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1.
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An efficient, regio- and stereoselective palladium-catalyzed route to tetrasubstituted olefins has been developed, which involves the intermolecular coupling of an aryl iodide, an internal alkyne, and an arylboronic acid. The reaction involves cis-addition of the aryl group from the aryl halide to the less hindered or less electron-poor end of the alkyne, while the aryl group from the arylboronic acid adds to the other end. [reaction: see text] 相似文献
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R. J. Emrich 《Shock Waves》1996,5(6):327-339
Recollections of activities in the Physics Department of Princeton University leading to the construction and use of the SHOCK
TUBE are recorded. Walker Bleakney was the leader of these activities from 1940 to 1979, and his methods and attitude are
described. Original interferograms made at Princeton show some results obtained. 相似文献
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We demonstrate the connection between matrix elements of one body operators in odd nuclei and vertex functions. The procedure is free of assumptions on the pole distribution of the two point functions and it does not use perturbation theory. The renormalization of the external field, necessistated by configuration space limitations, is carried through for scalar, local fields, acting on the density and for radiation fields of the electric multipole type using the requirement of gauge invariance. It is shown that this renormalization is possible, even if the renormalized field is strongly energy dependent due to configuration mixing. 相似文献
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Liondas CA; Chrissoulidis DP 《The Quarterly Journal of Mechanics and Applied Mathematics》2007,60(3):275-287
This paper is intended to clarify a misunderstanding concerningthe source singularity of the electric Green's tensor for aperfectly conducting semi-infinite cone of circular cross-section.Tai's series expansion of the Green's tensor is known to lacka singular term at the source region. Jones has reconstructedthe solution to this problem and has pointed out the differencebetween his result and that of Tai. The aim of our paper isto demonstrate that, although Jones's closed-form solution iscorrect, there is a mistake in his comparison with Tai's seriessolution. We conclude that one of the two additional singularterms that Jones claims as missing from Tai's formula must beomitted. Besides, we compare Jones's closed-form solution withSmyshlyaev's solution to the very same problem. We concludethat the magnetic field expressions given by Jones and Smyshlyaevcoincide, but a singular term is missing from Smyshlyaev's expressionfor the electric field. 相似文献
9.
Goodman TNT; Micchelli CA; Rodriguez G; Seatzu S 《IMA Journal of Numerical Analysis》1998,18(3):331-354
It is shown that, under certain conditions, orthonormalizingthe positive integer shifts of an exponentially decaying functionon the half line by the Gram-Schmidt process leads to a limitingprofile given by orthonormalizing all their integer shifts onthe whole line. These results derive from properties of Choleskyfactorization of bi-infinite and semi-infinite matrices. Anexample is provided by the negative exponential function andconjectures are given, supported by numerical evidence, forthe Gaussian and Lorentz function. 相似文献
10.
I. Havezov E. Ivanova P. Koehler N. Jordanov R. Matchat K. Reiher G. Emrich und K. Licht 《Fresenius' Journal of Analytical Chemistry》1987,326(6):536-539
Zusammenfassung Es wurden Verfahren zur Bestimmung dieser 10 Elemente in Ammoniumphosphat bzw. Phosphorsäure entwickelt. Zur Anreicherung wurde die Extraktion der Dithiocarbamate, 8-Hydroxychinolinate und Pyrazolonate der Elemente angewendet. Die Bestimmung der Elementkonzentrationen erfolgte mittels Flammen-AAS und OES. Die nach den verschiedenen Verfahren erhaltenen Ergebnisse sind in guter Übereinstimmung. Die Nachweisgrenzen der einzelnen Elemente liegen, abhängig vom Verfahren, zwischen 1.10–5 und 5.10–8%.
Determination of microtraces of Bi, Co, Fe, In, Mn, Ni, Pb, Cu, Sb and Zn in phosphoric acid and ammonium phosphate.I. Flame atomic absorption and optical emission spectroscopic determination after preconcentration of the microtraces by extraction
Summary Two different methods are applied to the determination of the trace element content in ammonium phosphate, or phosphoric acid, respectively. The procedures involve two separate extraction systems based on ammonium pyrrolidine-dithiocarbamate, 8-hydroxyquinoline and 1-phenyl-3-methyl-4-benzoylpyrazolone-5, and two spectroscopic techniques — AAS and OES. The results obtained by the different methods are in good agreement. The detection limits of the separate trace elements vary from 1×10–5 to 5×10–8%.相似文献