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  • 1
    Electronic Resource
    Electronic Resource
    Evolutionary relationships of eukaryotic kingdoms (1996)
    Springer
    Journal of molecular evolution 42 (1996), S. 183-193 
    Details
    ISSN: 1432-1432
    Keywords: Small-subunit ribosomal RNA ; Phylogeny ; Animals ; Fungi ; Plants ; Alveolates ; Heterokonts ; Stramenopiles
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The evolutionary relationships of four eukaryotic kingdoms—Animalia, Plantae, Fungi, and Protista—remain unclear. In particular, statistical support for the closeness of animals to fungi rather than to plants is lacking, and a preferred branching order of these and other eukaryotic lineages is still controversial even though molecular sequences from diverse eukaryotic taxa have been analyzed. We report a statistical analysis of 214 sequences of nuclear small-subunit ribosomal RNA (srRNA) gene undertaken to clarify these evolutionary relationships. We have considered the variability of substitution rates and the nonindependence of nucleotide substitution across sites in the srRNA gene in testing alternative hypotheses regarding the branching patterns of eukaryote phylogeny. We find that the rates of evolution among sites in the srRNA sequences vary substantially and are approximately gamma distributed with size and shape parameter equal to 0.76. Our results suggest that (1) the animals and true fungi are indeed closer to each other than to any other “crown” group in the eukaryote tree, (2) red algae are the closest relatives of animals, true fungi, and green plants, and (3) the heterokonts and alveolates probably evolved prior to the divergence of red algae and animal-fungus-green-plant lineages. Furthermore, our analyses indicate that the branching order of the eukaryotic lineages that diverged prior to the evolution of alveolates may be generally difficult to resolve with the srRNA sequence data.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02198844
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  • 2
    Electronic Resource
    Electronic Resource
    Energy dependence of photon-induced Kα and Kβ x-ray fluorescence cross-sections for some elements with 20 ≤ Z ≤ 56 (1985)
    New York, NY [u.a.] : Wiley-Blackwell
    X-Ray Spectrometry 14 (1985), S. 165-169 
    Details
    ISSN: 0049-8246
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Kα and Kβ x-ray fluorescence cross-sections were measured at ten excitation energies ranging from 5.96 to 59.54 keV for elements with 20 ≤ Z ≤ 56 and the experimental results were compared with the theoretical values. Fairly good agreement was observed within the uncertainties of the determinations. This is the first time that measurements have been made for ten elements at a number of excitation energies and Kβ XRF cross-sections are also reported for the first time.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/xrs.1300140406
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  • 3
    Electronic Resource
    Electronic Resource
    Measurement of K X-ray fluorescence cross-sections for some elements with 23 ≤ Z ≤ 55 in the energy range 8-60 kev (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    X-Ray Spectrometry 16 (1987), S. 203-206 
    Details
    ISSN: 0049-8246
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Kα and Kβ X-ray fluorescence cross-sections were measured for V, Mn, Co, Br, Rb, Mo, In, Sb, I and Cs at nine excitation energies ranging from 8 to 60 keV using energy-dispersive X-ray fluorescence spectrometry. The results were in good agreement with the theoretical values calculated using photoionization cross-sections based on the Hartree-Fock-Slater model.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/xrs.1300160504
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  • 4
    Electronic Resource
    Electronic Resource
    Contribution due to excitation by scattered photons in measurements of L x-ray cross-sections (1989)
    New York, NY [u.a.] : Wiley-Blackwell
    X-Ray Spectrometry 18 (1989), S. 193-198 
    Details
    ISSN: 0049-8246
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The relative contribution to the production of target L x-rays by the scattered and K x-ray parts of excitation spectra from different secondary excitors in annular source geometry is estimated. In contrast to the observations of N. Singh et ul., who made similar measurements using triaxial geometry, we found only a small contribution to the production of L x-rays by the scattered part of the excitation spectrum in comparison with that by the K x-ray part. We crosschecked the observations by measuring L x-ray cross-sections for five elements, Pr, Nd, Sm, Tb and Yb, at 22.6 keV by two methods: (i) using a 109Cd radioisotope source in the direct excitation mode and (ii) using a secondary excitor of Ag with a 241Am radioisotope source as the primary excitor, in annular source geometry. The results obtained by the two methods are found to be in good agreement.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/xrs.1300180503
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  • 5
    Electronic Resource
    Electronic Resource
    Matrix corrections for quantitative determination of trace elements in biological samples using energy-dispersive X-ray fluorescence spectrometry (1989)
    New York, NY [u.a.] : Wiley-Blackwell
    X-Ray Spectrometry 18 (1989), S. 207-210 
    Details
    ISSN: 0049-8246
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: An experimental method for the evaluation of the matrix absorption correction (8) for the determination of trace elements in thick biological samples using EDXRF is discussed. The validity of the method was checked in two ways, first by comparing the experimental values with theoretical estimated values for samples of known matrix and second by analysing NBS biological standards in the form of thick pellets. It was found that a sample thickness of 40-70 mg cm-2 is, in general, optimum for the analysis of biological samples in pellet form with an excitation energy of 22.6 keV.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/xrs.1300180505
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  • 6
    Electronic Resource
    Electronic Resource
    13C NMR chemical shifts and substituent effects transmission in 1,7,7-trimethyl-3-[(E)-2′-arylethenyl]-2-oxabicyclo[4.4.0]deca-3,5-dienes (1990)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 28 (1990), S. 212-218 
    Details
    ISSN: 0749-1581
    Keywords: 13C NMR chemical shifts ; 13C NMR substituent effect transmission ; 1,7,7-Trimethyl-3-[(E)-2′-arylethenyl]-2-oxabicyclo[4.4.0]deca-3,5-dienes ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 13C NMR chemical shifts were determined for all carbons in a number of 1,7,7-trimethyl-3-[(E)-2′-arylethenyl]-2-oxabicyclo[4.4.0]deca-3,5-dienes [aryl = C6H5, C6H4CH3-p, C6H4F-p, C6H4Cl-p, C6H4Br-p, C6H4CN-p, C6H4NO2-p, C6H4OCH3-p, C6H3(OCH3)2-m, p and α-furyl]. Substituent chemical shift (Δδ13C) values for C-1, C-3, C-4, C-5, C-6, C-1′, C-2′, C-3′ and C-4′,8′ were correlated with various Hammett parameters by singleparameter analysis. The correlations revealed that the substituent effects are transmitted across three π-bonds in conjugation with the aryl ring. Dual-substituent-parameter treatment of the substituent chemical shifts revealed that resonance plays a major role in the substituent effect transmission. Hammett parameters were also derived for the α-furyl substituent.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1260280304
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