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  • 1
    Online Resource
    Online Resource
    Meta-Level Control for Deductive Database Systems (1991)
    Berlin, Heidelberg : Springer Berlin Heidelberg
    Details Availability
    Keywords: Artificial intelligence ; Computer science ; Database management ; Computer Science ; Deduktives Datenbanksystem
    Type of Medium: Online Resource
    Pages: Online-Ressource
    ISBN: 9783540470823
    Series Statement: Lecture Notes in Computer Science 479
    URL: https://doi.org/10.1007/3-540-53754-6
    URL: https://swbplus.bsz-bw.de/bsz322903351cov.jpg
    URL: https://zbmath.org/?q=an:0788.68035
    DOI: 10.1007/3-540-53754-6
    RVK:
    ST 270
    RVK:
    ST 274
    RVK:
    SS 4800
    Language: English
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  • 2
    Online Resource
    Online Resource
    Meta-level control for deductive database systems (1991)
    Berlin [u.a.] : Springer
    Details Availability
    Keywords: Computer science ; Database management ; Artificial intelligence ; Data structures (Computer science). ; Information theory. ; Computer Science ; Artificial Intelligence (incl. Robotics) ; Database Management ; Hochschulschrift ; Deduktives Datenbanksystem
    Description / Table of Contents: A standard deductive database system -- An expert deductive database system -- Discarding irrelevant tuples -- Disregarding irrelevant rules -- Explicit termination of recursion -- Preferring useful rules -- Preferring useful tuples -- Summary and outlook.
    Type of Medium: Online Resource
    Pages: Online-Ressource (VI, 155 S.)
    Edition: Online-Ausg. Berlin [u.a.] Springer 2006 Springer lecture notes archive
    ISBN: 9783540470823
    Series Statement: Lecture notes in computer science 479
    URL: http://www.springerlink.com/content/g835731q1552
    URL: http://www.springerlink.de/openurl.asp?genre=book&isbn=978-3-540-53754-0
    URL: http://dx.doi.org/10.1007/3-540-53754-6
    URL: https://doi.org/10.1007/3-540-53754-6
    URL: https://zbmath.org/?q=an:0788.68035
    DOI: 10.1007/3-540-53754-6
    RVK:
    SS 4800
    RVK:
    ST 274
    Language: English
    Note: Literaturverz. S. [149] - 152 , Zugl.: München, Techn. Univ., Diss.
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  • 3
    Electronic Resource
    Electronic Resource
    On the Hydrolytic Stability of Organic Ligands in Al-, Ti- and Zr-Alkoxide Complexes (1997)
    Springer
    Journal of sol gel science and technology 10 (1997), S. 115-126 
    Details
    ISSN: 1573-4846
    Keywords: metal alkoxide complexes ; β-keto ligands ; hydrolysis ; particle size ; IR ; 13C NMR
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The complexation degrees of Al-, Ti- and Zr-butoxide (M) with unsaturated and saturated β-diketones (3-allylpentane-2.4-dione-APD, acetylacetone-ACAC) and β-ketoesters (methacryloxyethyl-acetoacetate-MEAA, allylacetoacetate-AAA, ethylacetoacetate-EAA) as organic ligands (L) were examined by IR and 13 C NMR spectroscopy and were found to be L:M ≥ 1.5. The hydrolytic stability of the ligands of the metal alkoxide complexes (L:M = 1) during hydrolysis/condensation reactions at the molar ratio h (H2O : OR) = 0.5–2.0 decreases with increasing H〈math〉2O:complex ratio. Furthermore, the ligand stability depends on the type of metal in the complexes and decreases in the order Al- 〉 Zr- 〉 Ti-butoxide complexes at h=1. The ACAC ligand likewise shows in the Al-, Ti- and Zr-butoxide complexes a high hydrolytic stability (95–100%) at h=1 within 7 days. The Ti- and Zr-butoxide complexes with β-ketoesters as ligand show at h=1〉 a release to a different extent e.g., up to 60% in the case of the MEAA-ligand in the Ti-butoxide complex after 2 days. In general, the hydrolytic stability of the ligands in the Ti-butoxide complexes (L:M = 1, h=1) decreases in the order ACAC 〉 APD 〉 AAA 〉 EAA ≥ MEAA. The hydrolysis/condensation reaction of complexes having a weak ligand stability leads to larger particle sizes in the sols than those with stable ACAC ligands. The results contribute to a more controlled synthesis of sols and of new inorganic-organic hybrid polymers via the sol-gel process.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018305811088
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  • 4
    Electronic Resource
    Electronic Resource
    29Si and 17O NMR investigations on Si−O−Ti bonds in solutions of diphenylsilanediol and titanium-tetra-isopropoxide (1996)
    Springer
    Journal of sol gel science and technology 6 (1996), S. 139-149 
    Details
    ISSN: 1573-4846
    Keywords: titanosiloxanes ; siloxanes ; hydrolysis ; condensation ; structural units ; NMR
