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  • 11
    Electronic Resource
    Electronic Resource
    The effects of Acacia arabica gum on the in vitro growth and protease activities of periodontopathic bacteria (1993)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of clinical periodontology 20 (1993), S. 0 
    Details
    ISSN: 1600-051X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract The antibacterial activity of acacia gum was assessed using fresh isolates and reference strains of Actinobacillus actinomycetemcomitans, Capnocytophaga spp., Porphyromonas gingivalis, Prevotella intermedia and Treponema denticola. A fine aqueous suspension of gum was produced by sonication and then a soluble fraction isolated by centrifugation and membrane filtration. These preparations were incorporated into Columbia agar at doubling concentrations. Growth of P. gingivalis and P. intermedia cultures on the agar was inhibited by whole gum sonicate at concentrations of 0.5–1.0% w/v. Both species showed reduced susceptibility when horse blood was present in the agar. The gum soluble fraction did not inhibit growth of any bacterial culture. The effect of acacia on bacterial proteases was examined with cell sonicates from log phase broth cultures. Enzyme activities were determined by fluorimetric assay with various synthetic peptide substrates. Most protease activities reduced in the presence of 0.5% w/v gum sonicate, with the trypsin-like activities of P. gingivalis and P. intermedia proving most sensitive. The gum soluble fraction was nearly always less inhibitory than the sonicate. The action of acacia gum against suspected periodontal pathogens and their enzymes suggests that it may be of clinical value.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1600-051X.1993.tb00351.x
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  • 12
    Electronic Resource
    Electronic Resource
    Erratum (1968)
    Springer
    Theoretical chemistry accounts 10 (1968), S. 467-467 
    Details
    ISSN: 1432-2234
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00528781
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  • 13
    Electronic Resource
    Electronic Resource
    Non-empirical LCAO-MO-SCF calculations with gaussian type functions on the electrocyclic transformation of cyclopropyl to allyl (1969)
    Springer
    Theoretical chemistry accounts 13 (1969), S. 365-380 
    Details
    ISSN: 1432-2234
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Nichtempirische SCF-MO-Rechnungen mit Gaußfunktionen (GF) für den Übergang des planaren und des unplanaren Cyclopropylkations zum Allylkation wurden vorgenommen. Mit einem Basissatz von 37 GF wurden 34 Rechnungen für 3 disrotatorische und 2 conrotatorische Arten des Übergangs durchgeführt. Um den Einfluß einer größeren Zahl von s-Funktionen am Kohlenstoff zu untersuchen, wurde auch mit einem Basissatz von 43 GF gerechnet. Die Analyse der Energieterme gibt wenig Anlaß zu der Annahme, daß die Art der Ringöffnung nur von der Symmetrie des obersten besetzten Orbitals abhängt.
    Abstract: Résumé Des calculs ab-initio en orbitales gaussiennes ont été effectués sur la transformation électrocyclique de cations cyclopropyliques plans et non plans en cations allyliques. Trois modes disrotatoires et deux modes conrotatoires ont été considérés en utilisant un total de 37 orbitales gaussiennes. Trente quatre calculs ont été effectués dans cette base; l'effet de l'augmentation de la base a été étudié en effectuant d'autres calculs avec une base de 43 orbitales gaussiennes. Une analyse détaillée des termes d'énergie impliqués montre qu'il y a peu de justification théorique pour le postulat selon lequel le mode d'ouverture du cycle dépend seulement de la symétrie de la plus haute orbitale occupée.
    Notes: Abstract Non-empirical molecular quantum chemical calculations have been performed on the electrocyclic transformation of planar and non-planar cyclopropyl cations, to allyl cations, in the LCAO-MO-SCF framework using gaussian type functions as atomic orbitals. Employing a total of 37 GTF, 3 disrotatory and 2 conrotatory modes of transformation have been considered. A total of 34 calculations have been carried out using this basis set; and to investigate the effect of increasing the s basis set on carbon further calculations have been carried out using a basis set of 43 GTF. A detailed analysis of the energy terms involved show that there is little theoretical justification for the postulate that the mode of ring opening depends only on the symmetries of the highest occupied orbitals.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00527014
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  • 14
    Electronic Resource
    Electronic Resource
    Non empirical LCAO-MO-SCF calculations with gaussian type functions on some three membered ring heterocycles (1969)
    Springer
    Theoretical chemistry accounts 15 (1969), S. 225-234 
    Details
    ISSN: 1432-2234
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung An den folgenden Dreiring-Heterocyclen werden nicht-empirische quantenmechanische Rechnungen ausgeführt: Aziridin, Oxiran und Thiiran sowie an den bis heute unbekannten Verbindungen 1-Aziren, 2-Aziren, Oxiren und Thiiren. Die zu den Stickstoffverbindungen gehörenden protonierten Verbindungen werden untersucht und vergleichshalber die gesÄttigten und ungesÄttigten Kohlenwasserstoffe Cyclopropan und Cyclopropen. Gesamtenergien, Eigenwerte und Atombesetzungszahlen werden diskutiert.
