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  • Wiley  (35)
  • Wiley-Blackwell  (27)
  • Cell Press  (5)
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  • 1986  (72)
  • 1
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Metabolites of Microorganisms. Sulfur-Containing Ansa Compounds of the Naphthomycin TypeFrom a strain of Streptomyces (Tü 2357) in addition to naphthomycin A, 4 new yellow pigments were isolated and their structures determined by spectroscopic comparison with naphthomycin A. Whereas the naphthomycins D and E are simple derivatives of naphthomycin A, having OH and H, respectively, instead of Cl, the naphthomycins F and G contain an N-acetylcysteine residue linked to the aromatic moiety by a thioether group. Degradations with O3 yielded identical products from the naphthomycins A, D, F, and G, showing coincident configurations in parts of the molecules. Naphthomycin F shows some biological activity against gram-positive bacteria and fungi, although much weaker than naphthomycin A. The naphthomycins D, E, and G are inactive against microorganisms.
    Additional Material: 4 Tab.
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  • 2
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 119 (1986), S. 872-877 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Seven- (N2O2Si3) and Eight-membered (N2O2Si4) Rings from a (Hydroxysilyl)hydrazine and 1-Amino-3-fluorosiloxanesHalogeno-functional siloxanes [(Me3C)2SiCl—O—SiHalR2, Hal = F, R = CMe3 (2), Hal = Cl, R = Ph (3)] are obtained in the reaction of dihalogenosilanes with (Me3C)2Si(Cl)OLi (1a). (Me3C)2Si(Cl)OH reacts smoothly with ammonia to form the aminosilanol (Me3C)2Si(NH2)OH (4). With fluorosilanes its lithium salt 4a yields the amino- and fluoro-functional siloxanes 5 - 8 [(Me3C)2Si(NH2) —O—SiFRR′, R = R′ = Me (5), R = R′ = CMe3 (6), R = F, R′ = CMe3 (7), R = F, R′ = N(SiMe3)2 (8)]. Primary amines react with 1 by intermolecular HCl elimination to give the 1-chloro-3-hydroxysiloxane 9, hydrazine reacts to form the N,N′-bis(hydroxysilyl)hydrazine 10, methylhydrazine to yield the N-(hydroxysilyl)-N-methylhydrazine 11, and N,N′-dimethylhydrazine to give 9. The reaction of the dilithium salt 10a with F3SiN(SiMe3)2 leads to the formation of the seven-membered N2O2Si3 ring 12. The 1,5,3,7,2,4,6,8-dioxadiazatetrasilocanes 13 and 14 are obtained by LiF elimination from lithiated 5 and 7, respectively.
    Notes: Halogenfunktionelle Siloxane [(Me3C)2SiCl - O—SiHalR2, Hal = F, R = CMe3 (2), Hal = Cl, R = Ph (3)] werden durch Reaktion der Dihalogensilane mit (Me3C)2Si(Cl)OLi (1a) erhalten. Mit Ammoniak reagiert (Me3C)2Si(Cl)OH (1) glatt unter Bildung des Aminosilanols (Me3C)2Si(NH2)OH (4), dessen Lithiumsalz 4a mit Fluorsilanen die amino- und fluorfunktionellen Siloxane 5 - 8 [(Me3C)2Si(NH2) - O—SiFRR′, R = R′ = Me (5), R = R′ = CMe3 (6), R = F, R′ = CMe3 (7), R = F, R′ = N(SiMe3)2 (8)] bildet. Primäre Amine reagieren mit 1 unter intermolekularer HCl-Abspaltung zum 1-Chlor-3-hydroxysiloxan 9, Hydrazin zum N,N′-Bis(hydroxysilyl)hydrazin 10, Methylhydrazin zum N-(Hydroxysilyl)-N′-methyl-hydrazin 11 und N,N′-Dimethylhydrazin zu 9. Die Reaktion des Dilithiumsalzes 10a mit F3SiN(SiMe3)2 führt zur Bildung des siebengliedrigen N2O2Si3-Ringes 12. Durch LiF-Eliminierung aus lithiiertem 5 und 7 entstehen die 1,5,3,7,2,4,6,8-Dioxadiazatetrasilocane 13 und 14.
