共查询到20条相似文献，搜索用时 62 毫秒
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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… 相似文献
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<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 相似文献
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内蒙古自治区水资源可持续利用问题及对策 总被引：2，自引：0，他引：2
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。 相似文献
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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 相似文献
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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 相似文献
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丁艳 《贵阳学院学报(自然科学版)》2021,16(2):39-43,61
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... 相似文献
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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。 相似文献
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邱雪仁 《闽西职业技术学院学报》2004,6(1):79-82
节水灌溉是解决水资源短缺和促进农业可持续发展的有效途径。龙岩市新罗区在节水灌溉方面得到一定的发展,但纵观全区现状不容乐观。针对存在的问题,需要依据实际情况,对灌区进行节水工程改造,完善配套管理制度,才达到节水增效、节水增收的目的。 相似文献
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罗艳萍 《读与写:教育教学刊》2008,5(6)
The communication of people partially is the communication of cultures. Culture has a direct effect on international commercial activities in all aspects. Different conceptions about time, space, equality, law and the like, lead people to deal with things in different ways. So to know cultures of the counterpart is to facil-itate our enterprises so as to have a smooth and successful communication in commercial activity. 相似文献
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邱崇丙 《唐山师范学院学报》2014,(1):21-23
汉字的六书,《说文》对“转注”一类,语焉不详。后世学者提及转注,也仅限于许慎所举出的例字。《汉字例说》一文,作者从转注的角度综合考虑,对部分现代常用字作了分析,跟传统的解释有所不同。希望能抛砖引玉,互相切磋,以推进学术研究。 相似文献
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Richard Denner 《海外英语》2007,(4):14-15
Rosco and I wait for the fishermen to return.I sit at a wooden bench near the store at Mt.Baker Resort and watch the clouds change shape. Rosco has my belt around his neck and an eight foot tow chain hooked to a tree. Dogs must be on a leash. Ducks and rabbits are loose. 相似文献
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Given a graph G,a subgraph C is called a clique of G if C is a complete subgraph of G maximal under inclusion and |C|≥2. A clique-transversal set S of G is a set of vertices of G such that S meets all cliques of G. The clique-transversal number, denoted as TC (G), is the minimum cardinality of a clique-transversal set in G. The clique-graph of G, denoted as K (G), is the graph obtained by taking the cliques of G as vertices, and two vertices are adjacent if and only if the corresponding cliques in G have nonempty intersection. Let F be a class of graphs G such that F={G|K(G) is a tree}. In this paper the graphs in F having independent clique-transversal sets are shown and thus TC (G)/|G|≤1/2 for all G ∈ F. 相似文献
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《海外英语》2007,(5):10-11
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? 相似文献
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Rachel Zupek 《海外英语》2007,(11):40-41
我们绝大部分人都同意一件事情——我们喜欢金钱。但是你对金钱的喜欢之情足够到让你创立一份事业么?.财富通常被人忽视,主要在于人们不能真正了 相似文献
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陈美曦 《山东教育学院学报》2008,23(2):103-107
Different nations have different social cultures, and the social culture of every nation is developing with the development of the nation, language is greatly influenced by social culture, which enables language to possess national and historical characteristics. Word is the smallest, independent, meaningful linguistic unit of language. It can well reflect the national and historical characteristics. From synchronic aspect, the social and cultural influence on word meaning is mainly embodied in conceptual and associative meanings of word. The incorrespondence of word meaning is a phenomenon that exists in both conceptual and associative meanings of word among different languages. From diachronic aspect, the development of social culture causes some changes of word meaning to some extent. Therefore, social culture plays a key role in vocabulary learning and mastery of a language. 相似文献
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YANGShiguo 《重庆大学学报(英文版)》2004,3(1):86-88
The problem on the geometrc inequalities involving an n-dimensional simplex and its inscribed simplex is studied. Aninequality is established, which reveals that the difference between the squared circumradius of the n-dimensional simplex andthe squared distance between its circumcenter and barycenter times the squared circumradius of its inscribed simplex is not lessthan the 2(n-1)th power of n times its squared inradius, and is equal to when the simplex is regular and its inscribed siplex is atangent point one. Deduction from this inequality reaches a generalization of n-dimensional Euler inequality indicating that thecircumradius of the simplex is not less than the n-fold inradius. Another inequality is derived to present the relationship betweenthe circumradius of the n-dimensional simplex and the circumradius and inradius of its pedal simplex. 相似文献