全文获取类型
收费全文 | 1365篇 |
免费 | 68篇 |
国内免费 | 5篇 |
专业分类
电工技术 | 14篇 |
综合类 | 3篇 |
化学工业 | 302篇 |
金属工艺 | 47篇 |
机械仪表 | 61篇 |
建筑科学 | 71篇 |
矿业工程 | 2篇 |
能源动力 | 175篇 |
轻工业 | 180篇 |
水利工程 | 6篇 |
石油天然气 | 2篇 |
无线电 | 106篇 |
一般工业技术 | 219篇 |
冶金工业 | 50篇 |
原子能技术 | 6篇 |
自动化技术 | 194篇 |
出版年
2024年 | 8篇 |
2023年 | 14篇 |
2022年 | 27篇 |
2021年 | 47篇 |
2020年 | 49篇 |
2019年 | 61篇 |
2018年 | 54篇 |
2017年 | 58篇 |
2016年 | 60篇 |
2015年 | 46篇 |
2014年 | 56篇 |
2013年 | 125篇 |
2012年 | 76篇 |
2011年 | 108篇 |
2010年 | 80篇 |
2009年 | 107篇 |
2008年 | 97篇 |
2007年 | 72篇 |
2006年 | 49篇 |
2005年 | 42篇 |
2004年 | 17篇 |
2003年 | 24篇 |
2002年 | 25篇 |
2001年 | 21篇 |
2000年 | 19篇 |
1999年 | 17篇 |
1998年 | 18篇 |
1997年 | 8篇 |
1996年 | 7篇 |
1995年 | 5篇 |
1994年 | 8篇 |
1993年 | 1篇 |
1992年 | 3篇 |
1991年 | 5篇 |
1990年 | 3篇 |
1989年 | 4篇 |
1988年 | 3篇 |
1987年 | 1篇 |
1986年 | 2篇 |
1985年 | 1篇 |
1984年 | 2篇 |
1983年 | 3篇 |
1982年 | 1篇 |
1978年 | 2篇 |
1974年 | 1篇 |
1956年 | 1篇 |
排序方式: 共有1438条查询结果,搜索用时 8 毫秒
1.
This paper presents the mass transfer results from an impinging liquid jet to a rotating disk. The mass transfer coefficients were measured using the electrochemical limiting diffusion current technique (ELDCT). Rotational Reynolds number (Rer) in the range of 3.4 × 104–1.2 × 105, jet Reynolds number (Rej) 1.7 × 104–5.3 × 104 and non-dimensional jet-to-disk spacing (H/d) 2–8 were taken into consideration as parameters. It was found that the jet impingement resulted in a substantial enhancement in the mass transfer compared to the case of the rotating disk without jet. 相似文献
2.
Metin Kul Muhsin Zor Ahmet Senol Aybek Sinan Irmak Evren Turan 《Solar Energy Materials & Solar Cells》2007,91(10):882-887
The CdO:F samples have been deposited onto microscope glass substrates at 250 °C by ultrasonic spray pyrolysis method. With the incorporation of fluorine into CdO, the direct optical transition has shifted towards the shorter wavelengths, and the transparency of the material has increased at a given wavelength above the fundamental absorption edge. The shift in the absorption edge is explained by means of the Moss–Burstein effect, which is also supported with the results of the current–voltage characteristics. Here, a correlation has been established between the band broadening and the increase in conductivity due to the increase in carrier density. 相似文献
3.
Nilgün Kzlcan Belks Ustamehmetolu Nesrin
z A. Sezai Sara Ahmet Akar 《应用聚合物科学杂志》2003,89(11):2896-2901
Soluble and processable conductive copolymers of silicone tegomers and pyrrole were developed. This was easily accomplished by the oxidative polymerization of pyrrole monomer by Ce(IV) salt in the presence of silicone tegomers with hydroxyl chain ends. The resulting copolymers were soluble in dimethylformamide. The products were characterized by Fourier transform infrared, 1H‐NMR, and four‐point probe conductivity, and their surface properties were investigated with contact‐angle measurements. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2896–2901, 2003 相似文献
4.
5.
Thermodynamic analysis of solar photovoltaic cell systems 总被引:1,自引:0,他引:1
Ahmet Duran Sahin Ibrahim Dincer Marc A. Rosen 《Solar Energy Materials & Solar Cells》2007,91(2-3):153-159
The thermodynamic characteristics of solar photovoltaic (PV) cells are investigated from a perspective based on exergy. A new efficiency is developed that is useful in studying PV performance and possible improvements. Exergy analysis is applied to a PV system and its components, and exergy flows, losses and efficiencies are evaluated. Energy efficiency is seen to vary between 7% and 12% during the day. In contrast, exergy efficiencies, which incorporate the second law of thermodynamics and account for solar irradiation exergy values, are lower for electricity generation using the considered PV system, ranging from 2% to 8%. Values of “fill factors” are determined for the system and observed to be similar to values of exergy efficiency. 相似文献
6.
Liquid holdup and wetting efficiency in packed columns were determined using a tracer method. A new model was developed considering axial dispersion, and analysis was made using the moment technique. The saturated solution of KG was used as an inert tracer and total liquid holdups were determined in the first part of experiments. As an adsorbable tracer, dioxane was utilized in the second part of the work and wetting efficiencies were obtained. Adsorption equilibrium constant was determined by the experiments conducted in a liquid full bed. A model proposed between liquid holdup and wetting efficiency gave good agreement with the experimental results. Axial dispersion effects were also taken into account during the work. It was also shown that axial dispersion of liquid phase should be considered especially in the small scale trickle bed reactors. @KEYWORDS:Packed beds,Wetting efficiency,Liquid holdup,Tracer method,Moment technique,Trickle bed reactors. 相似文献
7.
Ahmet Ekmekyapar Nizamettin Demirkran Asm Künkül 《Chemical Engineering Research and Design》2008,86(9):1011-1016
Ulexite is an important boron mineral used for the production of boron compounds. The aims of this study are to examine the dissolution kinetics of ulexite in acetic acid solutions, and to present an alternative process to produce boric acid. In order to investigate the dissolution kinetics of ulexite in acetic acid solutions, the concentration of solution, reaction temperature, solid-to-liquid ratio, and particle size were selected as experimental parameters. It was determined that the dissolution rate of ulexite increased with increasing solution concentration and temperature and decreasing particle size and solid-to-liquid ratio. The activation energy of the process was found to be 55.8 kJ/mol. 相似文献
8.
Diels-Alder cycloaddition of furfural to C60 in toluene has been realised. UV-VIS, FTIR and 1H-NMR investigations suggest that the conjugated structure of furfural was changed into a non-conjugated structure in the product. 相似文献
9.
10.
The Journal of Supercomputing - Data warehouses are very large databases and play key role in intelligent decision making in enterprises. The bitmap join indexes selection problem is crucial in the... 相似文献