全文获取类型
收费全文 | 282644篇 |
免费 | 5282篇 |
国内免费 | 4284篇 |
专业分类
化学 | 154438篇 |
晶体学 | 4246篇 |
力学 | 11197篇 |
综合类 | 340篇 |
数学 | 33822篇 |
物理学 | 88167篇 |
出版年
2021年 | 2126篇 |
2020年 | 2540篇 |
2019年 | 2610篇 |
2018年 | 3212篇 |
2017年 | 3246篇 |
2016年 | 5006篇 |
2015年 | 3745篇 |
2014年 | 5305篇 |
2013年 | 13711篇 |
2012年 | 10118篇 |
2011年 | 12415篇 |
2010年 | 8197篇 |
2009年 | 8023篇 |
2008年 | 11462篇 |
2007年 | 11437篇 |
2006年 | 10491篇 |
2005年 | 9619篇 |
2004年 | 8411篇 |
2003年 | 7385篇 |
2002年 | 7254篇 |
2001年 | 8142篇 |
2000年 | 6358篇 |
1999年 | 4830篇 |
1998年 | 3990篇 |
1997年 | 3960篇 |
1996年 | 3812篇 |
1995年 | 3534篇 |
1994年 | 3438篇 |
1993年 | 3547篇 |
1992年 | 3743篇 |
1991年 | 3656篇 |
1990年 | 3483篇 |
1989年 | 3407篇 |
1988年 | 3466篇 |
1987年 | 3312篇 |
1986年 | 3188篇 |
1985年 | 4377篇 |
1984年 | 4534篇 |
1983年 | 3743篇 |
1982年 | 4091篇 |
1981年 | 4008篇 |
1980年 | 3847篇 |
1979年 | 3845篇 |
1978年 | 4097篇 |
1977年 | 3903篇 |
1976年 | 4067篇 |
1975年 | 3643篇 |
1974年 | 3762篇 |
1973年 | 4079篇 |
1972年 | 2443篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
181.
It has been shown by Yu. M. Golubev, M. I. Kolobov, and I. V. Sokolov, Zh. éksp. Teor. Fiz. 111, 1579 (1997) [JETP 84, 864 (1997)], that when an optical cavity is excited by external radiation from a sub-Poisson laser the cavity mode may be
in either a sub-Poisson or a Poisson stationary state. This is not important for a resonant medium which is excited into the
upper laser level while interacting with this mode inside the cavity. The degree of regularity of the excitation will be identical
to that of the initial light flux incident on the cavity, and this ultimately ensures the same sub-Poisson lasing as for strictly
regular pumping of the resonant medium.
Zh. éksp. Teor. Fiz. 113, 1223–1234 (April 1998) 相似文献
182.
R. L. Stratonovich 《Theoretical and Mathematical Physics》1997,111(2):521-533
A dynamically verified statistical theory of moderately dense gases developed by Bogoliubov and others is generalized to the
case of bimolecular chemical reactions in a gas. The corresponding chain of BBGKY equations is derived. From this chain, the
kinetic equations for one-molecule distribution functions are obtained in the approximation of bimolecular and trimolecular
interactions.
Deceased.
Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 111, No. 2, pp. 163–178, May, 1997. 相似文献
183.
184.
G. Hinze R. Böhmer G. Diezemann H. Sillescu 《Journal of magnetic resonance (San Diego, Calif. : 1997)》1998,131(2):218-223
Four-time stimulated echo experiments have been used to monitor the temporal evolution of the reorientation rates of deuterated molecules or colloidal suspensions. We present extended phase cycles for this seven-pulse experiment. In order to test its performance three vastly different materials are chosen. These include a crystal in which the molecules carry out well-defined 180° flips and a supercooled liquid characterized by a distribution of jump angles centered around 10°. As an example for rotational diffusion, data on a concentrated suspension of polystyrene spheres in a viscous medium are presented. 相似文献
185.
186.
G. Garcia-Belmonte J. Bisquert L. M. Navarro J. R. Jurado F. M. B. Marques 《Ionics》1995,1(5-6):377-383
In ionic conductors, long range-migrating charges are a main cause of polarization processes. This has complicated, up to
date, the study of ionic thermocurrents (ITC) in solid electrolytes. However, the method is appealing, as it probes directly
charge-formation phenomena that are important both from a scientific point of view and for applications.
This work reports on the observation of ITC in solid electrolytes. Under appropriate experimental conditions, the ITC response
of a zirconia sample electroded with platinum is a reproducible one, thus opening the way to a new characterization method
that may complement other well established methods, such as Impedance Spectroscopy and a number of electrochemical techniques.
The general trends of the response, which is composed of two well resolved ITC peaks, is discussed. One of them, taking place
at higher temperatures, conforms to the standard shape of a first order kinetics depolarization process.
Paper presented at the 2nd Euroconference on Solid State Ionics, Funchal, Madeira, Portugal, Sept. 10–16, 1995 相似文献
187.
188.
The results of Monte Carlo simulations of the beta dose rate to enamel are presented. The dose rates are the most comprehensive to date, incorporating the beta spectrum from 21 different radionuclides, all internal conversion and Auger electrons, the majority of the bremsstrahlung radiation, effects due to radon loss in the uranium series, and variations in the moisture content of the sediment. Applications to a new dating technique in archaeology using electron spin resonance and beta-gradient isochrons are discussed. 相似文献
189.
R. Gerbaldo G. Ghigo G. Giunchi L. Gozzelino F. Laviano E. Mezzetti 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,26(3):297-300
We present results from an extended magneto-optical (MO) analysis of two samples cut from high-density pellets of MgB2. The first sample was studied in order to show that no matter how large the sample is and despite the bulk granularity, the
material enters into a critical state in a crystal-like fashion. The second sample was chosen for the quantitative analysis.
A numerical approach based on an inverted 2D Biot-Savart model was used to calculate the current paths across the homogeneous
polycrystalline bulk, as well as in the vicinity and across some morphological defects. Local current densities in the homogeneous
part were estimated as a function of the applied magnetic field at different temperatures, in three regimes: below full penetration,
at full penetration and above full penetration, respectively. A hypothesis of interpretation of the apparent absence of magnetic
granularity inside the polycrystalline microstructure is presented. It is related to a critical state likely reached by a
network of strongly coupled Josephson junctions.
Received 31 May 2001 and Received in final form 5 December 2001 相似文献
190.
R. Enberg L. Motyka G. Poludniowski 《The European Physical Journal C - Particles and Fields》2002,26(2):219-228
Diffractive heavy vector meson photoproduction accompanied by proton dissociation is studied for arbitrary momentum transfer.
The process is described by the non-forward BFKL equation, for which a complete analytical solution is found, giving the scattering
amplitude. The impact of non-leading corrections to the BFKL equation is also analysed. Results are compared to the HERA data
on production.
Received: 2 July 2002 / Revised version: 29 August 2002 / Published online: 18 October 2002 相似文献