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  • 1
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Phytochemistry 28 (1989), S. 2711-2716 
    ISSN: 0031-9422
    Keywords: Ferula communis var. brevifolia ; Umbelliferae ; daucane esters. ; sesquiterpenoids
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Phytochemistry 36 (1994), S. 1079-1080 
    ISSN: 0031-9422
    Keywords: Ferula communis var. genuina ; Umbelliferae ; farnesylacetophenone. ; roots
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Phytochemistry 26 (1987), S. 1613-1615 
    ISSN: 0031-9422
    Keywords: 4-hydroxycoumarin derivatives ; Ferula communis var. genuina ; Umbelliferae ; ferulenol ; ω-hydroxyferulenol.
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 0886-9383
    Keywords: Derivatization reaction ; Factorial design ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A number of nucleophiles have been successfully identified and quantified using the Kröhnke reaction with 2,3-diphenyl derivatives of quinolizinium salts. Optimization of the reaction conditions by means of a mathematical model involving analysis of the response surface has led to a better understanding of the factors exerting an influence on the above reaction.The parameters chosen were temperature, reaction time, base concentration, water concentration and nucleophile concentration. The reaction was developed in polar aprotic solvents (acetone, acetonitrile). To facilitate the nucleophilic attack, the presence of an organic base (triethylamine) was necessary, although concentrations in excess of 0·15M did not alter the development of the reaction. Since pharmaceutical solutions are often aqueous, the influence of water on the reaction was studied. Low water volumes have no significant influence on the opening of the quinolizinium ring by the nucleophilic reagent. However, when the water proportion exceeded that of the organic solvent, the fluorescence intensity was lower than expected. Development of the fluorescent reaction product was first detected 5 min after the reaction started. The fluorescence intensity reached its optimum value after 138 min.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Equilibration of hydrogen gas with the water in a variety of biological sample materials was carried out in Vacutainers using platinum-on-alumina catalyst physically isolated from the liquid water. The equilibration takes 3 days at room temperature - much slower than with catalysts which float on the water surface - but this reduces the short-term temperature sensitivity of the procedure, and the inexpensive materials used allow convenient disposal of biologically contaminated samples after analysis. The slow equilibration also allows time for complete exchange with water contained in a complex sample matrix such as plant stems or soil without the need for prior isolation of the water sample. The method has particular application in studies of human total body water where repeated studies can be carried out over a short time period without the need to wait for the previous dose to wash out. Water turnover rates from total diurnal energy expenditure studies measured by this method were not significantly different from those obtained by the zinc reduction method.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 13 (1986), S. 535-540 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Metabolic profiling of urinary organic acids from patients with juvenile-onset (Type 1) diabetes mellitus have revealed significantly elevated levels of 2-hydroxybutyric acids. To test the hypothesis that these metabolites, as well as 4-deoxyerythronic acid, are derived from L-threonine, stable isotope-labeled threonine was infused into an insulin-deficient dog and the incorporation of 13C into these metabolites was monitored by gas chromatography/mass spectrometry. Electron ionization was relatively insensitive, but positive chemical ionization with ammonia as the reactant gas gave both protonated molecules and [M+NH4]+ ions, which could be analysed by selected ion monitoring. The isotope-labeled species of 2-hydroxybutyric, 4-deoxyerythronic and 4-deoxythreonic acids were observed, but 13C was not incorporated into other organic acids. Thus, it is proposed that L-threonine is a precursor of these metabolites.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 7 (1975), S. 315-319 
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: In order to define the influence of an allenic type conjugation, the NMR spectra of vinylallene and of some of its methyl derivatives are analysed The signs of the coupling constants are also determined. These compounds are characterised by a planar s-trans structure of the two noncumulated double bonds. A discussion of the parameters, and especially of the methyl replacement effects, evidences the importance of the π type contributions. The theoretical calculations of the coupling constants by the methods of finite perturbation CNDO and INDO corroborate this interpretation.
    Notes: Afin de préciser l'influence d'une conjugaison de type allénique les spectres RMN du vinylallène et de plusieurs de ses dérivés méthylés ont été analysés et les signes des constantes de couplage ont été déterminés. Ces composés présentent une structure s-trans plane des deux doubles liaisons non cumulées. Une discussion des paramètres et no amment de l'influence des substitutions méthylées fait ressortir une forte prédominance des contributions de type π. Cette interprétation est corroborée par les calculs théoriques des constantes de couplages, effectués par la méthode de perturbations finies CNDO et INDO.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: A total analysis of the NMR spectra of 6-deoxy-L-hexopyranoses in the α-configuration and of the corresponding β-anomers was carried out. The parameters obtained are characteristic of a 1C (L) chair conformation, having the anomeric substituent in an axial orientation for the methyl α-fuco-, α-rhamno- and α-chinovopyranosides and for the α-fuco- and α-rhamnopyranosyl chlorides. The structure is also of a 1C (L) chair type for the methyl β-fuco- and β-chinovopyranosides; the geometry is the same for the β-fuco- and β-rhamnopyranosyl chlorides despite the anomeric effect of a chlorine atom. However, the NMR parameters of the β-chinovopyranosyl chloride are not explicable on the basis of a chair conformation with an equatorial chlorine or a boat structure.
    Notes: Une analyse complète des spectres RMN de désoxy-6 L-hexopyrannoses de configuration α et des anomères β correspondants est réalisée. L'ensemble des paramètres obtenus confirme l'existence d'une structure chaise 1C (L) présentant une disposition axiale du substituant anomère dans le cas des α-fuco-, α-rhamno- et α-chinovopyrannosides de méthyle et des chlorures de α-fuco- et α-rhamnopyrannosyle. La structure reste de type chaise 1C (L) dans le cas des β-fuco- et β-chinovopyrannosides de méthyle. Il en est de même en dépit de I'effect anomère dû à I'atome de chlore, pour les chlorures de β-fuco-et β-rhamnopyrannosyle. Par contre les paramètres RMN du chlorure de β-chinovopyrannosyle ne semblent interprétables ni sur la base d'une géométrie chaise à chlore équatorial ni par une structure bateau.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 13 (1980), S. 396-402 
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Rotational barriers and 15N chemical shifts have been measured in a number of ureas and thioureas. As anticipated on the basis of the 15N shifts, several previously unobserved rotational barriers could be detected by using lanthanide reagents or a high field spectrometer. Nearly constant effects on both the rotational activation energy and the 15N shift are produced on going from ureas to the corresponding thioureas, and correlations are found between the ΔG
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 3 (1971), S. 661-677 
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Coupling constants of 35 substituted pyridines are discussed and related to the electronic properties of the substituents and to the mechanism of coupling. A calculation of J is performed using Pople and Santry's theory and mutual polarizabilities obtained by CNDO/2 or Hoffmann methods. The influence of bicentric integrals on the theoretical values of J is examined.
    Notes: Les constantes de couplages relatives à un ensemble de 35 pyridines substituées sont discutées en relation avec les propriétés électroniques des substituants et le mécanisme du couplage. Un calcul de J est réalisé, sur la base de la théorie de Pople, à l′aide des valeurs de polarisabilités mutuelles obtenues par la méthode CNDO/2 et la méthode d'Hoffmann. L'influence d′une inclusion des intégrales bicentriques est examinée.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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