排序方式: 共有158条查询结果,搜索用时 15 毫秒
21.
Tommaso Flaminio Lluís Godo Enrico Marchioni 《International Journal of Approximate Reasoning》2013,54(4):491-512
In this paper we present a generalization of belief functions over fuzzy events. In particular we focus on belief functions defined in the algebraic framework of finite MV-algebras of fuzzy sets. We introduce a fuzzy modal logic to formalize reasoning with belief functions on many-valued events. We prove, among other results, that several different notions of belief functions can be characterized in a quite uniform way, just by slightly modifying the complete axiomatization of one of the modal logics involved in the definition of our formalism. 相似文献
22.
Clayden J Vallverdú L Clayton J Helliwell M 《Chemical communications (Cambridge, England)》2008,(5):561-563
Tertiary diamides of xanthene-1,8-dicarboxylic acid and biphenyl-2,2'-dicarboxylic acid exhibit a thermodynamic preference for anti stereochemistry which is inverted in the presence of Ti- or Sn-based Lewis acids, allowing interconversion between kinetically stable syn and anti diastereoisomeric atropisomers. 相似文献
23.
Farrera JA Canal I Hidalgo-Fernández P Pérez-García ML Huertas O Luque FJ 《Chemistry (Weinheim an der Bergstrasse, Germany)》2008,14(7):2277-2285
The tautomeric equilibria of 2-(4'-hydroxyphenylazo)benzoic acid (HABA) and 2-(3',5'-dimethyl-4'-hydroxyphenylazo)benzoic acid (3',5'-dimethyl-HABA) have been studied by a combination of spectroscopic and computational methods. For neutral HABA in solvents of different polarity (toluene, chloroform, DMSO, DMF, butanol, and ethanol) the azo tautomer (AT) is largely predominant. For monoanionic HABA, the hydrazone tautomer (HT) is the only detected species in apolar solvents such as toluene and chloroform, while the AT is the only detected species in water and a mixture of both tautomers is detected in ethanol. Comparison of the results obtained for HABA and its 3',5'-dimethylated derivative shows that dimethylation of the hydroxybenzene ring shifts the tautomeric preferences towards the hydrazone species. These findings have been used to examine the differences in binding affinity to streptavidin, as the lower affinity of HABA can be explained in terms of the larger energetic cost associated with the tautomeric shift to the bioactive hydrazone species. Overall, these results suggest that a balanced choice of chemical substituents, embedding environment, and pH can be valuable for exploitation of the azo-hydrazone tautomerism of HABA biomimetics in biotechnological applications. 相似文献
24.
Mesa JA Velázquez-Palenzuela A Brillas E Coll J Torres JL Juliá L 《The Journal of organic chemistry》2012,77(2):1081-1086
The condensation reaction of D-maltose to free radicals of the series of tris(2,4,6-trichlorophenyl)methyl (TTM) and tris(perchlorophenyl)methyl (PTM) has been described for the first time. The new persistent radicals 1 and 2 are very stable and have been characterized by EPR. Their cyclic voltammograms show a quasi-reversible process in the cathode, being reduced to the corresponding anions, with redox potentials a little lower than those of TTM and PTM, respectively. Their oxidant activity is in close relation with their reduction potentials. Therefore, while 2 is reduced by ascorbic acid, 1 remains unaltered. 相似文献
25.
Lluís Cabedo José Luis Feijoo María Pilar Villanueva José María Lagarón Enrique Giménez 《Macromolecular Symposia》2006,233(1):191-197
Biodegradable blends of amorphous poly(lactic acid) (aPLA) and polycaprolactone (PCL) and nanocomposites of these blends were developed by melt blending. A morphological study of the bioblends was carried out by means of WAXS and SEM showing immiscible behavior. The nanocomposites were also characterized morphologically by WAXS, TEM and SEM, revealing high degree of interaction of the nanoclays with the aPLA. Mechanical, thermal and gas barrier properties of the different blends and nanocomposites were studied and the effect of blending and clay addition on the above-mentioned properties was evaluated. 相似文献
26.
