全文获取类型
收费全文 | 641157篇 |
免费 | 5844篇 |
国内免费 | 1491篇 |
专业分类
化学 | 323501篇 |
晶体学 | 9445篇 |
力学 | 31975篇 |
综合类 | 16篇 |
数学 | 85049篇 |
物理学 | 198506篇 |
出版年
2021年 | 5796篇 |
2020年 | 6424篇 |
2019年 | 7247篇 |
2018年 | 9955篇 |
2017年 | 9900篇 |
2016年 | 14066篇 |
2015年 | 7938篇 |
2014年 | 13178篇 |
2013年 | 28529篇 |
2012年 | 22472篇 |
2011年 | 27070篇 |
2010年 | 20259篇 |
2009年 | 20334篇 |
2008年 | 25489篇 |
2007年 | 25083篇 |
2006年 | 23034篇 |
2005年 | 20368篇 |
2004年 | 19126篇 |
2003年 | 17088篇 |
2002年 | 17257篇 |
2001年 | 18527篇 |
2000年 | 14322篇 |
1999年 | 11050篇 |
1998年 | 9556篇 |
1997年 | 9212篇 |
1996年 | 8714篇 |
1995年 | 7864篇 |
1994年 | 7822篇 |
1993年 | 7602篇 |
1992年 | 8188篇 |
1991年 | 8554篇 |
1990年 | 8280篇 |
1989年 | 8119篇 |
1988年 | 7916篇 |
1987年 | 7869篇 |
1986年 | 7388篇 |
1985年 | 9288篇 |
1984年 | 9520篇 |
1983年 | 7763篇 |
1982年 | 8005篇 |
1981年 | 7710篇 |
1980年 | 7212篇 |
1979年 | 7919篇 |
1978年 | 8125篇 |
1977年 | 8128篇 |
1976年 | 8119篇 |
1975年 | 7505篇 |
1974年 | 7361篇 |
1973年 | 7474篇 |
1972年 | 5723篇 |
排序方式: 共有10000条查询结果,搜索用时 62 毫秒
201.
The results of optical study and quantum-chemical simulation of a conjugated organic system, 2-cyclooctylamino-5-nitropyridine (COANP)-fullerene, performed to determine its potential for application as a limiter of visible and near-IR laser radiation and as a material for diffraction elements in systems for reversible recording of optical information, are presented. Complexation between a COANP molecule and fullerene is considered as one of the main mechanisms responsible for the corresponding properties of this system. For the first time, nonlinear optical characteristics of COANP-C60 and COANP-C70 systems are comparatively studied and the intermolecular interaction between a COANP molecule and fullerene is analyzed on the quantum-chemical level. 相似文献
202.
203.
Maria G. Semenova Larisa E. Belyakova Anna S. Antipova Yu. N. Polikarpov Lida Klouda Anna Markovic Michael M. Il'in 《Colloids and surfaces. B, Biointerfaces》2003,31(1-4):47-54
We report on the effect of commercially important polysaccharides (maltodextrins with variable dextrose equivalent (Paselli SA-2, MD-6 and MD-10) on the surface activity at the air–water interface of small-molecule surfactants (sms), possessing different hydrophobic–lipophilic balance ((SSL (Na+), the main component is a sodium salt of stearol–lactoyl lactic acid, and PGE (080), polyglycerol ester of C18 fatty acid), and widely used in food products. A marked change of the surface activity of sms was found in the presence of maltodextrins by tensiometry. The combined data of laser multiangle light scattering and mixing calorimetry have suggested that this result is governed by specific complex formation between maltodextrins and sms in aqueous medium. Measurements have been made of the molar mass, the second virial coefficient and the enthalpy of intermolecular interactions in aqueous solutions. The implication of a degree of polymerization of maltodextrins in this phenomenon was shown. The interrelation between the molecular parameters of the formed complexes and their surface activity at the air–water interface has been revealed and discussed. 相似文献
204.
We prove new theorems on the justification of the averaging method for multifrequency oscillation systems with pulse influence at fixed times. 相似文献
205.
206.
V. L. Tsymbalenko 《JETP Letters》2003,78(8):493-496
The kinetics of formation of an anomalous phase from a solution with a small 3He impurity was studied in the temperature range 0.2–0.7 K up to a supersaturation of ~30 mbar. The phase diagram was determined for normal and anomalous growths. It is found that, in the presence of impurities, the formation of a fast-growing state is retarded. This experimental fact indicates that the dissipative processes in fluids have an appreciable effect on the phase formation kinetics. The retardation is, possibly, caused by the direct interaction of an impurity with the crystal surface. 相似文献
207.
Makarov V. L. Khlobystov V. V. Kashpur E. F. Mikhal'chuk B. R. 《Ukrainian Mathematical Journal》2003,55(6):942-955
We construct an integral Newton-type interpolation polynomial with a continual set of nodes. This interpolant is unique and preserves an operator polynomial of the corresponding degree. 相似文献
208.
M. M. Glazov 《Physics of the Solid State》2003,45(6):1162-1165
A precession mechanism of spin relaxation of conduction electrons in a square quantum well is analyzed. The dependence of the spin relaxation time on the width of a quantum well and the height of its barriers is calculated under the assumption that the electron-electron collisions dominate over other processes of carrier scattering. 相似文献
209.
210.
P L Melgarejo M Ternero I Gracia 《International journal of environmental analytical chemistry》1986,24(4):283-295
A study of the atmospheric pollution by suspended particulate lead in the city of Seville, Spain, was carried out during the period between March 1983 and February 1984. The results obtained from seven sampling stations allowed us to study the site to site variations; there are two locations with average annual concentrations higher than 2 micrograms X m-3. In one station, the meteorological and traffic effects and relationship with other traffic-related pollutants, were investigated. The regression analyses performed on the average monthly data have shown an inverse correlation with wind speed and temperature and a direct correlation with carbon monoxide and smoke concentrations, but no significant correlation was found with the lead deposition levels. 相似文献