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  • 1
    Electronic Resource
    Electronic Resource
    Fluxes of carbon, water and energy over Brazilian cerrado: an analysis using eddy covariance and stable isotopes (1997)
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 20 (1997), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: We present the energy and mass balance of cerrado sensu stricto (a Brazilian form of savanna), in which a mixture of shrubs, trees and grasses forms a vegetation with a leaf area index of 1·0 in the wet season and 0·4 in the dry season. In the wet season the available energy was equally dissipated between sensible heat and evaporation, but in the dry season at high irradiance the sensible heat greatly exceeded evaporation. Ecosystem surface conductance gs in the wet season rose abruptly to 0·3 mol m−2 s−1 and fell gradually as the day progressed. Much of the total variation in gs was associated with variation in the leaf-to-air vapour pressure deficit of water and the solar irradiance. In the dry season the maximal gs values were only 0·1 mol m−2 s−1. Maximal net ecosystem fluxes of CO2 in the wet and dry season were –10 and –15 μmol CO2 m−2 s−1, respectively (sign convention: negative denotes fluxes from atmosphere to vegetation). The canopy was well coupled to the atmosphere, and there was rarely a significant build-up of respiratory CO2 during the night. For observations in the wet season, the vegetation was a carbon dioxide sink, of maximal strength 0·15 mol m−2 d−1. However, it was a source of carbon dioxide for a brief period at the height of the dry season. Leaf carbon isotopic composition showed all the grasses except for one species to be C4, and all the palms and woody plants to be C3. The CO2 coming from the soil had an isotopic composition that suggested 40% of it was of C4 origin.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-3040.1997.d01-80.x
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  • 2
    Electronic Resource
    Electronic Resource
    An explanation of 13 C/ 12 C variations in tree rings (1982)
    [s.l.] : Nature Publishing Group
    Nature 297 (1982), S. 28-31 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Variations in the 13C/12C ratio in trees are examined in the light of a simple expression relating the relative isotope composition of plant material, δp13 to δa13, the atmospheric isotope value, ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/297028a0
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  • 3
    Electronic Resource
    Electronic Resource
    Recent 13 C/ 12 C trends in atmospheric CO 2 and tree rings (reply) (1981)
    [s.l.] : Nature Publishing Group
    Nature 293 (1981), S. 680-680 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] FRANCEY REPLIES-Freyer suggests that the Tasmanian 13C/12C tree-ring results1 do not constitute grounds for doubting the interpretation of his own (mostly Northern Hemisphere) data2, in terms of global atmospheric CO2 behaviour. In my view the Tasmanian 13C/12C records are only one of several ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/293680a0
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  • 4
    Electronic Resource
    Electronic Resource
    Synchrotron Emission from the Galaxy and the Diffuse X-ray Background (1969)
    [s.l.] : Nature Publishing Group
    Nature 224 (1969), S. 1090-1093 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The galactic radio spectrum at these frequencies is usually explained as synchrotron emission from cosmic ray electrons in the galactic magnetic field. A differential electron energy spectrum of the form dne dtf0^-1 (2) will give rise20 to a radio spectrum as in equation (1) with ? = m-1 / ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/2241090a0
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  • 5
    Electronic Resource
    Electronic Resource
    Climatic implications of stable carbon isotopes in tree rings (1976)
    [s.l.] : Nature Publishing Group
    Nature 260 (1976), S. 771-773 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Five-year blocks were taken from two King Billy pines (Arthrotaxis selaginoides D. Don) which grew within 200m of each other in natural forest in mountains of northern Tasmania (Fig. 1). A total of 71 separate burns were made on the 25 5-yr blocks of one tree and the CO2 from each burn analysed at ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/260771a0
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  • 6
    Electronic Resource
    Electronic Resource
    Tree-ring carbon-isotope ratios re-examined (1988)
    [s.l.] : Nature Publishing Group
    Nature 333 (1988), S. 712-712 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] SIR-The tree-ring 13C/12C ratio has been used as an indicator of historic climate and/or atmospheric composition despite the difficulties in interpreting the results due to other competing effects. Stuiver and Braziunas' have reported a (5!3C gradient in 1850 tree ring cellulose (from conifers). ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/333712a0
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  • 7
    Electronic Resource
    Electronic Resource
    Changes in oceanic and terrestrial carbon uptake since 1982 (1995)
    [s.l.] : Nature Publishing Group
    Nature 373 (1995), S. 326-330 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] We employ a simplified version of the global carbon and 13C budgets developed by Tans et al.4, to explore changes in d(δ13C)/ d/, where t is time. The budget relies on the fact7 that the product of total carbon and its isotopic ratio (Cxδ13C) is a conservative quantity in the ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/373326a0
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  • 8
    Electronic Resource
    Electronic Resource
    Tasmanian tree rings belie suggested anthropogenic 13 C/ 12 C trends (1981)
    [s.l.] : Nature Publishing Group
    Nature 290 (1981), S. 232-235 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Freyer's statement requires qualification. There is evidence2,4,7,9 of a levelling or an increase in 13C/12C ratios after 1940, moreover the period before 1860 is poorly sampled, thus the statistical significance of a modern trend over several decades is difficult to assess. The Freyer's conclusion ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/290232a0
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  • 9
    Electronic Resource
    Electronic Resource
    A Strong X-ray Source in the Vicinity of the Constellation Crux (1967)
    [s.l.] : Nature Publishing Group
    Nature 215 (1967), S. 38-40 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Two identical X-ray detection systems were included in the payloads of two Skylark rockets flown from Woomera, Australia (lat. = 30-9 S., long. == 136-5 E.), at 0032 U.T. on April 4, 1967 (Skylark SL 426), and at 2236 U.T. on April 20, 1967 (Skylark SL 425). The X-ray experiments on both nights ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/215038b0
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  • 10
    Electronic Resource
    Electronic Resource
    Variability of Centaurus XR -2 (1967)
    [s.l.] : Nature Publishing Group
    Nature 216 (1967), S. 773-774 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The data were obtained by X-ray detectors flown on two Skylark rockets, launched from Woomera at 0032 UT on April 4, 1967, and 2236 UT on April 20, 1967, and from an experiment1 flown from Hawaii by the Levermore Research Laboratory (LKL) group on May 18, 1967. The Skylark results have been ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/216773a0
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