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41.
Alessandro Casoni Giuseppe Celentano Francesca Clerici Alessandro Contini Maria Luisa Gelmi Giuseppe Mazzeo Sara Pellegrino Carlo Rosini 《Tetrahedron: Asymmetry》2009,20(19):2247-2256
Herein we report a mild and efficient method to synthesize chiral 3-aminosubstituted isothiazole sulfoxides taking advantage of (+)- and (?)-((8,8-dichlorocamphoryl)sulfonyl)oxaziridine under microwave irradiation. The determination of the absolute configuration of the chiral sulfoxide was achieved by theoretical calculation of the CD spectra. The reason for the observed stereoselectivity was enlightened by means of analysis of our data using DFT calculations. 相似文献
42.
Dorina Mitrea Irina Mitrea Marius Mitrea Elia Ziadé 《Journal of Functional Analysis》2012,262(11):4766-4830
We are concerned with establishing completeness and separability criteria for large classes of topological vector spaces which are typically non-locally convex, including Lebesgue-like spaces, Lorentz spaces, Orlicz spaces, mixed-normed spaces, tent spaces, and discrete Triebel–Lizorkin and Besov spaces. For vector spaces of measurable functions we also derive pointwise convergence results. Our approach relies on abstract capacitary estimates and works in certain cases of interest even in the absence of a background measure space and/or of a vector space structure. 相似文献
43.
This article presents a novel shock‐capturing technique for the discontinuous Galerkin (DG) method. The technique is designed for compressible flow problems, which are usually characterized by the presence of strong shocks and discontinuities. The inherent structure of standard DG methods seems to suggest that they are especially adapted to capture shocks because of the numerical fluxes based on suitable approximate Riemann solvers, which, in practice, introduces some stabilization. However, the usual numerical fluxes are not sufficient to stabilize the solution in the presence of shocks for large high‐order elements. Here, a new basis of shape functions is introduced. It has the ability to change locally between a continuous or discontinuous interpolation depending on the smoothness of the approximated function. In the presence of shocks, the new discontinuities inside an element introduce the required stabilization because of numerical fluxes. Large high‐order elements can therefore be used and shocks captured within a single element, avoiding adaptive mesh refinement and preserving the locality and compactness of the DG scheme. Several numerical examples for transonic and supersonic flows are studied to demonstrate the applicability of the proposed approach. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
44.
Ioana Dorina Vlaicu Madalina Constand Rodica Olar Dana Marinescu Maria Nicoleta Grecu Veronica Lazar Mariana Carmen Chifiriuc Mihaela Badea 《Journal of Thermal Analysis and Calorimetry》2013,113(3):1369-1377
Three new coordinative compounds that contain mixed ligands (5,6-dimethylbenzimidazole and acrylato anion) were synthesized and characterized. The features of complexes have been assigned from microanalytical, IR, UV–Vis and EPR spectra as well as thermal analysis. IR data are in accordance with unidentate nature of 5,6-dimethylbenzimidazole while the acrilato ion acts as uni- or bidentate ligand. The electronic spectra display the characteristic pattern of square pyramidal or octahedral stereochemistry, which were confirmed by the EPR spectra. Antibacterial and antifungal activities of the complexes have been determined in vitro, against various Gram-negative and Gram-positive bacteria and fungi. The tested complexes exhibited different spectra of antimicrobial activity and inhibited the microbial ability to colonize the inert surfaces, acting as potential anti-adherence and biofilm-controlling agents. Thermal decomposition evidenced several well-defined steps as dehydration (complex 2), 5,6-dimethylbenzimidazole molecule release (all complexes) and the acrylate decomposition in carbonate (complex 3). The final residue is in all cases copper (II) oxide. 相似文献
45.
Hodisan Teodor Casoni Dorina Beldean-Galea Mihail Simion Cimpoiu Claudia 《平面色谱法杂志一现代薄层色谱法》2008,21(3):213-215
JPC – Journal of Planar Chromatography – Modern TLC - 相似文献
46.
The problem of minimizing a polynomial function in several variables over R
n is considered and an algorithm is given. When the polynomial has a minimum the algorithm returns the global minimal value and finds at least one point in every connected component of the set of minimizers. A characterization of such points is given. When the polynomial does not have a minimum the algorithm computes its infimum. No assumption is made on the polynomial. 相似文献
47.
In the present study, dynamic differential scanning calorimetry has been used to investigate the effect of an alkali lignin in amounts up to 20% by weight, on the crosslinking kinetics of an epoxy prepolymer cured with an aliphatic polyamine. Lignin presence does not significantly affect the overall reaction order, but the activation energy increases and the slowing of the overall curing process with lignin content could be explained by the interaction between lignin and the polyamine hardener. The possibility of having a “false compensation” in the case of the use of single DSC scans is also discussed. 相似文献
48.
Alessandro D'Aprano Rosario De Lisi Dorina Ines Donato 《Journal of solution chemistry》1983,12(6):383-400
The densities, heat capacities, and dilution enthalpies ofn-pentanol+2-methyl-2-butanol mixtures have been measured, in many cases as a function of temperature, over the complete mole fraction range. Excesses thermodynamic properties, apparent and partial molar heat capacities, volumes and expansibilities were derived. The concentration and temperature dependences of these functions are discussed in terms of the variations of the structure of the system caused by the participation of the two alcohol molecules (with quite different steric hindrance of the alkyl chain around the-OH group) in the dynamic intermolecular association process through hydrogen bonding. 相似文献
49.
Sava DF Kravtsov VCh Nouar F Wojtas L Eubank JF Eddaoudi M 《Journal of the American Chemical Society》2008,130(12):3768-3770
Two novel porous zeolitelike metal-organic frameworks (ZMOFs) were constructed via the single metal ion-based molecular building block approach from rigid and directional tetrahedral building units and pyrimidinecarboxylate bridging ligands; their ion exchange and hydrogen sorption properties were evaluated. 相似文献
50.
The synthesis of a set of bipyridine-containing macrocycles by oxidative acetylene-acetylene dimerization is described. The cycles are separated by preparative GPC, and the smallest homologue is analyzed by single-crystal X-ray diffraction, which shows a layered structure with channels that are partially filled with parts of the flexible chains of adjacent macrocycles. The cyclic trimer has a D3h symmetry and is a possible candidate for the formation of metal organic supramolecular assemblies on surfaces. 相似文献