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311.
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特低渗透砂岩储层可动流体变化特征与差异性成因——以鄂尔多斯盆地延长组为例 总被引:1,自引:0,他引:1
特低渗透砂岩储层微观孔隙结构复杂,流体赋存状态不同于常规储层,利用核磁共振技术对鄂尔多斯盆地延长组3个层位样品的可动流体变化特征与差异性成因进行了分析。结果表明,样品T2谱分布主要表现出4种形态、T2截止值中等—偏高、可动流体参数变化幅度较大;沉积和成岩作用差异导致微观特征参数不同,造成各层位可动流体参数复杂变化;渗透率较小时,可动流体参数变化幅度大,当渗透率增大到一定程度后,可动流体参数数据点收敛,变化幅度减小;储层物性、孔隙(尤其是次生孔隙)发育连通程度、微裂缝的发育程度、粘土矿物的存在形式及其对孔隙的充填程度等微观孔隙结构特征变化是可动流体参数差异性产生的主要原因。可动流体参数本身就是储层诸多微观特征参数的综合反映,应在储层评价中予以考虑。 相似文献
313.
Fluvial ribbon sandstone bodies are ubiquitous in the Ebro Basin in North‐eastern Spain; their internal organization and the mechanics of deposition are as yet insufficiently known. A quarrying operation in an Oligocene fluvial ribbon sandstone body in the southern Ebro Basin allowed for a three‐dimensional reconstruction of the sedimentary architecture of the deposit. The sandstone is largely a medium‐grained to coarse‐grained, moderately sorted lithic arenite. In cross‐section, the sandstone body is 7 m thick, occupies a 5 m deep incision and wedges out laterally, forming a ‘wing’ that intercalates with horizontal floodplain deposits in the overbank region. Three architectural units were distinguished. The lowest and highest units (Units A and C) mostly consist of medium‐grained to coarse‐grained sandstone with medium‐scale trough cross‐bedding and large‐scale inclined stratasets. Each of Units A and C comprises a fining‐up stratal sequence reflecting deposition during one flood event. The middle unit (Unit B) consists of thinly bedded, fine‐grained sandstone/mudstone couplets and represents a time period when the channel was occupied by low‐discharge flows. The adjoining ‘wing’ consists of fine‐grained sandstone beds, with mudstone interlayers, correlative to strata in Units A and C in the main body of the ribbon sandstone. In plan view, the ribbon sandstone comprises an upstream bend and a downstream straight reach. In the upstream bend, large‐scale inclined stratasets up to 3 m in thickness represent four bank‐attached lateral channel bars, two in each of Units A and C. The lateral bars migrated downflow and did not develop into point bars. In the straight downstream reach, a tabular cross‐set in Unit A represents a mid‐channel transverse bar. In Unit C, a very coarse‐grained, unstratified interval is interpreted as deposited in a riffle zone, and gives way downstream to a large mid‐channel bar. The relatively simple architecture of these bars suggests that they developed as unit bars. Channel margin‐derived slump blocks cover the upper bar. The youngest deposit is fine‐grained sandstone and mudstone that accumulated immediately before avulsion and channel abandonment. Deposition of the studied sandstone body reflects transport‐limited sediment discharges, possibly attaining transient hyperconcentrated conditions. 相似文献
314.
在以往实验的基础上,充分考虑岩石在温度作用下内部结构变化,选用阜新地层砂岩进行高温下的渗透率的实验研究。实验结果得砂岩的渗透率随温度增加而降低,为研究阜新地层地热开发提供理论基础。 相似文献
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川东南-湘西地区志留系小河坝组砂岩微量元素地球化学特征及意义 总被引:2,自引:0,他引:2
砂岩岩石地球化学对沉积盆地形成时期构造背景的稳定与否有着较高的敏感度,已成为地质构造复杂地区研究的有效手段。采用电感耦合等离子体质谱(ICP-MS)测定了川东南-湘西地区志留系小河坝组37件砂岩样品的微量元素质量分数,应用w(V)/w(Ni)、w(V)/w(V+Ni)、w(Sr)/w(Ba)及w(V)/w(Sc)等特征微量元素比值及w(Zr)-w(Th)、w(La)-w(Sc)-w(Th)和w(Th)-w(Sc)-w(Zr)/10等多种沉积构造背景判别图解和多种参数交叉分析对研究区志留纪小河坝期砂岩的沉积环境及其源区构造背景进行了研究,结果表明:该区志留纪小河坝期总体上为缺氧的滞流浅海沉积环境,而靠近雪峰山隆起龙山县地区为贫氧环境。其源区沉积构造背景具有活动大陆边缘、大陆岛弧和被动大陆边缘的性质。 相似文献
317.
