简介:【背景】2,4-D二甲胺盐是一种选择内吸性除草剂,用于清除果园、牧场、水域等环境中的藜、苋等阔叶杂草。本文明确了2,4-D二甲胺盐在防除鱼塘杂草过程中对淡水鱼类的毒性。【方法】采用半静态法测试了2,4-D二甲胺盐对草鱼、鲢鱼和鲫鱼的急性毒性,并明确了2,4-D二甲胺盐对草鱼、鲢鱼和鲫鱼的安全浓度。【结果】随着供试鱼苗在药液中暴露时间的延长,LC50。值逐渐减小。2,4-D二甲胺盐对草鱼、鲢鱼和鲫鱼的96hLC50值分别为369.27、339.20和438.47mg·L^-1。2,4-D二甲胺盐对草鱼、鲢鱼和鲫鱼的安全浓度分别为36.93、33.92和43.85mg·L^-1。【结论与意义】2,4-D二甲胺盐对草鱼、鲢鱼和鲫鱼表现低毒。本研究为合理使用2,4一D二甲胺盐防除水生杂草提供了依据。
简介:Reactionsofthe6-hydroxy-thiopyrano[3,4-c]pyridine-5-carbonitrilederivative1withα-halo-carbonylcompoundsgavetheortho-substitutedintermediates2a-cwhichwereconvertedintofuro[2,3-b]thiopyrano[4,3-d]pyridines3a-cbyfusionofafuranmoietyunderbasicconditions.Furthercyclizationof3a-cledtoafusionofapyrimidinering,yieldingthetetracyclicproducts6,7and8.Inaddition,condensationof6withvariousaromaticaldehydesaffordedthecorrespondingimines9a,b.Mannichreactionof7gaveproducts10a,b.