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  • Articles: DFG German National Licenses  (709)
  • 1980-1984
  • 1975-1979  (709)
  • 1976  (709)
  • Analytical Chemistry and Spectroscopy  (566)
  • Engineering General  (143)
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  • Articles: DFG German National Licenses  (709)
Material
Years
  • 1980-1984
  • 1975-1979  (709)
Year
  • 1
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 3 (1976) 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 3 (1976), S. 1-3 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The detection of a small amount of 13C labelled methyl benzoate and its metabolites in human urine dosed 13C labelled aspirin was carried out by a new mass fragmentographic technique.
    Additional Material: 4 Ill.
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  • 3
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 3 (1976), S. 4-13 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The mass spectroscopic behaviour of the methyl ester of prostaglandins E1 and E2 has been studied with the aid of low eV spectra, measurements on metastable ion decompositions and high resolution mass measurements. Mechanisms are proposed for the formation of the majority of the abundant fragment ions of these biologically important compounds. The mass spectra of free acids are also discussed.
    Additional Material: 2 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 3 (1976), S. 21-27 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The biological implications, the reaction possibilities and the structure of different derivatives of N-hydroxy-2-fluorenylacetamide have been described.
    Additional Material: 5 Ill.
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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: The amino acid sequence of a polypeptide can be deduced by an identification of all the dipeptides obtained from a Dipeptidylaminopeptidase I hydrolysate of the original polypeptide and its des N-terminal amino acid derivative. The components of such dipeptide mixtures can be readily identified from the chemical ionization (helium) mass spectra of their N-ethoxycarbonylpropenyl methyl ester derivatives without prior separation. The pyrolytic conversion of N-protected peptide dimethyltrideuteromethyl anilinium salts to their methyl esters in the direct insertion probe of a mass spectrometer was found to be most suitable for the derivatization of such dipeptide mixtures.
    Additional Material: 9 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 3 (1976), S. 48-49 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A selective ion monitor for the Perkin-Elmer Model 270 gas chromatograph mass spectrometer is described.
    Additional Material: 2 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 3 (1976), S. 50-50 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 3 (1976) 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The mass spectral characterization of nine kinds of estrogen glucuronides was investigated. The glucuronides were analysed after conversion to n-propyl ester-O-TMS ether derivatives by gas chromatography mass spectrometry. The fragmentation of these derivatives is discussed using deuterium labels and TMS-d9 imidazole. A clear-cut difference was found between aliphatic and aromatic glucuronic acid conjugates. In particular the [M - 362]+· fragment ion was characteristic in the mass spectra of estrogen 3-glucuronides. On the other hand, four isomers of estriol and 16-epiestriol glucuronides containing an aliphatic acetal linkage were also characterized by the fragment ions of mle value 204, 345, 415 and 431 and their relative intensities. Thus, all nine estrogen glucuronides were discriminated mass spectrometrically.
    Additional Material: 7 Ill.
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  • 10
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The mass spectra of the dimethylphosphinic, dimethylthiophosphinic and dimethylphosphinous ester derivatives of several monohydroxy steroids are reported. The fragmentations of the derivatized steroids largely depend on the nature of the the phosphorus-containing ester group. Phenolic ester derivatives exhibit the base peak at the molecular ion, whereas the spectra of the secondary phosphinic esters are dominated by very intense protonated phosphinic acid ions [Me2 P(XH)(OH)]+ at m/e 95 (X = O) or at m/e 111 (X = S). The present results also indicate the low ionization potential for the phosphinic ester group. Due to their good gas chromatographic properties, these steroid derivatives appear to be particularly suitable for gas chromatographic mass spectrometric analysis of biochemical materials.
    Additional Material: 4 Ill.
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  • 11
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Excellent resolution and subsequent identification of free organic acids extracted from mixed, unstimulated human saliva was obtained by gas chromatography using high resolution open tubular glass capillary columns coupled with mass spectrometry computer instrumentation. In addition to the organic acids, identified as their trimethylsilyl derivatives, the presence of 2,6-di-t-butylcresol - a food preservative - and cholesterol was established by mass spectrometry. The effects of aspirin ingestion as well as diurnal variation were studied to demonstrate the possible clinical significance of this noninvasive approach to metabolic profiling.
    Additional Material: 2 Ill.
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  • 12
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 3 (1976), S. v 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 13
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The sterol compositions of three oceanic jellyfish have been determined using gas chromatographic mass spectrometric techniques involving the use of two separate gas chromatographic column systems. The components in overlapping peaks have been identified by comparison of the mass spectra of peaks in the two column systems using subtractive techniques. A mid-water animal, Periphylla periphylla, was found to contain a very complex and unusual sterol profile including rare 5α-stanols, whereas two other oceanic jellyfish Pelagia noctiluca and Atolla wyvillei contained similar mixtures of Δ5 sterols to those previously isolated from coastal species.
    Additional Material: 3 Ill.
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  • 14
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 3 (1976), S. 28-31 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A general derivatization method has been developed for both primary and secondary aminoalkylphosphonic acids. Derivatization is effected by reaction with trifluoroacetic acid and trifluoroacetic acid anhydride followed by esterification using ethereal diazo-n-butane. This method can be used for microgram quantities and permits ready characterization by both gas chromatography and gas chromatography mass spectrometry. The structure of this derivative has been verified by mass spectrometry and proton magnetic resonance. Fragmentation patterns were confirmed by high resolution mass spectrometry, isotope labeling and the formation of derivative analogs.
    Additional Material: 5 Ill.
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  • 15
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 3 (1976), S. 45-47 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The measurement of diphenoxylic acid, the major metabolite of diphenoxylate, has been performed in man using a deuterium labelled internal standard and multiple ion monitoring using a gas chromatograph mass spectrometer. The determination of plasma concentrations following administration of diphenoxylate to man is described.
    Additional Material: 4 Ill.
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  • 16
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The methyl ester of trifluoroacetic acid was prepared by reaction with N,N′-dimethylformamide dimethylacetal and was successfully passed through a gas chromatograph. Trifluoroacetic acid was detected by the use of gas chromatography and low and high resolution gas chromatography mass spectrometry in an acidic extract of an incubation medium containing microsomes, reduced nicotinamide adenine dinucleotide phosphate, oxygen and halothane. However, trifluoroacetic acid could not be detected when nicotinamide adenine dinucleotide or oxygen was omitted from the incubation system. From these results, it was proved that halothane is oxidatively metabolized to trifluoroacetic acid by hepatic microsomes.
