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排序方式: 共有124条查询结果,搜索用时 15 毫秒
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Ahmed Galal Soher A. Darwish Rasha A. Ahmed 《Journal of Solid State Electrochemistry》2007,11(4):521-530
Conducting polymers were deposited on the surface of platinum and glassy carbon electrodes. The monomers used were N-methyl pyrrole and 3-methyl thiophene. The electrochemical synthesis of the polymer was achieved using constant applied potential
or cyclic polarization techniques in acetonitrile as a solvent and tetra-alkyl ammonium salts as supporting electrolyte. The
resulting conducting polymeric film was modified with an inorganic metal complex, namely, Cu–phthalocyanine or Co–phthalocyanine.
Two different approaches were adopted for the modification: (1) the first was to directly apply the metal–phthalocyanine layer
on the surface of the polymer, and (2) the second was by the inclusion of the metal–phthalocyanine in a sol–gel matrix that
was in turn applied to the conducting polymer film. In the first part of this work, we studied the effect of changing the
type of polymer matrix and the central metal of the inorganic complex on the electrochemical behavior of the resulting film.
We also found that changing the method of metal–phthalocyanine application to the polymer film affected the electrochemical
response and kinetics at the electrode surface. The new electrode was tested for the reduction of hydrogen peroxide and showed
better conversion efficiency compared to conventional surfaces, which suggests its use in fuel cell applications. 相似文献
34.
Simple Zeros of the Riemann Zeta-Function 总被引:1,自引:0,他引:1
Assuming the Riemann Hypothesis, Montgomery showed by meansof his pair correlation method that at least two-thirds of thezeros of Riemann's zeta-function are simple. Later he and Taylorimproved this to 67.25 percent and, more recently, Cheer andGoldston increased the percentage to 67.2753. Here we proveby a new method that if the Riemann and Generalized LindelöofHypotheses hold, then at least 70.3704 percent of the zerosare simple and at least 84.5679 percent are distinct. Our methoduses mean value estimates for various functions defined by Dirichletseries sampled at the zeros of the Riemann zeta-function. 1991Mathematics Subject Classification: 11M26. 相似文献
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Ahmed Galal 《Journal of Solid State Electrochemistry》1998,2(1):7-15
Conducting poly(3-methylthiophene) electrodes were electrochemically prepared. The resulting polymer films were modified
with an inorganic complex, ferrocene. The incorporation of the ferrocene/ferrocenium moiety into the polymer film resulted
in enhanced charge transfer towards the oxidation of some organic molecules of biological interest. The electrochemical response
of the complex-containing polymer electrode was compared to that of the unmodified polymer electrode and that of the substrate.
Apparent diffusion coefficients of the redox species were estimated from the cyclic voltammetric data for different biological
molecules at the ferrocene-containing polymer electrode. Infra-red spectroscopic measurements for the “as-grown” films revealed
the presence of the inorganic complex within the polymer. The modified polymer electrode showed noticeable enhancement for
the charge transfer across the film interface and can be used as an electrochemical sensor for biological compounds.
Received: 3 June 1997 / Accepted: 7 July 1997 相似文献
37.
Maisa I. Abdel Moneam Ahmed A. Geies Galal M. El‐Naggar Soliman M. Mousa 《中国化学会会志》2004,51(6):1357-1366
Sodium salt of 4‐hydroxy‐6‐methyl‐2‐phenylpyrimidine‐5‐carbonitrile ( 3 ) was subjected to alkylation with different a‐halo compounds, where the corresponding O‐alkylated products 4a‐g were obtained. Ring closure of the O‐alkylated product 4a‐c performed using sodium ethoxide in refluxing ethanol afforded furo[2,3‐d]pyrimidines 5a‐c The latter compounds on reaction with a variety of reagents gave other new furopyrimidines as well as a number of furodipyrimidines. 相似文献
38.
Emad M. El-Telbani Mohamed F. El Shehry Galal A. M. Nawwar 《Monatshefte für Chemie / Chemical Monthly》2008,139(6):685-689
Synthesis of the title ring system is described using ethyl 4-(2,4-dichlorophenoxy)-3-oxobutanoate as starting material. The
latter was prepared through acylating Meldrum’s acid with the phenoxy acid chloride derivative.
Correspondence: Emad M. El-Telbani, Pesticides Department, National Research Centre, Dokki, 12622 Cairo, Egypt. 相似文献
39.
Quantum Zeno and anti-Zeno paradoxes 总被引:1,自引:0,他引:1
Continuous observation of a time independent projection operator is known to prevent change of state (the quantum Zeno paradox).
We discuss the recent result that generic continuous measurement of time dependent projection operators will in fact ensure
change of state: an anti-Zeno paradox. 相似文献
40.