    Abstract: Résumé Calculs non empiriques sur les hétérocycles à 3 atomes: aziridine, oxirane, thiirane, et les molécules encore inconnues de 1 azirene, 2 azirene, oxirene et thiirene. On a étudié les espéces protonées des composés azotés et, à titre de comparaison, les hydrocarbures saturés et non saturés isoélectroniques: cyclopropane et cyclopropene. Discussion des énergies totales, des valeurs propres et des populations atomiques totales.
    Notes: Abstract Non empirical molecular quantum chemical calculations have been performed on the three membered ring heterocyclic molecules, aziridine, oxirane and thiirane and the as yet unknown 1 azirene, 2 azirene, oxirene and thiirene. For the nitrogen compounds the corresponding protonated species have been investigated and for comparison the isoelectronic saturated and unsaturated hydrocarbon molecules, cyclopropane and cyclopropene. A discussion is given of total energies, eigenvalues, and gross atomic populations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00526200
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  • 15
    Electronic Resource
    Electronic Resource
    A self consistent field molecular orbital treatment, including excited states of cyclopropane, ethylene oxide and ethylenimine (1968)
    Springer
    Theoretical chemistry accounts 10 (1968), S. 111-118 
    Details
    ISSN: 1432-2234
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Die Elektronenstruktur von Cyclopropan, Äthylenoxid und Äthylenimin wurde mit Hilfe der Pople-Segal CNDO-SCF-MO Methode untersucht. Die Theorie gibt gute Ergebnisse für die Ladungsverteilungen im Grundzustand, für die Dipolmomente und für eine Interpretation der Elektronenspektren.
    Abstract: Résumé Les structures électroniques du cyclopropane, de l'oxyde d'éthylène et de l'éthylèneimine, ont été étudiées en utilisant la méthode S.C.F. de Pople-Segal comportant tous les électrons de valence et négligeant totalement le recouvrement différentiel. La théorie rend bien compte des distributions de charge et des moments dipolaires de l'état fondamental et donne une interprétation raisonnable des spectres électroniques des trois molécules.
    Notes: Abstract The electronic structure of cyclopropane, ethylene oxide and ethylenimine, have been investigated using the Pople-Segal Complete Neglect of Differential Overlap self consistent field molecular orbital method, including all valence electrons. The theory gives a good account of the ground state charge distributions and dipole moments and a reasonable interpretation of the electronic spectra of the three molecules.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00528146
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  • 16
    Electronic Resource
    Electronic Resource
    The electronic structures and energies of borazine, boronimide and dimeric boronimide (1972)
    Springer
    Theoretical chemistry accounts 24 (1972), S. 307-316 
    Details
    ISSN: 1432-2234
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Unter Benutzung Gaußscher Atomorbitale wurden die Elektronenenergien und Strukturen zweier vorgeschlagener Modelle von Borazin mitab inito-Rechnungen untersucht. Man fand, daß das ebeneD 3h -Modell energetisch bevorzugt wird. Die Analyse der Elektronenbesetzung ergibt für Stickstoff- und Boratome im Borazin eine negative bzw. positive Ladung. Berechnungen wurden auch durchgeführt für Borimid und dimeres Borimid. Die Trimerisations- und Dimerisationsenergie von Borimid ergab sich zu −193,8 kcal/Mol bzw. −63,3 kcal/Mol. Die Umlagerungsenergie von Borimid in verschiedenen Konfigurationen wird berechnet und zur Diskussion der Bildungsenergien von Borazin und dimerem Borimid benutzt.
