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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Cellular and molecular life sciences 26 (1970), S. 834-836 
    ISSN: 1420-9071
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Résumé Il arrive souvent que l'on doive substituer l'ion de sodium dans les solutions physiologiques. Un effet particulier en est la compétition du substitut vis-à-vis les ions de sodium liés au sulfate de chondroitine. Nous démontrons que le sucrose ne déplace pas cette portion du sodium lié, alors que les ions de lithium et de choline possèdent une grande affinité pour ces sites de liaison, affinité moindre cependant que celle de l'ion de calcium. Les conséquences physiologiques qui en ressortent sont discutées.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Journal of applied electrochemistry 28 (1998), S. 593-600 
    ISSN: 1572-8838
    Keywords: electrooxidation ; 1024 mild steel ; localized attack ; phosphate solution ; bicarbonate solution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract The electrochemical behaviour of 1024 mild steel electrodes was investigated in the presence of 0.05–0.5m disodium phosphate aqueous solution, in the pH range 8.4 to 9.7 and from 5 to 50°C. Bicarbonate solutions were also considered for comparison. Voltammograms were obtained with a rotating gold ring steel disc electrode, and the effects of the phosphate concentration, pH, electrode rotation speed, anodic potential limit and temperature were considered. For potential sweeps in the anodic direction in phosphate solutions, the voltammograms display an oxidation peak current at low potentials and a passivity region at higher potentials. The rate-determining step of the oxidation peak current was also investigated. The oxidation current in the passivity region is virtually independent of the applied potential, temperature, pH and phosphate concentration.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Journal of applied electrochemistry 27 (1997), S. 317-324 
    ISSN: 1572-8838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract The electrochemical behaviour of 1024 mild steel electrodes is investigated in the presence of 0.05–0.5 M sodium bicarbonate in aqueous solution at pH 8.9 and 25°C. Voltammograms are obtained with a rotating gold ring-mild steel electrode and the effect of the NaHCO3 concentration, the potential limits and the rotation speed of the disc electrode is considered. The voltammograms display an oxidation peak current at low potentials, a passivity region and a transpassive region at high potentials for the potential sweep in the anodic direction. The oxidation current in the passivity region is practically independent of the applied potential and the NaHCO3 concentration. The rate-determining step of the oxidation reaction in both the oxidation peak current region and the transpassive region is determined.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Journal of applied electrochemistry 28 (1997), S. 151-160 
    ISSN: 1572-8838
    Keywords: corrosion ; 1024 mild steel ; pitting ; film breakdown ; electro-oxidation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract The passive film breakdown of 1024 mild steel induced by the presence of 0.05m chloride ions had been investigated in 0.075–0.75m bicarbonate solutions at pH8.9–9.7. A rotating disc electrode with a Kel-F holder was used in conjunction with a rotating ring-disc electrode. The resistance to localized attack is closely linked to the preanodization potential (Eox) applied in the absence of Cl- ions. For Eox below about 0.2–0.3V vs SCE, the resistance to localized attack provided by the passive film is independent of Eox; above the breakdown potential, the localized attack is manifested by the formation of pits at the mild steel surface. The breakdown potential increases linearly with NaHCO3 concentration and pH. Passive film breakdown for Eox below about 0.2–0.3V vs SCE most likely begins with a surface film dissolution prior to the penetration of the aggressive anions through the film. For Eox above about 0.3V vs SCE under the same conditions, no pitting is noticed and the potential associated with localized attack shifts considerably in the anodic direction due to interstitial (formation of crevices) corrosion at the mild steel/Kel-F interface.
    Type of Medium: Electronic Resource
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  • 5
    Publication Date: 2004-08-01
    Description: We compare rates of decay of foliar litters of British Columbia tree species in two field studies, and assess which initial litter chemistry parameters best predict the decay rates. Nutrient concentrations, tannins, and carbon fractions (based on proximate analysis and nuclear magnetic resonance spectroscopy) were measured in fresh litter of 14 tree species in one experiment and seven species in a second experiment. Each study was replicated in a different site in order to assess the transferability of results. Broadleaf litters decayed faster than needle litters only during the first year; thereafter, they decayed slower. Lignin concentration was a good predictor of mass loss only during the first year and only in one of the two experiments, which may have resulted from all foliar litters having high lignin concentrations (〉170 mg·kg1). Litter chemistry effects on first-year decay were consistent and transferable among sites. None of the initial litter chemistry parameters were good predictors of mass remaining after 4 or 5 years, because mass loss of most litters was similar by this time. The convergence in mass losses of litters after 45 years despite initial differences indicates that decomposition estimates extrapolated from early rates or initial chemistry may not accurately predict long-term decay.
