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排序方式: 共有226条查询结果,搜索用时 93 毫秒
1.
Alvisi D Blart E Bonini BF Mazzanti G Ricci A Zani P 《The Journal of organic chemistry》1996,61(20):7139-7146
The palladium-catalyzed desilylation-arylation of substituted vinylsilanes by p-iodoanisole in the presence of bidentate phosphine ligands is described. Apart from enhancing the rate of the reaction considerably, heteroatom-based functional groups in the vinylsilane moiety have a profound influence on the regiochemistry. A catalytic cycle for the chelation-controlled desilylation-arylation reaction involving five- and six-membered chelate rings is proposed. 相似文献
2.
Summary A rapid and simple method for the determination of both lysinoalanine (LAL) and protein hydrolysate amino acids after derivatization
with dansyl chloride (5-dimethylaminoaphtalene-1sulfonyl chloride) and separation with RP-HPLC (UV detection) is presented.
LAL is analysed in less than 15 minutes and complete separation of 22 amino acids is achieved in less than 30 minutes using
single linear gradients of solvents (phosphate buffer and acetonitrile). Quantitative results obtained by HPLC compare well
with results of the ion-exchange chromatography (amino acid analyser). The importance of the duration of the derivatization
reaction and of the excess of reagent is discussed. As examples, the results of the determination of LAL in two samples of
base treated α-casein and 22 samples of soy protein and the results of the analysis of amino acids in two balanced diet mixtures
are presented.
Presented at the 15th International Symposium on Chromatography, Nürnberg, October 1984 相似文献
3.
Maria Michaela Porzio Flavia Smarrazzo Alberto Tesei 《Archive for Rational Mechanics and Analysis》2013,210(3):713-772
Initial value problems for quasilinear parabolic equations having Radon measures as initial data have been widely investigated, looking for solutions which for positive times take values in some function space. In contrast, it is the purpose of this paper to define and investigate solutions that for positive times take values in the space of the Radon measures of the initial data. We call such solutions measure-valued, in contrast to function-valued solutionspreviously considered in the literature. We first show that there is a natural notion of measure-valued solution of problem (P) below, in spite of its nonlinear character. A major consequence of our definition is that, if the space dimension is greater than one, the concentrated part of the solution with respect to the Newtonian capacity is constant in time. Subsequently, we prove that there exists exactly one solution of the problem, such that the diffuse part with respect to the Newtonian capacity of the singular part of the solution (with respect to the Lebesgue measure) is concentrated for almost every positive time on the set where “the regular part (with respect to the Lebesgue measure) is large”. Moreover, using a family of entropy inequalities we demonstrate that the singular part of the solution is nonincreasing in time. Finally, the regularity problem is addressed, as we give conditions (depending on the space dimension, the initial data and the rate of convergence at infinity of the nonlinearity ψ) to ensure that the measure-valued solution of problem (P) is, in fact, function-valued. 相似文献
4.
Angela Somavilla Higioka Renata Cristina Messores Rudolf-Oliveira Flavia Martinello Maria Luiza Bazzo 《Accreditation and quality assurance》2016,21(2):143-149
Point-of-care (POC) testing of glucose (glucometers) represents a convenient alternative to monitor glycemia since the measurement procedure is performed without delay after sampling of the capillary blood, thereby avoiding the metabolism by the blood cells of glucose present in plasma. Likely because of sample instability, there is no proficiency test provider in Brazil for this type of POC sample. In this context, this study aimed to evaluate the analytical performance of glucometers used in a tertiary care hospital. The glucometers used were the Accu-Chek Performa® model from Roche Diagnostics, which use the principle of amperometry. The reference method was the reaction with modified hexokinase/glucose-6-phosphate in a Dimension® device. The stability evaluation of the control samples showed that it can be performed up to 90 min after the collection of whole blood samples. In the two rounds performed, only one result of the 17 glucometers evaluated was out of the threshold of two standard deviation. Thus, this method for control of glucometers met the expectations and enabled comparing the glucometers in a hospital. Given the current quality guidelines, daily internal quality control of glucometers is recommended, besides at least two annual comparisons between the results of the glucometers and the reference method and one EQA every 3 months. 相似文献
5.
Bianca Flavia Bonini Luca Bernardi Mauro Comes-Franchini Gabriella Dessole Mariafrancesca Fochi Alfredo Ricci 《Phosphorus, sulfur, and silicon and the related elements》2013,188(5-6):1273-1277
Abstract Enantiomerically pure 2-hydroxyalkyl, 2-aminoalkyl and 2-iminoalkyl ferrocenyl p-tolylsulfides are easily prepared in good yields and with complete diastereocontrol from (S)-(2-p-tolylthio)ferrocencarboxyaldehyde. 2-Iminoalkyl ferrocenyl derivatives can be used as ligands in asymmetric catalysis and as starting materials for asymmetric Staudinger reaction. 相似文献
6.
The unconventional methodology for the non-epimerizable cycloacetalization of optically active (1S,2S)-2-amino-1-(4-nitrophenyl)propane-1,3-diol (p-nitrophenylserinol) (condensed H2SO4 96% as solvent and catalyst, i.e., sulfuric transacetalization) producing (2R,4S,5S) diamino-1,3-dioxanes was enlarged by the use of N-protected forms of 2,2-dimethoxyethylamine (DMEA, aminoacetaldehyde dimethylacetal). Conversely, N-protected derivatives of p-nitrophenylserinol were successfully cyclocondensed with DMEA in the same sulfuric conditions. N-Functionalization of DMEA upon treatment with trimesic acid trichloride and cyanuric chloride yielded the corresponding triple amide and melamine, respectively. Their adapted sulfuric transacetalization in triplicate in reaction with arylserinols (aryl: phenyl, p-nitrophenyl) afforded a new series of optically active tripodands. 相似文献
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