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51.
C.J. Hamer 《Nuclear Physics B》1982,195(3):503-521
Finite-lattice methods are used to calculate the masses of the lowest-lying baryon and meson states in the two-dimensional SU(2) Yang-Mills theory. No sign of a phase transition is seen at non-zero quark mass m. Both the meson and baryon mass vanish at m = 0: this is presumably a “chiral protection” mechanism. 相似文献
52.
Ahmed SN Anthony AE Beier EW Bellerive A Biller SD Boger J Boulay MG Bowler MG Bowles TJ Brice SJ Bullard TV Chan YD Chen M Chen X Cleveland BT Cox GA Dai X Dalnoki-Veress F Doe PJ Dosanjh RS Doucas G Dragowsky MR Duba CA Duncan FA Dunford M Dunmore JA Earle ED Elliott SR Evans HC Ewan GT Farine J Fergani H Fleurot F Formaggio JA Fowler MM Frame K Frati W Fulsom BG Gagnon N Graham K Grant DR Hahn RL Hall JC Hallin AL Hallman ED Hamer AS Handler WB Hargrove CK Harvey PJ Hazama R Heeger KM 《Physical review letters》2004,92(10):102004
Data from the Sudbury Neutrino Observatory have been used to constrain the lifetime for nucleon decay to "invisible" modes, such as n-->3nu. The analysis was based on a search for gamma rays from the deexcitation of the residual nucleus that would result from the disappearance of either a proton or neutron from 16O. A limit of tau(inv)>2 x 10(29) yr is obtained at 90% confidence for either neutron- or proton-decay modes. This is about an order of magnitude more stringent than previous constraints on invisible proton-decay modes and 400 times more stringent than similar neutron modes. 相似文献
53.
R. T. Sheen H. L. Kahler E. M. Ross P. Hamer H. F. Kuisel A. E. Childs W. C. Ball W. R. G. Atkins A. Hemmeler H. Pilwat F. Folpmers und Y. Kauko 《Fresenius' Journal of Analytical Chemistry》1936,105(3-4):151-155
Ohne Zusammenfassung 相似文献
54.
T. Tomiyama H. Suetomi W. Skorecki A. J. J. van de Velde J. Grant K. W. Brown P. A. Villaruz E. L. Breazeale R. A. Greene P. Hamer H. E. Evans L. Blanquet P. P. Tully N. M. Carter L. A. Kulski G. M. Mitilino M. P. Babkin J. C. Harral T v. Fellenberg W. Ohle R. E. Larson V. Beneš E. Nolte H. J. Bandt G. Gad D. M. Taylor L. Urbányi Käte Naumann 《Analytical and bioanalytical chemistry》1939,118(1-2):41-48
55.
A puzzling inversion of enantioselectivity dependent on catalyst loading was observed during the quinine-mediated desymmetrization of glutaric meso-anhydrides. This study presents the improvement of the catalytic path by the inclusion of carboxylic acid additives up to synthetically useful levels. The novel protocol utilizing 0.1 equiv of alkaloid and xanthene-9-carboxylic acid at room temperature (rt) was found comparable to the protocol requiring 1.1 equiv of alkaloid at ?30 °C. Thus, by altering the protocol the same catalyst produces the opposite enantiomer.This occurrence was rationalized by an extensive computational study of the interactions governing the molecular complexes formed by quinine, methanol, 3-methylglutaric anhydride, and the acetic acid. It was found that in a quinine catalyzed reaction the alcohol and the anhydride were directly hydrogen bonded to the catalyst. On the other hand, in the reaction with additive the acid intercalates between the alcohol and quinine. Due to this insertion the alcohol approaches the anhydride from the opposite face, in agreement with the observed inversion of enantioselectivity 相似文献
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