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排序方式: 共有147条查询结果,搜索用时 15 毫秒
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Léger B Denicourt-Nowicki A Olivier-Bourbigou H Roucoux A 《Inorganic chemistry》2008,47(19):9090-9096
Rhodium nanoparticles stabilized by 2,2'-, 3,3'-, 4,4'-bipyridine ligands were prepared in various ionic liquids according to a chemical reduction approach. Zerovalent nanospecies in the size range of 2.0-2.5 nm were characterized. The nature of the bipyridine and its influence on the coordination environment of rhodium nanoparticles were investigated in various nonaqueous ionic liquids according to the cation and anion. The hydrogenation of various aromatic compounds by these colloidal suspensions was carried out at 80 degrees C and under 40 bar of H 2. A first structural explanation based on bipyridine coordination modes is proposed to justify the observed different activities. 相似文献
143.
144.
Jean-Pierre Cuif Alexander D Ball Yannicke Dauphin Bastien Farre Julius Nouet Alberto Perez-Huerta Murielle Salomé C Terry Williams 《Microscopy and microanalysis》2008,14(5):405-417
A series of Polynesian pearls has been investigated with particular attention to the structural and compositional patterns of the early developmental stages of the pearl layer. These initial steps in pearl formation bear witness of the metabolic changes that have occurred during the pearl-sac formation. The resulting structurally and biochemically complex structures have been investigated using a variety of techniques that provide us with information concerning both mineral phases and the organic components. Results are discussed with respect to our understanding of the biomineralization mechanisms, as well as for the grafting process. 相似文献
145.
The Cephalotaxus genus belongs to the Cephalotaxaceae family of conifers. Over the past decades it has proved to be a fruitful source of interesting natural products, especially alkaloids (cephalotaxine esters) and terpenoids (abietanes, troponoids), which often display medicinal properties, especially in the anticancer area. Homoharringtonine is active against some orphan leukaemia and is nowadays approaching marketability. A phytochemical update will be provided and the total synthesis of alkaloids and terpenoids will be discussed in detail. 相似文献
146.
Bennès J Alzuaga S Chabé P Morain G Chérioux F Manceau JF Bastien F 《Ultrasonics》2006,44(Z1):e497-e502
Liquids handling is an important issue in biomedical analysis. Two different devices for acoustic manipulation of droplets have already been tested. The first one, more classical, uses a high frequency travelling wave and acoustic streaming. The second one uses low frequency flexural standing waves in a plate. This means of liquid handling is original and easy to implement but the physical principle is not obvious. In order to understand more precisely the phenomena involved we present new observations on droplet displacement between two planes and on the behaviour of a droplet on an inclined vibrating plane with this method. The physical principle involved is discussed. The common acoustic radiation pressure formulation is expressed via the non-linear theory of sound propagation, but in our case the acoustic wavelength is much smaller than the height of a water droplet. To get a better understanding of the phenomenon, further experiments on the internal liquid flow and behaviour of particles in the droplet have been performed. These will be compared with results obtained with particles in a thin water-filled vibrating glass tube. The general conclusion is that the phenomenon is practical to use for droplet displacement even if its complex mechanism is not completely understood. 相似文献
147.
Inside Cover: Hydroxymethylated Dioxobilins in Senescent Arabidopsis thaliana Leaves: Sign of a Puzzling Biosynthetic Intermezzo of Chlorophyll Breakdown (Chem. Eur. J. 33/2015) 下载免费PDF全文