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201.
The structure of [Pt2Cl(CO) (μ-Ph2PCH2PPh2)2] [PF6] was determined by -ray methods and refined to = 0.082, using diffractometric intensities of 5646 independent reflections. The crystals are monoclinic, space group 21/, = 12.919(3), = 15.576(6), = 25.151(5)Å, β = 94.82(3)°, = 4. They are built of octahedral hexafluorophosphate anions and dinuclear platinum(I) cations. The latter contain PtCl and PtCO fragments linked to one another by a PtPt σ-bond and by two bridging bis(diphenylphosphino)methane ligands. The platinum atoms are in square planar environments and the dihedral angle between the two coordination planes is 40.1°. Selected bond lengths are: PtPt 2.620(1), PtCl 2.384(5), PtC 1.89(3) and PtP 2.291(5) – 2.308(5)Å. 相似文献
202.
Nj. Radić 《Mikrochimica acta》1985,85(3-4):209-218
Summary The preparation and performance of an Hg(II)-ISE are described. The analytical behaviour of this electrode, made by chemical treatment of a commercial silver sulphide type Pb(II)-ISE, is discussed in terms of potentialvs. concentration curves, potentialvs. pH curves, and selectivity. The response to fixed cHg(II) as the pH is increased in the alkaline region corresponds to decrease in the free Hg2+concentration down to pHg 17. The estimated limit of detection of total Hg(II) concentration is 10–5
M.
Presented at the Fifth European Conference on Analytical Chemistry (EUROANALYSIS-V), Cracow, Poland, 26–31 August, 1984. 相似文献
Potentiometrisches Verhalten einer handelsüblichen (Ag2S+PbS)-Membran-Elektrode gegenüber Hg(tt) in wäßriger Lösung
Zusammenfassung Herstellung und Wirkungsweise einer gegen Hg(II) ionenselektiven Elektrode wurde beschrieben. Das analytische Verhalten dieser Elektrode, die sich durch chemische Behandlung einer handelsüblichen Silbersulfidelektrode, die für Pb(II)-Ionen selektiv ist, herstellen läßt, wurde an Hand von Potential-Konzentrationskurven, Potential-pH-Kurven und ihrer Selektivität diskutiert. Das Verhalten gegenüber fixemc Hg(ii)bei Anstieg des pH ins alkalische Gebiet korrespondiert mit der Abnahme der Konzentration an freien Hg2+-ionen bis herab zu pHg 17. Die Nachweisgrenze liegt schätzungsweise bei einer totalen Hg(II)-Konzentration von 10–5 M.
Presented at the Fifth European Conference on Analytical Chemistry (EUROANALYSIS-V), Cracow, Poland, 26–31 August, 1984. 相似文献
203.
A method for quantitative determination of uranium in phosphoric acid and wet phosphoric acid has been developed. After reduction with Fe, uranium(IV) is extracted with a kerosene solution of octylphenylphosphoric acid. The uranium was stripped with 10M H3PO4, containing H2O2, and then determined spectrophotometrically with Arsenazo III and by direct uranium(IV)-phosphoric acid solution measurements. 相似文献
204.
Ilija Lukačević 《General Relativity and Gravitation》1983,15(6):523-533
Two vector fields are considered, a timelike one,u
, and an arbitrary one, . The relative expansion and rotation are defined with respect to these fields, their mutual relations are studied, and some general formulas obtained. Applications are made, first to vector fields which are mutually nonrotating in a plane-symmetric metric, then to the electromagnetic field of an arbitrary magnetohydrodynamic fluid. 相似文献
205.
Summary Research was carried out to determine conditions for the anodic generation of manganese(III) with high current efficiency in solutions of sodium perchlorate in acetic acid, and to examine the behaviour of the oxidant thus generated. The effects of water and acetic anhydride on current efficiency in the generation of the oxidant was also examined. The formal redox potential of the Mn(III)/ Mn(II) system is decreased with increasing concentrations of sodium acetate in the solution. The effect of sodium perchlorate and perchloric acid concentrations is the reverse. Procedures for coulometric titrations of a number of substances with the generated oxidant were developed, end point being detected using biamperometric and potentiometric methods. Perchloric acid accelerates the oxidation of certain substances with manganese(III) in acetic acid and increases the sensitivity of end-point detection using the potentiometric method.
