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  • 1
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Journal of the American Chemical Society 79 (1957), S. 4067-4069 
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Journal of the American Chemical Society 79 (1957), S. 3933-3933 
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Monatshefte für Chemie 121 (1990), S. 3-12 
    ISSN: 1434-4475
    Keywords: Cytosine ; Complexes ; Coordination sites ; Cadmium(II)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Es wird über Komplexe von Cadmium(II) mit Cytosin berichtet, die aus wäßrigen oder physiologischen Lösungen erhalten wurden. Die Komplexe wurden mittels spektroskopischer Methoden, Konduktometrie,1H- und13C-NMR-Messungen und mittels Thermogravimetrie charakterisiert.
    Notes: Summary Complexes of cadmium(II) with cytosine obtained from aqueous or physiological solutions at room temperature are reported. The complexes were characterized by spectroscopic, conductometric,1H-NMR, and13C-NMR measurements and also by thermogravimetry.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 0268-2605
    Keywords: diorganotin(IV)chloroamoxicillin ; di-organotin(IV)amoxicillin2 derivatives ; Rutilus rubilio ; genotoxicity ; chromosome aberration ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In Order to test in vivo cytotoxicity of diorganotin(IV)-amoxicillin (amox) derivatives, mitotic chromosomes of Rutilus rubilio (Pisces, Cyprinidae) have been analyzed using two different chromosome-staining techniques.Results gathered after exposure of fish to the free amox · 3H2O, R2SnClamox · 2H2O, and R2Snamox · 2 2H2O (R = methyl, butyl and phenyl; amox- = 6-[D(-)-β-amino-p-hydroxyphenylacetamido]penicillinate) suggest that methyl derivatives seem to exert a lower cytotoxicity than butyl and phenyl ones and that R2Snamox · 2 2H2O deriva-tives are more toxic than R2SnClamox · 2H2O at both 10-5 and 10-7mol dm-3 concentrations.The following structural lesions have been iden-tified by comparative analysis of mitotic chromo-somes from untreated specimens (controls) and specimens treated with diorganotin(IV)-amoxicillin derivatives: (1) differentially stained chromosome areas; (2) granular deeply stained zones along the chromosomal body; (3) arm breakages; and (4) side-arm bridges (pseudochiasmata).
    Additional Material: 6 Ill.
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  • 5
    ISSN: 0268-2605
    Keywords: triorganotin(IV) ; L-homocysteic acid ; infrared ; Mössbauer ; NMR ; sea urchin ; Paracentrotus lividus (Echinodermata) ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Several new triorganotin(IV) derivatives of L-homocysteic acid (L-HCAH) with formula R3Sn(L-HCA) (R=Me, nBu, Ph) have been synthesized. Their solid-state configurations were determined by IR and Mössbauer spectroscopy. The tin(IV) atom is five-coordinated in all the complexes, with the L-homocysteic acid behaving as a monoanionic bidentate ligand coordinating the tin(IV) atom through a chelating or bridging carboxylate group. The sulfonate (SO3-) and NH3+ groups of L-homocysteic acid maintain their free acid configuration and hence do not participate to the coordination of the tin(IV) atom. Coordination hypotheses have been checked through the correlation between the Mössbauer parameter isomer shift, δ, and partial atomic charge on the tin atoms, QSn, performed, for all the new organotin(IV) compounds, on the basis of an equalization procedure applied to idealized trigonal-bipyramidal structures for R3Sn(L-HCA).1H and 13C NMR spectra of the complexes show that pentacoordination of the tin atom, with R groups in the equatorial plane of a trigonal bipyramid, is retained in DMSO solution. The NMR data confirm also that the uncoordinated NH3+ group of the ligand is still present in solution.Results gathered after exposure of two- to four-cell embryos of the sea urchin Paracentrotus lividus (Echinodermata) to the triorganotin(IV) L-homocysteate derivatives as well as to the parent triorganotin(IV) chlorides document cytotoxicity of the complexes, while free L-homocysteic acid exerts no significant toxic activity. The trimethyltin(IV) L-homocysteate derivative seems to exert a lower cytotoxicity than the tributyl- and triphenyl-tin(IV) ones. Different structural lesions have been identified by comparative analysis of mitotic chromosomes from untreated embryos (negative controls) and embryos treated with triorganotin(IV) L-homocysteate derivatives, such as (1) suppression of the stretch among sister chromatids at the beginning of anaphase stage; (2) deeply stained zones mainly located at the telomeric regions of chromosomes; (3) arm breakages; and (4) chromosome bridges among daughter chromosomes at anaphase stage. A colchicine-like effect of triorganotin(IV) L-homocysteate derivatives was observed. © 1997 John Wiley & Sons, Ltd.
