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71.
J. Bartel D. Boosé K. Dietrich K. Pomorski J. Richert 《Zeitschrift für Physik A Hadrons and Nuclei》1991,339(1):155-170
Giant shape vibrations of fission fragments are described in a simple model which is based on nuclear transport theory. The friction and inertial parameters are calculated within the linear response and cranking theory, respectively. The initial conditions are chosen in the scission region following the conventional picture of the fission process at low energy. The emission of electromagnetic radiation by the form vibration is treated classically.Dedicated to Prof. Dr. H.J. Mang on the occasion of his 60th birthday 相似文献
72.
73.
Dietrich Lortz Rita Mayer-Spasche W. Trnig 《Mathematical Methods in the Applied Sciences》1982,4(1):425-432
Lower bounds for the real parts of the points in the spectrum of elliptic equations are derived. These bounds, depending only on the diameter L of the domain G and on the maximum norm M of the coefficients a, b, are optimal. They are always positive and thus the spectrum is bounded away from the imaginary axis. This result is then used to prove an “anti-dynamo theorem” for magnetic fields with plane symmetry in the case of a compressible steady flow surrounded by a perfect conductor. 相似文献
74.
Dietrich Mootz Reinhard Seidel 《Journal of inclusion phenomena and macrocyclic chemistry》1990,8(1-2):139-157
The tetramethylammonium hydroxide-water system has been studied by low-temperature differential thermal analysis and X-ray powder diffraction. The melting diagram was constructed for concentrations between 66.7 and 100 mol% H2O. It shows the existence and stability ranges of as many as eight crystalline hydrate phases:- and-Me4NOH·2H2O (phase transition at –85°C, decomposition atca. 105°C), Me4NOH·4 H2O (melting point 44°C, incongruent), and-Me4NOH·5 H2O (phase transition at 42°C, melting point 68°C, congruent),- and-Me4NOH·7.5 H2O (phase transition at 6°C, melting point 16°C, incongruent), and Me4NOH·10 H2O (melting point –20°C, incongruent). The structures of all these phases, except the already known one of-Me4NOH·5 H2O, were determined from single-crystal MoK diffractometer data. The decahydrate and the high-temperature forms of the 7.5-hydrate and the pentahydrate are genuinepolyhedral clathrate hydrates, the first ones reported of a strong base. Their mostly novel three-dimensional anionic host structures, formed by the hydrogen-bonded OH– ions and H2O molecules, arefour-connected throughout, in spite of their proton deficiency which is apparently leveled by disorder. Disorder also affects the enclosed cationic Me4N+ guest species. Like the low-temperature form of the pentahydrate, that of the 7.5-hydrate has a clathrate-related, but not fully polyhedral structure, some of the oxygen atoms being three-connected only. The tetrahydrate presents the rare case of both a hydrogen bond of the type OH–...OH2 and a (deprotonated) water-channel structure. This is fully ordered and apart from that can be derived from the polyhedral one of the-pentahydrate just by removing the appropriate number of water molecules from certain positions. The structures of- and-Me4NOH·2 H2O contain identical one-dimensionalspiro chains [HO–(HOH)/42] with the hydroxide protonnot participating in the hydrogen bonding. The Me4N+ ion is ordered in the and disordered in the phase.Supplementary Data relating to this article are deposited with the British Library as Supplementary Publication No. SUP 82076 (66 pages).Dedicated to Dr D. W. Davidson in honor of his great contributions to the sciences of inclusion phenomena. 相似文献
75.
A synthesis of 5,11b-dihydro-1H-dibenzo[d,f][1,3]diazepin-1-ones was found in the reaction of nitro-substituted N1,N2-diarylamidines with 3,4,5,6-tetrachloro-1,2-benzoquinone. In contrast, 6,7,8,9-tetrachlorodibenzodioxins were obtained from reaction of N1,N2-diphenylpropionamidine and N1,N2-di-(4-tert-butylphenyl)acetamidine with 3,4,5,6-tetrachloro-1,2-benzoquinone. 相似文献
76.
Alkoxylierung von bis(trimethylsilyl)-aminofluorsilanen,sowie siloxanbildung unter äthereliminierung
Uwe Klingebiel Dietrich Fischer Anton Meller 《Journal of organometallic chemistry》1975,85(2):141-147
The reaction of bis(trimethylsilyl)aminofluorsilanes, (Me3Si)2NSiF2R (R = CH3 or F), with sodium alcoholates or sodium phenylate yields under elimination of NaF alkoxy- and aryloxy-aminofluorosilanes of the composition (Me3Si)2NSiF(R)OR′(R′ = CH3, C2H5, C3H7, C6H5). A disiloxane is formed by thermal elimination of diethyl ether from bis(trimethylsilyl)aminomethylfluoroethoxysilane. The IR, mass, 1H and 19F NMR spectra of the above-mentioned compounds are reported. ab]Die Reaktion von Bis(trimethylsilyl)-aminofluorsilanen des Typs (Me3Si)2NSiF2R (R = F, CH3) mit Natriumalkoholaten und Natriumphenolat führt unter NaF-Abspaltung zu Alkyl- und Aryloxyaminofluorsilanen der Zusammensetzung: (Me3Si)2NSiF(R)OR′ (R′ = CH3, C2H7, C6H5, C6H5). Ein Disiloxan könnte durch die thermische Eliminierung von Diäthyläther aus Bis(trimethylsilyl)aminomethyl-fluor-äthoxy-silylarnin erhalten werden.Die IR-, Massen-, 1H- und 19F-NMR-Spektren der dargestellten Verbindungen werden mitgeteilt. 相似文献
77.
