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Gui Qiao XU Yong Sheng SUN Yong Ping LIU 《数学学报(英文版)》2006,22(6):1667-1678
In this paper, we consider the n-widths and average widths of Besov classes in the usual Sobolev spaces. The weak asymptotic results concerning the Kolmogorov n-widths, the linear n-widths, the Gel'fand n-widths, in the Sobolev spaces on T^d, and the infinite-dimensional widths and the average widths in the Sobolev spaces on Ra are obtained, respectively. 相似文献
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More periodic wave solutions expressed by Jacobi elliptic functions for the (2 + 1)-dimensional Konopelchenko–Dubrovsky equations are obtained by using the extended F-expansion method. In the limit cases, the solitary wave solutions and trigonometric function solutions for the equations are also obtained. 相似文献
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The He1 photoelectron (PE) spectra of both 2(5H) furanone and itstrans-chair-dimeric-compound (t-c-DFN) are reported. The assignment of the PES bands is made on the basis of band shapes, the PES results of the molecules
which have the similar atomic groups, and the restricted Hartree-Fock (RHF) calculations for the molecules studied. From the
results of both PES experimental and theoretical calculations, it is proved that the ionization potential (IPS) of the HOMO
for the dimeric-compound is lower than that of the HOMO for the monomer. And the total energy computed for thet-c-DFN is the lowest in the four possible configurations of dimeric-compounds of 2(5H) furanone. Therefore the synthesis oft-c-DFN is also the easiest.
Project supported by the National Natural Science Foundation of China. 相似文献
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The laser cladding of Fe-based alloys on a medium carbon steel substrate was performed using a CO2 laser and Ar shielding gas that was blown into a molten pool. The microstructure and cracking susceptibility of the laser-clad layers were studied in terms of carbon additions. Results show that the small change of the carbon content in the alloy powders can obviously change the microstructure and properties of the layers. When the carbon content is in the range of 0.3–0.4 wt.%, the decrease of the carbon content in alloy powders will increase the hardness and toughness of the layers simultaneously under the same process parameters. As a result, crack-free coatings with high hardness can be obtained. As the carbon content increases from 0.2 wt.% to 0.4 wt.%, the segregation ratio of chromium increases, while the segregation ratios of nickel, manganese, and silicon first decrease and then increase. At the same time, a new designing principle concerning the composition and microstructure has been put forward, and the principal mechanisms of strengthening and toughening of the layers are fine-grain strengthening and low carbon martensitic phase transformation strengthening. 相似文献
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Qi Sheng Liu Lian Dong Liu Jing Min Shi 《Acta Crystallographica. Section C, Structural Chemistry》2008,64(1):m58-m60
In the title centrosymmetric binuclear complex, [Cd2(C17H11N3O)4(H2O)2](ClO4)4, the CdII ion assumes a distorted octahedral geometry. There are π–π stacking interactions between the pyridine and 1,10‐phenanthroline ring systems of adjacent ligands at the same CdII centre. Intermolecular hydrogen bonds between the coordinated aqua ligand and the O atom of a keto group connect adjacent complex cations into extended chains. Hydrogen bonds also exist between the complex cations and the perchlorate anions. Compared with the fluorescence spectrum of the organic ligand, the complex displays strong fluorescent emission and an ipsochromic shift of the emission peaks, which may be attributed to the structural character. 相似文献