When sampling frequency is quite high, frequency spectrum distributing of digital natural sampling and natural sampling is similarity.
当采样频率比较高时，数字化自然采样法的频谱分布与自然采样法的频谱分布类似。
Methods in 1999, a cross-sectional study was carried out in a natural population of Beijing, using stratified-random sampling method.
方法1999年在北京市自然人群中采用分层随机抽样的方法进行横断面调查。
PFU can be used as a sampling method for detection of organic chloride pollutants in natural water body and concentration variety of organic chloride pollutants in continuous water body.
有机氯污染物检测结果与PFU微型生物参数变化趋势相吻合。PFU法可用于天然水体中有机氯污染物的筛选，以及连续水体中有机氯污染物浓度变化的监测。
"It's kind of obvious in retrospect," Xu said, "but sticky spider webs may be a 'natural' DNA sampling device for DNA from the spider, and from what it's been eating."
徐说，“现在回想起来好像也很显而易见，粘粘的蜘蛛网是收集蜘蛛及其食物dna的“自然”采样设备。”
Methods: Sampling was carried out in natural about water source of the Yellow River and running water in HuiNong area.
方法：对惠农地区黄河水和自来水进行采样分析。
Methods: Sampling was carried out in natural about water source of the Yellow River and running water in HuiNong area.
方法：对惠农地区黄河水和自来水进行采样分析。
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