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121.
122.
Efficient Microwave‐assisted One‐pot Synthesis of Novel Spironaphthopyrano‐one Derivatives 下载免费PDF全文
Rapid and efficient one‐pot three‐component synthesis of new spironaphthopyrano‐one derivatives by cyclocondensation reaction in aqueous media is achieved under microwave irradiation conditions. This protocol has the advantages of higher yield, lower cost, reduced time, environmental impact, and convenient procedure. 相似文献
123.
In this paper we review some of the recently introduced hypertopologies on collections of nonempty closed subsets of a metrizable space in the context of continuity properties of the prox map and the restricted center map. We identify here suitable families A, B of nonempty closed sets equipped with natural topologies, as coordinate spaces for the gap functional and the restricted radius functional, with a view to explore bivariate continuity of these functionals. This leads us to sharpenings of many known results as well as to some new results for upper semicontinuity of the prox map and the restricted center map. This, in turn, also leads us to improvements of certain best approximation results for convex-valued multifunctions and fixed point theorems for such multifunctions. 相似文献
124.
S. Mahendra Kumar Parag A. Deshpande M. Krishna M. S. Krupashankara Giridhar Madras 《Plasma Chemistry and Plasma Processing》2010,30(4):461-470
Nanocrystalline TiO2 was synthesized using the microwave plasma technique and characterized using X-ray diffraction, transmission electron microscopy, scanning electron microscopy, laser particle size analyzer, UV–vis spectroscopy and BET surface area analyzer. The synthesized TiO2 powder crystallized in anatase phase and the crystallite sizes were in nanometers. The photocatalytic activity of the compound was determined and compared against the activity of the commercial Degussa P-25 TiO2 catalyst. The degradation rates of the dyes were found to be higher over the synthesized TiO2 as compared to that over commercial Degussa P-25 TiO2. 相似文献
125.
For long duration steady state operation of SST1, it would be very crucial to maintain the plasma radial and vertical positions
accurately. For designing the position controller in SST1 we have adopted the simple linear RZIP control model. While the
vertical position instability is slowed down by a set of passive stabilizers placed closed to the plasma edge, a pair of in-vessel
active feedback coils can adequately control vertical position perturbations of up to 1 cm. The shifts in radial position
arising due to minor disruptions would be controlled by a separate pair of poloidal field (PF) coils also placed inside the
vessel, however the controller would ignore fast but insignificant changes in radius arising due to edge localised modes.
The parameters of both vertical and radial position control coils and their power supplies are determined based on the RZIP
simulations. 相似文献
126.
Suvarna S. Deshpande 《Tetrahedron》2005,61(33):8025-8030
This is the first exhaustive report on the variation of stereoselectivity ratios for a simple Diels-Alder reaction between cyclopentadiene and methyl acrylate. The reaction was carried out in aqueous mixtures of methanol, ethanol, propan-1-ol and butan-1-ol in presence of LiClO4, LiCl, NaCl, KCl, CaCl2 and MgCl2. The endo stereoisomer decreases with the increase in carbon chain length of the alcohol. However, LiClO4, a salting-in agent in water becomes salting-out in aqueous mixtures of alcohols. The solvent properties, thus can be attuned by adjusting the amount of solvents and salts. 相似文献
127.
Summary An XRF method for the determination of Y, Ce, Pr, Nd, Eu and Gd in high purity samarium oxide is described. Samples in oxalate form are mixed with boric acid in the ratio 31. About 800 mg of the mixture is pressed as a double layer pellet. Experimental parameters are selected to give maximum peak to noise ratio. The analysis lines are chosen after studying line interferences. The estimation limit ranges from 0.005% to 1% for most elements.
Röntgenfluorescenzanalyse von Y, Ce, Pr, Nd, Eu und Gd in Samariumoxid hoher Reinheit
Zusammenfassung Zur röntgenanalytischen Bestimmung von Spuren Seltener Erden in hochreinem Samariumoxid wird die Probe in die Oxalatform übergeführt, mit Borsäure im Verhältnis 31 gemischt und zu je 800 mg in Doppelschichttabletten (über Borsäure) gepreßt. Für ein maximales Peak/Untergrund-Verhältnis wurden die experimentellen Parameter entsprechend ausgewählt. Die benutzten Analysenlinien ergaben sich aus einer Untersuchung der Störungen. Die Erfassungsgrenze liegt zwischen 0,005% und 1%.相似文献
128.
129.
K. Avasthi M.N. Deshpande Wen-Ching Han J.M. Cook U. Weiss 《Tetrahedron letters》1981,22(36):3475-3478
The influence of steric factors on the synthesis of substituted bicyclo[3.3.0]octane-3,7 diones the condensation of 1,2-dicarbonyl compounds with dimethyl 3-ketoglutarate is described. 相似文献
130.
Summary An XRF method for the determination of Eu, Gd, Tb, Dy, Ho, Er and Yb in yttrium oxide has been developed. The samples are converted to yttrium oxalate and presented to the spectrometer in the form of pressed pellets. Philips PW-1220, semiautomatic X-ray spectrometer is used for analysis. Analysis lines have been chosen after careful study of line interferences. The lower estimation limit for Yb is 0.01% and for other elements it is 0.005%. The method has been tested for its accuracy by analysing synthetic samples with known composition.
Bestimmung von häufig vorkommenden Verunreinigungen an Seltenen Erden in Yttriumoxid hoher Reinheit mit Hilfe der Röntgenfluorescenzanalyse
Zusammenfassung Ein Verfahren zur röntgenfluorescenzanalytischen Bestimmung von Eu, Gd, Tb, Dy, Ho, Er und Yb in Yttriumoxid wurde ausgearbeitet. Die Probe wird zu Yttriumoxalat umgesetzt und in Form von Preßtabletten der RFA unterworfen. Das halbautomatische Röntgenfluorescenz-Spektrometer Philips PW-1220 wurde verwendet. Eine sorgfältige Untersuchung der Interferenzen führte zur Wahl der Analysenlinien. Die untere Bestimmungsgrenze liegt für Yb bei 0,01%, für die anderen Elemente bei 0,005%. Die Zuverlässigkeit des Verfahrens wurde anhand von synthetischen Proben bekannter Zusammensetzung geprüft.相似文献