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  • 3
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Preparation and Structure of New Six-membered Metallaheterocycles - Insertion of Platinum in Selenium-Nitrogen and Sulfur-Nitrogen BondsThe reaction of 1,2,5-selenadiazoles 2 and 4 and the bicycle 6 with (η2-ethene)bis(triphenylphosphane)platinum(0) leads to the cyclic coordination compounds (Ph3P)2PtSeN2(CR)2 (R = CN, 3; R = OCH2CF3, 5) and the bicycle (Ph3P)2PtC4Cl2N4S3 (7). The structure of 3 was determined by an X-ray structure analysis.
    Notes: Die Reaktion der 1,2,5-Selenadiazole 2 und 4 sowie des Bicyclus 6 mit (η2-Ethen)bis(triphenylphosphan)platin(0) führt zu den cyclischen Koordinationsverbindungen (Ph3P)2-PtSeN2(CR)2 (R = CN, 3; R = OCH2CF3, 5) und dem Bicyclus (Ph3P)2PtC4Cl2N4S3 (7). Von 3 wurde eine Röntgenstrukturanalyse angefertigt, die das Vorliegen eines sechsgliedrigen Ringes bestätigt.
    Additional Material: 1 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 189 (1986), S. 145-156 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The structural organization of the compound eye of the largest known isopod, Bathynomus giganteus, is described from four specimens maintained in the laboratory for as long as two months. Living specimens have not previously been available for study. The two triangular compounds eyes measure about 18 mm on the dorsal edge and are separated by an interocular distance of 25 mm. They face forward and slightly downward and may have significant overlap in visual fields. Each eye contains about 3,500 ommatidia in animals of body lengths from 22.5 cm to 37.5 cm. The packing of ommatidia is not uniform across the retina, but is nearly hexagonal in the dorsal central region and nearly square in the ventral and lateral periphery.The dioptric elements in each ommatidium consist of a laminar cornea, which is flat externally and convex internally, and a bipartite crystalline cone. Sometimes seven and sometimes eight retinular cells closely appose the proximal tip of the cone and bear the microvilli of the rhabdom. Proximal to the rhabdom the retinular cells form thin pillars near the periphery of the ommatidium, and the central portion along the optic axis at this level is occupied by interstitial cells that contain massive arrays of clear vesicles thought to serve as reflective elements. The arhabdomeral segments of the retinular cells and the interstitial cells rest on a basement membrane. Within each ommatidium the basement membrane has two extensions with cylindrical cores and thin sheets of dense material and collagen-like filaments. These sheets occupy spaces between adjacent interstitial cells up to the level of the rhabdomeral segments of the retinular cells. Arrays of pigment cells with relatively weak light-screening properties separate adjacent ommatidia.Animals were fixed both in light within a week of being brought from depth into daylight, and after 2 months of maintenance in constant darkness following such daylight exposure. In both cases, microvilli of the rhabdom were severely disrupted and the retinular cytoplasm contained numerous multivesicular bodies. Exposure to natural daylight appears to cause irreversible structural damage to the photoreceptors of these animals.
    Additional Material: 8 Ill.
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  • 5
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Tetrachlorodiphenoquinones have the same exact mass and elemental composition as the toxic environmental contaminant 2,3,7,8-tetrachlorodibenzo-p-dioxin. However, analysis of 3,3′-5,5′-tetrachlorodiphenoquinone showed a pronounced tendency toward chemical reduction in the mass spectrometer to the quinol compound, producing a molecular ion two mass units higher than 2,3,7,8-tetrachlorodibenzo-p-dioxin. Distinct differences were also apparent between the mass spectral fragmentation patterns of 3,3′,5,5′-tetrachlorodiphenoquinone and 2,3,7,8-tetrachloridibenzo-p-dioxin. The 3,3′,5,5′-tetrachlorodiphenoquinone spectrum shows a successive loss of carbon monoxide, with the most prominent fragment corresponding to loss of two molecules of carbon monoxide plus chlorine. In the mass fragmentation of 2,3,7,8-tetrachlorodibenzo-p-dioxin carbon monoxide loss is suppressed, but loss of one molecule of carbon monoxide plus chlorine is a major fragment ion. During an alumina column clean-up procedure 3,3′,5,5′-tetrachlorodiphenoquinone did not coelute with the fraction containing 2,3,7,8-tetrachlorodibenzo-p-dioxin. This evidence indicates that tetrachlorodiphenoquinones are unlikely to interfere with mass spectrometric determination of 2,3,7,8-tetrachlorodibenzo-p-dioxin in environmental samples.
