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  • Articles  (46)
  • Wiley-Blackwell  (24)
  • Springer Nature  (10)
  • Cell Press  (8)
  • EDP Sciences  (4)
  • Molecular Diversity Preservation International
  • 1995-1999  (46)
Collection
  • Articles  (46)
Year
Journal
  • 1
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 129 (1996), S. 227-232 
    ISSN: 0009-2940
    Keywords: β-Formyl esters ; Titanium enolates ; Lithium enolates ; Silyl enol ethers ; Chelate control ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The aldol-type additions of metal enolates 2-Met derived from pinacolone to the chiral β-formyl carboxylate 1a were optimized. The highest trans:cis ratio (86:14) of the products 3 was obtained when the trichlorotitanium enolate 2-TiCl3 was combined with 1a precomplexed with one equivalent of TiCl4. The lithium enolate 2-Li is rather unselective. The simple diastereoselectivity of prochiral enolates 4-Met was first examined with achiral β-formyl carboxylates 1b and 1c. Appropriate reagents made products with high anti or with high syn selectivity available when the unbranched aldehyde 1b was the electrophile. In contrast, the sterically more hindered aldehyde 1c provided syn products with all enolates 4-Met employed. Finally, chiral aldehyde 1a was combined with prochiral enolates 4-Met. Conditions could be found which furnished either the trans/anti or the trans/syn product 7 with good selectivity. The results are discussed and compared with reactions of related metal enolates with aldehydes capable of chelate formation.
    Additional Material: 2 Tab.
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  • 2
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemie in unserer Zeit 32 (1998), S. 107-108 
    ISSN: 0009-2851
    Keywords: Chemistry ; Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemie in unserer Zeit 33 (1999), S. 174-175 
    ISSN: 0009-2851
    Keywords: Chemistry ; Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemie in unserer Zeit 30 (1996), S. 258-260 
    ISSN: 0009-2851
    Keywords: Chemistry ; Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Eine der Haupttätigkeiten des Chemikers besteht darin, Zahlen zu sammeln und zu vergleichen. Ob man nun nur die eigenen Ergebnisse gegenüberstellt oder sich sogar mit seinen Kollegen vergleicht -- immer sollte man darauf achten, das Material ansprechend und vor allem deutlich zu präsentieren. So kommt es auch nicht von ungefähr, daß es nicht an Programmen mangelt, die mehr oder weniger geeignet sind, trockene Zahlen in interessante Graphiken zu verwandeln.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemie in unserer Zeit 31 (1997), S. 254-256 
    ISSN: 0009-2851
    Keywords: Chemistry ; Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The morphology of the principal sections of the gastrointestinal system of two Antarctic seals with different dietary habits, namely, the Weddell seal (Leptonychotes weddellii) and the crabeater seal (Lobodon carcinophagus), has been investigated. Histologically examined by light microscopy, the tissue layers of the gastrointestinal tract of both seals are almost identical to those observed in most other mammals and no major differences in principle organization could be found between the two seal species. The ultrastructure of the gastric and intestinal epithelial cells has been examined and is also closely comparable to that of these cells in other mammals; however, Paneth cells have not been found in our material. In general, therefore, adaptations of the gastrointestinal tract to the aquatic environment or the diet are not obvious at the morphological levels of organization studied.Histochemical differences are found between the two closely related species; mucins of the surface epithelium in the stomach of Weddell seals are highly sulfated, while those in the crabeater seal are not. Mucous neck cells in Weddell seals contain acid mucosubstances, while those of crabeater seals contain neutral ones. Goblet cells in the small and large intestine in Weddell seals contain both neutral and acid mucosubstances. Both mucin types are detected in the crabeater seal; however, the mucins of the colon in the crabeater seal are more highly sulfated than those in the Weddell seal. The ratio of globet cells to enterocytes in the large intestine of crabeater seals is higher than that in Weddell seals. © 1995 Wiley-Liss, Inc.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Materialwissenschaft und Werkstofftechnik 29 (1998), S. 466-475 
    ISSN: 0933-5137
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Low energy IBAD: correlation between process parameters ans film properties for ion beam assisted evaporation and sputter depositionBinary nitride films with Al, Cr and Ti as metal components have been deposited with ion beam assisted evaporation and sputtering (IBAD) and the film properties are investigated in terms of the individual deposition parameters.In the case of ion beam assisted evaporation the flux ratio between the film forming metal atoms and the nitrogen ions from the ion source was shown to enable a quantitative control of the composition and the chemical phases of the films. Detailed studies for TiN reveal the possibilities to manipulate texture and stress, the average grain size and the morphology of the films. Such results are discussed with an extended structure zone model, introducing the energy input per film forming particle as the relevant parameter. Also, the structural film properties and the deposition parameters are quantitatively correlated with the hardness and the beginning of TiN deposition on stainless steel resulted in distinctly improved adhesion properties.For the deposition of TiN with a dual ion beam arrangement in which one beam bundle was directed onto a Ti-target and an other onto the substrate with the growing film, a strong influence of the particle energies and the incidence angles on the film texture and its directional orientation was found. Such effects are quantitatively related to the minimization of the free energy of the films and the influence of preferential re-sputtering effects. For ion beam sputter deposition without simultaneous ion bombardment of the growing film, the texture and the film stress are found to be controlled by energetic particles resulting from elastic backscattering at the target surface.
