全文获取类型
收费全文 | 400792篇 |
免费 | 2806篇 |
国内免费 | 815篇 |
专业分类
化学 | 192845篇 |
晶体学 | 6265篇 |
力学 | 21625篇 |
综合类 | 13篇 |
数学 | 55994篇 |
物理学 | 127671篇 |
出版年
2021年 | 2774篇 |
2020年 | 2929篇 |
2019年 | 3513篇 |
2018年 | 11686篇 |
2017年 | 12242篇 |
2016年 | 9992篇 |
2015年 | 4191篇 |
2014年 | 6257篇 |
2013年 | 13790篇 |
2012年 | 14265篇 |
2011年 | 22884篇 |
2010年 | 15431篇 |
2009年 | 15685篇 |
2008年 | 20719篇 |
2007年 | 23347篇 |
2006年 | 11266篇 |
2005年 | 15000篇 |
2004年 | 11887篇 |
2003年 | 11326篇 |
2002年 | 9624篇 |
2001年 | 10281篇 |
2000年 | 7788篇 |
1999年 | 5729篇 |
1998年 | 4520篇 |
1997年 | 4614篇 |
1996年 | 4438篇 |
1995年 | 3941篇 |
1994年 | 4028篇 |
1993年 | 3754篇 |
1992年 | 4438篇 |
1991年 | 4650篇 |
1990年 | 4387篇 |
1989年 | 4442篇 |
1988年 | 4313篇 |
1987年 | 4327篇 |
1986年 | 4044篇 |
1985年 | 5092篇 |
1984年 | 5203篇 |
1983年 | 4279篇 |
1982年 | 4241篇 |
1981年 | 4069篇 |
1980年 | 3884篇 |
1979年 | 4484篇 |
1978年 | 4558篇 |
1977年 | 4597篇 |
1976年 | 4536篇 |
1975年 | 4252篇 |
1974年 | 4202篇 |
1973年 | 4341篇 |
1972年 | 3131篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
Coulomb systems in which the particles interact through thed-dimensional Coulomb potential but are confined in a flat manifold of dimensiond–1 are considered. The actual Coulomb potential acting is defined by particular boundary conditions involving a characteristic macroscopic distanceW in the direction perpendicular to the manifold: either it is periodic of periodW in that direction, or it vanishes on one ideal conductor wall parallel to the manifold at a distanceW from it, or it vanishes on two parallel walls at a distanceW from each other with the manifold equidistant from them. Under the assumptions that classical equilibrium statistical mechanics is applicable and that the system has the macroscopic properties of a conductor, it is shown that the suitably smoothed charge correlation function is universal, and that the free energy and the grand potential have universal dependences onW (universal means independent of the microscopic detail). The casesd=2 are discussed in detail, and the generic results are checked on an exactly solvable model. The cased=3 of a plane parallel to an ideal conductor is also explicitly worked out.Laboratoire associé au Centre National de la Recherche Scientifique-URA D0063. 相似文献
993.
A. S. Lobach B. P. Tarasov Yu. M. Shul'ga A. A. Perov A. N. Stepanov 《Russian Chemical Bulletin》1996,45(2):464-465
Fullerene deuteride was obtained by the reaction of deuterium with solid palladium fulleride C60Pd4.9 under fairly mild conditions. The compound was identified by FD-MS, UV-Vis and IR spectroscopies, and TLC.Translated from Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 483–484, February, 1996 相似文献
994.
995.
Thermoelastic stress analysis was used to document the effect of composite damage on the stress distribution in three ceramic matrix composites. Composite damage was found to significantly alter the thermoelastic response of each material, with the greatest effect noted in SiC/CAS. Thermoelastic imaging of these materials affords a more complete picture of how the various damage mechanisms affect the stress distribution. In particular, a stress concentration factor computed from thermoelastic images, serves as an indicator of stress redistribution. The stress concentration factors were computed by comparing notch root to far field temperatures, and monitored after the introduction of various amounts of damage. In each material, the stress concentration factor diminished as the damaging load approached the ultimate stress. Reduction in the stress concentration is associated with local changes in modulus, mechanistically arising from combinations of fiber, matrix and interface fracture. Stress redistribution occurs as a consequence of modulus changes, leading to lower notch sensitivity in each of the tested composites. 相似文献
996.
Alexander N Shivanyuk Dmitry M Rudkevich David N Reinhoudt 《Tetrahedron letters》1996,37(52):9341-9344
An assembly of cation receptor 1 and anion receptor 2 via the hydrogen bonding melamine-barbiturate structural motif complexes sodium thiocyanate, sodium iodide, and sodium azide in apolar solvents. 相似文献
997.
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
998.
999.
Methods are proposed for determining the diffusion coefficients of adsorbed molecules and the adsorption isotherms from given concentrations of the solutes in the external solution. The methods are based on a comparison of experimental data with the numerical results produced by a mathematical model of internal-diffusion kinetics of adsorption from a constant bounded volume.Translated from Vychislitel'naya i Prikladnaya Matematika, No. 66, pp. 41–46, 1988. 相似文献
1000.
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