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261.
A. Lang B. Blättel W. Cassing V. Koch U. Mosel K. Weber 《Zeitschrift für Physik A Hadrons and Nuclei》1991,340(3):287-295
Within a covariant BUU-approach we simulate heavyion collisions at various bombarding energies from 400 MeV/u to 1 GeV/u. We evaluate locally the energymomentum tensorT
v
(x), and extract pressures, energydensities and temperatures. The connection of these thermodynamical quantities to experimental observables and their sensitivity to the equation of state is discussed. Furthermore, we investigate the question of local equilibration and evaluate the entropy produced in these reactions.Dedicated to Prof. Dr. P. Kienle on the occasion of his 60th birthday. Work supported by BMFT and GSI Darmstadt 相似文献
262.
U. Licht-Klagge und G. Wünsch 《Fresenius' Journal of Analytical Chemistry》1992,343(5):405-410
Zusammenfassung Die Entdeckung von Zusammenhängen in Faktensammlungen gehört zu den wesentlichen Tätigkeiten empirischer Wissenschaftler. Diese Art von wissenschaftlicher Entdeckung läßt sich mit formalen Systemen beschreiben und mit Computerprogrammen nachvollziehen. Sowohl Ansätze aus der Künstlichen Intelligenz als auch rein numerische Verfahren erweisen sich als geeignet. Damit ergeben sich neue Perspektiven für die wissenschaftliche Handhabung großer Datenmengen. Als Beispiel dient die Konzipierung des qualitativen Trennungsganges nach C. Remigius Fresenius.
Project REMIGIUS — On the (re-)discovery of chemically relevant structures in lots of facts
Summary The discovery of structures in collections of facts is one of the essential activities of empirical scientists. Suitable strategies can be described by formal methods and performed with computer programs. Concepts of artificial intelligence as well as methods of numerical computation can be applied. This offers new perspectives for scientific interpretation of collections of unstructured data. The paper compares clustering and inductive learning for the conception of the well known qualitative separation scheme of C. Remigius Fresenius.相似文献
263.
U. M. Dzhemilev A. G. Ibragimov A. B. Morozov R. R. Muslukhov G. A. Tolstikov 《Russian Chemical Bulletin》1992,41(6):1089-1093
A new stereoselective method is developed for the synthesis of 1-chloro-, 1-alkoxy-, and 1-N,N-dialkylaminoalumino-cyclopentanes from -olefins, metallic magnesium, and aluminum halides (AlCl3, RO-AlCl2, R2N-AlCl2) in the presence of catalytic amounts of Cp2ZrCl2 (Cp=5-C5H5). The products from hydrolysis and deuterolysis of the Al-substituted 3,4-dialkylaluminocyclopentanes (ACP) have the threo configuration.For Communication 8, see [1].Institute of Organic Chemistry, Urals Branch, Russian Academy of Sciences, 450054 Ufa. Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 6, pp. 1393–1397, June, 1992. 相似文献
264.
H. U. Burger Dipl.-Math. Professor Dr. U. Müller-Funk Professor Dr. H. Witting 《Mathematical Methods of Operations Research》1992,36(2):163-184
Summary There is an abundancy of problems in which no parametric model realistically describes the situation and in which, accordingly, we have to resort to nonparametric methods. As the numerical problems connected with nonparametric tests are becoming less and less important, rank tests, permutation tests and the like are becoming more and more part of the standard armatory of applied statisticians. The lack of tabulated critical values, for instance, should no longer be a serious objection against the use of permutation tests in practice; cf. Edgington (1987).The rationale underlying permutation and rank tests has been outlined in quite a number of text books and papers; cf. Fraser (1957), Lehmann (1959), Hájek-Sidák (1967) or Witting (1970). Roughly speaking, permutation tests are constructibel if the data can be condensed by means of a sufficient and complete statistic allowing for the proper kind of conditioning. Rank tests arise if the underlying problem is invariant with respect to (w.r.t.) a large group of transformations which leads to a maximal invariant statistic consisting of (signed) ranks.Most practical nonparametric problems, however, are too complex to be tractable by just one of those approaches. Many of them, however, can be handled by a combination of both techniques. In this paper we outline the logic underlying that combined reduction method and apply it to construct locally most powerful tests. Moreover, we discuss what we label Hoeffding's transfer problem, i.e. the uniformity aspect of locally most powerful tests with respect to the starting point at the boundary. We are concentrating on the discussion of the nonparametric two-sample location and scale problem. Further important problems are mentioned in Section III.This is a written account of an invited lecture delivered by the third author on occasion of the 14th Symposium über Operations Research, Ulm, September 6–8, 1989. 相似文献
265.
