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Gerhard Buchbauer Waltraud Pernold Dorothea Rassl Brigitte Blach 《Monatshefte für Chemie / Chemical Monthly》1981,112(4):517-527
The synthesis of some new potentially, nitrogenefree spasmolytics is described. Formally the benzene nucleus in some mandelic acid esters, known by their mild spasmolytic activity, is substituted for the isocamphane bicyclus by a) SeO2 oxidation of 1-(3,3-Dimethyl-2-exo-norbornyl)-ethanone (5) to the corresponding ketoaldehyde6, b) oxidation of6 to the isocamphane analogous mandelic acid4 and c) esterification of derivatives of4 with isoamylalcohol and benzylalcohol. Attemps to dehydrate the methylester7 to camphenylideneacetic acid methylester (12) by various methods failed, probably because of the ring strain.
Teil der Diplomarbeit vonB. Blach, Universität Wien 1981. 相似文献
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A chiral supramolecular assembly encapsulates the two cationic ruthenium sandwich complexes [CpRu(eta(6)-C(6)H(6))](+) and [CpRu(p-cymene)](+). The host-guest complexes K(11)[CpRu(eta(6)-C(6)H(6)) subset Ga(4)L(6)] (2) and K(11)[CpRu(p-cymene) subset Ga(4)L(6)] (3) were characterized by one- and two-dimensional NMR techniques as well as by electrospray mass spectrometry. Encapsulation of the prochiral complex [CpRu(p-cymene)](+) by the chiral host renders enantiotopic protons diastereotopic as evidenced by (1)H NMR spectroscopy. 相似文献
5.
Fiedler D Leung DH Bergman RG Raymond KN 《Journal of the American Chemical Society》2004,126(12):3674-3675
A supramolecular metal-ligand assembly encapsulates a variety of cationic half-sandwich ruthenium complexes. Due to the chirality of both host and guest, chiral recognition is observed with diastereomeric excesses up to 70%. The chiral cavity can be used to carry out a dynamic resolution of the rapidly equilibrating enantiomers of the chiral organometallic guest. 相似文献
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Niko Kivel Dorothea Schumann Ines Günther-Leopold 《Analytical and bioanalytical chemistry》2013,405(9):2965-2972
In many scientific fields, the half-life of radionuclides plays an important role. The accurate knowledge of this parameter has direct impact on, e.g., age determination of archeological artifacts and of the elemental synthesis in the universe. In order to derive the half-life of a long-lived radionuclide, the activity and the absolute number of atoms have to be analyzed. Whereas conventional radiation measurement methods are typically applied for activity determinations, the latter can be determined with high accuracy by mass spectrometric techniques. Over the past years, the half-lives of several radionuclides have been specified by means of multiple-collector inductively coupled plasma mass spectrometry (MC-ICP-MS) complementary to the earlier reported values mainly derived by accelerator mass spectrometry. The present paper discusses all critical aspects (amount of material, radiochemical sample preparation, interference correction, isotope dilution mass spectrometry, calculation of measurement uncertainty) for a precise analysis of the number of atoms by MC-ICP-MS exemplified for the recently published half-life determination of $^{60}$ Fe (Rugel et al, Phys Rev Lett 103:072502, 2009). 相似文献
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D. Bahns S. Doplicher K. Fredenhagen G. Piacitelli 《Communications in Mathematical Physics》2003,237(1-2):221-241
We discuss a formulation of quantum field theory on quantum space time where the perturbation expansion of the S-matrix is term by term ultraviolet finite.
The characteristic feature of our approach is a quantum version of the Wick product at coinciding points: the differences
of coordinates q
j
−q
k
are not set equal to zero, which would violate the commutation relation between their components. We show that the optimal
degree of approximate coincidence can be defined by the evaluation of a conditional expectation which replaces each function
of q
j
−q
k
by its expectation value in optimally localized states, while leaving the mean coordinates invariant.
The resulting procedure is to a large extent unique, and is invariant under translations and rotations, but violates Lorentz
invariance. Indeed, optimal localization refers to a specific Lorentz frame, where the electric and magnetic parts of the
commutator of the coordinates have to coincide [11].
Employing an adiabatic switching, we show that the S-matrix is term by term finite. The matrix elements of the transfer matrix
are determined, at each order in the perturbative expansion, by kernels with Gaussian decay in the Planck scale. The adiabatic
limit and the large scale limit of this theory will be studied elsewhere.
Received: 15 January 2003 / Accepted: 20 March 2003
Published online: 5 May 2003
RID="*"
ID="*" Research supported by MIUR and GNAMPA-INDAM
RID="*"
ID="*" Research supported by MIUR and GNAMPA-INDAM
Communicated by H. Araki and D. Buchholz 相似文献