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151.
Juan M. Antelo Florencio Arce Juan Crugeiras Julia Franco Pilar Rodriguez Angel Varela 《国际化学动力学杂志》1990,22(12):1271-1282
This article reports the kinetics of the decomposition of N-bromoserine formed rapidly by bromation of serine by BrO?. The main decomposition products are glycolaldehyde, ammonia, carbon dioxide, and bromide ions at pH < 11.5, and β-hydroxypyruvic acid, ammonia, and bromide ions at pH > 11.5. The reaction is of order one with respect to N-bromoserine, and is independent of ionic strength and excess serine. The rate constant increases with increasing pH at pH > 11 and with decreasing pH at pH < 8, and over the range pH 8–11 has the constant value 1.67 × 10?3 s?1 at 298 K. 相似文献
152.
Fernandez de Bobadilla Javier; Gaffney Terence 《Journal London Mathematical Society》2008,77(3):545-557
Lê numbers were introduced by Massey with the purposeof numerically controlling the topological properties of familiesof non-isolated hypersurface singularities and describing thetopology associated with a function with non-isolated singularities.They are a generalization of the Milnor number for isolatedhypersurface singularities. In this note the authors investigatethe composite of an arbitrary square-free f and z2. They geta formula for the Lê numbers of the composite, and considertwo applications of these numbers. The first application isconcerned with the extent to which the Lê numbers areinvariant in a family of functions which satisfy some equisingularitycondition, the second is a quick proof of a new formula forthe Euler obstruction of a hypersurface singularity. Severalexamples are computed using this formula including any X definedby a function which only has transverse D(q, p) singularitiesoff the origin. 相似文献
153.
In this paper we extend and generalize several known estimates for homogeneous polynomials and multilinear mappings on Banach spaces. Applying the theory of absolutely summing nonlinear mappings, we prove that estimates which are known for mappings on ?p spaces in fact hold true for mappings on arbitrary Banach spaces. 相似文献
154.
Explicit lower bounds are given for the size of the imaginary parts of resonances for Schrödinger operators with non-trapping or trapping potentials, and for the Dirichlet Laplacian in the exterior of a star-shaped obstacle, both acting in three dimensions.Work partially supported by DiUC/FONDECYT (Chile)Work partially supported by U.S. National Science Foundation grant DMS 8705610 相似文献
155.
156.
Cláudia M. Morais Valérie Montouillout Michael Deschamps Dinu Iuga Franck Fayon Filipe A. A. Paz João Rocha Christian Fernandez Dominique Massiot 《Magnetic resonance in chemistry : MRC》2009,47(11):942-947
From one‐ to two‐ and three‐dimensional MAS NMR solid‐state experiments involving 31P and 27Al, we show that the structure of microporous alumino‐phosphate AlPO4‐40 contains at least four times more sites than expected, and we attribute two types of AlIV sites. The newly described 27Al‐31P MQ‐HMQC opens new possibilities of describing details of three‐dimensional bounded networks. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
157.
158.
Pérez CM Rodríguez-Delgado A Palma P Álvarez E Gutiérrez-Puebla E Cámpora J 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(46):13834-13842
Manganese alkyl complexes stabilised by 2,6-bis(N,N'-2,6-diisopropyl-phenyl)acetaldiminopyridine ((iPr)BIP) have been selectively prepared by reacting suitable alkylmanganese(II) precursors, such as homoleptic dialkyls [(MnR(2))(n)] or the corresponding THF adducts [{MnR(2)(thf)}(2)] with the mentioned ligand. For R=CH(2)CMe(2)Ph or CH(2)Ph, formally Mn(I) derivatives are produced, in which one of the two R groups migrates to the 4-position of the central pyridine ring in the (iPr)BIP ligand. In contrast, a true dialkyl complex [MnR(2)((iPr)BIP)] can be isolated for R=CH(2)SiMe(3). In solution, this compound slowly evolves to the corresponding Mn(I) monoalkyl derivative. A detailed study of this reaction provides insights on its mechanism, showing that it proceeds through successive alkyl migrations, followed by spontaneous dehydrogenation. Protonation of [Mn(CH(2)SiMe(3))(2)((iPr)BIP)] with the pyridinium salt [H(Py)(2)][BAr'(4)] (Ar'=3,5-C(6)H(3)(CF(3))(2)) leads to the cationic species [Mn(CH(2)SiMe(3))(Py)((iPr)BIP)](+). Alternatively, the same complex can be produced by reaction of the pyridine complex [{Mn(CH(2)SiMe(3))(2)(Py)}(2)] with the protonated ligand salt [H(iPr)BIP](+)[BAr'(4)](-). This last reaction allows the synthesis of analogous cationic alkylmanganese(II) derivatives, when precursors of type [MnR(2)((iPr)BIP)] are not available. Treatment of these neutral and cationic (iPr)BIP alkylmanganese derivatives with a range of typical co-catalysts (modified methylaluminoxane (MMAO), B(C(6)F(5))(3), trimethyl or triisobutylaluminum) does not lead to active ethylene polymerisation catalysts. 相似文献
159.
Joana Ferreira da Costa Franco Fernández Xerardo García-Mera Pilar Midón 《Tetrahedron》2010,66(34):6797-6805
Starting from readily available N-benzyl protected methyl 3,5-bis(hydroxymethyl)pirrolidinecarboxylate a number of racemic methyl t-3,t-5-disubstitutedprolinates have been synthesised, thus opening a practical way towards the preparation of a variety of putative proline-mimetics. In this context, N-Boc protected derivatives proved to be better intermediates than their N-benzyl counterparts in terms of cleanness and overall yield of the synthetic procedure. 相似文献
160.
Francisco J. Salgado Sara Vázquez Amparo Pérez-Díaz Pilar Arias 《Analytica chimica acta》2010,658(1):18-3648
Serum is a typical sample for non-invasive studies in clinical research. Its proteome characterization is challenging, since requires extensive protein depletion. Methods used nowadays for removal of high-abundance proteins are expensive or show quite often a low loading capacity, which has strong repercussions on the number of samples and replicates per analysis.In order to deplete immunoglobulins (Igs) and albumin (HSA) from 1 mL serum samples, we have developed a protocol based on a combination of thiophilic chromatography, not previously used in clinical proteomics, and a HSA-specific resin. Ig/HSA-depleted samples, immunoglobulinome and albuminone were analyzed by 2-DE. Thiophilic chromatography, coupled with HSA-depletion, allows a good 2-DE resolution as well as the visualization of new spots. Moreover, it yields enough protein to evaluate technical variability and facilitate subsequent protein identification. To validate the protocol, we carried out a preliminary comparative study between triplicate Igs/HSA-depleted serum samples from healthy control individuals and recently diagnosed/untreated rheumatoid arthritis (RA) patients. RA patients showed several acute phase proteins, as well as additional serum proteins, differentially and significantly regulated.Therefore, thiophilic chromatography can be used as an efficient and economical method in 2-DE to deplete immunoglobulins from large human serum samples before a more extensive fractioning. 相似文献