    Additional Material: 20 Ill.
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  • 6
    ISSN: 0268-2605
    Keywords: organotin ; antibiotic ; amoxicillin ; structure ; Mössbauer ; infrared ; 1H NMR ; 13C NMR ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Novel di- and tri-organotin(IV) derivatives of amoxicillin (amoxicillin- = Amox- = 6-[D(-)-ß- amino - p - hydroxyphenylacetamido]penicillinate) have been prepared. The isolated compounds showed stoichiometries of the type R2SnClAmox · 2H2O, R3SnClAmoxNa · 2H2O and R2SnAmox2 · 2H2O (R = Me, Bu, Ph). The infrared spectra suggest that Amox-, in both R2SnClAmox · 2H2O and R2SnAmox2 · 2H2O, behaves as a monoanionic bidentáte ligand, coordinating the tin(IV) atom through the ester-type carboxylate, as well as through the lactamic carbonyl.In R3SnClAmoxNa · 2H2O, Amox- coordinates the organotin(IV) moieties through the lactamic carbonyl. In all of the compounds, water molecules are not involved in coordination, as inferred by thermogravimetric (TG) investigation. In both R2SnClAmox · 2H2O and R3SnClAmoxNa · 2H2O, trigonal bipyramidal configurations are proposed in the solid state, on the basis of infrared (IR) and Mössbauer spectroscopy, while in R2SnAmox2 · 2H2O the coordination geometry at tin could be a skew-trapezoidal bipyramid, with two chelating amoxicillin residues which act as bidentate ligands in the trapezoidal plane, and with the organic groups in axial positions. The C—Sn—C angles calculated from the experimental Mössbauer quadrupole splitting predict a bent skeleton in all the R2SnAmox2 2H2O derivatives. 1H and 13C NMR measurements showed that both R2SnClAmox · 2H2O and R2SnAmox2 · 2H2O are stable in DMSO-d6 solutions, maintaining their solid-state configuration, while R3SnClAmoxNa · 2H2O dissociates.Coordination hypotheses have been checked through the correlation between the Mössbauer isomer shift (δ) and the partial atomic charge on tin atoms (QSn) performed, for all the new organotin(IV) compounds, on the basis of an equalization procedure applied to idealized trigonal bipyramidal structures for R2SnClAmox · 2H2O and R3SnClAmoxNa · 2H2O and octahedral trans-R2 for R2SnAmox2 · 2H2O.
    Additional Material: 6 Ill.
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  • 7
    ISSN: 0268-2605
    Keywords: organotin ; antibiotics ; ampicillin ; methicillin ; infrared ; Mössbauer ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Derivatives of D(-)-α-aminobenzylpenicillin (ampicillin) and of 2,6-dimethoxyphenylpenicillin (methicillin) with diorgano- and triorgano-tin(IV) moieties have been synthesized. The stoichiometries of the compounds obtained were of the type R2SnClL·H2O, R3SnClL·H2O [L=ampicillin or methicillin monoanion; R=Me, Bu, Ph] and R2Snampic2· 2H2O (ampic=ampicillin; R=Me, Bu, Ph). For R2SnClL·H2O and R3SnClL Na· - H2O, infrared (IR) data suggest five-coordination around the tin(IV) atom; in R2Snampic2· 2H2O six-coordination is most likely to occur. Thermogravimetric (TG) analysis excludes any involvement in the coordination of tin(IV) by water molecules, in any of the compounds. Trigonal bipyramidal configurations in the solid state are proposed for both R2SnClL·H2O and R3SnClL Na·H2O (L=ampicillin or methicillin) on the basis of the above-mentioned IR and Mössbauer data.As far as R2Snampic2·2H2O compounds are concerned, the coordination geometry at tin could be, as previously reported for analogous R2Snamox2.2H2O derivatives, skew-trapezoidal bipyramidal, the monoanionic bidentate chelating ampicillin residue being in the trapezoidal plane and having bent axial organic groups.Electronegativity equalization procedures have been applied to idealized trigonal bipyramidal structures for R2SnClL·H2O and R3SnClL Na·H2O (L=ampicillin or methicillin) and to octahedral trans-R2for R2Snampic2·2H2O, to estimate the partial atomic charges on the tin atoms, Qsn, which have been correlated with the isomer shift (δ) Mössbauer parameter.
