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21.
n.O.e. difference spectra reveal that the preferred solution conformation of methyl enol ethers has the methyl group -periplanar to the double bond; n.O.e kinetics in a methoxy—heptatriene demonstrate the presence of both possible periplanar conformations, the energy difference being 1 kcal/mole. 相似文献
22.
I. D. Troshkina Khaing Zo Naing O. N. Ushanova Vei P’o A. A. Abdusalomov 《Russian Journal of Applied Chemistry》2006,79(9):1419-1422
Equilibrium and kinetic characteristics of rhenium sorption from sulfuric acid solutions (pH 2) by activated coals produced from coal raw materials (China) were studied. Constants of the Henry equation describing isotherms of rhenium sorption by activated coals were calculated. The effective diffusion coefficients of rhenium in the coals were determined. The dynamic characteristics of rhenium sorption and desorption were determined for the activated coal with the best capacity and kinetic characteristics. 相似文献
23.
A host-guest optical sensor for the determination of aliphatic amines as exemplified by octylamine is proposed. It is based
on the reversible fluorescence enhancement of heptakis(2,6-di-O-isobutyl)-β-cyclodextrin(DOB-β-CD) hosting tetraphenylporphyrin
(TPP) immobilized in poly(vinyl chloride) (PVC) membrane by aliphatic amine extracted from aqueous phase into membrane phase.
The optimum membrane contained 1.15 wt % TPP, 6.15 wt % DOB-β-CD as sensing reagent and other membrane materials. The fluorescence
enhancement of the membrane resulted from the formation of a stable three-component complex among DOB-β-CD, TPP, and aliphatic
amines. With the optimum conditions described, the fluorescence response of the sensor to octylamine shows a good correlation
with the theoretically derived equation in the range 1.0 × 10–6 to 8.0 × 10–4 mol/L. The response characteristics including reversibility, response time, reproducibility and lifetime and selectivity
of this optical device are also discussed in detail. This sensor has also been applied for the determination of octylamine
in water samples containing interferents with satisfactory recovery.
Received: 21 November 1999 / Revised: 10 January 2000 / Accepted: 15 January 2000 相似文献
24.
V. I. Kristya Ye Naing Tun 《Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques》2013,7(2):295-298
The distribution of the sputtering yield averaged over the ion energy and flux density of sputtered atoms in a glow discharge plasma on a surface with a small-amplitude periodic relief has been calculated. The average sputtering yield of the target has a minimum at tops of the relief due to the energy separation of ions within the near-electrode discharge layer, while the flux density of sputtered atoms in this case is maximized due to the higher density of the ion flux on these areas. 相似文献
25.
U Myint J. Tölgyessy Naing Win Khaing San Ba Han Khin Mg Myoe 《Journal of Radioanalytical and Nuclear Chemistry》1994,187(5):345-349
Radiometric Flow Injection Analysis of a radioactive (131I) sample is described. For analysis an ASIA (Ismatec) analyzer with a NaI (Tl) scintillation detector was used. 相似文献
26.
V. A. Alekseev A. V. Bagulya A. E. Volkov A. A. Gippius L. A. Goncharova S. A. Gorbunov G. V. Kalinina N. S. Konovalova N. M. Okat’eva T. A. Pavlova N. G. Polukhina N. I. Starkov Tang Naing Soe M. M. Chernyavsky T. V. Shchedrina 《Bulletin of the Lebedev Physics Institute》2017,44(11):336-339
The method of using natural track detectors, i.e., meteorite olivine crystals, is developed and improved applied to the problem of searching for superheavy nuclei in nature, in galactic cosmic rays (GCR). The new technique implements the sequence of etching, grinding, and track identification operations using the automated PAVICOM facility. The data on the track length and etching rate in combination with the results of calibration on heavy nucleus accelerators allowed the development of a technique for determining the GCR nucleus charge with an accuracy of ±2. On this basis, a significant set of experimental data on superheavy nuclei of natural origin was obtained (21743GCRheavy nucleiwithZ >20, including three nucleiwith a charge of 119?6+10). The minimum lifetime Tmin of the last-mentioned is within 50 years< Tmin < 100 years, which exceeds the lifetime of transfermium nuclei synthesized on accelerators by many orders of magnitude. The long-lived superheavy nuclei detected in the GCR spectrum can belong to the “stability island”. 相似文献
27.
Aluminium, silicon, copper, iron, magnesium and sulfur in Kalewa (Myanmar) coal were determined by fast neutron activation analysis. For activation a KAMAN A-710 Neutron Generator was used. Kalewa coal was found to be low in sulfur and relatively rich in iron. 相似文献