In this paper, we extend Walsh’s stochastic integral with respect to a Gaussian noise, white in time and with some homogeneous
spatial correlation, in order to be able to integrate some random measure-valued processes. This extension turns out to be
equivalent to Dalang’s one. Then we study existence and regularity of the density of the probability law for the real-valued
mild solution to a general second order stochastic partial differential equation driven by such a noise. For this, we apply
the techniques of the Malliavin calculus. Our results apply to the case of the stochastic heat equation in any space dimension
and the stochastic wave equation in space dimension d=1,2,3. Moreover, for these particular examples, known results in the literature have been improved.
相似文献
27.
Potential Analysis - We prove absolute continuity of the law of the solution, evaluated at fixed points in time and space, to a parabolic dissipative stochastic PDE on L2(G), where G is an open... 相似文献
28.
Popovici M Gich M Roig A Casas L Molins E Savii C Becherescu D Sort J Suriñach S Muñoz JS Baró MD Nogués J 《Langmuir : the ACS journal of surfaces and colloids》2004,20(4):1425-1429
Monoliths of iron oxide-silica aerogel nanocomposites have been synthesized using a novel synthesis route which consists of impregnating silica wet gels with anhydrous iron(II) precursors followed by ethanol supercritical drying of the gels. The process yields aerogels exhibiting high porosity, large surface areas (approximately 900 m2/g), rather low densities (approximately 0.6 g/cm3), and a homogeneous distribution of single-phase maghemite, gamma-Fe2O3, nanoparticles with average sizes in the 7-8 nm range. Remarkably, the gamma-Fe2O3 nanoparticles are obtained in the as-dried state without the need of postannealing. The nanoparticles are mostly superparamagnetic at room temperature but become blocked in a ferrimagnetic state at lower temperatures. 相似文献
29.
Multiple Decay Mechanisms and 2D‐UV Spectroscopic Fingerprints of Singlet Excited Solvated Adenine‐Uracil Monophosphate 下载免费PDF全文
Dr. Quansong Li Dr. Angelo Giussani Dr. Javier Segarra‐Martí Dr. Artur Nenov Dr. Ivan Rivalta Prof. Alexander A. Voityuk Prof. Shaul Mukamel Dr. Daniel Roca‐Sanjuán Prof. Marco Garavelli Prof. Lluís Blancafort 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(22):7497-7507
The decay channels of singlet excited adenine uracil monophosphate (ApU) in water are studied with CASPT2//CASSCF:MM potential energy calculations and simulation of the 2D‐UV spectroscopic fingerprints with the aim of elucidating the role of the different electronic states of the stacked conformer in the excited state dynamics. The adenine 1La state can decay without a barrier to a conical intersection with the ground state. In contrast, the adenine 1Lb and uracil S(U) states have minima that are separated from the intersections by sizeable barriers. Depending on the backbone conformation, the CT state can undergo inter‐base hydrogen transfer and decay to the ground state through a conical intersection, or it can yield a long‐lived minimum stabilized by a hydrogen bond between the two ribose rings. This suggests that the 1Lb, S(U) and CT states of the stacked conformer may all contribute to the experimental lifetimes of 18 and 240 ps. We have also simulated the time evolution of the 2D‐UV spectra and provide the specific fingerprint of each species in a recommended probe window between 25 000 and 38 000 cm?1 in which decongested, clearly distinguishable spectra can be obtained. This is expected to allow the mechanistic scenarios to be discerned in the near future with the help of the corresponding experiments. Our results reveal the complexity of the photophysics of the relatively small ApU system, and the potential of 2D‐UV spectroscopy to disentangle the photophysics of multichromophoric systems. 相似文献
30.
In order to account for the high stereoselectivity observed in the intramolecular cobalt-mediated bis-annulation of 2a,b a SN1 epimerization of the C(5) assymmetric center must be postulated. 相似文献