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  • Artikel  (11)
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  • Chemistry  (11)
  • 2020-2024
  • 1990-1994  (7)
  • 1965-1969  (4)
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  • Artikel  (11)
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  • 1
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 191 (1990), S. 1633-1640 
    ISSN: 0025-116X
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: The Friedel-Crafts acylation of various crosslinked polystyrenes, both microporous and macroporous, by ω-halogenoacyl chlorides, a reaction used by others to functionalise polystyrenes, was carefully investigated. As judged by elemental analyses, the desired reaction to give ω-halogenoacyl residues is always accompanied by side reactions. Infrared spectroscopy indicates that these include crosslinking and the introduction of carboxylic acid groups. The side reactions are less pronounced with the ω-chloro compounds and with the 2% crosslinked microporous polymer. For many applications these side reactions will not be important, but in some cases an awareness of their occurrence could be crucial.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    ISSN: 0899-0042
    Schlagwort(e): Chiral stereospecificity ; esterase ; metabolism ; human tissue ; Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Famciclovir is the oral form of the potent antiherpesvirus agent, penciclovir. Hydrolysis of one of the acetyl ester groups of famciclovir creates a chiral centre leading to the possible formation of (R)- and (S)-enantiomers. During its conversion to penciclovir, famciclovir forms two chiral metabolites, namely monoacetyl-6-deoxy-penciclovir and monoacetyl-penciclovir. The absolute configuration and stereospecificity of the monoacetyl metabolites of famciclovir, produced in human intestinal wall extract, were determined using isotopically chiral famciclovir and 13C NMR spectroscopy of the isolated metabolites. 13C NMR showed that the esterase(s), in human intestinal wall extract, hydrolysed the acetyl group preferentially from the pro-(S)-acetoxymethyl group of famciclovir. The specificity of esterase action in forming monoacetyl-6-deoxy-penciclovir and monoacetyl-penciclovir was about 77 and 72%, respectively. © 1993 Wiley-Liss, Inc.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 3
    ISSN: 0899-0042
    Schlagwort(e): chiral stereospecificity ; phosphorylation ; MRC-5 cells ; herpesvirus ; Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Penciclovir is a potent antiherpesvirus agent which is highly selective due to its phosphorylation only in virus infected cells. Phosphorylation of one of the hydroxymethyl groups of penciclovir (PCV) creates a chiral centre leading to the possible formation of (R)- and (S)-enantiomers. The absolute configuration and stereospecificity of the PCV-phosphates produced in cells infected with herpes simplex viruses types 1 and 2 (HSV-1 and HSV-2), as well as by HSV-1-encoded thymidine kinase, were determined using isotopically chiral [4′-13C]PCV precursors and 13C NMR spectroscopy of the isolated metabolites. The absolute configuration of penciclovir-triphosphate (PCV-TP) produced in HSV-1-infected cells was shown to be S with an enantiomeric purity of greater than 95%. However, in contrast to HSV-1-infected cells in which none of the (R) enantiomer was detected, about 10% of (R)-PCV-TP was produced in HSV-2-infected cells. Phosphorylation of PCV by HSV-1-encoded thymidine kinase was found to give 75% (S)- and 25% (R)-PCV-monophosphate. The proportion of the (S)-isomer appears to be amplified in the subsequent phosphorylations leading to the triphosphate. © 1993 Wiley-Liss, Inc.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 29 (1994), S. 326-328 
    ISSN: 0030-493X
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Metastable ion scanning was used to investigate the fragmentation patterns of ethyl(trimethoxy)silane, ethyl(dimethoxy)chlorosilane and ethyl(methoxy)dichlorosilane, their deuterated counterparts and ethyltrichlorosilane. For these compounds the molecule ion has a low abundance using 70 eV electron impact ionization. In all cases the base peak corresponds to the loss of neutral C2H5. When chemical ionization is employed with isobutane, usable peaks representative of the molecule ions are observed.
