نتایج جستجو برای: trace element
تعداد نتایج: 263901 فیلتر نتایج به سال:
Primitive, low-silica and high-alkali magmas that erupt late in the evolution of most ocean island volcanoes are highly enriched in incompatible trace elements, yet their isotopic compositions require a time-integrated mantle source history of incompatible-element depletion. Reconciling these observations has traditionally required either extremely low degrees of partial melting of depleted man...
Ž . We report Inductively Coupled Plasma Mass Spectrometer ICP-MS trace element concentration data for 21 elements in Ž 51 basaltic glasses recovered from 58 stations along a 1500-km segment of the equatorial mid-Atlantic Ridge MAR; 58N to . Ž 58S . Isotope systematics of these glasses revealed mixing between two isotopically distinct Schilling, J.-G., Hanan, B.B., McCully, B., Kingsley, R.H., ...
UNLABELLED Biological trace elements are required for numerous biological processes and by all organisms. We describe a database, dbTEU (DataBase of Trace Element Utilization), that features known transporters and user proteins for five trace elements (copper, molybdenum, nickel, cobalt and selenium) and represents sequenced organisms from the three domains of life. The manually curated dbTEU c...
Most imbalances of trace-element nutrition are characterized by the absence of acute, easily recognizable disease. To diagnose marginal deficiencies or excesses of trace elements, the analyst must use rather sophisticated procedures, and even where an imbalance of trace-element nutrition can be proven, the implications for health are not always evident. Previous attempts to connect deviations o...
Each of two calcitic stalagmites from Grotte de Clamouse, Herault, southern France, displays a discrete aragonite layer dated at around 1100 yr BP. The layer of fanning aragonite ray crystals is immediately preceded by calcite with Mg and Sr compositions that are uniquely high for the past 3 kyr. Trace element compositions close to the boundary between original aragonite and calcite are consist...
We evaluate the mid-term effects of two amendments and the establishment of R. officinalis on chemical and biochemical properties in a trace element contaminated soil by a mine spill and the possible use of this plant for stabilization purposes. The experiment was carried out using containers filled with trace element polluted soil, where four treatments were established: organic treatment (bio...
Intestinal absorption and excretion are the main regulatory mechanisms for maintenance of body homeostasis of most trace elements. In spite of considerable research on trace element metabolism in man and experimental animals, the knowledge about the mechanisms involved in these processes is still limited. The characteristics of trace element metabolism, such as low fractional absorption, the pr...
Modern trace element research is concerned at present with 17 elements, the essentiality of which has either been established or is suspected. Even when we concentrate on the seven or eight elements for which problems of deficiency or excessive exposure are known to occur in man, the multitude of their individual metabolic pathways, requirements, and interactions with the environment represents...
We performed an ion-microprobe study of eleven high-MgO (6.7±14.8 wt%) tholeiite glasses from the Hawaiian volcanoes Kilauea, Mauna Loa and Ha-leakala. We determined the rare earth (RE), high ®eld strength, and other selected trace element abundances of these glasses, and used the data to establish their relationship to typical Hawaiian shield tholeiite and to infer characteristics of their sou...
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