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  • 1
    Electronic Resource
    Electronic Resource
    Low-temperature resistance in Polylepis tarapacana, a tree growing at the highest altitudes in the world (2001)
    Oxford, UK : Blackwell Science Ltd
    Plant, cell & environment 24 (2001), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The Polylepis tarapacana forests found in Bolivia are unique with respect to their altitudinal distribution (4200–5200 m). Given the extreme environmental conditions that characterize these altitudes, this species has to rely on distinct mechanisms to survive stressful temperatures. The purpose of this study was to determine low-temperature resistance mechanisms in P. tarapacana. Tissue was sampled for carbohydrate and proline contents and micro-climatic measurements were made at two altitudes, 4300 and 4850 m, during both the dry cold and wet warm seasons. Supercooling capacity (−3 to −6 °C for the cold dry and −7 to −9 °C for the wet warm season) and injury temperatures (−18 to −23 °C for both seasons), determined in the laboratory, indicate that P. tarapacana is a frost-tolerant species. On the other hand, an increase in supercooling capacity, as the result of significant increase in total soluble sugar and proline contents, occurs during the wet warm season as a consequence of higher metabolic activity. Hence, P. tarapacana, a frost-tolerant species during the colder unfavourable season, is able to avoid freezing during the more favourable season when minimum night-time temperatures are not as extreme.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-3040.2001.00685.x
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  • 2
    Electronic Resource
    Electronic Resource
    Die gerbstoffe der Acacia arabica II. Mitt. Isolierung verschiedener polyhydroxyphenole aus den fruchtschoten
    Amsterdam : Elsevier
    Phytochemistry 2 (1963), S. 151-156 
    Details
    ISSN: 0031-9422
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/S0031-9422(00)82975-1
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Electrodiffusion characterization of non-Newtonian flow through packed beds (1991)
    Springer
    Journal of applied electrochemistry 21 (1991), S. 1087-1090 
    Details
    ISSN: 1572-8838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract The limiting current technique, involving the cathodic controlled reduction of ferricyanide ions, has been used in order to characterize the axial dispersion and the solid-liquid mass transfer for a non-Newtonian shear thinning power-law fluid flowing through fixed beds of spherical and parallelepipedal particles. For each of the two phenomena, results corresponding to Newtonian and non-Newtonian power-law flow at low Reynolds numbers can be described by the same dimensionless equation for beds packed with particles of the same shape.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01041452
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    A chemical and biological approach towards the definition of calcareous soils (1973)
    Springer
    Plant and soil 39 (1973), S. 479-486 
    Details
    ISSN: 1573-5036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary A pot culture experiment was conducted to determine the CaCO3 percentage at which it exerts its drastic effect on plant growth, P32 and Fe uptake as a criterion for the definition of calcareous soils. Soil mixtures were prepared by mixing different calculated amounts of Nile loam, fine sand and fine oolitic sand to give mixtures containing 1, 2, 4, 6, 8, 10, 20, 30, 40, and 50% CaCO3. The mixtures were so prepared that their clay contents were equal and having the same texture. Corn plants were selected for this study. The results of plant growth, P32, and Fe uptake supports each other and clearly indicate that when CaCO3 reaches 8 percent of the soil components, it controls its biological and chemical characteristics. A conclusion was drawn that 8% CaCO3 could be the margin at which the soil can be considered calcareous.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00264166
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  • 5
    Electronic Resource
    Electronic Resource
    A chemical and biological approach towards the definition of calcareous soils (1973)
    Springer
    Plant and soil 39 (1973), S. 469-478 
    Details
    ISSN: 1573-5036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Several agricultural problems are associated with the presence of certain levels of CaCO3 in soils. The level of CaCO3 at which the phosphate fixation becomes an apparent agricultural problem, is thought to be an appropriate margine at which the soil can be considered calcareous. Thus, a set of soil mixtures, ranging in CaCO3 content from 1 to 96% was prepared and used in a column study to determine the level at which the CaCO3 fraction becomes a dominant factor controlling. P32 movement and distribution. Increasing the percentage of oolitic sand, in the soil mixture, from 1 to 10% caused a sharp drop in P32 movement with soil solution and any increase in CaCO3 content above 10% did not show any further drop in P32 movement. The amount of P32 removed with the soil solution was generally low compared to that retained in soil columns. Studying the distribution of P32 in soil columns, after five displacements, has indicated that the migration of P32 from the top soil increased by increasing CaCO3 from 1 and 2 to 6%. The amount of P32 removed was however retained in lower sections. A very sharp decrease in P32 migration from the top soil was observed when CaCO3 content was raised from 8 to 10%. A similar picture was shown when the CaCO3 material used was in clay size fraction. However the sharp increase in phosphate retention in top soil sections took place at CaCO3 content of 8% rather than at 10%. A limit of 8 to 10% CaCO3 was proposed as an appropriate margine for defining calcareous soils.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00264165
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    Paper (German National Licenses)
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