Library

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    A thermodynamic analysis of the amorphous to crystalline calcium phosphate transformation (1978)
    Springer
    Calcified tissue international 25 (1978), S. 59-68 
    Details
    ISSN: 1432-0827
    Keywords: Amorphous calcium phosphate ; Thermodynamics ; Apatite ; Octacalcium phosphate ; Tricalcium phosphate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary A thermodynamic analysis of the precipitation of amorphous calcium phosphate (ACP) and its transformation to crystalline apatite has been made. A nearly constant ion product, over a wide variety of conditions, was obtained for a tricalcium phosphate (TCP)-like phase suggesting that the molecular unit which governs the solubility of ACP may be similar in composition to TCP. The introduction of 10% acid phosphate into the formula for the TCP ion product improves the fit of experimental data and results in an invariant ion product. The stability of ACP in solution was found to be dependent upon its thermodynamic instability with respect to an octacalcium phosphate (OCP)-like phase. The dependence of the induction period for the amorphous to crystalline transformation upon the pH and the Ca/P ratio of the solution is best explained by the assumption that an OCP-like phase is initially nucleated on the surfaces of the ACP particles. The events that occur in the immediate post-transition period suggest the hydrolysis of this OCP-like material to an apatitic phase.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02010752
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    The maturation of crystalline calcium phosphates in aqueous suspensions at physiologic pH (1977)
    Springer
    Calcified tissue international 23 (1977), S. 259-269 
    Details
    ISSN: 1432-0827
    Keywords: Amorphous calcium phosphate ; Apatite ; Calcification ; Octacalcium phosphate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The maturation of calcium phosphate crystals formed by the conversion of spontaneously precipitated amorphous calcium phosphate (ACP) was studied in aqueous media at temperatures ranging from 20° to 37°. Reaction pH was kept at 7.4 with either Hepes buffer or by the pH-stat addition of base. Reaction kinetics were followed by monitoring solution calcium and total phosphate, and, in the pH-stat controlled reaction, by recording the amount of KOH needed to maintain pH. Reaction products were examined chemically and by X-ray diffraction and transmission electron microcopy. The first crystals to form deviated markedly from apatite in morphology, composition, structure, and solubility. They were extremely thin and flaky in appearance, had a low Ca/P molar ratio (1.4), contained an appreciable amount of acid phosphate (16%), and had an exceptionally largea-axis (10.5 Å vs. 9.4 Å for apatite). With maturation, the crystals became thicker but smaller in lateral dimensions, more apatitelike in structure and composition, and less soluble. However, this ripening of the crystals was accompanied by unusual inflections in the solution Ca and total PO4 curves, and, in the case of the pH-stat experiments, in the OH consumption profiles as well. These anomalous post-ACP solution changes suggest that a phase change had taken place during crystal maturation. Although the observed structural and compositional changes are not inconsistent with the perfection of an initially defective apatite, the changes in crystal morphology and the anomalous behavior of the reaction solution may more accurately reflect a conversion of the ACP first into an OCP-like crystalline phase which subsequently hydrolyzes into apatite.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02012795
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    A thermodynamic analysis of the secondary transition in the spontaneous precipitation of calcium phosphate (1978)
    Springer
    Calcified tissue international 25 (1978), S. 209-216 
    Details
    ISSN: 1432-0827
    Keywords: Thermodynamics ; Kinetics ; Apatite ; Octacalcium phosphate ; Tricalcium phosphate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary A thermodynamic analysis has been made of the secondary transition stage in the spontaneous precipitation of calcium phosphate following the amorphous-crystalline transformation. The first formed crystalline material has a solubility similar to that of octacalcium phosphate (OCP) and the computed thermodynamic solubility product remains invariant in the pH range 7.00–8.60. The duration of the secondary stage is sensitive to pH and the transition appears to occur by hydrolysis of the first formed OCP-like phase to a more basic apatitic phase with a tricalcium phosphate (TCP) stoichiometry. The crystalline material at the end of this transition has an invariant solubility product, in the pH range 7.00 to 8.60, when the TCP-like molecular formula is assumed. Changes in the solution chemistry which accompany the solid-tosolid transitions are consistent with the above conclusions. The results of this study are also consistent with those of a previous study which suggest that the stability of the amorphous calcium phosphate phase is dependent upon the instability of the solution phase with respect to OCP formation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02010771
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Synthese von Zuckerestern der Lysergsäure und 9,10-Dihydrolysergsäure (1979)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 321 (1979), S. 171-174 
    Details
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis of Sugar Esters of Lysergic Acid and 9, 10-Dihydrolysergic Acid
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19793210126
