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181.
182.
Javier Mazuela Oscar Pàmies Montserrat Diéguez Laetitia Palais Stephane Rosset Alexandre Alexakis 《Tetrahedron: Asymmetry》2010,21(17):2153-2157
A biaryl-based monophosphoroamidite L1–L4a–f and aminophosphine L5–L7a–f ligand library was screened in the Rh-catalyzed asymmetric hydroformylation of several vinylarenes and heterocyclic olefins. Our results indicate that the selectivity is strongly dependent on the ligand parameters and on the substrate type. Enantioselectivities (up to 46%) were moderate in the hydroformylation of several vinylarenes S1–S5 and promising (up to 58%) for the more challenging heterocyclic olefins S6–S9. 相似文献
183.
It is well known that, in the plane, the boundary of any quadrature domain (in the classical sense) coincides with the zero set of a polynomial. We show, by explicitly constructing some four-dimensional examples, that this is not always the case. This confirms, in dimension 4, a conjecture of the second author. Our method is based on the Schwarz potential and involves elliptic integrals of the third kind. 相似文献
184.
185.
186.
Hernane T. Barcelos Luclecia D. Nunes Guilherme W. Tavares Edesio F. C. Alcantara Alexandre G. S. Prado 《Journal of Thermal Analysis and Calorimetry》2011,106(2):421-425
Silica gel was modified by silanization reaction followed by functionalization of histamine in a heterogeneous route. These
materials were characterized by elementary nitrogen and chloride analyses, porosity, thermogravimetry, and infrared. The functionalized
surface adsorbed Cu(II), Co(II), Ni(II), and Zn(II) ions in an aqueous solution at 25 °C. The isotherms of adsorption are
in accordance with Langmuir model and the surface presented a great potential to form complexes metal-surface in the chemical
reason of 1:1. 相似文献
187.
188.
François-René Alexandre Amaya BerecibarRoger Wrigglesworth Thierry Besson 《Tetrahedron》2003,59(9):1413-1419
Efficient microwave-assisted multi-step synthesis of 8H-quinazolino[4,3-b]quinazolin-8-one was investigated. The synthesis involved two Niementowski condensations from anthranilic acids. Homogeneous or heterogeneous conditions were studied with the aim to develop convenient syntheses of the desired compounds. 相似文献
189.
Alexandre Freire Stefan Müller Michael Struwe 《Annales de l'Institut Henri Poincaré (C) Analyse Non Linéaire》1998,15(6):725
We show that a weak limit of a sequence of wave maps in (1 + 2) dimensions with uniformly bounded energy is again a wave map. Essential ingredients in the proof are Hodge structures related to harmonic maps,
1 estimates for Jacobians,
1-BMO duality, a “monotonicity” formula in the hyperbolic context and the concentration compactness method. Application of similar ideas in the elliptic context yields a drastically shortened proof of recent results by Bethuel on Palais-Smale sequences for the harmonic map functional on two dimensional domains and on limits of almost H-surfaces. 相似文献
190.
We study the zero distribution of meromorphic functions of the formf(z)=Σ
k=1
∞
a
k/z−z
k
wherea
k
>0. Noting thatf is the complex conjugate of the gradient of a logarithmic potential, our results have application in the study of the equilibrium
points of such a potential.
Furthermore, answering a question of Hayman, we also show that the derivative of a meromorphic function of order at most one,
minimal type has infinitely many zeros.
Supported by an NSF grant.
Research carried out during a visit to the University of Illinois, funded by an NSF grant.
Research carried out at the University of York while serving as a British Science and Engineering Research Council (SERC)
fellow. The author gratefully acknowledges the hospitality and support extended to him by the Department of Mathematics. 相似文献