The reasons can cum up to following aspects, negative influence of market economy, unhealthy thoughts in sociality, trend of iniquity and phenomenon of corruption, distempered physical education system, weakness of collegians themselves and so on.

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Through the implementation of stubble to field operations,it can curb this unhealthy trend and will continue increase soil fertility, and create good conditions for agricultural production.

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The paper reviewed the host selection mechanisms and rules of xylophagous insects and their application foreground in forest health evaluation. According to the rule that some secondary xylophagous insects always accompany with trees which are sub-healthy or unhealthy, ideas of diagnosing and evaluating forest health betimes using xylophagous insects were posed. Mathematical models would be established based mainly on interactions between quantity of xylophagous insect populations and status of forest health, interspecific interactions (community structure, biodiversity) and environmental factors were also added as supplementary parameters, in order to quantitatively analyzing and comprehensively evaluating forest health and its developing trend.

本文綜述了蛀干昆蟲對寄主植物選擇機(jī)制和規(guī)律的國內(nèi)外研究進(jìn)展及其在森林健康評價(jià)中的應(yīng)用前景A片免费看看看看看看看看看看，根據(jù)蛀干昆蟲中次期性種類總是與亞健康和衰弱林木相伴的規(guī)律，提出了利用蛀干昆蟲早期診斷和評價(jià)森林健康的思路欧美AAAAAAAA片一级，以蛀干昆蟲種群數(shù)量與林木健康狀況的相互關(guān)系為主日韩午夜无码播放器视频，輔以物種間相互作用關(guān)系、環(huán)境因子等建立數(shù)學(xué)模型免费观看亚洲黄片，定量分析和綜合評價(jià)森林健康及其發(fā)展趨勢日夲一级黄色视频。

market unhealthy：市場不穩(wěn)定

market trend 市場趨勢 | market unhealthy 市場不穩(wěn)定 | marketing 市場學(xué)