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  • Inorganic Chemistry  (11)
  • Analytical Chemistry and Spectroscopy  (9)
  • Amino Acid Sequence  (4)
  • 1
    Electronic Resource
    Electronic Resource
    Nuclear magnetic resonance studies of internal rotation - IIIFor Part II, see Ref. 1. Rotational barriers in META- and PARA-substituted N, N-dimethylcinnamamides (1971)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 3 (1971), S. 551-556 
    Details
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The rotational barriers about the C—N bond of eight m- and p-substituted N, N-dimethyl cinnamamides have been determined by the iterative total line shape NMR method. The ΔG298·2-≠ values have been correlated with the substituent constants σ, σn and σ+. By comparison of the results with literature data, some conclusions about the accuracy of the barrier determination as well as the transmittance of polar effects in conjugated amides have been drawn.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1270030509
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  • 2
    Electronic Resource
    Electronic Resource
    Dynamic NMR: A new intensity ratio for evaluation of lifetime in paripartite A ⇌ B systems (1976)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 8 (1976), S. 132-136 
    Details
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A simple formula for evaluation of rates of exchange in paripartite A ⇌ B systems is introduced. It is concerned only with the intensity ratio in a two-site system in much the same way as that of Rogers and Woodbrey, but the new formula is also applicable above the coalescence point of the spectrum. The formula has been applied to the classical case of N,N-dimethyltrichloroacetamide. An error analysis demonstrates that the approximations inherent in the derivation of the new formula lead to smaller errors than do those of Rogers and Woodbrey.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1270080306
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  • 3
    Electronic Resource
    Electronic Resource
    Dynamic NMR: A single operational parameter approach for evaluation of lifetime in an uncoupled, equally populated AB system (1974)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 6 (1974), S. 16-19 
    Details
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Two simple formulae involving only one variable are presented for the simple and rapid estimation of the mean lifetime (τ) of exchange in uncoupled, paripartite AB systems. These formulae are shown to provide τ values comparable to those obtained from total line-shape analysis.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1270060106
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  • 4
    Electronic Resource
    Electronic Resource
    Nuclear magnetic resonance studies of internal rotation. VFor Part IV, see Ref. 1. - Rotational barriers of acetylenic amides (1974)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 6 (1974), S. 508-509 
    Details
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The rotational barriers about the C—N bond of the N,N-dimethylamides of propiolic, methylpropiolic and phenylpropiolic acids have been determined by the iterative total line shape nuclear magnetic resonance method.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1270060913
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  • 5
    Electronic Resource
    Electronic Resource
    Nuclear magnetic resonance studies of internal rotation: IVFor Part III, see Ref. 1. - rotational barriers and conformation of phthalic amides (1974)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 6 (1974), S. 20-22 
    Details
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The rotational barriers about the C—N bond of the N,N,N′,N′-tetramethyldiamides of phthalic, isophthalic and terephthalic acids have been determined by the iterative total line shape NMR method. Some evidence about the conformation of these compounds in solution has also been obtained by infrared and dipole moment studies.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1270060107
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  • 6
    Electronic Resource
    Electronic Resource
    Glass formation in the TeO2—MoO3—CeO2 System (1988)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 562 (1988), S. 175-185 
    Details
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Glasbildung im TeO2—MoO3—CeO2-SystemUntersucht wurde die Glasbildung im TeO2—MoO3—CeO2-System, und es wurden niedrigschmelzende stabile Gläser mit bis zu 30 mol-% CeO2 synthetisiert. Infrarot-Spektraluntersuchungen wurden zur Entwicklung von Strukturmodellen für ternäre Gläser angewandt. CeO2 wirkt in erster Linie als Modifiziermittel und verursacht keine nennenswerten Änderungen im Glasnetzwerk und in der Anordnung der Glasbildner. Die molybdänreichen Gläser sind hauptsächlich aus [MoO6]- und [TeO3]-Polyedern zusammengesetzt, wogegen Gläser mit niedrigem MoO3-Anteil aus [TeO4]-Gruppen und isolierten [MoO4]-Einheiten bestehen. Insgesamt gesehen sind die an der Bildung des dreidimensionalen glasbildenden Netzwerks beteiligten Polyeder daher [TeO4]-, [TeO3]-, [MoO6]-, [MoO4]- und [Mo2O8]- (oder [MoO5])-Einheiten. Die strukturelle Affinität einiger ternärer Gläser zu kristallinem Ce4Mo11Te10O59 wird gezeigt. Die hohe elektrische Leitfähigkeit der ternären Gläser wird auf der Grundlage des Elektronensprunges zwischen den Wertigkeitsstufen der Übergangsmetallionen und Anteilen des TeIV-Netzwerks interpretiert.
