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排序方式: 共有268条查询结果,搜索用时 15 毫秒
1.
V. V. Panić A. B. Dekanski S. K. Milonjić V. B. Mišković-Stanković B. Ž. Nikolić 《Russian Journal of Electrochemistry》2006,42(10):1055-1060
Electrocatalytic properties of RuO2/Ti anode with different coating masses, which are prepared by the alkoxide sol-gel procedure, are investigated in chlorine
and oxygen evolution reactions by polarization measurements and electrochemical impedance spectroscopy in H2SO4 and NaCl electrolytes. According to polarization measurements, the activity of anodes at overpotentials below 100 mV is independent
of coating mass. However, impedance measurements above 100 mV reveal changes in the activity of anodes in chlorine evolution
reaction for different coating masses. The diffusion limitations related to the evolved chlorine are registered in low-frequency
domain at 1.10 V (SCE), diminishing with the increase in potential to the 1.15 V (SCE). The observed impedance behavior is
discussed with respect to the activity model for activated titanium anodes in chlorine evolution reaction involving formation
of gas channels within porous coating structure. Gas channels enhance the mass transfer rate similarly to the forced convection,
which also increases the activity of anode. This is more pronounced for the anode of greater coating mass due to its more
compact surface structure. The more compact structure appears to be beneficial for gas channels formation.
Published in Russian in Elektrokhimiya, 2006, Vol. 42, No. 10, pp. 1173–1179.
The text was submitted by the authors in English. 相似文献
2.
On the Harary index for the characterization of chemical graphs 总被引:1,自引:0,他引:1
3.
The construction of the Z-counting polynomial for edge-weighted graphs is discussed.Dedicated to Professor Haruo Hosoya (Tokyo) on the occasion of his 55th birthday for enriching chemical graph theory with the elegant concept of the Z-counting polynomial. 相似文献
4.
The absorption spectra of Co(II) chloride complexes, containing variable concentrations of chloride ligand, in a molten mixture of 80 mol% acetamide–20 mol% calcium nitrate tetrahydrate, were studied at 313, 333, 353, and 363 K, in the wavelength range 400-800 nm. The melt contains three possible ligands (CH3CONH2, H2O, and NO3
-) for competition with added chloride ligand. Addition of chloride caused a shift of the absorption maximum of octahedral cobalt(II) nitrate towards lower energies and pronounced changes in the shape of the initial spectrum of cobalt(II) nitrate. The effect of temperature changes on the molar absorption coefficient of the Co(II) species was dependent on the chloride concentration and was attributed to the structural changes occurring in the cobalt(II) species. The STAR and STAR FA programs were applied to identify the complex ionic species and to calculate the stability constants of Co(II) complexes formed in this solvent. The results indicate the highest probability of formation of the following complex species: Co(NO3)4
2-, Co(NO3)2Cl2
2-, and CoCl4
2-. Stability constants of each complex were presented for the equilibria occurring at 313, 333, 353, and 363 K. Distribution of the Co(II) species was also calculated over the ranges of chloride concentration and temperature investigated. 相似文献
5.
P. M. Nikolić Lj. Milković P. Mihajlović B. Lavrenčić 《Czechoslovak Journal of Physics》1978,28(4):456-459
Zone center optical phonons in SnSe were investigated using Raman scattering data obtained here and previously reported far infrared reflectivity measurements. The values of the ratio of the pairs of interlayer force constants were calculated te be between 3·3 and 4·5. Thus it can be concluded that SnS is a layer like semiconductor but less layer like than GeS, GeSe or SnS. 相似文献
6.
The excitation and emission luminescence spectra of the complex compounds of manganese (II) chloride with the hydrochlorides of pyridine, 2-methyl- and 2-ethylpiperidine have been studied. It has been established that the crystals of these complex compounds appear in tetrahedral and octahedral configurations. The excitation spectra in both configurations contain bands originating from the4G,4P,4D and4F terms, the position of which is determined by configuration. From the excitation spectra the Racah parametersB andC and the ligand field strength parameter 10Dq have been determined.The emission luminescence spectra also depend on configuration of the complex compound. The character of these spectra is expressed in terms of the following characteristic parameters: the position of the maximum of the functionG(v), the half-width of the emission luminescence band, and the constants andm. From the excitation and emission luminescence spectra it has been established that the emission in both configurations is due to the4T1(G)6A1 transition. 相似文献
7.
