雨水集流——灌溉农业的新思路

到2000年,我国粮食产量要达到4.9—5.0亿吨,扩大农田灌溉面积是实现这一目标的重要措施。但我国是水资源缺乏、水利用率较低的国家,开辟新水源和提高水利用率等是发展灌溉农业的关键所在。建国以来,我国农田灌溉面积发展到7.2亿亩,农业灌溉年用水量约4000亿立方米,是头号用水“大户”,必须通过对广大半干旱地区水的开发来扩大灌溉面积。我国发展灌溉农业面临的问题和我国发展灌溉农业的迫切性,要求我们在开发水源和提高水利用率上要有新的思路和技术。雨水集流灌溉技术是在人工创造集水工程(集水面、集水池等)的基础上,配套实施简便高效的滴…     

谈北方干旱地区的合理灌溉

<正>我国是一个水缺乏的国家。长期面临着用水短缺的制约,是我国北方干旱地区农业生产的一个显著的特征。干旱的连年发生,给农业生产和群众生活造成了严重影响。对于这样的农业大国,理所当然是用水大户。而且我国水资源利用率较低,有很大的节水开发潜力。如何使有限的水资源得到有效利用,用来提高农业生产的利用率,来满足生产较多的粮食、蔬菜和水果等农产品,大力推广农业节水增效灌溉技术是缓解水资源紧缺的根本出路,更是是提高农业综合生产能力,确保农业可持续发展的必然     

内蒙古自治区水资源可持续利用问题及对策

本文分析了气候变化和人类活动对内蒙古水资源的影响以及未来50年淡水资源的供需矛盾。指出,90年代水资源的紧张主要不是由气候变化所造成,而是人类活动的结果。因此,必须控制农业灌溉用水总量,大力推行节水灌溉。否则将严重制约二、三产业的发展。提出通过开发空中资源、提高降水利用率、改善植被动态增加土壤水多种途径和措施,保障21世纪内蒙古水资源的可持续利用。     

21世纪中国水资源展望

一、我国水资源的概略分析 水利是农业的命脉,也是农业发展的主要制约因素。我国是一个12亿人口的大国,年产粮食49 250万吨(1997),居世界首位,基本达到粮食自足;我国也是一个水资源大国,据1980年的统计数据,总用水量4440亿m~3,目前已超过5556亿m~3,大致与美国相当,是世界上用水量最大国家之一,农业灌溉用水与农业灌溉面积,均居全球前列。没有水就没有粮食,由此可见中国是一个水资源比较丰富的国家,否则就不可能生产出养活     

水及物质的构成学习指要

一、自然界的水1.水污染.主要起因:工业排放大量污水;农业上大量使用农药、化肥;生活污水的任意排放.我国人均水量少,许多地区水资源严重短缺,我们要爱护水资源,一方面要节约用水,另一方面要防止水污染.节水措施主要是提高水的利用率,使用节水器     

晋南节水农业潜力分析

晋南地区是全国水资源最匮乏的地区之一。发展节水农业是实现农业持续高效发展的重要途径。根据晋南地区的特点，应主要在提高水分利用率、生产率和农业用水管理水平上下功夫。     

甘肃省农业节水的主要措施和技术路线

甘肃省水资源的利用中,农业用水、工业用水、生活用水分别占总用水量的80.31%、14.11%和5.58%.由此可见,甘肃省节水的重点应该是农业,即提高农业用水的效率.因而必须以学科交叉性的重大前沿性技术研究为出发点,研发与农业节水相关的重要关键技术,探索建立适合本国国情、本地实际的现代节水农业技术体系.     

农业经济发展和环境污染的联立方程模型构建研究

我国水资源缺乏,农业经济发展主要受到水资源制约,鉴于此,本次研究将构建农业经济发展与环境污染的联立方程模型,并从水污染的角度探究环境污染对农业经济发展的影响.实验结果表明,农作物单产受到工业废水排放量、化肥用量、废水治理成本的影响;污水灌溉降低农作物产量,致农作物严重受损,如农作物产量的降低、农作物中污染物含量超标、农...     

