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1.
全球变化研究是国际科学界跨世纪的重大研究主题。国际全球变化研究从其组织、计划制定与实施已逐渐形成了一套有机的完整的框架体系,整体推动着全球变化研究的深入开展。文章从国际全球变化的组织框架、计划体系和主要研究环节等主要方面概述了国际全球变化研究实施十年后的进展与现状,特别是分析概括了全球变化研究的主要环节——观测研究、过程研究、预测研究、数据与信息管理研究、影响(后果)分析研究、对策研究与政策评估研究,简明概述了其研究现状与进展  相似文献   

2.
边坡系统稳定性的可靠性研究   总被引:10,自引:0,他引:10  
论述了复杂边坡系统稳定性研究中引入可靠性理论的必要性。总结了边坡系统可靠性分析的研究内容和研究方法,其主要内容为:影响边坡系统稳定性因素的可靠性研究、可靠性计算模型的研究、边坡不稳定性空间预测的可靠性研究、边坡不稳定性时间预测的可靠性研究。分析了目前研究中存在的问题,提出了进一步研究的方向。  相似文献   

3.
边坡系统稳定性可靠性研究   总被引:4,自引:2,他引:2  
论述了复杂边坡系统稳定性研究中引入可靠性理论的必要性。总结了边坡系统可靠性分析的研究内容和研究方法,其主要内容为:影响边坡系统稳定性因素的可靠性研究、可靠计算模型的研究、边坡不稳定性空间预测的可靠性研究、边坡不稳定性时间预测的可靠性研究。分析了目前研究中存在的问题,提出了进一步研究的方向。  相似文献   

4.
现代港口地理学的研究进展及展望   总被引:7,自引:0,他引:7  
基于港口地理研究的时代背景变迁,分析了现代港口地理学的研究进展与研究内容,重点从港口地理的基本研究范畴、港口理论、港口体系、枢纽港、港口与腹地关系、航运网络、航运企业和码头企业等角度深入解析其重点历程与主要论点,对中国港口地理学的研究进展和国际学者的相关论点进行了阐述,然后从研究内容、研究范式、研究重点和研究地区等角度,总结和评价现代港口地理学的研究特征,梳理其发展规律与研究轨迹。同时基于以上研究,从研究范式、研究重点、研究单位等角度,对港口地理学的未来研究趋向进行了深入探讨。通过该研究,系统总结了港口地理学的研究进展,有助于该学科的理论和实证研究。  相似文献   

5.
该文论述了古生态学的性质与内涵,回顾了我国古生态学的发展过程,介绍了近年来的研究状况,并对今后古生态学的发展趋势和任务诸如门类古生态学的宏观研究、遗迹化石学、化石的化学性质物理性质的微观研究、定量古生态学研究、天文古生态学研究、群落古生态学的综合研究等做了探讨。  相似文献   

6.
国际科学跨世界的重大研究主题   总被引:4,自引:1,他引:4  
张志强 《地学前缘》1997,4(2):255-262
全球变化研究是国际科学界跨世纪的重大研究主题,国际全球变化研究从其组织、计划制定与实施已逐渐形成了一套有机的完整的框架体系,整体推动着全球变化研究的深入开展,文章从国际全球变化的组织框架、计划体系和主要研究环节等主要方面概述了国际全球变化研究实施十年后的进展与现状,特别是分析概括了全球变化研究的主要环节--观测研究,过程研究、预测研究、数据与信息管理研究、影响(后果)分析研究,对策研究与政策评估研  相似文献   

7.
全球变化研究进展和趋势   总被引:13,自引:2,他引:13  
-概述了国际全球变化研究计划(ESSP、IGBP、WCRP、IHDP、DIVERSITAS)新近的研究战略调整和研究重点,在对国际全球变化研究成果综合分析的基础上,总结了全球变化研究的阶段性理论进展,归纳了全球变化研究的特点和趋势。  相似文献   

8.
季节性冻融期土壤入渗试验综述   总被引:4,自引:0,他引:4  
杜琦 《地下水》2009,31(2):14-16,44
2004~2005年山西省水文水资源勘测局太谷均衡实验站和太原理工大学合作进行了《不同地表条件下季节性冻融土壤入渗特性的试验研究》。详细地介绍了此项目研究的意义、研究的现状、研究的内容、野外试验方案及研究结果,并对研究结果进行了述评。  相似文献   

9.
概要论述了地质微生物学、地下水微生态学、微生物地球化学作用的基本概念、研究内容、研究现状、科学意义、关键问题、发展前景和在地下水环境保护中的作用。该研究领域不仅拓宽了整个地质科学的研究范畴,而且推动了地质科学的发展,具有一定的创新性。  相似文献   

