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991.
992.
Bogdan Kuchta 《Physics letters. A》1984,103(4):202-204
The symmetry-allowed configurations of magnetic spins in the β phase of solid oxygen have been calculated in the framework of the general molecular field approximation. The three-sublattice configuration has been found to be most stable while the two-sublattice structure (the α phase) requires the elastic deformation which accompanies the α-β structural phase transition. 相似文献
993.
Bogdan Constantinescu Angela Vasilescu Martin Radtke Uwe Reinholz 《Applied Physics A: Materials Science & Processing》2010,99(2):383-389
In the determination of the provenance of gold in archaeological artifacts, trace elements are more significant than the main
components. Several minute fragments of natural Carpathian gold—placer and primary—and some very small (a few milligrams)
fragments of archaeological items were studied using micro Synchrotron Radiation X-Ray Fluorescence (micro SR-XRF) at the
BESSY Synchrotron Facility in Berlin, Germany. The goal of the study was to identify the trace elements characterizing Carpathian
gold, looking especially at Sn, Sb, Pb and Te, and to determine if the gold in the archaeological items is native or refined.
Applications to the authentication and provenance of nine Dacian gold bracelets, koson coins and two Bronze Age items are
presented. 相似文献
994.
A mathematical hydrodynamic model of a thin liquid film flowing radially on a flat horizontal surface has been elaborated. The model consisted of continuity and momentum equations which were resolved by means of the integral method. In fact, several versions of the model were examined; they differed mainly in film velocity distribution. The predictions of the different versions were then compared with liquid film thicknesses obtained from experimental investigation. The best version was applied in further calculations. 相似文献
995.
We study nonnegative harmonic functions of symmetric α-stable processes on d-sets F. We prove the Harnack inequality for such functions when α∈(0,2/dw)∪(ds,2). Furthermore, we investigate the decay rate of harmonic functions and the Carleson estimate near the boundary of a region in F. In the particular case of natural cells in the Sierpiński gasket we also prove the boundary Harnack principle. To cite this article: K. Bogdan et al., C. R. Acad. Sci. Paris, Ser. I 335 (2002) 59–63. 相似文献
996.
Lawrence R. Phillips Kathleen A. Gallo Gerald Zon Wojciech J. Stec Bogdan Uznanski 《Journal of mass spectrometry : JMS》1985,20(12):781-783
The positive and negative fast atom bombardment (FAB) mass spectra of representative dimeric O-isopropyl oligodeoxyribonucleotide triesters were recorded and examined. Features found to be shared among the FAB mass spectra of these compounds yielded important information regarding molecular weight, nucleobase composition and nucleotide sequence. 相似文献
997.
Bogdan Kuchta 《Chemical physics》1985,95(3):391-399
The lattice dynamics of the ordered phases of solid oxygen have been studied. The anharmonic shifts for the librational excitations have been calculated. The comparison of harmonic and anharmonic results has shown that anharmonic effects in, solid oxygen are very important. An analysis of the influence of the magnetic ordering in the antiferromagnetic α phase suggest that magnetic interactions and elastic deformation of the crystal unit cell can compensate each other and lead to the accidental degeneration of the As and Bs librational energies in the α phase. 相似文献
998.
Bogdan Marciniec Zenon Foltynowicz WOdzimierz Urbaniak Juliusz Perkowski 《应用有机金属化学》1987,1(3):267-273
Gas-phase hydrosilylation of acetylene by tri-chlorosilane catalyzed in a continuous flow apparatus by rhodium and ruthenium phosphine complexes immobilized on the silica via mercapto, phosphine, amine and nitrile ligands has been studied. GLC analysis of the reaction products showed vinyltrichlorosilane to be accompanied by products of double hydrosilylation of acetylene and the redistribution of trichlorosilane followed by the hydrosilylation and hydrogenative hydrosilylation of acetylene with dichlorosilane. A scheme for this complex competitive–consecutive reaction was proposed. The yield and selectivity of vinyltrichlorosilane can be much improved under special reaction conditions, e.g. rate flow of the particular substrates, temperature, given catalyst and others. Kinetic measurements carried out in the range of 115–140°C allowed us to evaluate the activation energy, Ea, for the vinyltrichlorosilane synthesis, which varied between 20.5 and 27.6 kJ mol?1 for the selected rhodium and ruthenium supported complexes. 相似文献
999.
Piotr Konieczka Thomas P. J. Linsinger Bogdan Zygmunt Jacek Namieśnik 《Accreditation and quality assurance》2005,10(5):241-251
Eighteen Polish laboratories participated in a proficiency test for the determination of PCBs in river sediment. The participants used their in-house method. The aim of the exercise was to obtain information about the state of the art of PCB analysis in environmental samples. Five PCBs (IUPAC nos. 52, 118, 138, 153 and 180) were selected for the test. The relative standard deviation of the analytical results submitted varied from 45 to 65%, with an outlier rate of 7%. The averages of the results for all analytes were in good agreement with reference values. 相似文献
1000.
Ion Grosu Luminita Muntean Loïc Toupet Gerard Plé Monica Pop Mirela Balog Sorin Mager Elena Bogdan 《Monatshefte für Chemie / Chemical Monthly》2002,133(5):631-641
Summary. The synthesis and stereochemistry of new 1,3-dioxane derivatives of 1,4-diacetylbenzene are reported. The anancomeric structure
of these compounds, the axial orientation of the aryl group for both 1,3-dioxane rings, and the cis and trans isomerism of some of these compounds is discussed considering data of conformational analysis, NMR investigations, and single
crystal X-ray diffractometry.
Received September 12, 2001. Accepted (revised) November 5, 2001 相似文献