    Additional Material: 4 Ill.
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  • 17
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 3 (1976), S. v 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 18
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 3 (1976), S. v 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 19
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A gas chromatographic mass spectrometric method has been developed for the rapid determination of a urinary tetrasaccharide (α-D-Glc-(1 → 6)-α-D-Glc-(1 → 4)-α-D-Glc-(1 → 4)-D-Glc). The urine sample is first fractionated by gel chromatography. An appropriate internal standard is added to the pooled tri-pentasaccharide fraction. Which is then reduced, methylated and fractionated by g.c. The identification of the tetrasaccharide derivative is based on the g.c. relative retention time and the mass spectrum of the reduced permethylated tetrasccharide derivative is based on the g.c. relative retention time and the mass spectrum of the reduced permethylated tetrasaccharide. The normal excretion rate was in the range of 0.1-2.5 mg per 24 hours. Greatly increased amounts (9.4-89.6 mg 24 h-1) were found in the urine of patients with glycogen storage disease type II and type III and in one patient with unclassified muscular disease. A moderate increase (3.6-8.6 mg 24 h-1) was observed in one patient with glycogen storage disease type VI. in two patients with Duchenne muscular dystrophy and in two other patients with unclassified muscular disease.
    Additional Material: 4 Ill.
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  • 20
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Phenacetin, paracetamol and acetanilide can be determined in a plasma or urine sample by the use of deuterium labelled analogues. These are produced by reaction of hexadeuterioacetic anhydride with the appropriate aromatic amine. The -NHCOCD3 group is stable to hydrogen exchange below pH 8. The internal standard is added to the plasma or urine after enzymatic hydrolysis of the paracetamol conjugates and an ethyl acetate extract at pH 5 is evaporated under nitrogen and the residue derivatized with N, O-bis-(trimethylsilyl)-acetamide. An aliquot of this solution is injected into a g.c.m.s. system, and one ion characteristic of the material under study and the ion from the deuterium analogue (3 mass units greater) are monitored using a voltage switching technique. In the case of phenacetin, for example, ions at 251 and 254 are monitored. Calibration curves relating different weight ratios of the hydrogen and deuterium compounds to their respective signals from the gas chromatograph mass spectrometer are used to calculate the amount of a compound in a particular sample. These methods have been developed to study the oxidation of acetanilide to paracetamol and the de-ethylation of phenacetin to paracetamol. Preliminary results from experiments with phenacetin will be discussed.
    Additional Material: 3 Ill.
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  • 21
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 3 (1976), S. v 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 22
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 3 (1976), S. 196-200 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Organic vapors in ambient air, at or near an industrial site in Baltimore, Maryland, were collected by adsorption on a sorbent of porous polymer (Tenax GC, 35/60). The pollutants were recovered by thermal desorption and analyzed by gas-liquid chromatography mass spectrometry computer using capillary glass SCOT columns. N-Nitrosodimethylamine was identified from its mass spectrum as a constituent of the atmosphere in the areas sampled. The identification of this compound was confirmed by comparison of its mass spectrum with that of authentic N-nitrosodimethylamine; identical retention times of unknown and authentic compound on three different capillary columns were observed.
    Additional Material: 6 Ill.
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  • 23
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 3 (1976), S. 207-211 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A selected ion monitoring assay has been developed to measure plasma levels of the bronchodilator pirbuterol in animals and man. Pirbuterol is extracted from plasma with acetone + potassium carbonate and after further purification is converted to its trimethylacetyl derivative. With the use of the stable isotope labeled internal standard, pirbuterol-d9, precisions of 10% and 6% were achieved at plasma concentrations of 1 and 20 ng ml-1, respectively. The synthesis of the deuterium labeled internal standard is described.
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  • 24
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A quantitative mass fragmentographic method for the simultaneous determination of labeled and unlabeled propoxyphene in plasma is described. Dogs treated daily with propoxyphene-d0 were treated with a pulse dose of propoxyphene-d2 at day 20. It was found that following an initial rapid equilibrium phase levels of propoxyphene-d2 fell more rapidly than those of propoxyphene-d0. This result suggests that ‘deep’ pools of tissue bound propoxyphene exist which exchange very slowly with drug present in the central compartment. Experimental evidence is presented which demonstrates that the difference in behavior of propoxyphene-d0 and -d2 is not due to unanticipated secondary isotope effects.
    Additional Material: 5 Ill.
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  • 25
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 3 (1976), S. 226-229 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Urine from rats and sheep given single oral doses of [14C]propachlor contained 14C metabolites in which the chlorine of propachlor was replaced by a methylsulfonyl group. Methylsulfonyl-containing metabolites were also isolated from the urine of rats given an intraperitoneal dose of the cysteine conjugate of [14C]propachlor; this indicated that the methylsulfonyl-containing metabolites resulted from metabolic reactions subsequent to the mercapturic acid pathway.
    Additional Material: 1 Ill.
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  • 26
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The methane chemical ionization spectra of a number of tertiary and quaternary amines with a N-trideuteromethyl group show substitution of this group by methyl. The isotopic purity of the original amines was shown to be 〉 99% using ammonia as a reagent gas.
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  • 27
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Catabolic intermediates of sodium dipropylacetate, an anticonvulsant drug, in the urine extracts of the drug-treated rats were examined by the aid of gas chromatography mass spectrometry. Eleven drug-specific peaks were estimated as unmetabolized sodium dipropylacetate, succinic acid, 2-n-propyl-3-hydroxypentanoic acid, 2-n-propyl-4-hydroxypentanoic acid, 2-n-propyl-3-oxopentanoic acid, 2-n-propyl-5-hydroxypentanoic acid, adipic acid, 2-n-propylglutaric acid, dipropylacetic acid glucuronide, propionic acid and 3-heptanone. Administration of sodium dipropylacetate with isoleucine to rats resulted in the disappearance of 2-n-propyl-3-oxopentanoic acid and a considerable decrease in 2-n-propyl-3-hydroxypentanoic acid. These data indicated that β-oxidation was involved in the metabolism of sodium dipropylacetate as well as glucuronide conjugation and ω-oxidation.
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  • 28
    Electronic Resource
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    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 3 (1976), S. v 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 29
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A sensitive method for the qualitative and semiquantitative determination of terbutaline in plasma and urine has been developed After a single oral dose of 5 mg terbutaline sulphate the drug could be analysed easily. The detection limit in plasma is less than 1 ng ml-1.