10.
概要论述了地质微生物学、地下水微生态学、微生物地球化学作用的基本概念、研究内容、研究现状、科学意义、关键问题、发展前景和在地下水环境保护中的作用.该研究领域不仅拓宽了整个地质科学的研究范畴,而且推动了地质科学的发展,具有一定的创新性.  相似文献   

11.
Four new Trichoptera species: Kliganigadukia taymyrensis gen. et sp. nov. (Hydrobiosidae), Archaeopolycentra yantardakh sp. nov. (Polycentropodidae), Taymyrodipseudon protopegasus gen. et sp. nov. (Dipseudopsidae), and Siberoclea parapolaria gen. et sp. nov. (Leptoceridae) from Late Cretaceous amber (Santonian, Kheta Formation, 85 Ma) of Taymyr (Siberia, Russian Federation) are described and illustrated. Data on the Cretaceous amber Trichoptera (13 families, 20 genera, 29 species) are summarized and discussed.  相似文献   

12.
Most of the rocks in Precambrian shield areas have experienced a complex structural and metamorphic evolution, processes which have a strong influence on bedrock quality. The properties vary on both a local and a regional scale. It is highly beneficial to know the variations in detail when exploiting the rocks for industrial purposes. The main objective of the investigation was to study the variation of rock mechanical properties in an originally more or less isotropic rock at various stages of ductile deformation. The rocks investigated were Paleoproterozoic and with ages of ca. 1.80-1.88 Ga, and the areas chosen for sampling were situated north-east of Lake Vänern (Kristinehamn; 10 samples), south of the city of Eskilstuna, South Central Sweden (5 samples) and south of Ödeshög, near Lake Vättern in southern Sweden (7 samples). The 12 samples from the latter two areas are described in this investigation, while the 10 samples from Kristinehamn have been published earlier (Göransson et al., 2004). A comprehensive study of various parameters of importance for bedrock quality has been performed on all samples, e.g. studded tyre test (STT) and Los Angeles test (LA), uniaxial compressive strength (UCS), ultrasonic velocity, perimeter measurements of mineral phases, and petrographic and chemical analyses. The weakly deformed and massive (more or less isotropic) rocks show a tendency towards better properties of abrasion (STT) than the strongly deformed rocks and this can also be said for UCS, reflecting the greater ability of rocks to split along foliation planes. This is not entirely unambiguous, as the more deformed rocks, such as the mylonites, may have varying properties. This depends on the combined effects of, e.g. grain size, recrystallisation and foliation. However, the brittleness (LA) shows somewhat better values with increased deformation. This may depend on higher amounts of dark minerals, as their existence does not affect this test as much as in the case of abrasion tests. The perimeter values of the mineral phases display generally higher values, i.e. grain boundaries for the more strongly deformed rocks are more complicated. However, the values for the investigated mylonites may vary between low and high. The lower value may be due to dynamic recrystallisation and the creation of triple points (static recrystallisation) making the rock weaker. Besides, the development of a strong foliation may decrease rock strength despite the usually finer grain size. The results show that it is extremely important to consider all possible variations of bedrock before classification and exploitation, as the bedrock material in fact is highly heterogeneous.  相似文献   

13.
The study of the schists from Lotru valley (Carpathians mountains, Romania) shows the role of stress in graphite crystallinity. The carbonaceous material was separated and studied by X-ray diffraction and Raman microspectrometry. There exists a clear contrast between the crystallization degree of graphite found in the quartz–muscovite schists (good) and that found in the quartzites (poor). This observation is in conformity with a clear differentiation of fabric. The graphite suffered an anisotropic deformation in the graphitic schists, whereas it was protected from deformation by quartz in the quartzites. In this last case, the development of graphite from the organic material took place with a volume decrease, protected by the surrounding quartz. To cite this article: S.-C. Barzoi, B. Guy, C. R. Geoscience 334 (2002) 89–95.  相似文献   

14.
ABSTRACT Estuarine sediments commonly form major sinks for contaminants released during industrial activity. Many industrial processes lead to the release of metals initially in solution, which can then be adsorbed on to, for example, Fe hydroxides or clay minerals. However, in the mining industry, there are two major contaminant waste streams: (1) metals discharged in solution via mine drainage; and (2) particulate grains of the ore‐forming or related minerals released after ore processing. The release of particulate waste can have a major long‐term impact on environmental geochemistry. In this study, we have mapped the distribution of arsenic, copper, tin and zinc within the surficial sediments of the Fal Estuary, Cornwall, UK, an area that drains a historically important polymetallic mining district. There are clear spatial variations in the contaminants, with the highest levels (> 2800 p.p.m. As, > 5000 p.p.m. Cu, > 3000 p.p.m. Sn and > 6000 p.p.m. Zn) within Restronguet Creek on the western side of the estuary. Mineralogical studies show that small (< 20 µm) grains of detrital arsenopyrite, chalcopyrite, cassiterite and sphalerite are very abundant within the surface sediments. Most of the sulphide grains are fractured, but mineralogically unaltered, although some grains show alteration rims caused by oxidation of the sulphides. The geochemistry and mineralogy are indicative of sediment supply from the discharge of particulate waste into the estuary during historical mining activity. Subsequently, this particulate waste has been largely physically and biologically reworked within the surface sediments. Although considerable effort has been made to minimize contaminants released via mine drainage into the estuary, the potential flux of contaminants present within the intertidal and subtidal sediments has not been addressed. Benthic invertebrates living within the area have adapted to be metal tolerant, and it is likely that the dominant source of bioavailable metals is a result of alteration of the particulate mine waste present within the intertidal and subtidal sediments.  相似文献   

