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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Geophysical prospecting 29 (1981), S. 0 
    ISSN: 1365-2478
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Physics
    Notes: A forward solution for the reflection response of a parallel stratified lossless medium characterized by discrete reflection coefficients and unequal layer delays, for a normally incident pressure source signal, is presented. The notation, which details the reflection history of each wavelet in a response record, facilitates systematic enumeration of all terms in the reflection impulse response model, the determination of compact closed form expressions for amplitudes and delays of multiply reflected wavelets, and the aggregation of dynamic analog groups. An equal delay time constraint on layer thicknesses leads then to the reflection sequence or synthetic seismogram structure as an infinite sum of wavelets by their order of reflection.
    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
    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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  • 4
    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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  • 5
    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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  • 6
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 389 (1982), 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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  • 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 113 (1980), S. 941-954 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Statistical Syntheses of RotaxanesThe acetalisation of the 28-membered cyclic diols 11a, b with the long-chain dibromo ketone 12 gives acetals 13a, b. These compounds react with triphenylmethyllithium to give 17a, b and 18a, b from which the rotaxanes 20a, b are obtained in 0.066 or 0.18 and 0.12% yield, respectively, after hydrolysis of the acetal bonds. The reacetalisation of rotaxane 20b affords, by an intraannular reaction, the prerotaxane 18b in pure form.
    Notes: Die Acetalisierung der 28-gliedrigen cyclischen Diole 11a, b mit dem langkettigen Dibromketon 12 ergibt die Acetale 13a, b. Nach Umsetzung mit Triphenylmethyllithium zu 17a, b und 18a, b werden nach Hydrolyse der Acetalbindungen die Rotaxane 20a, b in Ausbeuten von 0.066 und 0.18 bzw. 0.12% als farblose Öle isoliert. Durch Reacetalisierung von 20b wird in einer intraannularen Reaktion das Prärotaxan 18b in reiner Form erhalten.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 65 (1982), S. 1038-1044 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 2-Pyridylhydrazones as Carbonyl Derivatives to induce Fragmentation in Mass SpectrometryIt was found that the 2-pyridylhydrazone is a derivative of the carbonyl group, which is able to induce fragmentation of an alicyclic skeleton with an efficiency comparable to that of the tertiary amino group and the ethylene acetal group.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 15 (1992), S. 300-312 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Thick-walled components subjected to pulsating internal pressure are widely applied in high-pressure technology and in manufacturing processes such as fluid-jet cutting and high-pressure cleaning, mainly in conjunction with reciprocating pumps. Corrosive fluids require high-strength and tough chrome-nickel steels with soft martensitic or semi-austenitic structure. This contribution reports on the fatigue of thick-walled plain and cross-bored pipes made from high alloy chrome-nickel steels such as X5 CrNiMoCu 21 8 and X5 CrNiMo 16 5. The speciments, uniaxial standard form and thick-walled pipes, were cut from forged blocks in the three axial directions. For loading with pulsating pressure, a suitable, high-frequency piston pulsation machine has been developed. The fatigue tests on pipe specimens show typical Woehler characteristics with only slight scatter and relatively good isotropy. The surprisingly large admissible pulsating pressure can be explained for the applied steels by dynamic generation of residual stresses as a result of shake-down effects. Presentation in a Smith digram explains the occuring dynamic shake-down and its favourable results in comparison to the more brittle highly tensile steels. It also reveals that heat treatment to higher tensile strength does not always yield an increase in the admissible pulsating pressure. It will be shown that static autofretting and shake-down affect the fatigue strength of thick-walled pipe specimens in the same way. Tests with internal liners in the tube specimens provide indications on the sensitivity of material failures towards fluids. The investigation aids the understanding of the fatigue behaviour and the design of components made of modern high-strength corrosion resistant steels.
    Additional Material: 20 Ill.
    Type of Medium: Electronic Resource
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