沙漠化

Global warming, destroying of ozonosphere, desertization, acid rain and other environmental problems are not any problems of one country because these problems have threatened fundament for survival of all lives on the earth.

在我们身边发生的地球温暖化及臭氧层破坏、沙漠化、酸雨等地球环境问题不再是某一个国家的问题，如今已经成为威胁到地球上所有生物赖以生存的根本的问题。

There are a series of ecological environment problems in different areas of the Tarim river basin.

新疆塔里木河流域受人类活动的影响，特别是由于水资源利用的不合理，不同区域出现了一系列生态环境问题，下游地区普遍存在的沙漠化现象表现得尤为突出。

The level of feed-water and drain system is comparatively high in the history of China.The research on the level of agriculture in Han dynasty indicates that the prosperity of cities in Han dynasty is based on the tender agriculture and the food supplies import is a constant state in the study area. There is no breakthrough in level of agriculture after Han dynasty,and it is an important reason that the city development in the study area is fluctuant in the history of China.From the end of Han dynasty to North and South dynasty,the climate change made the cold and arid weather keeping in the study area,and affected badly the agricultural outputs.The mode of land-use was transformed from the agriculture to the nomadism in this stage.The climate change made the desertization develop mightily and fast,and approach the scale of modern time in the study area in the North and South dynasty.

研究区汉代农业生产水平的综合分析表明，一方面，汉代城市的繁荣是建立在比较脆弱的农业基础上的，粮食等物品不断的外部输入是一种常态，汉代以后很长时间粮食生产水平并没有突破性的提高，这是研究区城市发展呈阶段性起伏的重要原因；另一方面，南北朝时期冷干气候的持续，对脆弱的农业生产具有重大影响，农业向牧业迅速转化，城市的区域农业支持系统受到严重影响，该时期沙漠化也强烈发展。

According to the clear water experiment, aeration performance of the new equipment is good with high total oxygen transfer coefficient and oxygen utilization ratio.

曝气设备的动力效率在叶轮转速为120rpm～150rpm时取得最大值，此时氧利用率和充氧能力也具有较高值。

The environmental stability of that world - including its crushing pressures and icy darkness - means that some of its most famous inhabitants have survived for eons as evolutionary throwbacks, their bodies undergoing little change.

稳定的海底环境─包括能把人压扁的压力和冰冷的黑暗─意谓海底某些最知名的栖居生物已以演化返祖的样态活了万世，形体几无变化。