初中区域地理分组学习评价

随着以教师为中心的传统教学向以学生为主体的现代教学观念的转变,地理教学方式也在发生巨大的变化,合作学习已经受到越来越多教师的关注和学生的欢迎。在初中地理教学中,不少教师非常乐于采用小组合作一探究教学模式,当然也有教师对这样的教学方法心存质疑,他们认为学生分组学习的评价比较难操作。那么,初中区域地理分组学习评价目前存在的问题是什么？是什么原因造成了如今的评价现状？如何评价才能推进新课程背景下教学方式和学习观念的转变？     

世界矿产勘查预算及趋势报告

2004年世界勘查预算概况　全世界的勘查预算从1997年反弹到目前历史最高水平.根据金属经济组织第15版的联合勘查战略（CES,被公认为全世界勘查、采矿、统计信息的最重要来源的报告）,世界范围内的商业性非铁金属勘查预算已经连续两年上升,反弹到比1998年的勘查预算数略高的一个水平.2004年38亿美元的预算总数比2003年增长了58%,为勘查预算低谷期2002年总数的两倍.     

Nudging地面加密观测改进数值模式对城市效应及其触发对流的模拟:一次夜间个例试验

城市(热力、动力、人类活动等)效应对城市及周边地区强降水有着重要的影响。由于涉及到多方面因素,在数值模式中合理描述城市效应仍然存在许多困难。采用Nudging地面加密观测间接引入城市效应(Nudg)和使用城市冠层模式直接引入城市效应(Urba)两种方式模拟了2017年5月7日发生在广东广州的一次极端降水过程。结果表明Nudging地面加密观测能够有效地在数值模式中引入城市效应,从而合理地再现出城市热岛及其触发的对流和强降水的时空演变,而使用城市冠层模式未能够模拟出城市热岛及其触发的对流和降水。具体而言,Nudg能够维持城市的热岛,在城市热岛的下风方最先触发了对流,对流快速发展并稳定维持,从而在广州城市下风(西北)方形成了强降水。然而,Urba试验中城市热岛迅速减弱消亡,从而未能在城市下风方触发出对流,导致降水模拟的失败;尽管后期在城市下风方边缘及北部山区有零星的雷达回波,但均未能够发展形成组织化的对流单体或系统。对本次强降水事件对流的触发而言,城市热岛的加热作用较城市的摩擦辐合更重要。提出的Nudging地面加密观测间接地引入城市效应的方法可用于与城市下垫面相关的各类天气事件的模拟研究。      

2006年夏季塔中一次沙尘暴发生期问近地层气象特征个例分析

利用塔克拉玛干沙漠大气环境观测试验站的两种前向散射能见度仪(CJY-1C和FD12)2009年6月14日-8月5日的探测数据和人工目测数据对各种天气下的能见度变化进行了对比分析.结果表明,FD12和CJY-1C型能见度仪数据有很好的一致性.在能见度较低时,FD12型能见度数据与平均值偏离程度最小,测量更加稳定.FD12型能见度仪数据更接近于目测能见度数据.对于两种能见度仪,两者在扬沙天气的相关性最好,浮尘天气下的相关性较好,沙尘暴天气次之,典型晴天下的相关性最小,可在监测浮尘和扬沙天气时互相替代使用.     

塔克拉玛干沙漠腹地沙丘温度特征浅析

塔克拉玛干沙漠腹地沙丘温度因不同类型、深度、部位、天气、时段差异很大。利用不同深度、部位,晴天和沙尘天,裸地与植被,不同植被下的温度观测,浅析其温度分布特征。沙丘表面日最高温出现在顶部,日最低温和日较差最大值出现在迎风坡。沙丘顶部和迎风坡升温快,降温也快,日较差大,落沙坡则相反。沙丘顶部、左翼、迎风坡和落沙坡,日变化振幅,浮尘、扬沙天小于晴天。迎风坡和落沙坡20cm深度,晴天和沙尘天最高最低温度出现时间和沙表层有相反趋势。0～20cm迎风坡和落沙坡日较差逐渐减小,最高与最低温度出现时间,晴天和沙尘天不同,晴天和沙尘天温度差值在白天较大。裸地和植被表层沙面温度变化较大,植被阴面日变化振幅小于裸地和植被阳面。裸地和植被浅层温度变化平缓。红柳和芦苇所在沙堆表层温度日变化较大,梭梭的日变化小,温度最低值均出现在07时。     