Crystal Structures of Acid Hydrates and Oxonium Salts. XX. Oxonium Tetrafluoroborates H3OBF4, [H5O2]BF4, and [H(CH3OH)2]BF4 The crystal structures of three oxonium tetrafluoroborates were determined. H3OBF4, oxonium tetrafluoroborate proper, is triclinic with space group P1 , Z = 2 and the unit cell dimensions a = 4.758, b = 6.047, c = 6.352 Å and α = 80.40, β = 79.48, γ = 88.25° at ?26°C. Cations H3O+ and anions BF4? are linked by hydrogen bonds O? H…?F into ribbons of condensed rings. In [H5O2]BF4 (diaquohydrogen tetrafluoroborate, monoclinic, P21/c, Z = 4, a = 6.584, b = 9.725, c = 7.084 Å, β = 95.15° at ?100°C) the hydrogen bond in the cation H5O2+ is 2.412 Å short, asymmetric and approximately centered and the linking of cations and anions three-dimensional. In [H(CH3OH)2]BF4 (Bis(methanol)hydrogen tetrafluoroborate, monoclinic, P21/c, Z = 4, a = 5.197, b = 14.458, c = 9.318 Å, β = 94.61° at ?50°C) the cation [H(CH3OH)2]+ is characterized for the first time in a crystal structure with an again very short (2.394 Å), asymmetric and effectively centered hydrogen bond. By further hydrogen bonds cations and anions form only dimers of the formula unit of centrosymmetric cyclic structure. 相似文献
78.
Neumann M Herten DP Dietrich A Wolfrum J Sauer M 《Journal of chromatography. A》2000,871(1-2):299-310
The first capillary array scanner for time-resolved fluorescence detection in parallel capillary electrophoresis based on semiconductor technology is described. The system consists essentially of a confocal fluorescence microscope and a x,y-microscope scanning stage. Fluorescence of the labelled probe molecules was excited using a short-pulse diode laser emitting at 640 nm with a repetition rate of 50 MHz. Using a single filter system the fluorescence decays of different labels were detected by an avalanche photodiode in combination with a PC plug-in card for time-correlated single-photon counting (TCSPC). The time-resolved fluorescence signals were analyzed and identified by a maximum likelihood estimator (MLE). The x,y-microscope scanning stage allows for discontinuous, bidirectional scanning of up to 16 capillaries in an array, resulting in longer fluorescence collection times per capillary compared to scanners working in a continuous mode. Synchronization of the alignment and measurement process were developed to allow for data acquisition without overhead. Detection limits in the subzeptomol range for different dye molecules separated in parallel capillaries have been achieved. In addition, we report on parallel time-resolved detection and separation of more than 400 bases of single base extension DNA fragments in capillary array electrophoresis. Using only semiconductor technology the presented technique represents a low-cost alternative for high throughput DNA sequencing in parallel capillaries. 相似文献
79.
The oxygen chemisorption on Ni, Cu and Ag is studied by comparing PE spectra of these systems and SCF-Xα scattered-wave cluster models. Consideration of octahedral clusters M6 (M = Ni, Cu, Ag) shows that they are large enough to reproduce trends in energy differences, such as the width of the d-bands and the distance from the top of the d-bands to the Fermi level, as found in experiment and in bulk energy band calculations. Substrate model clusters for the interaction of oxygen with different metal surfaces are derived from an octahedron by removing one ((100) face) or two adjacent metal atoms ((110) face). Comparing the UPS difference spectrum for O/Ag (110) with several Ag4O cluster models makes it possible to interpret the peaks above the Ag d-band as O-Ag anti-bonding levels. These peaks are caused by O 2p-Ag 4d and O 2p-Ag 5s interaction. The corresponding bonding levels fall in the Ag d-bands and cannot therefore be identified with confidence in the spectra. The decreasing intensity of the oxygen derived peak below the metal d-band in the UPS spectra when going from Ni to Cu to Ag, and the simultaneously increasing O peaks above the d-band correlate with the changes of the localization of the corresponding bonding and anti-bonding levels in the oxygen sphere and the decreasing strength of the chemisorption bond. 相似文献
80.
Soliton physics has made considerable progress in solving nonlinear problems. This paper is meant to relate the soliten concept to the stationary axisymmetric vacuum fields in general relativity. We present a functional transformation which, working as a nonlinear creation operator, generates gravitational fields of isolated sources. When applied to flat space-time (gravitational vacuum) this operation leads to a nonlinear superposition of an arbitrary number of Kerr particles. This superposition also includes the Tomimatsu-Sato fields. The functional transformations form an infinite-parameter group which contains the Kinnersley-Geroch group as a subgroup.This essay received the second award from the Gravity Research Foundation for the year 1980.-Ed. 相似文献