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61.
Peter Johansen 《BIT Numerical Mathematics》1988,28(3):573-580
An algorithm is presented for inductive inference of ultimately periodic sequences. It can be implemented in linear time and space.Dedicated to Peter Naur on the occasion of his 60th birthday 相似文献
62.
Samples of human faeces from patients suffering from intestinal bleeding have been studied by use of Mössbauer spectroscopy. It is shown that it is possible to follow the degradation of blood in the digestive tract. 相似文献
63.
The concept of a branch weight centroid has been extended in [12] so that it can be defined for an arbitrary finite setX with a distinguished familyC of "convex" subsets ofX. In particular, the centroid of a graphG was defined forX to be the vertex setV(G) ofG andU V(G) is convex if it is the vertex set of a chordless path inG. In this paper, which is an extended version of [13], we give necessary and sufficient conditions for a graph to be a centroid of another graph as well as of itself. Then, we apply these results to some particular classes of graphs: chordal, Halin, series-parallel and outerplanar.This research has been partly supported by Grant RP.I.09 from the Institute of Computer Science, University of Warsaw. This paper was completed when the second author was at Fachbereich 3 -Mathematik, Technische Universität Berlin, supported also by the Alexander von Humboldt-Stiftung (Bonn). 相似文献
64.
Ab initio LCAO-MO-SCF calculations using a double zeta basis set have been performed for the methyl esters of acetic acid, carbamic acid, methylcarbonic acid, and trifluoracetic acid, in order to model the corresponding choline esters. The systems have been compared by means of population analyses, electron density differences, electrostatic potentials and potential differences. The significance of the electrostatic potential in connection with crystal structure and packing has been studied. The differences in the proton affinity of the compounds have been correlated to differences in the potentials. 相似文献
65.
Introduction of aryl and heteroaryl substituents into the 5-position of 3-benzyloxyisothiazole (1) using palladium-catalyzed Suzuki and Negishi cross-coupling reactions was investigated. Attempts to generate synthetically viable nucleophilic species from 1 for Suzuki- or Negishi-type cross-couplings were unsuccessful. However, using 3-benzyloxy-5-iodoisothiazole 2 as an intermediate, a range of aromatic and heteroaromatic substituents were successfully introduced under Suzuki or Negishi cross-coupling conditions in good to excellent yields. 相似文献
66.
Abstract— Some photochemical and photophysical properties of a group of xanthene dyes have been studied in relation to their roles as sensitizers for the photoreduction of water. New spectroscopic and kinetic measurements have been carried out with these dyes. The triplet states of the dyes undergo energy-transfer and electron-transfer, but with rate constants differing by two orders of magnitude in favour of the former pathway. The very efficient transfer of triplet energy from a group of dyes to an acceptor molecule led to the design of a greatly improved system for the photochemical production of hydrogen. 相似文献
67.
E. Steinnes O. R. Birkelund O. Johansen 《Journal of Radioanalytical and Nuclear Chemistry》1971,9(2):267-272
Solvent extraction with TOPO from 6M hydrochloric acid is proposed as a method for the elimination of interfering activities in neutron activation analysis of
biological material for trace elements. By this procedure24Na,42K,32P,82Br, and47Ca are efficiently removed, and a number of trace element activities can be measured by Ge(Li) spectrometry. Chemical yields
are determined by re-activation. Data for Cu, Zn, Mo, and Cd in two biological standards are presented. 相似文献
68.
Rastogi SC Zachariae C Johansen JD Devantier C Menné T 《Journal of chromatography. A》2004,1031(1-2):315-317
An increased frequency of contact allergy to methyldibromoglutaronitrile (MDBGN), a commonly used preservative in cosmetics and other consumer products, has been reported in recent years. A high-performance liquid chromatography (HPLC) method for the determination of MDBGN in cosmetic products has been validated in the present study. The identification is performed by reductive electrochemical detection of the bromine present in the molecule. The method is suitable for compliance testing of cosmetic products as well as for the research to support clinical and epidemiological studies. 相似文献
69.
Sanyalak Niratisairak Tom H. Johansen Susumu Katouda Takayuki Ishibashi 《Physica C: Superconductivity and its Applications》2011,471(7-8):222-225
Two voltage jumps were found in the current–voltage characteristic of a thin superconducting film of Bi2Sr2CaCu2Ox at temperature 58 K. The fluorescent thermal imaging technique revealed a localized heat dissipation (hotspot) nucleated at the current causing the second jump, and the hotspots’ temperature is close to the critical temperature of the superconducting film. 相似文献
70.
A. A. Semenov S. F. Karmanenko A. A. Melkov A. V. Bobyl’ R. A. Suris Yu. M. Gal’perin T. H. Johansen 《Technical Physics》2001,46(10):1218-1224
An electrodynamic model that describes the dispersion of magnetostatic surface waves in ferrite/superconductor structures is suggested. On its basis, a new approach to determining the microwave sheet resistance R S of superconducting films in a magnetic field is elaborated. The values calculated (R S =0.20–0.96 mΩ) agree with results obtained by the Tauber method. For YIG/YBCO structures, the controllable phase shift is about 1.5π when the depth of magnetostatic wave penetration into the YBCO film varies from 2.0 to 0.8 μm. 相似文献