排序方式： 共有39条查询结果，搜索用时 31 毫秒
21.
阿克苏市日照时数的突变检测分析 总被引：14，自引：0，他引：14
运用气候突变理论对阿克苏市日照时数序列进行检测分析，结果发现近50年阿克苏市年日照时数总体呈增多趋势，但其间存在两次突变。在1980年前后年日照的突变现象显著，表现为日照时数的急剧减少，主要是由于11、12月日照时数的突然变少引起的；90年代初的突变则从80年代的气候少日照阶段转变成多日照阶段。 相似文献
22.
从我国洁净煤技术展望煤田地质勘探 总被引：2，自引：0，他引：2
通过分析我国能源的消费结构,认为煤炭是今后相当长一段时间内的重要能源,但目前仍然存在着燃煤技术落后、环境污染的问题。因此,必须大力开展洁净煤技术研究。这样要求煤田地质勘探必须运用新技术进行盆地分析、煤田预测,探明适合于洁净煤技术的煤炭资源,进行煤层气的资源评价,开展煤系地层中微量元素的含量及分布规律研究,为煤炭开发、能源综合利用、环境保护提供可靠信息。 相似文献
23.
Coastal aquifers are subjected to natural seawater intrusion. Laboratory experiments were made to model the hydraulic conditions of saltwater inflow into a porous karstic conduit through which the freshwater flows. The conceptual model is based on the functioning scheme of the coastal karst system Almyros of Heraklion, Crete. The experiments show that seawater intrusion in a karst conduit can be diffuse, does not always lead to density separation of freshwater and seawater, and is not necessarily related to a conduit-network directly connected to the sea. To cite this article: B. Arfib, J. Ganoulis, C. R. Geoscience 336 (2004). 相似文献
24.
主要从工程设计、地质条件、施工工序、质量检测等几个方面全面介绍了塑性混凝土防渗墙在长江重要堤防加固工程的施工技术应用。其中重点阐述了工序中施工工艺部分，包括地质补充勘探、定位放线、导墙制作、泥浆质量控制、泥浆管理、成槽工艺、清渣换浆、水下混凝土浇注、单元连接及接头处理等关键分部工程的施工方法。 相似文献
25.
受自然条件及人类活动的影响,地下水环境发生了较大的变化,地下水污染问题日益引起广泛的关注。正确确定背景值对地下水污染评价十分重要。以收集的松嫩平原哈尔滨地区150余组地下水水化学样品分析数据为依据,在分析区域流场、补给径流条件的基础上,选用数理统计法和经验法求取了研究区潜水和承压水地下水环境背景值,并对地下水环境背景值进行比较。结果表明:数理统计法以自然地理环境和人类长期活动的综合作用为基础,克服了经验法的不足,可较真实地反映研究区地下水背景状况;研究区内潜水中指标NO3-、Fe、Mn和承压水中指标Fe、Mn均为高背景值指标;区内地下水环境背景值与人类活动、地下水的补、径、排和沉积环境条件具有密切的关系。 相似文献
26.
A new biostratigraphic correlation for Late Cretaceous and Palaeocene strata of the Côte d’Ivoire–Ghana continental margin has been developed from the identification of significant dinoflagellate cyst events in ODP Hole 959D. The Late Cretaceous stage boundaries are mostly consistent with previous studies. However, the Maastrichtian/Danian boundary is placed much lower than previously recognized on the basis of the first occurrences of Carpatella cornuta and Damassadinium californicum. The base of the Selandian is recognized from the last occurrence of Cerodinium diebelii and the first occurrence of Adnatosphaeridium multispinosum. The base of the Thanetian is recognized from the first occurrence of Areoligera gippingensis. The rarity of the age-marker taxa is the main reason for different age determinations among studies of the same section. 相似文献
27.
Biodiversität und Ökologie aquatischer Oomycetes‐Arten im Auesee und in der Fulda in Kassel (Hessen)
Biodiversity and Ecology of Species of Aquatic Oomycetes in the Aue Lake and the River Fulda in Kassel (Hessen) In this study, we record diversity and ecology of aquatic Oomycetes in the Aue Lake and the river Fulda in Kassel (Hesse, Germany). We monthly collected water samples of both water bodies from July 2003 to June 2004. The baiting method was used to gain an insight into the occurrence of aquatic Oomycetes. A total of 14 species of aquatic Oomycetes belonging to the orders Saprolegniales, Leptomitales and Olpidiopsidales could be isolated of both water bodies. Numerous saprophytic isolates of Rhizophydium Schenk (Chytridiomycetes), Rhizophydium carpophilum (Zopf) Fischer, parasitic on Oomycetes, and additionally one species of Plasmodiophoromycetes, Woronina polycystis Cornu could be isolated. Many isolates of Saprolegniales attributable to the genera Achlya Nees, Dictyuchus Leitgeb, Saprolegnia Nees and Pythium Pringsheim (Pythiales), which could only be identified on generic level, could be isolated as well. The species were examined and discussed with respect to their occurrence in the stagnant water Aue Lake and/or in the running water of the river Fulda. Half of the isolated species only occurred in one of the water bodies. In this study the occurrence of Achlya proliferoides Coker could be documented for Germany for the first time. The trophic status of the Aue Lake and of the classification of water quality of the river Fulda were determined by limnological‐chemical parameters obtained by simultaneous investigations of both water bodies. 相似文献
28.
THOMAS J BASSETT 《The Geographical journal》2005,171(1):24-35
This paper examines wildlife decline in northern Côte d'Ivoire with emphasis on the political-economic and cultural dimensions of market hunting. Hunting and the trade in wild animal meat are situated within the economic diversification strategies of impoverished farmers and the flourishing of hunter associations. The role of hunter associations is critical in the rise in the number of hunters and firearms in the case study area of Kakoli. Initiation into the national hunters' association, Binkadi, allows card-carrying members to bear arms without legal repercussions. Higher quality arms and rural poverty motivate many of these recruits to engage in market hunting. Game market surveys for 1981–82 and 1997–99 in Kakoli show tremendous pressure on both vulnerable and robust species alike. Game depletion is conceptualized as the outcome of interacting social and biophysical processes that produce hunting pressure and habitat change. By drawing attention to the political-economic, ecological, and cultural dimensions of wildlife decline, this study implicates a diversity of actors and institutions in the dynamics of game depletion. 相似文献
29.
运用2001年12月20-29日在昌吉热电厂区进行的低空探测资料，重点分析了该地区大气边界层风和温度层结的垂直分布特征，获得了该地区污染气象特征的初步结果。 相似文献
30.
新化高桥玄武质富钛古火山岩研究 总被引：1，自引：0，他引：1
高桥玄武质火山岩是一个化学成分独特的富钛基性火山岩。属震旦纪海底喷发的拉斑玄武岩,化学成分以富含TiO_2、MgO、Fe_2O_3+FeO特征。本文通过多方论证后指出:伴生的变辉绿岩属火山颈相,Ti的富集是蚀变作用的结果。 相似文献