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31.
It is often numerically convenient to reduce models in two-dimensions to one-dimension. This can be done formally through the use of centre manifold techniques, or informally using physical reasoning. We investigate the extent to which flammability limits in a two-dimensional slab are accurately represented by the values in the corresponding one-dimensional slab. We use a simple chemical mechanism containing exothermic and endothermic reactions that has been used to model the combustion of hydrocarbon fragments produced by polymer pyrolysis. 相似文献
32.
s-Triazolo[3,4-a]isoquinoline (II) and its 3-methyl analogue (III) have been synthesized from 1-isoquinolylhydrazine (I) by cyclisation with formic and acetic acid. The 3-hydroxy derivative (IV) has been shown to exist in the lactam form. Methylation with methyl iodide gave the N-methyl derivative (V). Dimethyl sulphate and diazomethane also led exclusively to the same product. The O-methyl derivative (IX) could be obtained only through the 3-chloro compound (VIII). The chlorine atom in VIII undergoes nucleophilic replacement easily. The 3,6-dichloro derivative (X) has also been prepared. Several interconversions in the series are described. Aryl hydrazones (XVIII) prepared from (I) have been oxidatively cyclised to give 3-aryl-s-triazolo[3,4-a]isoquinolines (XIX). U.V., I.R. and P.M.R. spectra have been recorded and used for assignment of structures in some cases. 相似文献
33.
A new and convenient colorimetric method for determination of carbon disulphide, based on its transformation into bright yellow potassium benzyl trithiocarbonate through reaction with benzyl mercaptan and potassium hydroxide in tert.-butyl alcohol, has been successfully applied to determination of some dithiocarbamate fungicides in their formulations. The method possesses a distinct advantage in that it is free from all sources of errors/problems which are associated with the xanthate method for the analysis of these materials. The proposed method is precise and accurate and hence recommended for routine analysis of technical formulations containing dithiocarbamate fungicides. 相似文献
34.
Seema Kanwar 《合成通讯》2013,43(16):2149-2155
Abstract α‐Cyano and α‐chloro β‐lactams are obtained in a one‐step reaction at a temperature of less than ?78°C by condensation of imines with ester enolates derived from ethyl α‐cyano and α‐chloro acetates. 相似文献
35.
In this paper, we derive one-parameter families of Newton, Halley, Chebyshev, Chebyshev-Halley type methods, super-Halley,
C-methods, osculating circle and ellipse methods respectively for finding simple zeros of nonlinear equations, permitting
f ′ (x) = 0 at some points in the vicinity of the required root. Halley, Chebyshev, super-Halley methods and, as an exceptional
case, Newton method are seen as the special cases of the family. All the methods of the family and various others are cubically
convergent to simple roots except Newton’s or a family of Newton’s method.
相似文献
36.
Sardool S. Ghumman Rajender Singh N. P. S. Sidhu H. S. Sahota 《Journal of Radioanalytical and Nuclear Chemistry》1987,118(6):433-436
The perturbed angular correlation /P.A.C./ technique is employed to investigate the structures of barium ferrite and barium hexaferrite using radioactive133Ba /10.7 Y/ as a probe. The quadrupole interaction frequencies /WQ'S/ are found to be 9.68 and 12.02 Mrad sec–1 for barium ferrite and barium hexaferrite, respectively, showing a drift from usual cubic structure. 相似文献
37.
Time-resolved transient absorption spectra have been observed using monochromatic light (=347.1 nm) from a 25 ns pulsed ruby laser. Collision between optically excited uranyl ion and ditertiary phosphines lead to photochemical reduction of uranyl ion to uranium(V) in non-aqueous medium. Stern-Volmer constants measured from lifetime measurement and quantum yields for uranium(V) formation reveal that electron transfer phenomenon competes with photophysical deactivation because of the presence of phenyl groups. Since ditertiary phosphines have two electron donating phosphorus atoms, are better reductant than monodentate phosphines in non aqueous medium. 相似文献
38.
H. P. S. Bhandari G. Lal N. P. S. Sidhu V. K. Mittal H. S. Sahota 《Journal of Radioanalytical and Nuclear Chemistry》1987,119(5):379-385
Unlike previously reported Zn and Se levels were found to be the same in the hair of mentally retarded children and controls. Non-essential toxic Ag concentration was low whereas that of Hg, Au and Sc rather high in mentally retarded children. 相似文献
39.
Summary A method is described for the determination of mercaptans by alkalimetric titration of trithiocarbonic acids formed through their reaction with carbon disulphide in tert.-butanol. The method has been applied to the analysis, on the same sample solution, of mixtures of mercaptans containing titrable hydrogen and those containing nontitrable hydrogen, mercaptans and alkali mercaptides, and mercaptans and mercaptopyrimidines.
Analytische Anwendung der Merkaptan-Schwefelkohlenstoff-Reaktion: Bestimmung von Merkaptan in Gemischen
Zusammenfassung Ein Verfahren zur Merkaptanbestimmung durch alkalimetrische Titration der Trithiokohlensäure auf der Grundlage seiner Reaktion mit Schwefelkohlenstoff in tert. Butanol wurde beschrieben. Es eignet sich zur Bestimmung von Gemischen aus Merkaptanen mit titrierbarem Wasserstoff und solchen ohne titrierbaren Wasserstoff sowie von Merkaptanen und Merkaptiden, weiters von Merkaptanen und Merkaptopyrimidinen.相似文献
40.
We investigate a chemostat model in which the growth rate is given by a Monod expression with a variable yield coefficient.
This model has been investigated by previous researchers using numerical integration. We combine analytical results with path-following
methods. The conditions for washout to occur are found. When washout does not occur we establish the conditions under which
the reactor performance is maximised at either a finite or infinite residence time. We also determine the parameter region
in which oscillations may be generated in the reactor, which was the primary feature of interest to earlier workers on this
problem. 相似文献