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  • Wiley-Blackwell  (37)
  • Blackwell Publishing Ltd  (6)
  • 1990-1994  (24)
  • 1985-1989  (19)
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Year
  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Geophysical prospecting 35 (1987), S. 0 
    ISSN: 1365-2478
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Physics
    Notes: Since the important contributions of Dürbaum and Dix, 30 years ago, velocity profile estimation procedures on horizontally layered and vertically heterogeneous media from seismic probing data have been based largely on hyperbolic moveout models and RMS and stacking velocity concepts. Re-examination of the fundamentals reveals that quantitative velocity heterogeneity and canonical valocity profiles have been implicit factors for moveout modelling and for profile inversion in the use of the Dix procedure. Heterogeneity h is the ratio (and vRMS the geometric or harmonic mean) of the path-average and time-average velocities for a raypath or, in a more restricted sense, for the normal ray belonging to a velocity profile. The canonical profile for a given velocity profile or profile segment is a moveout-equivalent monotonically increasing ramp-like profile.The ramp or constant gradient in depth is the simplest velocity profile approximator which can explicitly accommodate velocity heterogeneity. A ramp model structure is detailed which facilitates moveout simulation and model parameter estimation, and the parametric effects are explored. The horizontal offset range is quantified for which this model can give good moveout approximations.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 580 (1990), S. 0 
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 543 (1988), S. 0 
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Pediatric anesthesia 3 (1993), S. 0 
    ISSN: 1460-9592
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: This prospective study was undertaken to examine the safety and to review the historical antecedents of an alternative method of paediatric anaesthetic induction other than halothane by mask. Two-thousand and five ASA I, II and III patients, 1 month-16 years of age initially received 70% N2O in O2 via a flavour-scented mask for 1–3 min, until adequate sedation was achieved. Venous cannulation was then undertaken, followed by an intravenous induction with thiopentone, and either atracurium or suxamethonium. The anaesthetist noted the occurrence of specific critical incidents during induction: excitement, coughing, vomiting, airway obstruction, laryngospasm, bradycardia for age, hypotension and/or hypoxaemia. The frequencies of all eight specific critical incidents on induction were extremely low in all ages. The studied alternative method of paediatric anaesthetic induction may be safer and more applicable in diverse clinical settings than a conventional halothane mask induction.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: The uropathogenic Escherichia coli strain 536 possesses two large, unstable DNA regions on its chromosome, which were termed pathogenicity islands (pais). Deletions of pais, which occur with relatively high frequency in vitro and in vivo, lead to avirulent mutants. The genetic determinants for production of haemolysin (Hly) and P-related fimbriae (Prf) are located in one of these islands. Deletion of this pathogenicity isiand (paill) not only removes the hly- and prf-specific genes, but also represses S fimbriae (Sfa), although the sfa genes of this virulence factor are not located on paill. We have identified two regulatory genes, prfB and prfl, of the prf gene cluster that are homologous to the sfa regulatory genes staB and SfaC, respectively. Mutations in sfaB and sfaC that inhibit transcription of the major fimbrial subunit gene sfaA were complemented by the homologous prf genes, suggesting communication between the two fimbrial gene clusters in the wild-type strain. Chromosomal mutagenesis of the two prf regulators in strain 536 repressed transcription of sfaA, detected by Northern hybridization and a chromosomal sfaA-lacZ fusion. In addition, haemagglutination assays measured a lower level of S fimbriae in these mutants. Expression of the cloned prf regulators in trans reversed the effect of the mutations; furthermore, constitutive expression of prfB or prfl could also overcome the repression of S fimbriae in a strain that had lost the pathogenicity islands. Virulence assays in mice established that the prf mutants were less virulent than the wild-type strain. The results demonstrate that cross-regulation of two unlinked virulence gene clusters together with the co-ordinate loss of large DNA regions significantly influences the virulence of an extraintestinal E. coli wild-type isolate.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 42 (1993), S. 0 
