高Zn^2＋对蒜根的毒害及Ca^2＋的解毒效应

用不同浓度（１００～４００ｍｇ／Ｌ）的Ｚｎ（ＮＯ３）２和Ｚｎ（ＮＯ３）２＋Ｃａ（ＮＯ３）２溶液处理蒜鳞茎发现：高Ｚｎ＾２＋对蒜根有毒害作用,随浓度增大和处理时间延长,细胞有丝分裂指数下降,而核异常细胞比率先升（１００～３００ｍｇ／Ｌ）后降（４００ｍｇ／Ｌ）,在Ｚｎ＾２＋中加入Ｃａ＾２＋,能提高细胞有丝分裂指数,降低核异常细胞比率,变化总趋势与单Ｚｎ＾２＋类似,但核异常细胞比率一直上升。此结果表明适量的Ｃａ＾２＋对Ｚｎ＾２＋的毒害有一定的缓解作用。     

A Simplified Method to Calculate the Wet Bulb Globe Temperature(WBGT)

Wet bulb globe temperature(WBGT) is a comprehensive index obtained mainly from three pa-rameters:black globe temperature(Tg),wet bulb temperature(Tw),and dry bulb temperature(Ta).While in field observation and numerical simulation,black globe temperature and wet bulb temperature were not easy to obtain, so WBGT was difficult to measure and calculate directly.In order to solve this problem,air dry bulb temperature, wet bulb temperature,globe temperature,relative humidity,mean air velocity,solar radiation and wet bulb globe temperature were collected during the summer(July)in Guangzhou.Correlation analysis and regression analysis were used to get a simplified method to calculate WBGT.The results showed that dry bulb temperature,relative humidity,solar radiation and WBGT were interrelated to some extent.These three pa-rameters could be used in the simplified method to predict WBGT,and the linear correlation and precision of this model were high.In addition,we used the measured data to verify the simplified method,and the results showed that the error of the calculated value and the measured value was all below 5%,which means the simpli-fied calculating method is feasible and can be used in field observation and simulation research of urban thermal environment.