全文获取类型
收费全文 | 811066篇 |
免费 | 7076篇 |
国内免费 | 2408篇 |
专业分类
化学 | 414228篇 |
晶体学 | 12085篇 |
力学 | 40373篇 |
综合类 | 26篇 |
数学 | 108407篇 |
物理学 | 245431篇 |
出版年
2020年 | 7328篇 |
2019年 | 8257篇 |
2018年 | 10910篇 |
2017年 | 10936篇 |
2016年 | 15669篇 |
2015年 | 9019篇 |
2014年 | 14699篇 |
2013年 | 35819篇 |
2012年 | 27098篇 |
2011年 | 32487篇 |
2010年 | 23591篇 |
2009年 | 23488篇 |
2008年 | 30344篇 |
2007年 | 30371篇 |
2006年 | 28076篇 |
2005年 | 25166篇 |
2004年 | 23272篇 |
2003年 | 20911篇 |
2002年 | 20826篇 |
2001年 | 22157篇 |
2000年 | 17336篇 |
1999年 | 13611篇 |
1998年 | 11747篇 |
1997年 | 11575篇 |
1996年 | 11019篇 |
1995年 | 9990篇 |
1994年 | 10056篇 |
1993年 | 9700篇 |
1992年 | 10357篇 |
1991年 | 10771篇 |
1990年 | 10326篇 |
1989年 | 10064篇 |
1988年 | 10006篇 |
1987年 | 9775篇 |
1986年 | 9268篇 |
1985年 | 12286篇 |
1984年 | 12848篇 |
1983年 | 10738篇 |
1982年 | 11174篇 |
1981年 | 10773篇 |
1980年 | 10374篇 |
1979年 | 10806篇 |
1978年 | 11314篇 |
1977年 | 11114篇 |
1976年 | 11188篇 |
1975年 | 10509篇 |
1974年 | 10447篇 |
1973年 | 10753篇 |
1972年 | 7747篇 |
1971年 | 6626篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
The changes in the magnetization of yttrium iron garnet (YIG) when irradiated by a pulsed neodymium laser beam with wavelength
λ=1.06 μm are investigated. Measurements are performed in the temperature range from 100 K to 600 K in various external magnetic
fields. YIG single crystals grown along the crystallographic (100), (110), and (111) directions are chosen so that the external
anisotropy of the indicated processes can be determined. Characteristic temperature intervals dominated by different mechanisms
of variation of the magnetization under the influence of a laser pulse are discussed.
Fiz. Tverd. Tela (St. Petersburg) 39, 1263–1266 (July 1997) 相似文献
12.
L. K. Aminov I. N. Kurkin D. A. Lukoyanov K. P. Chernov 《Physics of the Solid State》1997,39(8):1184-1186
Results are reported for measurements of the spin-lattice relaxation times of E′1 centers in quartz glass, produced by neutron irradiation, with the measurements made at two frequencies 9.25 and 24.0 GHz
over a wide temperature interval 1.5–300 K. The experimental data are interpreted on the basis of interaction mechanisms of
the spins with two-level systems with excitation energies ∼6, ∼26, and ∼420 cm−1. A small modification of the existing theory allows us to explain a number of features of the observed temperature and frequency
dependence of the relaxation rate. The results are compared with the data available in the literature on spin-lattice relaxation
of irradiation centers in crystalline quartz and quartz glass.
Fiz. Tverd. Tela (St. Petersburg) 39, 1335–1337 (August 1997) 相似文献
13.
V. A. Krakovskii 《Russian Physics Journal》1997,40(1):6-12
The problem of exciting bulk elastic waves at the surface of a piezoelectric with symmetries 422,622 has been solved by a
successive approximation method. In the approximation of a fixed electric field, created at the surface of the piezoelectric
crystal by a two-electrode transducer, the distributions are found for the shear wave stress and the energy flux density in
the far zone. The equivalent circuit parameters for a two-electrode radiator are determined taking account of the dynamic
piezoelectric correction obtained in the second approximation. The equivalent circuit parameters and the transducer loss are
treated for TeO2 crystals. A realistic possibility of using surface transducers in the development of acousto-optic modulators in the s.h.f.
region is shown.
Tomsk State Academy of Control Systems and Radio Electronics. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika,
No. 1, pp. 8–15, January, 1997. 相似文献
14.
15.
J. E. Fischer E. Werwa P. A. Heiney 《Applied Physics A: Materials Science & Processing》1993,56(3):193-196
We have used both reflection-geometry and grazing-incidence-geometry X-ray scattering to study thin films of C60 evaporated onto mica substrates via a hot-wall technique. The growth mode yields close-packed C60 planes, which are parallel to the substrate surface and which exhibit out-of-plane correlation lengths of 850 Å. In the film plane the C60 is at best pseudo-epitaxial, with a 0.9° distribution of crystallite orientations, a 450 Å in-plane correlation length, and a 3.7% lattice mismatch, better than obtained by other thin film techniques but far from the accepted definition of single crystal thin film epitaxy. 相似文献
16.
The Al2O3−CdSe interface of a thin-film transistor is investigated in the frequency range 30 Hz-30 kHz under weak depletion and accumulation.
The surface states are, most likely, located in the insulator Al2O3 with a concentration varying from 4·1018 to 1019 cm−3 eV−1. The surface states have a negligible influence on the thin-film transistor operation. 相似文献
17.
The problem of the vector and axial-vector dominance of weak interactions within the framework of the quark model of superconductivity type is discussed. 相似文献
18.
19.
A. Sebbar 《Mathematische Zeitschrift》1989,201(4):561-581
Sans résumé 相似文献
20.
L. A. Khalfin 《Journal of Mathematical Sciences》1987,36(5):616-626
The article surveys the main results of the statistical approach to the solution of ill-posed problems of mathematical physics, in application to specific ill-posed inverse problems in geophysics.Invited paper presented at the International Seminar on Mathematical Foundations of the Interpretation of Geophysical Fields, Moscow, May–June 1972.Translated from Zapiski Nauchnykh Seminarov Leningradskogo Otdeleniya Matematicheskogo Instituta im. V. A. Steklova AN SSSR, Vol. 79, pp. 67–81, 1978. 相似文献