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81.
82.
Rita CagnoliFranco Ghelfi Ugo M PagnoniAndrew F Parsons Luisa Schenetti 《Tetrahedron》2003,59(50):9951-9960
The benzoylamino group was identified as a useful radical cyclization auxiliary that can be smoothly removed on hydro-de-halogenation of chlorinated N-substituted-pyrrolidin-2-ones with Raney-Ni. This methodology was successfully implemented in a new and appealing route to the anti-epileptic drug gabapentin. 相似文献
83.
84.
Results of an electroreflectance investigation of gallium antimonide in the 3.0–4.2 eV region are presented. The observed recurrence in this region of the spin-orbit splitting of the zone-center valence band states suggests a revised assignment for the observed recurrence in this region of the spin-orbit splitting of the zone-center valence band states suggests a revised assignment for the observed structure in terms of transitions to the second conduction band states. 相似文献
85.
J.D. Parsons 《Solid State Communications》1975,17(8):935-937
Propagating waves on the free surface of a cholesteric liquid crystal in a vertical magnetic field are considered for the case when the anisotropy of the magnetic susceptibility is negative. Surface fluctuations distort the helical structure and the dispersion relation and penetration depth are shown to depend on three possible restoring forces: the surface tension, the twist elastic forces associated with the helix, and the magnetic field. 相似文献
86.
The use of emission spatial profiles for the establishment of an internal reference point in ICP-AES
T.A. Anderson D.W. Burns M.L. Parsons 《Spectrochimica Acta Part B: Atomic Spectroscopy》1984,39(4):559-566
ICP torches are essentially unique devices. They are by necessity hand-made items. Therefore each has small variations in shape which cause individual differences in plasma configuration. As a consequence, utilization of an external reference point such as the “top of the load coil” is not adequate. It is well documented that ICP sources are complex and that different excitation mechanisms come into play in different parts of the source. This is demonstrated by the fact that generally atomic transitions have their peak intensities lower in the plasma, whereas ionic transitions peak higher in the plasma. The height-intensity relationship of both atomic and ionic species has been investigated. The use of the intersection of normalized atomic and ionic emission intensity profiles as a function of observation height has been evaluated as a possible internal reference point. This point is shown to be reproducible and easy to measure. 相似文献
87.
If G is a bipartite graph with bipartition A, B then let Gm,n(A, B) be obtained from G by replacing each vertex a of A by an independent set a1, …, am, each vertex b of B by an independent set b1,…, bn, and each edge ab of G by the complete bipartite graph with edges aibj (1 ≤ i ≤ m and 1 ≤ j ≤ n). Whenever G has certain types of spanning forests, then cellular embeddings of G in surfaces S may be lifted to embeddings of Gm,n(A, B) having faces of the same sizes as those of G in S. These results are proved by the technique of “excess-current graphs.” They include new genus embeddings for a large class of bipartite graphs. 相似文献
88.
Roger Parsons 《Journal of Electroanalytical Chemistry》1977,84(2):408-409
89.
Rate laws and kinetic parameters are reported for substitution at titanium(IV) complexes Ti(LL)2X2, where LLH=cyclopentadiene, the 4-pyrone ethylmaltol, several 4-pyridinones, and related ligands, and X=halide or alkoxide, in acetonitrile solution at 298.2 K. Reactivities are discussed in terms of the nature of the leaving group, the entering group and the non-leaving ligand LL?. Activation volumes of ?15 and ?12 cm3 mol?1 have been determined for thiocyanate attack at Ti(cp)2Cl2 and Ti(etmalt)2Cl2 respectively. Substitution mechanisms are discussed in the light of the kinetic parameters obtained. 相似文献
90.
CNDO/2 Calculations have been performed on the title compounds and on the anions derived from them. The results indicate that in the anion there is significant transannular transfer of charge to the 4-position. The amount of such transfer is effectively independent of the 4-substituent. It is concluded that the effect of the substituent upon the stability of the acid must be an important factor. 相似文献