Summary The semiquantitative determination of micro amounts of pyrocatechol, resorcinol, hydroquinone, pyrogallol, phloroglucinol, andp-nitrophenol using the Weisz ring colorimetry method has been described. The results obtained deviated, on an average, from those calculated by about 4% and the amount of phenol required for one determination was about 4 g.
Zusammenfassung Die halbquantitative Bestimmung von Mikromengen Brenzcatechin, Resorcin, Hydrochinon, Pyrogallol, Phloroglucin und p-Nitrophenol mit Hilfe der vonWeisz angegebenen Ringkolorimetrie wurde beschrieben. Die Resultate weichen von den berechneten Werten durchschnittlich um etwa 4% ab, wobei für eine Bestimmung etwa 4 g benötigt werden.
Résumé On décrit le dosage semiquantitatif de microquantités de pyrocatéchol, résorcinol, hydroquinone, pyrogallol, phloroglucinol etp-nitrophénol, à l'aide de la méthode colorimétrique annulaire deWeisz. Les résultats obtenus se sont écartés, en moyenne, d'environ 4% d'avec ceux calculés et la quantité de phénol nécessaire pour un dosage s'élevait à 4 g environ.相似文献
8.
In the present paper, a new approach was developed for solving the problem of time synchronization of a set of signals obtained by different measurement techniques without a common trigger. The recorded signals were the result of sparks and bursts generated by a repetitive Marx generator. A thermal imaging camera, a high speed camera and an audio recorder were used to obtain the necessary data for synchronization and characterization. Moreover, a piezoelectric sensor was applied for shock waves characterization during the early stages of bursts. In the first place, different data with evident time shifts were acquired. Then, A set of simple operations such as maximum selection and localization, threshold comparison, Euclidean distance calculation and minimization were employed for signal analysis and pattern matching to ensure a good data synchronization, which allowed a detailed analysis of the phenomenon in the end. 相似文献
9.
Application of Novel Zn‐Ferrite Modified Glassy Carbon Paste Electrode as a Sensor for Determination of Cd(II) in Waste Water 下载免费PDF全文
Dalibor M. Stanković Sandra Škrivanj Nenad Savić Aleksandar S. Nikolić Predrag Vulić Dragan D. Manojlović 《Electroanalysis》2014,26(7):1536-1543
This paper describes the preparation of a new sensor based on Zn‐ferrite modified glassy carbon paste electrode and its electrochemical application for the determination of trace Cd(II) ions in waste waters using differential pulse anodic stripping voltammetry (DPASV). Different Zn/Ni ferrite nanoparticles were synthesized and characterized using scanning electron microscopy (SEM) and X‐ray powder diffraction (XRPD). The prepared ferrite nanoparticles were used for the preparation of Zn‐ferrite‐modified glassy carbon paste electrode (ZnMGCPE) for determination of Cd(II) at nanomolar levels in waste water at pH 5. The different parameters such as conditions of preparation, Zn2+/Ni2+/Fe2+ ratio and electrochemical parameters, percentage of modifier, accumulation time, pH and accumulation potential were investigated. Besides, interference measurements were also evaluated under optimized parameters. The best voltammetric response was observed for ZnFe2O4 modifier, when the percentage of modifier was 3 %, accumulation time 9 min, pH of supporting electrolyte 5 and accumulation potential ?1.05 V. Thus prepared electrode displays excellent response to Cd(II) with a detection limit of 0.38 ppb, and selective detection toward Cd(II) was achieved. 相似文献
10.
Pure states in quantum field theory can be represented by many-fingered block-time wave functions, which treat time on an equal footing with space and make the notions of “time evolution” and “state at a given time” fundamentally irrelevant. Instead of information destruction resulting from an attempt to use a “state at a given time” to describe semi-classical black-hole evaporation, the full many-fingered block-time wave function of the universe conserves information by describing the correlations of outgoing Hawking particles in the future with ingoing Hawking particles in the past. 相似文献