全文获取类型
收费全文 | 332篇 |
免费 | 13篇 |
专业分类
电工技术 | 5篇 |
综合类 | 1篇 |
化学工业 | 48篇 |
金属工艺 | 14篇 |
机械仪表 | 5篇 |
建筑科学 | 25篇 |
能源动力 | 3篇 |
轻工业 | 25篇 |
水利工程 | 1篇 |
无线电 | 25篇 |
一般工业技术 | 74篇 |
冶金工业 | 80篇 |
原子能技术 | 7篇 |
自动化技术 | 32篇 |
出版年
2022年 | 6篇 |
2020年 | 3篇 |
2019年 | 4篇 |
2018年 | 8篇 |
2017年 | 4篇 |
2016年 | 5篇 |
2015年 | 4篇 |
2014年 | 8篇 |
2013年 | 14篇 |
2012年 | 5篇 |
2011年 | 19篇 |
2010年 | 11篇 |
2009年 | 14篇 |
2008年 | 14篇 |
2007年 | 18篇 |
2006年 | 14篇 |
2005年 | 13篇 |
2004年 | 7篇 |
2003年 | 12篇 |
2002年 | 9篇 |
2001年 | 11篇 |
2000年 | 8篇 |
1999年 | 4篇 |
1998年 | 22篇 |
1997年 | 15篇 |
1996年 | 10篇 |
1995年 | 4篇 |
1994年 | 7篇 |
1993年 | 7篇 |
1990年 | 2篇 |
1989年 | 8篇 |
1987年 | 2篇 |
1984年 | 2篇 |
1983年 | 4篇 |
1982年 | 2篇 |
1981年 | 3篇 |
1978年 | 2篇 |
1977年 | 3篇 |
1976年 | 5篇 |
1975年 | 3篇 |
1974年 | 4篇 |
1973年 | 3篇 |
1971年 | 4篇 |
1969年 | 4篇 |
1968年 | 1篇 |
1966年 | 1篇 |
1964年 | 1篇 |
1958年 | 1篇 |
1957年 | 1篇 |
1955年 | 1篇 |
排序方式: 共有345条查询结果,搜索用时 0 毫秒
341.
342.
B. Krause M. Ritschel Ch. Täschner S. Oswald W. Gruner A. Leonhardt P. Pötschke 《Composites Science and Technology》2010
The electrical percolation behaviour of five different kinds of carbon nanotubes (CNTs) synthesised by two CVD techniques was investigated on melt mixed composites based on an insulating polyamide 6.6 matrix. The electrical percolation behaviour was found to be strongly dependent on the properties of CNTs which varied with the synthesis conditions. The lowest electrical percolation threshold (0.04 wt.%) was determined for as grown multi-walled carbon nanotubes without any purification or chemical treatment. Such carbon nanotubes were synthesised by the aerosol method using acetonitrile as ferrocene containing solvent and show relatively low oxygen content near the surface, high aspect ratio, and good dispersability. Similar properties could be found for nanotubes produced by the aerosol method using cyclohexane, whereas CNTs produced by the fixed bed method using different iron contents in the catalyst material showed much higher electrical percolation thresholds between 0.35 and 1.02 wt.%. 相似文献
343.
Agnieszka Iwan Patrice Rannou Henryk Janeczek Marcin Palewicz Agnieszka Hreniak Pawel Bilski Frédéric Oswald Damian Pociecha 《Synthetic Metals》2010,160(9-10):859-865
One series of symmetrical azine-type liquid crystals were synthesized and their chemical structure identified by FTIR, NMR, high resolution mass spectrometry-electro spray ionization (MS-ESI) and elemental analysis. The absorption (UV–vis), photoluminescence (PL) and thermoluminescence (TL) features of the compounds are documented. X-ray diffraction was employed to evaluate their phase transitional behaviour. Their mesomorphic properties were investigated by polarizing optical microscopy (POM) and differential scanning calorimetry (DSC). Terminal groups of the liquid crystals had an effect on their mesomorphic properties. Azine with alkoxysemiperfluorinated end-groups (A1) exhibited smectic C (SmC) phase, whereas azine with octadecyloxy end chains (A3) showed SmC and SmA phases. Azine with 5″-octyl-2,2′:5′,2″-terthiophene groups (A2) exhibited only nematic phase. Different types of N and SmC textures were found and investigated by POM technique. Azine with thiophene groups (A2) has an absorption band about 138 nm batochromically shifted compared to the analogous band of other compounds. The lowest optical band gap value (2.34 eV) was detected for A2. Azines emitted violet or green light. The thermoluminescence emission of azines occurred at about 390–440 nm wavelengths. Current–voltage measurements were performed on ITO/compound/Alq3/Al and ITO/TiO2/compound/Alq3/Al devices before and after light irradiation. To prepare TiO2 layer, sol–gel technique was applied. 相似文献
344.
345.