    Zusätzliches Material: 1 Tab.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 5
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Polymers for Advanced Technologies 5 (1994), S. 473-478 
    ISSN: 1042-7147
    Schlagwort(e): Cyclic polymer ; Poly(dimethylsiloxane) ; Polymer supported reactions ; Polymeric catenanes ; Topological polymer chemistry ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau
    Notizen: Methods for characterising cyclic polymers are illustrated by reference first to dilute solution methods for cyclic poly(dimethylsiloxane) (PDMS) and then to the entrapment of cyclic polymers in networks. Preparative routes to cyclic polymers are then reviewed, including ring-chain equilibration reactions, coupling and condensation reactions and new methods using polymer-supported reagents. Some of the properties of cyclic PDMS are discussed, including differences between ring and chain polymer properties such as their melt viscosities and glass transition temperatures. Methods for preparing the first polymeric catenanes are described, using polymer-supported reagents. Future directions for cyclic polymer chemistry are indicated, including topological polymer chemistry.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 6
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Notizen: The tissue reaction to metallic and nonmetallic implants in the back muscles of New Zealand White Rabbits is presented. These reactions are graded and correlated with the trace metal contained around such implanes. Correlations are drawn as to the acceptability of various materials for the manufacture of surgical implants.
    Zusätzliches Material: 18 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 7
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Notizen: We have used total internal reflection fluorescence (TIRF) to measure the adsorption kinetics of a newly synthesized fluorescent derivative of a triblock copolymer comprising two poly(ethylene oxide) arms connected by a poly(butylene oxide) segment. The composition is (EO)400 (BO)55 (EO)400, in which EO represents ethylene oxide, BO represents butylene oxide, and one or both of the terminal OH groups of the two (EO)400 arms are labeled with tetramethylrhodamine. The poly(butylene oxide) segment binds to hydrophobic octadecyl glass, used as a substratum. The TIRF signal is shown to be derived almost entirely from surface-adsobed polymer. This facilitates calculation of adsorption isotherms from 0.1-0.005% bulk polymer solution by means of diffusion kinetics. Information about the effective thickness of the adsorbed polymer, determined by optical interference microscopy, corresponds with what is known about the conformation of similar molecules at interfaces and indicates monolayer adsorption on the glass. © 1994 John Wiley & Sons, Inc.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 8
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 2 (1968), S. 173-178 
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Notizen: The higher n-alkyl α-cyanoacrylate homologs had been previously found to wet, spread, and rapidly polymerize on tissue substrates whereas the lower homologs do not wet and polymerize slowly. The reverse effect is noted on nonproteinaceous substrates such as distilled water and saline solution. Tissue bonds were prepared and tested in vivo in rats. Bonds prepared with the higher n-alkyl α-cyanoacrylate homologs were found to be stronger than those prepared with the lower homologs. The data are in general accord with the wetting and spreading characteristics of the n-alkyl α-cyanoacrylate homologs. On aluminum surfaces, the opposite effect was noted. Bonds prepared with the lower homologs were stronger than those prepared with the higher homologs.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 9
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Notizen: This work was motivated by the need for a systematic compatibility screen for materials of interest for heart assist devices. A practical polymer screening and monitoring program for biochemical engineering materials was developed. Initial emphasis was placed on screening to measure degradation to low molecular weight, water miscible moieties over simulated in vivo exposure. Infrared spectrographic analysis of the simulated body fluid showed that the level of organic moiety corresponds to general clinical experience. Further confirmation of the technique came from evaluation of control polymers from The University of Texas Drug Research Laboratory. Correlation of results with cell culture viability in the presence of the pseudo body fluid is being carried out.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 10
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 3 (1969), S. 281-289 
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Notizen: The use of cyanoacrylate tissue adhesives provides a quick method of closing wounds by nonsuture techniques. This study was undertaken to determine the relative effects on healing of a number of alkyl α-cyanoacrylate tissue adhesives compared to sutured incisions. Tissue bonds were prepared with the alkyl α-cyanoacrylate adhesives and sutures and tested for bond strength in vivo in rats over periods of 1, 3, 7, 10, and 14 days. A trend of increasing bond strength with the higher homologs was immediately apparent. However, this trend was reversed at the time of the 14 day measurements with the higher homologs of the cyanoacrylate adhesives having the lower bond strength. Microscopic examination of pulled wounds closed with methyl α-cyanoacrylate showed the cause to be substrate failure with the exception of the one hour postoperative samples which demonstrated adhesive failure. Wound failure in the remaining three monomers was cohesive, gradually decreasing to substrate failure at 10 days postoperative. The tensile strength of all wounds closed with tissue adhesive dropped considerably on the third day postoperative.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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