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91.
Patrícia Homobono Brito de Moura Wolfgang Brandt Andrea Porzel Roberto Carlos Campos Martins Ivana Correa Ramos Leal Ludger A. Wessjohann 《Molecules (Basel, Switzerland)》2022,27(8)
A rare dihydoxyflavan-epicatechin proanthocyanidin, entcassiflavan-(4β→8)-epicatechin, was isolated from Dalbergia monetaria, a plant widely used by traditional people from the Amazon to treat urinary tract infections. The constitution and relative configuration of the compound were elucidated by HR-MS and detailed 1D- and 2D-NMR measurements. By comparing the experimental electronic circular dichroism (ECD) spectrum with the calculated ECD spectra of all 16 possible isomers, the absolute configuration, the interflavan linkage, and the atropisomers could be determined. 相似文献
92.
93.
da Silva Jussara Vieira Madurro Ana Graci Brito Madurro João Marcos 《Journal of Solid State Electrochemistry》2017,21(7):2129-2139
Journal of Solid State Electrochemistry - This paper reports a new platform for oligonucleotide hybridization, prepared by electropolymerization of 3-hydroxyphenylacetic acid onto gold electrode... 相似文献
94.
95.
E. Lazzaro R. Coelho 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,19(1):97-101
A major limit to steady state and advanced high operation of tokamaks of reactor class is due to the onset of tearing modes that develop magnetic and may cause loss of energy confinement or a major disruption. Here the structure of a classical problem
about the effects of external control helical fields is analysed and it is shown to offer a general paradigm of response of
low order classical and neoclassical tearing modes to a wide class of external perturbations. New results of principle on
the structural stability of the response model are obtained, leading to a clear interpretation of the role of “seed islands"
in the onset of neo-classical tearing modes and the role of finite ion larmor radius corrections to Ohm's law.
Received 12 November 2001 and Received in final form 4 January 2002 相似文献
96.
Mariana Köber Enrique Sahagún Martina Fuss Fernando Briones Mónica Luna Juan José Sáenz 《固体物理学:研究快报》2008,2(3):138-140
The effects of adhesion hysteresis in the dynamic‐dissipation curves measured in amplitude‐modulation atomic force microscopy are discussed. Hysteresis in the interaction forces is shown to modify the dynamics of the cantilever leading to different power dissipation curves in the repulsive and attractive regimes. Experimental results together with numerical simulations show that power dissipation, as measured in force microscopy, is not always proportional to the energy dissipated in the tip–sample interaction process. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
97.
Mariana Ciureanu Victor E. Sahini Felicia Cornea Cornelia Cercasov Mihai Contineanu 《Magnetic resonance in chemistry : MRC》1981,15(2):148-151
The barriers to internal rotation about the C? N bond in several thiopiperidides have been determined by the NMR technique. It was found that the barrier height (ΔG?) increases in the series cinnamoylthiopiperidide<thiobenzoylpiperidide<phenylthioacetylpiperidide. This trend was discussed in terms of the electronic structure, using HMO calculations. For m-and p-substituted cinnamoylthiopiperidides the barriers were shown to increase with the electron withdrawing character of the substituent in the aromatic ring. 相似文献
98.
Lejeune C Coelho C Bonhomme-Coury L Azaïs T Maquet J Bonhomme C 《Solid state nuclear magnetic resonance》2005,27(4):242-246
We show that it is possible to efficiently transfer magnetization from 31P to 29Si, using variable amplitude CP MAS experiment. This experiment is demonstrated by using Si5O(PO4)6, the synthesis protocol of which is described. From the obtained results, we show that the experiment allows the spectral edition of 29Si spectra from 31P→29Si CP, enabling the studies of derivatives involving Si–O–P linkages, such as phosphosilicate glasses, microporous silicoaluminophosphates (SAPO) and bioactive phosphosilicates. 相似文献
99.
100.
Zaqueu Coelho 《Transactions of the American Mathematical Society》2004,356(11):4427-4445
For a minimal circle homeomorphism we study convergence in law of rescaled hitting time point process of an interval of length 0$">. Although the point process in the natural time scale never converges in law, we study all possible limits under a subsequence. The new feature is the fact that, for rotation numbers of unbounded type, there is a sequence going to zero exhibiting coexistence of two non-trivial asymptotic limit point processes depending on the choice of time scales used when rescaling the point process. The phenomenon of loss of tightness of the first hitting time distribution is an indication of this coexistence behaviour. Moreover, tightness occurs if and only if the rotation number is of bounded type. Therefore tightness of time distributions is an intrinsic property of badly approximable irrational rotation numbers.