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  • Organic Chemistry  (144)
  • Polymer and Materials Science  (29)
  • 1975-1979  (51)
  • 1950-1954  (37)
  • 1945-1949  (30)
  • 1880-1889
  • 1
    Electronic Resource
    Electronic Resource
    A method for measuring sedimentation and diffusion of macromolecules in capillary tubes by total intensity and quasi-elastic light-scattering techniquesPresented in part at the Symposium on New Generation Instrumentation in Rheology, Rheology Society, Cincinnati, Ohio, January 1973, by M. H. Birnboim. (1975)
    New York : Wiley-Blackwell
    Biopolymers 14 (1975), S. 419-430 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Light scattered from a macromolecular solution in a capillary tube is used to determine both the sedimentation and translational diffusion coefficients. The capillary tube is spun in a preparative centrifuge, removed, and placed in a light-scattering photometer equipped with a scanning mechanism. The intensity distribution of scattered light along the tube represents the concentration profile in the tube and provides the measure of boundary migration. The sedimentation coefficient is determined from this measure and the applied centrifugal field. The diffusion coefficient is obtained from a time-autocorrelation analysis of fluctuations in intensity of light scattered from any fixed point of the profile. These coefficients were obtained for two monodisperse systems, R17 bacteriophage and 28s ribosomal rat liver RNA. The molecular weights obtained from ratios of these coefficients are in good agreement with literature values. In the sedimentation analysis, deviations from linearity between boundary displacement and applied field were found to be less than 1%. This precision confirms that the boundary is stable for the capillary geometry even in the absence of a preformed density gradient. The sedimentation coefficients of identical samples were also measured with the Spinco Model E analytical ultracentrifuge; results of the two methods agree to within 4%.As a consequence of the capillary tube geometry and light-scattering detection, sedimentation coefficients can be obtained from sample volumes of less than 100 μl. This detection techniques is thus far demonstrated to be at least an order of magnitude more sensitive than Schlieren optics, thereby useful when uv absorption is not applicable. For diffusion measurements there are also several inherent advantages. The diffusion coefficient is obtained from the identical sample, and scanning provides the capability to measure D from various parts of the sedimentation profiles and thereby directly explore concentration dependence, homogeneity, and integrity of the sample. The capillary tube with a layer of silicone oil over the sample and centrifugation provides an effective method to cleanse the solution and trap all dust.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1975.360140214
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  • 2
    Electronic Resource
    Electronic Resource
    The Inversion of the Amino Group in Vinylamine, a Flexible Model TreatmentA preliminary account of this work was given at the meeting of the Swiss Chemical Society in Geneva, October 9, 1976. (1978)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 61 (1978), S. 1418-1426 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Flexible model results for the —NH2 inversion in vinylamine are compared with microwave data published by Lovas et al. [3]. The information available on the spacing of inversion levels is found to be sufficient to rule out a planar equilibrium structure. Shifts of rotational constants upon excitation of the inversion are calculated for two predicted paths of motion derived from PRDDO geometry optimization results obtained by MiiIler & Brown [2]. Partial geometry optimization yields a path inconsistent with experiment but the path obtained from complete optimization produces shifts in excellent agreement with the observed shifts. A potential energy function compatible with experimental data on spacing of inversion levels is calculated from the observed inertia defects. The inversion angle at equilibrium is slightly smaller than the angle predicted from PRDDO calculations, and the barrier to inversion, ΔV = 1.08 ± 0.07 kcal/mol, is approximately half the PRDDO value.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19780610426
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  • 3
    Electronic Resource
    Electronic Resource
    A contribution to the mechanism of the “four-center-type” photopolymerization (1977)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 178 (1977), S. 631-634 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1977.021780233
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  • 4
    Electronic Resource
    Electronic Resource
    Polymere mit dem Zentralatom eines makrocyclus in der hauptkette, 2.1. Mitteilung: cf.1. Polykondensationsreaktionen mit Germaniumkomplexen des Phthalocyanins und meso-Tetraphenylporphins (1975)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 176 (1975), S. 831-847 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Dihydroxy(phthalocyanino)germanium (1b) and Dihydroxy(tetraphenylporphino)germanium (3b) react with different monovalent alcohols to afford low-molecular bisalkoxyderivatives (1c-f and 3c-h). With bivalent alcohols and phenols polymers of the structure 5 and 6 or 8a, 9a and 8b, 9b, resp., are obtained.Dichloro(phthalocyanino)germanium (1a) and Dichlor(tetraphenylporphino)germanium (3a) react also with phenol, resp. hydroquinone, to give low-molecular and polymeric phenoxy-derivatives. The reaction of 1b and 3b with mono- and dibasic carboxylic acids leads to the corresponding esters.Dehydration of 3b gives polymeric porphin 15.The IR-spectra of the prepared compounds are discussed and compared with the analogous complexes of hemiporphyrazingermanium.Thermogravimetric and semiconductive measurements (σ298K = 10-10 - 10-15Ω-1 cm-1) are described.
