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  • 1
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Biopolymers 28 (1989), S. 1505-1514 
    ISSN: 0006-3525
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Time resolved x-ray solution scattering measurements were made during thermal denaturation of DNA from various sources in the temperature range of 20-90°C. Preliminary results on the influence of fragement length, ionic strength, and origin of the DNA on the time course of the scattering are described. Interpretation is based on model calculations of the scattering patterns. The resluts indicate that, for long DNA fragments at very low ionic strength, the melting process is a continuous phenomenon over the whole temperature range. It is accompanied by a progressive decrease of the radius of gyration of the cross section and of the mass per unit length. For short fragments of 146 base pair nucleosomal core DNA, stiffening of the DNA appears to precede a sharp melting transition.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 121 (1988), S. 1495-1500 
    ISSN: 0009-2940
    Schlagwort(e): Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Beschreibung / Inhaltsverzeichnis: Iminophosphoran-vermittelte Syntheses von mesoionischen 1,3,4- Oxadiazolo[3,2a]pyridinylium-2-aminidenDas Iminophosphoran 2 reagiert mit Methylisocyanat zu dem mesoionischen 1,3,4-Oxadiazolo[3,2-a]pyridinylium-2-methylaminid 3, das durch CF3SO3CH3 zum 1,3,4-Oxadiazolo[3,2-a]-pyridinium-Kation 4 methyliert wird. Struktur 4 wurde durch Röntgenstrukturanalyse gesichert. Durch Einwirkung von Base lagert das mesoionische Aminid 3 zum isomeren mesoionischen 1,3,4-Triazolo[3,2-a]pyridinylium-2-olat 11 um. Verbindung 3 wird durch (Arylimino)triphenylphosphorane in die entsprechenden 1,3,4-Oxadiazolo[3,2-a]pyridinium-2-arylaminide 12 umgewandelt, die auch aus Iminophosphoran 2 und Hydroximoylchloriden zugänglich sind.
    Notizen: Reaction of iminophosphorane 2 with methyl isocyanate yields the mesoionic 1,3,4-oxadiazolo[3,2-a]pyridinylium-2-methylamindie 3, which undergoes N-methylation with CF3SO3CH3 to give the 1,3,4-oxadiazolo[3,2-a]pyridinium cation 4. The structure of compound 4 has been established by means of X-ray crystallography. Mesoionic aminide 3 undergoes rearrangement by the action of base to give the isomeric mesoionic compound 1,3,4-triazolo[3,2-a]pyridinylium-2-olate 11. Compound 3 by the action of (arylimino)triphenylphosphoranes is converted into the corresponding 1,3,4-oxadiazolo[3,2-a]pyridinylium-2-arylaminides 12, which can be also prepared from iminophosphorane 2 and hydroximoyl chlorides.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 3
    ISSN: 0025-116X
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Poly(oxythiocarbonyloxy-1,4-phenyleneisopropylidene-1,4-phenylene) (1) was obtained from 4,4′-isopropylidenediphenol (Bisphenol A) and thiophosgene under phase transfer conditions, using quaternary ammonium and phosphonium salts and crown ethers as catalysts. The polymer was identified by IR and 1H NMR spectroscopy, and the molecular weights were estimated from inherent viscosity measurements. The influence of catalysts, solvent and thiophosgene addition was studied in order to find the best conditions. It was found that tetrabutylammonium bromide, dichloromethane and the addition of thiophosgene at once gives the highest yields and inherent viscosities. Other catalysts and solvents were less efficient or unefficient for this reaction.
