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441.
442.
F. Hengl M. Harris A. Travers C. M. Smith E. H. Hamilton J. J. T. Graham A. F. Swain D. Green L. L. English L. H. Dawsey A. J. Haas H. Knight H. Martin R. S. Woglum E. R. de Ong G. P. Gray L. N. Staniland F. Tutin C. L. Walton und J. Houben 《Fresenius' Journal of Analytical Chemistry》1935,101(3-4):137-143
Ohne Zusammenfassung 相似文献
443.
C S Dyer P R Truscott C L Peerless C J Watson H E Evans P Knight M Cosby C Underwood T Cousins R Noulty C Maag 《Radiation measurements》1999,30(5):569-578
Flight data obtained between 1990 and 1997 from the Cosmic Radiation Environment Monitors CREAM & CREDO carried on UoSAT-3, Space Shuttle, STRV-1a (Space Technology Research Vehicle) and APEX (Advanced Photovoltaic and Electronics Experiment Spacecraft) provide coverage over half a solar cycle. The modulation of cosmic rays and evolution of the South Atlantic Anomaly are observed, the former comprising a factor of three increase at high latitudes and the latter a general increase accompanied by a north-westward drift. Comparison of particle fluxes and linear energy transfer (LET) spectra is made with improved environment & radiation transport calculations which account for shield distributions and secondary particles. While there is an encouraging convergence between predictions and observations, significant improvements are still required, particularly in the treatment of locally produced secondary particles. Solar-particle events during this time period have LET spectra significantly below the October 1989 event which has been proposed as a worst case model. 相似文献
444.
445.
Conformational Dependence of Through‐Space Tellurium–Tellurium Spin–Spin Coupling in Peri‐Substituted Bis(Tellurides)
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Dr. Fergus R. Knight Dr. Louise M. Diamond Dr. Kasun S. Athukorala Arachchige Paula Sanz Camacho Rebecca A. M. Randall Prof. Sharon E. Ashbrook Prof. Michael Bühl Prof. Alexandra M. Z. Slawin Prof. J. Derek Woollins 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(9):3613-3627
Three related series of peri‐substituted bis(tellurides) bearing naphthalene, acenaphthene and acenaphthylene backbones (Nap/Acenap/Aceyl(TeY)2 (Nap=naphthalene‐1,8‐diyl N ; Acenap=acenaphthene‐5,6‐diyl A ; Aceyl=acenaphthylene‐5,6‐diyl Ay ; Y=Ph 1 ; Fp 2 ; Tol 3 ; An‐p 4 ; An‐o 5 ; Tp 6 ; Mes 7 ; Tip 8 ) have been synthesised and their solid‐state structures determined by X‐ray crystallography. Molecular conformations were classified as a function of the two C9‐C‐Te‐C(Y) dihedral angles (θ); in the solid all members adopt AB or CCt configurations, with larger Te(aryl) moieties exclusively imposing the CCt variant. Exceptionally large J(125Te,125Te) spin–spin coupling constants between 3289–3848 Hz were obtained for compounds substituted by bulky Te(aryl) groups, implying these species are locked in a CCt‐type conformation. In contrast, compounds incorporating smaller Te(aryl) moieties are predicted to be rather dynamic in solution and afford much smaller J values (2050–2676 Hz), characteristic of greater populations of AB conformers with lower couplings. This conformational dependence of through‐space coupling is supported by DFT calculations. 相似文献
446.
447.
Cover Picture: Selective Oxidation of Alkyl‐Substituted Polyaromatics Using Ruthenium‐Ion‐Catalyzed Oxidation (Chem. Eur. J. 11/2015)
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448.
Selective Oxidation of Alkyl‐Substituted Polyaromatics Using Ruthenium‐Ion‐Catalyzed Oxidation
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Ewa Nowicka Meenakshisundaram Sankar Robert L. Jenkins David W. Knight David J. Willock Graham J. Hutchings Manuel Francisco Stuart H. Taylor 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(11):4285-4293
Ruthenium‐ion‐catalyzed oxidation of a range of alkylated polyaromatics has been studied. 2‐Ethylnaphthalene was used as a model substrate, and oxidation can be performed in either a conventional biphasic or in a monophasic solvent system. In either case the reaction rates and product selectivity are identical. The reaction products indicate that the aromatic ring system is oxidized in preference to the alkyl chain. This analysis is possible due to the development of a quantitative NMR protocol to determine the relative amounts of aliphatic and aromatic protons. From a systematic set of substrates we show that as the length of the alkyl chain substituent on a polyaromatic increases, the proportion of products in which the chain remains attached to the aromatic system increases. Larger polyaromatic systems, based on pyrene and phenanthrene, show greater reactivity than those with fewer aromatic rings, and the alkyl chains are more stable to oxidation. 相似文献
449.
Amany M. Ghanim David W. Knight Piotr M. Rutkowski Nermine A. Osman Hanan A. Abdel-Fattah Azza M. Kadry 《Tetrahedron letters》2017,58(4):294-297
Carbenium ions generated from substituted benzhydryls using acid catalysis undergo smooth intramolecular trapping by pendant sulfonamide groups to provide excellent yields of 1-aryltetrahydroisoquinolines. 相似文献
450.
Yulia Ryabenkova Peter J. MiedziakDavid W. Knight Stuart H. TaylorGraham J. Hutchings 《Tetrahedron》2014
The oxidation of four butanediols under base-free conditions has been investigated using a set of Au, Pd and Pt catalysts prepared using sol-immobilization. The supported nanoparticles are found to be active with bimetallic alloys having much higher activity when compared with the monometallic counterparts. In general the AuPt catalysts are the most active and in all cases the corresponding C4 oxidation products were observed with high selectivity; sequential reaction of these products leads to the formation of acetic acid as an undesired by-product. 相似文献