北京地区渗灌条件下冬小麦田间土壤水分动态及节水机理的研究

根据对渗灌条件下冬小麦田间土壤水分、冬小麦生长发育状况及产量的观测 ,研究了渗灌条件下冬小麦田间土壤水分动态及节水机理。试验结果表明 ,渗灌条件下田间土壤水分动态变化与灌溉、冬小麦生长发育状况及气象条件密切相关 ;渗灌用于冬小麦灌溉可以明显起到节约灌溉用水的作用 ,并有利于冬小麦的生长发育及产量形成。在冬小麦的整个生育期 ,采用渗灌比喷灌田间耗水量减少了44 4mm ,灌溉用水节约了1200m3/hm<sub>2sub> ,而最终产量提高了714kg/hm<sub>2sub> ,渗灌条件下作物水分利用效率为21 11kg/(hm<sub>2sub>·mm) ,比喷灌条件下高4 49kg/(hm<sub>2sub>·mm)。渗灌用于冬小麦灌溉的节水机理主要表现为两个方面 :①每次灌溉后 ,地表湿度较喷灌条件下要小得多 ,减小了土壤水分的无效物理蒸发 ;②渗灌利于冬小麦根系向地中供水层 (20～120cm )延伸 ,提高了冬小麦根系对灌溉供水层的水分利用     

栀子黄色素对小鼠血脂代谢的影响

目的 探讨扼子黄色素对高脂膳食小鼠血脂水平的影响.方法 将30只小白鼠随机分为三个组：对照组,高脂模型＋扼子黄色素组、高脂模型＋柠檬黄组（0.2、0.5 mg/g体重）,喂养180 d后,眼球采血测定血清TC、TG、MDA含量.结果 扼子黄色素组血清MDA、TC、TG升高幅度较高脂模型＋柠檬黄组明显减少.结论 扼子黄色素对高脂膳食致血脂升高有阻抑作用.表2,参6.     

Acute toxic effects of phenanthrene on Chinese mitten crab Eriocheir sinensis北大核心CSCD

Phenanthrene is a persistent organic pollutant frequently found in aquatic environments. This paper aimed to assess the acute effects (96 h) of phenanthrene on Chinese mitten crab (Eriocheir sinensis), a key economic aquatic animal in China. An acute semi-static toxic test was carried out to expose E. sinensis to water-borne phenanthrene with different concentrations (1.00, 1.63, 2.65, 4.31 and 7.00 mg L-1) for 96 hours. Mortality and toxic reactions were used as effect criteria. Furthermore, the oxidative stress relative biomarkers (activities of CAT, SOD, GST and content of MDA in hepatopancreas and gills) were measured for E. sinensis exposed to four lower concentrations of phenanthrene (1.00, 1.63, 2.65 and 4.31 mg L-1). The median lethal concentration (LC50) for 24,48 and 96 hour phenanthrene exposure was 16.7, 2.96 and 2.14 mg L-1, respectively; and the safe concentration (SC) of phenanthrene on E. sinensis was 0.214 mg L-1. Phenanthrene significantly increased the activity of CAT in hepatopancreas and gills, and showed a significant dose-effect relationship in hepatopancreas. Bell-shape response patterns were found in the activities of GST and SOD in the hepatopancreas and gills, with significant increases of hepatopancreas GST at 1.00 and 1.63 mg L-1 (P < 0.05), and a significant decrease at 4.31mg L-1 (P < 0.05). Phenanthrene significantly increased the contents of gills MDA at 2.65mg L-1 and hepatopancreas MDA at all four concentrations of phenanthrene. Phenanthrene, especially of high concentration, is highly toxic on E. sinensis, causing lipid peroxidative damage and even acute mortality. Meanwhile, E. sinensis can adapt to lower concentrations of phenanthrene by increasing the activities of SOD, CAT and GST. Because the CAT and GST activities of the gill and hepatopancreas are very sensitive to the presence of high-concentration phenanthrene, they can be used as highly sensitive biomarkers for phenanthrene polluted water.