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排序方式: 共有2701条查询结果,搜索用时 15 毫秒
1.
针对某金矿,在回收金银的基础上,对金银浮选尾矿进行云母和长石浮选,以及提纯石英试验,最终获得SiO2品位99.91%的石英产品。提纯石英产品与比利时矽比科矿业有限公司石英产品进行对比试验,通过化学成分、粒度组成、熔制、粘度和热膨胀系数测试对比试验,得出金矿提纯石英达到甚至超过矽比科进口石英产品的各项技术指标。 相似文献
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《International Journal of Hydrogen Energy》2020,45(49):26238-26253
The demands for high-purity hydrogen required in fuel-cell applications impose new goals and challenges for design of well performing water-gas shift (WGS) catalysts. Gold-based catalysts have exhibited high activity in the WGS reaction at low temperature. Preparation of appropriate and economically viable supports with complex composition by various synthesis procedures is an attractive approach to WGS performance improvement. The effect of two different preparation methods (wet impregnation or mechanical mixing) and ceria content (10, 20 or 30 wt%) on textural, structural, surface and reductive properties and WGS activity of gold catalysts was studied. Additionally, the role of Y2O3 as a promoter of ceria was examined. Long-term stability test was carried out at 260 °C over the most active catalyst. The composition of the best performing sample (composed of about 70 wt% alumina), prepared by mechanical mixing, was considered promising in case of practical applications because of its cost efficiency. The combination of gold nanoparticles and alumina supported Y-doped ceria proved an advantageous approach for developing new catalytic formulations with high effectiveness in clean hydrogen production. 相似文献
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X.W. Lou C. Yuan E. Rhoades Q. Zhang L.A. Archer 《Advanced functional materials》2006,16(13):1679-1684
We report a general template strategy for rational fabrication of a new class of nanostructured materials consisting of multicore shell particles. Our approach is demonstrated by encapsulating Au or Pt nanoparticles in silica shells. Other superstructures of these hollow shells, like dimers, trimers, and tetramers can also be formed by nanoparticle‐mediated self‐assembly. We have also used the as‐prepared multicore Au–silica hollow particles to perform the first studies of Ostwald ripening in confined microspace, in which chloride was found to be an efficient mediating ligand. After treatment with aqua regia, Au–Cl complex is formed inside the shell, and is found to be very active under in situ transmission electron microscopy observations while confined in a microcell. This aspect of the work is expected to motivate further in situ studies of confined crystal growth. 相似文献
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L. Sheeney‐Haj‐Ichia S. Pogorelova Y. Gofer I. Willner 《Advanced functional materials》2004,14(5):416-424
Three different configurations of Au‐nanoparticle/CdS‐nanoparticle arrays are organized on Au/quartz electrodes for enhanced photocurrent generation. In one configuration, Au‐nanoparticles are covalently linked to the electrode and the CdS‐nanoparticles are covalently linked to the bare Au‐nanoparticle assembly. The resulting photocurrent, φ = 7.5 %, is ca. 9‐fold higher than the photocurrent originating from a CdS‐nanoparticle layer that lacks the Au‐nanoparticles, φ = 0.8 %. The enhanced photocurrent in the Au/CdS nanoparticle array is attributed to effective charge separation of the electron–hole pair by the injection of conduction‐band electrons from the CdS‐ to the Au‐nanoparticles. Two other configurations involving electrostatically stabilized bipyridinium‐crosslinked Au/CdS or CdS/Au nanoparticle arrays were assembled on the Au/quartz crystal. The photocurrent quantum yields in the two systems are φ = 10 % and φ = 5 %, respectively. The photocurrents in control systems that include electrostatically bridged Au/CdS or CdS/Au nanoparticles by oligocationic units that lack electron‐acceptor units are substantially lower than the values observed in the analogous bipyridinium‐bridged systems. The enhanced photocurrents in the bipyridinium‐crosslinked systems is attributed to the stepwise electron transfer of conduction‐band electrons to the Au‐nanoparticles by the bipyridinium relay bridge, a process that stabilizes the electron–hole pair against recombination and leads to effective charge separation. 相似文献
6.
V. Morandi F. Marabelli V. Amendola M. Meneghetti D. Comoretto 《Advanced functional materials》2007,17(15):2779-2786
Polystyrene artificial opals with few gold nanoparticles (AuNp) embedded in the interstices (doping) are grown by using the meniscus technique starting from a mixed suspension of microspheres and AuNp. Samples having different sphere diameters and nanoparticle loads have been prepared. Their reflectance spectra clearly show a dramatic bathochromic shift of the photonic stop band (up to 1400 cm–1) and a reduction of its full width half maximum, due to an increase of the effective refractive index of about 8 % with respect to bare opals, which is accounted for by analytical theoretical models. Reflectance spectra do not show any direct evidence of AuNp absorption even at the higher AuNp doping level. Nanosecond transient absorption measurements on these systems indicate that a variation of transmission (optical switching) of about 150 % is observed for AuNp doped opals upon photoexcitation with 9 ns laser pulses at 532 nm. No switching is instead observed for bare opals. 相似文献
7.
No authorship indicated 《Canadian Metallurgical Quarterly》2003,58(8):554
Presents the 2003 American Psychological Foundation's Gold Medal Award for Life Achievement in the Science of Psychology, which was presented to Robert Rosenthal. A biography of Rosenthal is provided, along with a selected bibliography and the text of the award citation: "For outstanding scientific contributions that have had a profound influence on research methods, empirical investigations, theory, and applications. Robert Rosenthal's seminal research on interpersonal expectancy inspired hundreds of studies with applications within and beyond psychology. His amplification of experimenter- and subject-related artifacts and his insights about ethical issues have improved the way that research is conducted. His statistical contributions are classic and wide ranging, including his body of work on meta-analysis and contrast analysis and his formulation of valuable procedures, such as the binomial effect-size display and counternull statistics. An exceptional scientist, teacher, mentor, and author, Rosenthal, with his generous and brilliant touch, has shaped the lives and work of countless others." (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
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No authorship indicated 《Canadian Metallurgical Quarterly》2007,62(5):388
Announces the 2007 recipient of the Gold Medal Award for Life Achievement in the Practice of Psychology: Patricia M. Bricklin. A brief biography, highlighting areas of special focus in Bricklin's work, is provided. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
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No authorship indicated 《Canadian Metallurgical Quarterly》2007,62(5):391
Announces the 2007 recipient of the Gold Medal Award for Life Achievement in the Psychology in the Public Interest: Rhoda K. Unger. A brief biography, highlighting areas of special focus in Unger's work, is provided. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献