    Additional Material: 4 Ill.
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  • 6
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Syntheses of Biologically Important Carbohydrates, 35.  -  Synthesis of Exocyclic Saccharide Enol Ethers and Their Reaction to Branched-chain CarbohydratesWittig olefination of the 3-uloses 1 and 9 leads to the exocyclic (E)- and (Z)-enol ethers 2 and 3 or 11 and 10, respectively. On cis-hydroxylation these are uniformly transformed into the hydroxyformyl-branched gluco derivatives 4 and 8, respectively. Acidolysis of 2a as well as mercuri or iodo hydroxylation with subsequent reduction give the 3-C-formyl-branched sugars 12 and 13. Alternatively, the latter may also be obtained by treatment of the ulose 1 with tosylmethyl isocyanide via the cyano-branched compound 16. Addition of iodine/ silver isocyanate to 2a and subsequent methanolysis gives the epimeric 3-deoxy-3-iodo-3′-aminals 14 and 15 which on treatment with base yield the substituted aziridine 17 or the branched olefin sugar derivative 18, respectively.
    Notes: Durch Wittig-Olefinierung der 3-Ulosen 1 und 9 werden die exocyclischen (E)- und (Z)-Enolether 2 und 3 bzw. 11 und 10 gewonnen. Deren cis-Hydroxylierung führt einheitlich zu den Hydroxyformyl-verzweigten Derivaten mit gluco-Konfiguration 4 bzw. 8. Bei der Acidolyse sowie den Mercuri- oder Iodhydroxylierungen nebst Reduktion von 2a werden die 3-C-Formyl-verzweigten Zucker 12 und 13 erhalten, von denen 13 auch durch Umsetzung der Ulose 1 mit Tosylmethylisocyanid über die Cyan-verzweigte Komponente 16 erhalten werden kann. Mit Iod/Silberisocyanat werden aus 2a nach Methanolyse die epimeren 3-Desoxy-3-iod-3′-aminale 14 und 15 gewonnen. 14 reagiert mit Base zum substituierten Aziridin 17, 15 zum verzweigten Olefinzuckerderivat 18.
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  • 7
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Biologie in unserer Zeit 16 (1986), S. 169-178 
    ISSN: 0045-205X
    Keywords: Life and Medical Sciences
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Additional Material: 16 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Cell Biochemistry and Function 4 (1986), S. 123-130 
    ISSN: 0263-6484
    Keywords: Fasting ; pancreatic islets ; insulin release ; 45Ca and 86Rb fluxes ; glucose ; 2-ketoisocaproate ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: In pancreatic islets removed from 48 h-fasted rats, as distinct from fed animals, the release of insulin evoked by D-glucose is more severely impaired than that evoked by 2-ketoisocaproate. This decreased secretory response to D-glucose contrasts with an unimpaired cationic response to the sugar in terms of the glucose-induced decrease in both 86Rb and 45Ca outflow from pre-labelled islets. Likewise, fasting only causes a modest decrease of the secondary rise in 45Ca outflow evoked by D-glucose in islets perifused at normal Ca2+ concentration. The latter decrease appears more marked, however, if the cationic response to glucose is expressed relative to that evoked by 2-ketoisocaproate in islets removed from rats in the same nutritional state. It is concluded that, in the process of nutrient-stimulated insulin release, neither the decrease in K+ conductance (inhibition of 86Rb outflow) nor the sequestration of Ca2+ by intracellular organelles and/or direct inhibition of Ca2+ outward transport (decrease in 45Ca outflow) represent the sole determinant(s) of the subsequent gating of Ca2+ channels (secondary rise in 45Ca efflux).
    Additional Material: 3 Ill.
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  • 9
    ISSN: 0044-8249
    Keywords: Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
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  • 10
    ISSN: 0044-8249
    Keywords: Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
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