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  • 1
    Electronic Resource
    Electronic Resource
    Periodic shedding and replacement of venomous caudal spines, with special reference to South American freshwater stingrays, Potamotrygon spp. (1988)
    Springer
    Environmental biology of fishes 23 (1988), S. 299-314 
    Details
    ISSN: 1573-5133
    Keywords: Batoidea ; Chondrichthyes ; Elasmobranchii ; Amazon ; Magdalena ; Maracaibo ; Orinoco ; Paraná-Paraguay
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Synopsis The number of venomous caudal spines and their length and position relative to one another were determined in seven species of South American freshwater rays (Potamotrygonidae) and eight marine or euryhaline species of four families from the Caribbean Coast of South and Central America. Most species have two visible spines at certain stages in the shedding-replacement cycle and only one visible spine at other stages (following shedding). If we include the embryological beginnings of the spines before they erupt and become visible, the spine counts of most rays are actually 2 rather than 1 or 2. Since most species apparently follow this pattern, spine counts are of little use in distinguishing between species except in the relatively few that may have only one, or no spines. Eight captive Potamotrygon specimens maintained in simulated tropical temperature conditions over 12 months showed periodic shedding and replacement of spines. The molts were biannual for a given ray but annual for a given spine. They alternated between two spine loci and their cycles were approximately six months out of phase with each other. Recent studies on Dasyatis sabina by others report only one molt per year, with replacement spines forming always posterior to the primary spine rather than alternating between posterior and anterior. Supernumerary spines (counts of more than two, up to five) are also discussed, as are counts of one and zero.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00005241
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  • 2
    Electronic Resource
    Electronic Resource
    Reproduction and development of the South American freshwater stingrays,Potamotrygon circularis and P. motoro (1983)
    Springer
    Environmental biology of fishes 9 (1983), S. 3-24 
    Details
    ISSN: 1573-5133
    Keywords: Amazonia ; Batoidea ; Brazil ; Captive breeding ; Chondrichthyes ; Colombia ; Elasmobranchii ; Freshwater adaptation ; Growth rate ; Potamotrygonidae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Synopsis Observations of reproductive features and body measurements were made on wild-caught, freshwater stingrays, Potamotrygon circularis and P. motoro, from the Amazon drainage of western Brazil and southern Colombia. Further observations were made in Detroit's Belle Isle Aquarium on a captive pair of P. motoro and their descendants, which constitute the first known captive breeding colony of potamotrygonids. The gross structure and function of female and male reproductive systems are described. There is no obvious difference between those of the two species. They are aplacentally viviparous, the young being nourished in advanced stages by uterine milk secreted by trophonemata. Size at onset and completion of sexual maturation, breeding season and behavior, gestation period, litter size and sex ratios are discussed. Up to 21 proportional measurements were made on several fetal and postnatal stages of both species. Several proportional changes occur in very early fetal life, but most body proportions undergo only minor changes from advanced fetal through adult stages. A growth curve is proposed for P. motoro based on observations of the captive colony.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00001055
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  • 3
    Electronic Resource
    Electronic Resource
    The bull shark (Carcharhinus leucas) and largetooth sash (Pristis perotteti) in Lake Bayano, a tropical man-made impoundment in Panama (1982)
    Springer
    Environmental biology of fishes 7 (1982), S. 341-347 
    Details
    ISSN: 1573-5133
    Keywords: Elasmobranchii ; Euryhalinity ; Freshwater adaptation ; Dam lake ; Osmoregulation ; Central America
