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排序方式: 共有311条查询结果,搜索用时 15 毫秒
71.
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73.
Sang-Hyun Eom Ying Zheng Edward Wrzesniewski Jaewon Lee Neetu Chopra Franky So Jiangeng Xue 《Organic Electronics》2009,10(4):686-691
We investigate the performance of FIr6-based deep-blue phosphorescent organic light-emitting devices (PHOLEDs) with three different electron transport materials, bathocuproine (BCP), 4,7-diphenyl-1,10-phenanthroline (BPhen), and tris[3-(3-pyridyl)mesityl]borane (3TPYMB), and study the effect of doping alkaline metals (Li and Cs) into these charge transport materials. External quantum efficiency (ηEQE) of (20 ± 1)% and peak power efficiency (ηP) of (36 ± 2) lm/W were achieved maintaining Commission Internationale de L’Eclairage (CIE) coordinates of (x = 0.16, y = 0.28) in p-i-n dual-emissive-layer (D-EML) deep-blue PHOLEDs with 3TPYMB as the electron transport material and 3TPYMB:Cs as the electron injection layer. The high efficiencies are attributed to the high triplet energy of 3TPYMB as well as the increased conductivity of 3TPYMB:Cs. 相似文献
74.
Treatment of a wide range of functionalized hydroxyallenic esters with 5 mol % Ph(3)PAuCl and 5 mol % AgOTf in CH(2)Cl(2) at 25 °C for 1 h produced selectively 2-alkyl- and aryl-3-ethoxycarbonyl-2,5-dihydrofurans in good to excellent yield through intramolecular hydroalkoxylation by a 5-endo mode. 相似文献
75.
H. Kwak G. H. Eom S. H. Lee H. G. Koo S. P. Jang J. Lee W. Shin M. S. Lah C. Kim S.-J. Kim Y. Kim 《Journal of Structural Chemistry》2010,51(5):923-930
Five new Ni(II) complexes with pyridine carboxamide ligands have been synthesized and the crystal structures of three of the complexes were determined. Strong distortion effects of 6-methyl substitution were observed in the complexes with 6-methyl-substituted pyridyl bpb ligands. The C-H...F and C-H...O hydrogen bond interactions build extended architectures in the crystals studied. This result suggests that the steric effect of 6-methyl substitution plays an important role in the distortion of the structure, and the 6-methyl substitution can facilitate hydrogen bond interactions between methyl hydrogen atoms and O(carbonyl) or F atoms. Twelve Ni(II) complexes, including seven complexes reported previously, show reversible redox behavior, implying that the reduced Ni(I) state of each complex is stable in the time scale of CV measurement. The steric effect of R1 substituent and the electronic effects of X1 and X2 groups were found to be the main factors contributing to the shift of the redox potential of the Ni(II) complexes 相似文献
76.
Radiation from a ferrite-filled slot array antenna with a superstrate is investigated. The Fourier transform and mode matching are utilised to obtain a rigorous solution. The radiation patterns of a ferrite-filled slot array antenna with a superstrate are measured at 10.05 GHz to confirm good agreement with computational results. 相似文献
77.
Jun-Bong Eom Tae-Jin Lee 《Communications Letters, IEEE》2010,14(1):60-62
Dynamic Framed-Slotted ALOHA (DFSA) is one of the most popular algorithms to resolve tag collision in RFID systems. In DFSA, it is widely known that the optimal performance is achieved when the frame size is equal to the number of tags. So, a reader dynamically adjusts the next frame size according to the current number of tags. Thus it is important to estimate the number of tags accurately. In this paper, we propose a novel tag estimation method for DFSA. We compare the performance of the proposed method with those of other existing methods. And, simulation results show that our scheme improves the accuracy of tag estimation and the speed of tag identification. 相似文献
78.
H. J. Park D. H. Lee M. Kim D. S. Eom Y-K. Chang 《Journal of Infrared, Millimeter and Terahertz Waves》2005,26(1):117-124
A compact beam-steering lens design appropriate for millimeter-wave and submillimeter-wave applications is experimentally verified with an X-band test model. The lens achieves coupling to plane-wave beams through arrays of patch antennas placed on its two outer surfaces. The isolation between input and output antennas is accomplished by inserting a metal ground plane in the middle of the lens. The two closest patch antennas on the front and the backside are connected together with microstrip circuits that include switched-line phased shifters and interconnecting vias through the lens substrate. Three different X-band 100-element plane-wave microstrip lenses that use passive delay lines instead of actual phase-shifters were fabricated to successfully demonstrate the beam-steering angles of 20 and 40 degrees. From a separate waveguide measurement on the unit-cell element only, the insertion loss of the lens was estimated to be approximately 3.5 dB with bandwidth of 2% at 10 GHz. 相似文献
79.
[reaction: see text]. We herein report the development of one-pot procedures for the conversion of allyl aryl ethers to 2-methylbenzofurans (via sequential Claisen rearrangement and oxidative cyclization) and for the conversion of aryl homoallyl ethers to chromenes (via direct oxidative cyclization). It is likely that both reactions proceed via a common Pd-catalyzed pathway involving olefin activation, nucleophilic attack, and beta-hydride elimination. 相似文献
80.
D. W. Kim Y. S. Jeon T. Y. Eom M. Y. Suh C. H. Lee 《Journal of Radioanalytical and Nuclear Chemistry》1991,150(2):417-426
A study on the separation of Li isotopes was carried out with a resin having monobenzo-15-crown-5 as a functional group, synthesized by substitution reaction of chloromethylated styrene-DVB copolymer with 4-aminobenzo-15-crown-5. Adsorption properties of the resin for Li+ were invesgated with batch method in various solvents and counter anions. Upon column chromatography [0.9 cm (I. D.)×25 cm (height)] using 5% (v/v) H2O in acetonitrile as an eluent, single separation factor, , 1.053 (±0.005), (6Li/7Li)resin/ (6Li/7Li) solution was obtained by the GLUECKAUF method from the elution curve and isotope ratios. 相似文献