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1.
We construct for each n2 an isometric C-imbedding HnE6n–6 of the n-dim. hyperbolic space into the Euclidean space E6n–6 whose image is the graph of a C-map RnR5n–6. This generalizes a well known result of D. Blanusa 1955 (the case n=2). 相似文献
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The quantitative determination of the quaternary spasmolytic compound ciclotropium and its metabolite N-isopropyltropinium is described for human plasma and urine. The analytical procedure consists of ion-pair extraction from biological material, alkaline hydrolysis, subsequent derivatization with the fluorophor flunoxaprofen chloride and separation by high-performance liquid chromatography on a reversed-phase column with fluorimetric monitoring. The detection limits of 0.5 ng/ml in plasma and 10 ng/ml in urine at signal-to-noise ratios higher than 3 permit the determination of pharmacokinetic parameters after therapeutic doses. 相似文献
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Rudolf Allmann Wolfgang Henke Peter Krommes Jörg Lorberth 《Journal of organometallic chemistry》1978,162(3):283-287
The molecular and crystal structure of tris(bistrimethylsilylamin)thallium was determined by means of single-crystal X-ray spectroscopy: in the space group P1c with a = 16.447(7), c = 8.456(7) Å; and Dc = 1.149 g cm?3 two molecules are located in the unit cell. The compound is isomorphous to the analogues Fe[N(SiMe3)2]3 or Al[N(SiMe3)2]3, respectively, which show a propellar-twist of the Si2N-groups versus the plane of the metal atom and the three nitrogen-atoms: Tl(N)3/Si2N 49.1°; SiNSi 122.6°; NSiC 111.8°; CSiC 107.1°; TlN 2.089 Å;; SiN 1.738 Å;; 1.889 Å;. 相似文献
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Henning Henke 《无机化学与普通化学杂志》1993,619(2):311-317
Crystal Structure and Pseudosymmetry of a New Modification of Potassium Hexachloroniobate(V), KNbCl6. Comments on the Cubic Phase Long needles of KNbCl6 – invariably twinned around [100] – are obtained if the material is crystallized from SOCl2 solution. The structure has been determined from X-ray data collected with a single-crystal diffractometer at room temperature [space group P21/n, Z = 16, a = 6.894(1), b = 22.073(4), c = 23.337(3) Å, β = 91.00(1)°, R = 0.032 for 2 909 unique reflexions, 290 structural parameters]. Distorted NbCl6? octahedra and ?interstitial’? K+ ions are found to form similar arrangements, each of them corresponding to a closest packing of spheres with the layer sequence ACAB (stacking symbol hc). The resulting asymmetry in coordination by potassium is coupled with a strong off-centre displacement of the Nb atoms in any of the four independent chlorine polyhedra (0.14 Å on average). A pronounced pseudosymmetry accounts for the twinning. Since P21/m21/n21/b (no. 62) is already a good approximation of the real structure, only one formal step of symmetry reduction (index t2) is needed to create both, the observed twin law and the actual space group P1 21/n1. Above 180°C a reconstructive phase transition leads to the ‘face-centred cubic’ modification with ~ 10% lower density. 相似文献
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S. Schweizer B. Henke P.T. Miclea B. Ahrens J.A. Johnson 《Radiation measurements》2010,45(3-6):485-489
Thermal processing of as-made fluorozirconate glasses, which were additionally doped with rare-earth and chlorine ions, results in the formation of fluorescent nanocrystals therein. For medical applications, the glasses were doped with divalent europium ions as the fluorescent rare-earth ion, while trivalent neodymium was used to develop up-conversion systems. The samples were annealed up to 290 °C to initiate the growth of hexagonal or orthorhombic phase BaCl2 nanocrystals therein. Upon annealing some of the rare-earth ions were incorporated into the BaCl2 nanocrystals leading to enhanced fluorescence properties. The particle diameters were in the range of a few nanometers to several tens of nanometers. 相似文献
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Christian Schenk Florian Henke Andreas Schnepf 《Phosphorus, sulfur, and silicon and the related elements》2013,188(6):1370-1374
Abstract Metalloid cluster compounds of group 14 of the general formulae EnRm with n > m (E = Si, Ge, Sn, Pb; R = ligand), where naked as well as ligand bound tetrel atoms are present, represent a novel class of cluster compounds in group 14 chemistry and can be seen as intermediates on the way to the elemental state. Therefore, interesting properties are expected for these compounds, which might complement results from nanotechnology. In this article, first results for germanium are discussed, together with novel build-up reactions on the way to novel materials based on metalloid cluster compounds. GRAPHICAL ABSTRACT 相似文献
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