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  • 1
    ISSN: 1432-2242
    Keywords: Apomixis ; Asynapsis ; B III hybrids ; Genome analysis ; Wheat ; Wide hybridization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Wheat (Triticum aestivum L., 2n = 6x = 42, AABBDD) florets were emasculated and pollinated using two apomictic wheatgrass [Elymus rectisetus (Nees in Lehm.) A. Love & Connor, 2n = 6x = 42, SSYYWW] accessions, one of which produces 2n pollen. A 2n = 42 (BII) hybrid and four 2n = 63 (B III) hybrids were obtained. The spike morphology of the B II hybrid was intermediate to that of its parents. The pollen mother cells (PMCs) of this hybrid contained on average 38.361 and 1.62 II, which was consistent with its disparate genome composition (ABDSYW). Its pollen failed to stain and no BC1 progeny was obtained. The B III hybrids (reduced egg fertilized with unreduced sperm) were grasslike and had a full complement of E. rectisetus chromosomes, the synapsis of which was slightly impaired by wheat haplome and/or cytoplasm. Their PMCs contained on average 16.30 II, 25.72 I, and 1.54 multivalents (III plus IV). Pollen stainability in these hybrids was low (〈1%), and when they were used as females, one 54- and 60-chromosome BC1 were obtained. A mean of 13.25 II was observed in PMCs of the 54-chromosome BC1 and pollen stainability was 10%. Pollen stainability in the 60-chromosome BC1 was only 5%. The use of 2n-pollen-producing E. rectisetus accession accelerated hybrid and BC1 formation and may accelerate the ultimate transfer of apomixis to wheat.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1617-4623
    Keywords: Key words Differential display ; Heterosis ; RNA-binding protein ; Wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A hybrid-specific expressed cDNA fragment, designated as AG5, has been identified in wheat seedling leaves using differential mRNA display. AG5 contains an open reading frame (ORF) encoding 183 amino acid residues. Comparison with amino acid sequences in GenBank revealed that the AG5 protein is homologous to a group of Gly-rich proteins with consensus sequence-type RNA-binding domains (CS-RBD). Structural analysis showed that AG5 protein contains five motifs, including a consensus sequence-type RNA-binding domain near its N-terminus, arginine/aspartic acid repeats and a Gly-rich region in its center, a Cys-X2-Cys-X4-His-X4-Cys (CCHC) zinc finger motif in the Gly-rich region, and TrySer2ArgAsp2Arg repeats towards its C-terminus. Of all previously described RNA-binding proteins, only RZ-1 from tobacco has a similar structure to the AG5 protein, but RZ-1 lacks a TrySer2ArgAsp2Arg repeat motif, indicating that the two proteins may belong to a family of closely related proteins in plants. The possible role of AG5 and its relation to wheat heterosis are discussed.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Macromolecular Chemistry and Physics 198 (1997), S. 983-995 
    ISSN: 1022-1352
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The self-diffusion coefficients of a styrene-isoprene diblock and a styrene-isoprene-styrene triblock copolymer have been measured as functions of concentration in the neutral good solvent toluene. The sample block molecular weights are 1.0 × 104 and 5.0 × 104 g/mol for the diblock, and 1.0 × 104, 1.0 × 105 and 1.0 × 104 g/mol for the triblock, and the samples are designated SI-60 and SIS-120, respectively. Synchrotron small-angle X-ray scattering was utilized to locate the ordering transitions, and to identify the morphologies. SI-60 exhibited an order-order transition from a hexagonal to a cubic structure (i.e., from cylinders to spheres), prior to disordering, whereas SIS-120 only exhibited the hexagonal phase. These results were compared to the melt, where both materials exhibit the cylinder-to-sphere transition. The concentration range for diffusion measurements extended into the ordered state: weight fractions up to 0.78 for SI-60 and 0.62 for SIS-120, where the corresponding ordering concentrations are 0.67 and 0.56. Diffusion measurements were performed by forced Rayleigh scattering and by pulsed-field-gradient NMR. The results indicate that substantial concentration fluctuations arise in solution prior to the ordering transition, and that these fluctuations act to retard chain diffusion. However, from comparison of the diblock and triblock mobilities, it appears that the retardation of mobility in the fluctuating and ordered states is due more to the increased monomeric friction in the (cylindrical) styrene-rich microdomains, than to the thermodynamic barrier for escape of the styrene blocks from these microdomains.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 59 (1996), S. 1087-1098 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Talc surface treatment was carried out using a series of phosphate coating levels. The coated talc was characterized using quantitative diffuse reflectance FTIR analysis, which revealed a saturation of surface coverage at around 6 wt % phosphate. Coated and uncoated talc had a nucleation effect; and the degree of crystallinity of composites increased initially, then gradually decreased with increasing phosphate coating level. The talc dispersion was improved as coating level increased; however, the platelet alignment was reduced. The addition of 0.5 wt % phosphate to talc resulted in a maximum increase in tensile strength and a significant drop in flexural modulus. Improvement of falling weight impact properties of the composites were achieved at high coating levels. © 1996 John Wiley & Sons, Inc.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 33 (1995), S. 2289-2293 
    ISSN: 0887-6266
    Keywords: block copolymer ; order-disorder transition ; neutral solvent ; dilution approximation ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 51 (1994), S. 1159-1164 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The effect of interaction between carbon black and polymer on electrical behavior was studied using the ESR method. The polymer matrices used were HDPE, LDPE, and ethylene/vinyl acetate (EVA). Two kinds of carbon blacks (CB), high structure CSF-III and low structure FEF, were used as a conductive filler. Compared to that of the HDPE/FEF compound, the positive temperature coefficient (PTC) intensity is lower and electrical reproducibility is worse for the HDPE/CSF-III compound; however, it can be improved significantly by radiation cross-linking. On the other hand, the cross-linking has no practical effect on the PTC intensity of the LDPE/CSF-III compound while it can be achieved by mixing the compound for a longer time. The great PTC intensity was obtained in the HDPE/EVA/CSF-III compound, and it is greater than that of HDPE/CSF-III or EVA/CSF-III. We explain these results using the concept of interaction between the filler and matrix. The absorption of the polymer on the carbon black surface may be physical or chemical; the latter is caused by the free-radical reaction between the polymer and carbon black, and it can occur during the radiation or preparation process of the compound. These “bound polymers” are essentially important for materials to have a great PTC intensity and good reproducibility. © 1994 John Wiley & Sons, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Propellants, Explosives, Pyrotechnics 11 (1986), S. 10-15 
    ISSN: 0721-3115
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The thermal analysis technique was used to rapidly evaluate the compatibility of explosives with contacted materials. The three kinetic parameters viz. activation energy E, reaction order n and pre-exponential factor A were calculated from three characteristic temperatures of a single DTA curve. The compatibility was evaluated from the four parameters E, n and the characteristic temperatures Tm (peak maximum) and To (decomposition starting point on the DTA curve). The results are compared to those obtained from the gasometric method.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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