15.
Abstract: Sn, B and Pb-Zn skarn, vein and disseminated deposits occur in the eastern part of Sikhote-Alin fold system associated with the late Cretaceous-earliest Paleogene volcano-plutonic complexes, which are products of a continental margin-type subduction along the East Sikhote-Alin belt. There are two metallogenic zones where the ore deposits are concentrated. The Taukha metallogenic zone combining B and Pb-Zn skarn, vein and disseminated deposits occurs on the main volcanic chain along the Japan Sea coast. Late Cretaceous-earliest Paleogene calc-alkaline plutonic and volcanic rocks of magnetite series predominate here. Volcanic rocks overlie on the lower Cretaceous Taukha terrane which consists of abundant olistostromes with numerous olistoliths of Triassic limestones. During the middle-late Cretaceous time, an ignimbrite erupted and formed a huge borosilicate skarn deposit. A later subduction related volcanism of the late Cretaceous-earliest Paleogene stage (70–55 Ma) was predominated by andesites and rhyodacites. Many Pb-Zn skarn and vein deposits were formed. Sulfur isotope compositions of galena in the B and Pb-Zn deposits of the Taukha metallogenic zone vary from –1. 3 to +2. 0%, averaging 0% in the δ34S.  相似文献   

16.
The autochthonous magnesian carbonates and the gypsum depicted in the Holocene deposits from the ‘Marais de Sarliève’ (Limagne, France) result from an alkaline, magnesian and sulphated composition of waters. This is also recorded by the composition of algal micro- and macrophytes. This may be explained by the dissolved fluxes from the Oligocene catchment and from a restriction. During the historical period, the lake evolved towards a lesser restriction. To cite this article: J.-G. Bréhéret et al., C. R. Geoscience 335 (2003).  相似文献   

17.
The applanation of mountain belts that results in peneplain is generally considered to be caused by the long-term activity of erosion. Peneplanation has been previously defined as the lowering of an elevated topography and the concomitant subduing of its relief. We propose a model following which piedmont sedimentation induces the base level rise, allowing applanation to develop at high elevation and resulting in an elevated ‘peneplain’. This model is illustrated by the morphological evolution of the southern flank of the Pyrenees during the Cainozoic. To cite this article: J. Babault, J. Van Den Driessche, C. R. Geoscience 337 (2005).  相似文献   

18.
Calcite samples were extracted both from the rock matrix and the superficial coating of a karstified fault plane of an underground quarry, located in the eastern border of the Paris basin. The karstification is dated as Quaternary. Analysis of mechanical calcite twinning reveals that only the calcite matrix has also undergone a compression trending WNW that can be attributed to the Mio-Pliocene alpine collision. Both coating and matrix have undergone a strike-slip regime with σ1 roughly trending north–south, that could correspond to the regional present-day state of stress, a strike-slip compression rather trending NNW, modified by local phenomena. To cite this article: M. Rocher et al., C. R. Geoscience 335 (2003).  相似文献   

19.
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   

20.
The Henchir El Yahoudia landfill is one among many uncontrolled dumping sites in Tunisia with no bottom liner. It is located at the southeastern edge of Sijoumi Sebkha. The site has been exploited since 1963 until 1994. It constitutes a peculiar case because of its situation, its exploitation mode and the nature of buried wastes. Leachate analysis shows that they are strongly charged with nitrogen (especially ammoniacal and kadjedahl), organic compounds with a high biodegradability and a charge of metallic elements exceeding the Tunisian norm NT 106-002. Sediment analyses show that the highest rate of heavy metals and organic matter coincides with clay-richest layers, characterized by the highest specific-surface values. The percolation of these pollutants until the groundwater between 0.5 and 5 m has provoked a pollution characterized by high rates of organic matter (BOD, COD and nitrogen) and heavy metals. To cite this article: A. Marzougui, A. Ben Mammou, C. R. Geoscience 338 (2006).  相似文献   

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