Bibliothek

feed icon rss

Ihre E-Mail wurde erfolgreich gesendet. Bitte prüfen Sie Ihren Maileingang.

Leider ist ein Fehler beim E-Mail-Versand aufgetreten. Bitte versuchen Sie es erneut.

Vorgang fortführen?

Exportieren
Filter
  • Analytical Chemistry and Spectroscopy  (11)
  • classification  (2)
  • 1
    ISSN: 1573-5060
    Schlagwort(e): Brassica oleracea ; classification ; landrace groups ; morphology ; Portuguese coles
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary A morphological study was carried out to determine the relationships among Portuguese cole landraces using 58 accessions belonging to: (i) Portuguese Tronchuda cabbage (Brassica oleracea var. tronchuda Bailey syn. var. costata De Candolle, Couve Tronchuda); (ii) Portuguese Galega kale (B. oleracea var. acephala De Candolle, Couve Galega); and (iii) other economically less important coles such as Algarve cabbages (B. oleracea var. capitata L., Couve do Algarve or B. oleracea var. sabauda L., Couve Repolho-lombarda do Algarve). The cole accessions were collected from the growers, studied under field conditions during two consecutive years, and characterized using 46 morphological characters from seedling stage to ripe silique. Morphological data were analysed by numerical taxonomy techniques using UPGMA (Unweighted Pair Group Method Using Arithmetic Averages) and by principal component analysis (PCA). Phenograms based on correlation and distance coefficients showed the existence of 8 main groups (A-H). Five of these groups correspond to Tronchuda cabbage landraces: (A) “Couves de Trás-os-Montes”; (B) “Couves do Minho”; (C) “Couves from Central Portugal”; (D) “Couve Portuguesa”; (E) “Couves from Southern inland Portugal”. The three other groups correspond to: (F) cabbages; (G) miscellaneous coles; and (H) Galega kales. Landrace groups are primarily associated with morphological differences among accessions and secondly with accession geographical origin. The interannual character variation did not affect the clustering patterns of the accessions and therefore the stability of landrace classification. PCA was congruent with the landrace groups defined by the phenograms and gave supplementary information on the usefulness of the characters for the definition of the various groups.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 2
    ISSN: 1573-5060
    Schlagwort(e): allozyme variation ; allozyme polymorphism ; Brassica oleracea ; classification ; Portuguese coles
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary Isozyme analysis was used to study the genetic variation and the genetic relationships of a collection of 48 Brassica spp. including 31 Portuguese coles (Brassica oleracea L.) accessions representative of the different landraces cultivated in Portugal. Other brassicas included in this experiment were Jersey kale, kailaan, common cabbages, broccolis, cauliflower, nine-chromosome wild brassica and turnip. Nine enzymes used in the starch gel electrophoresis included: PGM, PGI, AAT, LAP, TPI, FBP, SOD, IDH and GR. Twenty-one putative loci were revealed, with 3 showing invariance and the other 18 contained 50 alleles. The allelic frequencies at these loci represented by 40 plants per accession were used to calculate the following estimators of genetic variation: % of polymorphic loci, average number of alleles per polymorphic loci, average number of alleles per locus, and index of heterozygosity. The genetic relationships were evaluated considering Nei (1978) and Rogers (1972) genetic distances between each pair of accessions whose matrices were hierarchically clustered by the UPGMA method. The accessions were also studied using the principal coordinate analysis. Portuguese Tronchuda cabbages and Galega kales have shown high genetic diversity in comparison with the other accessions. This indicates their potential variation for use in breeding programs. The UPGMA results show that the 48 accessions, with the exception of B. insularis, B. cretica, and turnip, can be clustered into 6 groups: (a) Portuguese Tronchuda cabbages, Galega kales and Algarve cabbages; (b) common cabbages and kales; (c) Couve Poda do Algarve and broccoli; (d) Algarve cabbage and common cabbages; (e) kailaan; (f) broccoli and cauliflower. The groupings obtained by the isozyme analysis are difficult to interpret considering the origin of the Brassica spp. and the morphological resemblance among the accessions.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 3
