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131.
Socio-economic development in Europe has exerted increasing pressure on the marine environment. Eutrophication, caused by nutrient enrichment, is evident in regions of all European seas. Its severity varies but has, in places, adversely impacted socio-economic activities. This paper aims to evaluate the effectiveness of recently adopted policies to reduce anthropogenic nutrient inputs to European seas. Nitrogen and phosphorus budgets were constructed for three different periods (prior to severe eutrophication, during severe eutrophication and contemporary) to capture changes in the relative importance of different nutrient sources in four European seas suffering from eutrophication (Baltic Proper, coastal North Sea, Northern Adriatic and North-Western Black Sea Shelf). Policy success is evident for point sources, notably for P in the Baltic and North Seas, but reduction of diffuse sources has been more problematic.  相似文献   
132.
大型铜多金属矿床地球化学异常评价指标的量化研究   总被引:2,自引:2,他引:0  
刘崇民  李应桂  史长义 《物探与化探》2000,24(4):241-245,249
集20多个铜、多金属矿床的区域、矿带(田)、矿床不同比例尺的地质、地球化学勘查资料,研制了定量评价大矿异常的地球化学方法。在系统研究不同规模多种勘查尺度地球化学异常特征的基础上,初步总结了评价大型矿床的地球化学量化评价预测指标。  相似文献   
133.
黄铁矿型铜多金属矿床是与海底火山喷发—沉积建造有关的火山岩矿床,矿化赋存于一套微量元素总体含量水平较高的海相中酸性细碧角斑岩系中。赋矿地层、岩性具有以Cu,Pb,Zn为主,伴生Sb,Ba,Ag,As,Bi,Hg,Cd等多元素的特征组合,这些元素在成矿区域上形成大范围的地球化学异常,其主体异常对应于矿田。矿区大比例尺的岩石地球化学测量显示,这些指示元素的清晰的原生异常相互交替叠置于矿床内矿化富集部位,水平分带不甚明显,而垂直分带清晰。具有不同指示意义的元素组合于矿化的不同部位聚集而出现的分带,是用于评价矿化剥蚀程度及其成矿远景的重要地球化学参量  相似文献   
134.
PRO-GRADE: GIS toolkits for ground water recharge and discharge estimation   总被引:2,自引:0,他引:2  
Lin YF  Wang J  Valocchi AJ 《Ground water》2009,47(1):122-128
PRO-GRADE is an ESRI ArcGIS 9.2 plug-in package that consists of two separate toolkits: (1) the p attern r ecognition o rganizer for g eographic i nformation s ystem (PRO-GIS) and (2) the g round water r echarge a nd d ischarge e stimator for GIS (GRADE-GIS). PRO-GIS is a collection of several existing image-processing algorithms into one user interface to offer the flexibility to extract spatial patterns according to the user's needs. GRADE-GIS is a ground water recharge and discharge estimation interface using a mass balance method that requires only hydraulic conductivity, water table, and bedrock elevation data for simulating two-dimensional steady-state unconfined aquifers. PRO-GRADE was developed to assist ongoing assessments of the water resources in Illinois and Wisconsin, and is being used to assist several ground water resource studies in several locations in the United States. The advantage of using PRO-GRADE is to enable fast production of initial recharge and discharge maps that can be further enhanced by using a follow-up ground water flow model with parameter estimation codes. PRO-GRADE leverages ArcGIS to provide a computer-assisted framework to support expert judgment in order to efficiently select alternative recharge and discharge maps that can be used as (1) guidelines for field study planning and decision making; (2) initial conditions for numerical simulation; and (3) screening for alternative model selection and prediction/parameter uncertainty evaluation. In addition, PRO-GRADE allows for more easy and rapid correlation of those maps with other hydrologically relevant geospatial data.  相似文献   
135.
龙王尖金矿地球化学异常特征及找矿标志   总被引:1,自引:0,他引:1  
在广泛地研究了与金矿有关的组份分布的基础上,确定了该矿床赋有高含量的Au、Ag、As、Sb、Hg、Pb、Zn、Co、Ni和低含量的Cu、Mo、Ba、Bi、B、Mn,讨论了这些指示元素在土壤和岩石地球化学异常中的特征,初步建立了该金矿的地球化学找矿标志,确认该矿床为断裂破碎蚀变岩型金矿。  相似文献   
136.
针对平原区多目标地球化学调查工作中亟待解决的技术问题,在试验研究资料基础上,本文提出了平原区多目标地球化学调查异常查证及生态效应评价方法。异常查证阶段,首先应用相关关系法确定异常组分的地球化学基准值,而后进行异常分类,确定异常的成因和形成机理,为异常生态效应评价提供理论基础。在异常生态效应评价中,首先要弄清土壤中异常组分全量与其活性组分间的关系,进而探讨土壤和农作物中异常组分的含量关系,最终依据相关标准,评估农作物中重金属元素的含量水平,及其通过食物链对人体健康可能造成的危害。  相似文献   
137.
