نتایج جستجو برای: Fossil
تعداد نتایج: 25461 فیلتر نتایج به سال:
Embryos have been found in ‘old’ rocks on four continents, especially in Siberia, Nevada, Australia and China. They have been discovered in sedimentary rocks of even Late Neoproterozoic age, assuming the evolutionary geological column1 (figure 1). The Neoproterozoic is the period, so called, between 1 billion and 550 million years ago. This discovery was in the Doushantuo Formation, Guizhou Pro...
it is inferred from the symmetrical and luminous x-ray emission of fossil groups that they are mature, relaxed galaxy systems. cosmological simulations and observations focusing on their dark halo and inter-galactic medium properties confirm their early formation. recent photometric observations suggest that, unlike the majority of non-fossil brightest group galaxies (bggs), the central early-t...
In this paper, we study the environmental consequences of fossil fuel extraction. In our model, there is a cartel of fossil fuel suppliers and a coalition of fossil fuel buyers. The cartel maximizes her profits without taking into account the negative environmental externalities of her productions. However, since consumers are suffered by environmental emissions of fossil fuels, the coalition i...
fossil fuel power plant is one of the most important sources of environmental pollution of the vanadium toxic metal. this survey showed that the penicilium austuranium is the best microorganism for biosorption of vanadium isolated from environment of fossil fuel power plant. to determine the optimum ph and most biosorption and accumulation of vanadium by these fungi, power plants wastewater, pa...
Johan Lindgren introduces fossil pigments.
Also known as... ancient DNA. The New Shorter Oxford Dictionary offers the precise explanation of ‘ancient’ as ‘belonging or pertaining to the period before the fall of the Western Roman Empire in AD 476.’ DNA can be recovered from fossils much older than 1500 years, but the inevitable time-dependent decay of the DNA structure due to oxidation and hydrolysis makes retrieval increasingly difficu...
Over the last three decades, the fossil record of spiders has increased from being previously biased towards Tertiary ambers and a few dubious earlier records, to one which reveals a much greater diversity in the Mesozoic, with many of the modern families present in that era, and with clearer evidence of the evolutionary history of the group. We here record the history of palaeoarachnology and ...
During the past century, fossil fuels--petroleum liquids, natural gas and coal--were the dominant source of world energy production. From 1950 to 2005, fossil fuels provided 85-93% of all energy production. All fossil fuels grew substantially during this period, their combined growth exceeding the increase in world population. This growth, however, was irregular, providing for rapidly growing p...
During the past century, fossil fuels—petroleum liquids, natural gas and coal—were the dominant source of world energy production. From 1950 to 2005, fossil fuels provided 85–93% of all energy production. All fossil fuels grew substantially during this period, their combined growth exceeding the increase in world population. This growth, however, was irregular, providing for rapidly growing per...
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