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  • Polymer and Materials Science  (69)
  • Computational Chemistry and Molecular Modeling  (3)
  • Wiley-Blackwell  (72)
  • Wiley
  • 1980-1984  (39)
  • 1975-1979  (32)
  • 1960-1964  (1)
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  • Wiley-Blackwell  (72)
  • Wiley
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  • 1
    Electronic Resource
    Electronic Resource
    Ion complexation in nonactin, monactin, and dinactin: A Raman spectroscopic study (1977)
    New York : Wiley-Blackwell
    Biopolymers 16 (1977), S. 157-185 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The ability of the macrotetrolide nactins to complex selectivity with a wide variety of cations makes these ionophorous antibiotics important model systems for the study of biologic ionic transport. We report a Raman spectroscopic investigation of the Na+, K+, Rb+, Cs+, Tl+, NH4+, NH3OH+, C(NH2)3+, and Ba++ complexes of nonactin, monactin, and dinactin in 4:1 (v/v) CH3OH/CHCl3 and in the solid state. The nactins display characteristic spectral changes upon complexation, some of which are specific for a given cation. In the K+, Rb+, Cs+, NH3OH+, and C(NH2)3+ complexes, which are apparently isosteric, the ester carbonyl stretch frequency is found to be linearly proportional to the cation-carbonyl electrostatic interaction energy, as calculated from a simplified model. Deviations for the Na+, NH4+, Tl+, and Ba++ complexes are interpreted as arising from additional nonelectrostatic interactions. Additional information is obtained from other spectral regions and from measurements of depolarization ratios. Spectra of the nactin complexes differ from each other more in the solid state than in solution, reflecting the effects of crystalline contact forces.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1977.360160112
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  • 2
    Electronic Resource
    Electronic Resource
    Nematic polymers: Excluded-volume effects (1979)
    New York : Wiley-Blackwell
    Biopolymers 18 (1979), S. 2315-2322 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We present a theoretical model which describes a cooperative helix-coil liquid-crystal phase transition. We show that this model predicts a first-order phase transition where certain types of chainlike macromolecules in solution make a transition from a nearly coiled to a nearly rigid conformation accompanied by a simultaneous development of long-range nematic-type liquid crystalline orientational order. From this model, the phase boundaries between nematic and isotropic phases are obtained as functions of concentration of macromolecules and of other physical parameters.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1979.360180918
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  • 3
    Electronic Resource
    Electronic Resource
    Strategy for trapping intermediates in the folding of ribonuclease and for using 1H-NMR to determine their structures (1983)
    New York : Wiley-Blackwell
    Biopolymers 22 (1983), S. 59-67 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The major unfolded form of ribonuclease A is known to show well-populated structural intermediates transiently during folding at 0°-10°C. We describe here how the exchange reaction between D2O and peptide NH protons can be used to trap folding intermediates. The protons protected from exchange during folding can be characterized by 1H-nmr after folding is complete. The feasibility of using 1H-nmr to resolve a set of protected peptide protons is demonstrated by using a specially prepared sample of ribonuclease S in D2O in which only the peptide protons of residues 7-14 are in the 1H-form. All eight of these protected peptide protons are H-bonded. Resonance assignments made on isolated peptides containing these residues have been used to identify the protected protons. Other sets of protected protons trapped in the 1H-form can also be isolated by differential exchange, using either ribonuclease A or S. Earlier model compound studies have indicated that H-bonded folding intermediates should be unstable in water unless stabilized by additional interactions. Nevertheless, peptides derived from ribonuclease A that contain residues 3-13 do show partial helix formation in water at low temperatures. We discuss the possibility that specific interactions between side chains can stabilize short α-helixes by nucleating the helix, and that specific interactions may also define the helix boundaries at early stages in folding.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360220111
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  • 4
    Electronic Resource
    Electronic Resource
    Flow birefringence of T7 phage DNA: Dependence on salt concentration (1982)
    New York : Wiley-Blackwell
    Biopolymers 21 (1982), S. 923-934 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We have determined extinction angles and flow birefringence of T7 bacteriophage DNA over a wide range of shear, polymer concentration, and solvent ionic strength. From these data, information on the simple salt dependence of coil permeability to solvent and on short-range intrachain interactions (persistence length) was obtained. At all ionic strengths, our results are consistent with a partially draining coil in the Gaussian subchain dynamical theory of Rouse-Zimm-Tschoegl-Bloomfield. Salt dependence of persistence length is comparable to, although somewhat less than, that obtained previously using similar methods with a fivefold higher-molecular-weight DNA (T2 bacteriophage DNA). Possible reasons for observed discrepancies are analyzed, and the results of this work are compared in detail to other current studies of solvent ionic strength dependence in persistence length and hydrodynamic properties of DNA.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360210506
