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  • 1
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1997 (1997), S. 2019-2030 
    ISSN: 0947-3440
    Keywords: Calixarenes ; Macrocycles ; Fragment condensation ; Stepwise strategies ; X-ray analysis ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of special calixarenes and calixarene-like macrocyclic compounds via stepwise procedures and fragment condensation is reviewed. Among the compounds available are exo- and endo-calixarenes consisting of different phenolic units, having bridges other than methylene or showing inherent chirality (Cn-symmetry). Macrobi- and -tricyclic molecules such as bridged calixarenes, double calixarenes, bicyclocalixarenes and annelated calixarenes are also described. Single crystal X-ray structures are reported for several compounds. Some properties like conformational barriers, pKa values or the ability to complex metal ions are discussed, showing the potential of these compounds which may (only) be produced by directed synthesis.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A series of bridged calix [4] arenes (5-10 methylene groups in the bridge) were synthesized and transformed into their tetraester derivatives by reaction with ethyl bromoacetate. The stability constants for complexes of the tetraester derivatives with sodium, potassium and silver cations, determined in methanol by spectroscopic or potentiometric techniques, show a drastic decrease (more than 105 for Na +) for the shorter methylene chains. 1H NMR studies demonstrate a conformational rearrangement of the calixarene part to fourfold symmetry to be necessary for the complexation of a cation, which is prevented by the shorter chains. This is further confirmed by the X-ray structure of a tetraester derivative with a CH2CH2COCH2CH2 bridge; crystals were monoclinic, space group P21/c,a = 11.847(2), b = 39.773(5), c = 12 · 127(2) Å, β = 109.24(1), V = 5395.1 Å3, Z = 4, Dx = 1.186 Mg m-3.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0899-0042
    Keywords: chromatography ; chiral stationary phases ; separation of enantiomers ; CD spectra ; C4 and C2 symmetry ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Various possibilities to obtain intrinsically chiral calix[4]arenes are discussed. The enantiomers of three 1,3-dietheresters and one monoether compound derived from dissymmetric calix[4]arenes with C4 symmetry were separated by HPLC using chiral stationary phases and characterized by their CD spectra. © 1993 Wiley-Liss, Inc.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 0570-0833
    Keywords: calixarenes ; hydrogen bonds ; solvation ; supramolecular chemistry ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1998 (1998), S. 155-161 
    ISSN: 1434-193X
    Keywords: Mechanical bonding ; Interlocked molecules ; Template synthesis ; Calixarenes ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of the amide-based rotaxane 7a bearing calix[4]arene blocking groups is described for the first time. While rotaxane formation fails if a calix[4]arene is functionalized at the upper rim with only an amino or methylamino group lacking any spacer, the prolonged amine 5a works successfully as stopper unit preventing dethreading of the dimeric wheel 1a by its size. Rotaxane formation of 8b was observed only by MALDI-TOF mass spectrometry of the reaction mixture of the amine 5b, the axle 6 and 1a. With the larger trimeric wheel 1b no stable rotaxane could be obtained. It either does not act as a concave template or its opening is too wide, even for the bulky calixarene stoppers.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Chichester, West Sussex : Wiley-Blackwell
    ISSN: 0170-4214
    Keywords: Mathematics and Statistics ; Applied Mathematics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics
    Notes: Recent monographs and research articles have demonstrated that the highly complicated bifurcation structure, which usually arises in the presence of high symmetries, can often be systematically reduced with group theoretic concepts. Equivariant branching theorems and bifurcation subgroups have been the principle tools in this direction of investigation. The generalizations that we give allow the discussions of new classes of problems and the weakening of the usual hypotheses of absolute irreducibility of the group representation or of the appropriate subspaces. These extensions are illustrated in the case of a class of planar semilinear elliptic partial differential equations, which are usually treated as model problems in fluid mechanics and chemical reactions.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 0730-2312