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    The Inversion of the Amino Group in Vinylamine, a Flexible Model TreatmentA preliminary account of this work was given at the meeting of the Swiss Chemical Society in Geneva, October 9, 1976. (1978)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 61 (1978), S. 1418-1426 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Flexible model results for the —NH2 inversion in vinylamine are compared with microwave data published by Lovas et al. [3]. The information available on the spacing of inversion levels is found to be sufficient to rule out a planar equilibrium structure. Shifts of rotational constants upon excitation of the inversion are calculated for two predicted paths of motion derived from PRDDO geometry optimization results obtained by MiiIler & Brown [2]. Partial geometry optimization yields a path inconsistent with experiment but the path obtained from complete optimization produces shifts in excellent agreement with the observed shifts. A potential energy function compatible with experimental data on spacing of inversion levels is calculated from the observed inertia defects. The inversion angle at equilibrium is slightly smaller than the angle predicted from PRDDO calculations, and the barrier to inversion, ΔV = 1.08 ± 0.07 kcal/mol, is approximately half the PRDDO value.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19780610426
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Cinobufaginol Über Krötengifte, 32. Mitteilung31. Mitt. vgl. E. Iseli et al. [1] (1966)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 49 (1966), S. 1243-1246 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Aufklärung der Konstitution von Cinobufaginol (= Substanz G aus Ch'an Su) mit Hilfe der Protonenresonanzspektroskopie.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19660490404
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Die Glykoside der Blätter von Isoplexis isabelliana (WEBB) MASF.Für diese Art des Kanarischen Fingerhuts ist früher [1] [2] die Bezeichnung Digitalis canariensis L., var. isabelliana (WEBB) LINDINGER verwendet worden. Die hier benützte Nomenklatur ist der Arbeit von WERNER [3] entnommen worden.. 3. Mitteilung2. Mitteilung: [2]. (1967)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 50 (1967), S. 1336-1366 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The isolation, characterisation and chemical investigation of the cardiac glycosides of the dried leaves of Isoplexis isabelliana (WEBB) MASF. are described. 7 glucosides B, D, E, J (monoside), K, M, and 1 (monoside) could be obtained in homogenous form, 3 others were mixtures (“A” = A1 + A2, “C” = C1 + C2, and “G” = G + K). The substances B (gluco-evatromonoside), D (cheiroside A), E (digitoxigenin-glucosido-6-deoxyglucoside), J (digitoxigenin glucoside), and M (digitalinum verum) could be identified with known substances. The new glycosides are derived from 3 genins: digitoxigenin, uzarigenin, and xysmalogenin, which are directly bound to one of the following sugars: 6-deoxyglucose, 2-O-acetyl-6-deoxy-D-glucose, 2,6-dideoxy-D-arabinohexose (= D-canarose), and 2,6-dideoxy-D-ribohexose (= D-digitoxose), terminated by a glucose unit. -Canarobiose, a new crystalline disaccharide of D-glucose and D-canarose, has also been obtained. -Apart from these cardiac glycosides 3 C21-steroids have been isolated (in addition to the 2 known genins γ-digiprogenin and purpnigenin), and their structures elucidated. The presence of 2 sapogenins has been detected.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19670500516
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Die Glykoside der Blätter von Isoplexis canariensis (L.) G. DONFür diese Digitalis-Art sind früher andere botanische Bezeichnungen wie Isoplexis canariensis L. und Callianassa canariensis (W. & B.) verwendet worden. Die neue, heir benützte Nomenklatur haben wir aus der Arbeit von Werner [1] übernommen.. 2. Mitteilung1. Mitteilung: P. STUDER et al. [2]. (1967)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 50 (1967), S. 1893-1911 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Aus den getrockneten Blättern von Isoplexis canariensis liess sich nach leichter Abänderung des früher [2] beschriebenen Verfahrens in etwa 1% Ausbeute ein Kristallisat gewinnen, das aus den zwei Glykosidgemischen «A» und «B» im ungefähren Verhältnis 1:4 besteht. Diese unterscheiden sich nur im Zuckerteil - Canarobiose beim Glykosid «A» und Digilanidobiose beim Glykosid «B» - und besitzen die gleichen Aglykone: Uzarigenin, Canarigenin und Xysmalogenin. -2 der 3 Komponenten des Glykosids «A», nämlich Uzarigenin-glucosido-canarosid und Canarigenin-glucosido-canarosid, konnten als einheitliche Kristallisate gewonnen und in die Desglucoprodukte übergeführt werden. Das der 3. Komponente des Glykosids «A» entsprechende Desglucoprodukt, das Xysmalogenin-canarosid, liess sich aus dem Monosidgemisch «e» [2] (das aus «A» durch enzymatische Hydrolyse entsteht) gewinnen. -Das Glykosid «B» konnte bisher noch nicht in seine 3 Komponenten aufgeteilt werden. Aus seinem Monosidgemisch «d» wurden Uzarigenin-digitoxosid sowie Canarigenin-digitoxosid als einheitliche Glykoside und, nach saurer Hydrolyse, Xysmalogenin, das Aglykon des dritten Digitoxosids von «d», gewonnen. - Aus den Mutterlaugen der Glykosidgemische «A» und «B» konnten noch die Substanzen C und «D» erhalten werden. C ist Canarigenin-glucosido-fucosid, während «D» ein Gemisch mehrerer Glykoside darstellt.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19670500724
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    Über neue Bufadienolide aus Ch'an Su. Über Krötengifte, 34. Mitteilung33. Mitt. [1], irrtümlicherweise als 32. Mitt. bezeichnet; 32. Mitt. = [2]. (1969)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 52 (1969), S. 1097-1101 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Two new bufadienolides, isolated from Ch'an Su, are proved to be 19-oxo-cinobufagin (III) and 19-oxo-cinobufotalin (V), respectively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19690520426
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    Dicarbonate und Dicarbamate des DL-Threits und des Erythrits (1966)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 49 (1966), S. 1935-1937 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: DL-Threitol dicarbonate and erythritol dicarbonate were prepared by the reaction of butadiene dioxide (DL and meso) with carbon dioxide. Treated with aqueous ammonia the dicarbonates gave the corresponding dicarbamates.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19660490631
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...