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Hydrogen sulphide is a toxicant naturally produced in hypoxic marine sediments, hydrocarbon and brine seeps and hydrothermal vents. The California killifish, a salt marsh resident, is remarkably tolerant of sulphide. The 50% lethal concentration is 700 μM total sulphide in 96 h, and 5 mM in 8 h (determined in flow-through, oxygenated sea water). Killifish exposed to sulphide produce thiosulphate which accumulates in the blood. The cytochrome c oxidase (a major site of toxicity) of the killifish is 50% inhibited by 〈1 μM sulphide. Killifish liver mitochondria are poisoned by 50–75 μM sulphide but can oxidize 10–20 μM sulphide to thiosulphate. Sulphide causes sulphhaemoglobin formation (and impairment of oxygen transport) at 1–5 mM in vitro and to a small extent at 2 mM in vivo. Killifish blood neither catalyses sulphide oxidation significantly nor binds sulphide at environmental (low) sulphide concentrations. Exposure to 200 μM and 700 μM sulphide over several days causes significant increases in lactate concentrations, indicating shift to anaerobic glycolysis. However, individuals with the most lactate die. In terms of diffusible H2S, the killifish can withstand concentrations two to three orders of magnitude greater than would poison cytochrome c oxidase. The high sulphide tolerance of the killifish, particularly of concentrations typical of salt marshes, can be explained chiefly by mitochondrial sulphide oxidation. Sulphide tolerance and mitochondrial sulphide oxidation in the killifish have a constitutive basis, i.e. do not diminish in fish held in the laboratory in sulphide-free water for 1–2 months, and are improved by prior acclimation.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Separation and Quantitation of All Eight Stereoisomers of α-Tocopherol by ChromatographyThe results of the analysis of several derivatives of (all-rac)-α-tocopherol by HPLC on a chiral stationary phase and by capillary GC on a achiral stationary phase are reported. Consecutive application of both methods to the ethyl-ether derivative allows the separation and quantification of all eight possible stereoisomers of (all-rac)-α-tocopherol.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 121 (1988), S. 961-970 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis of [2]-Catenanes from [2]-RotaxanesStarting from the rotaxane 18a a mixture of catenane 21 and rotaxane 23 is obtained by attaching a polymethylene bridge between the methylene groups in α-position of the sulfonyl groups. The isocyclic catenane 28 containing a 28- and a 46-membered ring is obtained from the catenane 21 by splitting the bonds between the bridgehead atoms and the sulfonyl groups. The 1H-, 13C-NMR, and mass spectra of this compounds are discussed.
    Notes: Ausgehend von dem Rotaxan 18a wird durch Angliederung einer Polymethylenbrücke zwischen den beiden zu den Sulfonylgruppen α-ständigen Methylengruppen ein Gemisch von Catenan 21 und Rotaxan 23 synthetisiert. Aus 21 wird nach Spaltung der Bindungen zwischen den Brückenkopfatomen und den Sulfonylgruppen das isocyclische Catenan 28, bestehend aus einem 28-und einem 46-gliedrigen Ring, erhalten. Die 1H-, 13C-NMR-Spektren und Massenspektren dieser Verbindung werden diskutiert.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 119 (1986), S. 1374-1399 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Directed Synthesis of Translationally Isomeric [3]-Catenanes1)In a multi-step reaction sequence the tetrahydroxymetacyclophane 12c is synthesized. Acetalisation with 1,25-dichloro-13-pentacosanone followed by nitration and reduction afforded the diamine 13c. By cyclization of this compound in 2-pentanol with sodium carbonate and sodium iodide under high dilution conditions the monomeric products 16, 17, and 18 are obtained in yields of 21.4, 7.7, and 0.9%, respectively. On the basis of mass, 13C NMR and 1H NMR spectra the structure of these compounds is discussed. Starting from the precatenane 16 the [3]-catenanes 25a, b,c and 26a, b, c are obtained in a multi-step reaction sequence. The structure of these compounds is confirmed by mass, 13C NMR, and 1H NMR spectroscopic investigations.
    Notes: In einer vielstufigen Synthese wird das Tetrahydroxymetacyclophan 12c synthetisiert. Durch Acetalisierung mit 1,25-Dichlor-13-Pentacosanon, nachfolgender Nitrierung und Reduktion wird das Diamin 13c erhalten. Dessen Cyclisierung in 2-Pentanol in Gegenwart von Natriumcarbonat und Natriumiodid unter Verdünnungsbedingungen ergibt die monomeren Cyclisierungsprodukte 16, 17 und 18 in Ausbeuten von 21.4. 7.7 und 0.9%. Die Struktur dieser Verbindungen wird anhand der Massen-, 13C- und 1H-NMR-Spektren diskutiert. In einer mehrstufigen Reaktionsfolge werden aus dem Prä-[3]-catenan 16 die [3]-Catenane 25a, b, c und 26a, b, c erhalten. Die Struktur dieser Verbindungen wird durch 13C-NMR, 1H-NMR- und massenspektroskopische Untersuchungen bewiesen.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 327 (1985), S. 399-410 
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Photoinduced Electron Transfer between Arenediazonium Cations and AnionsAnions X⊖ can act as donors in electron transfer reactions to photoexcited arenediazonium ions. The yield of the arene formed in this reaction increases with decreasing electrochemical oxidation potential EoxD of X⊖ (X⊖ = BPh4⊖, Br⊖, HOOC—COO⊖, Cl⊖, BF4⊖). The oxidized donor X· (Cl·, ·COO⊖) and aryl radicals Ar· benig intermediates of the reductive dediazoniation of ArN2⊖ can be detected by spin trapping with nitrosodurene (ND) and phenyl-tert-butylnitrone (PBN). A solvent effect in the electron transfer reaction is interpreted in terms of ion pairing, where the electron transfer is favored by preorientation and a short distance between the electron donor and the acceptor previous to excitation of ArN2⊖ by light.
    Additional Material: 5 Ill.
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