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  • 1
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Solid state phenomena Vol. 47-48 (July 1995), p. 473-484 
    ISSN: 1662-9779
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Physics
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Plant breeding 116 (1997), S. 0 
    ISSN: 1439-0523
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Seed regeneration is one of the most important tasks in genebank work. To regenerate germplasm of allogamous, entomophilous plant species in isolation facilities, insects are often used as pollen vectors. The objective of this study was to determine the effect of pollinator species, pollinator densities, pollinator combinations, and flower preferences on the seed quantity and quality of Daucus carota, Allium cepa, and Brassica rapa. The isozyme phosphoglucoisomerase (PGI) served as genetic marker in determining outcrossing rates and pollen dispersal distances. Field plots and isolation cages without insects were used as controls. The pollinators studied consisted of the following insect species from German native fauna: red mason bees (Osmia rufa L.), hoverflies (Eristalis tenax L.), and blowflies (Calliphora sp. and Lucilia sp.). In D. carota and B. rapa, higher seed yields were achieved in isolation cages than in field plots, but in A. cepa lower seed yields were obtained in the isolation cages. Although O. rufa showed no liking for A. cepa, unintentional pollination was effected by this insect in isolation cages. Lower insect densities were necessary for O. rufa than for the various fly species.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Plant breeding 114 (1995), S. 0 
    ISSN: 1439-0523
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: The sexual propagation of genebank accessions by hand pollination in the greenhouse is a very expensive and time-consuming routine task. The self-incompatibility of most diploid potato species allows their multiplication in isolated field plots, which is coupled with the advantage of the presence of natural pollinators and maintaining a high level of heterozygosity. The aim of this study was to determine the isolation distance required for minimizing pollen flow between neighbouring multiplication plots. The Solanum phureja clone IVP48 was used as the pollen donor since it possesses a dominant seed marker (‘embryo spot’). The centrally located pollen donor was surrounded by S. phureja recipient plots at distances of 10,20,40, and 80 m, respectively. The average pollen contamination ranged from 0.2% in the plots 80 m from the pollen donor to 5.1% in those 10 m away. In this study, procedures are suggested which will help to reduce cross-pollination between accessions.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 67 (1995), S. 1292-1294 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Narrow Ge layers embedded in Si are investigated using photoluminescence (PL) spectroscopy. With increasing layer thickness a growth mode changeover from two-dimensional (2D) strained-layer growth to three dimensional Stranski–Krastanov growth is observed. Additional PL lines that are redshifted with respect to the PL signal of the 2D strained layers are attributed to islands formed by three-dimensional growth. The occurrence of these new lines is accompanied by a blueshift of the PL of the 2D layers, indicating a strong Ge diffusion from the 2D layers towards the islands. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Crop science 39 (1999), S. 1815-1823 
    ISSN: 1435-0653
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Cichorium intybus L.; RC) and Jerusalem artichoke (Helianthus tuberosus L.; JA) into agricultural production systems is desirable to diversify crop rotation. Field experiments were conducted to compare the agronomic performance of RC and JA with sugar beet (Beta vulgaris L.; SB). One set of cultivars during 1995, 1996, and 1997 and an additional set in 1997 were grown on a sandy loam soil (Haplic Luvisol) at Braunschweig, Germany. Crops were cultivated with and without supplemental irrigation, complete and no weed control (1995 and 1996), and N fertilization rates of 0, 60, and 120 kg ha−1. Severe water stress caused significant but similar storage organ yield losses in all crops, whereas mild water stress mainly affected JA yields. Averaged across years and N levels, storage organ yield losses through weed competition under irrigation amounted to 70, 47, and 8% in SB, RC, and JA, respectively. Averaged across years, in the absence of water and weed stress, SB, RC, and JA at their respective optimal N levels gave root and tuber dry matter yields of 14.8, 15.0, and 11.5 Mg ha−1, and sugar yields of 11.5, 11.2, and 8.1 Mg ha−1, respectively. Maximal SB and JA yields generally were achieved at the highest N rate, while RC peak yields were attained at 60 kg N ha−1. With the same amount of N taken up, RC in 1995 and SB in 1996 and 1997 produced the highest sugar yields.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1432-0630