中国花岗岩类化学元素丰度及特征   总被引:21,自引:0,他引:21  
在全国范围内 750个有代表性的大中花岗岩类岩体上,采集了 6 080件样品,组合成 768件组合样.所有样品完全采用无污染加工方案进行加工和制备.选用了以电感耦合等离子体质谱 (ICP-MS)、仪器中子活化和 X射线荧光光谱为主的多种先进的分析方法对这些花岗岩类样品进行了分析测试,实测元素近 70种.使用国家一级地球化学标准物质和重复测试样品进行质量监控,确保了分析数据的准确性和可靠性.依据这些实测分析数据,计算并提出了中国花岗岩类和不同构造单元、不同时代花岗岩类的近 70种化学元素或成分的丰度,探讨了中国花岗岩类和不同构造单元、不同时代花岗岩类元素丰度的特征.  相似文献   
138.
The transition zone comprises Campbellrand microbialaminated (replacing "cryptalgalaminate") limestone and shale, with minor dolomite, conformably overlain by the Kuruman Iron Formation of which the basal part is characterized by siderite-rich microbanded iron-formation with minor magnetite and some hematite-containing units. The iron-formation contains subordinate intraclastic and microbialaminated siderite mesobands and was deposited in deeper water than the limestones. The sequence is virtually unaltered with diagenetic mineral assemblages reflecting a temperature interval of about 110 degrees to 170 degrees C and pressures of 2 kbars. Carbonate minerals in the different rock types are represented by primary micritic precipitates (now recrystallized to microsparite), early precompactional sparry cements and concretions, deep burial limpid euhedral sparites, and spar cements precipitated from metamorphic fluids in close contact with diabase sills. Paragenetic pathways of the carbonate minerals are broadly similar in all lithofacies with kerogen intimately associated with them. Kerogen occurs as pigmentation in carbonate crystals, as reworked organic detritus in clastic-textured carbonate units, and as segregations of kerogen pigment around late diagenetic carbonate crystals. Locally kerogen may also be replaced by carbonate spar. Carbon isotope compositions of the carbonate minerals and kerogen are dependent on their mode of occurrence and on the composition of the dominant carbonate species in a specific lithofacies. Integration of sedimentary, petrographic, geochemical, and isotopic results makes it possible to distinguish between depositional, early diagenetic, deep burial, and metamorphic effects on the isotopic compositions of the carbonate minerals and the kerogen in the sequence. Major conclusions are that deep burial thermal decarboxylation led to 13C depletion in euhedral ferroan sparites and 13C enrichment in kerogen (organic carbon). Metamorphic sparites are most depleted in 13C. Carbonates in oxide-rich iron-formations are more depleted in 13C than those in siderite-rich iron-formation whereas the kerogens in oxide banded iron-formations (BIF) are more enriched. This implies that the siderite-rich iron-formations were not derived from oxide-rich iron-formation through reduction of ferric iron by organic matter. Organic matter oxidation by ferric iron did, however, decrease the abundance of kerogen in oxide-rich iron-formation and led to the formation of isotopically very light sparry carbonates. Siderite and calcmicrosparite both represent recrystallized primary micritic precipitates but differ in their 13C composition, with the siderites depleted in 13C by 4.6 per mil on average relative to calcmicrosparite. This means that the siderites were precipitated from water with dissolved inorganic carbon depleted in 13C by about 9 per mil relative to that from which the limestones precipitated. This implies an ocean system stratified with regard to total carbonate, with the deeper water, from which siderite-rich iron-formation formed, depleted in 13C. Iron-formations were deposited in areas of very low organic matter supply. Depletion of 13C may, therefore, derive not from degradation of organic matter but from hydrothermal activity, a conclusion which is supported by 18O composition of the carbonate minerals and trace element and rare earth element (REE) compositions of the iron-formations.  相似文献   
139.
依据城山多金属矿化区地质特征,结合已知矿元素的空间分布规律,研究了矿区地球化学成矿环境,矿化地球化学判别指标,对区内新发现的异常进行了地球化学成矿环境分析和异常识别,提出了区内有寻找热液型多金属的找矿靶区.  相似文献   
140.
Caged dogwhelks (Nucella lapillus) and mussels (Mytilus edulis) were placed in situ at sites along the River Tyne (UK) in order to investigate the potential for monitoring any change in tributyltin (TBT) mediated effects. After 6 months the development of imposex was investigated in the dogwhelks and concentrations of TBT were determined in the whole tissues of both species. Sites within the estuary showed a high degree of imposex, whilst those at sites North and South of the estuary mouth exhibited significantly lower induction. Concentrations of TBT measured in the dogwhelk and mussel tissues showed the same pattern. The success of the caging technique, occurrence of imposex at other UK sites and the need for further monitoring at TBT impacted locations in the light of current international controls on the use of TBT-based antifouling paints on sea-going vessels are discussed.  相似文献   
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