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861.
Mössbauer spectra of KSnBr3·2H2O were very broad and could not fit Lorentz equation, suggesting unresolvable quadrupole doublets. Its quadrupole splitting was estimated to be about 0.25 mm/s from the separate experiments on frozen aqueous solutions of Sn(II)-Br? systems. Stability constants of bromostannate(II) complexes were determined at μ = 3.5 from the Δ-cL curve by the approximation method, which were in agreement with the literature values. 相似文献
862.
W. -L. Hsu 《Combinatorica》1986,6(4):381-385
This paper describes a decomposition scheme for coloring perfect graphs. Based on this scheme, one need only concentrate on
coloring highly connected (at least 3-connected) perfect graphs. This idea is illustrated on planar perfect graphs, which
yields a straightforward coloring algorithm. We suspect that, under appropriate definition, highly connected perfect graphs
might possess certain regular properties that are amenable to coloring algorithms.
This research has been supported in part by National Science Foundation under grant ECS—8105989 to Northwestern University. 相似文献
863.
Hui-Kai Zeng Anting Hsiao Wei-Hsiu Hsu Shao-Wei Wu Jiunn-Yuan Lin Kaung-Hsiung Wu Jenh-Yih Juang Tseng-Ming Uen Yi-Shun Gou Jen-Tsai Kuo 《Applied Superconductivity, IEEE Transactions on》2004,14(1):107-111
Cross-coupled planar microwave filters were fabricated using YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// superconducting thin films deposited on both sides of a LaAlO/sub 3/ single crystal substrate by pulsed laser deposition. The hairpin resonator geometry allows one to miniaturize the 3-GHz filters by compacting the entire filter onto a substrate with dimensions 0.5 cm /spl times/ 1 cm. By adjusting the relative spacing among the resonators to establish adequate couplings, filters with very sharp rejection skirt and extremely small insertion loss in passband were obtained. 相似文献
864.
865.
This article presents a new technique of optical heterodyne interferometry to measure the refractive index of some unknown liquid. It's based on total-internal-reflection heterodyne interferometry and the uses of fiber sensor technology. 相似文献
866.
R. S. Chen Z. B. Ye Edward K. N. Yung K. F. Tsang 《International Journal of Infrared and Millimeter Waves》2003,24(8):1325-1339
A gradient optimization technique along with a definition of cost function is applied to the CAD of the circulator with a magnetized ferrite sphere for millimeter wave communications. A three-dimensional Finite-Difference Time-Domain (FDTD) approach for the analysis of this ferrite sphere based microstrip circulator is presented. The topology of the structure is enforced at each step of optimization and its physical dimensions are used as optimization variables. The cost function is defined using location of zeros and poles of the circulator's transmission, isolation, and reflection functions. Numerical tests show that the optimization process converges from an arbitrarily selected starting point with the new definition of the cost function. 相似文献
867.
868.
A Raman-mechanical technique was used to study the relationship between stress distribution and fiber orientation in model composites. Our experimental data generally were consistent with most simplistic mechanical models. A more complete analysis, using the Eshelby equivalent inclusion method, fitted our experimental data exceptionally well. For large applied strains, compressive failure occurred for fibers which were oriented at high angles relative to the draw direction. This occurred because of the lateral shrinkage associated with the matrix when the sample was stretched. The effect of fiber end geometry on the stress distribution for these misaligned fibers was the same as observed earlier. Tapered-end fibers generally carried loads more efficiently in composites than blunt-end fibers. 相似文献
869.
Recently, we have developed several synthetic routes to the new classes of chalcogen-containing manganese carbonyl clusters, and the interesting structural transformations and reactivity of the resultant clusters have been investigated as well. In this short review, the syntheses and bonding modes of the sulfur, selenium, and tellurium-containing manganese carbonyl complexes reported by our laboratory will be presented, and the cluster growth and transformation will be systematically compared and discussed. 相似文献
870.
Chun‐Guey Wu Hung‐Chieh Lu Liang‐Nien Chen Yung‐Chou Lin 《Journal of polymer science. Part A, Polymer chemistry》2008,46(5):1586-1597
Two new 1,10‐phenanthroline (Phen) containing conjugated oligomers, oligo‐3,8‐bis(4‐octylthiophene‐2‐yl)‐1,10‐phenanthroline) (PDTPh) and oligo‐3,8‐bis‐(4‐octyl‐5‐(4‐ctylthiophene‐2‐yl)thiophene‐2‐yl)‐1,10‐phenanthroline) (PTTPh), as well as their corresponding monomers (OTPhOT and OTOTPhOTOT) were prepared and their metal ion‐sensing properties were investigated. The oligomers showed high thermal stability, good proccessibility, and gave varied color when reacted with different metal ions. Oligomers also showed distinct responses toward metal ions when compared with their corresponding monomers, suggesting that the ionochromic responses were determined by not only the coordinating ability of Phen unit but also the conformation of oligomer chains. Moreover, the differences in the ion‐sensing behaviors between OTPhOT and OTOTPhOTOT also suggested that the coordination ability of Phen depends on its substituents. The oligo‐alkylthiophene moieties in PDTPh and PTTPh acted as spacers to reorganize the conformation of the oligomer chains, as well as the electron donating groups to adjust the coordination ability of the Phen. These findings provide a clue for designing Phen‐containing ion‐sensors for specified ion‐sensing applications. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1586–1597, 2008 相似文献