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  • 1980-1984  (29)
  • 1935-1939
  • 1830-1839
  • 1981  (29)
  • Chemistry  (27)
  • Inorganic Chemistry  (7)
  • General Chemistry  (6)
  • Ultrastructure
  • Visual system
Material
Years
  • 1980-1984  (29)
  • 1935-1939
  • 1830-1839
Year
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 216 (1981), S. 491-501 
    ISSN: 1432-0878
    Keywords: Ultrastructure ; Cornea ; Compound eye ; Honey bee (Apis mellifera)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The fine structure of the cornea in an anatomically and functionally specialized part of the honey bee's compound eye (dorsal rim area) was examined by light microscopy, transmission electron and scanning electron microscopy. Under incident illumination the cornea appears grey and cloudy, leaving only the centers of the corneal lenses clear. This is due to numerous pore canals that penetrate the cornea from the inside, ending a few μm below the outer surface. They consist of (1) a small cylindrical cellular evagination of a pigment cell (proximal), and (2) a rugged-walled, pinetree-shaped extracellular part (distal). The functional significance of these pore canals is discussed. It is concluded that their light scattering properties cause the wide visual fields of the photoreceptor cells measured electrophysiologically in the dorsal rim area, and that this is related to the way this eye region detects polarization in skylight.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 1058-1062 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The rates of proton transfer from 2, 4-hexadiene, 1, 3-cycloheptadiene, cyclopentadiene and acetone to t-butoxide have been measured in the gas phase using pulsed-ion-cyclotron-resonance spectroscopy. The rate constants are (units of 10-10 cm3 molecule-1 s-1): 2.7 ± 0.4, 3.8 ± 0.4, 6.1 ± 0.7 and 10.8 ± 1.5, respectively. These results are analyzed in terms of the properties of the encounter complex and reaction transition states. The reaction profile for t-butoxide + cyclopentadiene is modeled using RRKM theory and an estimate for the central barrier height is obtained.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 114 (1981), S. 3634-3642 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Au55[P(C6H5)3]12Cl6- a Gold Cluster of an Exceptional sizeThe reduction of (C6H5)3PAuCl with B2H6 in benzene yields Au9,2[P(C6H5)3]2Cl which is characterized by means of molecular weight determinations as Au55[P(C6H5)3]12Cl6. A simple model, based on an arrangement of close-packed gold atoms, leads to a gold cluster the structure of which is in good agreement with the unusual chemical composition. The Mößbauer spectrum of the compound shows four different kinds of gold atoms: a metallic part (Au13-nucleus), Au atoms coordinated by P(C6H5)3 and Cl ligands, resp., as well as uncoordinated surface gold. The complex can be decomposed by bromine and iodine to (C6H5)3PAuCl, (C6H5)3PAuBr(I), and metallic gold. The thermolysis at 50°C leads to [(C6H5)3P]2AuCl and gold quantitatively.
    Notes: Die Reduktion von C6H5)3PAuCl mit B2H6 in Benzol ergibt Au9,2[P(C6H5)3]2Cl, das mittels Molmassebestimmungen als Au55[P(C6H5)3]12Cl6 charakterisiert wurde. Ein einfaches Modell, beruhend auf einer Anordnung dichtest gepackter Goldatome, führt zu einem Goldcluster, dessen Aufbau mit der ungewöhnlichen chemischen Zusammensetzung in guter Übereinstimmung ist. Das Mößbauer-Spektrum der Verbindung zeigt vier Sorten von Goldatomen: einen metallischen Anteil (Au13-Kern), durch P(C6H5)3-bzw. Cl-Liganden Koordinierte Au-Atome, sowie unkoordi-niertes Oberflächengold. Mit Brom und lod läß sich der Komplex zu (C6H5)3PAuCl, (C6H5)3 PAuBr(I) und metallischem Gold abbauen. Die Thermolyse bei 50°C führt quantitativ zu [(C6H5)3P]2AuCl und Gold.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Syntheses of Biologically Important Carbohydrates, 251) On the Regioselectivity of Sharpless Reaction; The vic. cis-Oxyamination of Unbranched and 3-C-Branched Ald-2-and Ald-3-enopyranosidesThe configurations and the ratios of regioisomeric amino sugars obtained by vic. cis-oxyamination of unsaturated carbohydrates 1, 4, 9, 16, 19, 21 are determined. Due to the ratios of amino sugars from the ald-3-enopyranosides 9 and 16 it is obvious that the regioorientation is probably not directed by the electron density at the double bonds.
