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1,3-Cyclobutanedione derivatives from ketene The dimerisation of ketene leads mainly to the methylidene-β-lactone ‘Diketene’ 2c . It is shown, that also a small amount of the symmetrical dimer, 1,3-cyclobutadione 1c is produced, which under the reaction conditions is acetylated to 3-acetoxycyclo-butenone (5) . 相似文献
146.
Wang Jian-qi Manijeh Mohraz Edgar Heilbronner Adolf Krebs Karin Schütz Jürgen Voss Brigitte Kpke 《Helvetica chimica acta》1983,66(3):801-808
The He(Iα) photoelectron (PE.) spectra of a series of substituted 1,2-dithietes have been recorded and assigned with respect to the orbital sequence derived from an STO-3G model calculation and by correlation with the PE. spectra of related compounds. The results provide additional support for the presence of a closed, four-membered ring moiety in all the 1,2-dithietes investigated. In all cases the two highest occupied molecular orbitals are b2(π)= HOMO, a2(π), with exception of 3,4-bis(trifluoromethyl)-1,2-dithiete where the sequence b2(π), a2(π) or a2(π), b2(π) is uncertain. 相似文献
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Keith Julien Edgar Knobloch Joseph Werne 《Theoretical and Computational Fluid Dynamics》1998,11(3-4):251-261
The incompressible Navier–Stokes equation is considered in the limit of rapid rotation (small Ekman number). The analysis
is limited to horizontal scales small enough so that both horizontal and vertical velocities are comparable, but the horizontal
velocity components are still in geostrophic balance. Asymptotic analysis leads to a pair of nonlinear equations for the vertical
velocity and vertical vorticity coupled by vertical stretching. Statistically stationary states are maintained against viscous
dissipation by boundary forcing or energy injection at larger scales. For thermal forcing direct numerical simulation of the
reduced equations reveals the presence of intense vortical structures spanning the layer depth, in excellent agreement with
simulations of the Boussinesq equations for rotating convection by Julien et al. (1996).
Received 30 May 1997 and accepted 4 January 1998 相似文献
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Edgar Berz 《manuscripta mathematica》1970,2(3):285-299
Let X be a compact Hausdorff space, C(X) the class of all continuous functions f: XR, considered as an ordered vector space over R with respect to its canonical order; furthermore let F be an order complete ordered vector space over R. A linear operator A: C(X)F is called bounded, if it transforms each bounded set of C(X) into a bounded set of F.The purpose of this paper is to represent such a bounded linear operator A: C(X)F as an integral Af= d with respect to some content , defined on the algebraa(X) which is generated by the open sets UX.This representation is unique, if is required to be regular (p. 11). 相似文献