晋中东部节水灌溉发展思路的讨论

晋中东部是传统的农业县,种植业是主要产业,近几年的持续干旱使农业生产损失巨大,发展节水灌溉势在必行。本文从产业结构调整、水资源合理利用、节水灌溉工程、农业节水和节水管理方面论述了节水灌溉发展的思路。     

浅析农田水利节水灌溉

介绍我国水资源现状和农业用水状况,通过分析节水灌溉的发展趋势,指出了在我国农业节水灌溉的现状和推广中出现的问题,并针对出现的一系列问题,并提出了相应的对策.     

卡思卡特城堡

It is worthy of noting that, whilst Crookston Castle witnessed the earlier and happier portion of Mary's variegated life,     

不同的吃喝玩乐

一、吃和喝吃苹果 eat an apple, 吃药 take medicine,吃糖 have some sweets,吃饭 have one's meals,吃馆子 dine out,吃惊 be surprised/     

漏洞百出的教育

Many college freshmen arrive woefully unprepared to do college work, and as disadvantaged populations continue to grow, the share of the American work force that has made it through college is expected to plummet. Many experts blame that educational failure not just on high schools but also on colleges. School & College, a special report by The Chronicle, looks at efforts to fix the system. What reforms would better prepare students for college? What should schools and colleges be doing differently? How should state and federal officials help?     

只要努力,不要后悔

There are numbers of crossroads on our long and unpredictable life journey where we totally have no idea about which direction to choose. No matter what our decision is, we should not turn back, but face the music and go ahead instead. I am this kind of girl who always does try without regretting, one example is how I dealt with my love.     

浅谈移民问题

Migration occurs behind a variety of reasons and has a great effect on the whole world. People may migrate in order to improve their economic situation, or in order to escape civil strife, persecution, and environmental disasters. The impact of migration is complex, bringing both benefits anddisadvantages. This paper briefly talks about the causes of migration, the allocation of benefits, and the ways in which individual countries and the international community deal with this important subject.     

Sister Carrie, an Adherent of Desires

Sister Carrie is one of the most controversial characters in American literature.Thought as a "fallen woman" firstly,she was defined as a "new woman" by some critics later. However, by digging into the motivaton behind the whole process of Carrie's "success", the relationship between Carrie and her creator (the author), the social conditions of then American, it can be found that Carrie has never been free-standing on her thought and she has never found her real-sdf even after becoming a famous actress. In a society dominated by mass consumerism Carrie is only an adherent of her own desires. She also is a representative of all those country girls flooded into cities, a symbol and a sacrifice of the urbanization of America in a time countryside was overcome by cities.     

Improvement of one-cycle controller by use of proportional integral differential controller

1.IntroductionOne-cyclecontrolmethod,whichwasproposedaboutonedecadeago[1],hasbecomeanattractivemethodinspecialfieldssuchaspowerfactorcorrection[2-6],switchingamplifiers[7,8],etc.Themainideaofthiscontrollerisbasedonintegrationofdiodevoltageinone-cycleandforcesittobeexactlyequaltothereferencevalue.Themainadvantageofthiscontrollerisitsrealtimeabilitytorejectthevariationofinputvoltage[1].Despitethisgreatability,ithasnogoodperformancesinrejectingofloaddisturbanceandfollowingreferencecommands.Espec…     

库克斯顿城堡

城堡, 是欧洲典型的建筑之一, 每个城堡都有一个美丽的传说或是一段历史。从本期开始, 我们将推出“城堡之旅”, 带各位读者去浏览、观赏欧洲各地的城堡, 开始一段文化与历史的旅途!     

The Reader Response Approach to Teaching of English Literature

During interview with English majors, it was found that a majority of students expressed disappointment with their experience of English literature classes. Students' dislike of learning English literature appears to be the major problem of teaching English literature in China. Reader response approach is a good way to solve this problem. In this paper, I explain the rationale behind the reader response approach, such as its origin, definition, features, assumptions, and strategies. Then I illustrate how reader response approach works as a teaching strategy by presenting several teaching models. At last I evaluate its usefuiness for teachers and present the advantages of reader response approach in Chinese context.