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  • 1990-1994  (4)
  • 1975-1979  (4)
  • Analytical Chemistry and Spectroscopy  (6)
  • (D-)ribose  (1)
  • Glucose  (1)
  • Kindliche Hörstörungen
  • Polymer and Materials Science
  • gyrotron
  • millimeter-wave
Material
Years
Year
Keywords
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Journal of molecular medicine 69 (1991), S. 31-36 
    ISSN: 1432-1440
    Keywords: (D-)ribose ; Glucose ; Insulin ; C-peptide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary D-ribose was given orally and/or intravenously to nine healthy subjects at doses ranging from 83.3 to 222.2 mg/kg per hour for at least four hours. The serum ribose level increased in a dose-dependent manner to maximum concentrations of 75 to 85 mg/dl. The serum glucose level decreased after the beginning of continuous ribose administration and was reduced as long as ribose was being administered. The oral or intravenous administration of 166.7 mg/kg per hour of ribose resulted in a 25% decrease in serum glucose. Higher intravenous doses of ribose did not provoke a further decrease in serum glucose concentration. Oral administration of 166.7 mg/kg per hour led to an increase in serum insulin concentrations from a mean of 8.4 (range 6.4–11.5) to 10.4 (range 6.3–15.4) μU/ml (p〈0.05). In contrast, intravenous administration did not change serum insulin concentrations significantly. The serum c-peptide concentration remained unchanged regardless of treatment. We conclude that the variations in plasma insulin concentrations do not account for the observed decrease in mean serum glucose concentrations accompanying D-ribose administration.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 28 (1993), S. 185-192 
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The gas-phase reactions of propene and cyclopropane radical cations with neutral ethylene were investigated by using Fourier transform, chemical ionization and tandem mass spectrometries. Both reactions form covalent C5H10 adduct ions. The adduct ions are hypothesized to form initially as distonic radical cations that isomerize via a substituted cyclopropane intermediate and are detected as the most stable C5H10 isomer, the 2-methylbut-2-ene radical cation. The rate constant for each reaction is approximately 20% of the theoretical collision rate, indicating that product ions are formed in one out of every five collisions of the C3H6 radical cations with neutral C2H4.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Electroanalysis 4 (1992), S. 19-26 
    ISSN: 1040-0397
    Keywords: Amalgam electrode ; cadmium ; macrocyclic complexes ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The electrochemical oxidation of cadmium amalgam was studied in the nonaqueous solvents CH2Cl2, 1,2-C2H4Cl2 and propylene carbonate. Significant coordination effects were observed between the electrogenerated Cd(II) ions and 18-membered macromonocyclic ligands, each containing six Lewis bases heteroatoms: 18-O6, 18-S6, 18-N2O4, and 18-N6. The stoichiometries and the stabilities of the resulting complexes were determined. These stabilities increase from 18-O6 or 18-S6 to 18-N6.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 14 (1979), S. 474-481 
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: New experimental data on the rearrangement reaction of various phenoxyethyl halides to give [C6H6O]+· are presented and compared with previous studies so that a coherent picture of this process can be developed. By examining the metastable kinetic energy release for low energy decomposing molecular ions of the phenoxyethyl halides, it has been concluded that formation of [C6H6O] occurs by competitive 1,2 and 1,3 hydrogen shifts from the alkyl carbons to oxygen followed by a rate determining C—O bond cleavage. This is substantiated by the absence of a primary hydrogen isotope effect. For more highly activated molecular ions, a new mechanism comes into play as evidenced by the appearance of a small hydrogen isotope effect. It is postulated that this third mechanism involves transfer of the alkyl hydrogen to the ortho position of the ring by a rate determining 1,5 shift, followed by a 1,3 hydrogen shift from the ortho methylene group to oxygen and rapid C—O bond cleavage. This 1,3 hydrogen shift to oxygen appears to be ‘catalysed’ by the halogen atoms yielding phenol ions. No indications have been found for the formation of tautomeric 2,4-cyclohexadienone ions. Furthermore, highly activated molecular ions produce [C6H6O]+· which can undergo metastable decomposition to lose carbon monoxide. Kinetic energy release measurements for the latter reaction show that the majority of these [C6H6O]+·ions have been formed as phenol ions as well. These arguments are supported by energetic measurements and by comparisons with previous ion cyclotron resonance and collisional activation studies.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 12 (1977), S. 55-62 
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In order to provide a comparison with the extensive research on the mechanism for elimination of water from various cyclohexanols, the mass spectra of 1-tetralol(1,2,3,4,-tetrahydro-1-naphthalenol) and 2-tetralol(1,2,3,4-tetrahydro-2-naphthalenol) have been investigated. Deuterium labeling experiments show that the 1-tetralol molecular ion expels water by a highly specific 1,4 elimination, whereas 2-tetralol undergoes a 1,3 elimination. Both of these processes are competitive with cycloreversion reactions. The ionization potentials and appearance potentials for the major fragments \documentclass{article}\pagestyle{empty}\begin{document}$ \left[{{\rm M - H}_{\rm 2} {\rm O}} \right]_{}^{_.^ + } $\end{document} and the cycloreversion products hae been measured using the Electron Distribution Difference method. In addition, the kinetic energy release in the metastable decompositions to lose water have been measured. It has been found that the 1,4 elimination for 1-tetralol releases over 50% of the available energy in the transition state, which is unexpected in view of the 6-membering ring transition state involved. This research also includes an investigation of the nature of the various \documentclass{article}\pagestyle{empty}\begin{document}$ \left[{{\rm C}_{{\rm 10}} {\rm H}_{{\rm 10}} } \right]_{}^{_.^ + } $\end{document} ions formed in the rearrangement reaction to lose water.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 12 (1977), S. 258-260 
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A broad range of kinetic energy release has been found for the 1,4 elimination of water in a series of ortho substituted benzyl alcohols and benzoic acids. It is suggested that the trend reflects, in part, the position of the activated complex on the reaction coordinate. More specifically, reactions which proceed via an ‘early’ transition state release only small quantities of energy, whereas those processes occurring ‘later’ release a larger fraction of the available energy. Consequently, the o- methyl derivatives give large kinetic energy release compared to o- amino or hydroxy substituted compounds. Father verification is obtained from the small kinetic energy release observed for the 1,4 ionic dehydration in simple,acyclic alcohols.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 28 (1993), S. 1184-1188 
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Protonated 4,5-diacetoxyphenanthrene and 2,2′-diacetoxybiphenyl dissociate, owing to the interaction of the two acetoxy groups, by eliminating a molecule of acetic acid. This novel proximity effect, which occurs for a fast atom bombardment-produced closed-shell ion, was examined in detail using tandem mass spectrometric methods. This process, which was first observed in the decompositions of acetylated complex natural products such as stentorin and hypericin, may serve as a general process for determining the proximity of hydroxyl groups in polycyclic aromatic compounds.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 6 (1979), S. 356-358 
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Vaporization of a ornithine-containing polar lipid from Thiobacillus thiooxidans has been accomplished by thermolysis in a chemical ionization source. The thermolysis has been shown to be more extensive than previously thought. It occurs in at least two steps, the first being dehydration of the ornithine to produce a substituted piperidone. This fragment undergoes a facile elimination to produce two neutral lipid components: a long chain fatty acid and piperidone-containing fatty amide. The results demonstrate the utility of chemical ionization for developing an understanding of a thermolysis process.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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