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Synopsis The Río Bayano in eastern Panama is one of many tropical rivers in which bull sharks (Carcharhinus leucas) and largetooth sawfish (Pristis perotteti) have been known to occur. Since both species can osmoregulate in fresh water throughout life, theoretically, both could survive in landlocked situations for many years.P. perotteti reproduces in fresh water, butC. leucas ordinarily does not, so only the former would appear to have the potential for establishing a breeding stock in such a landlocked freshwater body. The damming of the Rio Bayano and the creation of a large impoundment in 1976 provides a test of the ability of members of both species trapped there to survive and to establish breeding stocks. In 1980 and 1981 three mature femaleC. leucas were found dead in Lake Bayano and three sub-adult femaleP. perotteti were taken by trammel net. These events confirm the ability of both to survive in fresh water for long periods, but the establishment of breeding stocks appears doubtful and the question may not be answered for many years.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00005568
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  • 4
    Electronic Resource
    Electronic Resource
    Untersuchungen an Systemen aus Salzen und gemischten Lösungsmitteln. XXXIV. 27Al- und 1H-NMR-spektroskopische Untersuchungen an Lösungen des Systems AlCl3-Wasser-N,N-Dimethyl- formamid (1988)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 558 (1988), S. 231-239 
    Details
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Studies on Systems of Salts and Mixed Solvents. XXXIV. 27Al and 1H N.M.R. Spectroscopic Investigations of AlCl3-Water-N,N-Dimethylformamide SolutionsAl3+ ions exist in aqueous solutions as well as in DMF solutions in a sixfold coordination; the coordination of DMF exclusively occurs via the oxygen atom. Because of the small shift difference between the pure aqueous and the pure DMF solution at the 27Al n.m.r. spectra no separated signals were found corresponding to the species with mixed coordination. From the changes of the Al chemical shifts and of the linewidths in dependence of the solvent composition a selective solvation process is suggested. At the 1H n.m.r. spectra for the formyl and methyl protons of DMF separated signals appear for the molecules of the first coordination sphere and of the bulk, respectively. From this the number of directly coordinated DMF molecules can be determined. Up to a DMF content of about x = 0.45 DMF is preferentially coordinated, after that a change of selectivity takes place and accordingly water is preferred at the first coordination sphere.
    Notes: Al3+-Ionen werden sowohl in wäßrigen als auch in DMF-Lösungen sechsfach koordiniert, die Koordination des DMF erfolgt über Sauerstoff. Wegen der geringen Verschiebungsdifferenz zwischen der reinen wäßrigen und der reinen DMF-Lösung treten in den 27Al-NMR-Spektren mit gemischtem Lösungsmittel keine getrennten Signale für gemischt-koordinierte Spezies auf. Aus den Änderungen der Al-chemischen Verschiebung und der Halbwertsbreite der Signale in Abhängigkeit von der Lösungsmittelzusammensetzung werden Hinweise auf eine selektive Solvatation erhalten. In den 1H-NMR-Spektren erscheinen für die Formyl- und Methylprotonen des DMF getrennte Signale für die Moleküle in der ersten Koordinationssphäre und die des restlichen Lösungsmittels. Daraus läßt sich die Anzahl der direkt koordinierten DMF-Moleküle ermitteln. Bis zu einem DMF-Gehalt von x s≈ 0,45 wird bevorzugt DMF koordiniert, danach tritt ein Selektivitätswechsel auf, so daß bevorzugt Wasser koordiniert wird.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19885580124
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  • 5
    Electronic Resource
    Electronic Resource
    NMR-spektroskopische Untersuchungen an Fluoro-diaza-diphosphetidinen und Fluoro-λ5-monophosphazenen (1987)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 544 (1987), S. 225-231 
    Details
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: N.M.R. Investigations of Fluorodiazadiphosphetidines and Fluoro-λ5-monophosphazenesThe 19F and 31P n.m.r. data of 37 fluorodiazadiphosphetidines [RR′PF—NC6H4X]2, and 62 fluoro-λ5-monophosphazenes, RR′PF=NC6H4X, are submitted. In the case of tetrafluorodiazadiphosphetidines, [RPF2—NC6H4X]2, an intramolecular exchange of the fluorine atoms at phosphorus has to be concluded from the n.m.r. data. The influence of the substituents R and X on the n.m.r. parameters is discussed using simple models of molecular structure.
