全文获取类型
收费全文 | 661347篇 |
免费 | 7998篇 |
国内免费 | 1999篇 |
专业分类
化学 | 344584篇 |
晶体学 | 9937篇 |
力学 | 30591篇 |
综合类 | 20篇 |
数学 | 81955篇 |
物理学 | 204257篇 |
出版年
2021年 | 5932篇 |
2020年 | 6438篇 |
2019年 | 7028篇 |
2018年 | 9239篇 |
2017年 | 9256篇 |
2016年 | 13628篇 |
2015年 | 8397篇 |
2014年 | 13229篇 |
2013年 | 31282篇 |
2012年 | 23943篇 |
2011年 | 29175篇 |
2010年 | 20918篇 |
2009年 | 20707篇 |
2008年 | 26480篇 |
2007年 | 26376篇 |
2006年 | 24303篇 |
2005年 | 21467篇 |
2004年 | 20076篇 |
2003年 | 17699篇 |
2002年 | 17700篇 |
2001年 | 20001篇 |
2000年 | 15174篇 |
1999年 | 11939篇 |
1998年 | 9967篇 |
1997年 | 9621篇 |
1996年 | 9197篇 |
1995年 | 8118篇 |
1994年 | 8094篇 |
1993年 | 7800篇 |
1992年 | 8590篇 |
1991年 | 8826篇 |
1990年 | 8447篇 |
1989年 | 8199篇 |
1988年 | 8050篇 |
1987年 | 8020篇 |
1986年 | 7594篇 |
1985年 | 9806篇 |
1984年 | 9994篇 |
1983年 | 8098篇 |
1982年 | 8264篇 |
1981年 | 8019篇 |
1980年 | 7601篇 |
1979年 | 8230篇 |
1978年 | 8351篇 |
1977年 | 8239篇 |
1976年 | 8158篇 |
1975年 | 7672篇 |
1974年 | 7574篇 |
1973年 | 7558篇 |
1972年 | 5379篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
Luminescence properties of anodic aluminum oxide films with organic luminophores embedded into pores
V. V. Gruzinskii A. V. Kukhto A. M. Mozalev V. F. Surganov 《Journal of Applied Spectroscopy》1997,64(4):497-502
Luminescence properties of porous anodic aluminum oxide films formed in a 0.6 M solution of citric acid and luminescence of
paraterphenyl, perylene, coumarin 7, and rhodamine 6G dyes adsorbed by the films are investigated. The nature of emitting
centers in anodic aluminum oxide is revealed. Intense photoluminescence of all tested dyes embedded into pores of anodic aluminum
oxide has been found. A redshift of fluorescence spectra of dyes adsorbed by the matrix and emergence of an additional longwave
band have been detected. Data obtained can be used in developing new thin-film luminescent coatings for future applications
in optoelectronics and molecular electronics.
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No 4, pp. 483–488, July–August, 1997. 相似文献
993.
I. Peshko G. Galich M. Lopiychuk A. Khizhnyak V. Nakvasuk 《Optics & Laser Technology》1997,29(4):211-215
A laser system containing four CW Nd:YAG double-rod lasers, transforming optics and a fibre with input-output optics has been designed and investigated. It is shown that reduction of the beam parameter product of the non-Gaussian beams in the image space of the lens has made it possible to collect the emission of four lasers to the same fibre. Independent laser operation has provided the output power control in the range of 10–900 W with a stable light spot size on the input end of the fibre. 相似文献
994.
N. P. Venediktov M. Yu. Glyavin V. E. Zapevalov A. N. Kuftin A. S. Postnikova M. V. Yulpatova 《Radiophysics and Quantum Electronics》1997,40(4):336-342
A scheme for automated study of current-voltage characteristics of gyroresonance devices is developed. The effective emission
spread at the cathodes of powerful gyrotrons is studied by analysis of current-voltage characteristics. Experimental data
on the effective emission spread parameter for different modes are given. The permissible emission spread at the cathodes
of powerful gyrotrons is estimated, and the dependence of the electron beam parameters on the cathode emission spread is presented.
