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  • Organic Chemistry  (20)
  • General Chemistry  (10)
  • Analytical Chemistry and Spectroscopy  (3)
  • Life and Medical Sciences  (3)
  • 68.55.+b  (1)
  • 1980-1984  (34)
  • 1930-1934  (3)
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Keywords
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Years
Year
  • 1
    Electronic Resource
    Electronic Resource
    Photoluminescence of AlxGa1−xAs/GaAs quantum well heterostructures grown by molecular beam epitaxy (1984)
    Springer
    Applied physics 33 (1984), S. 97-105 
    Details
    ISSN: 1432-0630
    Keywords: 78.65.-s ; 71.70.-d ; 68.55.+b
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Low-temperature photoluminescence measurements on nominally undoped AlxGa1−xAs/GaAs quantum well heterostructures (QWHs) grown by molecular beam epitaxy (MBE) exemplified the exclusivelyintrinsic free-exciton nature of the luminescence under moderate excitation conditions. Neither any spectroscopic evidence for alloy clustering in the AlxGa1−xAs barriers nor any extrinsic luminescence due to recombination with residual acceptors has been detected in single and double QWHs when grown at 670 °C under optimized MBE growth conditions. Carrier confinement in AlxGa1−xAs/GaAs QWHs starts at a well width ofL z≌30 nm when x≌0.25. The minor average well thickness fluctuation ofΔL z=4×10−2nm as determined from the excitonic halfwidth allowed the realization of well widths as low asL z=1 nm and thus a shift of the free-exciton line as high as 2.01 eV which is close to the conduction band edge of the employed Al0.43Ga0.57As confinement layer. The measurements further revealed a strongly enhanced luminescence efficiency of the quantum wells as compared to bulk material which is caused by the modified exciton transition probabilities due to carrier localization.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00617615
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  • 2
    Electronic Resource
    Electronic Resource
    Total Synthesis of Neplanocin A (1983)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 66 (1983), S. 1915-1921 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The first total synthesis of racemic neplanocin A (1)After submitting our paper we learned that Arita et al. [J. Am. Chem. Soc.105, 4049(1983)] synthesized the natural enantioner of Neplanocin A. from cyclopentadiene and acylnitroso-3,5-dinitrobenzoic acid is described. The synthesis is suitable for specific isotopic labelling of the hydroxymethyl group of neplanocin A.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19830660702
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  • 3
    Electronic Resource
    Electronic Resource
    Photoreaction of (RS,SR)-3-Phenyl-6-hepten-2-ol. Benzene-Olefin Cycloadditions as a Synthetic Route to [5.5.5.5] Fenestranes. Part IIIFor part II of the series ‘Planarization of Tetracoordinate Carbon Atom’, see [1b]. (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 1930-1941 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Irradiation of (RS,SR)-3-Phenyl-6-hepten-2-ol (3n) gave the photoproducts 6n-10n. Some reactions of 6n and 8n are reported. The regio- and diastereoselectivity observed in the photoreaction of substituted 5-phenylpentenes is discussed with respect to conformational preferences of the compounds to be irradiated.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19840670731
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  • 4
    Electronic Resource
    Electronic Resource
    Photochemistry of 2-Allyl-3-oxo-2,3-dihydro-1H-pyrrole-2-carboxyalates (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 1535-1539 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: On acetone-sensitized irradiation the title compounds 3a-c are converted to 2-allyl-3-hydroxy-1H-pyrrole-2-carboxylates 4 in reasonable yields.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19840670618
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  • 5
    Electronic Resource
    Electronic Resource
    Organizational forms of actin in 13762 ascites mammary tumor cell microvilli (1983)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 3 (1983), S. 491-500 
    Details
    ISSN: 0886-1544