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  • 30
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reductive methylation (the Eschweiler-Clarke reaction) was used as a route for the synthesis of differently deuterium labelled variants of trimethylamine with the ultimate aim of preparing labelled variants of choline and acetylcholine. Combinations of unlabelled and labelled formaldehyde and formic acid yielded symmetrically labelled trimethylamines of high isotopic purity. The labelled congerers to acetylcholine and choline that were prepared subsequently provide suitable internal standards and tracers to be used in mass spectral analysis and in the evaluation of the pharmacokinetics of the parent compounds.
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  • 31
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    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 3 (1976), S. 272-277 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Using electron impact and field desorption mass spectrometry, structures are proposed for narasin and a related ionophore, A28086B, derived from fermentation. The ionic fragmentation of these compounds and their derivatives is discussed and compared with that of salinomycin, whose structure has been determined by X-ray diffraction.
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  • 32
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A sensitive method for the simultaneous determination of bufuralol and its pharmacologically active metabolites in human plasma is described. The O-trimethylsilyl,N-trifluoroacetyl derivatives are assayed by mass fragmentography. Sensitivity is 1 ng ml-1 plasma for bufuralol and about 250 pg ml-1 for the metabolites. An alternative procedure which uses gas chromatography with electron capture detection is also described. The sensitivity of this is about 10 ng ml-1 plasma for all drug-related components.
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  • 33
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    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 3 (1976) 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 34
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A low resolution, high sensitivity study has been made of the field desorption mass spectrum of glucagon, a 29 amino acid residue underivatized peptide. The highest molecular weight fragments observed, when spectra were taken under conditions which minimized surface reactions of the peptide on the emitter, were found to contain no more than 18 amino acid residues. The most probable fragmentation processes for ions larger than m/e 600 were the production of fragments containing 10, 11 or 12 amino acid residues.
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  • 35
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    Biological Mass Spectrometry 3 (1976), S. 217-225 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Through the combined use of stable isotope labeling and gas chromatographic mass spectrometric analysis, the metabolic patterns for propoxyphene have been determined in laboratory animals and man. The rat and dog eliminated propoxyphene and its metabolites principally via the bile, while the rabbit more closely resembled man in excreting the metabolic products into urine. Metabolites in rat and rabbit existed as conjugates, whereas in dog and man the metabolites were excreted as a mixture of the free and unconjugated forms. The primary route of metabolism in all species studied was N-demethylation. However, the rat and rabbit extensively hydroxylated propoxyphene and its metabolltes prior to elimination. Metabolites arising from ester hydrolysis were found in rat and man. N-acetylated products were identified in all four species. A metabolite formed from cyclization and dehydration of dinorpropoxyphene was isolated in urine and was further identified as a circulating metabolite in dog plasma.
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  • 36
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    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 3 (1976), S. 232-234 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Gentamicin sulphate employed in therapeutics consists of a mixture of three major aminoglycoside components, the gentamicins C1, C1a and C2. In the electron impact mass spectra of these components weak parent ions may be observed but they are of no diagnostic value in the commercial mixture. Chemical ionization and field desorption spectra of individual gentamicin components and commercial mixtures are reported and discussed. Isobutane chemical ionization spectra exhibit some fragmentation, but under optimum field desorption conditions little glycosidic cleavage is observed and [M + H]+ ions dominate the spectra.
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  • 37
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    Biological Mass Spectrometry 3 (1976), S. 295-298 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The concentration of oestrone, oestradiol and progesterone in ovarian tissue have been determined directly by quant tative high resolution mass fragmentography without the necessity of extraction or purification. The changes in the levels of these steroids in the ovary throughout a 28 day period correlate well with those measured in plasma and also with those of the corresponding metabolites excreted in urine. Some benign ovarian tumours (cysts) have been shown to contain abnormally large amounts of progesterone.
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  • 38
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    Biological Mass Spectrometry 3 (1976), S. 166-171 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The mass spectra of peracetylated daunorubicin, N-octanoyl-, N-dodecanoyl- and N-(N'-dodecanoylglycyl)daunorubicin, and perdeuteroacetylated N-dodecanoyldaunorubicin were analyzed. Major fragmentation pathways were suggested and ion compositions were determined by high resolution measurements.
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  • 39
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Field desorption mass spectra have been obtained for dipalmitoylphosphatidyl choline-d0, -d4 and -d9. The two latter compounds were synthesized from dimethylene-d4 choline bromide and trimethyl-d9 choline bromide, respectively. Comparison was made of spectra of these three compounds obtained at different field anode temperatures in order to establish the composition of the major cleavage, rearrangement, and association ions. At low anode heating currents (≤ 20 mA) the most intense peak is [M + 1]+ which accounts for c. one-third of the total ionization. At higher temperatures various fragmentation processes, some of which are without analogy in electron impact mass spectrometry, become more important. The presence of an intermolecular methyl transfer process has been confirmed.
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  • 40
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A gas chromatographic mass spectrometric method for the quantitative determination of imipramine and its N-demethylated metabolite desipramine in plasma samples at the nanogram level is reported. The method involves derivatization of the extracted drugs with trifluoroacetylimidazole, a mild derivatizing reagent. Specificity is provided by selected ion recording of the [M + H]+ ions, formed upon chemical ionization with methane as reagent gas. Quantitation is achieved by stable isotope dilution techniques, using deuterium labeled analogs, prepared by acid-catalyzed exchange, as internal standards. Data on patient samples are presented.
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  • 41
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    Biological Mass Spectrometry 3 (1976), S. 316-328 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Phosphates and phosphoramidates related to 2-chloro-4-t-butylphenyl methyl methylphosphoramidate (crufomate) were synthesized to aid in the identification of crufomate metabolites. Deuterium labeling, metastable determinations and precise mass measurements were used to establish fragmentation pathways. Evidence was obtained for the rearrangement of an N-formyl phosphoramidate (the expected result of oxidative metabolism of N-methyl phosphoramidates) to an iminomethyl phosphate.
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  • 42
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    Biological Mass Spectrometry 3 (1976), S. 335-339 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Metabolites of the antitumor agent, ellipticine (NSC 71795), are mainly secreted in rat bile as two conjugates of hydroxylated ellipticine. The possible involvement of an arene oxide intermediate prior to hydroxylation and conjugation has been studied using 7,9-dideutero-ellipticine and by determining the conservation of deuterium in the phenolic products. The deuterated drug was synthesized by acid catalyzed exchange and was characterized by nuclear magnetic resonance and high and low resolution mass spectrometry. Mass spectra of two conjugated metabolites from rat bile showed a mass ion at m/e 263 (singly deuterated hydroxylated ellipticine). There was no evidence for conservation of deuterium at the position of hydroxylation (m/e 264). These results indicate that the major pathway of metabolism for this cancer chemotherapeutic drug, prior to conjugation and excretion in rat bile, proceeds by aromatic hydroxylation apparently without involving an arene oxide/NIH shift mechanism.