    Additional Material: 7 Ill.
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  • 8
    ISSN: 0268-2605
    Keywords: Organotin ; protoporphyrin IX ; structures ; Mössbauer ; infrared ; UV-visible fluorescence ; nuclear quadrupole splitting ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Protoporphyrin IX (H4PPIX) complexes of diorganotin(IV)chloro moieties with formula (R2SnCl)2H2PPIX (R=Me, Bu and Ph) have been obtained and their solid-state and solution-phase configurations have been studied through spectroscopic investigations.Coordination of the side-chain carboxylates of H4PPIX to R2Sn(IV)Cl moieties, with bridging carboxylate (COO-) has been inferred by comparison of the free and coordinated H4PPIX IR spectra, while the occurrence of a five-coordinated tin(IV) atom in a cis-R2 trigonal bipyramidal structure has been deduced, for all of the synthesized complexes, by rationalization of the nuclear quadrupole splitting parameters, according to the point-charge model formalism. Fanally, the solution-phase spectral features of (R2SnCl)2-H2PPIX are in agreement with the monomeric character of the protoporphyrin IX, under the experimental conditions used.
    Additional Material: 4 Ill.
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  • 9
    ISSN: 0935-6304
    Keywords: Chiral stationary phase ; Carbon dioxide-based mobile phases ; Dynamic chiral chromatography ; Fullerenes ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Fast and efficient separations of chiral stereolabile compounds were obtained at very low temperature on a π-acid chiral stationary phase (R,R-DACH-DNB) using carbon dioxide-based mobile phases containing alcoholic polar modifiers.Furthermore, efficient separations of the newly discovered spherical carbon cluster buckminsterfullerene (C60) and the related higher fullerenes (C70, etc.) have been performed on the same stationary phase using eluents based on either n-hexane or carbon dioxide.
    Additional Material: 6 Ill.
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  • 10
    Publication Date: 2019
    Description: Progress in Physical Geography: Earth and Environment, Ahead of Print. 〈br/〉Urban-geomorphology studies in historical cities provide a significant contribution towards the broad definition of the Anthropocene, perhaps even including its consideration as a new unit of geological time. Specific methodological approaches to recognize and map landforms in urban environments, where human-induced geomorphic processes have often overcome the natural ones, are proposed. This paper reports the results from, and comparison of, studies conducted in coastal historical cities facing the core of the Mediterranean Sea – that is, Genoa, Rome, Naples, Palermo (Italy) and Patras (Greece). Their settlements were facilitated by similar climatic and geographical contexts, with high grounds functional for defence, as well as by the availability of rocks useful as construction materials, which were excavated both in opencast and underground quarries. Over centuries, urbanization has also required the levelling of relief, which was performed by the excavation of heights, filling of depressions and by slope terracing. Consequently, highly modified hydrographic networks, whose streams were dammed, diverted, modified in a culvert or simply buried, characterize the selected cities. Their urban growth, which has been driven by maritime commercial activities, has determined anthropogenic coastal progradation through port and defence or waterfront works. Aggradation of artificial ground has also occurred as a consequence of repeated destruction because of both human and natural events, and subsequent reconstruction even over ruins, buried depressions and shallow cavities. As a result, the selected cities represent anthropogenic landscapes that have been predominately shaped by several human-driven processes, sometimes over centuries. Each landform represents the current result, often from multiple activities with opposing geomorphic effects. Beyond academic progress, we believe that detecting and mapping these landforms and processes should be compulsory, even in risk-assessment urban planning, because of the increase of both hazards and vulnerability as a result of climate-change-induced extreme events and extensive urbanization, respectively.
    Print ISSN: 0309-1333
    Electronic ISSN: 1477-0296
    Topics: Geography
    Published by Sage
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