    Keywords: actin ; microfilaments ; oligomers ; transmembrane glycoprotein ; microvilli ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The organization of microvillus actin and its associated proteins have been investigated in sublines of mammary ascites tumors (MAT) with mobile (MAT-B1) and immobile (MAT-C1) cell surface receptors. Microvilli isolated from these sublines differ in morphology (branched for MAT-C1 versus unbranched for MAT-B1) and the presence of a 58,000-dalton polypeptide (58K). 58K is found associated with MAT-C1 microvilli, microvillar cytoskeletons obtained by nonionic detergent extractions, and microvillar membranes prepared under conditions which depolymerize actin microfilaments. By extraction with actin-stabilizing buffers (isotonic Triton-Mg-ATP) microvillar actin can be fractionated into four forms. About 40% of the actin is sedimented at low speed (7,500g, 15 min). The pellets contain microfilaments; actin and α-actinin are the predominant proteins. High-speed pellets from these low-speed supernates contain about 10% of the actin as a transmembrane complex with a cell surface glycoprotein (cytoskeleton-associated glycoprotein, [CAG] 75-80,000 daltons) in MAT-B1 cells or with CAG and 58K in MAT-C1 cells. Transmembrane complexes can be purified from MAT-B1 and MAT-C1 microvillar membranes in Triton-containing buffer by gel filtration or sucrose density gradient centrifugation. The presence of only CAG and actin in the MAT-B1 transmembrane complex strongly suggests the direct interaction of actin and a cell surface component. The high-speed supernates contain soluble actin. By gel filtration or rate-zonal sucrose density gradient centrifugation about 30% of the microvillar actin is found as small oligomers and about 10% as G-actin in this extraction buffer. We suggest that the actin-containing transmembrane complexes may serve as membrane-association sites for oligomeric actin segments and microfilaments and as initiation sites for actin polymerization.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970030516
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  • 6
    Electronic Resource
    Electronic Resource
    Über das 4,4′ - Dipyridyl-amin und seine Derivate (1933)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 137 (1933), S. 141-156 
    Details
    ISSN: 0021-8383
    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/prac.19331370404
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  • 7
    Electronic Resource
    Electronic Resource
    Ein einfaches Verfahren zur Darstellung von reinem, trocknem Bromwasserstoff (1933)
    Weinheim : Wiley-Blackwell
    Zeitschrift für die chemische Industrie 46 (1933), S. 279-279 
    Details
    ISSN: 0044-8249
    Keywords: Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ange.19330462003
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  • 8
    Electronic Resource
    Electronic Resource
    Protamine inhibits platelet derived growth factor receptor activity but not epidermal growth factor activity (1984)
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 26 (1984), S. 205-220 
    Details
    ISSN: 0730-2312
    Keywords: PDGF ; EGF ; receptor ; oncogenes ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Protamine sulfate blocked 125I-PDGF binding to its specific physiological receptor on Swiss mouse 3T3 cells. Reduced 125I-PDGF binding in the presence of protamine sulfate correlated directly with a protamine sulfate dose-dependent decrease in the PDGF-dependent incorporation of [3H]-thymidine into 3T3 cells and a decreased PDGF-stimulated tyrosine-specific protein kinase activity in isolated membrane preparations of 3T3 cells. Protamine sulfate blocked 125I-PDGF binding to simian sarcoma virus transformed cells (SSV-NIH 3T3 and SSV-NPl cells) and to nontransformed cells in a manner qualitatively identical to unlabelled PDGF. In contrast, protamine sulfate enhanced the specific binding of 125I-EGF by increasing the apparent number of EGF receptors on the cell surface. The increase in 125I-EGF receptor binding was not prevented by cycloheximide nor by actinomycin D. Protamine sulfate did not affect 125I-EGF binding to membranes from 3T3 cells or the EGF-stimulated 3T3 cell membrane tyrbsinc specific protein kinase activity, suggesting that protamine sulfate may have exposed a population of cryptic EGF receptors otherwise not accessible. Protamine sulfate was fractionated into four active fractions by Sephadex G-50 gel filtration columns; the half maximum inhibition concentration of 125I-PDGF binding to 3T3 cells of protamines I and II (MW ∼ 11,000 daltons and 7,000 daltons, respectively) is ∼ 0.4 μM. Protamine II (MW ∼ 4,800 daltons) was