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81.
In this text, we introduce and study involutive class groups and Brauer groups of a Krull domain R. We derive some exact sequences, connecting these groups and linking them to classical invariants, thus allowing to calculate them in concrete situations. We provide a geometric interpretation in terms of etale cohomology with respect to the sheaf of square roots of unity on Spec(R), as another useful tool to calculate these invariants. 相似文献
82.
83.
Juan Bory Reyes Richard Delanghe 《Mathematical Methods in the Applied Sciences》2008,31(12):1427-1439
A structure theorem is proved for the solutions to the Moisil–Théodoresco system in open subsets of ?3. Furthermore, it is shown that the Cauchy transform maps L2(?2, ?0, 2+) isomorphically onto H2(?+3, ?0, 3+), thus proving an elegant generalization to ?2 of the classical notion of an analytic signal on the real line. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
84.
Stephan Matos Camacho 《Discrete Mathematics》2009,309(15):4916-4919
In 1992 Gyárfás showed that a graph G having only k odd cycle lengths is (2k+1)-colourable, if it does not contain a K2k+2. In this paper, we will present the results for graphs containing only odd cycles of length 2m−1 and 2m+1 as done in [S. Matos Camacho, Colourings of graph with prescribed cycle lengths, diploma thesis, TU Bergakademie Freiberg, 2006. [3]]. We will show that these graphs are 4-colourable. 相似文献
85.
Reyes Malavé Osuna Rocio Ponce Ortiz Mari Carmen Ruiz Delgado Valentin G Nenajdenko Viktor V Sumerin Elizabeth S Balenkova Víctor Hernández Juan Teodomiro López Navarrete 《Chemphyschem》2007,8(5):745-750
Herein, we study the conjugation properties of three different thienoacenes, each of which has three or four fused thiophene rings, by means of Fourier transform Raman spectroscopy. The B3LYP/6-31G** vibrational analysis of all of the collected spectroscopic data evidences that the selective enhancement of a limited number of Raman scatterings is related to the occurrence in the three thienoacenes of a vibronic coupling between the lowest unoccupied frontier molecular orbital (LUMO) and some Raman-active skeletal nu(C==C) stretching modes of 1600-1300 cm(-1). 相似文献
86.
J. C. P. Pina A. M. Dias P. F. P. de Matos P. M. G. P. Moreira P. M. S. T. de Castro 《Experimental Mechanics》2005,45(1):83-88
In this paper we present the methods of determination and the stress obtained at the periphery of a cold expanded hole in
a 2024-T3 Alclad aluminum alloy sheet. The measurements in the aluminum clad were performed by the sin2Ψ method, taking experimental precautions to deal with the texture effects. In the core aluminum a special method had to be
implemented to determine the stress values in a direction not accessible to the X-ray diffraction. The strains were measured
in sample orientations selected according to the texture characteristics and stress factorsF
ij
were used to calculate the stress tensor. TheF
ij
values were determined assuming a quasi-isotropic material behavior, after concluding that the stress results were not significantly
affected by factors calculated for textured material. The residual stress profile, both in the clad and in the sheet, shows
a nearly axisymmetric stress state. Compressive stresses were observed near the periphery of the hole, with values that are
higher on the exit than on the entrance face. Residual stresses were also higher in the hoop direction than in the radial
direction. They decreased with the radial distance to the hole and affected the previous stress state over a distance of 6
mm. The plastic deformation induced by the cold expansion is well evidenced by the FWHM values, which in the affected zone
decrease with increasing distance from the hole edge. 相似文献
87.
Francisco Núñez‐Zarur Eduardo Arguello Ricardo Vivas‐Reyes 《International journal of quantum chemistry》2010,110(9):1622-1636
The electronic structure and reactivity trends of a set of tris‐(n‐methyl‐8‐quinolinolato) metal (III) (n = 0, 3, 4, 5; metal = Al+3, Ga+3) used as electron‐transport layer in organic light‐emitting diodes were studied and compared. All geometries were optimized at B3LYP/6‐31G(d,p) level of theory. The geometries of the ground state (S0) of unsubstituted molecules AlQ3 and GaQ3 were found to be slightly affected by the methyl group, which is in agreement with previous works. Methyl‐derivatives conserve largely the electronic structures of AlQ3 and GaQ3. The energies of the frontier orbitals highest occupied and lowest unoccupied molecular orbital are raised by the electron‐releasing effect of methyl group. Molecular orbital contribution analysis reveals that the orbital population is essentially the same for both MQ3 and their derivatives. Analyses of the ionization potential and electron affinity showed that MQ3 tend to be better hole‐blockers than methylated analogues and 5Me‐MQ3 have higher hole‐injection capability than the other methyl‐substituted derivatives. The global reactivity analysis showed that the electrophilicity index can be an indicator of electron‐injection capability in these complexes. Local reactivity analysis showed that atomic sites that are prone to nucleophilic/electrophilic attack are atoms C‐4 in L3/C‐5 in L1. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2010 相似文献
88.
Fluorescence microscopy offers an important tool for the study of complex biological phenomena such as symbiosis. Here we identify a strategy that adapts the unique differences between the secondary metabolism in host and guest symbiotic species to selectively image endosymbiotic organisms. The method is demonstrated by application to the complex symbiotic relationships in toxic marine dinoflagellates. 相似文献
89.
Mounce AM Oh S Mukhopadhyay S Halperin WP Reyes AP Kuhns PL Fujita K Ishikado M Uchida S 《Physical review letters》2011,106(5):057003
Competition with magnetism is at the heart of high-temperature superconductivity, most intensely felt near a vortex core. To investigate vortex magnetism we have developed a spatially resolved probe based upon NMR spin-lattice-relaxation spectroscopy. With this approach we have found a spin-density wave associated with the vortex core in Bi(2)Sr(2)CaCu(2)O(8+y), similar to checkerboard patterns in the local density of electronic states reported from scanning tunneling microscope experiments. We have determined both the spin-modulation amplitude and decay length from the vortex core in fields up to H=30 T. 相似文献
90.
The synthesis of a new azacyclophane formed by two l-tyrosine units joined by two methylene bridges is presented. The structural and conformational characteristics are briefly discussed. Spectroscopic and theoretical data reveal a syn structure with two intramolecular hydrogen bonds. 相似文献