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  • PANGAEA  (281)
  • Wiley-Blackwell  (60)
  • Frontiers  (2)
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  • 1
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    Long-Term Changes of Particle Flux in the Canary Basin Between 1991 and 2009 and Comparison to Sediment Trap Records Off Mauritania (2020)
    Frontiers
    Details
    Publication Date: 2023-09-19
    Description: Eastern Boundary Upwelling Ecosystems (EBUEs) are associated with high biological productivity, high fish catch and they highly contribute to marine carbon sequestration. Whether coastal upwelling has intensified or weakened under climate change in the past decades is controversially discussed and different approaches (e.g., time-series of chlorophyll, wind, sea surface temperature, modeling experiments) have been considered. We present a record of almost two decades of particle fluxes (1991–2009) from ca. 600 to 3100 m water depth in the Canary Basin at site ESTOC (European Station for Time series in the Ocean Canary Islands; ca. 29°N, 15°30.W, ca. 3600 m water depth), located in the offshore transition zone of the northern Canary Current-EBUE. We compare these flux records with those measured at a mesotrophic sediment trap site further south off Cape Blanc (Mauritania, ca. 21°N). The deep ocean fluxes at ESTOC in ca. 3 km recorded the evolution of the coastal Cape Ghir filament (30–32°N, 10–12°W) due to lateral advection of particles, whereas the upper water column sediment traps in ca. 1 km reflected the oligotrophic conditions in the overlying waters of ESTOC. We observed an increased emphasis in spring-time fluxes since 2005, associated with a change in particle composition, while satellite chlorophyll biomass did not show this pattern. Due to its northern location in the CC-EBUEs, spring biogenic fluxes at ESTOC provide a better relationship to the forcing of the North Atlantic Oscillation than those recorded further south off Cape Blanc. Off Cape Blanc, deep fluxes showed the best overlap with the deep ESTOC fluxes during the spring season before 2005. On the long-term, both chlorophyll and particle fluxes showed an increasing trend at ESTOC which was not observed further south at the mesotrophic Cape Blanc site. This might indicate that, depending on their location along the NW African margin, coastal upwelling systems react differently to global change.
    Type: Article , PeerReviewed
    Format: text
    Format: text
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  • 2
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    A Novel Measurement-Based Model for Calculating Diffusive Fluxes Across Substrate-Water Interfaces of Marine Aggregates, Sediments and Biofilms (2021)
    Frontiers
    Details
    Publication Date: 2024-02-07
    Description: Our understanding of the small-scale processes that drive global biogeochemical cycles and the Earth’s climate is dependent on accurate estimations of interfacial diffusive fluxes to and from biologically-active substrates in aquatic environments. In this study, we present a novel model approach for accurate calculations of diffusive fluxes of dissolved gases, nutrients, and solutes from concentration profiles measured across the substrate-water interfaces using microsensors. The model offers a robust computational scheme for automatized determination of the interface position and enables precise calculations of the interfacial diffusive fluxes simultaneously. In contrast to other methods, the new approach is not restricted to any particular substrate geometry, does not require a priori determination of the interface position for the flux calculation, and, thus, reduces the uncertainties in calculated fluxes arising from partly subjective identification of the interface position. In addition, it is robust when applied to measured profiles containing scattered data points and insensitive to reasonable decreases of the spatial resolution of the data points. The latter feature allows for significantly reducing measurement time which is a crucial factor for in situ experiments.
    Type: Article , PeerReviewed , info:eu-repo/semantics/article
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  • 3
    Electronic Resource
    Electronic Resource
    Cytotoxische Verbindungen, V. Bis-[2-chlor-äthyl]-[2-acyl-vinyl]-amine (1969)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 102 (1969), S. 3139-3147 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Aus Bis-[2-chlor-äthyl]-amin (HN-Lost) und Derivaten aromatischer β-Hydroxy-vinylketone resultieren Bis-[2-chlor-äthyl]-[2-acyl-vinyl]-amine 6. Das Reaktionsverhalten dieser vinylogen Stickstofflost-Amide wird untersucht und der Einfluß von Substituenten auf ihre Stabilität im schwach sauren Medium diskutiert.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19691020934
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  • 4
    Electronic Resource
    Electronic Resource
    Vinyloge Acylverbindungen, VII. Synthese und reaktives Verhalten vinyloger N-Acyl-pyridiniumsalze (1970)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 103 (1970), S. 3470-3488 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Vinylogous Acyl Compounds, VII Synthesis and Reactive Behaviour of Vinylogous N-Acylpyridinium SaltsAddition of mineral acid salts of pyridines to propargyl aldehyde yields N-(2-formylvinyl)-pyridinium salts 7. Related N-(2-acylvinyl)-pyridinium salts 10-13 and 15 result from the reaction of β-chlorovinyl ketones with pyridine or substituted pyridines. Compounds of this type represent vinylogous N-acylpyridinium salts and are accessible to facile nucleophilic replacement of the pyridine residue: with primary and secondary aromatic amines the reaction gives N-(2-acylvinyl)-amines 21; with hydrazines, pyrazoles 22; with ammonium acetate/acetic acid, substituted pyridines 23 and bis(2-acylvinyl)-amines 24; with sodium sulfide, bis(2-acylvinyl)-sulfides 26 and 28; with carboxylates, 2-acylvinyl esters 27; and with sodium azide, 2-acylvinyl azides 29 and 30.