equally active (half maximum inhibition concentration ∼ 0.4 μM); protamine IV (MW ∼ 3,300 daltons) was substantially less active (half maximum inhibition concentration ∼ 2.8 μM).These investigations have extended previous observations that protamine sulfate is a potent inhibitor of PDGF binding and establish that protamine sulfate blocks PDGF binding at the physiological receptor, preventing PDGF initiated biological activities. Protamine sulfate can be used as a reagent to separate the influence of PDGF and EGF on cells with high specificity and has been used to demonstrate that the receptors on simian sarcoma virus transformed 3T3 cells qualitatively respond identically to protamine sulfate as to unlabelled PDGF and are likely identical to those on nontransformed 3T3 cells.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcb.240260402
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  • 9
    Electronic Resource
    Electronic Resource
    Cytochalasin B binding by human platelets (1982)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 113 (1982), S. 320-323 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Intact human platelets bind cytochalasin B (CB) with a capacity of 100- 120 p mols CB/mg protein or approximately 7 × 104 molecules/cell and dissociation constants (KD) ranging from 2 × 10-8 to 10-6 M. Up to 85% of this saturable binding is displaced by 10-5 M cytochalasin E (CE). This CE-sensitive binding also appears heterogeneous with KD similar to those of the overall binding. The CE-insensitive binding, however, appears as a single component with KD ≌ 4 × 10-7 M. The sedimentable constituents from frozen, thawed, and washed cells also bind CB with KD ranging from 2.4 × 10-8 to 1.5 × 10-6 M and a total capacity of approximately 39 p mols/mg protein which accounts for only 4% of the ligand binding to the intact cell. The major portion (60-80%) of this CB binding is displaceable by 500 mM D-glucose and has a KD of 1.5 × 10-6M, while only 10-15% is CE-sensitive with a KD of 2.4 ± 10-8 M. It is concluded that 95% of the saturable CB binding in platelets is associated with the cytosol of which 80-85% is sensitive to CE and that only 3% of the cellular binding is glucose sensitive, membrane-associated binding. If the CE-sensitive binding associated with the cytosol is entirely to actin, the stoichiometry of this binding is approximately one CB to 30 actin monomers, which is greater by an order of magnitude than that for CB binding to muscle actin.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041130221
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  • 10
    Electronic Resource
    Electronic Resource
    Die Kristallstruktur von α-(tert-Butyloxycarbonylamino)isobuttersäure (1980)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1980 (1980), S. 715-724 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The Crystal Structure of α-(tert-Butyloxycarbonylamino)isobutyric AcidN-(tert-Butyloxycarbonyl)-2-methylalanine crystallizes from ethyl acetate/light petroleum in monoclinic crystals of the space group P21/c, with a = 1085; b = 1099; c = 1172 pm, β = 122.0° and Z = 4. Intermolecular hydrogen bonding between urethane carbonyl and carboxy groups is observed between two antiparallel molecules in the form of 14-membered rings. These rings are somewhat inclined to each other in the (010) plane, and they are linked again by intermolecular hydrogen bonds between the 2-methylalanine-CO and -NH groups in the [010] direction. The resulting layers are held together only via hydrophobia interaction between opposite tert-butyl groups.
    Notes: N-(tert-Butyloxycarbonyl)-2-methylalanin kristallisiert aus Essigester/Petrolether in monoklinen Kristallen der Raumgruppe P21/c, mit a = 1085; b = 1099; c = 1172 pm, β = 122.0° und Z = 4. Je zwei antiparallel angeordnete Moleküle bilden intermolekulare Wasserstoffbrückenbindungen zwischen der Urethancarbonyl- und der Carboxygruppe in Form von 14gliedrigen Ringen. Diese wechselseitig etwas gegeneinander geneigten, ungefähr in der Ebene (010) liegenden Ringe sind in Richtung [010] wiederum über intermolekulare Wasserstoffbrückenbindungen zwischen den 2-Methylalanin-CO- und -NH-Gruppen vernetzt. Die dadurch resultierenden Schichten werden untereinander durch hydrophobe Wechselwirkungen der sich jeweils gegenüberstehenden tert-Butylgruppen zusammengehalten.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198019800511
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