    Notes: Glass formation in the TeO2—MoO3—CeO2 system was investigated and low melting stable glasses with up to 30 mole-% CeO2 were synthesized. Infrared spectral investigations were used to develop structural models for the vitreous ternary system. CeO2 mainly acts as a modifier without affecting appreciable changes to the glass network and coordination of the glass formers. Glasses in the molybdenum-rich compositional range are mainly composed of [MoO6] and [TeO3] polyhedra, whereas low MoO3-containing glasses consist of [TeO4] groups and isolated [MoO4] units. On the whole, the basic structural polyhedra participating in the formation of the three-dimensional glass forming network are therefore [TeO4], [TeO3], [MoO6], [MoO4], and [Mo2O8] (or [MoO5]) units. The structural affinity of some ternary glasses to crystalline Ce4Mo11Te10O59 is pointed out. The high electrical conductivity of the ternary glasses is interpreted on the basis of electron hopping between transition ions in different valence states and contributions due to the Te(IV) network.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19885620123
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  • 7
    Electronic Resource
    Electronic Resource
    Experimentelle Untersuchungen zum Wolframtransport in fluorhaltigen Systemen (1987)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 547 (1987), S. 216-224 
    Details
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Experimental Investigations on the Tungsten Transport in Systems Containing Fluorine CompoundsInformation on the chemical processes in tungsten incandescent lamps containing gaseous fluorides are obtained by i.r. and u.v. spectroscopic and mass spectrometric analysis of the gasphase as well as by investigating the deposits at the wall and the changes at the filament. Due to the involvement of the wall in the reaction fluorine carrier gases are converted irreversibly into SiF4 which also maintains the chemical tungsten transport. In systems containing fluorine and bromine silicon bromide fluorides are formed.
    Notes: Durch die IR- und UV-spektroskopische sowie massenspektrometrische Analyse der Gasphase sowie die Untersuchung gebildeter Beläge und der Veränderungen am Glühkörper werden Aussagen über die chemischen Vorgänge in Wolframlampen mit fluorhaltigen Füllgasen erhalten. Fluorträgergase werden in der brennenden Lampe durch die Einbeziehung der Wand in das Reaktionsgeschehen irreversibel in SiF4 umgewandelt, das selbst transportaktiv ist. In Fluor und Brom enthaltenden Systemen werden Siliciumbromidfluoride, SiBr4-xFx, gebildet.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19875470425
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  • 8
    Electronic Resource
    Electronic Resource
    Thermodynamische Berechnungen zum Wolframtransport in fluorhaltigen Systemen (1987)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 547 (1987), S. 205-215 
    Details
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Thermodynamic Calculations on the Transport of Tungsten in Systems Containing Fluorine CompoundsInformation on the transport behaviour of tungsten in systems containing fluorine is obtained by a thermodynamic analysis of the systems W(s)-F, W(s)-F-O, W(s)-F-Br, W(s)-F-Br-O, W(s)-Si-F, W(s)-B-F, W(s)-Si-F-Br, and W(s)-B-F-Br. The results are compared with experimental findings. The influence of bromine, oxygen, silicon, and boron on the transport of tungsten is investigated. The nonblackening condition (dλW/dT 〈 0) is fulfilled in systems containing fluorine as well as bromine.
    Notes: Durch eine thermodynamische Analyse der Systeme W(s)-F, W(s)-F-O, W(s)-F-Br, W(s)-F-Br-O, W(s)-Si-F, W(s)-B-F, W(s)-Si-F-Br und W(s)-B-F-Br werden Aussagen zum Transportverhalten von Wolfram in fluorhaltigen Systemen erhalten und mit experimentellen Befunden verglichen. Der Einfluß von Brom, Sauerstoff, Silizium und Bor auf den Wolframtransport wird untersucht. Die Nichtschwärzungsbedingung (dλW/dT 〈 0) ist in fluor- und bromhaltigen Systemen erfüllt.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19875470424
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  • 9
    Electronic Resource
    Electronic Resource
    Restricted rotation of the phenyl group in β-hydroxyphosphonates: Dynamic NMR and semiempirical studies (1994)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 32 (1994), S. 639-645 
    Details
    ISSN: 0749-1581
    Keywords: NMR ; 1H NMR ; 13CNMR ; Dynamic NMR ; β-Hydroxyphosphonates ; Restricted rotation ; Steric effects ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Free energies of activation, ΔG298≠, for the rotation of the phenyl group in the range of 46.06-63.25 kJ mol-1 were observed in some model β-hydroxyphosphonates. These barriers were found to depend on the type of substituents at the phosphorus atom and on the substituents at the β-position with respect to the phenyl ring. The steric origin of this observation is discussed. Dynamic NMR studies were performed in order to determine the activation parameters for the exchange process. For that purpose, variable-temperature 1H and 13C NMR spectra were treated by non-iterative, iterative and iterative double-fit procedures. MNDO, AM1 and PM3 theoretical calculations of the barriers for three of the compounds studied are reported and results are compared with the experiments. It is found that the PM3 results are very close to the experimental data.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1260321102
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  • 10
    Electronic Resource
    Electronic Resource
    Dynamic NMR: A new procedure for the estimation of mixing times in the 2D EXSY experiments. A four-site exchange system studied by 1D and 2D EXSY spectroscopy (1995)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 33 (1995), S. 739-744 
    Details
    ISSN: 0749-1581
    Keywords: 1H NMR ; 2D EXSY NMR ; mixing time ; complete lineshape analysis ; double-fit method ; barriers to restricted rotation ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A procedure for the estimation of the mixing time between the last two 90° pulses in the classic three-pulse sequence NOESY/EXSY is proposed and tested and some considerations for the treatment of the two-dimensional (2D) 1H NMR exchange spectra are given. The rate constants are thus obtained with reasonable precision. This procedure was followed to obtain the 2D spectra of the model compound α-[bis(dimethylamino)methylene]-4-nitrophenylacetonitrile, which represents a four-site exchange system. The barriers to restricted rotations found in this compound were also determined from one-dimensional (1D) 1H NMR spectra, which were processed with the iterative complete lineshape analysis (CLSA) method. The double-fit approach was incorporated in the CLSA method. It is shown that the results from the 2D dynamic NMR spectral studies corroborate those obtained by the CLSA double-fit method.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1260330909
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