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71.
Michael J. Cook Ghoabad Ghaem-Maghami Festus Kaberia Knut Bergesen 《Magnetic resonance in chemistry : MRC》1983,21(5):339-343
1H NMR Parameters are reported for five 1,4-dithiepan-6-ones. 1,4-Dithiepan-6-one 1-oxide exists in solution as an equilibrium involving two different twist-chair conformations, which contrasts with its conformational behaviour in the solid state. Twist-chair conformers are also adopted by other members of the series, the favoured form varying with ring substitution. The S?O bond in 1,4-dithiepan-6-one 1-oxide and in its 5,5-dimethyl analogue exhibit a preference for the pseudoaxial site. 相似文献
72.
Andrew V. Chapman Michael J. Cook Alan R. Katritzky Michael H. Aabraham Angela F. Danil De Namor Lilane Dumont Jacques Reisse 《Tetrahedron》1978,34(10):1571-1575
The dehydration of various 4,5-dihydro-4- and -5-hydroxy derivatives of pyrazole and isoxazole has been investigated. Heats of dehydration of 4,5-duiydro-4-hydroxy-1,3,5-tripbenylpyrazole and 4,5-dihydro-5-hydroxy-isoxazole are evaluated and used to assess the empirical resonance energy and conjugation energy of pyrazole and isoxazole. The former possesses resonance stabilisation comparable to pyrrole but that of the latter is low. 相似文献
73.
Recent proposals for using plasma wakefield accelerators (PWFA) as a component of a linear collider have included intense electron beams with densities many times in excess of the plasma density. The beam's electric fields expel the plasma electrons from the beam path to many beam radii in this regime. We analyze here the motion of plasma ions under the beam fields, and find for a proposed PWFA collider scenario that the ions completely collapse inside of the beam. Simulations of ion collapse are presented. Implications of ion motion on the feasibility of the PWFA-based colliders are discussed. 相似文献
74.
[reaction: see text] The Pd-catalyzed carbocyclization of ketoamides was investigated and found to be highly dependent on the phosphine ligand as well as the presence of coordinating counterions. Nitrogen heterocycles were formed without erosion of the stereochemical integrity. The utility of the lactam products was demonstrated by the formal synthesis of (+)-alpha-allokainic acid. 相似文献
75.
The indium-mediated allylation of chiral hydrazones was investigated. Essentially complete diastereoselectivity and quantitative yields were obtained for substrates derived from both aromatic and aliphatic aldehydes. [reaction--see text] 相似文献
76.
Superficially, the free disposal hull production possibility set (pps) can be regarded as a binary version of the Banker, Charnes and Cooper pps, in which only one component of the vector, λ, is non-zero and of necessity equal to 1. We therefore propose, by analogy with a pps due originally to Koopmans, a new pps which retains the binary characteristic of the components of λ but permits more than one component to be non-zero. Thus, a given DMU's performance is assessed not only against the individual DMUs included in the sample but also against composite DMUs obtained by simple aggregation. This approach is demonstrated and investigated on a published data set. 相似文献
77.
Abe K Abe K Abe T Adam I Akimoto H Aston D Baird KG Baltay C Band HR Barklow TL Bauer JM Bellodi G Berger R Blaylock G Bogart JR Bower GR Brau JE Breidenbach M Bugg WM Burke D Burnett TH Burrows PN Calcaterra A Cassell R Chou A Cohn HO Coller JA Convery MR Cook V Cowan RF Crawford G Damerell CJ Daoudi M de Groot N de Sangro R Dong DN Doser M Dubois R Erofeeva I Eschenburg V Fahey S Falciai D Fernandez JP Flood K Frey R Hart EL Hasuko K Hertzbach SS Huffer ME Huynh X Iwasaki M Jackson DJ 《Physical review letters》2003,90(14):141804
We present an improved direct measurement of the parity-violation parameter A(b) in the Z boson-b-quark coupling using a self-calibrating track-charge technique applied to a sample enriched in Z-->bb events via the topological reconstruction of the B hadron mass. Manipulation of the Stanford Linear Collider electron-beam polarization permits the measurement of A(b) to be made independently of other Z-pole coupling parameters. From the 1996-1998 sample of 400,000 hadronic Z decays, produced with an average beam polarization of 73.4%, we find A(b)=0.906+/-0.022(stat)+/-0.023(syst). 相似文献
78.
79.
80.
Ice nucleating-active Pseudomonas fluorescens F264C was fed to Colorado potato beetles to determine bacterial retentioin in the beetle gut and its effect on the cold hardiness of this insect pest. The bacrterium was present in beetles recovered after overwintering in the field, seven months after their exposure to P. fluorescens. Retention was evident not only in the detection of the P. fluorescens ice nucleating gene, inaW, in bacterial cultures from beetle guts but also in the elevated supercooling points of some treated beetles. 相似文献