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991.
X.Q. Meng D.Z. Shen J.Y. Zhang Y.M. Lu Z.Z. Zhang X.W. Fan 《Solid State Communications》2005,135(3):179-182
High quality vertical-aligned ZnO nanorod arrays were synthesized by a simple vapor transport process on Si (111) substrate at a low temperature of 520 °C. Field-emission scanning electron microscopy (FESEM) showed the nanorods have a uniform length of about 1 μm with diameters of 40-120 nm. X-ray diffraction (XRD) analysis confirmed that the nanorods are c-axis orientated. Selected area electron diffraction (SAED) analysis demonstrated the individual nanorod is single crystal. Photoluminescence (PL) measurements were adopted to analyze the optical properties of the nanorods both a strong UV emission and a weak deep-level emission were observed. The optical properties of the samples were also tested after annealing in oxygen atmosphere under different temperatures, deep-level related emission was found disappeared at 600 °C. The dependence of the optical properties on the annealing temperatures was also discussed. 相似文献
992.
讨论了容斥原理及其推广,在此基础上研究了在限制条件下对称群Sn中累计计数问题及其推广。 相似文献
993.
Kexin Li Yanhong Luo Zhexun Yu Minghui Deng Dongmei Li Qingbo Meng 《Electrochemistry communications》2009,11(7):1346-1349
Porous carbon counter electrodes have been fabricated at low temperature by coating an organic binder free carbon slurry onto F-doped tin oxide conducting glass. The carbon slurry is prepared by ball-milling a dispersion of activated carbon in aqueous SnCl4 solution. During ball-milling, SnCl4 hydrolyzes and transforms into stannic acid gel, which acts as an inorganic “glue” to connect the carbon particles during film preparation. Dye-sensitized solar cells employing this carbon electrode achieve efficiency as high as 6.1% which is comparable to that of the cells using sputtering Pt as counter electrode. 相似文献
994.
995.
本文导出了一个简化的流量率公式,并利用这个公式分析了流量率与齿形及齿廓参数的关系。并提出了一些提高流量率的方法。 相似文献
996.
Navigation and surveillance applications require tracking constant input/bias targets. When the target's trajectory follows a constant input/bias constraint, model mismatching caused by conventional tracking algorithms can be handled by a delayed update filter (DUF). The statistical convergence and stability properties of the delayed update filter were studied to insure the rationality of its steady-state analysis. A steady-state filter gain was then designed for a constant-gain DUF to reduce the computations without much performance loss. Simulations demonstrate the potential of the constant-gain DUF, and the CGDUF is nearly 60% faster than the DUF without much loss in steady-state tracking accuracy. 相似文献
997.
Venkat R. Donuru Giri K. Vegesna Singaravelu Velayudham Ge Meng Haiying Liu 《Journal of polymer science. Part A, Polymer chemistry》2009,47(20):5354-5366
Novel deep‐red emissive poly(2,6‐BODIPY‐ethynylene)s bearing dodecyl side chains (polymers A , B , and C ) have been prepared by palladium‐catalyzed Sonogashira polymerization of 2,6‐diiodo‐functionalized BODIPY monomers with 2,6‐diethynyl‐functionalized BODIPY monomers. These polymers emit in the deep‐red region with emission maxima at up to 690 nm, and exhibit significant red shifts (up to 166 and 179 nm) of both absorption and emission maxima compared with their parent BODIPY dyes due to significant extension of π‐conjugation. These polymers possess good thermal stability with decomposition temperature between 270 and 360 °C. The polymers exhibit a little larger Stokes shifts and shorter lifetime than their corresponding BODIPY dyes. The solid state thin films of polymers A , B , and C emit in near‐infrared region between 723 and 743 nm, and show significantly red shifts (up to 57 nm) in absorption and emission maxima relative to their polymer solution. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 5354–5366, 2009 相似文献
998.
Hong‐Cheu Lin Meng‐Dan Jiang Shen‐Chang Wu Leng‐Long Jou Kai‐Pin Chou Ching‐Mao Huang Kung‐Hwa Wei 《Journal of polymer science. Part A, Polymer chemistry》2009,47(18):4685-4702
A series of diblock‐copolymers were synthesized through anionic polymerization of styrene and tert‐butyl methacrylate (tBuA) with different monomer ratios, and analogous block‐copolymeric derivatives (PS‐b‐PAA)s with monofunctional carboxylic acid groups were obtained by further hydrolyzation as hydrogen‐bonded (H‐bonded) proton donors. Via H‐bonded interaction, these diblock‐coplymeric donors (PS‐b‐PAA)s were incorporated with luminescent mono‐pyridyl/bis‐pyridyl acceptors to form single/double H‐bonded supramolecules, that is, H‐bonded side‐chain/cross‐linking copolymers, respectively. The supramolecular architectures formed by donor polymers and light‐emitting acceptors were influenced by the ratio of acid blocks in the diblock copolymeric donors and the type of single/double H‐bonded light‐emitting acceptors. Their thermal and luminescent properties can be adjusted by H‐bonds, and more than 100 nm of red‐shifted photoluminescence (PL) emissions were observed, which depend on the degrees of the H‐bonding interactions. Self‐assembled phenomena of amphiphilic dibolck copolymers and their H‐bonded complexes were confirmed by TEM micrographs, and supramolecular microphase separation of spherical micelle‐like morphology was demonstrated to affect the photophysical properties. Polymer light‐emitting diode (PLED) devices containing H‐bonded complexes showed electroluminescence (EL) emissions of 503–560 nm under turn‐on voltages of 7.5–9.0 V, maximum power efficiencies of 0.23–0.37 cd/A (at 100 mA/cm2), and maximum luminances of 318–519 cd/m2 (around 25 V). © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 4685–4702, 2009 相似文献
999.
Fan Liu Qing Li Hong Yang Xiao‐Ling Cai Xue‐Kui Xia Sheng‐Ping Chen Meng‐Feng Li Zhi‐Gang She Yong‐Cheng Lin 《Magnetic resonance in chemistry : MRC》2009,47(5):453-455
Two new natural products, tenelate A ( 1 ) and B ( 2 ), together with the known compound, tenellic acid C ( 3 ), were isolated from the mangrove endophytic fungus Talaromyces sp. (SBE‐14), from the South China Sea. Their structures were elucidated by spectroscopic methods, mainly 1D and 2D NMR techniques. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
1000.
Dong Han Xiang-Bao Meng Lin-Na Wang Hong Liu Yun Yao Zhuo Wang Zhen-Jun Yang Zhen-Min Liu Zhong-Jun Li 《Tetrahedron: Asymmetry》2009,20(4):399-410
A series of novel alkyl substituted fructose-based oxadiazoles were synthesized and their cytotoxic activities toward tumor cells were investigated. We studied the reaction mechanism and the stereochemistry of the reaction. Tautomerization between isomers 2 and 3 was observed in solution. The tautomerization was accelerated by heating or in the presence of acetic acid. An intermediate 6 during the heterocyclization was isolated, and two different pathways for the heterocyclization were suggested. On the basis of these findings, an efficient method, with the assistance of microwave irradiation was developed for the synthesis of 4 and 5. The yields were satisfactory and no by-products were found. We also proposed that the (R/S)-configurations of oxadiazoles were determined by the E/Z configurations of hydrazones. 相似文献