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991.
V. Lange M. A. Khan U. Eichmann W. Sandner 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1991,18(4):319-324
We report on the spectroscopy of highly excited strontium ions after resonant multistep laser excitation. The states observed belonged to then s (26≦n≦79),n d (25≦n≦83),n f (28≦n≦86) andn g (30≦n≦81) series of Sr+. A least squares fit has been applied to determine the quantum defects and their linear energy dependence in each series, together with the ionisation limit of Sr+. The analysis of our data lead to a revised value for this ionisation limit of 88 965.18±0.02 cm?1, with respect to the ground state of the Sr+ ion. Analysis of the non core-penetratingn g states yielded experimental values for the dipole and quadrupole polarizability of Sr++, which are in satisfactory agreement with previous calculations. 相似文献
992.
Atul N. Jadhav Chidananda Swamy Rumalla Bharathi Avula Ikhlas A. Khan 《Chromatographia》2007,66(9-10):797-800
Naturally occurring 20-hydroxyecdysone is an important anabolic ecdysteroid. A simple thin-layer chromatography method to quantitate 20-hydroxyecdysone in methanolic extract of the whole plant material of Sida rhombifolia L. was developed. This method was successfully applied for quantitative evaluation of dietary supplements. The separation was achieved on glass TLC plates coated with silica gel 60F254, using chloroform: methanol (8:2 v/v) as developing solvent. Densitometric evaluation of 20-hydroxyecdysone was performed at 250 nm in reflectance/absorbance mode. The calibration was in the range of 200–1,000 ng spot?1 and correlation coefficient for the calibration curve was >0.999. In addition, for six different Sida species unique fingerprints were obtained on the HPTLC plate. 相似文献
993.
M. M. Taqui Khan Debabrata Chatterjee H. C. Bajaj 《Reaction Kinetics and Catalysis Letters》1993,49(1):81-85
Selective oxidation of cyclohexane to cyclohexanone was carried out in a RuCl3-pyridine-acetic acid-KHSO5 mixture. This system yields 2.8% of cyclohexanone (based on oxone concentration) under the conditions employed. Mechanistic postulate for the oxidation reaction involves the formation of a carbene intermediate (Ru=C) prior to the ketone formation. 相似文献
994.
995.
The disappearance of collective flow effects in heavy ion collisions is investigated using a microscopic optical model formalism for estimating collision momentum transfers. Phenomenological expressions for the balance energy are obtained which agree very well with measurements for various experimental collision pairs and with results obtained from Boltzmann-Uehling-Uhlenbeck simulations. 相似文献
996.
997.
The synthesis and structures and thermal properties of two compounds: {(H2O)2K--(H2O)3-Co(H2O)3}2[V10O28] (1) and {(H2O)2K--(H2O)3-Ni(H2O)3}2[V10O28] (2) are described. These compounds have been prepared by the reaction of aqueous solutions (pH=3.5) of KVO3with MCl2·6H2O (M=Co, Ni) at 70–72°C. The isomorphous structures of the two compounds consist of interlinked chains composed of arrays of {V10O28} clusters which are joined through {(H2O)2K--(H2O)3-M(H2O)3} bridges. Thermogravimetric studies revealed the complete removal of all water molecules in multiple steps in the temperature range 90–208°C. 相似文献
998.
N. G. Zaitseva C. Deptula Kim Sen Khan O. Knotek P. Mikeć V. A. Khalkin 《Journal of Radioanalytical and Nuclear Chemistry》1988,121(2):307-321
Absorption of carrier-free T1 from nitric acid solutions of lead by ammonium 12-molybdophosphate fixed in the matrix of porous Teflon (AMP-sorbent) has been investigated. Effective separation of T1 and Pb is shown to take place. Elution processes of T1 from AMP-sorbent have been investigated. It is found that complete extraction of T1 is achieved upon dissolving AMP in concentrated ammonia. Further purification and concentration of T1 are performed by means of cation exchange chromatography on Dowex-50 or KU-2 resins. Investigation of high temperature behaviour of T1 ultramicroamounts in Pb melt showed that T1 is quantitatively separated out into the gas phase when fluorinating additions of PbF2 or NaF solid salts covering the melt surface are used. The volatile compounds of radiothallium formed were transported by a stream of inert gas (He or N2) from the evaporation zone to the thermochromatographic column, where they were sorbed on the surface in a limited zone with the maximum at 240 °C. Liquid and gas thermochromatographic methods for separation of carrier free radiothallium from protonirradiated lead material have been developed. The radiochemical, chemical and radionuclidic purity of T1 samples complies with requirements of nuclear medicine for201T1 product. Both methods ensure 95% chemical yield of T1 and take about two hours each. 相似文献
999.
M. Ali A. H. Khan A. K. M. Wahiduzzaman M. A. Malek 《Journal of Radioanalytical and Nuclear Chemistry》1997,219(1):81-87
The trace element concentrations of eight elements (Ca, Cr, Mn, Fe, Ni, Cu, Zn and Pb) in the scalp hair of 49 normal and 55 malnourished children of the Bangladesh population, in the age group of 1 to 5 years were analyzed by the external beam PIXE method to establish their baseline values in normal children for pre-diagnostic screening of deficiency and excess in malnutrition. The results of this investigation show that the ranges of trace elements in hair are somewhat wide. For example, the normal Zn level has the range of 63–377 g·g–1 for 49 subjects. The reasons for these large individual deviations are unknown till now. The average of the elemental concentrations between normal and malnourished groups are compared (t-test,p<0.05). A correlation study has been done on each pair of original data by a non-parametric Speaman's rank test. The frequency distributions of the elements are presented and the results are compared with the data reported in the literature. A substantive correspondence between the present data in hair of both the study groups and the literature values from different countries have been observed but they did not show any regular dependence on the nutritional status of the subjects. Only the low Cu content in the hair of malnourished group can possibly be linked with nutritional disorders as evidenced from this study.Part of a Ph.D. Thesis. 相似文献
1000.