    Notes: Die Konfigurationen und die Verhältnisse regioisomerer Aminozucker bei der vic. cis-Oxyaminierung von ungesättigten Kohlenhydraten 1,4,9,16,19,21 werden bestimmt. Die Isomerenverhältnisse der Aminozucker aus den Ald-3-enopyranosiden 9 und 16 zeigen, daß die Regioorientierung wahrscheinlich nicht durch die Elektronendichte an den Doppelbindungen gesteuert wird.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 0009-286X
    Keywords: Anemometrie ; Leitfähigkeitssonden ; Zweiphasenströmung ; Bioreaktor ; Turbulenz ; Blasensäule ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The gas phase reaction of 1,2,4,5-tetracyanobenzene (3) with metal sheets like Cu, Ni, Co, Fe, and Ti exhibits the in situ formation of polymeric phthalocyanine coatings 1. The electrochemical behaviour of layers of 1 is investigated by means of cyclic voltametric measurements. Determination of layer-thickness and electrical resistance is also performed.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Microbial Reduction of 2,2-Disubstituted Cyclopentan-1,3-diones. Synthesis of Chiral Cyclopentane Derivatives Useful as Intermediates for 8-Methyl ProstaglandinsThe microbial reduction of the 2,2-disubstituted cyclopentan-1,3-diones 3a—c giving rise to the chiral compounds 2, 4b and 4c is described.The incubation products can be used as intermediates for 8-methyl prostaglandins.The structures of the fermentatively formed compounds, including their chirality and optical purity have been established by comparison with authentic specimen (cp. 2) or by chemical and spectroscopic methods (cp. 4b, 4c) respectively.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 218 (1981), S. 389-401 
    ISSN: 1432-0878
    Keywords: Visual system ; Retina ; Optic nerve efferents ; Torus semicircularis ; HRP technique ; Catfish
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The retinofugal and retinopetal connections in the upside-down catfish Synodontis nigriventris were studied by use of the horseradish-peroxidase (HRP) techniques, autoradiography, and degeneration-silver methods. An unusual retinal projection to the torus semicircularis as well as projections to the retina from three different sources in the brain are described. After intra-ocular injections of HRP, labeled cells were found in the optic tectum, the dorsomedial optic nucleus and one of the pretectal nuclei. These new findings support the basic hypothesis (i) that neuronal connections are more extensive in primitive brains, and (ii) that the evolutionary development of more complex brains involves the loss of some selected connections.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: This work shows how laboratory experiments may provide parameters which are useful in modeling a commercial process of polystyrene devolatilization. Such processes often occur at temperatures where depolymerization of polystyrene to monomer may be significant. Polystyrene devolatilizers function by forming thin films of the polymer, with styrene loss by flashing and diffusion and styrene generation by depolymerization. The modeling parameters of importance are: depolymerization rate constant, monomer diffusivity, and thermodynamic equilibrium polymer-vapor partition coefficient. Typical levels of styrene in polystyrene in the last stage of devolatilization are 100 to 1000 ppm. Pressures and temperatures in the devolatilizer are often less than 10 torr and greater than 200°C. For styrene-polystyrene the desired parameters have not been reported, nor apparently measured, at the concentration, pressure and temperature levels of interest.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1981 (1981), S. 1545-1549 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Malonodiamidines, III.  -  Synthesis and Condensation Reactions of 1,2,3,4,6,7-Hexahydro-7 imino-1,4-dimethyl-5H -1,4-diazepin-5-oneDiethyl malonodiimidate dihydrochloride (I) and N-methylethylenediamine yield in ethanol the N,N'-bridged malonodiamidine salt 2b, whereas 1 and N,N'-dimethylethylenediamine fail to give the 2b analogous salt 4. Instead the 1 H-1,4-diazepine-5,7-diimine hydrochloride 5 is obtained in low yield. Under hydrolytic reaction conditions the hydrochloride of the title compound is obtained in 56% yield. [3 + 3]-Condensations of the corresponding base 7 with 2,4-pentanedione and α,β-unsaturated carbonyl compounds lead to the diazepines 8, 9, and 10. 1 H-[1,4]diazepino-[5,6-b]quinolines 12a- f are obtained by condensation of 6 with the isatines 11.
    Notes: Malondiimidsäure-diethylester-dihydrochlorid (1) liefert mit N-Methylethylendiamin in Ethanol das N,N'-verbrückte Malondiamidiniumsalz 2b. Umsetzung von 1 mit N,N'-Dimethylethylendiamin führt wider Erwarten nicht zum 2b analogen Salz 4, sondern in geringer Ausbeute zum 1 H-1,4-Diazepin-5,7-diiminsalz 5. Unter hydrolytischen Reaktionsbedingungen wird das Hydrochlorid der Titelverbindung mit 56% Ausbeute erhalten. Die zugrundeliegende Base 7 geht mit 2,4-Pentandion und α,β-ungesättigten Carbonylverbindungen [3 + 3]-Kondensationen zu den Diazepinen 8, 9 und 10 ein. Die Isatine 11 kondensieren mit 7 zu den 1 H-[1,4]Diazepino[5,6-b]-chinolinen 12a- f.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
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