    Zusätzliches Material: 3 Tab.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 192 (1991), S. 1387-1397 
    ISSN: 0025-116X
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: The classical treatment of inhibition in radical polymerization is complemented by a “sensitivity” analysis. This technique permits to establish which of the possible reactions are relevant or negligible to gain a better insight into the mechanism. The 2,2′-azoisobutyronitrile (AIBN)-initiated polymerization of vinyl acetate was studied in the presence of 5-nitrofuroic acid and 3-(2-furyl)acrylic acid as inhibitors. The monomer dependence of the ratio of rate constants for the degradative transfer and chain propagation, ktrs/kp, and the values of the stoichiometric coefficients for these inhibitors were obtained and analyzed in the light of sensitivity analysis.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 5
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: In this work, we have completed a study of the development of the ovoviviparous lizard Liolaemus tenuis tenuis. Ovoviviparity in this lizard is a condition in which eggs are retained within the reproductive duct for about 60 days. During this period the phases of segmentation, gastrulation, neurulation, presomitic, and somitic embryos transpire. During the months of December and January the eggs are laid, and at this time the embryos are comparable to stage 27 Liolaemus gravenhorsti lizard embryos, or to stage 29 Calotes versicolor lizard embryos. Differentiation of the facial region occurs between Days 12 and 42 after egg laying. Limbs develop rapidly between the 8th and 23rd days. By 53 days the appendicular skeleton is completely formed. After 36 days the mesonephros begins to degenerate, and its function is gradually taken over by the developing metanephros. Newborn lizards do not possess an egg caruncle. During the period up to hatching, there is a great increase of liquid within the egg, presumably amniotic fluid. Cracks develop in the leathery shell shortly before hatching and are, perhaps, the first sign of the onset of hatching. Increase of liquid in the egg during postlaying development accounts for its increase in weight and change in shape. Weight of the embryo at hatching does not exceed 32% of the total weight of the egg.
    Zusätzliches Material: 27 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 6
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Journal of Morphology 189 (1986), S. 121-129 
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: In this study we examined the possible inductive role of the dental papilla from polyphyodont lizard tooth germs. Flank skin sheets of quail ectoderm enzymatically separated from dermal tissue were recombined with lizard tooth papillae and placed on semisolid medium and cultured for 2 days. Subsequently, the recombinants were removed and placed on the chorioallantoic membrane of chick hosts and incubated for 6 days. After this period of 8 days in explant, control tissues differentiated according to their own phenotypes. Lizard dental papilla alone differentiated as fibroblasts. Quail flank skin ectoderm differentiated into epithelial sheets. Intact lizard tooth buds developed into teeth with dentine and incipient enamel. In the best experimental recombinants, advanced and relatively well-constructed teeth were observed, with clear indications of hard tissue deposition in association with quail epithelium. The results show that mesenchyme of the adult lizard dental papilla and embryonic quail ectoderm of heterotopic origin are capable of carrying out the complex sequence of morphogenetic interactions involved in normal odontogenesis.
    Zusätzliches Material: 15 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 7
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 31 (1986), S. 2791-2803 
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: As large polymer samples are quenched rapidly, residual stresses (and birefringence) are frozen into the final part due to the different thermal/contraction histories of the surface and center portions. The present work on polystyrene, a continuation of earlier studies, deals with the effects of sample size and initial temperature; these results are treated with the genral theory of Lee, Rogers, and Woo. Finally, data for two other amorphous polymers, poly(methyl methacrylate) and polycarbonate, are presented; in these cases the simpler theory of Aggarwala and Saibel is used. The theories help explain the relative behavior of the three materials and are qualitatively useful. However, the compexity of the rheooptical response precludes doing a completely rigorous treatment.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 8
    Digitale Medien
    Digitale Medien
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 24 (1986), S. 495-501 
    ISSN: 0887-624X
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Poly(1,4-oxylylenethioethers) were synthesized from 2,5-disubstituted-1,4-bis(chloromethyl)-benzenes and sodium sulfide under phase-transfer conditions. The polythioethers were characterized by elemental analysis and infrared spectroscopy. The effect of the catalyst, solvent, and temperature were studied. Their glass transition temperature and thermal decomposition were determined.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 9
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Letters Edition 26 (1988), S. 201-206 
    ISSN: 0887-6258
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 10
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 25 (1983), S. 559-568 
    ISSN: 0006-3592
    Schlagwort(e): Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Potentiometric and amperometric measurements were made with microbial fuel cells containing E. coli or yeast as the anodic reducing agent and glucose as the oxidizable substrate. The catalytic effects of thionine and resorufin on the anode reaction were investigated. Results on the potentiometry, polarization, and coulombic output of the cells support a mediator-coupled mechanism for the transfer of electrons from the organism to the electrode in preference to a mechanism of “direct” electrochemical oxidation of glucose or its degradation products. Experiments with 14C-labeled glucose show that when a microbial fuel cell produces a current under load, exogenous glucose is metabolized to produce 14CO2. The Coulombic yields of the cells indicate a high degree of energy conversion in these systems.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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