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51.
52.
Grzegorz Zi?ba Marcin Rojkiewicz Violetta Kozik Krystyna Jarzembek Anna Jarczyk Aleksander Sochanik Piotr Ku? 《Monatshefte für Chemie / Chemical Monthly》2012,58(4):153-159
Abstract
A series of mono-alkylcarboxylic acid derivatives of tetraphenylporphyrin have been prepared. All the porphyrins were completely characterized by use of mass, 1H NMR, UV–visible, and fluorescence spectroscopy. Experimental log P were determined by use of reversed-phase thin-layer chromatography with use of log P Rekker. These porphyrins are potential photosensitizers in photodynamic therapy. 相似文献53.
Zbigniew Ka?u?a Arkadiusz KazimierskiKrzysztof Lewandowski Kinga SuwińskaBeata Szcz?sna Marek Chmielewski 《Tetrahedron》2003,59(31):5893-5903
Starting from (l)-ethyl lactate and 4-vinyloxy-azetidin-2-one the diastereomeric (4S,6R)- and (4S,6S)-4-methyl-5-oxa-3-methylene and 3-oxo-cephams were obtained. The formation of the cepham skeleton proceeds with a diastereomeric excess up to 80%, depending on catalyst and reaction conditions. For comparison, the corresponding racemic cephams lacking a methyl at C-4 or with a gem-dimethyl group at C-4 were synthesized. 相似文献
54.
Jȩdrzej Śniatycki 《Reports on Mathematical Physics》1984,19(3):407-422
The space C of Cauchy data essentially consists of all Cauchy data on all Cauchy surfaces for the field theory under consideration. There is a canonically defined distribution on C, the integral manifolds of which represent the histories of the field. This formulation of field theory is purely intrinsic in contradistinction to the standard Hamiltonian formulation which requires a 3 + 1 splitting of the space time. 相似文献
55.
Marek Krȩglewski 《Journal of Molecular Spectroscopy》1984,105(1):8-23
The rotation-bending-internal rotation Hamiltonian for quasi-symmetric top molecules with a single rotor [A. Wierzbicki, J. Koput, and M. Kr?glewski, J. Mol. Spectrosc.99, 102–115 (1983)] is used to calculate the correlation diagrams between the energy levels of the SiH3NCO-type molecules in the symmetric and asymmetric top limits, and to predict various features of the microwave spectrum through trial calculations. The height of the barrier to linearity was varied from 0 to 6500 cm?1. For the barriers 0, 31, and 139 cm?1, the effects of hindered internal rotation are studied and several (Δl = 3, Δk = 0) resonances are found. In some cases almost all the microwave transitions from a given vibrational state can be perturbed. 相似文献
56.
K. Ziȩtak 《Journal of Computational and Applied Mathematics》1984,11(3):297-305
In this paper we investigate a connection between lp-approximation and the Chebyshev approximation of a rectangular matrix by matrices of smaller rank. We consider also the stationary points of problems (4) and (5) which are connected with these approximations. 相似文献
57.
Violetta Cecchetti Arnaldo Fravolini Fausto Schiaffella Oriana Tabarrini Weicheng Zhou Pier Giuseppe Pagella 《Journal of heterocyclic chemistry》1992,29(2):375-382
The synthesis of 1,4-benzothiazine-2-carboxylic acid 1-oxides as agents which mimic quinolone antibacterial, are described. The key step includes intramolecular cyclization of phenylsulfinyl acrylates 17 and 18 which are prepared in six steps from 11. None of new target compounds showed interesting antibacterial activity in vitro against the tested strains. 相似文献
58.
59.
The adhesive energies between densely packed planes of simple metal slabs are calculated as a function of separation. The assumed simple form of the electron density profile makes the calculation semianalytical and simple. Due to the improved treatment of the kinetic energy functional through the inclusion of the fourth-order density gradients, the results are in reasonable agreement with the results of self-consistent calculations and experiment. 相似文献
60.
In normal conditions, a pupil of the eye is observed through the optical system of the cornea. The cornea is the anterior surface of the eye and is the major refractive element of the human eye. The influence of the corneal shape should not be neglected in measurements of the pupil size. The purpose of this study was to estimate the influence of the corneal geometry, the diameter of the pupil and its position in the anterior chamber on the magnification and position of the image of the pupil. The numerical calculations presented in the paper assume infinitely thin cornea, and the corneal topography was approximated by the elongated ellipsoid. The ray tracing procedure was used in our numerical modelling. The magnification of the pupil image amounted to about 10% and increases with decrease of radius of curvature and eccentricity of the corneal profile and decreases for the largest pupil. The results show also that the pupil image is placed nearer the corneal apex than the real pupil. The image of the pupil is always blurred, which limits the sharp observation of the pupil. 相似文献