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91.
The mercury(II)-catalysed replacement of cyanide in hexacyanoferrate(II) by p-nitrosodiphenylamine (p-NDA) in aqueous solution has been investigated spectrophotometrically by measuring the change in absorbance of the green complex ion, [Fe(CN)(5).p-NDA](3-), at 640 nm. Activation parameters of the catalysed and uncatalysed reactions have been calculated. The effects of the dielectric constant and water content of the medium on reaction rates are used to explain the formation of a polar activated complex and suggest an I(d) mechanism for the catalysed reaction. The varying catalytic activity of Hg(II) as a function of concentration has been discussed. 相似文献
92.
Terence C. Gibb Robert Greatrex Norman N. Greenwood Kenneth G. Snowdon 《Journal of solid state chemistry》1975,14(2):193-202
The magnetic and structural properties of the solid solution SrFexRu1?xO3?y (0 ? x ? 0.5) have been studied using 57Fe and 99Ru Mössbauer spectroscopy and other techniques. These phases, which are here reported for the first time, have a distorted perovskite structure. The iron substitutes exclusively as Fe3+ and thereby causes oxygen deficiency, but has little effect on the magnetic behaviour of the Ru4+ until x > 0.2, whereupon the metallic band system begins to revert to a localized electron structure. The properties of a sample with x = 0.3 are complex and intermediate in character. For x > 0.3 the oxygen deficiency is reduced by substantial oxidation to Ru5+ until at x = 0.5 the system corresponds to Sr2Fe3+Ru5+O6. 相似文献
93.
Porous SiO2 films were successfully deposited on silicon substrates by a modified base-catalyzed Sol-Gel process (MBCP) containing polyvinyl alcohol (PVA). The process conditions, such as the gelation time, the synthesis temperature, the stabilizing agent of the precursor solution and the spin coating speed, the heat-treatment, the annealing temperature of the film on the microstructure and porosity of porous SiO2 films were systematically investigated by SEM, XRD and ellipsometry techniques. This study provides a novel preparation technique for the porous SiO2 film. Using this process, the resultant film can reach a thickness of 3.6 m for one layer, a porosity of 25–50%, a low thermal conductivity of 0.11 W/m·K. This film will be used as a low dielectric layer, an thermal-insulating layer and a low refractive index layer. 相似文献
94.
A computer algorithm is presented for the simulation of the effect of molecular tumbling on ESR spectra, and is applied to simulation of the conventional ESR signal (the absorption signal detected at the first harmonic of the modulation frequency and in-phase with the modulation frequency, in the limit of low microwave and modulation power) of axially symmetric 14N-nitroxide spin labels. The algorithm is extremely fast and is economical in terms of computer memory requirements. 相似文献
95.
Hexamethylditin in methanol solution reacts rapidly with mercuric chloride to yield mercury and trimethyltin chloride. With alkylmercuric salts the reaction is complex, yielding tetraalkyltin and/or dialkylmercury, depending upon the reactivity of the alkylmercuric salt. An electrophilic substitution mechanism involving trimethylstannyl mercurials as transient intermediates is suggested. The reaction of hexaalkylditin with diarylmercury is suggested to follow a homolyric pathway. 相似文献
96.
Larry I. Shoer Kerrie I. Gell Jeffrey Schwartz 《Journal of organometallic chemistry》1977,136(2):c19-c22
Dialkylaluminum hydrides and Cp2ZrX2 (Cp = π5-C5H5; X = Cl, H, alkyl) were found to react by aggregation to give mixed ZrAl trihydride complexes containing ZrHAl bridges. Reactions of these mixed-metal hydrides are discussed and structural parallels between them and known aluminum hydride complexes are drawn. 相似文献
97.
Jorge Pavez Maritza Páez Armelle Ringuedé Fethi Bedioui José H. Zagal 《Journal of Solid State Electrochemistry》2005,9(1):21-29
We studied the electrocatalytic activity of cobalt tetra-aminophthalocyanine (CoTAPc) for the reduction of molecular oxygen (O2) on adsorbed monomeric and on electropolymerized films of different thicknesses on glassy carbon (GC) electrode. The polymeric films, denoted poly-CoTAPc, were first characterized by electrochemical impedance spectroscopy and it appears that the types of phenomena revealed to be occurring depend less on the film thickness in basic than in acid media. For O2 reduction, the results showed that poly-CoTAPc is more active than the monomeric CoTAPc adsorbed on GC. Indeed, rotating ring-disk electrode data showed that polymeric CoTAPc promotes the four-electron reduction of O2 to water in parallel to a two-electron reduction to give peroxide. On monomeric and thin films of poly-CoTAPc, a two-electron reduction mechanism predominates. In basic media the activity increases very slightly with thickness, whereas in acid media this increase is more pronounced. This parallels the observed behavior revealed by electrochemical impedance spectroscopy. 相似文献
98.
Maxwell A. Cairns Keith R. Dixon Martin A.R. Smith 《Journal of organometallic chemistry》1977,135(1):C33-C34
Syntheses of cis-[PtCl(CH2COCH3)(PEt3)2], cis-[PtCl(CH2NO2) (PEt3)2], and trans-[Pt(CCPh)2 (PEt3)2] are described. The procedure involves reaction of cis-[PtCl2(PEt3)2] with Ag2O and acidic CH bonds to precipitate AgC1 and generate a PtC bond. The method may represent a new general route to platinum—carbon bonds. 相似文献
99.
This work describes the use of a dual-standard analysis approach termed the time-average ratio (TAR) in affinity capillary electrophoresis (ACE) to estimate binding constants of receptors to ligands. In this form of analysis the TAR is the migration time of the receptor divided by the average of the sum of the migration times of two non-interacting standards. This change in TAR as a function of the concentration of ligand yields a value for the binding constant. This concept is demonstrated using three model systems: carbonic anhydrase B (CAB, EC 4.2.1.1) and arylsulfonamides, vancomycin (Van) and ristocetin (Rist) from Streptomyces orientalis and Nocardia lurida, respectively, and d-Ala- d-Ala terminus peptides. Three ACE techniques are used to examine the three systems: standard ACE, flow-through partial-filling ACE (FTPFACE), and on-column derivatization coupled to ACE. The findings described here demonstrate that ACE data analyzed using the TAR form of analysis yield binding constants between receptors and ligands comparable to those estimated using other ACE forms of analysis. A comparison to three other forms of analysis is described. 相似文献
100.
孙诒让的《墨子间诂》被王焕镳誉之为“墨学研究中的旷代之作”,又被罗检秋称为“墨学发展史上的一个重要里程碑”。它继承吸取了20世纪以前墨学研究的成果,基本恢复了《墨子》文本的真实面目,为墨学思想的研究和现代价值的挖掘铺平了道路,扫清了障碍,促进五四时期墨学科学价值的被发现和平民学说、逻辑价值的确立,以至引来20世纪30至60年代墨学研究的全面丰收,最终促成墨学的伟大复兴。 相似文献