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71.
Paun Mihai 《Mathematische Annalen》1998,310(3):411-421
Sans résumé
Re?u le 7 Octobre 1996 相似文献
72.
Viorel P. Paun 《Central European Journal of Physics》2009,7(2):264-269
The SEM microfractographies of Zircaloy-4 are studied by the time-series method. We first develop a computer application which
associates a time series to each SEM micrograph. Furthermore, we will apply the phase space embedding technique to reconstruct
the attractor and to compute the autocorrelation dimension. Using the fractal analysis technique, the SEM microfractographies
of the fracture surface of the Zircaloy-4 samples have been analyzed.
相似文献
73.
High-resolution X-ray photoelectron spectroscopy was used to demonstrate that reduction of aqueous U6+ at ferrous mica surfaces at 25 degrees C preserves U5+ as the dominant sorbed species over a broad range of solution compositions. Polymerization of sorbed U5+ with sorbed U6+ and U4+ is identified as a possible mechanism for how mineral surfaces circumvent the rapid disproportionation of aqueous U5+. The general nature of this mechanism suggests that U5+ could play an important, but previously unidentified, role in the low-temperature chemistry of uranium in reducing, heterogeneous aqueous systems. 相似文献
74.
Bassil BS Kortz U Tigan AS Clemente-Juan JM Keita B de Oliveira P Nadjo L 《Inorganic chemistry》2005,44(25):9360-9368
The 6-cobalt-substituted [{Co3(B-beta-SiW9O33(OH))(B-beta-SiW8O29(OH)2)}2]22- has been characterized by IR and UV-vis spectroscopy, elemental analysis, magnetic studies, electrochemistry, and gel filtration chromatography. A single-crystal X-ray analysis was carried out on K10Na12[{Co3(B-beta-SiW9O33(OH))(B-beta-SiW8O29(OH)2)}2].49H2O (KNa-1), which crystallizes in the monoclinic system, space group P2(1)/n, with a=19.9466(8) A, b=24.6607(10) A, c=34.0978(13) A, beta=102.175(1) degrees, and Z=2. Polyanion 1 represents a novel class of asymmetric sandwich-type polyanions. It contains three cobalt ions, which are encapsulated between an unprecedented (B-beta-SiW9O34) fragment and a (B-beta-SiW8O31) unit. Polyanion 1 is composed of two sandwich species via two Co-O-W bridges in the solid state and almost certainly in solution as well based on gel filtration chromatography. UV-visible spectroscopy and cyclic voltammetry also confirmed its stability. Two well-separated groups of waves appeared in the voltammetric pattern: the wave observed in the negative potential range versus a saturated calomel electrode features the redox processes of WVI centers; the two reversible redox couples observed in the positive potential domain are attributed to the redox processes of Co2+ centers and indicated that the two types of Co2+ centers in the structure are oxidized in separate waves. Such reversibility of Co2+ centers within multi-Co-substituted polyoxometalates is uncommon. The magnetic properties of KNa-1 are also discussed. The ferromagnetic ground state has been studied by magnetic susceptibility and magnetization measurements and fitted according to an anisotropic exchange model. 相似文献
75.
Nicolae Hurduc Cristina Damian Anca Tarus Violeta Toader Natalia Hurduc 《Central European Journal of Chemistry》2005,3(1):53-62
The main objective of this paper is to study the thermal stability of some aromatic copolyethers containing a propylenic spacer.
Some of the investigated copolyethers displayed a liquid crystalline (LC) behavior, with the presence of the mesogenic groups
in the main chain, inducing high values of the thermal transition temperatures. As a consequence, a thermal stability study
was necessary to establish the maximum temperature value for the LC behavior characterization. A thermal degradation mechanism
is proposed, taking into consideration the azobenzenic unit as the weakest link in the polymer chain and thus, the starting
point of the thermal degradation process. The degradation mechanisms were correlated with the chemical structure and the polarity
and conformation of the chains. Conformational analysis was performed using molecular simulations. Freeman-Caroll and Coats-Redfern
methods were used to calculate some kinetic characteristics. 相似文献
76.
Buica George-Octavian Soare Maria-Laura Inel Georgiana Anca Razus Alexandru C. Birzan Liviu Oprisanu Alexandra Ungureanu Eleonora-Mihaela 《Journal of Solid State Electrochemistry》2016,20(11):3151-3164
Journal of Solid State Electrochemistry - The electrochemical behavior of substituted 1-phenylselanyl azulenes has been established by cyclic, differential pulse, and rotating disk electrode... 相似文献
77.
The quasilinearity of certain composite functionals associated to Schwarz’s celebrated inequality for inner products is investigated.
Applications for operators in Hilbert spaces are given as well. 相似文献
78.
79.
From a logical viewpoint, object is never defined, even by a negative definition. This paper is a theoretical contribution about object using a new constructivist logical approach called Logic of Determination of Objects founded on a basic operation, called
determination. This new logic takes into account cognitive problems such as the inheritance of properties by non typical occurrences or
by indeterminate atypical objects in opposition to prototypes that are typical completely determinate objects. We show how
extensional classes, intensions, more and less determined objects, more or less typical representatives of a concept and prototypes
are defined and organized, using a determination operation that constructs a class of indeterminate objects from an object
representation of a concept called typical object. 相似文献
80.
Anca Dumbravă Rodica Olar Mihaela Badea Maria Nicoleta Grecu Florentina Pătrascu Luminita Măruţescu Nicolae Stănică 《Journal of Thermal Analysis and Calorimetry》2014,115(3):2447-2455
New complexes ML(CNS)·nH2O [M = Ni, n = 0.5; M = Cu, n = 4.5; M = Zn, n = 0.5, HL: 6-mercapto-(1,4,8,11-tetraazaundecanyl)-6-carboxylic acid)] have been synthesised, chemical analysed, and characterised by different spectroscopic techniques (IR, UV–Vis–NIR, 1H NMR, EPR, ESI–MS), and magnetic measurements. Based on the IR spectra a dinuclear structure with the 1,3-CSN coordination was proposed for Ni(II) and Cu(II) complexes. The dinuclear structure of Cu(II) complex is also consistent with both magnetic behaviour and EPR spectrum. According to TG, DTG and DTA curves the thermal transformations are complex processes, including dehydration, Mannich base oxidative degradation and thiocyanate decomposition. The final product of decomposition is the most stable metallic oxide, as XRD data indicates. The new complexes were also screened for their microbicidal and antibiofilm properties. 相似文献