    Print ISSN: 0045-5067
    Electronic ISSN: 1208-6037
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
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  • 6
    Publication Date: 2015-05-08
    Description: Single-species planting of lodgepole pine ( Pinus contorta var. latifolia ) following clear-cut logging or wildfire has been common throughout interior British Columbia, Canada, but health problems with the species have been documented as it grows beyond the juvenile stage. We examined damage and stocking in twenty-seven 15- to 30-year-old lodgepole pine plantations that were previously declared free growing in the highly productive cedar–hemlock forests in southeastern British Columbia, where lodgepole pine is absent from many primary forests. In order to be free growing, stands must meet minimum tree density, height, damage and brush competition criteria as legislated by the Provincial government. Overall, 44 per cent of lodgepole pine trees had unacceptable damage (causing them to be rejected as crop trees), and as a direct result, one-third of the plantations were no longer defined as free growing because there were insufficient crop trees remaining. Natural regeneration of other tree species partially compensated for the unhealthy pine. Logistic regression and odds ratio analysis associated increasing risk of damage from western gall rust with increasing soil moisture, more northerly aspects and mechanical site preparation, and decreasing risk with pre-commercial thinning treatment. Risk of damage from snow and ice was associated with increasing mean annual precipitation, decreasing longitude and broadcast burning. Risk of bear damage was associated with increasing soil moisture, pre-commercial thinning treatment and broadcast burning. Based on our results, we recommend that single-species planting of lodgepole pine be curtailed in the Interior Cedar–Hemlock zone in southeastern British Columbia.
    Print ISSN: 0015-752X
    Electronic ISSN: 1464-3626
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
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  • 7
    Publication Date: 1970-08-01
    Print ISSN: 0014-4754
    Topics: Biology , Medicine
    Published by Springer
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  • 8
    Publication Date: 2013-10-16
    Description: The presence of soluble carbohydrates in the cambial zone, either from sugars recently produced during photosynthesis or from starch remobilized from storage organs, is necessary for radial tree growth. However, considerable uncertainties on carbohydrate dynamics and the consequences on tree productivity exist. This study aims to better understand the variation in different carbon pools at intra-annual resolution by quantifying how cambial zone sugar and starch concentrations fluctuate over the season and in relation to cambial phenology. A comparison between two physiologically different species growing at the same site, i.e., the evergreen Picea abies Karst. and the deciduous Larix decidua Mill., and between L. decidua from two contrasting elevations, is presented to identify mechanisms of growth limitation. Results indicate that the annual cycle of sugar concentration within the cambial zone is coupled to the process of wood formation. The highest sugar concentration is observed when the number of cells in secondary wall formation and lignification stages is at a maximum, subsequent to most radial growth. Starch disappears in winter, while other freeze-resistant non-structural carbohydrates (NSCs) increase. Slight differences in NSC concentration between species are consistent with the differing climate sensitivity of the evergreen and deciduous species investigated. The general absence of differences between elevations suggests that the cambial activity of trees growing at the treeline was not limited by the availability of carbohydrates at the cambial zone but instead by environmental controls on the growing season duration.
    Print ISSN: 0829-318X
    Electronic ISSN: 1758-4469
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
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  • 9
    Publication Date: 2012-08-09
    Description: Monitoring cambial phenology and intra-annual growth dynamics is a useful approach for characterizing the tree growth response to climate change. However, there have been few reports concerning intra-annual wood formation in lowland temperate forests with high time resolution, especially for the comparison between deciduous and coniferous species. The main objective of this study was to determine how the timing, duration and rate of radial growth change between species as related to leaf phenology and the dynamics of non-structural carbohydrates (NSC) under the same climatic conditions. We studied two deciduous species, Fagus sylvatica L. and Quercus petraea (Matt.) Liebl., and an evergreen conifer, Pinus sylvestris L. During the 2009 growing season, we weekly monitored (i) the stem radial increment using dendrometers, (ii) the xylem growth using microcoring and (iii) the leaf phenology from direct observations of the tree crowns. The NSC content was also measured in the eight last rings of the stem cores in April, June and August 2009. The leaf phenology, NSC storage and intra-annual growth were clearly different between species, highlighting their contrasting carbon allocation. Beech growth began just after budburst, with a maximal growth rate when the leaves were mature and variations in the NSC content were low. Thus, beech radial growth seemed highly dependent on leaf photosynthesis. For oak, earlywood quickly developed before budburst, which probably led to the starch decrease quantified in the stem from April to June. For pine, growth began before the needles unfolding and the lack of NSC decrease during the growing season suggested that the substrates for radial growth were new assimilates of the needles from the previous year. Only for oak, the pattern determined from the intra-annual growth measured using microcoring differed from the pattern determined from dendrometer data. For all species, the ring width was significantly influenced by growth duration and not by growth rate, which differs from previous studies. The observed between-species difference at the intra-annual scale is key information for anticipating suitability of future species in temperate forests.
    Print ISSN: 0829-318X
    Electronic ISSN: 1758-4469
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
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  • 10
    Publication Date: 2013-09-03
    Description: Tree-ring chronologies of Pinus sylvestris L. from latitudinal and altitudinal limits of the species distribution have been widely used for climate reconstructions, but there are many sites within the temperate climate zone, as is the case in northeastern Germany, at which there is little evidence of a clear climate signal in the chronologies. In this study, we developed long chronologies of several cell structure variables (e.g., average lumen area and cell wall thickness) from P. sylvestris growing in northeastern Germany and investigated the influence of climate on ring widths and cell structure variables. We found significant correlations between cell structure variables and temperature, and between tree-ring width and relative humidity and vapor pressure, respectively, enabling the development of robust reconstructions from temperate sites that have not yet been realized. Moreover, it has been shown that it may not be necessary to detrend chronologies of cell structure variables and thus low-frequency climate signals may be retrieved from longer cell structure chronologies. The relatively extensive resource of archaeological material of P. sylvestris covering approximately the last millennium may now be useful for climate reconstructions in northeastern Germany and other sites in the temperate climate zone.
    Print ISSN: 0829-318X
    Electronic ISSN: 1758-4469
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
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