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31.
S.H Chen 《Journal of luminescence》2004,109(2):93-102
The ZnS:Cu,Al,Au (P22G) phosphor powder was bombarded by an electron beam in an O2 ambient, Ar ambient and other mixture of gases. These gases consisted of mixtures of O2 and COx, and O2, COx and Ar gas. Auger electron spectroscopy (AES) was used to monitor changes in the surface composition of the P22G phosphor during electron bombardment. When the P22G phosphor powder was exposed to the electron beam in a water-rich O2 ambient, a chemically limited ZnO layer was formed on the surface. The electron beam degradation of the P22G phosphor powder was also performed in a dry O2 ambient and a layer of ZnSO4 was formed on the surface. The ZnSO4 formation decayed exponentially with time and it is postulated that this was due to the diffusion of the charge reactants through the ZnSO4 film to the reaction interfaces. The P22G phosphor exposed to the electron beam in an Ar ambient and to the other gas mixtures degraded at a lower rate than in the case of the O2 ambient. This suggests that Ar and COx may suppress the degradation of the P22G phosphor powder. 相似文献
32.
5‐Methylene‐2‐oxazolidinone (1) and 5‐methylene‐1,3‐thiazolidine‐2‐thione (4) react with various isocyanates to give the corresponding urethanes 3 and 5 in high yields in the presence of palladium(0) or palladium(II) catalyst under mild reaction conditions. A mechanism is proposed. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
33.
34.
Zhen‐Feng Chen Hong‐Li Zhou Hong Liang Yan Li Ren‐Gen Xiong Xiao‐Zeng You 《应用有机金属化学》2003,17(11):883-884
The centrosymmetric binuclear structure of [Pb2(H‐Norf)2(ONO2)4]shows the geometry around each lead(II) atom to be distorted trigonal bipyramidal with Pb–O distances ranging from 2.357(3) to 2.769(4) Å. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
35.
Chongyu Mei Junqiao Ding Bing Yao Yanxiang Cheng Zhiyuan Xie Yanhou Geng Lixiang Wang 《Journal of polymer science. Part A, Polymer chemistry》2007,45(9):1746-1757
Two orange phosphorescent iridium complex monomers, 9‐hexyl‐9‐(iridium (III)bis(2‐(4′‐fluorophenyl)‐4‐phenylquinoline‐N,C2′)(tetradecanedionate‐11,13))‐2,7‐dibromofluorene (Br‐PIr) and 9‐hexyl‐9‐(iridium(III)bis(2‐(4′‐fluorophenyl)‐4‐methylquinoline‐N,C2′)(tetradecanedionate‐11,13))‐2,7‐dibromofluorene (Br‐MIr), were successfully synthesized. The Suzuki polycondensation of 2,7‐bis(trimethylene boronate)‐9,9‐dioctylfluorene with 2,7‐dibromo‐9,9‐dioctylfluorene and Br‐PIr or Br‐MIr afforded two series of copolymers, PIrPFs and MIrPFs, in good yields, in which the concentrations of the phosphorescent moieties were kept small (0.5–3 mol % feed ratio) to realize incomplete energy transfer. The photoluminescence (PL) of the copolymers showed blue‐ and orange‐emission peaks. A white‐light‐emitting diode with a configuration of indium tin oxide/poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate)/PIr05PF (0.5 mol % feed ratio of Br‐PIr)/Ca/Al exhibited a luminous efficiency of 4.49 cd/A and a power efficiency of 2.35 lm/W at 6.0 V with Commission Internationale de L'Eclairage (CIE) coordinates of (0.46, 0.33). The CIE coordinates were improved to (0.34, 0.33) when copolymer MIr10PF (1.0 mol % feed ratio of Br‐MIr) was employed as the white‐emissive layer. The strong orange emission in the electroluminescence spectra in comparison with PL for these kinds of polymers was attributed to the additional contribution of charge trapping in the phosphorescent dopants. © 2007 Wiley Periodicals, Inc. JPolym Sci Part A: Polym Chem 45: 1746–1757, 2007 相似文献
36.
For the linear deterministic system with unknown orders and coefficients adaptive controls are given so that the closed-loop system is stabilized and the unknown parameters are consistently estimated. Moreover, if the parameter estimation is ignored, then the system input and output can be reduced to zero with an exponential rate.This project is supported by the National Natural Science Foundation of China.In Commemoration of the 15th Anniversary of the Acta Mathematicae Applicatae Sinica. 相似文献
37.
38.
P. C. Chen 《中国化学会会志》1995,42(5):755-760
Three ab initio calculations (HF/6-3IG, HF/6-3IG*, and HF/6-3IG**) on 2,4,6-trinitrotoluene were made, The results compare well with xray data, except dihedral angles of NO2 relative to the plane of the benzene ring. The deviations are attributed to packing forces and steric effects in the crystal. The most stable structure was a torsional angle 10° of the methyl top with the benzene ring, unlike toluene. The rotational barriers of the methyl top and the 4-nitro group are small. Hydrogen bonding, dipole moments and total atomic charges arc calculated. 相似文献
39.
1989年发表的Bager第五图,包含关于三角形元素的35个二次规范画数之间的51个不等式通过细致的分析,本文给出了其中遗漏的12个基本不等式 相似文献
40.
Sheng‐Huei Hsiao Chien‐Wei Chen Guey‐Sheng Liou 《Journal of polymer science. Part A, Polymer chemistry》2004,42(13):3302-3313
Two new diamines, 2,4‐diaminotriphenylamine ( 3 ) and N‐(2,4‐diaminophenyl)carbazole ( 4 ), were synthesized via the cesium fluoride‐mediated aromatic substitution reactions of 1‐fluoro‐2,4‐dinitrobenzene with diphenylamine and carbazole, followed by palladium‐catalyzed hydrazine reduction. Amorphous and soluble aramids having pendent diphenylamino and carbazolyl groups were prepared by the phosphorylation polycondensation of aromatic dicarboxylic acids with diamines 3 and 4 , respectively. The aramids derived from diamine 3 had sufficiently high molecular weights to permit the casting of flexible and tough films. They exhibited excellent mechanical properties and moderately high softening temperatures in the 221–298 °C range. However, the reactions of diamine 4 with aromatic diacids gave relatively lower molecular weights products that could not afford flexible films. For a comparative purpose, the parent aramids derived from m‐phenylenediamine and aromatic diacids were also prepared and characterized. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 3302–3313, 2004 相似文献