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951.
María Virginia Mirífico José Alberto Caram Oscar Enrique Piro Enrique Julio Vasini 《Journal of Physical Organic Chemistry》2007,20(12):1081-1087
The first nucleophilic addition of an inorganic nucleophile (cyanide) to the activated, rigid, α‐diazomethine groups of a 1,2,5‐thiadiazole 1,1‐dioxide is reported here. An α‐amino nitrile and a bis α‐amino nitrile derivatives were obtained in good yields (62 and 98%, respectively) and characterized by spectroscopic, analytical, and single crystal X‐ray diffraction techniques. The course of the reaction, followed by cyclic voltammetry (CV), showed that cyanide adds to only one of the two C?N double bonds of the thiadiazole, forming an anion from which an N‐methyl derivative was obtained. Adequate concentrations of cyanide and methyl iodide (MeI) produced directly the bis α‐amino nitrile derivative. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
952.
Javier Gamboa Félix Javier Jiménez-Jiménez Alberto Nieto Jose Montojo Miguel Ortí-Pareja José Antonio Molina Esteban García-Albea Ignacio Cobeta 《Journal of voice》1997,11(3):314-320
To quantify several acoustic features of the voice in patients withParkinson's disease (PD), 41 patients and 28 age and sex-matched controls were studied. PD severity was assessed with the Unified PD Rating Scale (UPDRS) and the Hoehn and Yahr staging. The Computerized Speech Lab 4300 program (Kay Elemetrics) was used. Two seconds of a sustained /a/ and a sentence were captured with a microphone and laryngograph equipment. Measures included fundamental frequency (FO), frequency perturbation (fitter), intensity perturbation (shimmer), and harmonic/noise ratio (H/N) of the vowel /a/, and frequency and intensity variability of a sentence, phonational range, dynamic range at the natural frequency, maximum phonational time and s/z ratio. All subjects underwent indirect laryngoscopy and/or laryngeal fibroscopy. When compared with controls, PD patients showed higher jitter, lower H/N ratio, lower frequency and intensity variability of the sentence, and lower phonational range and reported a higher frequency of the presence of low voice-intensity, monopitch, voice arrests, and struggle. These features seem to be unaffected by the duration and severity of the disease. 相似文献
953.
The split cuts of Cook, Kannan and Schrijver are general-purpose valid inequalities for integer programming which include a variety of other
well-known cuts as special cases. To detect violated split cuts, one has to solve the associated separation problem. The complexity of split cut separation was recently cited as an open problem by Cornuéjols & Li CL01.
In this paper we settle this question by proving strong 𝒩𝒫-completeness of separation for split cuts. As a by-product we
also show 𝒩𝒫-completeness of separation for several other classes of inequalities, including the MIR-inequalities of Nemhauser and Wolsey and some new inequalities which we call balanced split cuts and binary split cuts. We also strengthen 𝒩𝒫-completeness results of Caprara & Fischetti CF96 (for
-cuts) and Eisenbrand E99 (for Chvátal-Gomory cuts).
To compensate for this bleak picture, we also give a positive result for the Symmetric Travelling Salesman Problem. We show how to separate in polynomial time over a class of split cuts which includes all comb inequalities with a fixed handle.
Received: October 23, 2000 / Accepted: October 03, 2001 Published online: September 5, 2002
Key words. cutting planes – separation – complexity – travelling salesman problem – comb inequalities 相似文献
954.
955.
Maria Vittoria Barbarulo Francesca Buiarelli Massino Ciardi Alberto Giarrusso Felice Rosati G. P. Cartoni 《Journal of separation science》1995,18(11):705-708
The metabolism of oxabolone cipionate, 17-(3-cyclopentyl-1-oxopropoxy)-4-hydroxyestr-4-en-3-one, a synthetic anabolic steroid, was investigated in man, the cumulative urinary excretion and the metabolism of the compounds being studied by GC-MS in both electron impact and chemical ionization modes. After administration by injection to volunteers, five different metabolities were detected in urine. The metabolites and the parent compound were detected in urine up to a week after administration. 相似文献
956.
Alberto Caprara Matteo Fischetti Paolo Toth Daniele Vigo Pier Luigi Guida 《Mathematical Programming》1997,79(1-3):125-141
Crew management is concerned with building the work schedules of crews needed to cover a planned timetable. This is a well-known
problem in Operations Research and has been historically associated with airlines and mass-transit companies. More recently,
railway applications have also come on the scene, especially in Europe. In practice, the overall crew management problem is
decomposed into two subproblems, called crew scheduling and crew rostering. In this paper, we give an outline of different
ways of modeling the two subproblems and possible solution methods. Two main solution approaches are illustrated for real-world
applications. In particular we discuss in some detail the solution techniques currently adopted at the Italian railway company,
Ferrovie dello Stato SpA, for solving crew scheduling and rostering problems. 相似文献
957.
958.
959.
We prove that for closed 2-calibrated manifolds there always exist Lefschetz pencil structures. This generalizes similar results for symplectic and contact manifolds. To cite this article: A. Ibort, D. Marti´nez Torres, C. R. Acad. Sci. Paris, Ser. I 339 (2004). 相似文献
960.