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71.
Georg Pick 《Mathematische Annalen》1893,42(4):489-496
Ohne Zusammenfassung 相似文献
72.
Transport of two principal inorganic iodine anions separately in two crushed crystalline granitic rocks, gabbro and tonalite, have been investigated. The rocks were crushed and sieved, and finally a fraction between 0.25 and 0.80 mm was filled in 5 cm3 PET columns (medical syringes) of 5.40 cm length and 1.24 cm in inner diameter. NaI and NaIO3 were dissolved in synthetic groundwater (SGW) in a concentration as low as 10?4 mol/dm3. The SGW was pumped into the columns at a seepage velocity of 0.031 ± 0.001 cm/min using a multi-head peristaltic pump. Iodine concentration in the outflow SGW from the columns was determined by UV–Vis spectrophotometry at 510 nm absorption maximum in CHCl3 using redox reactions. By the use of a dependence of concentration on the number of pore volumes from the outflow and the linear isotherm model, based on erfc-function, breakthrough curves were constructed and the principal transport parameters were calculated. The values of sorption and desorption retardation coefficients of about 1 for both iodide and iodate have been obtained, which show evidence of practically non-sorption behavior of these chemical forms of iodine in the tested granitic rocks. The values of hydrodynamic dispersion coefficients and corresponding Peclet numbers were about 0.0077 ± 0.0006 and 21.6 ± 1.8 cm2/min, respectively, for both anions and rocks under given conditions. 相似文献
73.
Transport of 125I?, 137Cs+ and 85Sr2+ radionuclides in crushed granitoidic rocks and homogenized soils was studied. Two simple methods for calculation of breakthrough curves in flow column experiments with groundwater as transport medium have been described. The first method, so called non-linear approach, is derived on the assumption of a reversible non-linear sorption isotherm described with Freundlich equation, i.e., with non-constant distribution and retardation coefficients. The second method, so-called linear approach, is applied for reference only, and is based on the assumption of a reversible sorption characterized with linear sorption isotherm, i.e., with constant distribution and retardation coefficients. Both methods model the experimental breakthrough curves with the integrated form of the simple 1-D advection–dispersion equation (ADE) expressed analytically for pulse application of radiotracer to the liquid phase before entering the columns. The integrated form of the ADE equation was modified by the so-called peak position and peak height correction coefficients the advantage of which consists among others in the elimination of the influence of starting concentration. The comparison of both approaches has shown that fitting by means of non-linear approach has given rather reliable values of the transport parameters and calculated dependences, especially in a case of 137Cs system characterized evidently with non-linear type of sorption isotherms. As for 125I?, the sorption capacity of all solid samples studied is nearly on the zero level and 125I? is practically not retarded, and from this point of view it behaves as non-interacting component. In addition, it was found that the modified ADE gives rather better results than the classical one. 相似文献
74.
Ohne Zusammenfassung 相似文献
75.
76.
Summary Since its introduction around 1977, OPLC has found widespread application and its methodology has been further developed.
A possible development is gradient elution. Different continuous development methods (e.g. with eluent changeover, multistep
gradient) and the possible system configurations for their execution are discussed. The advantages of the newly developed
continuous development techniques are compared to earlier data. The most versatile method is demonstrated on lipid samples
derived from human plasma, giving separation of six lipid classes and intra-class separation of the most polar classes in
the same run. 相似文献
77.
Š. Palágyi 《Journal of Radioanalytical and Nuclear Chemistry》1988,121(2):323-330
A study is presented on the use of isotopic and non-isotopic ion exchange in a heterogeneous liquid-liquid system for the separation of131I from water. The method is based on the reaction between radioiodide in the aqueous phase and trioctylmethylammonium iodide or chloride in the organic phase. The effect of some important experimental parameters on the separation efficiency is discussed. It has been found that under optimum conditions the method of isotopic ion exchange can be used for the radiochemical determination of iodine in water. 相似文献
78.
Š. Beňačka L'. Bezáková Š. Gaži S. Takács J. Palaj 《Czechoslovak Journal of Physics》1978,28(2):192-202
We have studied the properties of long (lengthL20m) superconducting threads (Pb of Sn) formed by pulse electrical breakdown in monocrystalline silicon. These variable thickness bridges have well defined dc and ac Josephson effects in wide temperature range. Some interesting results on the quasiparticle subharmonic gap structures are also reported.The authors would like to express their thanks to J.Móza and A.Neasová for technical assistance. 相似文献
79.
Zusammenfassung Die vonBarker und Mitarbeitern angegebene Methode der Blutjodbestimmung ist sehr einfach und genau. Sie wird auch zur Bestimmung des Jods in Milch empfohlen.
Summary The blood iodine determination devised byBarker and associates is very simple and accurate. It is likewise recommended for the determination of iodine in milk.
Résumé La méthode décrite parBarker et collaborateurs pour le dosage de l'iode dans le sang est simple et précise. Elle est également recommandée pour le dosage de l'iode dans le lait.相似文献
80.
J. Masár Ľ. Kuchta H. Gerthofferová V. Š. Fajnor 《Journal of Thermal Analysis and Calorimetry》1982,24(1):43-50
The thermal behaviour of synthetic montmorillonite of relatively simple chemical composition has been studied and interpreted. Montmorillonite was prepared by hydrothermal synthesis at 300° and 8.8 MPa during 165 hours. With the methods of DTA, DTG, TG, X-ray diffraction analysis, infrared spectroscopy and electron microscopy it was proved that the synthetic montmorillonite is a monomineral sample and no differences from natural montmorillonite were observed.
Zusammenfassung Das thermische Verhalten synthetischer Montmorillonite verhältnismässig einfacher chemischer Zusammensetzung wurde untersucht und gedeutet. Montmorillonit wurde durch hydrothermische Synthese bei 300°C und 8.8 MPa in 165 Stunden hergestellt. Durch die Methoden der DTA, DTG, TG, Röntgendiffraktionsanalyse, Infrarotspektroskopie und Elektronenmikroskopie wurde erwiesen, daß synthetische Montmorillonit eine monominerale Probe ist und keine Abweichungen von natürlichem Montmorillonit beobachtet werden konnten.
. 165 300° 8.8 . , , , , , .相似文献