【简答题】For large-scale separations, thick sheets of chromatography filter paper are available (Whatman No. 3 or 3mm) and these will cope with several milligrams of material per sheet.
【单选题】Naturally occurring wildfires—usually started by lightning strikes—are good for the forest. They are often small—they don't burn much forest, and they don't get too hot. These small fires actually pro...
【单选题】Changes in regional climate brought about by large-scale deforestation in the eastern lowlands of Central America are affecting weather downwind in the mountains, imperiling ecosystems there. The so-c...