    Keywords: fatty acid-binding protein ; mechanism of action ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Mammary-derived growth inhibitor (MDGI), a polypeptide growth inhibitor isolated from lactating bovine mammary tissue, previously shown to have extensive sequence homology with fatty acid-binding proteins, was demonstrated to meet the criteria of a fatty acid-binding protein. The protein was found to bind [3H]palmitic acid in a saturable manner and to be complexed with endogeneous free fatty acids. [3H]palmitic acid, when bound to the protein, was more rapidly taken up by the target cells (human mammary carcinoma cells [MaTu]) than was free [3H]palmitic acid, suggesting a lipid carrier function for the inhibitor. It is suggested that the fatty acid-binding properties of MDGI may relate to its ability to inhibit cell growth in vitro and to regulate other cellular functions.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die Abhängigkeit der kritischen Konzentration des ternären Systems Polymer-Polymer-Lösungsmittel vom Molekulargewicht kann mittels der folgenden Gleichung ausgedrückt werden: \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm Cc} = {\rm A}\overline {\rm M} ^{ - 2/3} + {\rm c}_{{\rm c}\infty } $\end{document} cc ist die kritische Konzentration, M̄ der geeignete Mittelwert der Molekulargewhichte der beiden Polymeren; A und c∞ sind Konstanten für das gegebene System.Es wird die Möglichkeit erörtert, aus cc und dem Molekulargewicht des bekannten Polymeren - mit Hilfe der Gleichung (1) das Molekulargewicht des zweiten Polymeren zu bestimmen.
    Notes: The dependence of the critical concentration of the ternary system polymer-polymer-solvent on the molecular weight can be expressed by the relation \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm Cc} = {\rm A}\overline {\rm M} ^{ - 2/3} + {\rm c}_{{\rm c}\infty } $\end{document} where cc is the critical concentration, M̄ the appropriate average of the molecular weight of both polymers; A and cc∞ are constants for the given system.The possibility of determining the molecular weight of one of the polymers from the value cc and the molecular weight of the known polymer with the aid of equation (1) is discussed.
    Additional Material: 1 Ill.
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  • 9
    ISSN: 0730-2312
    Keywords: epidermal growth factor receptor ; breast cancer ; immunohistochemistry ; cell proliferation ; receptor phosphorylation ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: The prognostic significance of the epidermal growth factor receptor status (EGF-R-status) for certain human tumors requires the development of antibodies useful for clinical application. We used purified receptor preparations to generate monoclonal antibodies immunoreactive with the EGF-R purified from placenta membranes and A431 tumors. Four of the hybridomas contained antibodies (R2, R3, R5, and R9) which recognized both antigens. Antibody R3 was shown to display the following properties: it binds with a KD value of about 10-9-10-10 M to the receptor, a half maximal inhibition of EGF-binding is achieved at 5 × 10-8 M, and in Western blots of cell membranes R3 specifically detects the EGF-R at 0.1 μ/ml. R3 inhibits EGF-dependent clonogenic growth of NRK cells and completely blocks EGF stimulated autophosphorylation of the receptor. Moreover, R3 also detects EGF-R in paraffin-embedded tissue sections taken from human salivary gland, term placenta, and adult skin and mammary carcinomas. Thus, R3 can be used in retrospective diagnostic clinical studies and might help to develop new immunotherapeutic intervention.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Durch Polykondensation von Diethylentriamin und Triethylentetramin mit Dimethylestern von Säuren, die zwei oder drei Oxyethyleneinheiten enthalten, wurden wasserlösliche Polyamide mit Iminoethylen- und Oxyethyleneinheiten in der Hauptkette erhalten. Die Molekulargewichte lagen im Bereich von M̄n = 5000-7000. Durch potentiometrische bzw. konduktometrische Titration wurden nur 80-85% der erwarteten basischen Gruppen gefunden, was wahrscheinlich durch Verzweigungen zu erklären ist.
    Notes: Water soluble polyamides with iminoethylene and oxyethylene units in the main chain were obtained by condensation polymerization of diethylenetriamine and triethylenetetramine with suitable dimethylesters containing two or three oxyethylene units. The molecular weights were in the range of M̄n = 5000-7000. By potentiometric and conductometric titration only 80-85% of the expected amount of basic groups was found which was probably caused by branching.
    Additional Material: 3 Tab.
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