    Keywords: PACS: 52.40.Nk; 52.50.Jm; 52.70.Kz
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract. Shadowgraphic and interferometric images of vapor/plasma plumes generated by pulses of a ns-Nd:YAG laser reveal the distinctive behavior of the shock wave expansion for each of three processing wavelengths (1064 nm, 532 nm, and 355 nm), indicating that different mechanisms dominate the interaction between the optical fields and the material vapor/plasma. Electron density distributions within the plasma plumes calculated from interferometrically obtained refractive index distributions allow us to describe the regions of absorption and the absorption mechanisms using a simple model of inverse bremsstrahlung and photoionization, which allows us to estimate absorption coefficients.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Euphytica 95 (1997), S. 57-66 
    ISSN: 1573-5060
    Keywords: Lycopersicon esculentum ; tomato landraces ; salt stress tolerance ; osmotic adjustment ; adaptation ; breeding potential
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Tomato is an important vegetable crop in Kenya and the development of salt tolerant cultivars would enhance its productivity in the vast marginal areas of the country. This study was aimed at determining the magnitude of genotypic variability for salt tolerance in the Kenyan tomato germplasm. Pot experiments with 22 landraces and 9 market cultivars were laid out as a two and four replicate split-plot design in glasshouse in Experiments 1 and 2, respectively. Salt treatments in Experiment 1 were 0 and 5 g NaCl kg-1 resulting into 0.5 and 9.1 dS m-1 of the soil saturation extracts, respectively. In Experiment 2 the treatments were 0, 4, and 8 g NaCl kg-1 soil corresponding to 0.5, 7.4, and 14.2 dS m-1, respectively. Data were recorded on agronomic and biochemical parameters. The germplasm showed large variation for salt tolerance. Fruit and seed production at soil salinity of 14.2 dS m-1 demonstrated that these tomatoes are fairly tolerant of NaCl. Osmotic adjustment was achieved by higher fruit electrical conductivity, brix and total titratable acidity. Low and high contents of K+, Ca2+ and Mg2+ within tomato tissues and soil, respectively, under salt treatment, confirmed competition and antagonism involving Na+ and these cations. Low Na+ and Cl- contents in the fruit at 7.4 dS m-1 revealed their exclusion and ensured production of physiologically normal seeds and nutritionally healthy fruits. Two landraces ‘Chwerotonglo’ and ‘Nyanyandogo’ were identified as salt tolerant. Comparatively, the market cultivars showed superior fruit yields despite their susceptibility to salinity. Accordingly, tolerance of landraces in combination with superior yields of the market cultivars is suitable for tomato improvement for salt tolerance.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Macromolecular Chemistry and Physics 199 (1998), S. 273-282 
    ISSN: 1022-1352
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: 2,2-Dibutyl-2-stanna-1,3-dioxacycloalkanes were prepared from dibutyltin oxide and 1,2-ethanediol, 1,3-propanediol or 1,4-butanediol. These tin heterocycles reacted stoichiometrically with double molar amounts of γ-thiobutyrolactone by a stepwise insertion. In contrast to γ-thiobutyrolactone an excess of γ-thiocaprolactone resulted in additional insertion steps, i.e., polymerization of the thiolactone. Analogous insertion reactions were performed with a spirocyclic stannoxane derived from pentaerythritol. With ε-caprolactone macrocyclic polymerization took place without stoichiometric intermediates. When the 2,2-dibutylstanna-dioxepane was reacted with an equimolar amount of 1,3-dithian-2-one, the insertion step was immediately followed by a ring contraction reaction yielding 2-stanna-1,3-dithiane and trimethylene carbonate which polymerized immediately. The application of this reaction sequence to macrocyclic stanna poly(ε-caprolactone) yielded tin-free macrocycles along with 2,2-dibutyl-2-stanna-1,3-dithiane. This reaction sequence allows the synthesis of nontoxic, biodegradable macrocyclic polyesters.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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