    Notes: Es werden die 19F- und 31P-NMR-Daten von 37 Fluorodiazadiphosphetidinen, [RR′PF—NC6H4X]2, und 62 Fluoro-λ5-monophosphazenen, RR′PF=NC6H4X, mitgeteilt. Aus ihnen muß für die Tetrafluorodiazadiphosphetidine, [RPF2—NC6H4X]2, auf einen intramolekularen Positionswechsel der Fluoratome am Phosphor geschlossen werden. Der Einfluß der Substituenten R und X auf die NMR-Parameter wird anhand einfacher Modelle der Molekülstruktur diskutiert.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19875440124
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  • 6
    Electronic Resource
    Electronic Resource
    Untersuchungen an Systemen aus Salzen und gemischten Lösungsmitteln. XXXVI. 1H- und 27AI-NMR-Untersuchungen des Solvatationsverhaltens in konzentrierten Lösungen des Systems AICI3-Wasser-Alkohol (1988)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 566 (1988), S. 169-179 
    Details
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Studies on Systems of Salts and Mixed Solvents. XXXVI. 1H and 27Al N.M.R. Spectroscopic Investigations of the Solvation Behaviour in Concentrated AlCl3-Water-Alcohol Solutions1H. n.m.r. spectroscopic investigations in dependence on the solvent composition and the salt concentration are useful for the characterization of solvation processes in concentrated solutions of AlCl3-water-methanol, -ethanol, -ethylene glycol, and -diethylene glycol. In these systems water is preferentially coordinated at the first coordination sphere of the Al3+ ion within the whole region of the solvent composition.The nature of the solvation species has been investigated using 27Al n.m.r. spectroscopy. In order to reduce the „solid-type“ interactions in the concentrated solutions the Magic Angle Spinning method (MAS) was used. Particularly water-poor and water-free solutions produce structured 27Al-Mas-signals. For the system AlCl3-water-ethanol an identification of solvation species is given.
    Notes: Durch 1H-NMR-Untersuchungen in Abhängigkeit von der Lösungsmittel-zusammensetzung und der Salzkonzentration werden Solvatationsprozesse in konzentrierten Lösungen von AlCl3-Wasser-Methanol, -Ethanol, -Ethylenglycol und -Diethylenglycol näher charakterisiert. Es wird jeweils eine bevorzugte Solvatation des Al3+-Ions durch Wasser über den gesamten Zusammensetzungsbereich der Lösungsmittel festgestellt.27Al-NMR-Untersuchungen dienen zur Identifizierung von Solvatationsspezies. Zur Reduzierung der festkörperähnlichen Wechselwirkungen in den konzentrierten Elektrolytlösungen wurde die Methode der schnellen Probenrotation um den „magischen“ Winkel (MAS) eingesetzt. Insbesondere wasserarme und wasserfreie Lösungen der Systeme zeigen strukturierte 27Al-MAS-Signale. Im System AlCl3-Wasser-Ethanol wird eine Identifizierung von Solvatationsspezies vorgenommen.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19885660122
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  • 7
    Electronic Resource
    Electronic Resource
    N. Methyl-N-diäthoxyphosphorylamido-Derivate des Hexachlorocyclotriphosphazatriens. I. Die Reaktion von Hexachlorocyclotriphosphazatrien mit dem Natriumsalz des N-Methylamidophosphorsäurediäthylesters (1975)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 415 (1975), S. 51-56 
    Details
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: N-Methyl-N-Diethoxyphosphorylamido Derivatives of Hexachlorocyclotriphosphazatriene. I. The Reaction of Hexachlorocyclotriphosphazatriene with Sodium N-Methylamidophosphoric Acid Diethyl Ester.The reaction of hexachlorocyclotriphosphazatriene with the sodium salt of 0, 0-diethyl-N-methylamido-phosphate in the molar ratios 1:1, 1:2, and 1:3 gives a mixture of partially substituted compounds. The N-methyl-N-diethoxyphosphorylamidoderivatives, N3P3Cl6-n[NCH3P(O)(OC2H5)]n (n = 1, 2, 3) were isolated in a pure form by preparative column chromatography. Compounds with a higher degree of substitution are not formed. The compounds are characterized by their molecular weights, elementary analysis, and TLC-Rf values.
