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581.
开展“中国天然氧吧”品牌效益评估,对推动生态产品价值转换具有重要意义。运用层次分析法从生态效益、经济效益、社会效益三个方面构建了“中国天然氧吧”品牌效益评估指标体系,并细化为23个具体指标。结合模糊综合评价法,以江西省乐安县为例进行实际应用检验。结果表明:1)此效益评估体系和评估方法具有科学性和合理性,评价结果可以为政府部门合理开发旅游气候资源、推动“中国天然氧吧”品牌可持续发展提供借鉴。2)乐安县“中国天然氧吧”品牌综合效益属“良好”等级。3)针对低评分指标,提出当地政府需要加强生态环境保护规划、生态旅游开发力度和品牌宣传推广等建议。  相似文献   
582.
四川省白玉县呷村银多金属矿床是中国著名的VHMS矿床之一,前人曾进行过详细的矿床模型研究。对于矿床下部脉状矿体大致呈层状平行于上部块状矿体的地质现象,前人曾提出"层状矿席+层控网脉状矿带"等模式。文章通过对呷村矿床地质特征的详细研究后认为,呷村矿床在印支期形成之后,遭受到燕山期弧-陆碰撞造山的强烈改造,导致矿区地层直立并倒转,并在能干性弱的流纹质火山岩中普遍发生层内韧性剪切变形,使原先近于垂直层状矿体和喷气沉积岩的下-中部脉状-网脉状矿体被构造置换为紧闭褶皱状、无根褶皱状、透镜体状,并近于平行于上部层状矿体。构造恢复表明,下-中部脉状-网脉状矿体原始三维形态为不整合的筒状或漏斗状,与上部层状矿体组成典型的"下筒上层"的"双层结构"。根据脉状-网脉状矿体和层状矿体的空间展布特征,在构造恢复的基础上重新建立了呷村VHMS矿床的双通道夹卤水池的矿床模型。该模型对矿区外围找矿有一定的指导意义。  相似文献   
583.
Sonic velocities in the Toolonga Calcilutite (Upper Cretaceous), the Gearle Siltstone and Haycock Marl (mid‐Cretaceous), and the Muderong Shale (Lower Cretaceous) were each used to independently quantify apparent uplift (height above maximum burial depth) in the Carnarvon Basin. Apparent uplift is given by the difference in depth between the present‐day velocity‐depth trend for a unit in a particular well and the reference trend (unaffected by uplift) of the unit. Apparent uplift results derived from the Toolonga Calcilutite, Gearle Siltstone and Muderong Shale are statistically similar. The consistency of results from carbonate and clastic units suggests that, at the formation and regional scale, overcompaction (i.e. anomalously high interval velocity) in these three units reflects previously greater burial depth, rather than sedimentological and/or diagenetic processes, and validates the use of lithologies other than shale in maximum burial‐depth studies. The proposed magnitudes of apparent uplift are greatest along some of the main structural highs of the Carnarvon Basin. Apparent uplift of approximately 800 m was determined along the Legendre Trend, and along the Barrow Arch. In excess of 900 m of apparent uplift was determined on the Bambra Anticline. The consistency of results from units of Early to Late Cretaceous age suggests that uplift must have post‐dated the youngest (Late Cretaceous) unit analysed.  相似文献   
584.
