997 resultados para 193-1191
Resumo:
Twelve mediators have been modified by adsorption onto the paraffin impregnated graphite electrodes (IGE). The resulting electrodes exhibit electrocatalytic activity of different degrees towards oxidation of 1,4-dihydronicotinamide adenine dinucleotide (NADH). The electrocatalytic ability of the chemically modified electrode (CME) depends mainly on the formal potential and molecular structure of mediator. The formation of the charge transfer complex between NADH and adsorbed mediator has been demonstrated by the experiments using a rotating disk electrode. An electrocatalytic scheme obeying Michaelis-Menten kinetics has been confirmed, and some kinetic parameters were estimated. The solution pH influences markedly the electrocatalytic activity of the modified electrode. Various possible reasons are discussed.
Resumo:
The ESR of PPy films doped with Co (W2O7)(6)(10-) and CuW12O406- ions were reported and discussed. Results show that heteropolyanions not only play the role of neutralizing electricity in the PPy film, but also interact with the PPy molecular chain to form some adducts. The adducts affect the electronic structure of the PPy film and are unstable at more positive or more negative potentials. Dysonian ESR lineshape was recorded for the dry PPy film with CuW12O406- for the first time.
Resumo:
本文通过对不同条件下的Co(W_2O_7)_6~(10-)和CuW_(12)O_(40)~(6-)掺杂聚吡膜ESR谱线的分析并以相同条件下NO_3~-掺杂聚吡咯膜作为参照,表明杂聚阴离子不仅起着中和电性的作用,而且与聚吡咯分子链相作用形成某种加合物,它影响聚吡咯的电结构,这种加合物在过正或过负的电位下均不稳定.首次发现在CuW_(12)O_(40)~(6-)掺杂的干态聚吡咯膜具有Dysonian线型,表明膜中其它电结构的存在.
Resumo:
随着稀土资源的不断开发利用,它们不可避免地通过多种途径进入生物体内,因而从分子和细胞水平上研究稀土的生物效应具有非常重要的理论和实际意义.关于稀土与细胞作用的研究已有诸多报道,本文报道用~(133)Cs NMR方法研究La~(3+)对Cs~+跨膜进入红细胞的影响.对于物质跨膜传输的研究,首先需要合适的手段将被传输物质在膜两侧的分布区分开.在碱金属离子中,仅~(133)Cs~+在不引入顺磁位移试剂情况下,细胞内外NMR信号能确切区分,并且在体系中无K~+时,Cs~+有类似于K~+的功能,故~(133)Cs是研究稀土离子与细胞作用
Resumo:
本文研究了四种具有Keggin结构的杂多酸在五种国产改性活性炭载体上的吸附作用.实验结果表明,不同的杂多酸在活性炭上的吸附量是不同的,并且不同的活性炭对杂多酸的吸附等温线和吸附能力也不同.活性炭的表面化学性质显著地影响杂多酸在其上的吸附。
Resumo:
首次合成了二价铕中性芳烃配合物[Eu(C6Me6(AlCl4)2]·Me4C6H2,并经红外光谱,激发光谱和荧光光谱表征,测定了晶体结构。配合物属单斜晶系,P2/c空间群,晶胞参数a=1.7652(4)nm,b=1.5918(4)nm,c=1.8752(5)nm;β=97.61(5)°,Z=2,R=0.0496,Rw=0.0462。
Resumo:
All the members of the solid solution of YSr2-xCaxV3O9-y have the orthorhombic symmetry. Their electrical and magnetic properties have been studied. The magnetic susceptibility and electrical resistivity increase gradually with x. The system shows paramagnetic behavior both at 300 K and at 77 K. It is shown that a change of valence state of vanadium obviously affects the electrical and magnetic properties of the solid solution.