全文获取类型
收费全文 | 11595篇 |
免费 | 831篇 |
国内免费 | 243篇 |
专业分类
电工技术 | 300篇 |
综合类 | 757篇 |
化学工业 | 5547篇 |
金属工艺 | 496篇 |
机械仪表 | 136篇 |
建筑科学 | 2462篇 |
矿业工程 | 119篇 |
能源动力 | 50篇 |
轻工业 | 163篇 |
水利工程 | 225篇 |
石油天然气 | 190篇 |
武器工业 | 64篇 |
无线电 | 151篇 |
一般工业技术 | 1763篇 |
冶金工业 | 195篇 |
原子能技术 | 25篇 |
自动化技术 | 26篇 |
出版年
2024年 | 77篇 |
2023年 | 146篇 |
2022年 | 235篇 |
2021年 | 298篇 |
2020年 | 281篇 |
2019年 | 229篇 |
2018年 | 246篇 |
2017年 | 335篇 |
2016年 | 333篇 |
2015年 | 398篇 |
2014年 | 619篇 |
2013年 | 660篇 |
2012年 | 925篇 |
2011年 | 873篇 |
2010年 | 640篇 |
2009年 | 754篇 |
2008年 | 615篇 |
2007年 | 818篇 |
2006年 | 761篇 |
2005年 | 634篇 |
2004年 | 470篇 |
2003年 | 396篇 |
2002年 | 340篇 |
2001年 | 265篇 |
2000年 | 240篇 |
1999年 | 229篇 |
1998年 | 182篇 |
1997年 | 125篇 |
1996年 | 105篇 |
1995年 | 47篇 |
1994年 | 72篇 |
1993年 | 71篇 |
1992年 | 58篇 |
1991年 | 29篇 |
1990年 | 23篇 |
1989年 | 31篇 |
1988年 | 16篇 |
1987年 | 24篇 |
1986年 | 14篇 |
1985年 | 12篇 |
1984年 | 6篇 |
1983年 | 7篇 |
1982年 | 22篇 |
1981年 | 2篇 |
1980年 | 3篇 |
1977年 | 2篇 |
1951年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
41.
采用脂环族环氧树脂、柔韧性环氧树脂、改性脂环胺类固化剂为主要原料,研制出户外像素管灌注软胶,产品具有耐紫外线辐照、耐冷热冲击、粘接性好等特点。介绍其制备方法、性能及用。 相似文献
42.
四官能环氧树脂的合成以及在覆铜板中的应用 总被引:1,自引:0,他引:1
对四官能环氧树脂[1,1,2,2-四(对羟基苯基)乙烷四缩水甘油醚]的合成与改性及在覆铜板中的应用作了初步探讨,并对其屏蔽紫外线与产生荧光的机理作用作了简单阐述。 相似文献
43.
44.
Zinc Coated Steel/Epoxy Adhesive Systems: Investigation of the Interfacial Zone by FTIR Spectroscopy
The present study takes advantage of the ability of Fourier Transform Infrared Spectroscopy (FTIR) for the analysis of ultrathin organic films on metals. FTIR in the reflection mode (IRRAS) is used in order to study the interaction of ultrathin films of dicyandiamide (hardener of most one-pack epoxy resins) with various substrates, model ones such as gold or zinc and industrial ones such as steel and zinc-coated steels.
Pure zinc surfaces and, to a lesser extent, zinc-coated steels are shown to react with dicyandiamide after heating at 180°C, as evidenced by the frequency shift of the absorption band (at about 2200 cm-1) characteristic for nitrile groups. As real systems consist of thick layers of a fully formulated adhesive cured onto a metallic substrate, the direct investigation of such a buried interphase is no longer possible by FTIR and by most of the known spectroscopies. Some mechanically tested specimens are then analysed, after failure, by FTIR microspectrometry. The spectra obtained, corresponding to the fracture initiation zone which is about 100 μm in diameter, advocate for the presence of an ultrathin layer of modified polymer still covering the substrate. 相似文献
Pure zinc surfaces and, to a lesser extent, zinc-coated steels are shown to react with dicyandiamide after heating at 180°C, as evidenced by the frequency shift of the absorption band (at about 2200 cm-1) characteristic for nitrile groups. As real systems consist of thick layers of a fully formulated adhesive cured onto a metallic substrate, the direct investigation of such a buried interphase is no longer possible by FTIR and by most of the known spectroscopies. Some mechanically tested specimens are then analysed, after failure, by FTIR microspectrometry. The spectra obtained, corresponding to the fracture initiation zone which is about 100 μm in diameter, advocate for the presence of an ultrathin layer of modified polymer still covering the substrate. 相似文献
45.
46.
47.
48.
Xiaohong Gu Tinh Nguyen Mounira Oudina David Martin Bouchra Kidah Joan Jasmin Aziz Rezig Lipiin Sung Eric Byrd Jonathan W. Martin Derek L. Ho Y. C. Jean 《Journal of Coatings Technology and Research》2005,2(7):547-556
Atomic force microscopy (AFM) has been used to study the morphology and microstructure of an amine-cured epoxy before and
after outdoor exposure. Measurements were made from samples prepared in an essentially CO2-free, H2O-free glove box and from samples prepared in ambient conditions. For those prepared in a CO2-free glove box, AFM imaging was conducted on (1) an unexposed air/coating surface, (2) an unexposed coating bulk, (3) an
unexposed coating/substrate interface, and (4) a field exposed air/coating surface. For samples prepared in ambient conditions,
only the unexposed air/coating surface was investigated. The same regions of the exposed samples were scanned periodically
by the AFM to monitor changes in the surface morphology of the coating as UV exposure progressed. Small angle neutron scattering
and Fourier transform infrared spectroscopy (FTIR) studies were performed to verify the microstructure and to follow chemical
changes during outdoor exposure, respectively. The results have shown that amine blushing, which occurs only under ambient
conditions, had a significant effect on the surface morphology and microstructure of the epoxy. The surface morphology of
the samples prepared under CO2-free, dry conditions was generally smooth and homogeneous. However, the interface and the bulk samples clearly revealed a
two-phase structure consisting of bright nodular domains and dark interstitial regions, indicating an inhomogeneous microstructure.
Such heterogeneous structure of the bulk was in good agreement with results obtained by small angle neutron scattering of
unexposed samples and by AFM phase imaging of the degraded sample surface. The relationship between submicrometer physical
changes and molecular chemical degradation is discussed.
Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, October 27–29, 2004, in Chicago,
IL. 相似文献
49.
在环氧-聚酰胺体系中分别加入“海岛结构”QS-1、聚硫橡胶、液体丁腈橡胶增韧改性,通过对固化物剪切强度、弯曲弹性模量及断裂强度的对比,“海岛结构”QS-1增韧综合性能较好. 相似文献
50.
In this paper we describe an apparatus for reproducibly measuring thermal shock resistance of thick polymer layers bonded to metals. The thermal shock behavior is discussed in terms of epoxy samples bonded to an aluminum substrate. It was found that both high resin toughness and low resin thermal expansion coefficient improved thermal shock resistance of thick coatings, but only a sample containing 60wt. % glass beads did not develop a failure crack. Effects of sample thickness, temperature gradient, and resin composition on thermal shock behavior are discussed. 相似文献