    Digitale Medien
    Digitale Medien
    Chichester [u.a.] : Wiley-Blackwell
    Journal of Raman Spectroscopy 22 (1991), S. 519-523 
    ISSN: 0377-0486
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: The Raman and infrared spectra of methyl trans-cinnamate were measured as a function of temperature in the liquid and solid phases. The temperature dependence of the band intensities established the presence of two conformers in the liquid phase (the s-cis and s-trans forms, with C=C—C=O dihedral angles equal to 0° and 180°, respectively; ΔH(s-trans)-(s-cis) = 3.43 ± 0.84 kJ mol-1) and led to the conclusion that the thermodynamically most stable s-cis form is the only form present in the solid.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 4
    Digitale Medien
    Digitale Medien
    Chichester [u.a.] : Wiley-Blackwell
    Journal of Raman Spectroscopy 18 (1987), S. 115-118 
    ISSN: 0377-0486
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Raman spectra of di-n-butylamine show bands whose temperature-dependent intensities clearly suggest the occurrence of different conformers in simultaneous equilibria. In particular, the Raman spectrum of the solid phase is compared with that of n-nonane in order to identify the more stable conformation. In addition, intensity rations vs temperature for pairs of Raman bands in the CH stretching region exhibit a smooth variation between the liquid and solid.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 5
    Digitale Medien
    Digitale Medien
    Chichester [u.a.] : Wiley-Blackwell
    Journal of Raman Spectroscopy 25 (1994), S. 353-357 
    ISSN: 0377-0486
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Ab initio SCF MO calculations at the 3-21G level and the vibrational spectra [Raman and Fourier transform (FT) IR] of liquid-phase 2-chloro- and 3-chlorostyrene are reported. For 2-chlorostyrene, the ab initio calculations predict skew and gauche minima, with an energy difference of 11.5 kJ mol-1, and no evidence of more than one conformer was found in the liquid-phase Raman and FTIR spectra. The Raman spectra of liquid 3-chlorostyrene show pairs of bands whose temperature-dependent intensities clearly suggest the occurrence of a conformational equilibrium. From these bands, assigned to non-planar cis and trans conformers, a trans-cis energy difference of 2.3 ± 0.5 kJ mol-1 was obtained for the liquid phase.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 6
    Digitale Medien
    Digitale Medien
    Chichester [u.a.] : Wiley-Blackwell
    Journal of Raman Spectroscopy 25 (1994), S. 599-605 
    ISSN: 0377-0486
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Raman spectra of styrene (S), 3-fluorostyrene (3FS), 3-chlorostyrene (3CS) and 3-methylstyrene (3MS) and their complexes in α-, β- and γ-cyclodextrins (α-, β-, γCD) were recorded at various temperatures. The substituted styrene molecules were found to provide good group frequencies, namely, vC=C and vC—H, for probing the guest molecules. Generally, the C=C oscillator is shown to be a good probe for studying conformational equilibria of the guest molecule perturbed by complex formation with the various CD molecules. The CH oscillators provide information concerning plausible structures for the complexes. On the whole, all the spectral observations are consistent with different types of structures for the (S, 3MS)-αCD and (3FS, 3CS)-αCD complexes. In particular, the Raman spectroscopic results suggest that, for 3MS-αCD the vinyl group keeps some rotational freedom. For 3FS-αCD and 3CS-αCD, it is suggested that the most electronegative fluorine and chlorine atoms are left outside the the CD cavity, with the vinyl group rotationally hindered. For the γCD complexes, the wider CD cavity sould be able to accommodate all the guest molecules considered keeping the conformer distributions of the pure liquids approximately. However, the inclusion process seems to hinder the internal rotation in such a way that even below 200 K the conformer distribution remains similar to that of the pure liquid at room temperature.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 7
    Digitale Medien
    Digitale Medien
    Chichester [u.a.] : Wiley-Blackwell
    Journal of Raman Spectroscopy 18 (1987), S. 497-500 
    ISSN: 0377-0486
