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101.
Fire-asay preconcentration followed by neutron-activation analysis permits the determination of as little as 0.5 ppM of platinum and 0.5 ppM of palladium on a 20-g sample. Platinum and palladium are separated with carriers and beta-counted. Results for the platinum and palladium content of seven U.S.G.S. standard rocks are presented. 相似文献
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C.J. Glinka J.M. Rowe J.J. Rush G.G. Libowitz A. Maeland 《Solid State Communications》1977,22(9):541-544
The complete phonon dispersion relation including both optic and acoustic modes has been measured along the major symmetry axes of a single crystal of CeD2.12 at 295 K by coherent neutron scattering. The results show the inadequacy of simple models previously used for the analysis of neutron incoherent scattering studies of rare earth dihydrides. The interstitial mode of vibration due to the excess deuterium (above CeD2 in octahedral sites has also been observed. 相似文献
107.
The proton magnetic resonance spectra of a number of annelated biphenylenes are given. The influences of ring currents and bond-localisation effects are demonstrated. 相似文献
108.
The use of molecular modelling in the interpretation of inverse gas chromatography data is discussed. Crystal faces can be visualised and likely cleavage planes calculated using the surface attachment energies. Assuming that the preferred cleavage plane is the crystal face with the smallest attachment energy then the predominant crystal faces of a crystalline particle can be predicted. Surface adsorption can be modelled using Van der Waals and electrostatic interactions to evaluate the interaction energies between individual atoms of the probe molecule and atoms of the test molecule orientated as in the surface. Using examples of pharmaceutical materials, modelling has been shown to be successful in the understanding of changes in the surface energetics. 相似文献
109.
2-Methyl- and 2,4-dimethylbenzophenone were irradiated with the unsymetrical dienophiles methyl acrylate, acrylonitrile, methyl methacrylate and methyl propiolate. The dienols additions proceed regiospecifically yielding in each instance a single hydroxylic compound having the car?ylate or the carbonitrile group in vicinal position. Syntheses of 1,2,3,4-tetrahydro- and 1,4-dihydronaphthols with various substituents were thus achieved. 3,4-Dihydronaphthalenes and naphthalenes were also obtained by dehydration. 2,4-dimethylbenzophenone was irradiated with acetylenedicarbonitrile yielding the dehydrated addition product 6-methyl 1-phenylnaphthalene-2,3-dicarbonitrile. 相似文献
110.
Clark SB O'Rangers JJ Rowe WD Madson MR Hurlbut JA Sofos JN Fuerst B James G Griffith S Readnour RS 《Journal of AOAC International》2002,85(6):1260-1267
The objective of this study was to compare 2 methods for the determination of tilmicosin residues in bovine liver samples. Three laboratories participated in the comparison of the 2 methods. The first method was described in a New Animal Drug Application (NADA 140-929), and the second was a modification of that method in which hexane was substituted for carbon tetrachloride in one cleanup step. Each of the 3 laboratories analyzed subsamples of 10 bovine livers containing incurred tilmicosin. Residues ranged from 2.3 to 81 ppm tilmicosin in the 10 liver samples with an 11.8% relative standard deviation obtained by using both methods. In addition, fortified-control liver tissue samples were analyzed concurrently with tissues containing incurred residues by using the modified method in one of the laboratories. The fortification levels ranged from 0.3 to 112 ppm, with recoveries ranging from 76 to 92%. The results from the 3 laboratories were comparable, indicating that the modified method was not only as effective as the original NADA method, but also more desirable because of the change to a less hazardous solvent. 相似文献