    Notes: Dihydroxyphthalocyaningermanium (1b) und Dihydroxytetraphenylporphingermanium (3b) werden mit verschiedenen einwertigen Alkoholen zu den niedermolekularen Bisalkoxy-Derivaten (1c-f bzw. 3c-h) umgesetzt. Mit zweiwertigen Alkoholen und Phenolen können Polymere der Struktur 5 und 6 bzw. 8a, 9a und 8b, 9b erhalten werden.Dichlorphthalocyaningermanium (1a) und Dichlortetraphenylporphingermanium (3a) reagieren mit Phenol bzw. Hydrochinon ebenfalls zu niedermolekularen und polymeren Phenoxy-Derivaten. Die Umsetzung von 1b und 3b mit ein- und zweibasischen Carbonsäuren führt zu den entsprechenden Estern.Durch Dehydratisierung von 3b kann das polymere Porphin 15 hergestellt werden.Die IR-Spektren der dargestellten Verbindungen werden im Vergleich zu den analogen Hemiporphyrazingermaniumkomplexen diskutiert. Thermogravimetrische und Halbleitermessungen (σ298 K = 10-10 - 10-15Ω-1 cm-1) werden beschrieben.
    Additional Material: 6 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1975.021760401
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  • 5
    Electronic Resource
    Electronic Resource
    Polymere mit dem zentralatom eines makrocyclus in der hauptkette, 3.2. Mitteilung: cf.2.Polykondensationsreaktionen mit zinnkomplexen des meso-tetraphenylporphins, phthalocyanins und hemiporphyrazins (1975)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 176 (1975), S. 1919-1927 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Dihydroxy(meso-tetraphenylporphino)tin (1b), dihydroxy(phthalocyanino)tin (1d), and dihydroxy(hemiporphyrazino)tin (1f) react with bivalent phenols to afford polymers of type B. With 1,2-ethanediol and 1b low molecular compound 3 is obtained, which eliminates 1,2-ethanediol to give poly[oxyethyleneoxy(meso-tetraphenylporphin)stannandiyl] (4). Dehydration of the dihydroxy compounds 1b, 1d, 1f leads to polymers of type C. The IR-spectra of the prepared compounds are discussed; thermogravimetric and semiconductive measurements (σ298K≈10-6-10-16Ω-1cm-1) are described and compared with the analogous complexes of germanium.
    Notes: Dihydroxy-meso-tetraphenylporphinzinn (1b), Dihydroxyphthalocyaninzinn (1d) und Dihydroxyhemiporphyrazinzinn (1f) reagieren mit zweiwertigen Phenolen zu Polymeren des Typs B. Aus Äthylenglykol und 1b läßt sich die niedermolekulare Verbindung 3 erhalten, die unter Äthylenglykolabspaltung Poly[oxyäthylenoxy(meso-tetraphenylporphin)stannandiyl] (4) ergibt.Durch Dehydratation der Dihydroxy-Verbindungen 1b, 1d, 1f lassen sich Polymere des Typs C synthetisieren.Die IR-Spektren der dargestellten Verbindungen werden diskutiert; thermogravimetrische und Halbleitermessungen (σ298K≈10-6-10-16Ω-1cm-1) werden beschrieben und mit den analogen Germaniumverbindungen verglichen.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1975.021760702
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  • 6
    Electronic Resource
    Electronic Resource
    Sur les enzymes amylolytiques (I). L'isolement de l'α-amylase de pancréas (1947)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 30 (1947), S. 64-78 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19470300111
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  • 7
    Electronic Resource
    Electronic Resource
    14-iso-17-iso-Pregnan aus Digitoxigenin und Gitoxigenin (1947)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 30 (1947), S. 2024-2027 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19470300712
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  • 8
    Electronic Resource
    Electronic Resource
    Recherches sur l'amidon XXXVI. La Perméthylation de la lichénine (1948)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 31 (1948), S. 100-103 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19480310121
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  • 9
    Electronic Resource
    Electronic Resource
    Recherches sur l'amidon XXXIX. L'amylose de maïs (1948)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 31 (1948), S. 108-110 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19480310124
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  • 10
    Electronic Resource
    Electronic Resource
    Recherches sur l'amidon, 42. Dosages des acides formés lors de l'oxydation des polyols parle periodate (1948)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 31 (1948), S. 1540-1545 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: On décrit une méthode de dosage des groupes acides, en particulier de l'acide formique, produits lors de l'oxydation des polyols par le periodate. En tenant compte exactement du changement du Ph provoqué par la transition de IO6H2… en IO3, on arrive à, une précision supérieure à celle des méthodes décrites.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19480310613
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