Abstract : this is a report of undergraduate students ' vacation activity . water samples weretaken from their homecities along the two rivers , then analyzed in university laboratory . comparing the present data of water quality with the historical ones , the importance and urgencyof envionmental protection and administration , as well as the continuative developmentare verified 文摘:报道家住长江、黄河沿江城镇的大学生在假期中对采集的水样进行分析，并将结果与积累资料作了比较，从而验证和认识了环境防治及可持续发展的重要性与紧迫性。
Abstract : according to the continuative condition of the tangential fields on the slot aperture which is the inclined narrow - slot on the broadwall of a sectoral waveguide , the moment method is used to calculate the magnetic current coefficient and distribution . then the scattering field , the scattering parameter and the equivalent impedance are obtained . leting only the te11 dominant mode propagates in the waveguide , the scattering parameters and the normalized equivalent series impedance in the x - band are computed . the basis disigned the slot antenna and the slot array is offered 文摘:根据缝隙口面切向场的连续条件，采用解析数值法矩量法，对扇面波导宽壁上窄的斜缝进行了计算，解得了磁流系数及其分布，并得到散射场、等效散射参量及等效阻抗等重要参数.假定波导中仅有te11主模传输，在x波段计算了散射参量和归一化等效串联阻抗，给出计算结果，为缝隙天线和缝隙阵列设计提供了依据
