全文获取类型
收费全文 | 670篇 |
免费 | 4篇 |
国内免费 | 12篇 |
专业分类
电工技术 | 3篇 |
综合类 | 5篇 |
化学工业 | 258篇 |
金属工艺 | 8篇 |
机械仪表 | 4篇 |
建筑科学 | 8篇 |
矿业工程 | 4篇 |
能源动力 | 220篇 |
轻工业 | 2篇 |
水利工程 | 2篇 |
石油天然气 | 6篇 |
无线电 | 28篇 |
一般工业技术 | 129篇 |
冶金工业 | 7篇 |
自动化技术 | 2篇 |
出版年
2024年 | 3篇 |
2023年 | 20篇 |
2022年 | 59篇 |
2021年 | 45篇 |
2020年 | 46篇 |
2019年 | 49篇 |
2018年 | 30篇 |
2017年 | 29篇 |
2016年 | 21篇 |
2015年 | 18篇 |
2014年 | 48篇 |
2013年 | 38篇 |
2012年 | 22篇 |
2011年 | 42篇 |
2010年 | 30篇 |
2009年 | 37篇 |
2008年 | 36篇 |
2007年 | 26篇 |
2006年 | 25篇 |
2005年 | 8篇 |
2004年 | 11篇 |
2003年 | 14篇 |
2002年 | 6篇 |
2001年 | 9篇 |
2000年 | 3篇 |
1999年 | 3篇 |
1998年 | 4篇 |
1997年 | 3篇 |
1990年 | 1篇 |
排序方式: 共有686条查询结果,搜索用时 31 毫秒
41.
Sang Soo Lee Hyun Jong Kim Kyung Taek Jung Hak Soo Kim Yong Gun Shul 《Korean Journal of Chemical Engineering》2001,18(6):914-918
Iron or tungsten-doped nano TiO2 were successfully synthesized from TiCl4. All of the samples showed anatase phase of TiO2. For the iron-doped TiO2, Iron ion was well dispersed in the TiO2 lattice. However, tungsten-doped TiO2 formed 12-tungstate with anatase TiO2. As the concentration of tungsten increased, 12-tungstate disappeared. The photocatalytic oxidation of acetaldehyde was evaluated
to examine the photocatalytic characteristics of metal-doped TiO2. Because of the surface containing metal oxide or metal precursors at high concentration metal ion, increasing the concentration
of W or Fe ion decreased the reactivity. The reaction rate was drastically increased after 300 °C heat treatment. Furthermore,
the photocatalytic activity of iron- or tungsten-doped TiO2 was higher than that of synthesized pure TiO2 and commercial TiO2. 相似文献
42.
Jindo Kim Dong Won Hwang Sang Won Bae Young Gul Kim Jae Sung Lee 《Korean Journal of Chemical Engineering》2001,18(6):941-947
A [110] layered perovskite, La2Ti2O7, was a good photocatalyst under ultraviolet light in water splitting reaction. The material was synthesized with La2O3 and TiO2 as precursors by solid-state transformation. The morphology and photocatalytic activity of La2Ti2O7 depended on the preparation methods, as well as purity and morphology of the precursors. Wet-grinding of precursors in ethanol
gave a product with higher crystallinity and phase purity, and thus higher photocatalytic activity, than dry-grinding without
solvent. It was important to reduce the particle size of La2O3, as it usually had larger initial particle sizes than TiO2. Thus, the particle size of La2O3 had a strong effect on the crystallinity and surface area of the product La2Ti2O7. On the other hand, a severe chemical purity control was required for TiO2, while the effect of morphology was relatively small. In all cases, a high degree of crystallinity and purity of the prepared
La2Ti2O7 was critical to show a high photocatalytic water-splitting activity. 相似文献
43.
A new type of visible-light-driven photocatalyst BaCo0.5Nb0.5O3 was successfully synthesized via a sol-gel process in this study. After heating the precursors at 1000 °C, a pure perovskite phase was obtained. The particle size and crystallinity of BaCo0.5Nb0.5O3 powders markedly increased with a rise in the calcination temperature. The band gap of BaCo0.5Nb0.5O3 calculated from the UV-visible spectra was found to be less than that of titania. BaCo0.5Nb0.5O3 was demonstrated to have photocatalytic activity under visible light irradiation and this activity significantly depended on the synthesis temperature. The sol-gel derived powders were found to have better photocatalytic activity than the solid-state derived powders because of the reduced particle size and increased surface area. 相似文献
44.
CdS/石墨烯纳米复合材料是一种重要的半导体光催化剂,在可见光下具有很好的催化活性。本文重点介绍了CdS/石墨烯纳米复合材料的制备方法及性能影响因素,并分析了几种常用制备方法的特点及运用效果。本文还介绍了CdS/石墨烯纳米复合材料近年来的应用研究,并对其应用的发展趋势做出了展望。 相似文献
45.
