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991.
Arben Merkoçi Majlinda Vasjari Esteve Fàbregas Salvador Alegret 《Mikrochimica acta》2000,135(1-2):29-33
Two different approaches for the modification of glassy carbon electrodes using a mercury film and mercury-nafion are compared.
The mixture of mercury(II) chloride solution with a nafion solution diluted in ethanol is used to coat the polished glassy
carbon surface. The modified working electrodes are compared when measuring Pb and Cu in real seawater samples. An optimisation
of the parameters during the formation of the films was done to obtain well-defined stripping peaks. The type of inert supporting
electrolyte and the pH play an important role on the sensitivity of the measurement. Results for Pb and Cu determinations
show the advantages of Hg-nafion modification as an alternative method. These advantages include a shorter modification time,
the avoidance of Hg solutions during the formation of the Hg film and an improved sensitivity for Pb determination.
Received March 16, 1999. Revision April 24, 2000. 相似文献
992.
993.
The southern γ-butyrolactone subunit 8 of polycavernoside A was readily assembled by a novel and connective methodology involving an initial ene-reaction followed by an intramolecular oxidative cyclisation. 相似文献
994.
N. Aksel 《Archive of Applied Mechanics (Ingenieur Archiv)》2000,70(1-3):81-90
Summary In creeping flows of thin films, the capillarity can play a dominant role. In this paper, the creeping film flow down an
inclined plane with an edge is considered. The influence of the capillarity on the velocity and the film surface is studied
analytically, numerically and experimentally.
Received 12 April 1999; accepted for publication 9 May 1999 相似文献
995.
Ce-substituted BiFeO3 film (BCFO film) have been prepared by sol–gel process on F doped SnO2 (FTO)/glass substrates. The effects of Ce substitution on the structural and electrical properties have been reported. X-ray
diffraction data confirmed the R3c structure with the elimination of all secondary phases. We observed an increase in the
remnant polarization (Pr) with Ce substitution and obtained a maximum value of ∼84 μC/cm2 in 5% Ce-substituted film. The dielectric constant of the films was increased from 280 to about 420 for the BiFeO3 film and 5% Ce-substituted BCFO film, respectively and the films showed excellent dielectric loss behavior. Moreover, the
leakage current was substantially reduced by the Ce substitution. 相似文献
996.
A. Agui A. Asahi J. Sayama M. Mizumaki M. Tanaka T. Osaka 《Journal of magnetism and magnetic materials》2008
Magnetic circular dichroism (MCD) and X-ray absorption spectra (XAS) at the Co L2,3-edge of [Co/Pd]20 and [CoB/Pd]20 multilayered films, which were fabricated at 260 °C with different magnetic layer thicknesses (δ), have been measured. The lineshapes of XAS–MCD show that the electronic state of Co 3d of the films hardly changes even when sputtered at higher temperatures. The expectation values of orbital and spin angular momentum (〈Lz〉 and 〈Sz〉) are estimated using the sum rule, and it is found that 〈Lz〉/〈Sz〉 in δ<0.5 nm is larger than that in δ>0.5 nm. 相似文献
997.
This paper uses the moiré interferometry of sticking film in synchronous measurement of 2-D displacements for determining the stress intensity factors of mixed mode. The calculating formula of mixed mode SIF of a beam with an oblique crack has been derived, which can be applied to the general cases in 2-D questions of mixed mode crack. This result is of extensive value for application to engineering questions that has no analytic solutions and numerical value solutions.Projects Supported by Foundation of Natural Sciences of China. 相似文献
998.
新型杂多酸[Bu4N][Ni(pph3)2]PW11O39硅溶胶修饰电极电化学性质及电催化研究 总被引:2,自引:0,他引:2
采用溶胶-凝胶技术制备了新多金属氧酸盐[Bu4N][Ni(pph3)2]PW11O39(Bu为四丁基,pph为苯基磷)有机-无机杂化材料修饰电极,该修饰电极不仅保持了本体溶液的电化学和电催化性质,而且还具有很好的稳定性与灵敏度.研究表明,优选条件下修饰电极在pH=4.5的缓冲溶液中,其催化电流与NO2-浓度在6.0×10-6~1×10-3mol/L范围内呈良好的线性关系,对不同基质环境水样的加标回收率为97%~102%,方法的检出限为1.0×10-7mol/L,对1.0×10-4mol/L NO2-平行测定10次的相对标准偏差(RSD)为1.96%. 相似文献
999.
Monomeric tungsten oxo‐aminoalkoxides W(O)(OPri)3(L) [L = O(CH2)nNMe2; n = 2 (dmae, 1) and 3 (dmap, 2 )] were synthesized by alcohol exchange with [W(O)(OPri)4]2 and characterized spectroscopically. 1, 2 and [W(O)(OPri)4]2 were used as precursors for the aerosol‐assisted chemical vapour deposition of WO3 thin films, which were characterized by glancing angle X‐ray diffraction, SEM and transmission‐reflectance measurements. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
1000.
A new carbon‐based mercury thin‐film electrode consisting of screen‐printed carbon on a low temperature co‐fired ceramic substrate was made. Ex‐situ mercury deposition in a potassium thiocyanate solution was used. This approach an electrode with high long‐term stability (>500 measurement cycles) and reproducibility (≤2 %) for sensitive determination of ultra trace heavy metals, using differential pulse anodic stripping voltammetry. The detection limits were 0.25, 0.08 and 5.5 ng mL?1 for Cd(II), Pb(II), and Zn(II), respectively. The method was applied to the determination of the analytes in water, wastewater, lake water, and certified reference material samples with satisfactory results. 相似文献