Presented at the 9th International Symposium on Microchemical Techniques, Amsterdam, August 28–September 2, 1983. 相似文献
Elektrochemische Erzeugung von Mangan(III) und das Verhalten dieses Oxydationsmittels in Essigsäure bei Gegenwart von Perchlorat
Zusammenfassung Die Bedingungen der anodischen Erzeugung von Mangan(III) mit hoher Stromausbeute in Essigsäure, nach Zugabe von Natriumperchlorat wurden untersucht; das elektrochemische Verhalten des so dargestellten Oxydationsmittels wurde ebenfalls untersucht. Der Einfluß von Wasser und Essigsäureanhydrid auf die prozentuelle Stromausbeute des erwähnten Oxydationsmittels wurde verfolgt. Das Formalredoxpotential des Systems Mn(III)/ Mn(II) sinkt bei Erhöhung der Konzentration an Natriumacetat in der Lösung. Perchlorsäure wie auch Natriumperchlorat üben eine entgegengesetzte Wirkung aus und führen zur Steigerung des Formalredoxpotentials bei Erhöhung ihrer Konzentration. Verfahren zur coulometrischen Titration verschiedener Substanzen mittels biamperometrischer oder potentiometrischer Erfassung des Titrationsendpunktes wurden ausgearbeitet. In Gegenwart von Perchlorsäure wächst die Geschwindigkeit der Oxydation einiger Substanzen in Essigsäure in Gegenwart von Mn(III) und auch die Empfindlichkeit der Endpunktbestimmung verbessert sich.
Presented at the 9th International Symposium on Microchemical Techniques, Amsterdam, August 28–September 2, 1983. 相似文献
206.
Nenad Trinajstić 《Journal of mathematical chemistry》1990,5(2):171-175
A novel classification scheme for polyhex hydrocarbons is proposed. 相似文献
207.
Cheng Y Huang Q Eić M Balcom BJ 《Langmuir : the ACS journal of surfaces and colloids》2005,21(10):4376-4381
We present the first 13C magnetic resonance imaging study of CO2 transient adsorption/desorption processes in a zeolite 5A column. CO2 transient concentration profiles were measured with a centric scan spin-echo single point imaging technique. The adsorption wave profiles were determined under flow conditions, with the results analyzed by the Bohart-Adams model. The model adequately accounts for the spatial and the temporal behavior of CO2 in the column. CO2 adsorption rate constants were calculated from the fit. Desorption profiles were acquired by blowing a helium stream through a zeolite 5A column saturated with CO2. An asymmetry between the adsorption and desorption profiles is readily apparent. A linear relationship between the CO2 condensed phase concentration and square root of time was observed. 相似文献
208.
209.
Analyzing a gliadin extract by matrix assisted laser desorption/ionization-time of flight-mass spectrometry (MALDI-TOF-MS) combined with an artificial neural network (ANN) is a suitable method for identification of wheat varieties. However, the ANN can not distinguish between all different wheat varieties. Two-dimensional polyacrylamide gel electrophoresis (2-D PAGE) was applied to three pairs of wheat varieties, which can not be classified correctly by ANN. By 2-D PAGE the varieties in the three pairs can be discriminated and these six wheat varieties can be separated from each other, which could not be separated by MALDI-TOF-MS and NN. 相似文献
210.
Skorić I Basarić N Marinić Z Visnjevac A Kojić-Prodić B Sindler-Kulyk M 《Chemistry (Weinheim an der Bergstrasse, Germany)》2005,11(2):543-551
New heteroaryl-substituted o-divinylbenzenes, 2,2'-(1,2-phenylenedivinylene)difuran (9), 2,2'-(1,2-phenylenedivinylene)bisbenzo[b]furan (10), and 2,2'-(1,2-phenylenedivinylene)bisnaphtho[2,1-b]furan (11), were prepared and irradiated at various concentrations; intramolecular photocycloaddition and intermolecular [2+2] twofold photoaddition reactions took place to give bicyclo[3.2.1]octadiene derivatives 12-14 and cyclophane derivatives 15-17, respectively. Compound 11 was the most selective of these o-divinylbenzenes, which, owing to pi-pi intra- or intermolecular complexation, gave only the exo-bicyclo[3.2.1]octadiene derivative 14 at low concentrations, and only the cyclophane derivative 17 at high concentrations. 相似文献