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901.
Dalpanin, isolated from the flowers ofDalbergia paniculata (Roxb.) has been characterised as aC-glycosylisoflavanone by chemical and spectral evidence. A provisional structure (IV) is assigned to this new compound. 相似文献
902.
Muonic x-ray transitions in various spherical nuclei in the region 13?Z?83 have been analysed and the isotope and isotone shifts in charge radiusR are investigated. AssumingR=r 0 A 1/3, the isotopic and isotonic behaviour of the parameterr 0 (=RA ?1/3) is also studied. The variation ofr 0 with mass numberA reveals the variation of average nucleon density, which in turn sheds light on the compressibility of nuclear matter. The isotope and isotone shifts inR exhibit the shell effects in the vicinity of magic neutron and proton numbers: 20, 28, 50, 82 and 126. The results indicate that neutron-proton interaction is maximum at the beginning of a major neutron shell and decreases gradually as the shell gets filled up. The behaviour of parameterr 0 clearly suggests that low-Z nuclei are highly compressible while high-Z nuclei are more or less incompressible. The parameterr 0 too is observed to exhibit profound shell effects. 相似文献
903.
Two methods for symmetrizing Markov processes are discussed. Letu
a(x, y) be the potential density of a Lévy process on a compact Abelian groupG. A general condition is given that guarantees thatv(x, y)=ua(x, y)+ua(y, x) is the potential density of a symmetric Lévy process onG. The second method arises by considering the linear space of one-potentialsU
1
f, withf inL
2, endowed with the inner product (U
1
f,U
1
g)=fU
1
g+gU
1
f. If the semigroup ofX(t) is normal, then the completionH of this space is the Dirichlet space of a symmetric processY(t). A set that is semipolar forX(t) is polar forY(t). 相似文献
904.
905.
L3VV Auger transitions of copper alloys show a feature due to a band-like states, the shape and intensity of which depend on
the composition. The energy separation between this feature and the L3M4·5M4·5 peak increases progressively with Cu concentration. 相似文献
906.
The preparation and spectral properties are reported for a series of ten mixed-ligand copper(II) complexes of the form [Cu(A)(B)n](X), where A is acetylacetonate anion, B represents a mono- or bidentate ligand such as morpholine, piperidine, isonicotinic acid hydrazide, 2,2′-bipyridine, 1,10-phenanthroline and X is variously NO?3 or ClO?4 anion and n = 1 or 2. The coordination of the anions and ligands has been demonstrated by infrared and electronic spectral methods. Electron spin resonance spectral data show the square-pyramidal five-coordinated arrangement around copper(II) in these complexes. Parameters such as g6, g⊥, A6, A⊥, 〈g〉 and 〈A〉 calculated from electron spin resonance data in solid and solution state at room temperature as well as frozen solution indicate the presence of the unpaired electron in the dx2?y2 or dz2 orbital. These results are in good agreement with electronic and photoacoustic spectral studies. 相似文献
907.
908.
909.
Two non desarguesian flag transitive planes of order 34 whose Kernel is GF(3) are constructed. These planes are distinct from the planes of the same order contained in the class constructed by Narayana Rao M. L. (Proceedings of American Mathematical Society 39 (1973) 51–56) and Ebert, G.L. and Baker, R. (Enumeration of two dimensional Flag-Transitive planes, Algebras, Groups and Geometries 3 (1985) 248–257). The Flag Transitive group modulo the scalar collineations of these planes is generated by two elements and is of order 328. 相似文献
910.
N. Bharateswara Rao M. Rangacharyulu P. Venkatacharyulu D. Premaswarup 《Magnetic resonance in chemistry : MRC》1984,22(1):1-5
A temperature variation study of the nuclear quadrupole resonance (NQR) frequencies for the two resonance lines in 1,2,4,5-tetrabromobenzene was carried out in the range 77–300 K. The far-infrared spectrum of 1,2,4,5-tetrabromobenzene was recorded and the low-frequency vibrational modes noted. From the nine observed frequencies, the torsional modes contributing to the change in NQR frequencies with temperature are identified by correlating the calculated values of the NQR frequencies at different temperatures with the observed values. 相似文献