全文获取类型
收费全文 | 209467篇 |
免费 | 1805篇 |
国内免费 | 592篇 |
专业分类
化学 | 105134篇 |
晶体学 | 3366篇 |
力学 | 9404篇 |
综合类 | 5篇 |
数学 | 23823篇 |
物理学 | 70132篇 |
出版年
2021年 | 1688篇 |
2020年 | 1842篇 |
2019年 | 2050篇 |
2018年 | 2821篇 |
2017年 | 2720篇 |
2016年 | 3949篇 |
2015年 | 2435篇 |
2014年 | 3804篇 |
2013年 | 9546篇 |
2012年 | 7490篇 |
2011年 | 9057篇 |
2010年 | 6241篇 |
2009年 | 6061篇 |
2008年 | 8205篇 |
2007年 | 8362篇 |
2006年 | 7972篇 |
2005年 | 7090篇 |
2004年 | 6589篇 |
2003年 | 5774篇 |
2002年 | 5612篇 |
2001年 | 6507篇 |
2000年 | 4988篇 |
1999年 | 3847篇 |
1998年 | 3084篇 |
1997年 | 3090篇 |
1996年 | 2838篇 |
1995年 | 2655篇 |
1994年 | 2490篇 |
1993年 | 2375篇 |
1992年 | 2744篇 |
1991年 | 2711篇 |
1990年 | 2651篇 |
1989年 | 2451篇 |
1988年 | 2493篇 |
1987年 | 2495篇 |
1986年 | 2323篇 |
1985年 | 3018篇 |
1984年 | 3282篇 |
1983年 | 2695篇 |
1982年 | 2862篇 |
1981年 | 2816篇 |
1980年 | 2689篇 |
1979年 | 2774篇 |
1978年 | 2888篇 |
1977年 | 2852篇 |
1976年 | 2933篇 |
1975年 | 2706篇 |
1974年 | 2683篇 |
1973年 | 2804篇 |
1972年 | 1796篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
211.
We propose a complex approach to evaluating afunction sum of two noncommuting non-Hermitianoperators. We propose an explicit expansion of theevolution operator in the case of the neutral K-mesonsystem influenced by an external interaction. Theimportance is pointed out of considering the algebraicexpansion of the time evolution operator whenever thedynamics decouples the internal transitions andcenter-of-mass motion. 相似文献
212.
213.
Polarization dynamics are considered in the presence of an anisotropic Kerr non-linearity in the most common semiconductor waveguide geometry. The equations of motion are formulated in terms of Stokes polarization parameters and their Hamiltonian form is derived. Stationary solutions and their stability are found for plane-wave propagation. It is found that the non-integrable problem of mixed-polarization spatial soliton dynamics can be largely explained in terms of the equivalent plane-wave solutions. 相似文献
214.
D. B. Saakian 《JETP Letters》1998,67(6):440-444
A layered random spin model, equivalent to the generalized random energy model (GREM), is introduced. In analogy with diluted
spin systems, a diluted GREM (DGREM) is constructed. It can be applied to calculate approximately the thermodynamic properties
of spin glass models in low dimensions. For the Edwards-Anderson model it gives the correct critical dimension and 5% accuracy
for the ground state energy in two dimensions.
Pis’ma Zh. éksp. Teor. Fiz. 67, No. 6, 415–419 (25 March 1998)
Published in English in the original Russian journal. Edited by Steve Torstveit. 相似文献
215.
The 351 nm laser-damage thresholds (at 0.7 nm pulse length) of monomeric liquid crystals are reported and results from aromatic-core samples are compared with those from fully saturated systems. The role of π-electron conjugation is examined and identified as the key cause for laser damage. For UV laser compatibility of devices, the damage behaviour of an alignment-layer polymer (nylon 6/6) was also investigated. 相似文献
216.
Translated from Vychislitel'nye Kompleksy i Modelirovanie Slozhnykh Sistem, pp. 138–141, Moscow State University, 1989. 相似文献
217.
Two organic scintillators — NE104 and a liquid solution of 2,5 diphenyloxazole (PPO) — were investigated through positron annihilation spectroscopy to study the influence of the structural order on the magnetic quenching effect on positron bound systems in solids.Preliminary note in [11] 相似文献
218.
M. D. Bavizhev V. L. Burlikov V. I. Simanchuk A. V. Kargapol'tsev 《Russian Physics Journal》1991,34(8):727-730
Experimental data on the generation of acoustic radiation in solid targets by pulsed high-energy proton beams are outlined. The features of ultrasound generation in solids by beams of heavy charged particles are analyzed, and the possibility of using the acoustic effect of heavy charged particles to investigate the interaction between radiation and condensed media and to determine particle energies is shown.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 8, pp. 95–99, August, 1991. 相似文献
219.
220.