    Notes: Die Addition mineralsaurer Pyridinsalze an Propargylaldehyd führt zu N-[2-Formyl-vinyl]-pyridiniumsalzen 7. Entsprechende N-[2-Acyl-vinyl]-pyridiniumsalze 10-13 sowie 15 resultieren aus β-Chlor-vinylketonen und Pyridin bzw. substituierten Pyridinen. Verbindungen dieses Typs repräsentieren vinyloge N-Acyl-pyridiniumsalze und zeichnen sich durch den leichten nucleophilen Ersatz des Pyridinrestes aus: Mit primären und sekundären aromatischen Aminen reagieren sie zu N-[2-Acyl-vinyl]-aminen 21, mit Hydrazinen zu Pyrazolen 22. mit Ammoniumacetat/Eisessig zu substituierten Pyridinen 23 und Bis-[2-acyl-vinyl]-aminen 24, mit Natriumsulfid zu Bis-[2-acyl-vinyl]-sulfiden 26 bzw. 28, mit Carboxylaten zu [2-Acyl-vinyl]-estern 27 und mit Natriumazid zu [2-Acyl-vinyl]-aziden 29 bzw. 30.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19701031113
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  • 5
    Electronic Resource
    Electronic Resource
    Vinyloge Acylverbindungen, IX. Zur Hydrolyse vinyloger Carbonamidiumsalze (1971)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 104 (1971), S. 210-219 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Vinylogous Acyl Compounds, IX. Hydrolysis of Vinylogous Carbonamidium SaltsThe hydrolysis of vinylogous carbonamidium salts 10 in aqueous sodium hydrogen carbonate solution does not lead - as hitherto supposed - to meso-(2-acylvinyl)acylacetaldehydes 8, but to bis(2-acylvinyl)ethers 11. The structure of these compounds results from n. m. r. and i. r. spectra and is confirmed by independent synthesis.
    Notes: Die Hydrolyse vinyloger Carbonamidiumsalze 10 in wäßriger Natriumhydrogencarbonat-Lösung führt nicht - wie bisher angenommen - zu meso-[2-Acyl-vinyl]-acylacetaldehyden 8, sondern zu Bis-[2-acyl-vinyl]-äthern 11. Die Strukturzuordnung dieser Verbindungen gründet sich auf NMR- und IR-spektroskopische Befunde sowie auf eine unabhängige synthese.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19711040126
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  • 6
    Electronic Resource
    Electronic Resource
    Pyryliumverbindungen, VIII. Ketovinyl-enamine aus Enaminen und β-Chlor-vinylketonen (1969)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 102 (1969), S. 575-589 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Enamine (1) reagieren mit β-Chlor-vinylketonen (4) zu doppelt ungesättigten 1.5-Aminoketonen, den sogenannten Ketovinyl-enaminen (6-39). Die Strukturzuordnung dieser Verbindungen gründet sich auf die positive Solvatochromie, die Addition elektrophiler Agentien (zu 45-49) und die Cyclodesaminierung zu Pyryliumsalzen.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19691020225
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  • 7
    Electronic Resource
    Electronic Resource
    Vinyloge Acylverbindungen, III. Synthese und Reaktionen quartärer N-[β-Formyl-vinyl]-ammoniumsalze (1969)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 102 (1969), S. 2609-2620 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Propargylaldehyd reagiert mit mineralsauren Salzen tertiärer aliphatischer Amine zu quartären N-[β-Formyl-vinyl]-ammoniumsalzen 4. Alkalien bewirken Hydrolyse von 4 zu Salzen des Malondialdehyds, unter schärferen Bedingungen auch Fragmentierung. Primäre aromatische Amine setzen sich mit 4 in neutraler Lösung zu Anilen 6, in saurer Lösung zu Malondialdehyd-dianilsalzen 7, sekundäre Amine zu entsprechenden vinylogen Amidiniumsalzen 9 um. 1.2-Dianilino-äthan reagiert mit 4 in Abhängigkeit vom Medium zu Imidazolidin-Derivaten 11 oder zum Dihydro-1.4-diazepiniumsalz 12. Während die aus 4 resultierenden Arylhydrazone 15 einem Ringschluß zu 1-substituierten Pyrazolen 16 widerstehen, bilden sich letztere aus den Dianilen 8. Mit Barbitur- und 2-Thiobarbitursäure entstehen Farbstoffe vom Oxonol-Typ 18.
