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81.
Enrico Mincione Anthony J. Pearson Paolo Bovicelli Malcolm Chandler Geoffrey C. Heywood 《Tetrahedron letters》1981,22(30):2929-2932
New Methodology is described for the synthesis 6-ketosteroids, of potential value for the synthesis of β-ecdysone, tricarbonyl (4-methoxy-1-methylcyclohexadienyl) iron hexafluorophosphate . 相似文献
82.
A range of fluorohalogenated methyl propyl ethers has been prepared for screening as potential inhalation anaesthetics. Many compounds tested were either convulsant or caused marked respiratory depression. Only 2,2,3,3-tetrafluoropropyl methyl ether showed good anaesthesia without side effects, but would also be expected to be flammable at clinical concentrations. 相似文献
83.
A range of fluorinated methyl ethyl ethers, diethyl ethers and methyl butyl ethers has been synthesised as potential inhalation anaesthetics. Seven compounds produced anaesthesia with minimal side effects in mice, and their biological testing will be reported in more detail elsewhere [1]. 相似文献
84.
85.
Reaction of cyclohexadienylium-Fe(CO)3 complexes (7) and (8) with sodiomalono-nitrile gives the carbo-spirocyclic derivatives (9) and (10), whilst reaction with benzylamine and removal of iron leads to the azaspirocyclic enones (15) and (16), respectively. 相似文献
86.
87.
Complex moduli are calculated for the lowest-order deviations from linearity of the stress in an oscillatory shear field. The calculations involve solution of an equation, recently proposed by Doi, which goes beyond the “independent alignment approximation” of the Doi-Edwards theory of polymer dynamics. The new equation incorporates various reptative motions of a polymer in the effective constraining tube induced by entanglements, viz. Brownian motion along the tube and the systematic motion in response to changes in the length of the tube accompanying affine deformation. 相似文献
88.
We consider the thermally driven motion of a microcantilever in a fluid environment near a wall, a configuration characteristic of the atomic force microscope. A theoretical model is presented which accounts for hydrodynamic interactions between the cantilever and wall over a wide range of frequencies and which exploits the fluctuation-dissipation theorem to capture the Brownian dynamics of the coupled fluid-cantilever system. Model predictions are tested against experimental thermal spectra for a cantilever in air and water. The model shows how, in a liquid environment, the effects of non-delta-correlated Brownian forcing appear in the power spectrum, particularly at low frequencies. The model also predicts accurately changes in the spectrum in liquid arising through hydrodynamic wall effects, which we show are strongly mediated by the angle at which the cantilever is tilted relative to the wall. 相似文献
89.
Denzer W Horrocks SJ Pearson PJ Ritchie GA 《Physical chemistry chemical physics : PCCP》2006,8(16):1954-1962
The translational anisotropy and the polarization of the electronic angular momentum of the O ((1)D2) fragment produced from the 298 nm photodissociation of ozone have been determined using resonance enhanced multiphoton ionization (REMPI) in conjunction with time-of-flight mass spectrometry (TOFMS). The translational anisotropy parameter beta, which is necessarily averaged over the O2 co-fragment rotational distribution, is measured to be 1.08 +/- 0.04. This is consistent with that expected for the (1)B2 <-- (1)A1 transition within an impulsive model if the tangential velocity associated with the zero point motion of the bend is constricted to opening the bond angle. Molecular frame polarization parameters of rank up to k = 4 have been extracted for the O ((1)D2) fragment and the calculated m(J) populations show a strong preference for the absolute value(m(J)) = 1 states. A small coherence term is also observed, a manifestation of the nuclear geometry of the dissociating molecule and the existence of possible non-adiabatic processes in the exit channel. The orientation associated with the mapping of the photon helicity onto the O ((1)D2) electronic angular momentum distribution was observed to have been quenched. However, the parameter gamma1', which describes the contribution to the orientation from a coherent superposition of a parallel and perpendicular excitation where the photofragment angular momentum lies perpendicular to both the recoil velocity and to the transition dipole moment, was determined to be -0.06. 相似文献
90.
Hyland B Svensson CE Ball GC Leslie JR Achtzehn T Albers D Andreoiu C Bricault P Churchman R Cross D Dombsky M Finlay P Garrett PE Geppert C Grinyer GF Hackman G Hanemaayer V Lassen J Lavoie JP Melconian D Morton AC Pearson CJ Pearson MR Phillips AA Schumaker MA Smith MB Towner IS Valiente-Dobón JJ Wendt K Zganjar EF 《Physical review letters》2006,97(10):102501
A high-precision branching ratio measurement for the superallowed beta+ decay of 62Ga was performed at the Isotope Separator and Accelerator radioactive ion beam facility. Nineteen gamma rays emitted following beta+ decay of 62Ga were identified, establishing the dominant superallowed branching ratio to be (99.861+/-0.011)%. Combined with recent half-life and Q-value measurements, this branching ratio yields a superallowed ft value of 3075.6+/-1.4 s for 62Ga decay. These results demonstrate the feasibility of high-precision superallowed branching ratio measurements in the A>or=62 mass region and provide the first stringent tests of the large isospin-symmetry-breaking effects predicted for these decays. 相似文献