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  • 1
    Electronic Resource
    Electronic Resource
    Composition sterolique et morphogeneses reproductrices chez Gnomonia leptostyla
    Amsterdam : Elsevier
    Phytochemistry 18 (1979), S. 431-435 
    Details
    ISSN: 0031-9422
    Keywords: Ascomycetes ; Gnomonia leptostyla ; MIKE spectrometry. ; free sterols ; reproductive morphogenesis ; sterol esters: Δ^5^,^7 and Δ^5 sterols ; sterols
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/S0031-9422(00)81882-8
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  • 2
    Electronic Resource
    Electronic Resource
    Unimolecular chemistry of oxazole and isoxazole radical cations in the gas phase: Combined experimental and molecular orbital study (1992)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 27 (1992), S. 317-325 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Molecular radical cations of oxazole (1) and isoxazole (2) dissociate by losing carbon monoxide or a hydrogen atom, respectively. These fragmentations were examined by use of tandem mass spectrometry, flash vacuum pyrolysis and ab initiomolecular orbital calculations. A multi-step mechanism is proposed which incorporates these new experimental and theoretical data. The case of methylated homologues of 1 and 2 is also considered.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210270326
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  • 3
    Electronic Resource
    Electronic Resource
    The formation of cyclopentadienone ions. An internal oxidation process (1989)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 3 (1989), S. 320-322 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: 1-(2-nitrophenyl)benzotriazole loses nitrogen upon electron ionization. This reaction is followed by a Wolff-type ring contraction to give cyclopentadienylidene methanimine ions which undergo an internal oxidation process producing ionized cyclopentadienone.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290030913
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  • 4
    Electronic Resource
    Electronic Resource
    Fragmentation D'azoles Sous L'impact Electronique. VVoir Réf. 1. - Isomerisation Du Benzimidazole Avant Degradation (1974)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 9 (1974), S. 1188-1193 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The mass spectrum of benzimidazole is investigated using deuterium and carbon-13 labelling. The [M - HCN]+· ion is the result of two competitive reaction. Isomerisation into a cyanoaniline structure which eliminates HCN from the amino group and also from the nitrile group (by an ortho effect) is confirmed by ions abundance ratios. Hydrogen scrambling does not occur to a significant extent in the ions under consideration.
    Notes: Le spectre de masse du benzimidazole est étudié à l'aide de marquages isotopiques (D et 13C). Après lyionisation il se produit une isomérisation en o-cyanoaniline, à partir de laquelle deux réactions compétitives conduisent à l'ion [M-HCN]+·. La perte de HCN au niveau de la fonction amino et, par effect ortho, au niveau de la fonction nitrile est confirmée par des mesures d'abondances ioniques. On n'observe pas de réarrangements statistiques d'hydrogènes avant l'élimination de HCN.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210091206
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  • 5
    Electronic Resource
    Electronic Resource
    Fragmentation d'azoles sous l'impact electronique VI-indazole (1975)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 10 (1975), S. 558-560 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Molecular ion isomerisation precedes the fragmentation of indazole upon electron-impact.
    Notes: Une ismérisation des ions molécularies précéde la fragmentation de l'indazole sous l'impact.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210100711
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  • 6
    Electronic Resource
    Electronic Resource
    Fragmentation d'azoles sous l'impact electronique. X - etude de rearrangements cycliques en serie alkylamino-1,2,4-triazole (1975)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 10 (1975), S. 946-957 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: In situ generation of the individual tautomers by fragmentation reactions in the mass spectrometer is shown to provide a means of studying rearrangements of the type involved in prototropic equilibria. C-aminotriazole was generated in different tautomeric forms by ethylene elimination from the N-ethyl compounds and the tautomers were shown to equilibrate prior to further fragmentation. Ethylene elimination was shown by characterising the energy partitioning associated with the metastable ion reactions to occur via a four centred transition state from two ethylamino-triazole isomers and via a five centred transition state from the third. These mechanistic conclusions were supported by characterising frequency factors through measurements of kinetic isotope effects. Propene elimination from the corresponding propylaminotriazoles was studied by analogous methods. Energy partitioning and kinetic isotope effect studies were in agreement with a stepwise elimination of propene, or with a five centred β-hydrogen transfer mechanism.