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  • 5
    Electronic Resource
    Electronic Resource
    Calculation of molecular electric polarizabilities and dipole moments. III. BH moleculeResearch was supported by the National Science Foundation under Grant No. CHE 77-22638. (1980)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 17 (1980), S. 479-483 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We use a previously proposed variation-perturbation method to calculate the electric polarizabilities and the electric dipole moment at equilibrium nuclear distance of the BH molecule. We obtain 3.56 × 10-24 cm3 for the perpendicular polarizability αxx and 3.22 × 10-24 cm3 for the parallel polarizability αzz. Our result for the electric dipole moment μ0 is 1.734 debye units; there is no reliable experimental result to compare it with.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560170309
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  • 6
    Electronic Resource
    Electronic Resource
    Electronic structure and bonding of the pentasulfur hexanitride (S5N6) molecule (1982)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 22 (1982), S. 903-910 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An ab initio version of the Hartree-Fock-Slater method is applied to obtain molecular orbitals and eigenvalues for S5N6. The electronic structure, bonding, stability, and electronic spectrum are discussed.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560220505
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  • 7
    Electronic Resource
    Electronic Resource
    Crystallization of poly(L-proline) in the course of polymerization (1979)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 180 (1979), S. 465-472 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The heterogeneous polymerization of L-proline N-carboxy anhydride was carried out in acetonitrile and benzene, using butylamine as the initiator. Polyproline I was formed in acetonitrile and polyproline II in benzene in the course of the polymerization. The conversion attained 99% and 66% after 1 week-polymerization in acetonitrile and benzene, resp. Extended chain crystals were obtained by the polymerization in acetonitrile. On the other hand, poly(L-proline) obtained by the polymerization in benzene gave aggregates into which many growing chain ends were occluded. The differences in the crystallization behaviour during the polymerization between the two different liquids may be due to the conformation of the resultant polymers. Polyproline I exhibits a cross-section per chain of 0.709 nm2, whereas polyproline II shows only one of 0,386 nm2. The wider the cross-section per chain the more the growing, active chain ends can react with the monomer, giving rise to a higher conversion. In contrast with the case of crystallization of such α-helical chains as poly(L-alanine) during polymerization, hexagonal lamellar crystals were formed.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1979.021800219
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  • 8
    Electronic Resource
    Electronic Resource
    Synthesis and tumor-inhibiting activity of new heparin-bound nitrogen mustard analogues (1981)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 182 (1981), S. 1679-1683 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: New nitrogen mustard analogues in which bis(2-chloroethyl)-amino groups are separated by oxyethylene groups, 1,14-dichloro-3,12-bis(2-chloroethyl)-3,12-diaza-6,9-dioxatetradecan (3c) and 1,17-dichloro-3,15-bis(2-chloroethyl)-3,15-diaza-6,9,12-trioxaheptadecane (3d), were synthesized by reaction of bis(2-hydroxyethyl)amine (2) with bis(2-chloroethyoxy)ethylene (1a) and with 1,11-dichloro-3,6,9-trioxaundecane (1b), respectively, followed by treatment with thionyl chloride. The analogues were then complexed with heparin. The resulting heparin-complexes show inhibiting activity against transplanted Sarcoma-180 A in mice.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1981.021820608
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  • 9
    Electronic Resource
    Electronic Resource
    Activity of a new polyoxime-copper complex in the reversible uptake of molecular oxygen and carbon monoxide, in the polymerization of acrylonitrile, and in the addition reaction of alcohols to acrolein (1975)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 176 (1975), S. 891-903 
    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: Ein neuer Polyoxim-Kupferkomplex wurde aus einem Polyoxim und Kupferacetat dargestellt, und seine Eigenschaften wurden untersucht. Es wird angenommen, daß das Polyoxim hauptsächlich aus 1,2-Bis(hydroxyimino)trimethylen-Einheiten aufgebaut ist. Der Komplex ergibt ein ESR-Signal, das demjenigen eines niedermolekularen Kupfer(II)-Komplexes ähnlich ist und dessen Intensität mit der Zunahme des Kupfergehalts abnimmt. Es wurde gefunden, daß der Komplex ein wirksamer Katalysator bei der Michael-Addition von Alkoholen an Acrolein ist, wobei ausschließlich β-Alkoxypropionaldehyd entsteht, und daß er die Polymerisation von Acrylnitril unter Wasserstoffdruck (40-90 kg/cm2) auslösen kann. Nach der Behandlung mit Hydrazinhydrat in Methanol unter Stickstoff kann der Komplex mit der Zusammensetzung Cu:OX ≈ 1:4 (Cu: Zahl der Kupferatome, OX: Zahl der- Hydroxyimino-Gruppen im Komplex) reversibel etwa 3,2dm3 molekularen Sauerstoff (in Wasser) und 0,8dm3 Kohlenmonoxid (in Methanol) per Mol Kupfer aufnehmen und abgeben. Diese Aktivität wird bei einer Verminderung des Kupfergehalts des Komplexes erheblich herabgesetzt.