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  • 43
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    Biological Mass Spectrometry 3 (1976) 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 44
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Endogenous tryptamine, 5-hydroxytryptamine, indoleacetic acid, 5-hydroxyindoleacetic and tryptophan have been recovered from urine and cerebro-spinal fluid by adsorption on XAD-2 resin (0.3 g). After adsorption of the sample on the resin, desorption with methanol provides a single fraction that contains all of these metabolites. The mass spectra of their pentafluoropropionyl derivatives show prominent ions at m/e 276 and 438 which are characteristic of indoles and 5-hydroxyindoles, respectively, a feature that allows the concurrent determination of all the components of each group by functional group analysis. A method has been developed to carry out single ion monitoring with the peak matching system of an Hitachi RMU-6H mass spectrometer. Identifications are based on the respective Kovats Indices and single ion monitoring of two characteristic ions per compound: tryptophan (m/e 276 and 347); tryptamine (m/e 276 and 289); indoleacetic acid (m/e 276 and 335); 5-hydroxytryptamine (m/e 438 and 451); 5-hydroxyindoleacetic acid (m/e 438 and 497). The method described illustrates the feasibility of assaying biogenic indoleamines and acidic metabolites, as well as their precursor amino acid on a single fraction in contrast to other standard fractionation methods. This is possible even if the mass spectrometer is not equipped with an alternating voltage accelerator provided that it has a peak matcher, although the lack of an alternating voltage accelerator requires two separate injections of the same sample, for quantification and identification; one for the indole profile and another for the 5-hydroxyindole profile. Both profiles can be verified by individual monitoring of the other confirmatory ions. With this method the use of a multiple ion detector would allow a simultaneous determination of all of these metabolites in one gas chromatograph mass spectrometer run.
    Additional Material: 3 Ill.
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  • 45
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An improved method is described for measuring low levels of prostaglandin F2α in small volumes of cerebrospinal fluid. Single ion monitoring of the ion at m/e 423. derived from the methyl ester tri-TMS ether derivatives of prostaglandin F2α and the internal standard, ω-trinor-16-cyclohexyl prostaglandin F2α, is employed. Injection of 2 pg of prostaglandin F2α derivative gave a standard deviation of ±9%. The majority of patients had cerebrospinal fluid levels of up to 2 ng ml-1 of prostaglandin. F2α, whereas in certain neurological conditions with progressive disease, elevated levels were encountered, some of which were higher than 10 ng ml-1.
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  • 46
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    Biological Mass Spectrometry 3 (1976), S. 122-126 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Trimethylsilyl derivatives of 1-hexadecyl-2-decanoyl-, -hexadecanoyl- and -octadecenoylglycerols and 1-octadecyl-2-decanoyl-, -hexadecanoyl- and -octadecenoylglycerols as well as 1,2-dihexadecanoylglycerol were analysed by a gas chromatograph mass spectrometer system. The following points are characteristic of the fragmentation pattern of these 1-alkyl-2-acyl derivatives: (1) in the spectra of alkyl acyl derivatives, ions at [M - 15]+ and [M - 90]+· are 14 mass units less than those of the corresponding diacyl derivatives; (2) the base peak is m/e 130; (3) alkyl acyl derivatives show fragments due to one acyl group instead of the two acyl groups of diacyl derivatives; (4) ions at m/e 314 and 342, [R10 + 73]+·, are characteristic of the trimethylsilyl derivatives of hexadecyl- and octadecylglycerols, respectively; (5) the ion [M - R10]+ is present, but the complementary alkoxy ion is absent.
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  • 47
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    Biological Mass Spectrometry 3 (1976), S. 137-139 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Six major components of a mixture of the pyrolysis products of deoxyribonucleic acid have been analysed by combined low energy electron impact and collisional activation spectra. The method allowed the assignment of the structures of the different components in the complex mixture without prior separation.
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  • 48
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    Biological Mass Spectrometry 3 (1976), S. 146-148 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: α,α,β,β-d4-Serotonin (94% d4, 6% d3) has been synthesized for use as an internal standard in mass spectrometric determinations of serotonin in biological systems.
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  • 49
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    Biological Mass Spectrometry 3 (1976), S. 149-150 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 50
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Correlations between mass spectra and pharmacological activities were surveyed by means of computerized learning machine and cluster analysis. The principal component analysis and the nonlinear mapping techniques were used for the feature selection of the data set.
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  • 51
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    Biological Mass Spectrometry 3 (1976), S. 191-195 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The terminal amino group of amino acids and peptides is blocked as the N-succinyl derivative by reaction with succinic anhydride. The product is then converted to the N,O-permethyl derivative in order to increase its volatility for use in mass spectrometry. The permethylated N-succinyl derivative retains the advantages of the permethylated N-acetyl derivative in regard to ease of preparation on a small scale, volatility and the presence of characteristic fragmentation patterns in their mass spectra. However, peaks in the high mass region are more abundant due to loss of CH3O· from the N-succinyl carbomethoxyl group as well as from the C-terminal carbomethoxyl group. Ions characteristic of the sequence and of individual amino acids are observed, and molecular weight can be determined from the relatively abundant ion at [M — CH3O]+ and from the weak molecular ion.
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  • 52
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The use of the mass spectrometric integrated ion current technique for the quantitative analysis of some trace metals at their tetraphenylporphyrin chelates is described. The linearity of the calibration curves and the sensitivity of the technique are improved by employing deuterated tetraphenylporphyrin chelates as loading agents. Femtomole quantities of the chelates may be detected. The use of deuterated tetraphenylporphyrin chelates as internal standards overcomes the problems of losses occurring during chromatographic separation and by thermal decomposition in the mass spectrometer.
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  • 53
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    Biological Mass Spectrometry 3 (1976), S. 88-90 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Isomeric chlorinated biphenyls are observed to yield very similar mass spectra, rarely exhibiting a [M — Cl]+ fragment of any siVgnificant magnitude. However, those isomers containing three ortho chloro substituents display a relatively intense [M — Cl]+ fragment. A rationalization for this observation is put forth on the basis of the relative stabilities of both product and reactant.