318.
鄂尔多斯盆地东部山西组山_2~3亚段砂岩判别图版、砂岩分布规律及成因探讨 总被引:1,自引:1,他引:0
勘探实践表明鄂尔多斯盆地东部山西组山32亚段含气性与岩性存在直接关系,石英砂岩储层往往是高产层。因此,寻找石英砂岩储层是该区勘探开发的重点。在岩心刻度测井的基础上,利用测井参数建立了3种类型砂岩的测井判别蛛网图版,并回归了石英相对百分含量与测井参数之间的关系式,利用此关系式对山32亚段砂岩类型进行识别,判识准确率达到80%。同时结合岩石薄片鉴定等资料,绘制了研究区砂岩类型平面分布图。单井结合平面图分析发现研究区存在3个环带状石英砂岩分布区域。从大地构造环境、物源、沉积环境等方面对该区山32亚段石英含量普遍较高和平面环带状分布原因进行了探讨,认为受海退影响的海岸线频繁变迁是形成石英砂岩分布的主要因素。 相似文献
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320.
Moshood Niyi Tijani Matthew Essien Nton Ryuji Kitagawa 《Comptes Rendus Geoscience》2010,342(2):136-150
This study presents the mineralogical, textural and geochemical characteristics of the regional Maastrichtian Ajali Sandstone in Anambra Basin, SE Nigeria. The intent is to highlight possible constraints on the chemical weathering conditions of the source materials on one hand, and to infer the provenance on the other hand. The investigation approach involved field studies and collection of samples from 12 different outcrop locations, followed by laboratory studies involving grain-size analysis (GSA), major and trace elements analyses using the X-ray fluorescence (XRF) method as well as thin section petrography. Field studies show that the sandstones are friable at all locations and range in color from white in freshly cut stone, to reddish brown on weathering. In addition, the sandstone units are cross-bedded and show graded bedding exemplified by fining upward sequence. Textural examination indicates that the sandstones range from fine to medium sands, constituting about 76 to 99% sand fraction, with graphic mean grain size of 0.23 to 0.53 mm. Standard deviation (sorting) ranges from 0.56 to 1.24 Ø and implies moderately well sorted sediments. Inferred from the textural indices, the depo-environmental discrimination of the Ajali Sandstone revealed a fluvial/river system-dominated sedimentary process. The sandstones are quartz arenite with quartz greater than 90% and less than 5% K-feldspar which indicate a predominant basement source as also revealed by the heavy mineral assemblages. In addition, major elemental oxides shows SiO2 content greater than 96% for the fresh Ajali Sandstone samples with extreme depletion of mobile oxides such as Na2O, CaO and the ferromagnesian minerals through weathering and sedimentary processes. Provenance and tectonic setting discrimination using geochemical data and compositional maturity revealed typical felsic igneous-dominated cratonic environment while inter-elemental ratios (such as Zr/Cr, Y/Ni, Th/Sc, La/Sc and La/Co) and ternary plots (e.g. Th–Sc–Zr; La-Th–Sc and Th-Co-Zr) reflect passive continental margin setting for the Ajali Sandstone. Consequently, the source area is constrained to the Precambrian basement rock units of Adamawa-Oban massif areas to the east of the Anambra Basin and the adjacent Abakaliki Anticlinorium. 相似文献