    Notes: Abstract The electronic energies and structures of two proposed models of borazine have been examined byab initio calculations using Gaussian-Type atomic orbitals. It is found that the planarD 3h model is energetically preferred. The electronic population analysis reveals that nitrogen and boron atoms in borazine possess a negative and positive charge, respectively. Calculations have also been performed on boronimide and dimeric boronimide. The trimerisation and dimerisation energy of boronimide is calculated to be −193.8 kcal/mole and −63.3 kcal/mole respectively. The reorganisation energy of boronimide in various configurations is obtained and used to discuss the energetics of formation of borazine and dimeric boronimide.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01007549
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  • 17
    Electronic Resource
    Electronic Resource
    The π-inductive effect of the ammonio (NH 3 + ) group (1968)
    Springer
    Theoretical chemistry accounts 10 (1968), S. 352-356 
    Details
    ISSN: 1432-2234
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Der Einfluß der-NH 3 + -Gruppe auf die π-Elektronenstruktur des 1-Azulenyl- und des 1-Naphthyl-ammoniumkations wurde untersucht. Mit dem von Bishop und Craig angegebenen Potential wurden im Rahmen der PPP-Methode befriedigende Ergebnisse für Elektronenspektren und Ladungsverteilungen der beiden Moleküle erhalten.
    Abstract: Résumé Etude de l'influence du groupe NH 3 + sur les structures électroniques π des cations 1-azulenyl et 1-naphtyl ammonium. En utilisant le potentiel de Bishop et Craig on rend compte raisonnablement du spectre électronique et des distributions de charge dans ces deux molécules dans le cadre de la méthode SCF de Pariser-Parr-Pople.
    Notes: Abstract The influence of the-NH 3 + group on the π electronic structures of 1-azulenyl and 1-naphthyl ammonium cations has been investigated. Using the potential of Bishop and Craig a reasonable account of the electronic spectra and charge distributions in the two molecules has been obtained within the framework of the Pariser-Parr-Pople SCF MO method.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00526500
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  • 18
    Electronic Resource
    Electronic Resource
    Non-empirical LCAO-MO-SCF calculations with gaussian type functions on the electrocyclic transformation of cyclopropyl to allyl (1969)
    Springer
    Theoretical chemistry accounts 14 (1969), S. 370-382 
    Details
    ISSN: 1432-2234
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Nichtempirische SCF-MO-Rechnungen mit Gaußfunktionen (GF) für den Übergang des planaren und des unplanaren Cyclopropylanions zum Allyanion wurden vorgenommen. Mit einem Basissatz von 37 GF wurden 34 Rechnungen für 3 disrotatorische und 2 conrotatorische Übergänge durchgeführt. Sowohl die disrotatorischen als auch die conrotatorischen Übergänge besitzen Aktivierungsbarrieren, von denen diejenigen für die conrotatorischen Übergänge stets kleiner sind. Die Analyse der Energieterme gibt wenig Anlaß zu der Annahme, daß die Art der Ringöffnung nur von der Symmetrie des obersten besetzten Orbitals abhängt.
    Abstract: Résumé Des calculs ab-initio en orbitales gaussiennes ont été effetués sur la transformation de cations cyclopropyliques en cations allyliques. Les barrières d'activation sont toujours plus basses pour la mode conrotatoire que pour la mode disrotatoire. Il est peu évident que l'ouverture du cycle dépende que de la Symmetrie de la plus haute orbitale occupée.
    Notes: Abstract Non-empirical molecular quantum chemical calculations have been performed on the electrocyclic transformation of planar and non planar cyclopropyl anions, to allyl anions in the LCAO-MO-SCF framework using gaussian type functions as atomic orbitals. Employing a total of 37 GTF 3 disrotatory and 2 conrotatory modes of transformation have been considered. A total of 34 calculations have been carried out. In the transformation of planar and non planar cyclopropyl anions to allyl anions, both the disrotatory and conrotatory modes possess activations barriers, those for the conrotatory modes being the lower by substantial margins. A detailed analysis of the energy terms involved show that is little theoretical justification for the postulate that the mode of ring opening depends only on the symmetries of the highest occupied orbitals.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00528236
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  • 19
    Electronic Resource
    Electronic Resource
    Surface modification by plasma techniques. I. The interactions of a hydrogen plasma with fluoropolymer surfaces (1987)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 25 (1987), S. 2643-2664 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The rapid defluorination of fluoropolymer surfaces by their exposure to a hydrogen plasma excited by an inductively coupled RF field has been studied using ESCA. The results are interpreted in terms of a reaction/depth profile; the reaction is not uniform with depth leading to the formation of an approximately 20 Å thick boundary layer of defluorinated material.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1987.080251002
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  • 20
    Electronic Resource
    Electronic Resource
    Comments on “X-ray photoelectron spectroscopy studies of polymer surfaces part 2 melting polyethylene against aluminium” (1977)
    Springer
    Journal of materials science 12 (1977), S. 2547-2551 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00553946
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