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111.
NianYuanTAN XiaoMingXIAO ZeLinLI TakekoMATSUMURA-INOUE 《中国化学快报》2004,15(6):687-690
A new cobalt(Ⅱ) complex with tridentate ligand 2, 6-bis (benzimidazol-2-yl)pyridine has been synthesized by microwave irradiation method and characterized by elemental analysis,electrochemical and spectral methods. The binding of the complex with calf thymus DNA has also been investigated by absorption and fluorescence spectra. 相似文献
112.
Baker‘s yeast mediated reduction of optically active diketone is described. The two keto groups are efficiently differentiated and the ee value of the recovered material is considerably raised. It affords highly optically active key intermediates efficiently for the synthesis of natural polyhydroxylated agarofuran products. 相似文献
113.
114.
Thermal oxidation of polyethylene filled with dispersed copper and containing an amine antioxidant was studied. The concentration ranges in which the catalytic effect of the metal on the polymer oxidation or the stabilizing effect of the antioxidant prevails were determined. Under certain conditions, dispersed copper enhances the stabilizing effect of the antioxidant. 相似文献
115.
Ding-Bing Lin Ping-Hung Chiang Hsueh-Jyh Li 《Vehicular Technology, IEEE Transactions on》2005,54(1):136-148
Based on Alamouti code, Lee and Williams proposed two-branch transmit diversity block-coded orthogonal frequency-division multiplexing (TDBC-OFDM) systems, namely, space-time block-coded OFDM (STBC-OFDM) and space-frequency block-coded OFDM (SFBC-OFDM). However, they employed the simple maximum-likelihood (SML) detector, which was designed under the assumption that the channel is static over the duration of a space-time/frequency codeword. Therefore, STBC-OFDM/SFBC-OFDM suffers from the high time/frequency selectivity of the wireless mobile fading channel. In this paper, besides the original SML detector, three detectors proposed by Vielmon et al. are applied to improve the two-branch TDBC-OFDM systems. Additionally, assuming sufficient cyclic prefix, the performances of all systems in spatially uncorrelated time-varying multipath Rayleigh-fading channels are evaluated by theoretical derivation and computer simulation, as well. According to the derived bit-error rate (BER), we further derive the bit-error outage (BEO) to provide a more object judgment on the transmission quality within a fading environment. Numerical results have revealed that significant performance improvement can be achieved even when the systems are operated in highly selective channels. 相似文献
116.
Silver and copper nanowires have been synthesized using a scalable method of AC electrodeposition into porous aluminum oxide templates, which produces gram quantities of metal nanowires ca. 25 nm in diameter and up to 5 and 10 μm in length for Ag and Cu, respectively. The nanowires have been used to prepare polystyrene nanocomposites by solution processing. Electrical resistivity measurements performed on polymer nanocomposites containing different volume fractions of metal indicate that low percolation thresholds of nanowires are attained between compositions of 0.25 and 0.75 vol %. 相似文献
117.
Shih-Kai Lee Mao-Chao Lin 《Communications, IEEE Transactions on》1995,43(5):1917-1925
We propose a hybrid ARQ scheme which uses QPSK modulation for the first transmission and BPSK modulation for retransmissions. The throughput performance of the proposed ARQ scheme is better that those of ARQ schemes purely using QPSK modulation or purely using BPSK modulation for transmissions. Furthermore, the proposed scheme does not require any operation of error correction as usually required in hybrid ARQ schemes. Therefore, the ARQ scheme proposed in this paper can be easily implemented 相似文献
118.
Han-Bin Lin Jung-Young Su Yu-Pin Liao Way-Seen Wang 《Quantum Electronics, IEEE Journal of》1995,31(6):1131-1139
By using micro-prisms, improved three-dimensional (3-D) bends of the embedded and buried waveguides of step-index profile are proposed. A simple phase compensation rule for the optimal design of the micro-prism is also presented. Through the simulation of 3-D semivectorial finite-difference beam propagation method, the transmission characteristics of the improved bends are shown to have been enhanced dramatically as compared with those of the conventional ones. Even for a bend angle of as large as 10°, the normalized transmitted power can still be greater than 95%. These results of 3-D bends are then compared with those of the two-dimensional (2-D) ones which are simplified from 3-D structures by the effective index method, and physical explanation of the discrepancy between the 3-D and 2-D results is introduced. The influences of waveguide structures and prism parameters on the transmission characteristics are discussed in detail. Some criteria for the design of large-angle low-loss 3-D improved bends are also accessed 相似文献
119.
Lin Huaxin 《数学年刊B辑(英文版)》1993,14(3):387-396
The author studies the problem whether a multiplier of a hereditary C^*-subalgebra B of a C^*-algebra A can be extended to a multiplier of A. One related problem is the Hahn-Banach extension theorem for Hilbert modules over C^*-algebras. It is shown that every self-dual Hilbert module over W^*-algebra or an injective C^*-algebra is injective. 相似文献
120.
Three hen egg-white lysozyme inhibitor producing strains, Enterobacter cloacae M-1002, E. sakazakii M-1204, and Erwinia rhapontici H-55, were isolated from the soils of Taiwan. E. cloacae M-1002 appeared to be a promising inhibitor producing strain. One inhibitor was isolated from the culture broth of this strain. Maximum lysozyme inhibitory activity was obtained when the bacterium was grown aerobically in a medium consisting of 0.75% glucose, 0.25% beef extract, 1.0% polypeptone, and 0.25% sodium L-glutamate (pH 70) at 37 °C after 36–48 hrs. A hen egg-white lysozyme inhibitor was isolated from the culture broth of this strain. The inhibitor was purified from the culture supernatant of E. cloacae M-1002 by ammonium sulfate fractionation, DEAE-Sepharose CL-6B column chromatography and Fractogel TSK HW-55 (S) gel chromatography. Molecular weight of the purified lysozyme inhibitor was estimated to be 18, 000–20, 000 by SDS-PAGE and HPLC, and was composed of 71% amino acid and 23% total sugar. Serine, glycine, and alanine in a 3:2:1 molar ratio were the major amino acids, calculated to be 32.8, 20.3, and 11.4% (mol%), respectively. Glucose and mannose were the major sugar components of the inhibitor. The inhibitor was stable at pH 5 to 8 and was stable under 50 °C. Only hen egg-white lysozyme was inhibited by the purified inhibitor but not the other tested enzymes such as lysozyme of celery, turnip; lytic enzyme of Pseudomonas aeruginosa M-1001; chitinase/lysozyme of P. aeruginosa K-187; or cellulase and xylanase of Streptomyces actuosus A-151 and Aspergillus sp. G-393. The inhibition of lysozyme to the bacterial cell lytic activity by the purified inhibitor was 100%. 相似文献