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  • Organic Chemistry  (7)
  • Arene complexes  (2)
  • Electron microscopy  (2)
  • 1
    Digitale Medien
    Digitale Medien
    Amsterdam : Elsevier
    Biochimica et Biophysica Acta (BBA)/Gene Structure and Expression 696 (1982), S. 76-86 
    ISSN: 0167-4781
    Schlagwort(e): (Adenovirus) ; Chromatin ; Electron microscopy ; Nuclease digestion
    Quelle: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Thema: Biologie , Chemie und Pharmazie , Medizin , Physik
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    ISSN: 1432-072X
    Schlagwort(e): Bradyrhizobium ; Electron microscopy ; Mutants ; Nitrogen fixation ; Nodulation ; Soybean ; Symbiosis ; Transposon Tn5
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The genome of the slow-growing Bradyrhizobium japonicum (strain 110) was mutagenized with transposon Tn5. A total of 1623 kanamycin/streptomycin resistant derivatives were screened in soybean infection tests for nodulation (Nod) and symbiotic nitrogen fixation (Fix). In this report we describe 14 strains possessing a stable, reproducible Nod+Fix- phenotype. These strains were also grown under microaerobic culture conditions to test them for free-living nitrogen fixation activity (Nif). In addition to strains having reduced Fix and Nif activities, there were also strains that had reduced symbiotic Fix activity but were Nif+ ex planta. Analysis of the genomic structure revealed that the majority of the strains had a single Tn5 insertion without any further apparent physical alteration. A few strains had additional insertions (by Tn5 or IS50), or a deletion, or had cointegrated part of the vector used for Tn5 mutagenesis. One of the insertions was found in a known nif gene (nifD) whereas all other mutations seem to affect different, hitherto unknown genes or operons. Several mutant strains had an altered nodulation phenotype, inducing numerous, small, widely distributed nodules. Light and electron microscopy revealed that most of these mutants were defective in different stages of bacteroid development and/or bacteroid persistence. The protein patterns of the mutants were inspected by two-dimensional gel electrophoresis after labelling microaerobic cultures with l-(35S)methionine. Of particular interest were mutants lacking a group of proteins the synthesis of which was known to be under oxygen control. Such strains can be regarded as potential regulatory mutants.
    Materialart: Digitale Medien
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  • 3
    Digitale Medien
    Digitale Medien
    Springer
    Theoretical chemistry accounts 91 (1995), S. 157-167 
    ISSN: 1432-2234
    Schlagwort(e): Density functional theory ; Metal-ligand bond energies ; Chromium ; Arene complexes ; Chalcocarbonyls
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary Quantum chemical calculations based on density functional theory have been performed on Cr(CO)6, (η6-C6H6)Cr(CO)3 and (η6-C6H6)Cr(CO)2(CS) at the local and nonlocal level of theory using different functionals. Good agreement is obtained with experiment for both optimized geometries and metal-ligand binding energies. In particular, a comparison of metal-arene bond energies calculated for the (η6-C6H6)Cr(CO)3 and (η6-C6H6)Cr(CO)2(CS) complexes correlates well with kinetic data demonstrating that substitution of one CO group by CS leads to an important labilizing effect of this bond, which may be primarily attributed to a larger π-backbonding charge transfer to the CS ligand as compared with CO.
    Materialart: Digitale Medien
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  • 4
    Digitale Medien
    Digitale Medien
    Springer
    Theoretica chimica acta 91 (1995), S. 157-167 
    ISSN: 0040-5744
    Schlagwort(e): Key words: Density functional theory ; Metal-ligand bond energies ; Chromium ; Arene complexes ; Chalcocarbonyls
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary.  Quantum chemical calculations based on density functional theory have been performed on Cr(CO)6, (η6-C6H6)Cr(CO)3 and (η6-C6H6)Cr(CO)2(CS) at the local and nonlocal level of theory using different functionals. Good agreement is obtained with experiment for both optimized geometries and metal–ligand binding energies. In particular, a comparison of metal–arene bond energies calculated for the (η6-C6H6)Cr(CO)3 and (η6-C6H6)Cr(CO)2(CS) complexes correlates well with kinetic data demonstrating that substitution of one CO group by CS leads to an important labilizing effect of this bond, which may be primarily attributed to a larger π-backbonding charge transfer to the CS ligand as compared with CO.
