沙漠化

Zhangye oasis as one of main producing area of commercial purveyance in China lies in the middle of Gansu corridor and is entitled "Golden Zhangye", But the district is circled by many dune and threaten by more and more serious desertification.

位于河西走廊中段的张掖绿洲作为我国的商品粮重镇，素有金张掖'的美称。然而在境内两大沙区数以万计的沙丘的分隔包围之下，该区又面临着严重的沙漠化威胁。

It can be used as the guidance and reference in the application of PLC to robot.First, the fact of desertification and the prevention method were introduced generally and the importance and necessity of this research was also discussed. By comparing the characteristics and application field of SCM control system, relay control system and computer control system, we selected the control scheme based on PLC.

本文首先总体介绍了我国土地沙漠化的现状和防治方法，论述了该课题研究的重要性和紧迫性，并通过对比分析单片机控制系统、继电器控制系统、计算机控制系统各自的特点及应用范围，最后确定了基于可编程控制器为核心的控制方案。

This paper gives a research on desertification and its development trend in Maqu county, using the method of romote sensing and on-spot serveying.

作者运用遥感与地面调查相结合的方法，对玛曲县的土地沙漠化及其发展趋势进行了研究。

The changing trend was induced by area fluctuation of semi-mobile and semi-fixed dunes because 2.6% area of semi-mobile dunes and 12.3% area of semi-fixed dunes were unchangeable during 1987 to 1995. And, most changeable area of the semi-mobile and the semi-fixed dunes transferred to other sand-dune types and cropland.

沙漠化程度的变换主要是由半流动和半固定沙丘的变化所导致，其中在1987-1995年期间，半流动和半固定沙丘分别只有2.6%和12.3%保持不变，其余部分主要转移成其他沙丘类型和农田。

Sandy desertification and soil salinization are two types of desertification in western Northeast Plain of China.

中国东北平原西部土地荒漠化，主要表现为土地沙漠化和土地盐碱化，它属于荒漠化的两种类型。

Land desertification is one of the most main types of land degradation in the arid and semiarid region,northern China.

土地沙漠化是我国北方干旱半干旱地区土地退化最严重的类型之一。

The social and economic sustainable development in the arid and semiarid area in China has been restricted by sandy desertification heavily.

沙漠化是制约我国干旱、半干旱地区社会经济可持续发展的重要因素。

Desertification is land degradation occurs in arid, semi-arid and subhumid regions, which is one of the he environmental problems human society generally concerned in the context of global change, has a direct relationship with the survival and development of their own humanity.

沙漠化即发生在干旱、半干旱及半湿润干旱地区的沙质荒漠化，是全球变化背景下，人类社会普遍关注的环境问题之一，与人类自身的生存和发展有着直接的关系。

Therefore, it is clear that the moisture regime is the principle factor for the land cover change in subhumid and semiarid areas of the mid-temperature zone.

定量计算表明，人类活动所导致的生态破坏在内蒙古奈曼旗50～70年代和50～90年代累计发生的土地沙漠化中所起的作用分别占38.4％和46.7％。

Modern approach methods of geography, ecology, quantitative analysis, expert integration, remote sensing image analysis and geographical information system were combined to reveal the matters in this paper. The eco-geographical background of the research area and the research work studied by other scholars were comprehensively expatiated. The temporal and spatial variation of precipitation and soil moisture, vegetation and soil distribution, and land use/land cover were compared as well. On the basis of foregoing analysis, the eco-geographical differentiation was discussed. According to principles and indicators, with extension engineering method and integrated analysis, the physical geography boundary between subhumid and semiarid areas were demarcated. By using remote sensing image analysis, wavelet analysis of the perennial precipitation and temperature, and the comparison of temporal and spatial variation of the desertification, this paper accounted for the regional response to global environmental change and suggested the dominant environmental problems.

本文采用了地理学与生态学相结合、定量分析与专家集成相结合、遥感图像解译和地理信息系统相结合的方法，对研究区的生态地理背景和已有研究工作进展情况给予了全面的分析和阐述；通过对区域水分条件（大气降水、土壤水分条件）、植被、土壤、土地利用／土地覆被状况等环境要素的时间与空间特征的对比分析，探讨了研究区内部生态地理特征的差异；在一定的原则指导下，通过建立指标体系，以可拓工程方法和模型为支撑，经过综合分析确定了研究区内半湿润、半干旱区界线划分方案；通过遥感图像解译、典型站点多年降水与温度的小波分析、土地沙漠化时空变化的对比分析等，说明了研究区域对全球变化的响应；表明了该区域所面临的主要环境问题。

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。