    Notes: Die Reaktion von Hexachlorocyclotriphosphazatrien mit dem Natriumsalz des N-Methylamidophosphorsäurediäthylesters führt bei Raumtemperatur in den Molverhältnissen 1:1, 1:2 und 1:3 zu einem Gemisch partiell substituierter Verbindungen. Mit Hilfe der präparativen Säulenchromatographie konnten die N-Methyl-N-diäthoxyphosphorylamido-Derivate, N3P3Cl6-n[NCH3P(O)(OC2H5)2]n (n = 1, 2, 3); in reiner Form isoliert werden. Verbindungen höheren Substitutionsgrades wurden nicht erhalten. Die Verbindungen wurden durch ihre Molmassen, Elementaranalysen und die dünnschichtchromatographischen Rf-Werte charakterisiert und gesichert.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19754150108
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  • 8
    Electronic Resource
    Electronic Resource
    N-Methyl-N-Diäthoxyphosphorylamideo-Dervite des Hexachlorocyclotriphosphazatriens. II. Die Ammonolyse der N-Methyl-N-deäthoxyphosphorylamido-chlorcocyclotriphosphazatriene (1975)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 416 (1975), S. 169-173 
    Details
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: N-Methyl-N-Diethoxyphosphorylamido Derivatives of Hexachlorocyclotriphosphazatriene. II. Ammonoloyses of N-Methyl-N-Diethoxyphosphorylamido-ChlorocyclotriphosphazatrienesMonokis-[N-methyl-N-diethroxyphosphorylamido]-pentachloro-cyclotriphospha-zatriene and 2, 4-bis-[N-methyl-N-diethoxyphosphorylamido]-2, 4, 6, 6-tetrachloro-cyclotriphosphazatriene react with gaseous ammonia at room temperature to the corresponding diamino compounds, N3P3CL4-n[NCH3P(O)(OC2H5)2]n(NH2)2, (n = 1, 2). Total Exchange of the chlorine in the N-Methyl-Ndiethoxyphosphorylamido-derivatives, N3P3CL6-n[NCH3P(O)(OC2H5)2]n, (n = a, 2, 3), takes place during the reaction with liquid ammonia. Aminophosphazenes of the type N3P3[NCH3P(O)(OC2H5)2]n(NH2)6-n, (n = 1, 2, 3), are formed. The described aminocyclotriphosphazatrienes are characterized by their melting points, elementary analyses, molecular weights and the TLC-Rf-values.
