全文获取类型
收费全文 | 265277篇 |
免费 | 890篇 |
国内免费 | 285篇 |
专业分类
化学 | 116513篇 |
晶体学 | 3763篇 |
力学 | 15982篇 |
综合类 | 7篇 |
数学 | 43881篇 |
物理学 | 86306篇 |
出版年
2019年 | 2290篇 |
2018年 | 10871篇 |
2017年 | 11629篇 |
2016年 | 7726篇 |
2015年 | 2549篇 |
2014年 | 3693篇 |
2013年 | 7142篇 |
2012年 | 9361篇 |
2011年 | 17665篇 |
2010年 | 11663篇 |
2009年 | 12017篇 |
2008年 | 15703篇 |
2007年 | 18937篇 |
2006年 | 5794篇 |
2005年 | 10449篇 |
2004年 | 7570篇 |
2003年 | 7446篇 |
2002年 | 5839篇 |
2001年 | 5140篇 |
2000年 | 4006篇 |
1999年 | 2865篇 |
1998年 | 2645篇 |
1997年 | 2474篇 |
1996年 | 2441篇 |
1995年 | 2156篇 |
1994年 | 2100篇 |
1993年 | 2122篇 |
1992年 | 2146篇 |
1991年 | 2457篇 |
1990年 | 2387篇 |
1989年 | 2472篇 |
1988年 | 2361篇 |
1987年 | 2387篇 |
1986年 | 2207篇 |
1985年 | 2752篇 |
1984年 | 2783篇 |
1983年 | 2416篇 |
1982年 | 2463篇 |
1981年 | 2369篇 |
1980年 | 2171篇 |
1979年 | 2506篇 |
1978年 | 2668篇 |
1977年 | 2672篇 |
1976年 | 2800篇 |
1975年 | 2591篇 |
1974年 | 2519篇 |
1973年 | 2727篇 |
1972年 | 2192篇 |
1971年 | 2000篇 |
1970年 | 1880篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
981.
The DELPHI Collaboration J. Abdallah et al. 《The European Physical Journal C - Particles and Fields》2003,27(2):153-172
A search for sleptons, neutralinos, charginos, sgoldstinos and heavy stable charged sleptons in the context of scenarios
where the lightest supersymmetric particle is the gravitino, is presented. Data collected during 2000 with the DELPHI detector
at centre-of-mass energies from 204 to 208 GeV were analysed and combined with all the data collected from 1995 to 1999 at
lower energies. No evidence for the production of sleptons, neutralinos and charginos has been found, therefore new limits
on the mass of these supersymmetric particles and on the model parameter space are set. The search for heavy stable charged
sleptons also updates the stable sleptons mass limit. The absence of evidence for sgoldstino production allows limits to be
set on its mass and on the scale of supersymmetry breaking.
Received: 6 November 2002 / Published online: 14 February 2003 相似文献
982.
B. Aneva 《The European Physical Journal C - Particles and Fields》2003,31(3):403-414
Deformed squeezed states are introduced as the q-analogues of the conventional undeformed harmonic oscillator algebra squeezed states. It is shown that the boundary vectors in the matrix-product states approach to multiparticle diffusion processes are deformed coherent or squeezed states of a deformed harmonic oscillator algebra. A deformed squeezed and coherent-states solution to the n-species stochastic diffusion boundary problem is proposed and studied.Received: 31 January 2003, Published online: 10 October 2003 相似文献
983.
We present a full treatment of the microcanonical ensemble of the ideal hadron-resonance gas starting from a quantum-mechanical formulation which is appropriate for the statistical model of hadronization. By using a suitable transition operator for hadronization we are able to recover the results of the statistical theory, particularly the expressions of the rates of different channels. Explicit formulae are obtained for the phase space volume or density of states of the ideal relativistic gas in quantum statistics as a cluster decomposition, generalizing previous ones in the literature. The problem of the computation of averages in the hadron gas microcanonical ensemble and the comparison with canonical ones will be the main subject of a forthcoming second paper.Received: 8 July 2003, Revised: 17 October 2003, Published online: 5 May 2004 相似文献
984.
Pyroelectric effect in lead-magnoniobate-based solid solutions 总被引:1,自引:0,他引:1
E. P. Smirnova S. E. Aleksandrov K. A. Sotnikov A. A. Kapralov A. V. Sotnikov 《Physics of the Solid State》2003,45(7):1305-1309
A coordinated study of the dielectric, electrostriction, and pyroelectric properties of the lead-magnoniobate-based ceramic solid solutions 0.9PbMg1/3Nb2/3O3-0.1PbTiO3 and 0.55PbMg1/3Nb2/3O3-0.45PbSc1/2Nb1/2O3 conducted at the relaxor transition temperatures is reported. Electromechanical coupling stimulated by the giant electrostriction effect is shown to play an essential part in the pyroelectric effect. 相似文献
985.
986.
The equilibrium conversion of nitriles in the reaction of cyanoalkylphosphonates with methanol in the presence of sodium methylate, as determined by potentiometric titration with perchloric acid in nitromethane, varies from 58 to 17.7%. The practical yields of imidates were evaluated by a preparative procedure of isolation of purified imidates from the reaction mixtures (56-14%). Because of the low conversions of nitriles, the reaction is expedient to use only for preparing alkyl (dialkoxyphosphoryl)acetimidates. 相似文献
987.
A method for suppressing self-modulation in backward-wave tubes is proposed. Additional delay is introduced into the feedback
circuit, owing to which the output signal amplitude affects the electron beam current that enters into the interaction space.
Numerical simulations demonstrate that the operating current in the single-frequency oscillation mode may be increased roughly
twofold. 相似文献
988.
We propose iteration methods for solving the Dirichlet problem in domains with involved geometry. Such problems arise in relation to the problem of optimizing quantum dot and antidot infrared detectors. We estimate the deviation of an approximate solution from the exact solution. 相似文献
989.
We again consider the problem of the light-cone expansion for products of currents and explain the motivations making a rethinking of old results relevant today. 相似文献
990.