全文获取类型
收费全文 | 605223篇 |
免费 | 7179篇 |
国内免费 | 1026篇 |
学科分类
工业技术 | 613428篇 |
出版年
2021年 | 5431篇 |
2020年 | 4006篇 |
2019年 | 5264篇 |
2018年 | 13842篇 |
2017年 | 14150篇 |
2016年 | 12654篇 |
2015年 | 6276篇 |
2014年 | 10306篇 |
2013年 | 26144篇 |
2012年 | 17236篇 |
2011年 | 25759篇 |
2010年 | 21491篇 |
2009年 | 22559篇 |
2008年 | 23013篇 |
2007年 | 24001篇 |
2006年 | 16316篇 |
2005年 | 16714篇 |
2004年 | 15259篇 |
2003年 | 14832篇 |
2002年 | 13721篇 |
2001年 | 12897篇 |
2000年 | 12441篇 |
1999年 | 12023篇 |
1998年 | 27651篇 |
1997年 | 20040篇 |
1996年 | 15632篇 |
1995年 | 11919篇 |
1994年 | 10775篇 |
1993年 | 10525篇 |
1992年 | 8248篇 |
1991年 | 8037篇 |
1990年 | 7937篇 |
1989年 | 7670篇 |
1988年 | 7392篇 |
1987年 | 6658篇 |
1986年 | 6458篇 |
1985年 | 7328篇 |
1984年 | 6640篇 |
1983年 | 6358篇 |
1982年 | 5716篇 |
1981年 | 5845篇 |
1980年 | 5586篇 |
1979年 | 5689篇 |
1978年 | 5634篇 |
1977年 | 6149篇 |
1976年 | 7654篇 |
1975年 | 5070篇 |
1974年 | 4867篇 |
1973年 | 4943篇 |
1972年 | 4256篇 |
排序方式: 共有10000条查询结果,搜索用时 625 毫秒
991.
The dynamic and equilibrium swelling behavior of polystyrene microparticles crosslinked with divinyl benzene was investigated in methyl ethyl ketone and cyclohexane. The dynamic studies gave new information about the mechanism of penetrant transport in this polymer. The equilibrium studies were used to determine important parameters of the crosslinked structure of these systems, including the average molecular weight between crosslinks, M?c 相似文献
992.
Dynamic mechanical properties have been investigated for interpenetrating-network systems based on polyol-cured polyurethanes (PU) and 2 to 1 n-butyl acrylate-n-butyl methacrylate (Ac) networks. The systems were formed simultaneously (SIN) from all of the precursors and reactants for both networks in the same vessel, and sequentially (SIPN) by swelling a precured PU with the reactants that will form the Ac network. If the Ac network is formed after gelation of the PU, the IPNs are transparent and appear to have single T (tan δmax) between those of the homonetworks; visible-phase separation occurs if the Ac is intentionally polymerized prior to PU gelation. Damping curves were lower and broader and the T (tan δmax) and rubber moduli were higher for the SIN than for the SIPN systems. Up to 65 percent Ac, the T (tan δmax) data for both SIN and SIPN fit the Gordon-Taylor equation if a T (tan δmax) for the Ac homonetwork 7°C higher than observed is used, suggesting a higher crosslink density for the Ac network under these conditions. The differences in properties of the SIN and SIPN are assumed to be dependent on sample homogeneity and upon the presence of a tin catalyst in the SIN preparation. This can result in limited Ac-network formation and consequent phase separation before PU gelation has occurred, and the catalyst may also increase the extent of interaction, such as grafting or hydrogen-bond formation between the networks. 相似文献
993.
Translated from Atomnaya Énergiya, Vol. 66, No. 6, pp. 423–424, June, 1989. 相似文献
994.
995.
A. A. Konstantinov N. V. Kurenkov A. B. Malinin T. E. Sazonova S. V. Sepman 《Atomic Energy》1989,67(3):696-698
Translated from Atomnaya Énergiya, Vol. 67, No. 3, pp. 215–216, September, 1989. 相似文献
996.
997.
998.
V. I. Kusov A. K. Gruznov V. I. Kulichkov N. P. Kusova A. V. Dyubchenko 《Metallurgist》1989,33(11):224-225
Institute of Ferrous Metallurgy. Novolipetsk Metallurgical Combine. Translated from Metallurg, No. 11, pp. 32–33, November, 1989. 相似文献
999.
1000.
B. V. Dvoskin D. V. Gulyga A. F. Shevchenko N. T. Tkach N. S. Kharchenko V. P. Shkurenko 《Metallurgist》1989,33(4):68-69
Institute of Ferrous Metallurgy. Translated from Metallurg, No. 4, p. 24, April, 1989. 相似文献