    Additional Material: 8 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19691020816
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  • 8
    Electronic Resource
    Electronic Resource
    Vinyloge Acylverbindungen, VIII. Ringöffnungsreaktionen vinyloger N-Acyl-pyridiniumsalze (1970)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 103 (1970), S. 3489-3501 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Vinylogous Acyl Compounds, VIII Ring-Opening Reactions of Vinylogous N-Acylpyridinium SaltsVinylogous N-acylpyridinium salts 2 undergo ring cleavage by alkali to azaoxonol dyes 8, which on treatment with acids reversibly release N-acylvinylated 5-aminopenta-2,4-dienals 9. Related merocyanines 11 are obtained from (pyridiniomethylene)benzocyclenone salts 10. Quarternary salts 12 derived from 3-picoline are cleaved at C-2 of the ring. Primary and secondary aromatic amines react with 9 to give pentamethincyanines 16. Treatment of 2 with aliphatic amines results in ring opening and formation of unstable azamerocyanines 22, which in part can be isolated as salts 23.  -  The spectral behaviour of the ring-fission products obtained are discussed.
    Notes: Vinyloge N-Acyl-pyridiniumsalze 2 erfahren bei Einwirkung von Alkali eine Ringauf-spaltung zu Azaoxonol-Farbstoffen 8, die mit Säuren reversibel N-acylvinylierte 5-Amino-pentadien-(2.4)-ale 9 freigeben. Entsprechende Merocyanine 11 resultieren aus [Pyridinio-methylen]-benzocyclenonsalzen 10. Vom 3-Methyl-pyridin abgeleitete Quartärsalze 12 werden am Ringatom C-2 gespalten. Primäre und sekundäre aromatische Amine überführen 9 in Pentamethincyanine 16. Aliphatische Amine öffnen 2 zu instabilen Azamerocyaninen 22, die z. T. in Form ihrer Salze 23 gefaßt werden können. - Das Spektralverhalten der erhaltenen Ringöffnungsprodukte wird diskutiert.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19701031114
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  • 9
    Electronic Resource
    Electronic Resource
    Pyryliumverbindungen, IX. Pyryliumsalze aus Ketovinyl-enaminen (1969)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 102 (1969), S. 590-602 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Es wird eine neue Synthese von Pyryliumsalzen (17-28, 32-34 und weitere) durch Cyclodesaminierung zweifach ungesättigter 1.5-Aminoketone (Ketovinyl-enamine) (5-16, 29-31 und weitere), die durch Umsetzung von β-Chlor-vinylketonen mit Enaminen leicht erhältlich sind, beschrieben. Ausgehend von ketovinylierten Aldehyd-Enaminen sind erstmals 2.5-disubstituierte Pyryliumsalze zugänglich; aus ketovinylierten Ringketon-Enaminen resultieren Pyryliumsysteme mit angegliedertem Carbocyclus.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19691020226
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  • 10
    Electronic Resource
    Electronic Resource
    Pyryliumverbindungen, XI. Die Kondensation von Ketonen mit β-Diketonen zu Pyryliumsalzen (1969)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 102 (1969), S. 1214-1223 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Enolisierbare β-Diketone reagieren in Gegenwart starker Säuren mit α-methylenaktiven Ketonen zu mehrfach substituierten, mono- und polycyclischen Pyryliumsalzen. Dieses Syntheseprinzip wurde bezüglich seiner Leistungsfähigkeit und Grenzen untersucht. Es eignet sich mit besonderem Vorteil zur Darstellung von Indeno[2.1-b]pyryliumsalzen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19691020414
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