该文从能量守恒观点出发，讨论了副面为椭圆的环焦天线的口径场分布，并导出了计算其方向图的简单表达式。
The aperture field distribution of the ring focus antenna is reviewed in view of the energy conservation law, and the simple formula for calculating its radiation pattern is deduced.
结果正常人多焦视网膜电图振幅在第一环处反应密度最高，随着离心度增加，反应密度值逐渐降低；
Result The average response density of multifocal electroretinogram in normal subjects was the greatest in the first ring and gradually decreased with the increase of eccentricity.
研究表明，煤中多环芳烃通过焦化作业以烟尘、煤粒、焦末以及外排废水形式迁移而污染大气、土壤和水环境。
The study results indicate that PAHs in soot, coal particles, coke particles and waste water emitted from coking can result in the atmospheric, soil and water pollution.
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