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排序方式: 共有172条查询结果,搜索用时 31 毫秒
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Fabrizio Colombo Alberto Damiano Irene Sabadini Daniele C. Struppa 《Journal of Geometric Analysis》2007,17(3):435-454
In this article we introduce a new notion of differential forms to describe the cohomology associated to the sheaf of regular
functions in several quaternionic variables. We then use these differential forms to introduce and describe concretely a sheaf
of quaternionic hyperfunctions as boundary values of regular functions in two quaternionic variables. We show how these ideas
can be generalized to the case of monogenic functions in two vector variables with values in a Clifford algebra. 相似文献
64.
Laura Ielo Laura Castoldi Saad Touqeer Jessica Lombino Alexander Roller Cristina Prandi Wolfgang Holzer Vittorio Pace 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(47):21038-21043
The selective formal insertion (homologation) of a carbon unit bridging the two trifluoroacetamidoyl chlorides (TFAICs) units is reported. The tactic is levered on a highly chemoselective homologation–metalation–acyl nucleophilic substitution sequence which precisely enables to assemble novel trifluoromethylated β-diketiminates within a single synthetic operation. Unlike previous homologations conducted with LiCH2Cl furnishing aziridines, herein we exploit the unique capability of iodomethyllithium to act contemporaneously as a C1 source (homologating effect) and metalating agent. The mechanistic rationale grounded on experimental evidences supports the hypothesized proposal and, the structural analysis gathers key aspects of this class of valuable ligands in catalysis. 相似文献
65.
Vittorio Pace Laura Castoldi Pilar HoyosJosé Vicente Sinisterra Massimo PregnolatoJosé Ma Sánchez-Montero 《Tetrahedron》2011,67(14):2670-2675
Very high regioselective 1,2-addition of organolithiums to α,β-unsaturated carbonyl-like compounds (ketones, aldehydes, and imines) in the presence of LiBr was achieved by carrying out reactions in the sustainable solvent 2-methyltetrahydrofuran. Excellent yields (in isolated product) of allylic alcohols and allylic amines were recovered under a simple experimental procedure at 0 °C. 相似文献
66.
Damiano Foschi 《偏微分方程通讯》2013,38(7-8):1537-1547
67.
Damiano Monticelli Antonino Di Iorio Elena Ciceri Alessio Castelletti Carlo Dossi 《Mikrochimica acta》2009,164(1-2):139-148
An empirical approach is presented for validating trace metal profiles in tree rings for use as environmental archives. Concentration profiles of Zn, Cd, Cu, Pb and U in tree rings and lake sediments are compared for assessing the reliability of the former as an environmental proxy. Laser ablation sampling in conjunction with inductively coupled plasma mass spectrometry (LA–ICP–MS) is used for the direct analysis of tree rings. An optimised analytical protocol is devised with particular emphasis on sample preparation and quantification strategy. Significant correlations in the two environmental archives were found for zinc, copper and uranium, while cadmium and lead temporal trends, although showing enrichment in recent years, do not agree with the concentration profiles in lacustrine sediment cores. A chemical model based on metal affinity for hard type ligands present in wood is proposed to explain these results. Moreover, spring and winter wood are analysed separately thanks to the high spatial resolution of laser ablation sampling. As a result, enhanced metal loadings are shown to lead to intraring differences in trace metal concentrations. 相似文献
68.
Alex M. Szpilman Dr. Damiano M. Cereghetti Dr. Jeffrey M. Manthorpe Dr. Nicholas R. Wurtz Dr. Erick M. Carreira Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(29):7117-7128
The use of molecular editing in the elucidation of the mechanism of action of amphotericin B is presented. A modular strategy for the synthesis of amphotericin B and its designed analogues is developed, which relies on an efficient gram‐scale synthesis of various subunits of amphotericin B. A novel method for the coupling of the mycosamine to the aglycone was identified. The implementation of the approach has enabled the preparation of 35‐deoxy amphotericin B methyl ester. Investigation of the antifungal activity and efflux‐inducing ability of this amphotericin B congener provided new clues to the role of the 35‐hydroxy group and is consistent with the involvement of double barrel ion channels in causing electrolyte efflux. 相似文献
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70.
Damiano Anselmi 《The European Physical Journal C - Particles and Fields》2010,65(3-4):523-536
If Lorentz symmetry is violated at high energies, interactions that are usually non-renormalizable can become renormalizable by weighted power counting. Recently, a CPT invariant, Lorentz violating extension of the Standard Model containing two scalar-two fermion interactions (which can explain neutrino masses) and four fermion interactions (which can explain proton decay) was proposed. In this paper we consider a variant of this model, obtained suppressing the elementary scalar fields, and argue that it can reproduce the known low-energy physics. In the Nambu–Jona-Lasinio spirit, we show, using a large N c expansion, that a dynamical symmetry breaking takes place. The effective potential has a Lorentz invariant minimum and the Lorentz violation does not reverberate down to low energies. The mechanism generates fermion masses, gauge-boson masses and scalar bound states, to be identified with composite Higgs bosons. Our approach is not plagued by the ambiguities of approaches based on non-renormalizable vertices. The low-energy effective action is uniquely determined and predicts relations among parameters of the Standard Model. 相似文献