全文获取类型
收费全文 | 365447篇 |
免费 | 3393篇 |
国内免费 | 1567篇 |
专业分类
化学 | 191582篇 |
晶体学 | 5292篇 |
力学 | 17341篇 |
综合类 | 66篇 |
数学 | 43749篇 |
物理学 | 112377篇 |
出版年
2020年 | 3320篇 |
2019年 | 3802篇 |
2018年 | 5327篇 |
2017年 | 5388篇 |
2016年 | 7119篇 |
2015年 | 3930篇 |
2014年 | 6527篇 |
2013年 | 14802篇 |
2012年 | 12222篇 |
2011年 | 14691篇 |
2010年 | 11114篇 |
2009年 | 11056篇 |
2008年 | 13993篇 |
2007年 | 13970篇 |
2006年 | 12873篇 |
2005年 | 11655篇 |
2004年 | 10724篇 |
2003年 | 9490篇 |
2002年 | 9539篇 |
2001年 | 10666篇 |
2000年 | 8019篇 |
1999年 | 5981篇 |
1998年 | 5173篇 |
1997年 | 5028篇 |
1996年 | 4847篇 |
1995年 | 4280篇 |
1994年 | 4344篇 |
1993年 | 4239篇 |
1992年 | 4513篇 |
1991年 | 4847篇 |
1990年 | 4565篇 |
1989年 | 4527篇 |
1988年 | 4378篇 |
1987年 | 4326篇 |
1986年 | 4187篇 |
1985年 | 5441篇 |
1984年 | 5495篇 |
1983年 | 4638篇 |
1982年 | 4913篇 |
1981年 | 4615篇 |
1980年 | 4247篇 |
1979年 | 4667篇 |
1978年 | 4996篇 |
1977年 | 5089篇 |
1976年 | 5246篇 |
1975年 | 4850篇 |
1974年 | 4874篇 |
1973年 | 5012篇 |
1972年 | 3973篇 |
1971年 | 3377篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
181.
182.
N. S. Oliveira J. Dorgan J. A. P. Coutinho A. Ferreira J. L. Daridon I. M. Marrucho 《Journal of Polymer Science.Polymer Physics》2007,45(5):616-625
The sorption of carbon dioxide in glassy Poly(lactic acid) (PLA) films was studied by quartz crystal microbalance (QCM) at high pressures. Two thermal treatments, melted and quenched, were performed in PLA with two different L:D contents, 80:20 and 98:2, films and compared with a third thermal protocol, annealed, and used in a previous work. The results obtained show that for pressures higher than 2 MPa, the carbon dioxide solubility is larger in PLA 80:20 than in PLA 98:2, indicating that the L:D plays a dominant role on this property. The thermal treatments only affect the gas solubility in PLA 98:2. Sorption isotherms at temperatures 303, 313, and 323 K, below the glass transition temperature of the polymer, and pressures up to 5 MPa were measured and analyzed with three different models, the dual‐mode sorption model, the Flory–Huggins equation, and a modified dual‐mode sorption model where the Henry's law term was substituted by the Flory–Huggins equation. This last model performs especially well for CO2 in PLA 80:20, due to the convex upward curvature of the solubility isotherms for that system. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 616–625, 2007 相似文献
183.
184.
This article describes the technique of fast atom bombardment mass spectrometry (FAB MS) and its applications to the analysis of organometallic and coordination complexes. Sections on ion generation and matrices are followed by a Periodic Group-based review of FAB MS results obtained from Transition Metal and Main Group compounds, organometallic cluster carbonyls and their derivatives, and salts of poly-oxo-anions. The literature has been surveyed from 1981 to approximately mid-1986. 相似文献
185.
186.
The trisilanol 1,3,5‐(HOi‐Bu2Si)3C6H3 ( 7 ), prepared in three steps from 1,3,5‐tribromobenzene via the intermediates 1,3,5‐(Hi‐Bu2Si)3C6H3 ( 8 ) and 1,3,5‐(Cli‐Bu2Si)3C6H3 ( 9 ) forms an equimolar complex with trans‐bis(4‐pyridyl)ethylene (bpe), 7 ·bpe, whose structure was investigated by X‐ray crystallography. The hydrogen‐bonded network features a number of SiO? H(H)Si and SiO? H hydrogen bridges. Evidence was found for cooperative strengthening within the sequential hydrogen bonds. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
187.
188.
K.T.A.L. Burm 《等离子体物理论文集》2007,47(6):458-464
The discharge behaviour of an atmospheric dielectric barrier parallel plate discharge, used for surface treatment, is studied. Since an uniform plasma is preferable for surface treatment, filaments must be avoided in the discharge. The occurrence of filaments can be detected by measuring the current flowing through the discharge. Current and voltage measurements give an indication of the power consumption by the plasma. The power consumption of the plasma as function of the applied frequency is examined. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
189.
Kryazhimskiy A. V. Maksimov V. I. 《Proceedings of the Steklov Institute of Mathematics》2006,253(1):S168-S184
A problem of guaranteeing control for a system of parabolic equations is considered. A solving algorithm based on the combination of real time reconstruction processes and feedback control is designed. 相似文献
190.