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1.
An investigation of the possibilities for the direct determination of calcium with a single-cell filter flame photometer, without preliminary separation as oxalate, led to the following conclusions:Calibration curves for 100 p.p.m. of calcium are rectilinear.Sodium causes an appreciable positive error.The error due to potassium interference is relatively much smaller than that due to sodium. Up to a certain concentration it is positive and increases with the concentration, then the emission seems to be gradually depressed and the error finally becomes negative.Phosphates cause a very significant negative error, which tends to be asymptotic. The “radiation buffer” method of correction is not practical here because the max. error is too high (—92.5%).Except for extreme cases, calcium can be determined by direct spraying, without preliminary separation as oxalate: (a) in drinking and irrigation water, correction being necessary only for sodium interference, (b) in soil extracts, correcting only for phosphate effects, (c) in normal blood sera, without clinically significant corrections at 1+3 dilution.Owing to the large variations in the contents of Na, K and PO4-3 in plants, calcium cannot be determined in plant-ash extracts without preliminary separation as oxalate. This applies also to abnormal sera, although there the variations in Na and PO4-3 content are not so large. 相似文献
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Nessim Sibony 《Mathematische Annalen》1987,276(2):279-290
Sans résumé 相似文献
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In this paper we give an introduction to the notion of meromorphic transform. We describe some equidistribution problems and their solution, using the ddc-method. In particular, we give some statistical properties of the equilibrium measure for meromorphic maps on compact Kähler manifolds: K-mixing, exponential decay of correlations and central limit theorem. 相似文献
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Sans résumé
Mémoire présenté par J. L. Lions 相似文献
8.
Refaat I. Nessim 《Liquid crystals》2003,30(2):211-218
Five homologous series Ia-e, of the title compounds have been prepared and investigated for their mesophase behaviour in binary mixtures. Each series differs from the other by a substituent X, which changes between CH3O, CH3, Cl, CN, and NO2. The number of carbons in the terminal alkoxy group, within a homologous series, varies between 6, 8, 14, and 16. All possible binary combinations, made from any two components bearing an alkoxy group of the same chain length but two different substituents X, were prepared and similarly characterized for their phase behaviour. Transition temperatures of the mixtures were measured by differential scanning calorimetry and identified by polarizing optical microscopy. Phase diagrams were constructed for the various binary systems and discussed in terms of electronic effects. 相似文献
9.
Binary mixtures formed from components of the five homologous series of the 4-(4-substituted phenylazo)phenyl-4-alkoxybenzoates Ia-e were prepared and their mesophase behaviour characterized. Transition temperatures of the mixtures prepared were measured by differential scanning calorimetry and identified by polarizing optical microscopy. Each binary combination was made from components bearing a terminal alkoxy group with the same number of carbon atoms (kept constant at n = 6, 8, 10, 12, 14 or 16), while the other substituent (X) was different—CH3O, CH3, Cl, NO2, or CN. Phase diagrams were constructed for the various systems in order to investigate the effect of the terminal substituent X, as well as of the alkoxy chain length, on the phase behaviour of mixed systems. 相似文献
10.
M. Sibony 《Israel Journal of Mathematics》1970,8(2):105-126
Approximation of certain functionals which are not differentiable in the sense of Gateau by differentiable ones is utilized
for solving a large class of optimization problems. Some examples from mechanics are included. 相似文献