نتایج جستجو برای: microfossil
تعداد نتایج: 309 فیلتر نتایج به سال:
Metals are directly a n d / o r indirectly involved in all aspects of microbial growth, metabolism and differentiation. Many metals are essential, e.g. K, Na, Mg, Ca, Mn, Fe, Co, Ni, Cu, Zn, Mo, whereas others have no known essential biological function(s), e.g. AI, Ag, Cd, Sn, Au, Sr, Hg, T1, Pb. All these elements can interact with microbial cells and be accumulated as a result of physico-che...
The Neoproterozoic was an era of great environmental and biological change, but a paucity of direct and precise age constraints on strata from this time has prevented the complete integration of these records. We present four high-precision U-Pb ages for Neoproterozoic rocks in northwestern Canada that constrain large perturbations in the carbon cycle, a major diversification and depletion in t...
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