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  • 54
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The metabolism of 5-(4′-chloro-n-butyl)picolinic acid, which inhibits dopamine β-hydroxylase and exhibits an antihypertensive effect, has been studied by gas chromatography mass spectrometry, utilising characteristic reaction products after derivatization. In rat urine five metabolites were identified by mass spectral analysis. It is found that four were elongated by a C2 unit in the carboxyl group at the 2-position on the pyridine ring and accounted for approximately 50% of the radioactivity in the 24 hour urine. The facts show that the metabolic pathway corresponding to the chain elongation of fatty acids is the major route of metabolism for this drug in the rat. Furthermore, this pathway would be confirmed in man, rabbit, guinea pig and mouse.
    Additional Material: 11 Ill.
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  • 55
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The electron impact and the hydrogen and methane chemical ionization mass spectra of 5,6-dihydro-2-methyl-1,4-oxathiin-3-carboxanilide, the sulfoxide and sulfone derived therefrom, and 2-(2-hydroxyethylthio)-acetoacetanilide enol have been determined. All four compounds show abundant molecular ions in the electron impact spectra and abundant [MH]+ ions in the methane chemical ionization spectra (along with the expected [M + C2H5]+ and [M + C3H5]+ ions), but relatively low [MH]+ ion signals in the hydrogen chemical ionization spectra. From high resolution mass measurements and metastable transitions determined by metastable ion refocusing, electron impact fragmentation mechanisms have been established. For 5,6-dihydro-2-methyl-1,4-oxathiin-3-carboxanilide, 5,6-dihydro-2-methyl-1,4-oxathiin-3-carboxanilide-4-oxide and 5,6-dihydro-2-methyl-1,4-oxathiin-3-carboxanilide-4,4-dioxide the major fragmentation mode involves loss of the anilino radical from [M]+, followed by loss of C2H4. Fragmentation to form the aniline molecular ion increases in importance with increasing oxidation state of the sulfur. In the chemical ionization of these three compounds fragmentation of [MH]+ proceeds in a similar fashion by loss of neutral aniline and by formation of protonated aniline. The electron impact mass spectrum of 2-(2-hydroxyethylthio)acetoacetanilide is dominated by the molecular ion and the aniline molecular ion. However, in the chemical ionization mass spectra characteristic fragment ions involving loss of water and loss of aniline from [MH]+, as well as protonated aniline, are observed and serve to characterize the compound.
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  • 56
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    Biological Mass Spectrometry 3 (1976) 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 57
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    Biological Mass Spectrometry 3 (1976), S. 261-264 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Polyunsaturated fatty acids of human serum were analysed by combination gas-liquid chromatography and chemical ionization mass spectrometry, using isobutane as the reagent gas. The method described yielded the molecular ion of long chain unsaturated fatty acids as the base peak; these were weak or unobservable in the corresponding electron impact mass spectra. In the chemical ionization mass spectromtery, the derivatization with trimethylsilyl ether was demonstrated to be useful for the location of the double bonds of unsaturated fatty acids. Applied to the serum polyunsaturated fatty acids, these methods have given identification of C18:4, C20:4, C20:5, C22:4, C22:5ω-6, C22:5ω-3, and C22:6.
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  • 58
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    Biological Mass Spectrometry 3 (1976), S. 278-280 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The electron impact fragmentation of 1, 2-O-isopropylidene-α-D-glycero-tetros-3-ulofuranose has been studied with the help of deuterium and 18O labelling. The effect of substituting a hydrogen atom of C-4 for a CH3· radical and that of replacing the carbonyl function with a cyanomethylenic substituent is also reported.
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  • 59
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    Biological Mass Spectrometry 3 (1976), S. 265-271 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The use of linear regression analysis for the reduction of isotope dilution data is reviewed. The calculation of linear regression statistics is based upon four assumptions: zero variance in the independent variable, equal variance for all values of the dependent variable, linearity and continuity. Unfortunately, isotope dilution data often violate one or more of these assumptions, which results in the calculation of an inaccurate calibration line. The inaccuracies can be avoided through careful inspection of the data, including analyses of variance and linearity. Large differences in the variances of the dependent variable require the use of a weighted linear regression. Nonlinearity necessitates either discarding data in the nonlinear portion of the calibration or the calculation and use of atom % excess and dilution instead of the simple isotope ratios.
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  • 60
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    Biological Mass Spectrometry 3 (1976), S. v 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 61
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    Biological Mass Spectrometry 3 (1976), S. 340-345 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The apparent discrepancy between theory and experimental practices in field desorption mass spectrometry has encouraged a study attempting to focus theoretical concepts more clearly into forms recognizable to the chemical investigator. Preliminary results indicate that best anode temperature for many compounds is independent of the applied voltage throughout the range available on the Varian MAT CH-5 double focusing mass spectrometer with the electron impact-field ionization-field desorption combined source. Studies of mass transfer indicate that desorption of the sample at the best anode temperature occurs in the absence of the applied field and at a rate which is indistinguishable from the rate of desorption in the presence of the field. These results and other observations, have led us to postulate a new mechanism of ion formation, involving chemical attachment reactions in a thin fluidized system. Clearly, the role of the field in this technique must be the subject of continued study.
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  • 62
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    Biological Mass Spectrometry 3 (1976), S. 81-87 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Thirty-six Δ5- and 5α-3β-hydroxysteroids have been oxidized with cholesterol oxidase to give the corresponding Δ4- and 5α-3-ketosteroids, respectively. The mass spectral characteristics of the products (or their trimethylsilyl ether derivatives, in the case of 3-keto-hydroxysteroids) varied considerably, depending especially on the nature of the C-17 sidechain. The ion of m/e 124 (or its equivalent) from cleavage of ring B was frequently a major fragment from Δ4-3-ketosteroids, but in some instances was of insignificant abundance. Trimethylsilylation of the product of the oxidation of neoergosterol gave neoergosterone enol-trimethylsilyl ether. Fragmentations of the sidechain oredominated in the mass spectra of the 5α-3-ketosteroids.
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  • 63
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    Biological Mass Spectrometry 3 (1976), S. 97-99 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 64
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Gas chromatographic analysis of the products of reaction of diazomethane with tolbutamide and chlorpropamide indicates the formation of three compounds in both cases. As expected, N-methylation (at sulfonamide nitrogen) is the predominant reaction; minor amounts of O-methylated product are also observed. The third product in both cases is the N-methylsulfonamide formed by decomposition of the N-methylated sulfonylurea during gas chromatography. Electron impact and chemical ionization mass spectrometric analysis, as well as 1H nuclear magnetic resonance examination of samples collected from gas chromatography, confirm the structural assignments. Additionally, proton magnetic resonance analysis of the crude reaction products established that N-methylsulfonamides are not formed in the course of the diazomethane reaction and that the O-methylated derivatives are true products of the reaction. The use of a paramagnetic shift reagent allowed direct estimation of the ratios of N- to O-methylation, and the demonstration that these ratios are not vitiated during gas chromatographic analysis.
