Investigation on the Degradation of Natural Heritage of Singing Sand Mountain and Crescent Moon Spring at Dunhuang City, China

The main purpose of this study is to put forward a reasonable idea of the general protection for Singing Sand Mountain and Crescent Moon Spring, a rare and unique desert wonder, and of sustainable tourism development based on the research on the ecological environment around. Methods of documentation, case study and comparison were employed. Finally, aiming at solving the problems of natural environment and those existing after the exploitation of Singing Sand Mountain and Crescent Moon Spring the author puts forward three measures： the comprehensive treatment for Crescent Moon Spring （broadening resources of water and reducing expenditures, checking the decreasing depth of Crescent Moon Spring, and improving the geographical environment）, the general protection envisions for Singing Sand Mountain and Crescent Moon Spring and establishing a dynamic monitoring and early-warning system of regional ecosystem.     

谨防坐位性肌力衰退

国内外调查资料表明，长期处于坐位工作状态的人，其肌力下降的现象较为显，而且随着工作年限的延长有进行性加重的趋势。     

武汉东湖水生植被现状调查及群落演替分析

对东湖水生植物的调查结果表明，东湖现存水生维管束植物共计20科25属33种，其生物量约为1.137t，分布面积仅占东湖总面积的0．7％，其中挺水植物分布面积占总面积的98％。与1957年、1962～1963年和1988～1994年相比，东湖水生植物的种类、分布面积和生物量进一步减少。认为造成东湖水生植被衰退的主要原因包括富营养化作用加剧、过度放养草食性鱼类和人类活动的影响。     

Sonocatalytic degradation of methyl orange in the presence of (nanometer and ordinary) anatase TiO2 powders

The nanometer and ordinary anatase titanium dioxide(TiO2 ) powders were adopted as the sonocatalysts for the degradation of methyl orange used as a model compound for the first time. It was found that the sonocatalytic degradation effect of methyl orange in the presence of TiO2 powder were much better than that without TiO2, but the sonocatalytic activity of the nanometer anatase TiO2 particle was obviously higher than that of ordinary anatase TiO2 particle. Although there are many factors influencing sonocatalytic degradation of methyl orange, the experimental results showed that the best degradation ratio of methyl orange could be obtained when the experimental conditions were: initial concentration 15 mg/L, nanometer anatase TiO2 adding amount 750 mg/L, ultrasonic frequency 40 kHz, output power 50 W, pH = 3.0 and temperature 40℃ within 150 min. In addition, the catalytic activity of reused nanometer anatase TiO2 catalyst was also studied and found to decline gradually comparing with initial nanometer anatase TiO2 catalyst. All experiments indicated that the method of the sonocatalytic degradation of organic pollutants in the presence of TiO2 powder was an advisable choice for non-or lowtransparent organic wastewaters.     

光波炉的原理与危害

<正>许多消费者在购买的时候就知道其用处,那它对人体又有哪些危害呢,下面小编为您详细介绍。光波炉的原理要了解光波炉的危害,首先我们就需要看下光波炉原理,目前市场上的光波炉大概就分为三种:一种就是在普通微波炉里面加入了光波作为加热来源和微波共同加热食物的"光波微波炉",光波微波炉外形和普通的微波炉没有什么区别。     

夏秋一绝马齿苋

人到中年,各系统机能开始出现程度不同的衰退现象,接踵而来的就是难以名状的不适感觉。如果您步入中年,若能对自己的身体加以注意,经常察看“钟”与“表”,可防患于未然,避免积重难返的大病发生。其“钟”与“表”的内容是：     

Degradation characteristics of two Bacillus strains on the Microcystis aeruginosa

IntroductionManykindsofalgaecanleadtowaterbloomandredtideintheseas ,lakesandreservoirs .Thisphenomenoninfluencesorchangesthephysicalandchemicalcharacterofwaterandthenresultsinmanytroubleinthedrinkingwaterproductionprocess(Hargensheimer,1996;Graham ,1997;M…     

关于森林衰退与大气污染关系的研究概述

大气污染对森林的生长发育具有巨大的影响。自１９世纪中叶以来,世界上许多科学家对这方面问题进行了大量卓有成效的研究。内容涉及污染症状的诊断,污染源的追踪控制,主要污染物在不同的树种上极限浓度的确定,主要污染物质的空中化学转化过程以及酸雨和森林衰退的原因等许多方面。本文对这方面的研究作一综述。１各国对森林衰退的研究１９世纪中叶,德国科学家施德克哈特（ＳｔｏｅｃｋｈａｒｄｔＪ．Ａ．１８５０）发现,位于一熔炼厂附近的森林（欧洲赤松Ｐｉｎｕｓｓｙｌｖｅｓｔｒｉｓ，挪威云杉ｐｉｃｅａａｂｉｅｓ）生长不良,并推断是…     

混交林的改土效益及其在防止地力衰退上的应用

讨论了人工混交林对林地土壤理化性质、微生物及水土保持等方面的改良和促进作用。针对目前人工纯林地力衰退的问题，提出了混交林可作为防止地力衰退的途径， 并对混交林应用上的有关问题作了探讨。