Summary 1. The physical and chemical properties and the fatty-acid and glyceride compositions of the oils of four plants of the family Malvaceae have been studied. They all belong to the palmito-oleo-linoleic group.2. Their glyceride structure does not correspond to the principle of statistical distribution, since almost all the unsaturated-acid radicals are concentrated in the position.Order of the Red Banner of Labor Institute of the Chemistry of Plant Substances of the Academy of Sciences of the Uzbek SSR. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 252–255, May–June, 1971 相似文献
266.
A potassium electrode utilizing a solution of valinomycin in diphenylether and a porous membrane is compared with selectrodes in which the diphenylether has been replaced by a suitable plasticizer and the porous membrane support by a polymer net-work. The development of the polymer membrane allows the use of simplified selectrode construction with a “solid-state” calomel reference system; Rules for a successful choice of a suitable solvent-polymer combination are suggested and used for development of new Polyvinylchloride- and polyurethane-based membranes. 相似文献
267.
Reaction of dienamine 4a with substituted phenacyl bromides gave steroidal[3,4-b] furans 5a–g. The same principle reaction was utilized for the total synthesis of (±) 2 - (p - chlorophenyl) - 3 - oxa - A - nor - estra - 1,5(10), 9(11) - triene - 17 - acetate 12a. Treatment of 4a, b with benzenediazonium salts, in DMF, followed by a Fischer-indole cyclization yielded steroidal[6, 7-b] indoles 8a–k. Dienamine 4b could be annelated to benz[4, 5, 6] steroids 9a and 9b by reaction with methyl vinyl ketone and crotonaldehyde, respectively. 相似文献
268.
The luminescence of solid xenon at 20 K has been excited optically in the wavelength range 1550Åto 1150Å. The 1760Å emission band due to a transition of the molecule is found in agreement with α? or e?-excitation. The excitation spectrum yields a relatively high quantum efficiency of the Γ(3/2) exciton series indicating efficient self-trapping. The Γ(1/2) exciton series and conduction band states have a low quantum efficiency. 相似文献
269.
[reaction: see text] Treatment of the oxiranyl carbaldimine with base (LDA or LDA/KOtBu) leads in an one-step procedure to the polyfunctionalized aziridine. This highly diastereoselective reaction is explained by a new type of an Aza-Darzens reaction, in which one enantiomer of the starting material is deprotonated to form an oxiranyl anion, which attacks the imine carbon atom of the other enantiomer (mutual kinetic resolution by double diastereofacial selection). 相似文献
270.
L. M. Khalilov O. V. Shitikova R. I. Khusnutdinov Z. S. Muslimov U. M. Dzhemilev A. A. Panasenko G. A. Tolstikov 《Russian Chemical Bulletin》1990,39(3):484-488
The structures of the dimerization products of spiro(bicyclo[2.2.1]hepta-2,5-diene-7,1-cyclopropane) have been solved using13C NMR spectroscopy and their stereochemical assignments made. The methylene carbon atom signals for the spirocyclopropane fragment can be used as diagnostic signals in making the stereochemical assignments.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 559–564, March, 1990. 相似文献