全文获取类型
收费全文 | 529965篇 |
免费 | 4227篇 |
国内免费 | 1294篇 |
专业分类
化学 | 269971篇 |
晶体学 | 7653篇 |
力学 | 26019篇 |
综合类 | 17篇 |
数学 | 67924篇 |
物理学 | 163902篇 |
出版年
2021年 | 5063篇 |
2020年 | 5500篇 |
2019年 | 6249篇 |
2018年 | 8431篇 |
2017年 | 8578篇 |
2016年 | 11667篇 |
2015年 | 6223篇 |
2014年 | 10487篇 |
2013年 | 23567篇 |
2012年 | 18414篇 |
2011年 | 21887篇 |
2010年 | 16480篇 |
2009年 | 16328篇 |
2008年 | 20737篇 |
2007年 | 20574篇 |
2006年 | 18669篇 |
2005年 | 16669篇 |
2004年 | 15517篇 |
2003年 | 13989篇 |
2002年 | 13893篇 |
2001年 | 14750篇 |
2000年 | 11387篇 |
1999年 | 8772篇 |
1998年 | 7615篇 |
1997年 | 7488篇 |
1996年 | 6943篇 |
1995年 | 6275篇 |
1994年 | 6284篇 |
1993年 | 6039篇 |
1992年 | 6397篇 |
1991年 | 6894篇 |
1990年 | 6595篇 |
1989年 | 6491篇 |
1988年 | 6338篇 |
1987年 | 6144篇 |
1986年 | 5880篇 |
1985年 | 7423篇 |
1984年 | 7786篇 |
1983年 | 6541篇 |
1982年 | 6827篇 |
1981年 | 6338篇 |
1980年 | 6008篇 |
1979年 | 6510篇 |
1978年 | 6747篇 |
1977年 | 6634篇 |
1976年 | 6591篇 |
1975年 | 6307篇 |
1974年 | 6133篇 |
1973年 | 6428篇 |
1972年 | 4706篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
301.
302.
M. U. Belyi N. E. Bartnitskaya I. F. Mel'nik B. A. Okhrimenko S. M. Yablochkov 《Journal of Applied Spectroscopy》1995,62(3):564-567
T. Shevchenko Kiev University, 252022 Kiev, Pr. Akad. Glushakova, 6, Ukraine. Translated from Zhurnal Prikladnoi Spektroskopii,
Vol. 62, No. 3, pp. 192–196, May–June, 1995. 相似文献
303.
This paper provides a rigorous proof of the existence of an infinite number of black hole solutions to the Einstein-Yang/Mills equations with gauge groupSU(2), for any event horizon. It is also demonstrated that the ADM mass of each solutions is finite, and that the corresponding Einstein metric tends to the associated Schwarzschild metric at a rate 1/r
2, asr tends to infinity.Research supported in part by the NSF, Contract No. DMS-89-05205Research supported in part by the DE, Contract No. De-FG 02-88 EF 25065 相似文献
304.
305.
F. A. Rustamov 《Optical and Quantum Electronics》1995,27(2):117-125
Based on a previously developed two-level model of four-wave interaction in photorefractive crystals, expressions for the amplitude and phase of a transmission holographic grating have been obtained. The analysis of these expressions points to the dependence of both the amplitude and the phase of the grating on the intensity of the readout beam. 相似文献
306.
F. Rubio F. García H. D. Burrows A. A. C. C. Pais A. J. M. Valente M. J. Tapia J. M. García 《Journal of polymer science. Part A, Polymer chemistry》2007,45(9):1788-1799
The interaction between trivalent lanthanide ions and poly(1,4,7,10,13‐pentaoxacyclopentadecan‐2‐yl‐methyl methacrylate), PCR5, in aqueous solution and in the solid state have been studied. In aqueous solution, evidence of a weak interaction between the lanthanides and PCR5 comes from the small red shift of the Ce(III) emission spectra and the slight broadening of the Gd(III) EPR spectra. From the Tb(III) lifetimes in the presence of H2O and D2O the loss of one or two water coordinated molecules is confirmed when Tb(III) is bound to PCR5. An association constant of the order of 200 M?1 was obtained for a 1:1 (lanthanide:15‐crown‐5) complex from the shift of the polymer NMR signals induced by Tb(III). A similar association constant is obtained from the differences of the molar conductivity of Ce(III) solution at various concentrations in presence and absence of PCR5. When Tb(III) is adsorbed on PCR5 membranes, lifetime experiments in H2O and D2O confirm the loss of 5 or 6 water coordinated molecules indicating that in solid state the lanthanide(III)‐PCR5 interaction is stronger than in solution. The adsorption of Ce(III) in PCR5 membranes shows a Langmuir type isotherm, from which an equilibrium constant of 39 M?1 has been calculated. SEM shows that the membrane morphology is not much affected by lanthanide adsorption. Support for lanthanide ion–crown interactions comes from ab initio calculations on 15‐crown‐5/La(III) complex. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 1788–1799, 2007 相似文献
307.
Magnetic-structure distortions induced by an external magnetic field near a rough surface of a uniaxial collinear antiferromagnet are analyzed using mathematical modeling. The “magnetic field-roughness” phase diagram of these distortions is constructed. It is demonstrated that, under specific conditions, the presence of atomic steps leads to the formation of domains in the surface layer of the antiferromagnet. In the case of a strong roughness, there arise static vortices at the surface and a 90° domain wall aligned parallel to the surface of the antiferromagnet. 相似文献
308.
L. I. Bryukvina E. A. Ermolaeva S. N. Pidgurskiĭ L. F. Suvorova V. M. Khulugurov 《Physics of the Solid State》2006,48(1):68-72
It was detected for the first time that films consisting of a transition-metal-based structure form (via thermal diffusion
of intracrystalline impurities) on the surface of alkali-halide (LiF, NaF) crystals activated by transition metals Co, Ni,
or Mn. The thickness, density, and composition of the films are shown to be different, depending on the heat treatment conditions.
The crystals were annealed at temperatures varying from 473 to 1073 K in vacuum and air. The surface structures forming upon
annealing in vacuum exhibit magnetic properties. The films were studied by optical, x-ray fluorescence, and electron spectroscopy
to reveal the mechanisms of transition-metal film formation during thermal annealing. 相似文献
309.
A general method for solving the problem of quantization of a top is proposed that allows for finding the Hamiltonian eigenfunctions in the form of polynomials of various degree n in the Cartesian coordinates with the use of the Lamé functions. All three coordinates x, y, and z are equivalently involved in computations, as well as their relations with ellipsoidal coordinates, which makes the computations symmetric. 相似文献
310.