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31.
Schreier H  Shah PB 《GeoJournal》1996,40(1-2):45-51
Water is rapidly becoming a critical factor in the development of Nepal despite the fact that it has one of the greatest hydro-power potentials in the world. The country is faced with three key water issues: hazardous hydro-power development, problems with community water supply and pollution, and shortages of irrigation water. Both the environmental settings and the socio-economic conditions have contributed to these problems which are now widespread and alarming. Environmental factors have not been taken seriously as shown in the largest existing hydropower reservoir, which has recently lost much of its storage capacity in a single unusual storm. Shortages in water supplies in the capital city are also reaching crisis proportions both in terms of quantity and quality. The widespread lack of irrigation water in the Middle Mountains during the dry season has serious implications for the future food supplies of the largely rural population. Some of these problems result from a rapidly expanding population living in a very marginal environment, an ineffective government organization and an international community that is mostly self-serving, focussing on large projects with little concern for local needs. The degradation of water resources is putting the food supplies and health of a large part of the population at risk.  相似文献   
32.
一般认为大陆拉伸与火山作用是互补的,但盆岭省某些高度拉伸部分的地层和构数据却揭示出快速拉伸似乎具有受到抑制的火山作用。这一关系可能反映了在拉伸过程中由岩浆 分的出溶作用、岩浆与大气的不断作用及岩浆进入较小岩体的排出作用产生的中地壳岩 增强结晶作用。  相似文献   
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Jadh.  PB 刘永江 《世界地质》1991,10(1):117-118
斑状灰岩、石英岩和泥质岩的旋回沉积序列出露于Yadwad-Lokapur-Bagalkot地区,被命名为“Bagalkot群”(Jayaprakash等,1987),这一序列遭受了强烈的变形作用改造,形成幅度高波长短的背斜和向斜,褶皱轴均呈西-北西-东-南东到东-西向展布。尽管非强干岩石单元的比例超过了强干岩石单元,但这些单元的岩性强度差并不很大。在中型褶皱中,均匀的轴向和由正弦波状到很紧闭状褶皱样式的显著变化常常可以在灰岩,偶尔也在石英岩中见到。石英岩常常呈玻璃状,细粒结构,表面上无任何变形迹象,但是这些石英岩的详细  相似文献   
35.
台湾大南澳片岩杂岩的构造演化   总被引:2,自引:0,他引:2  
  相似文献   
36.
Metazooplankton abundance, biomass (<80μm, 200-500μm and >500μm) and community structure in the Ahe atoll were studied together with their relationships with environmental factors (temperature, salinity, wind) and trophic factors (phytoplankton, bacteria, heterotrophic nanoflagellates (HNF) and ciliates) during three periods in 2008-2009. Meroplankton, mainly bivalve and gastropod larvae, was dominant. Holoplankton was dominated by copepods, the main species being Oithona spp., Paracalanus parvus, Clausocalanus spp., Corycaeus spp., Acartia fossae and Undinula vulgaris. The results suggest a clear wind influence on the structure and horizontal distribution of the zooplankton communities. The metazooplankton appeared to be controlled mainly by food resources, suggesting a bottom-up control. The low nanophytoplankton biomass in contrast to the high abundance of picophytoplankton, HNF and nano-particle grazers (mainly Oithona spp., Paracalanus and bivalve larvae) highlighted the importance of the microbial loop in the food web.  相似文献   
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Kurt PB  Ozkoc HB 《Marine pollution bulletin》2004,48(11-12):1076-1083
A mussel and seawater monitoring survey was conducted at six sampling points between Yalikoy (Ordu) and Sinop in 1999-2000 along the Mid-Black Sea Coast of Turkey in order to assess concentrations of organochlorine pesticides (OCs) and polychlorinated biphenyls (PCBs). Chlorinated pesticides and PCBs were measured in the mussel Mytilus Galloprovincialis and in seawater. In the mussel samples, the most common pollutants in terms of average concentration per g of wet weight (ww), were DDT (max. 1800 pg/gww, min. 240 pg/gww) and its metabolites DDD (max. 5400 pg/gww, min. 240 pg/gww) and DDE (max. 2800 pg/gww, min. 70 pg/gww). Also, dieldrin, heptachlor and HCB were notable contaminants in the mussel samples. PCBs were determined in none of the biota or seawater samples. The concentrations of the OCs and PCBs in mussels were higher in coastal areas receiving river discharges and close to the largest city of the region, Samsun (especially in sampling points in the harbour area). The well-known long persistence of DDTs and other chlorinated compounds was confirmed by residues of these pollutants measured in mussels. On the other hand, even though the usage of such kind of persistent compounds in Turkey was banned, there may still be illegal usage and it is not certain whether the application of these compounds did end in the region.  相似文献   
39.
对中国川东南地区两个穿越二叠-三叠系(P/Tr)界线的关键剖面进行详细的沉积相研究,目的是进一步研究二叠纪末集群绝灭的时限和原因。在碳酸盐台地环境中高分异度的礁相和平底生物群均延续到二叠纪最后一个阶(长兴阶)末期。  相似文献   
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