    Notes: Monokis-[N-methyl-N-diäthoxyphorylamido]-pentachloro-cyclotriphosphazatrien und 2, 4-Bis-[N-methyl-N-diäthoxyphosphorylamido]-2,4,6,6-tetrachlorocyclotriphosphazatrien reagieren mit gasförmigem Ammoniak bei Raumtemperatur zu den entsprechenden diaminoverbindungen, N3P3CL4-n[NCH3P(O)(OC2H5)2]n(NH2)2, (n = 1, 2). Vollständiger Austausch des Chlors in den N-Methyl-N-diäthoxyphosphorylamido-Derivaten, S3P3CL6-n[NCH3P(O). (OC2H5)2]n, (n = 1, 2, 3). findet bei der Umsetzung mit flüssigem ammonial Statt. Es werden dabei Aminocyclophosphazene des Typs N3P[NCH33P(O)(OC2H5)2]n(NH2)6-n, (n = 1. 2. 3) gebildet, Die beschriebenen Aminocyclophosphazatriene werden durch ihre Schmelzpunkte, Elementaranalysen, Molmassen und die dünnschichtchromatographischen Rf-Werte charakterisiert.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19754160208
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  • 9
    Electronic Resource
    Electronic Resource
    Untersuchungen zur Temperaturabhängigkeit der 31P-chemischen Verschiebung in Trialkoxyphosphazen-N-phosphoryldialkylesternProfessor Hans-Albert Lehmann zum 60. Geburtstage am 1. Mai 1979 gewidmet (1979)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 451 (1979), S. 5-11 
    Details
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Temperature Dependence Investigations of 31P Chemical Shifts of Trialkoxyphosphazene N-phosphoryldialkylestersThe 31P NMR spectra of a series of trialkoxyphosphazene-N-phosphoryldialkylesters, (RO)3P=N—P(O)(OR′)2, where R = R′ = Et; R = Et, R′ = Bu; R = Bu, R′ = Et; R = R′ = Bu; and R = R = R′ = Hex respectively, and of trichlorophosphazene-N-phosphoryldichloride were investigated at various temperatures. The temperature dependence of chemical shift of phosphorus belonging to the phosphazene group is multiplicately larger than that of phosphorus belonging to the phosphoryl group. This fact also could be confirmed for other simple phosphazene and phosphoryl compounds. As discussed this different temperature dependence of 31P chemical shift is not a consequence of the medium but of the molecular structure.
    Notes: Für eine Reihe von Trialkoxyphosphazen-N-phosphoryldialkylestern, (PO)3P=N—P(O)(OR′)2, wobei R = R′ = Et; R = Et, R′ = Bu; R = Bu, R′ = Et; R = R′ = Bu bzw. R = R′ = Hex waren, sowie für Trichlorphosphazen-N-phosphoryldichlorid wurden jeweils 31P-NMR-Spektren bei verschiedenen Temperaturen aufgenommen. Es zeigte sich, daß die Temperaturabhängigkeit der chemischen Verschiebung für den Phosphor der Phosphazen-Gruppierung um ein mehrfaches größer ist als die für den Phosphor der Phosphoryl-Gruppierung. Dies konnte auch allgemein für andere einfache Phosphazen- und Phosphoryl-Verbindungen bestätigt werden. Es wird diskutiert. daß diese unterschiedliche Temperaturabhängigkeit der 31P-chemischen Verschiebung nicht auf Medieneinflüsse, sondern auf die molekulare Struktur zurückzuführen ist.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19794510102
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  • 10
    Electronic Resource
    Electronic Resource
    NMR-spektroskopische Untersuchungen an exocyclisch 15N-markierten Amidochlorocyclotriphosphazenen (1982)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 489 (1982), S. 131-138 
    Details
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: NMR Spectroscopic Studies of Exocyclic 15N Labelled AmidochlorocyclotriphosphazenesSome exocyclic 15N labelled monoamidopentachlorocyclotriphosphazenes, N3P3Cl5X, and diamidotetrachlorocyclotriphosphazenes, N3P3Cl4X2, where X = 15NH2, 15NHMe, 15NMe2, or 15NHPh, were prepared, and the 31P- and 15N-NMR spectra were recorded. The chemical shift values δP and δN and the coupling constants 1JPN and 3JPN are discussed.
    Notes: Einige exocyclisch 15N-markierte Monoamidopentachlorocyclotriphosphazene, N3P3Cl5X, und Diamidotetrachlorocyclotriphosphazene, N3P3Cl4X2, wobei X = 15NH2, 15NHMe, 15NMe2 oder 15NHPh ist, wurden dargestellt und die 31P- und 15N-NMR-Spektren aufgenommen. Die chemischen Verschiebungen δP und δN und die Kopplungskonstanten 1JPN und 3JPN werden diskutiert.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19824890115
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