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981.
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
982.
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
983.
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
984.
985.
986.
Pico-second photoelectric characteristic in manganite oxide La0.67Ca0.33MnO3 films 总被引:1,自引:0,他引:1 下载免费PDF全文
Ultrafast photoelectric characteristic has been observed in La0.67Ca0.33MnO3 films on tilted SrTiO3 substrates. A pico-second (ps) open-circuit photovoltage of the perovskite manganese oxide films has been obtained when the films were irradiated by a 1.064μm laser pulse of 25 ps duration. The rise time and full width at half-maximum of the photovoltage pulse are ~300 ps and ~700 ps, respectively. The photovoltaic sensitivity was as large as ~500 mV/mJ. 相似文献
987.
The AME 2020 atomic mass evaluation (I). Evaluation of input data,and adjustment procedures 下载免费PDF全文
This is the first of two articles(Part I and Part II)that presents the results of the new atomic mass evaluation,Ame2020.It includes complete information on the experimental input data that were used to derive the tables of recommended values which are given in Part II.This article describes the evaluation philosophy and procedures that were implemented in the selection of specific nuclear reaction,decay and mass-spectrometric data which were used in a least-squares fit adjustment in order to determine the recommended mass values and their uncertainties.All input data,including both the accepted and rejected ones,are tabulated and compared with the adjusted values obtained from the least-squares fit analysis.Differences with the previous Ame2016 evaluation are discussed and specific examples are presented for several nuclides that may be of interest to Ame users. 相似文献
988.
为判断泉州湾海岸线变迁所处的状态,引入分形分析法,对泉州湾海岸线的分维值进行计算.采用时间序列上的泉州湾海岸线数据,运用海岸线分形网格计算方法,计算了泉州湾总体海岸线及各分岸段海岸线分维数,分析了总体海岸和各分岸段分维数变化过程,并试探地将分维变化值的大小作为判断海岸线冲淤严重程度的依据.结果表明:泉州湾海岸线可用分维作其良好的表征参数;从海岸线分维值的变化趋势可判断出海岸线变迁是否处于动态平衡中的稳定状态,泉州湾分维变化幅值大于0.035,表示海岸线冲淤程度严重. 相似文献
989.
利用形态特征与RAPD分析技术,分析了国内不同地区的24份普通白菜(Brassica campestris L.ssp.chinensis(L.)Makino var.communis Tsee et Lee.)种质的遗传多样性.结果表明,13个形态学性状的变异系数为12.4%~69.9%,其中叶柄变异最大,子叶变异最小.24份普通白菜材料在形态学聚类的距离5处聚为4类.利用筛选出的15条RAPD引物从24份普通白菜材料中共扩增出113条带,其中多态性条带83条,多态率73.4%,平均每条引物条带7.53条、多态性条带5.53条.RAPD数据聚类在相似系数0.77处,分为8类,与形态聚类间有重叠和细分.以形态聚类4个类别计算的Nei's基因多样性指标H和Shannon信息指数I,均为第Ⅳ大类第Ⅰ大类第Ⅲ大类第Ⅱ大类,第Ⅳ类的H和I分别为0.2395和0.3523.而不同地区则以江淮地区的Nei's基因多样性H和Shannon信息指数I最高,分别为0.2076和0.3098.这些结果与普通白菜种质资源多样性特征以及地区分布相吻合. 相似文献
990.
根据大型脉冲功率装置中的绝缘堆的结构特点,设计了一个新的四层轴向小型绝缘堆.它由四层绝缘环构成,分隔水界面与真空界面.在该绝缘结构开展静电场计算和电路仿真计算后,进行了有机玻璃小型绝缘堆的真空沿面闪络实验,实验结果反映了有机玻璃圆环结构的耐压特性.根据实验结果推算圆环结构下有机玻璃的材料常数,并计算了绝缘堆的闪络概率.圆环绝缘结构的尺寸大于一般真空沿面闪络实验中常用的圆柱与圆台结构绝缘子,结构和尺寸更接近于实际工程应用的绝缘堆结构,从实验结果中得到的关键材料常数将更适用于评估大型绝缘堆结构的闪络概率. 相似文献