Caolong Li Jian YuanBingyan Han Wenfeng Shangguan 《International Journal of Hydrogen Energy》2011,36(7):4271-4279
Novel CdS nanomaterials were synthesized by a simple “one-pot” hydrothermal biomolecule-assisted method using glutathione (GSH) as the sulfur source and structure-directing reagent. Various morphologies of CdS photocatalysts, such as solid nanospheres (s-CdS), hollow nanospheres (h-CdS) and nanorods (r-CdS), were obtained by controlling only the hydrothermal temperatures. The X-ray diffraction patterns confirmed that all of the samples were typical hexagonal wurtzite CdS. It was found that the absorption edge of s-CdS was at 465 nm with a greater blue shift compared to that of h-CdS and r-CdS. The photocatalytic activity of s-CdS was superior to that of h-CdS and r-CdS under visible light. Photoluminescence measurements revealed their different photogenerated electron/hole recombination ability, which was in accordance with the order of s-CdS < h-CdS < r-CdS. The excellent photocatalytic activity of s-CdS was ascribed to the small sizes of sub-nanocrystallites, which make it easy for photoinduced electrons and holes on the solid sphere to migrate to the surface and react with water and the sacrificial agent quickly. It was crucial to control the temperature for preparing CdS photocatalysts via hydrothermal methods. The formation mechanism of different morphology might be due to complexation, S-C bond rupture, spherical aggregation and Ostwald ripening processes. 相似文献
46.
Yang Liu Lei Xie Yan Li Rong Yang Jianglan Qu Yaoqi Li Xingguo Li 《Journal of power sources》2008,183(2):701-707
Cubic SrTiO3 powders were synthesized by three methods: the polymerized complex (PC) method, the solid state reaction, and the milling assistant method. The samples obtained were characterized by X-ray diffraction (XRD), UV–vis spectroscopy (UV–vis), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The mean diameters of the as-synthesized SrTiO3 particles were 30 nm by the polymerized complex method, 140 nm by the solid state reaction, and 30 nm by the milling assistant method. The photocatalytic activity of hydrogen evolution from water splitting over SrTiO3 powders by the polymerized complex method is higher than that by the solid state reaction and the milling assistant method. Particle size, uniformity of components, and particle aggregation extent affect the photocatalytic activity of SrTiO3 for hydrogen evolution. The best rate of photocatalytic hydrogen evolution over SrTiO3 by the polymerized complex method under UV illumination is as high as 3.2 mmol h−1 g−1. 相似文献
47.
Hiromi Yamashita Yo Fujii Yuichi Ichihashi Shu Gou Zhang Keita Ikeue Dal Ryung Park Keiko Koyano Takashi Tatsumi Masakazu Anpo 《Catalysis Today》1998,45(1-4):221-227
Highly dispersed titanium oxide catalysts have been prepared within zeolite cavities as well as in the zeolite framework and utilized as photocatalysts for the reduction of CO2 with H2O to produce CH4 and CH3OH at 328 K. In situ photoluminescence, ESR, diffuse reflectance absorption and XAFS investigations indicate that the titanium oxide species are highly dispersed within the zeolite cavities and framework and exist in tetrahedral coordination. The charge transfer excited state of the highly dispersed titanium oxide species play a significant role in the reduction of CO2 with H2O with a high selectivity for the formation of CH3OH, while the catalysts involving the aggregated octahedrally coordinated titanium oxide species show a high selectivity to produce CH4, being similar to reactions on the powdered TiO2 catalysts. Ti-mesoporous molecular sieves exhibit high photocatalytic reactivity for the formation of CH3OH, its reactivity being much higher than the powdered TiO2 catalysts. The addition of Pt onto the highly dispersed titanium oxide catalysts promotes the charge separation which leads to an increase in the formation of CH4 in place of CH3OH formation. 相似文献
48.
Xiaohong S. Li Glen E. Fryxell Chongmin Wang Mark H. Engelhard 《Microporous and mesoporous materials》2008,111(1-3):639-642
Ag-doped mesoporous titanium oxide was prepared using non-ionic surfactants and easily handled titanium precursors, under mild reaction conditions. The structure of these materials was determined as a function of the concentration of the Ag dopant and calcination temperature. In contrast to the stabilizing effect of Cd-doping on mesoporous TiO2, Ag doping was found to significantly destabilize the mesoporous structure. 相似文献
49.
Sergio M. Bonesi Esther Carbonell Hermenegildo Garcia Maurizio Fagnoni Angelo Albini 《Applied catalysis. B, Environmental》2008,79(4):368-375
Solid photocatalysts in which the 2,4,6-triphenylpyrylium (TP) or 2,4,6-triphenylthiapyrylium cation (TTP) are encapsulated within zeolite Y or deposited on mesoporous silica are used as photosensitizers for the oxidation of sulfides, both aromatic and aliphatic, in solvents of various polarity. Contrary to the same cations in solution, these solid sensitizers are not significantly degraded during operation. An effective oxygenation takes place leading to sulfoxides, disulfides, sulfinic and sulfenic esters as well as sulfonic acids. This large scope method shows a limited dependence on the substrate structure and on conditions and is suitable for the abatement of sulfur-containing pollutants. 相似文献
50.
采用TiO_2光催化剂的空气清新纺织品 总被引:1,自引:0,他引:1
介绍了一种新型的空气清新剂TiO2 光催化剂的反应原理 ,并探讨了其在纺织领域中的应用和存在问题 ,提出了解决方法等 相似文献