    Materialart: Digitale Medien
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  • 5
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 316 (1974), S. 13-18 
    ISSN: 0021-8383
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Die Addition von Oxalessigester an 2,4; 3,5-Di-O-benzyliden-al-D-xylose 1 führt zum 3-Äthoxycarbonyl-3-desoxy-5,7; 6,8-di-O-benzyliden-D-gulo-oktulosonsäure-äthylester 2, aus dem man durch Erwärmen mit verd. Salzsäure in Dioxan die 2-Desoxy-D-gulo-heptose 3 erhält. Beim Schütteln mit konz. Salzsäure und Benzylmercaptan entsteht aus 3 unter Abspaltung von Wasser das [2-Hydroxymethyl-furanyl(5)]-acetaldehyd-dibenzylmercaptal 6. Der Ketosäureester 2 kann in einer Keto-(2 a) und in einer Enol-Form 2 b auftreten. Von letzterer leiten sich das 2,4-Di-O-acetat 4 und der 2,4-Di-O-methyläther 5 ab. Die D-gulo-Konfiguration der Verbindungen 2, 3, 4 und 5 wird durch Überführen des Methyläthers 5 in den O-Methyl-L-äpfelsäure-bis-(p-bromphenacylester) 10 bewiesen.
    Materialart: Digitale Medien
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  • 6
    ISSN: 0021-8383
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Retentionsindices und ΔI-Werte von 59 Kohlenwasserstoffen verschiedener Ringsysteme, die in entsprechenden Fraktionen flüssiger Crackprodukte der Äthylenerzeugung vorkommen bzw. bei der thermischen Homo- und Codimierisierung der darin enthaltenen cyclischen und acyclischen Diene entstehen, wurden bei 60° an Kapillarsäulen mit Squalan und Polypropylenglykol 425 vermessen. Die Ergebnisse werden mitgeteilt und Zusammenhänge zwischen Kohlenwasserstoffstruktur und ΔI-Werten diskutiert.Für die untersuchten endo- und exo-Norbornene wird an Hand der ΔI-Werte gezeigt, daß eine Epimerenzuordnung mit Hilfe der Kapillar-Gaschromatographie möglich ist.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
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  • 7
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 50 (1967), S. 68-84 
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The electronic spectrum and the polarisation of the transitions have been determined in the region from 15000 to 50000 cm-1 for the 2-acetamino derivative of trans-15, 16-dimethyl-dihydropyrene, whose spectrum resembles closely that of the parent compound and its di-ethyl analogue. It is shown that the sequence of states is 1Lb, 1La, 1Bb, 1Ba, in agreement with theoretical predictions which were deduced from a configuration interaction model for the D2h-π-perimeter of these systems. The influence of inductive and hyperconjugative effects on the band positions and the band intensities has been discussed.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 8
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 55 (1972), S. 921-937 
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Irradiation of Δ5,7-9α, 10β-steroids in solution with λ = 253,7 nm yielded no Δ5,7-9β, 10α-steroids and vice versa. No back reaction from precalciferol2 to ergosterol could be detected by kinetic measurements. This leads to the conclusion that with the mercury resonance line only ring opening and 6,7-cis/trans isomerization but no ring closure occurs.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
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  • 9
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 51 (1968), S. 225-240 
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The electronic spectra and the polarisation of the transitions have been determined for the 1,6-methano-[11] annulenium cation III and the 4,6-dimethyl-1,2-benzotropylium cation IV. The observed sequence of polarisation of the prominent bands corresponding to the lowest electronically excited states is in agreement with the predictions derived from molecular orbital models of the PARISER-PARR-POPLE type. The influence of partial conjugation between the bridged centre and of the inductive effect of the methylene group in III has been investigated.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
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  • 10
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 3 (1989), S. i 
    ISSN: 0268-2605
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
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