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131.
Michela Gasperini Chiara Remondini Alessandro Caselli Sergio Cenini 《Journal of organometallic chemistry》2005,690(20):4517-4529
The application of the palladium-phenanthroline catalytic system to the carbonylation of nitrobenzene in the presence of aniline to afford diphenylurea has been investigated. The reaction is best performed with equimolar amounts of the two reagents. Use of higher concentrations of either aniline or nitrobenzene or an increase in temperature in the range 120-170 °C leads to the formation of higher amounts of azo- and azoxybenzene. The latter were found to contain exclusively the aryl moiety deriving from nitrobenzene, with no inclusion of that derived from aniline. The addition of a small amount of diphenylphosphinic acid doubles the conversion and improves the selectivity in diphenylurea, but the effect is attenuated for larger amounts of acid. Small amounts of chloride, of the order of 10-30 mol% with respect to palladium, improve both rate and selectivity, but only inhibiting effects are detected when chloride is added to the reaction mixture for the carbonylation of 2,4-dinitrotoluene to dimethyl 2,4-toluenedicarbamate. The data obtained and that previously reported in the literature has been analyzed in the context of a unifying mechanism and an explanation for some apparent contradictions has been given. 相似文献
132.
133.
Erika Ferrari Romano Grandi Sandra Lazzari Gaetano Marverti Maria Cecilia Rossi Monica Saladini 《Polyhedron》2007
The NMR study on the interaction of Pt(II) with Amadori compounds is performed. The Amadori compounds are derived from the reaction of β-d-glucose with l-cystine leading to N,N′-di-(1-deoxy-β-fructos-1-yl)-l-cystine [FruCyscys], and with l-methionine leading to N-(1-deoxy-β-fructos-1-yl)-l-methionine [FruMet]. 相似文献
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136.
Hiroshi Kageyama Takashi Watanabe Yoshihiro Tsujimoto Atsushi Kitada Yuji Sumida Kazuyoshi Kanamori Kazuyoshi Yoshimura Naoaki Hayashi Shigetoshi Muranaka Mikio Takano Monica Ceretti Werner Paulus Clemens Ritter Gilles Andr 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2008,120(31):5824-5829
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138.
A new approach to the determination of afiatoxins B1, B2, G1 and G2 is given; the method involves high-performance liquid chromatography with amperometric detection in the differential-pulse mode at the dropping mercury electrode with 1-s drop time. These aflatoxins can be determined simultaneously with good resolution but with some compromise in sensitivity. The detection limit of underivatized aflatoxin standards is around 5 ng. Average recoveries of aflatoxins from peanut butter by the Beebe method were G2 81%, G1 87%, B2 77% and B1 76%. 相似文献
139.
Irache JM Huici M Konecny M Espuelas S Campanero MA Arbos P 《Molecules (Basel, Switzerland)》2005,10(1):126-145
Bioadhesive nanoparticles have been proposed as carriers for the oral delivery of poorly available drugs and facilitate the use of this route. This work summarises some experiments describing the bioadhesive potential of Gantrez nanoparticles fluorescently labeled with rhodamine B isothiocyanate. The adhesive potential of Gantrez was found to be stronger when folded as nanoparticles than in the solubilised form. Conventional nanoparticles displayed a tropism for the upper areas of the gastrointestinal tract, with a maximum of adhesion 30 min post-administration and a decrease in the adhered fraction along the time depending on the given dose. The cross-linkage of nanoparticles with increasing amounts of 1,3-diaminopropane stabilised the resulting carriers and prolonged their half-life in an aqueous environment; although, the adhesive capacity of nanoparticles, the intensity and the relative duration of the adhesive interactions within the gut as a function of the cross-linking degree. Finally, nanoparticles were coated with either gelatin or albumin. In the first case, the presence of gelatin dramatically decreased the initial capacity of these carriers to interact with the gut mucosa and the intensity of these phenomenons. In the latter, bovine serum albumin coated nanoparticles (BSA-NP) showed an important tropism for the stomach mucosa without further significant distribution to other parts of the gut mucosa. 相似文献
140.
Monica?HanslienEmail author Kenneth H.?Karlsen Aslak?Tveito 《BIT Numerical Mathematics》2005,45(4):725-741
We analyze an explicit finite difference scheme for the general form of the Hodgkin-Huxley model, which is a nonlinear partial
differential equation coupled to a set of ODEs. The system of equations describes propagation of an electrical signal in excitable
cells. We prove that the numerical solution is bounded in the L∞-norm and L2 converges to a unique solution. The L∞-bound, which is the key point of our analysis, is proved by showing that the discrete solutions are invariant in a physically
relevant bounded region. For the convergence proof we use the compactness method.
AMS subject classification (2000) 65F20 相似文献