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: A comparative Raman band shape study of the reorientation of monosubstituted benzene molecules (C6H5X, X = CH3, CH2Cl, CHCl2, CCl3 and C≡CCH3) in the liquid phase has been performed. Reorientational correlation functions appear to be less sensitive to molecular reorientation about the major axis (Z axis) than to rotation of the axis itself, approaching a symmetric top case. Molecular motion anisotropy is found to increase in the order C6H5CH3 〈 C6H5CH2Cl 〈 C6H5CHCl2 〈 C6H5CCl3 〈 C6H5CCCH3 as the rotation about the Z axis becomes increasingly preferred. These results are in agreement with NMR spin-lattice relaxation data.As expected for liquids with imporatant intermolecular interactions, both the free rotor and Kubo's model fail to fit the experimental correlation functions.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 8
    ISSN: 0377-0486
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Raman spectra of ethylmethylamine and ethylmethylamine-N-d, both in the liquid phase, at different temperatures, and in the solid phase were recorded. Additionally, Fourier transform IR (4000 - 400 cm-1) spectra of these compounds in the liquid phase were also obtained. Normal coordinate calculations were performed for each conformer (T, G and G′), using an optimized local symmetry force field for secondary amines. These calculations allowed the assignment of the vibrational spectra, in good agreement with the experimental evidence. Whereas in the liquid phase all the three possible conformers were detected, in the solid phase only the bands ascribed to the T conformer were observed. From the temperature dependence study of the Raman spectrum of the liquid, the enthalpy differences between conformers were determined, yielding the values 4.6 ± 0.3 kJ mol-1 for ΔHG′-T′ 3.6 ± 0.3 kJ mol-1 for ΔHG - T and 1.1 ± 0.3 kJ mol-1 for ΔHG′- G. These were compared with ab initio SCF-MO results, for the isolated molecule, in order to assess the relative importance of intra-and intermolecular effects on conformational equilibria.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 9
    Digitale Medien
    Digitale Medien
    Chichester [u.a.] : Wiley-Blackwell
    Journal of Raman Spectroscopy 24 (1993), S. 699-703 
    ISSN: 0377-0486
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: The Raman spectra of aqueous vanadium (V) solutions at different pH values, ranging from 13.1 to 7.0, are presented. The dominant bands in the range 700-1100 cm-1 are assigned to the VO symmetrical stretching of the different oligomers, using additional information from 51V NMR spectra and empirical models. The effects of pH, concentration and ionic strength on the oligomerization equilibria are discussed. The ionic strength is found to affect significantly the oligomer composition of vanadate solutions, which is of interest in biochemical and biological studies.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 10
    Digitale Medien
    Digitale Medien
    Chichester [u.a.] : Wiley-Blackwell
    Journal of Raman Spectroscopy 15 (1984), S. 224-231 
    ISSN: 0377-0486
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Evidence is provided concerning the internal rotation of the CHCl2 group in the C6H5CHCl2 molecule in the condensed phase using mainly the Raman spectra of the alkylic carbon-hydrogen stretching vibration of C6H5CHCl2 and its deuteriated analogues. Comparison of the Raman bands observed in the region of the CH stretching vibrations for the hydrogenated compound with its deuteriated derivatives allows the assingnment of two Raman bands to the C—H vibrator of the CHCl2 group. The dependence of the profiles of these bands on temperature and dilution in a series of solvents suggests a conformational equilibrium. Comparision of two different theoretical treatments of the isolated molecule enables us to reconize the importance of non-boarded interactions operating during the internal rotation of the dichloromethyl group. The experimental results, used together woth the theoretical studies, lead to the evidence for two probable rotational isomers, designated CH⊥ and CH‖ which are responsible for the two observed Raman bands.
    Zusätzliches Material: 14 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
Schließen ⊗
Diese Webseite nutzt Cookies und das Analyse-Tool Matomo. Weitere Informationen finden Sie hier...