Seasonal Changes in Photosynthetic Characteristics of Ammopiptanthus mongolicus Study on characteristics of photosynthetic membranes in Yangmai No.5 (T.aestivum L.) flag leaves during photosynthetic functional decline process Changes in Characteristics of PS Ⅰ from Flag Leaves of Yangmai No. 5 (Triticum aesti v um L.) under Light-temperature Stress during Photo-synthetic Functional Decline Process Effects of ultraviolet-C irradiation on membrane lipid peroxidation and activity of PSⅡ electron transport in chloroplasts of Taxus cuspidata needles