    Notes: A new polyoxime-copper complex was prepared from cupric acetate and a polyoxime which is considered to consist largely of 1,2-bis(hydroxyimino)trimethylene units. The properties of the complex were studied. Its ESR spectrum was found to be similar to that of the low molecular weight copper(II) complex, whose intensity decreases with increasing copper content. The complex shows a catalytic activity in the Michael type addition reaction of alcohols to acrolein, yielding exclusively β-alkoxypropionaldehyde. In addition, it initiates the polymerization of acrylonitrile under hydrogen pressure (40 to 90 kg/cm2). Furthermore, the complex with a composition ratio Cu: OX ≈ 1:4 (Cu: number of copper atoms, OX: number of hydroxyimino groups in the complex), after being treated with hydrazine hydrate in methanol under nitrogen, can reversibly take up and release ca. 3,2dm3 of molecular oxygen (in water) and 0,8dm3 of carbon monoxide (in methanol) per mole of copper. These activities decrease remarkably with decreasing copper content of the complex.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1975.021760406
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  • 10
    Electronic Resource
    Electronic Resource
    Studies on reversible uptake of carbon monoxide, catalytic hydrogenation, reactions with benzyl halides and reproducible occurrence of an ESR-signal by a new polyoxime-palladium complex (1975)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 176 (1975), S. 1217-1231 
    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: Ein neuer Polyoxim-Palladium-Komplex wurde aus Bis(benzonitril)palladiumchlorid und einem Polyoxim dargestellt, das hauptsächlich aus 1,2-Bis(hydroxyimino)trimethylen-Einheiten besteht. Seine physikalischen und chemischen Eigenschaften wurden im Vergleich zu seinen monomeren Analoga untersucht. Es wurde gezeigt, daß der Palladiumgehalt des Komplexes mit der Menge des eingesetzten Palladium-Salzes zunimmt und der Komplex bei großem Salzüberschußeine Zusammensetzung von Pd:Cl:OX=1:2:4 erreicht, (OX: Hydroxyimino-Gruppe). Der Komplex zeigte die Eigenschaft, sich unter Abspaltung von HCI in einen Komplex mit der Zusammensetzung Pd:OX = 1 : 4 reversibel umzuwandeln. Der Komplex ist fahig, Kohlenmonoxid aufzunehmen, dessen Volumen nahezu proportional dem Quadrat des Palladiumgehaltes ist. Das Verhaltnis von Palladium zu aufgenommenem CO betragt fur den Komplex mit dem groBten Palladiumgehalt etwa 2: 1. Dieser Komplex ist zur katalytischen Hydrierung befahigt. Im Fall der Hydrierung von Styrol oder Acrylsaure-methylester handelt es sich um eine Reaktion 2. Ordnung in Bezug auf die Pd-Konzentration. Die Umsetzung von Benzylchlorid mit Methanol ergibt in Gegenwart des Komplexes Benzylmethylather. Uberdies wurde gefunden, daRder Komplex reproduzierbar ein ESR-Signal ergibt, das mit der Umwandlung in Zusammenhang steht. Als Ergebnis obiger Experimente resultiert die SchluRfolgerung, daRie Eigenschaften des Komplexes Folge einer spezifischen Pd-Pd-Wechselwirkung sind.
    Notes: A new polyoxime-palladium complex was prepared from bis(benzonitrile)palladium dichloride and a polyoxime which is considered to consist largely of 1,2-bis(hydroxyimino)-trimethylene units. Its physical and chemical properties are studied in comparison with those of the corresponding monomeric analogues. The palladium content of the complex increases with increasing amount of applied palladium salt. In case of a large excess of the salt, the resulting complex has the composition Pd:Cl:OX=1:2:4 (OX being the hydroxyimino groups). The complex may interconvert to a complex with the composition Pd:OX=1:4 and vice versa, by removal and addition of hydrochloric acid. It reversibly takes up carbon monoxide the volume of which being approximately proportional to the square of the palladium content. The ratio of palladium to carbon monoxide, taken up by the complex with the maximum palladium content, is ca. 2:1. This complex shows catalytic activity in hydrogenation. In the case of the hydrogenation of styrene or methyl acrylate, the rate is of second order in palladium content. The reaction of the complex with benzyl bromide in methanol catalytically yields benzyl methyl ether. Furthermore, it exhibits reproducibly an ESR signal, the occurrence of which corresponds to an interconversion. From these results, it is concluded that the specific properties are due to some specific Pd-Pd interactions in the complex.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1975.021760503
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