赵洁
,
姚秉华
,
冯逸晨
功能材料
采用共沉淀法制备BiNbO4纳米棒。利用X射线粉末衍射仪（XRD）、透射电镜（TEM）、紫外-可见漫反射光谱（UV-Vis DRS）和热重分析（TG/DTA）对其结构、形貌和性质进行表征,并通过紫外-可见分光光度计分析BiNbO4纳米棒光降解罗丹明B来研究其光催化活性。结果表明以五氧化二铌和五水硝酸铋为原料制备得到正交相结构的BiNbO4纳米棒;BiN-bO4纳米棒具有较高的光催化活性,在紫外光下,pH值=3.05,催化剂用量为2g/L时能够有效地降解罗丹明B,降解率受到光源、催化剂浓度和溶液pH值的影响较大。
关键词:
共沉淀法
,
BiNbO4纳米棒
,
光催化
杨飒
,
郑志硕
量子电子学报
doi:10.3969/j.issn.1007-5461.2015.03.005
针对尺度不变特征变换(Scale-invariant feature transform,SIFT)算法在关键点特征描述向量阶段计算复杂并且维数较高的现象,提出了一种基于压缩感知理论的SIFT算法.通过压缩感知理论的稀疏特征表示方法,对SIFT关键点特征向量进行提取,将高维梯度导数向量降到低维稀疏特征向量,降低了关键点描述向量维度.采用欧式距离作为关键点的相似性度量, Best-Bin-First(BBF)数据结构避免穷举,使数据的运算量大为减少.实验结果表明,新算法对存在仿射变换的医学图像配准性能优于传统SIFT算法,与当前改进型的SIFT算法相比,本文算法的实时性明显增强.
关键词:
图像处理
,
图像配准
,
尺度不变特征变换
,
特征提取
,
稀疏随机投影
李伟国
,
祁超
,
刘立岩
,
赵大庆
应用化学
doi:10.3969/j.issn.1000-0518.2005.11.003
分别研究了二乙三胺五乙酸(DTPA)及2种衍生物二乙三胺五乙酸-双二甲酰胺(DTPA-BDMA)和二乙三胺五乙酸-双(异烟肼)(DTPA-BIN)对乳酸脱氢酶活性及酶促反应动力学的影响.结果表明,它们均可以抑制脱氢酶的活性,其抑制类型为竞争性的抑制作用,抑制常数分别为3.37、7.41、8.52μmol/L.紫外差谱结果表明,DTPA及其衍生物可以和酶分子作用,其羧基部分被包埋到分子内部,在酶分子的结合部位存在芳香族的氨基酸残基.DTPA与脱氢酶作用后使酶分子中的色氨酸荧光强度减弱,对酪氨酸的荧光没有明显影响.
关键词:
二乙三胺五乙酸
,
乳酸脱氢酶
,
酶学动力学
,
紫外差谱
,
荧光光谱
International Journal of Hydrogen Energy
Electronic structure and the total energy of the Mg(NH(2))(2) were calculated using first principle theory. The bonding characteristics and decomposition mechanism of the Mg(NH(2))(2) were clarified based on the electronic structure and the total energies. The bonding interactions of the Mg atoms with the two [NH(2)] ligands are slightly different, while it shows a significant difference in the bonding interactions between the N and the H atoms within the [NH(2)] ligands. The weakest bond is the N(2)-H(2) bond in the [NH(2))(2) ligand. A decomposition mechanism of the Mg(NH(2))(2) was proposed based on the bonding characteristics. The decomposition of the Mg(NH(2))(2) is performed by two steps. First H(+) cations decompose from the [NH(2)] ligands due to their weaker bonds with the matrix, and then [NH(2)](-) anions decompose. The H(+) cations and [NH(2)](-) anions therefore react each other to generate NH(3). For the Mg(NH(2))(2) + LiH systems, it is most likely that the Mg(NH(2)) decomposes to MgNH, H(+)cation, and [NH(2)](-) anion first, and then the released H(+) cation and [NH(2)]- anion either react each other to form NH(3) and then reacts with LiH, or directly react with Li(+) cation and H(-) anion if LiH is decomposed. Both of the reactions generate the LiNH(2) and the H(2). And the LiNH(2) further mixes with MgNH to form the LiMgN(2)H(3). The is the first step of a multi-step dehydrogenation process of the Mg(NH(2))(2)-LiH system [Isobe S, Ichikawa T, Leng H, Fujii H, Kojima Y. Hydrogen desorption processes in Li-Mg-N-H systems. J Phys Chem Solids 2008;69:22234.]. (C) 2009 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.
关键词:
Magnesium amide;Electronic structure;Decomposition;n-h system;reversible hydrogen-storage;hydride;imides;li3n
