is a good test of electrodynamics in the high-field region. We demonstrated production of high-intensity X-rays in the head-on collision of a CO2 laser and 60-MeV electron beams at Brookhaven National Laboratory, Accelerator Test Facility. The energy of an X-ray photon was limited at 6.5 keV in the linear (lowest order) Thomson scattering, but the nonlinear (higher order) process produces higher energy X-rays. We measured the angular distribution of the high-energy X-rays and confirmed that it agrees with theoretical predictions. 相似文献
34.
35.
Evaluation of the Planck-mean absorption coefficients from HITRAN and HITEMP databases 总被引:1,自引:0,他引:1
Hongmei ZhangMichael F. Modest 《Journal of Quantitative Spectroscopy & Radiative Transfer》2002,73(6):649-653
New values of Planck-mean absorption coefficients are presented for various gases, based on line-by-line calculations from the high-resolution databases, HITRAN and HITEMP. The new values are compared with previously published Planck-mean absorption coefficients. 相似文献
36.
H.S RagabA Shehap M.S Abo EllilW.H Osman F.H Abd El-Kader 《Journal of Physics and Chemistry of Solids》2002,63(10):1839-1847
Ternary-phase ceramic system of Li2O Al2O3 4SiO2 doped with CuO, FeO and TiO2 has been prepared and subjected to dc electrical conductivity and thermally stimulated depolarization current (TSDC) measurements as a function of temperature (30-250 °C) and field strength. The electrical conductivity results are explained by assuming both ionic and electronic conduction mechanisms coexist with different contributions over the whole temperature range of experiments. TSDC spectra have been found to be characterized by a broad intense relaxation peak, which can be attributed to an ionic charge polarization. The broad relaxation transitions are apparently a result of the nonuniform nature of this process. Activation energies are calculated for both dc electrical conductivity and TSDC according to Arrhenius equation and initial rise method, respectively. 相似文献
37.
A noiselike fine structure of ferromagnetic resonance spectra in magnetic powders was investigated after ultrasonic treatment. Magnetic interactions between particles are proved to have an influence upon the fine structure formation. After decreasing dipole-dipole magnetic interactions in dilute suspension a special order appears in fine-structure spectra, which is generally the same for different systems. 相似文献
38.
de Souza P. A. Garg V. K. Klingelhöfer G. Gellert R. Gütlich P. 《Hyperfine Interactions》2002,139(1-4):705-714
A portable Mössbauer spectrometer, developed for extraterrestrial applications, opens up new industrial applications of MBS. But for industrial applications, an available tool for fast data analysis is also required, and it should be easy to handle. The analysis of Mössbauer spectra and their parameters is a barrier for the popularity of this wide-applicable spectroscopic technique in industry. Based on experience, the analysis of a Mössbauer spectrum is time-consuming and requires the dedication of a specialist. However, the analysis of Mössbauer spectra, from the fitting to the identification of the sample phases, can be faster using by genetic algorithms, fuzzy logic and artificial neural networks. Industrial applications are very specific ones and the data analysis can be performed using these algorithms. In combination with an automatic analysis, the Mössbauer spectrometer can be used as a probe instrument which covers the main industrial needs for an on-line monitoring of its products, processes and case studies. Some of these real industrial applications will be discussed. 相似文献
39.
A. I. Magunov A. Ya. Faenov I. Yu. Skobelev T. A. Pikuz E. Biémont P. Quinet F. Blasco C. Bonte F. Dorchies T. Caillaud F. Salin C. Stenz 《Journal of Experimental and Theoretical Physics》2002,95(6):998-1005
The satellite structure of 1s2p 1,3 P 1-1s 21 S 0 lines of the He-like argon ion in plasma produced by a 45-fs laser pulse in a gas-jet cluster target is measured with a high spectral resolution. Radiation transitions 2p → 1s from autoionizing states (AISs) are detected for ions ranging from Li-like to F-like. The spectrum observed is theoretically simulated with the use of the spectroscopic data for the AISs of multicharged ions obtained within the multiconfiguration relativistic Hartree-Fock method. Good agreement with experimental data is obtained when the main population channels of these states are taken into account for typical values of cluster-target plasma parameters. 相似文献
40.
Q. Sun Q. Wang X.G. Gong V. Kumar Y. Kawazoe 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,18(1):77-81
We report results of the atomic and electronic structures of Al7C cluster using ab initio molecular dynamics with ultrasoft pseudopotentials and generalized gradient approximation. The lowest energy structure is
found to be the one in which carbon atom occupies an interstitial position in Al7 cluster. The electronic structure shows that the recent observation [Chem. Phys. Lett. 316, 31 (2000)] of magic behavior of Al7C- cluster is due to a large highest occupied and lowest unoccupied molecular orbital (HOMO-LUMO) gap which makes Al7C- chemically inert. These results have further led us to the finding of a new neutral magic cluster Al7N which has the same number of valence electrons as in Al7C- and a large HOMO-LUMO gap of 1.99 eV. Further, calculations have been carried out on (Al7N)2 to study interaction between magic clusters.
Received 28 July 2001 相似文献