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The structural units in diphenylsilanediol/titanium-isopropoxide solutions with molar ratio Si:Ti between 1:0.1 and 1:5 were examined by means of 29Si and 17O NMR. The main component in solutions with molar ratio Si/Ti=1:0.1 is the chain-like octaphenyltetrasiloxanediol. With increasing Ti-isopropoxide content (1:0.25–1:05) Si−O−Ti units of the spirocyclic titanosiloxane Ti[O5Si4(C6H5)8]2 prevail in the solutions accompanied by the chain-like tetrasiloxanediol. The 29Si NMR spectra of 1:1 solutions indicate a lot of different Si containing building units with chemical shifts mainly between-40 and-46 ppm. The signals with a chemical shift between-40 and-46 ppm are probably caused by Si atoms which are connected via oxygen bridges directly (Si−O−Ti) or indirectly (Si−O−Si−O−Ti) with titanium. Contrary to the 1:1 solutions only one or two different species with Si−O−Ti units are present in high Ti-alkoxide containing solutions (1:5). 29Si and 17O NMR results reveal a quick hydrolysis of the Ti−O−Si bonds to titanium-oxo-hydroxo-polymers and phenylsiloxanediols or their isopropyl esters after the addition of water to the solutions. This separation into species only containing either Ti−O−Ti or Si−O−Si bonds can entail a decreased homogeneity of the reaction products on a molecular level.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00425971
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  • 5
    Electronic Resource
    Electronic Resource
    On the Existence and Hydrolytic Stability of Titanosiloxane Bonds in the System: Glycidoxypropyltrimethoxysilane-Water-Titaniumtetraethoxide (1998)
    Springer
    Journal of sol gel science and technology 13 (1998), S. 37-43 
    Details
    ISSN: 1573-4846
    Keywords: heterometal bond ; hydrolysis ; condensation ; 17O and 29Si NMR ; titanosiloxane
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Heterometal materials based on glycidoxypropyltrialkoxysilane and titaniumalkoxide are used for optical applications and require a high homogeneity on the molecular level. The presence of heterometal titanosiloxanes, their distribution and hydrolytic stability should influence the homogeneity of these materials. 29Si and 17O NMR spectroscopy has been used to investigate sols with molar ratios Si : Ti = 1 and H2O : OR (H) = 0.5 − 2.0 and their gels after heat treatment at 130°C. The presence of Si—O—Ti bonds in sols with a low water content (H 〈 0.2) and in the corresponding gels was identified by the high-field shift of the 29Si NMR signals of T1 and T2 units of up to 2–3 ppm compared to corresponding signals of homo-condensed Si—O—Si bonds. The existence of Si—O—Ti bonds in the sols is supported by 17O NMR spectra which show a characteristic signal around 340 ppm. A cleavage of the Si—O—Ti bonds occurs with increasing water/OR ratio in the sols. The cleavage of the heterometal bonds and the building up of homo-condensed species leads to a separation into areas with predominantly Ti—O—Ti and Si—O—Si bonds resulting in a decreased molecular homogeneity of the materials.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008638918967
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  • 6
    Electronic Resource
    Electronic Resource
    Bond Angles in Lactones and Lactams (1985)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 68 (1985), S. 76-82 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The carbonyl group in lactones and, to a lesser extent, in lactams tends to show a C—C=O angle that is larger than the O—C=O or N—C=O angle, the difference increasing in magnitude as the ring size decreases. The observed trend provides information on ratios of force constants characterising the flexibility of the s-cis-ester group and may be interpreted in terms of incipient chemical reaction to -O—(CH2)n—C≡O+. Molecular orbital calculations (MINDO/3, MNDO, EH) for model compounds provide an electronic interpretation of this angle difference in terms of an anomeric interaction between the p-type lone pair on the carbonyl O-atom and the antibonding C-O or C-N orbital.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19850680110
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  • 7
    Electronic Resource
    Electronic Resource
    Über die Vinylenhomologen der Di- und Triphenylmethanfarbstoffe, IIIHerrn Prof. Dr. H. Meerwein zum 80. Geburtstag in Verehrung zugeeignet (1959)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 623 (1959), S. 204-216 
    Details
    ISSN: 0075-4617
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Die Synthese von Vinylenhomologen des Michlerschen Hydrolblaus, des Malachitgrüns und des Kristallvioletts wird beschrieben und die farbtheoretische Bedeutung dieser Farbsalze kurz erörtert.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.19596230123
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