    Notes: Mittels ionenstrahlunterstütztem Aufdampfen und Aufsputtern (IBAD)wurden binäre Nitridschichten mit Al, Cr und Ti als Metallkomponente deponiert und hinsichtlich ihrer Eigenschaften in Abhängigkeit von den Depositionsparametern Charakterisiert.Beim ionenstrahlunterstützten Aufdampfen konnten durch Variation des Flußratenverhältnisses zwischen den schichtbildenden Metallatomen und den aus der Ionenquelle extrahierten Stickstoffionen die Schichtzusammensetzung und die chemischen Phasenverhältnisse kontrolliert eingestellt werden. Ausführliche Untersuchungen an den TiN-Schichten zeigen, daß auch Textur, Eigenspannungen, mittlere Korngröße und Morphologie der Schichten in weiten Grenzen manipuliert werden können. Ausgehend vom Energieeintrag pro schichtbildendem Teilchen werden die Ergebnisse anhand eines erweiterten Strukturzonenmodells diskutiert. Weiter lassen sich die strukturellen Schichteigenschaften und die Depositionsparameter mit der Härte und der Haftfestigkeit der Schichten quantitativ korrelieren. Durch dynamische Prozeßführung in der Anfangsphase des Schichtwachstums konnte eine deutliche Verbesserung der Haftung von TiN auf Werkzeugstahl erzielt werden.Für die Deposition von TiN mit einer Zweistrahlanordung, bei der ein Ionenstrahlbündel auf ein Ti-Target und ein weiteres auf das Substrat mit der aufwachsenden Schicht trifft, ergibt sich ein deutlicher Einfluß der Teilchenenergien und -auftreffwinkel auf die Schichttextur und deren Ausrichtung. Betrachtungen zur Minimierung der freien Energie in den Schichten und zum Einfluß von präferentiellen Rücksputtereffekten liefern ein quantitatives Verständnis der Effekte bei der Texturbildung. Bei der Ionenstrahl-Sputterdeposition ohne simultanem Substratbeschuß werden Textur und Schichtspannungen durch die vom Sputtertarget kommenden energiereichen Rückstreuteilchen bestimmt.
    Additional Material: 14 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Materialwissenschaft und Werkstofftechnik 28 (1997), S. 355-356 
    ISSN: 0933-5137
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
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  • 9
    ISSN: 0935-9648
    Keywords: Chemistry ; Polymer and Materials Science
    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
    Additional Material: 2 Ill.
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  • 10
    ISSN: 0947-3440
    Keywords: Cyclopropanecarboxylates, 2-siloxy ; Silyl enol ethers ; Diazoacetates ; [2+1] Cycloadditions ; Asymmetric catalysis ; Copper ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: By variation of the aryl substituents of silyl enol ethers 1a-e and 1f-k, the influence of their nucleophilicity on the stereochemical outcome of cyclopropanation reactions was studied. Using the neutral Schiff-base catalyst 2 · Cu(OAc)2, there was only a weak effect. On the other hand, with the cationic bisoxazoline complex 3· CuOTf a remarkable increase in the enantioselectivity was observed with more strongly electron-attracting substituents such as a trifluoromethyl or nitro group.
    Additional Material: 6 Tab.
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