我国水资源的开发利用

水是人类赖以生存和发展的物质基础之一，随着人口的增长和社会经济的发展，人类对水资源的需求在不断增长，供需矛盾日渐尖锐。我国多年平均水资源总量为2．81244X1012m3，占世界第六位，人均占有量为2527m3／人，不到世界平均值的1／4，名列88位。水资源不丰富，时空分布不均，致使水荒问题已严重制约着我国社会经济的发展。中国，已被列为世界28个缺水国之一。本文就我国水资源问题发表一些看法。——我国水资源开发利用的历史极为悠久，从大禹治水开始，水利即成为安邦治国之本。象郑国渠、引漳十二渠、智伯渠、都江堰、灵渠、京杭大运…     

21世纪水荒冲突将加剧

在21世纪，水荒将引发政治紧张、小冲突甚至战争，正如石油在本世纪后半叶的影响一样。据世界银行消息，世界上80多个国家、40%的人口处于严重的用水短缺之中，水荒危及农业、工业和人类健康。人口增长、工业发展、过量灌溉用水及水污染所造成的用水短缺，不仅影响那些干旱国家，而且也影响像中国、美国这样的水资源丰富国家。     

山岳型旅游地水资源合理利用与保护探讨

水是山岳型旅游地重要的构景资源，同时也是维持山地生态平衡、满足旅游业用水的一个基础性资源。山岳型旅游地因其独特的水环境特征，在旅游开发的过程中，水环境破坏现象普遍。目前，水资源利用中存在的问题主要有两方面：一是水资源的过度利用；二是水资源的污染。根据现存的问题及其产生的原因，针对性地提出了水资源合理利用和保护的一些对策．首先确定合理的可用水量；再节约用水和充分利用景区外的水资源；采用新型污水处理技术；并注意植树造林，保护水源。     

为什么要实施南水北调工程?

我国是人均水资源十分短缺的国家，人均占有的水资源为2500立方米（每年），仅为世界人均值的1/4，而且南方水多，北方水少，汛期降雨集中，非汛期干旱少雨。我国北方的黄河、淮河、海河流域工农业发达，人口稠密，而人均占有的水资源仅为500立方米（每年），是全国人均值的1/5，世界人均值的1/20。随着这一地区经济、社会的发展，人口的膨胀，对水的需求量不断增加，使得水资源供需矛盾日益尖锐。目前我国黄淮海地区许多河流断流，湖泊水库干涸，地下水位大幅度下降，愈演愈烈的水荒已经严重制约了当地经济和社会的发展。尤其是去年我国北…     

浅谈水利工程水费经营性改革

我国水资源严重缺乏，节约用水迫在眉睫。由于水利工程设施陈旧、水价政策不到位、制度不完善、用水意识落后等原因，导致水的利用率非常低。针对这些问题，必须加强引导，建立合理水价形成机制和管理体制；健全财会制度，构建水费核算体系；提高认识，强化管理，推动供水商品化进程。     

在生物学教学中开展环境教育的探索与实践

人类面临着严重的生态危机:全球气候变暖、酸雨、生物多样性锐减、资源和能源消耗过快、土地沙漠化严重、水资源缺乏和水污染严重等。目前全世界约有11亿人口生活在空气污染严重的城市中。预计到2050年,世界人口的13%~20%将面临严重水荒。全球已有900万公顷土地寸草不生,12亿公     

我国水资源危机及其对策

我国水资源危机及其对策刘玉兰，吴金财一、我国水资源危机的主要表现１．水资源紧缺，供需矛盾日益加剧（１）人均水资源少。虽然我国的水资源总量约有２．８×１０１２ｍ３，居世界第６位；但人均水资源占有量只有２３４０ｍ３，仅为世界人均量的１／４，加拿大的１／５...     

我国的水资源问题及其可持续利用对策

我国是一个缺水的国家，随着社会经济的发展，我国的水资源问题越来越严重，已成为制约社会经济发展的“瓶颈”．实施可持续发展战略，水资源的可持续利用是重要一环，本文论述了我国水资源的四大特点及其开发利用中存在的问题，提出了七项可持续利用对策．     

中国水资源可持续利用的研究

在分析我国水资源的分布特点及存在的突出问题基础上，提出了转变陈旧的农业用水方式，建立节水型农业；转变高质生活用水方式，大力倡导中水利用；保护水源，防治水污染等水资源可持续利用的对策。     

黄河流域水资源开发利用研究

在总结和分析1972年以来黄河流域水资源利用的基础上，从自然地理因素和人类活动因素两个方面探讨了黄河流域水资源不足与供需矛盾的原因，提出了合理开发利用黄河流域水资源的基本原则．并提出了提高水价、统一调度两点对策。     

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,     

Western and Eastern culture differences in commercial field

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.     

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.     

风的曲线

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.     

团图为数的图中的闭团贯数

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.     

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.