A complex measurement technique showing the contribution of different physical mechanisms to the cathode emission spread is
proposed.
Institute of Applied Physics, Russian Academy of Sciences, Nizhny Novgorod, Russia. Translated from Izvestiya Vysshikh Uchebnykh
Zavedenii, Radiofizika, Vol. 40, No. 4, pp. 506–516, April, 1997. 相似文献
995.
Processing-induced residual strains in solid cylinders of Nickel 200 were investigated using phase shifting moiré interferometry. Two different experimental approaches were used to study the strains produced during Tungsten-inert gas spot welding. A comparison of results for a ‘hot/fast’ and a ‘cool/slow’ weld demonstrate the capabilities of the general approach. Both experimental methods revealed distinct differences in the residual displacement and strain fields between the two types of welds. 相似文献
996.
In this article we have studied the nonlinear interaction between ellipticity and dissipation in a set of model equations (1.1) and established the relation between this interaction and chaos. In addition to theoretical investigations, extensive numerical simulations with these equations have been made, and different routes to chaos have been found. The numerical studies have revealed the chaotic nature of the solutions. 相似文献
997.
A.M. van der Kraan 《Hyperfine Interactions》1998,111(1-4):23-34
In modern society the application of catalysts, and hence, research in the field of catalysis, is becoming more and more important. In the strongly increasing chemical industry most reaction processes are performed with the aid of catalysts. Knowledge about the structure of the active sites present at the surface of catalysts will facilitate the design of new catalysts with better performances. Such knowledge can be obtained by Mössbauer spectroscopy, which is an excellent in-situ characterization technique due to the high penetrating power of the γ-radiation used and the sensitivity of the spectral parameters for the chemical state and local environment of the Mössbauer atoms. 相似文献
998.
We consider the application of asymptotic methods of nonlinear mechanics (the Krylov-Bogolyubov-Mitropol'skii method) and
the method of separation of motions in nonlinear systems for the construction of an approximate solution of a nonlinear equation
that describes a nonstationary wave process.
Translated from Ukrainskii Matematicheskii Zhurnal, Vol. 50, No. 3, pp. 357–371, March, 1998. 相似文献
999.
T. N. Mamedov V. N. Duginov A. V. Stoykov I. L. Chaplygin D. Herlach U. Zimmermann V. N. Gorelkin J. Major M. Schefzik 《JETP Letters》1998,68(1):64-70
The residual polarization of negative muons in crystal silicon samples with phosphorus (P: 1.6×1013 cm−3) and antimony (Sb: 2×1018 cm−3) impurities is investigated. The measurements are made in a 1000 G magnetic field oriented in a direction transverse to the
muon spin in the temperature range 4–300 K. The relaxation rate and shift of the precession frequency in the silicon sample
with the phosphorus impurity are measured more accurately than previously. It is found that in antimony-doped silicon the
acceptor center
μ
A1 at temperatures below 30 K can be in both ionized and neutral states. The experimental data are interpreted on the basis
of spin-lattice relaxation of the magnetic moment of an acceptor center, formation of acceptor-donor pairs, and recombination
of charge carriers at the acceptor. Preliminary measurements showed a nonzero residual polarization of negative muons in germanium.
Pis’ma Zh. éksp. Teor. Fiz. 68, No. 1, 61–66 (10 July 1998) 相似文献
1000.
S. M. Stishov 《JETP Letters》1998,67(1):90-94
Explanations are given for why there is no real first-order phase transition in the one-component plasma (OCP) model. The
fluid (liquid) and crystalline states of the OCP observed in computer experiments are not in equilibrium, on account of instability
of the system. However, specific features of the free energy suggest that some sort of a “virtual” phase transition occurs
in the model. Such a transition can be turned real by choosing the right form of the background energy.
Pis’ma Zh. éksp. Teor. Fiz. 67, No. 1, 82–85 (10 January 1997)
Published in English in the original Russian journal. Edited by Steve Torstveit. 相似文献