Migration and the transformation of employment and household structures

Data collected in Colombia and Thailand in 1977 are used to "compare the employment and household characteristics of migrants before and after the move in order to assess the degree of change which accompanies migration. Moreover, these comparisons [are] made for migration streams between places at different levels in the urban hierarchy with the intention of determining within which streams the greatest transformations occur."     

Population trends and the status of population policy in Africa

There is every indication that Africa's population growth will remain well above the world average for the remainder of this decade and probably for the rest of this century. With the exception of the island states and parts of North Africa, fertility levels show little indication of change. This is in part a reflection of little desire for small families, as well as a consequence of limited or even restricted family planning services. Great diversity in attitudes regarding population policy prevails among African governments, ranging from extreme pronatal to committed antinatal. Even with antinatal policies, however, many African states have yet to attain any significant success in depressing their rates of growth. To date, Mauritius can be cited as the only state to have almost achieved the transition from high to low fertility. The consequence of these continuing trends is that Africa will see further increases in its youth dependency ratio. Pressures on infrastructural services will therefore increase, and the problems of generating employment will intensify. While demographic factors are by no means the only ones creating economic stress on the continent, they clearly are contributory. Unlike Asia or parts of Latin America, Africa's problem is less a matter of too many people but rather 1 of excessive growth in too short a time frame. A realistic and effective long-term population policy, therefore, is an immediate need. Several countries including Nigeria (with a pouplation of over 80 million) are experiencing a crude birth rate of 50 or more/1,000. At least 4 countries, including Kenya, are currently doubling their population in 20 years or less. With these current population trends, a demographic transition to low vital rates must assume passage through an even higher growth phase than is currently being experienced because the fall in birth rates tends to occur much later than the fall in death rates. Government population policies and the status of family planning activities are illustrated according to natal sentiments and attitudes. Trends in national vital rates and of population structures in Africa are illustrated.     

Molecular and isotopic analyses of the hydroxy acids, dicarboxylic acids, and hydroxicarboxylic acids of the Murchison meteorite

The hydroxymonocarboxylic acids, dicarboxylic acids, and hydroxydicarboxylic acids of the Murchison meteorite were analyzed as their tert-butyldimethylsilyl derivatives using combined gas chromatography-mass spectrometry. The hydroxydicarboxylic acids have not been found previously in meteorites. Each class of compounds is numerous with carbon chains up to C8 or C9 and many, if not all, chain and substitution position isomers represented at each carbon number. The alpha-hydroxycarboxylic acids and alpha-hydroxydicarboxylic acids correspond structurally to many of the known meteoritic alpha-aminocarboxylic acids and alpha-aminodicarboxylic acids, a fact that supports the proposal that a Strecker synthesis was involved in the formation of both classes of compounds. Isotopic analyses show these acids to be D-rich relative to terrestrial organic compounds as expected; however, the hydroxy acids appear to be isotopically lighter than the amino acids with respect to both carbon and hydrogen. The latter finding would not be expected if both classes of compounds came exclusively from common precursors as would have been the case for a Strecker synthesis.     

地热资源及其开发利用

一、地热资源概述地球的深部蕴藏着巨大的热能。在地质因素的控制下,这些热能会以热蒸汽、热水、干热岩等形式向地壳的某一范围聚集,当在当前技术经济和地质环境条件下能够科学、合理地开发出来利用时,便成了具有开发意义的地热资源。     

遥感技术在四川省生态环境遥感综合调查中的应用

在研究调查全省范围各生态环境因子、要素的基础上，首次建立了四川省综合生态环境分析系统，并完成了四川省生态环境区划。通过遥感调查进一步印证、明确了四川生态环境存在的主要问题是水土流失及地质灾害，它们影响甚至破坏了四川东部的生态环境。提出了建立盆缘生态环境保护圈的意见。