Management of n in agricultural ecosystem is one of the most essential factors for agricultural sustainability . injudicious use of nitrogen fertilizer has induced a crucial environmental problem , which includes volatilization of nox to the atmosphere , acid rain , induced leaching of soil nutrients , changes in the global n cycle , and nitrate pollution of groundwater 农田生态系统中长期单一、过量偏施化学肥料特别是化学氮肥，造成农产品品质下降，肥料利用率低，不仅增加了农业生产成本，还严重污染环境，已成为农业可持续发展的一个重要制约因子。
Driver fatigue is subdivided into the fatigue of vision , audition , estimate , operation , and worsen of reaction , notice . the paper also deals with driver fatigue in some given conditions . the testing technology of driver fatigue is discussed and applied 结合驾驶危险状态和驾驶模式的分析，把驾驶行为不同阶段的疲劳状态细化为视觉感知疲劳、听觉感知疲劳、速度判断疲劳、反应能力降低、注意品质下降、驾驶操作疲劳等；探讨了具体环境下的驾驶疲劳；对驾驶疲劳进行了实验测试。
It is a serious issue that water and nitrogen input rates are unreasonable high in vegetable production in china , which may increase nitrate accumulation in vegetable and ground water contamination . in result , these will be harmful to people ' s health . the objectives of this paper which based on column % pot and micro - plot experiments were to compare the effects of different water and nitrogen supply strategies on nitrogen leaching in the soil profile and nitrate accumulation in vegetable as a base for the n and water recommendations in vegetable production 针对蔬菜生产中水氮投入过量造成蔬菜品质下降、地下水硝酸盐含量超标，水、肥资源的浪费以及给人体健康造成的潜在性威胁的实际情况，以油菜和芫荽为研究对象采用模拟土柱、盆栽和田间微区试验相结合方法系统监测了蔬菜生育期内硝酸盐含量的动态变化以及收获后不同土层土壤硝态氮的残留量，研究了水氮对蔬菜硝酸盐累积的影响及对土壤硝态氮残留的效应。
