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991.
Henrik L. Selberg 《Commentarii Mathematici Helvetici》1934,7(1):171-177
Ohne Zusammenfassung 相似文献
992.
993.
994.
During the last years both Erd?s space and complete Erd?s space were topologically characterized by Dijkstra and van Mill. Applications include results about Erd?s type spaces in ?p-spaces as well as results about Polishable ideals on ω. We present an unifying theorem in terms of sets with a reflexive relation that among other things contains these apparently dissimilar results as special cases. 相似文献
995.
Sergey Sergeyev Sara Stas Adrienne Remacle Christophe M.L. Vande Velde Bohumil Dolenský Martin Havlík Vladimír Král Jan Čejka 《Tetrahedron: Asymmetry》2009,20(16):1918-1923
The separation of enantiomers of several ‘bis- and tris-Tröger’s bases’ by HPLC on commercially available chiral stationary phase Whelk O1 is described for the first time. The observed structure–enantioselectivity relationships are in agreement with the previously established molecular recognition model. For all ‘bis- and tris-Tröger’s bases’ studied, satisfactory to excellent enantioselectivities were observed. 相似文献
996.
The electronic structure and the electron dynamics of the clean InAs(1 1 1)A 2 × 2 and the InAs(1 1 1)B 1 × 1 surfaces have been studied by laser pump-and-probe photoemission spectroscopy. Normally unpopulated electron states above the valence band maximum (VBM) are filled on the InAs(1 1 1)A surface due to the conduction band pinning above the Fermi level (EF). Accompanied by the downward band banding alignment, a charge accumulation layer is confined to the surface region creating a two dimensional electron gas (2DEG). The decay of the photoexcited carriers above the conduction band minimum (CBM) is originated by bulk states affected by the presence of the surface. No occupied states were found on the InAs(1 1 1)B 1 × 1 surface. This fact is suggested to be due to the surface stabilisation by the charge removal from the surface into the bulk. The weak photoemission intensity above the VBM on the (1 1 1)B surface is attributed to electron states trapped by surface defects. The fast decay of the photoexcited electron states on the (1 1 1)A and the (1 1 1)B surfaces was found to be τ1 1 1 A ? 5 ps and τ1 1 1 B ? 4 ps, respectively. We suggest the diffusion of the hot electrons into the bulk is the decay mechanism. 相似文献
997.
998.
Summary The composition of the eluent system in some instances determines the resolution and elution order of solutes in the reversed-phase chromatographic separation on cyclodextrin stationary phases. Both the identity and the concentration of the organic modifier can play a large role. The effect is particularly pronounced with naphthalene and its methyl derivatives with alcohol eluents.
Elutionsfolge bei der Flüssig-Chromatographie auf Cyclodextrinphasen. Abhängigkeit vom Gehalt an organischem Modifier im Eluenten相似文献
999.
Rate constants and activation parameters of direct reaction of oxirane with certain alkyl-2-hydroxyethyl sulfides and/or successive oxyethylene adducts in the presence of basic catalyst were studied at temperatures 323–353 K. The reactions were found to be of the first order with respect to oxirane, sulfide, and catalyst concentrations. The kinetics are consistent with a termolecular mechanism. 相似文献
1000.
Ohne Zusammenfassung 相似文献