    Notes: La formation in situ de tautomères individuels par des réactions de fragmentation dans le spectromètre de masse constitue une méthode de réarrangements tels que les équilibres prototropiques. Le C-aminotriazole est généré en ses différentes formes tautomères par élimination d'éthylène à partir des composés N-éthylés et ces tautomères sont isomérisés en une structure commune avant fragmentation. L'élimination d'éthylène se déroule via un état de transition à quatre centres pour deux éthylaminotriazoles isomères et via un état de transition à cinq centres pour le troisième comme le montrent les termes de partition d'énergie associés aux réactions aux réactions d'ions métastables. Ces conclusions mécanistiques sont étayées par l'étude d'effects isotopiques (méthode de caractérisation de facteurs de fréquence). L'élimination de propène à partir de propylaminotriazoles est abordée par des méthodes analogues. Les termes de partition d'énergie et l'étude d'effets isotopiques primaires sont en accord avec une élimination non concertée de propène ou avec un mécanisme de transfert de l'hydrogène β via un complexe transitoire à cinq centres.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210101105
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  • 7
    Electronic Resource
    Electronic Resource
    Profil de Pics Métastables (Pertes de NO·) en Série Nitroindazolique (1979)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 14 (1979), S. 114-116 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The kinetic energy releases associated with the loss of NO⋅ from nitroindazole molecular ions have been measured. The results show that, although the mass spectra are nearly identical, the corresponding metastable peak shapes can be used to differentiate the five isomers.
    Notes: Les libérations d'énergie cinétique associées aux fragmentations (pertes de NO·) des ions moléculaires de nitroindazoles ont été mesurées. Les résultats montrent que le profil des pics métastables correspondants permettent de différencier les cinq isomères.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210140211
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  • 8
    Electronic Resource
    Electronic Resource
    Letters to the editor (1982)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 17 (1982), S. 643-645 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210171211
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  • 9
    Electronic Resource
    Electronic Resource
    Basicity of azoles. 5 - Experimental gas phase basicities determined by mass spectrometry towards ab initio calculated protonation energies (1984)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 19 (1984), S. 627-630 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Using Cooks' method, the relative gas phase proton affinities of six azoles (imidazole, benzimidazole, pyrazole, indazole, 1-methylindazole and 2-methylindazole) have been determined. Ab initio calculations have been carried out for these six molecules and the corresponding cations, thus allowing the determination of protonation energies. Even the correlation between these quantities (-log K = 0.438+0.0744δΔEp) is far from perfect (r2 = 0.863), the order of basicity is the same. Aqueous basicities, pKa values, are totally uncorrelated.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210191208
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  • 10
    Electronic Resource
    Electronic Resource
    Applications of charge stripping/charge exchange spectra of organic ions (1985)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 20 (1985), S. 546-555 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The application of a new technique which involves the combination of charge stripping and charge exchange processes has been investigated. Ions are charge-stripped in the second field-free region of a triple-sector mass spectrometer (BEE geometry), and then subjected to a charge exchange reaction in the third field-free region. The resulting charge stripping/charge exchange (CS/CE) spectrum is free from interference, which is otherwise common in charge stripping spectra. Comparisons between charge stripping and CS/CE spectra are made in cases where both kinds of spectra are obtainable. In order to assess the applicability of this new technique to studies of isomeric ion structures, species for which charge stripping spectra have previously been unobtainable have been chosen. CS/CE spectra of [C6H6]+·, [C6H5]+, [C8H10]+· and [C7H7O]+ ions from a variety of precursors are recorded: in most cases, sufficient differences are observed to permit distinction between isomeric structures (or mixtures of structures). Previous studies which have shown that stable doubly charged molecular ions of ethane cannot be formed by the charge stripping technique are confirmed from its CS/CE spectrum.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210200904
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