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  • 65
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    Biological Mass Spectrometry 3 (1976), S. 127-136 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The mass spectroscopic behaviour of prostaglandin F2α and its methyl ester has been studied. Mechanisms are suggested for the formation of the prominent ions in the spectra of these compounds. The proposed fragmentation pathways have been confirmed with the aid of low electron voltage spectra, measurements on metastable ion decompositions, high resolution mass measurements and deuterium labelling.
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  • 66
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    Biological Mass Spectrometry 3 (1976), S. v 
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 67
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    Biological Mass Spectrometry 3 (1976) 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 68
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    Biological Mass Spectrometry 3 (1976), S. 155-160 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The β, γ and δ isomers of bilirubin-IX show a decreased stability as compared with the IXα isomer; characteristic mass spectra are obtained only for the tetrakis-(trimethylsilyl) derivatives of the IXα and IXγ isomers. Hydrogenation of the vinyl substituents increases the thermal stability of the bilirubins and gives rise to a characteristic mass spectrum for the tetrakis-(trimethylsilyl) derivative of meso-bilirubin-IXδ. The ethyl anthranilate azopigments derived from the four bilirubins yield characteristic mass spectra, except for the two unstable divinyl substituted azodipyrroles (mol.wt. 416), derived from bilirubin-IXβ and IXδ. The corresponding mol.wt. 420 azopigments derived from the hydrogenated bilirubins are thermally stable. Elucidation of mass spectral fragmentation pathways is facilitated by the varying positions of the substituents and by deuterium labelling, and permits the assignment of structures to the various isomeric azodipyrroles.
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  • 69
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The electron impact and chemical ionization (isobutane) mass spectra of the TMS derivatives of 20-hydroxy-5α-pregnan-3-ones and 20-hydroxy-4-pregnen-3-ones include ions [M — 44]+· attributable to loss of a CH3CHO fragment from C-17 with migration of the TMS group to the charge-retaining fragment. Mass spectra of isotopically labelled ([3-18O], [20-18O] and [2H9-TMS]) analogues are consistent with this mechanism; [2H9-TMS] labelling further indicates that subsequent loss of a methyl group from [M — 44]+· ions does not involve the TMS group. Corresponding ions are not observed at significant abundance in the spectra of 20β-trimethyl-silyloxy-5α-pregnane and 20β-trimethylsilyloxy-4-pregnen-3-one 3-O-methyloxime. In the electron impact mass spectrum of the t-butyldimethylsilyl ether of 20β-hydroxy-4-pregnen-3-one, an ion is observed corresponding to loss of 44 atomic mass units from the intense [M — C4H9]- ion.
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    Biological Mass Spectrometry 3 (1976), S. 177-183 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Fragmentation reactions of the biologically important N6-(3-methyl-2-butenyl)adenyl moiety have been re-examined with the aid of systematic deuterium labeling in the sidechain and by examination of the 1- and 7-deazanucleoside analogs. It is concluded that the diagnostic reactions which involve expulsion of C3H7 proceed predominantly by ring closure from the sidechain double bond to N-1 (ion a). Base-containing ions m/e 135 and 148 were confirmed to arise mainly by rearrangement of hydrogen from the methyl terminus to N6 and simple cleavage, respectively, but with significant contribution from other pathways involving transfer of sidechain hydrogens to the base.
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  • 71
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    Biological Mass Spectrometry 3 (1976), S. v 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 72
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Two methods are described for the determination of salbutamol in human plasma. The drug is extracted from the plasma as a salbutamol tetraphenylboron ion pair and determined by gas chromatography mass spectrometry. Trideuterio-salbutamol is used as an internal standard. In the first method an extensive purification procedure is used to separate salbutamol from plasma cholesterol which interferes in the assay. Salbutamol is then determined as its TMS-ether using a multiple ion recording technique to measure the intensity of the fragment ion m/e 369 and the ion m/e 372 from the TMS ether of trideuterio-salbutamol. The second method is based on the ion pair extraction of salbutamol into heptan-3-one and its determination by gas chromatography mass spectrometry as the t-butyldimethylsilyl ether. The base peak in the mass spectrum of the t-butyldimethylsilyl-salbutamol is ion of m/e 495, which is of sufficiently high mass to distinguish it from any of the ions which arise from t butyldimethylsilyl-cholesterol. Six replicate analyses of plasma samples containing 1 ng salbutamol ml-1 were carried out using both methods. When the first method was used the mean value obtained was 1.3 ng ml-1 and the coefficient of variation was 17.7%. When the second method was used the mean value obtained was 0.95 ng ml-1 and the coefficient of variation was 10%. The second method is more rapid and therefore preferable for use in clinical pharmacological studies. This method has been used to determine the plasma salbutamol concentrations at varying times after either a 4mg oral or a 200 μg intravenous dose of salbutamol to man.
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  • 73
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    Biological Mass Spectrometry 3 (1976), S. 241-244 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction products of trifluoroacetic anhydride with peptide amides are identified as stable heterocyclic imidazolin-5(4)-ones, which can be analysed by gas chromatography mass spectrometry. The mass spectra show intense molecular ions and allow the assignment of the amino acid sequence.
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  • 74
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    Biological Mass Spectrometry 3 (1976), S. 245-247 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Field desorption mass spectra of methotrexate and folic acid analogs yield abundant molecular or quasimolecular ions. At emitter currents above the best anode temperature, fragment ions which are useful as further confirmations of structures are observed.
