Impacts of freeze-thaw processes on antioxidant activities and osmolyte contents of Syntrichia caninervis under different desert microhabitats Comparison and improvement on the extraction method for chlorophyll a in phytoplankton Soil effluxes of carbon dioxide, methane and nitrous oxide during non-growing season for four temperate forests in northeastern China Responses of soil structure to seasonal freezing-thawing in a typical black soil cultivated region. Effects of temperature on the mineralization of organic carbon in sediment of wetland