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Two ternary solid complexes, Tb3+ (Eu3+)-ciprofloxacina-acetylacetone, have been synthesied and chara-cterized by elemental analysis, IR. Ciprofloxacina is one kind of bacteriophage containing α-carbonyl carboxylic acid configurayion and acetylacetone contains β-diketonate configurayion. They are the ideal ligands for Tb3+ and Eu3+. The fluorescence spectra of Tb3+ and Eu3+ complexes showed that the ligands were suitable for efficient energy transfer from ligands to the Tb3+ or Eu3+ ion with a high fluorescence quantum yield, large stoke shift, narrow emission bonds and large fluorescence lifetime. So the complexes were the new kind of solid fluorescence materials. Moreover, the mechanisms of the fluorescence of Tb3+ (Eu3+)-ciprofloxacina-acetylacetone ternary solid complex were investigated. 相似文献
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针对使用可压缩流动数值方法求解不可压缩流动存在的刚性问题,基于虚拟压缩法思想,构造了一种以Mach数、速度、密度、温度等变量为元素的预处理矩阵,改变了控制方程组的特征根并使其量级更接近.通过理论推导与分析,证明新方法相比Weiss, Pletcher, Dailey和Choi的方法而言,不仅能降低方程组的刚性,提高了数值求解效率,而且拥有更好的稳定性,此外还能实现低速流动和高速流动之间的光滑过渡.采用有限差分格式进行离散,对流项的Roe格式作为基本加权无振荡(WENO)格式的求解器,黏性项则使用中心型紧致差分格式来计算,与预处理矩阵相结合展开数值实验,结果表明新预处理方法可以实现对无黏和有黏不可压缩流动问题的高精度模拟,且拥有比Weiss和Pletcher等提出的方法更好的收敛性和稳定性. 相似文献
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斐波那契(Fibonacci,1170—1245),又称比萨的莱昂那多,意大利数学家.为了向欧洲人介绍印度和阿拉伯的数字系统及其计算方法,他于1202年出版了《计算之书》(Liber Abaci).这是一部百科全书式的数学著作,涉及算术、代数和问题解决等在13世纪广为人知的数学知识.该书问世后的 相似文献
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The third-order optical nonlinearities of [(CH3)4N]Au(dmit)2 (dmit = 4,5-dithiolate-1,3-dithiole-2-thione) at 532 nm and 1064 nm are investigated using the Z-scan technique with pulses of picoseconds duration. The Z-scan spectra reveal a strong nonlinear absorption (reverse saturable absorption) and a negative nonlinear refraction at 532 nm. No nonlinear absorption is observed at 1064 nm. The molecular second-order hyperpolarizability γ for the [(CH3)4N]Au(dmit)2 molecule at 532nm is estimated to be as high as (2.1 ±0.1) × 10^-31 esu, which is nearly three times larger than that at 1064 nm. The mechanism responsible for the difference between the results is analysed. Nonlinear transmission measurements suggest that this material has potential applications in optical limiting. 相似文献
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Photoluminescence spectroscopy is used to study defects found in single ZnO nano/microwires at 90 K. The defect, acting as binding site for bound exciton (BX) transition, is represented by BF, the fractional intensity of the BX peak in the whole near-band edge ultraviolet (UV) luminescence. The concentration of defects as origins of the visible emissions is proportional to the intensity fraction DF, i.e., the intensity fraction of visible emissions in the sum total of all UV and visible luminescences. By comparing BF and DF, it is concluded that the two defects are not correlated to each other. The former kind of defect is considered to be related to the blueshift of the near-band edge peak as the radius of the nano/microwires decreases at room temperature. 相似文献
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