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  • 75
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The identification of a number of metabolites of the novel antiarrhythmic agent, α,α-dimethyl-4-(α,α,β,β-tetrafiuorophenethyl)benzylamine (MK-251), is presented. The compound is extensively metabolized by dog, monkey, baboon and man. Similar metabolic profiles were obtained for all species. Isolation and purification were accomplished by solvent extraction and chromatographic (column, gas and thin-layer) procedures. Gas chromatography, derivatization, infrared, nuclear magnetic resonance and particularly combined gas chromatography low and high resolution mass spectrometry techniques were employed to characterize the metabolites. The major urinary and plasma metabolites were identified as 2-[4-(α,α,β,β-tetrafluorophenethyl)phenyl]-2-propanol and its glucuronide conjugate. Other metabolites characterized were: the N-glucuronide of MK-251; 2-[4-(α,α,β,β-tetrafluorophenethyl)phenyl]propene; 2-nitro-2-[4-(α,α,β,β-tetrafluorophenethyl)phenyl]propane; α,α,β,β-dimethyl-4-(α,α,β,β-tetrafluorophenethyl)benzyl methyl ether; and 4-(α,α,β,β-tetrafluorophenethyl)acetophenone. The O-methyl ether metabolite represents the first instance of in vivo alkylation of a tertiary alcohol. Tentative identification was made for the N-hydroxy analog of MK-251 and for the glycol analog of 2-[4-(α,α,β,β-tetrafluorophenethyl)phenyl]-2-propanol. The observed pharmacological response appears to result mainly from MK-251 and not from the four metabolites.
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  • 76
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Twenty-five metabolites were isolated from the urine, feces or plasma of sheep given single oral doses of [14C]crufomate (4-t-butyl-2-chlorophenyl methyl methylphosphoramidate). These metabolites resulted from one or more of the following transformations: oxidation of a methyl group in the t-butyl moiety to yield either an alcohol or a carboxylic acid; hydrolysis of the phosphate and phosphoramidate bonds; oxidation of the N-methyl group to yield N-formyl phosphoramidates; methylation of the N-formyl group to yield N-methyl-N formthyl phosphoramidates; oxidative N-demethylation; conjugation with glucuronic acid. No ring-hydroxylation or dechlorination was observed, and no crufomate was isolated from the urine, feces or plasma.
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  • 77
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Seven sheep metabolites of crufomate (4-t-butyl-2-chlorophenyl methyl methylphosphoramidate) were characterized as glucuronide conjugates by interpretation of mass spectral data obtained from the pertrimethylsilyl derivatives and the trimethylsilyl derivatives of the methyl esters.
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  • 78
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: Quadratic isoparametric elements which embody the inverse square root singularity are used in the calculation of stress intensity factors of elastic fracture mechanics. Examples of the plane eight noded isoparametric element show that it has the same singularity as other special crack tip elements, and still includes the constant strain and rigid body motion modes. Application to three-dimensional analysis is also explored. Stress intensity factors are calculated for mechanical and thermal loads for a number of plane strain and three-dimensional problems.
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  • 79
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    International Journal for Numerical Methods in Engineering 10 (1976), S. 39-58 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: A finite element formulation is presented to study the non-linear buckling of arbitrary shallow elastic thin shells with general boundary conditions and subjected to conservative pressure loading. Pre and post buckling behaviour of a large number of shallow and semi deep doubly curved shells is studied in detail. Unsymmetrical bifurcation paths of a shallow spherical shell subjected to uniform inward pressure are also investigated.
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  • 80
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    International Journal for Numerical Methods in Engineering 10 (1976), S. 253-262 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: The transmission-line matrix method is a time-domain numerical method for solving wave problems. This paper describes how a minor change in the computer program for loss-free dielectrics extends the method to include dielectric losses. Results are given in terms of the wave impedance of a waveguide with losses, and also in terms of power decay due to losses in the dielectric of a resonant cavity.
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  • 81
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    International Journal for Numerical Methods in Engineering 10 (1976), S. 301-343 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: This paper is concerned with the development of a numerical procedure for solving complex boundary value problems in plane elastostatics. This procedure - the displacement discontinuity method - consists simply of placing N displacement discontinuities of unknown magnitude along the boundaries of the region to be analyzed, then setting up and solving a system of algebraic equations to find the discontinuity values that produce prescribed boundary tractions or displacements. The displacement discontinuity method is in some respects similar to integral equation or ‘influence function’ techniques, and contrasts with finite difference and finite element procedures in that approximations are made only on the boundary contours, and not in the field. The method is illustrated by comparing computed results with the analytical solutions of two boundary value problems: a circular disc subjected to diametral compression, and a circular hole in an infinite plate under a uniaxial stress field. In both cases the numerical results are in excellent agreement with the exact solutions.
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  • 82
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    International Journal for Numerical Methods in Engineering 10 (1976), S. 423-435 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: The application of the finite element method to the supersonic flutter of circular cylindrical shells subjected to internal pressure and axial compression is presented. A circular cylindrical shell element is used. The element stiffness, mass and initial stiffness matrices are given. The element aerodynamic matrix is derived based on a first order high Mach number approximation to the linear potential flow theory. The eigenvalue problem is solved by the QR algorithm. Numerical results are presented and these are compared with analytical solutions and experimental data.
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  • 83
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    International Journal for Numerical Methods in Engineering 10 (1976), S. 401-412 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: A straightforward and general computer program for assembling and solving (using Gauss elimination technique) widely sparsed finite element matrix equations with very large bandwidth and capable of handling different degrees-of-freedom and variable bandwidth at different nodes, is described herein. The program assembles any type of finite elements having arbitrary number of nodes and each node may have differnt degrees-of-freedom. It requires only a small core memory in the computer, although a fast random access device is also needed. The two very important features of this program are (i) it does not store any zero submatrices within the band and (ii) during the solution of equations all operations dealing with zero submatrices within the band are automatically skipped and thus the savings of a considerable amount of disc storage space and computer time can be effected in many cases. Another feature is that many right hand sides can be handled simultaneously. Hence the program is very economical for structures having widely sparsed matrix equations. A listing of the computer program written in FORTRAN IV for CDC 6400 computer is readily available from the authors, but unfortunately could not be given here because of lack of space. The program is so general that it can be used to solve a wide class of finite element problems without actually having to understand fully the techniques behind it.
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  • 84
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    International Journal for Numerical Methods in Engineering 10 (1976), S. 465-470 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: The Peaceman-Rachford ADI technique is a well-known iterative method for solving large systems of linear equations arising from finite difference methods of solution of partial differntial equations. The present note demonstrates how the algorithm can be conveniently rearranged for computation in a virtual storage system with paging. Timing results are given for a sample problem typical of those encountered in nuclear diffusion computation.
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  • 85
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    International Journal for Numerical Methods in Engineering 10 (1976), S. 472-474 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
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  • 86
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    International Journal for Numerical Methods in Engineering 10 (1976), S. 478-484 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: A procedure for numerical quadrature over a semi-infinite range is described which does not require storing weights or nodes. It is applicable to a wide variety of integrands including oscillatory functions and forms with integrable singularites. A computer program and numerical examples are presented.
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  • 87
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    International Journal for Numerical Methods in Engineering 10 (1976) 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
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  • 88
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    International Journal for Numerical Methods in Engineering 10 (1976), S. 565-577 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: In applications of the finite element method to complicated nonlinear problems, it is proposed to simplify the operator in each element, typically by a linerization process. Local approximations can then be more easily constructed in the usual manner, and a proper assembly can be made. Such an approach would lead to an approximate global variational statement; or if the variational principle exists but is hard to handle, it should suggest an iterative scheme with a built-in physical basis, hence a better chance to converge. The case of high subsonic flow over a circular cylinder is studied in detail by this method. With linear triangular elements, numerical results are obtained for 100 nodal unknowns in each quadrant. The convergence is extremely rapid up to a free stream Mach number of 0.42, slightly above critical. The accuracy is excellent as compared against Imai's analytical results.
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  • 89
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    International Journal for Numerical Methods in Engineering 10 (1976), S. 637-645 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: An automated digital computer procedure is presented in this paper which enables efficient solution of the eigenvalue problem associated with the supersonic panel flutter phenomena. The step-by-step incremental solution procedure is based on an inverse iteration technique which effectively utilizes solution results from the previous step in determining such results during the current solution step. Also, the computations are limited to the determination of a few specific roots only, which are expected to contain the flutter mode, and this is achieved at each step without having to compute any other root.The structural discretization achieved by the finite element method yields highly banded stiffness, mass, and aerodynamic matrices; the aerodynamic matrix evaluated by the linearized piston theory is real but unsymmetric in nature. The solution algorithm presented in this paper fully exploits the banded form of the associated matrices, and the resulting computer program written in FORTRAN V for the JPL UNIVAC 1108 computer proves to be most efficient and economical when compared to existing procedures of such analysis. Numerical results are presented for a two-dimensional panel flutter problem.
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  • 90
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    International Journal for Numerical Methods in Engineering 10 (1976), S. 708-712 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: The quadrature rule for a finite interval obtained by transforming to an infinite range and applying the midpoint rule is examined. It is found that the condition required to make the quadrature exact for a constant integrand imposes severe practical limits. The method is very good for integrands with singularities near the endpoints but ineffective for oscillatory integrands.
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  • 91
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    International Journal for Numerical Methods in Engineering 10 (1976), S. 845-852 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: An accurate reduction scheme for structural eigenvalue problems is deduced from a variational theorem in which the displacement, velocity and/or momentum fields are taken to be independent.
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  • 92
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    International Journal for Numerical Methods in Engineering 10 (1976), S. 885-891 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: This paper compares three methods for dealing with an exterior boundary value problem by the Finite Element Method, one of which involves using an infinite element. The methods are illustrated by application to the problem of ground water flow round a tunnel with permeable invert. The use of a special trial function with a variable parameter in the infinite element gives a particularly efficient method of solution.
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  • 93
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    International Journal for Numerical Methods in Engineering 10 (1976), S. 809-825 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: This paper presents the formulations of essentially one-dimensional least squares and Galerkin-least squares finite elements for the numerical solution of two-dimensional laminar boundary layer equations. An iterative technique to cope with the non-linearity of the boundary layer equations, in conjunction with the least squares finite element method, is proposed. Through exhaustive numerical investigations in the retarded flow over a plate, flow past a circular cylinder, the flow past an elliptic cylinder, the accuracy and applicability of the proposed method are demonstrated.
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  • 94
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    International Journal for Numerical Methods in Engineering 10 (1976), S. 958-959 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Additional Material: 3 Ill.
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  • 95
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    International Journal for Numerical Methods in Engineering 10 (1976), S. 968-973 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: It is shown that an apparently sound selection of trial functions can give rise to hybrid elements with rank deficient stiffness matrices and unused interior fields. An account is given of modifications which overcome these problems for a particular plate bending element.
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  • 96
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    International Journal for Numerical Methods in Engineering 10 (1976), S. 976-976 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
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  • 97
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    International Journal for Numerical Methods in Engineering 10 (1976), S. 1007-1019 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: The shape of a plate in plane stress is determined, such that the maximum elastic stress corresponding to given loads is minimized. The shape of the boundary is approximated by a series and optimization is carried out by solving a sequence of linearized minimum-maximum problems using linear programming. The optimization problem is extended to include multiple loading cases and geometrical constraints. The stress derivatives are found using analytical expressions for stiffnesses and stiffness derivatives of the finite elements. For the optimum design of a hole in an infinite plate under biaxial stretching the numerical result is compared with an analytical solution. As another example the method is used to optimize the edge shape of a shape of a junction in a web frame.
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  • 98
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    International Journal for Numerical Methods in Engineering 10 (1976), S. 1021-1046 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: Continuous (integral) and discrete (point-matching) least-squares methods are presented for linear and non-linear problems in boundary-value, eigenvalue, and initial-value form. The history is traced, and important theoretical and practical results are summarized. A comprehensive sample of the literature is presented, indexed to show type of application, version of least squares used, and results of comparison studies. The advantages of least-squares methods are discussed, including convenience in formulation and error evaluation, generality of mixed and local (finite element) versions, and performance that is competitive with other methods.
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  • 99
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    International Journal for Numerical Methods in Engineering 10 (1976), S. 1125-1142 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: An algorithm is presented which generates an element stiffness matrix for non-prismatic beam-column members using Newmark's numerical procedure of successive approximations. The resulting element stiffness matrix on element co-ordinates is fond to be in excellent agreement with those available for limiting cases. An approximate stability analysis conducted on the covergence of the numerical scheme shows that the proposed algorithm is stable. The critical buckling loads for various and conditions are computed as part of the computational scheme. A computer program listing in FORTRAN IV is included which will handle essentially and order and/or kind of non-prismaticity of beam elements. The results are presented in the conventional and convenient coefficient format.
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  • 100
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    International Journal for Numerical Methods in Engineering 10 (1976), S. 1153-1175 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: It is first shown that the two-dimensional linearized ship wave problem can be recast as the sum of a radiation and a diffraction problem for simple harmonic waves. Each problem can be solved by a hybrid element method (HEM) where conventional finite elements are used near the body and analytical solutions are used in the remaining infinite regions (super-elements). Variational principles which incorporate the matching conditions between regular and super-elements as natural conditions are derived. Numerical examples are presented. The theoretical aspects for extending the above ideas to a three-dimensional ship wave problems are also described.
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