New insights into the 3D structure, composition and origin of the Mt Ashmore dome, west Bonaparte Basin, Timor Sea, are enabled by reprocessed seismic-reflection data and by optical microscopic, X-ray diffraction (XRD), scanning electron microscopy (SEM)/energy dispersive spectrometry (EDS) and transmission electron microscopy (TEM) analyses of drill cuttings. The structural dome, located below a major pre-Oligocene post-Late Eocene unconformity and above a ~6 km-deep-seated basement high indicated by marked gravity and magnetic anomalies, displays chaotic deformation at its core and a centripetal kinematic deformation pattern. A study of drill cuttings of Lower Oligocene to Lower Jurassic sedimentary rocks intersected by the Mt Ashmore 1B petroleum-exploration well reveals microbrecciation and extreme comminution and flow-textured fluidisation of altered sedimentary material. The microbreccia is dominated by aggregates of poorly diffracting micrometre to tens of micrometres-scale to sub-millimetre particles, including relic subplanar fractured quartz grains, carbonate, barite, apatite and K-feldspar. A similar assemblage occurs in fragments in basal Oligocene sediments, probably derived from the eroded top section of the dome, which protrudes above the unconformity. SEM coupled with EDS show the micrometre to tens of micrometres-scale particles are characterised by very low totals and non-stoichiometric compositions, including particles dominated by Si, Al–Si, Si–Ca–Al, Si–Al–Ca, Si–Mg, Fe–Mg–Ca, Fe–Mg and carbonate. XRD analysis identifies a high proportion of amorphous poorly diffracting material. TEM indicates internally heterogeneous, fragmented and recrystallised structure of the amorphous grains, which accounts for the low totals in terms of the high-volatile and porous nature of the particles. Another factor for the low totals is the uneven thin-section surfaces which affect the totals. No volcanic material or evaporites were encountered in the drillcore, militating against interpretations of the structure in terms of magmatic intrusion or salt diapirism. Such models are also inconsistent with the strong gravity and magnetic anomalies, which signify a basement high below the dome. An interpretation of the dome in terms of a central rebound uplift of an impact structure can not be proven due to the lack of shock metamorphic effects such as planar deformation features, impact melt or coesite. However, an impact model is consistent with the chaotic structure of the domal core, centripetal sense of deformation, microbrecciation, comminution and fluidisation of the Triassic to Eocene rocks. In this respect, an analogy can be drawn between the Mt Ashmore structural dome and likely but unproven impact structures formed in volatile (H2O, CO2)-rich sediments where shock is attenuated by high volatile pressure, such as Upheaval Dome, Utah. In terms of an impact hypothesis the Mt Ashmore dome is contemporaneous with a Late Eocene impact cluster (Popigai: D = 100 km, 35.7 ± 0.2 Ma; Chesapeake Bay: D = 85 km, 35.3 ± 0.1 Ma).  相似文献   
585.
鲁西地区作为华北克拉通的一部分,自古元古代早期(约2400Ma)二长花岗质岩石侵位以后至晚古生代(约250Ma),一直处于板内稳定地块状态,在这漫长的2150Ma年里仅形成了两期脉岩,即四堡期侵位的基性辉绿岩(牛岚单元)与中晚奥陶世侵位的超基性金伯利岩(常马庄单元)。经对控制辉绿岩侵位的构造特征进行研究发现,该构造体系不仅控制了鲁西辉绿岩的侵位,还控制了金伯利岩的侵位。在此基础上,对蒙阴金伯利岩带的控制规律进行了分析,并对金伯利岩带向南延伸的区域进行了初步的预测。  相似文献   
586.
煤的孔隙结构和比表面积不仅影响煤层气吸附与储集能力,而且对气体渗流和扩散有重要的控制作用。通过对芦岭煤矿8,9煤层煤样低温液氮实验,对比分析了原生结构煤和不同变形强度构造煤的孔隙结构与比表面积的变化。结果表明,构造煤的比表面积和总孔体积平均值是原生结构煤的2.95倍和3.84倍。随着煤体韧性变形强度增加,构造煤的比表面积逐渐增大,微孔占比增加,小孔和中孔占比较少,总孔体积变化以糜棱煤为界呈现先增加后减小的特点。  相似文献   
587.
Abstract

This work deals with the Cretaceous-Tertiary Helminthoid flysch successions of the Emilian Apennines and related basal complexes (Mt. Caio, Val Baganza, Solignano, Mt. Venere-Monghidoro and Mt. Cassio Units): it is based on an integrated approach which included stratigraphic, petrographic and structural observations. Detailed stratigraphic sections measured in the various successions evidenced the specific features of the different flysch formations. The main framework composition analysis of the arenites pointed out a partly ‘oceanic’ alimentation for the Mt. Caio Flysch Fm; the Mt. Venere-Monghidoro, and Mt. Cassio Flysch Fms have been alimented exclusively by a terrigenous detritus mainly derived from continental basement source areas. The heavy mineral assemblage of the Mt. Caio Flysch Fm is characterized by picotite, that of the Mt. Venere-Monghidoro, Solignano and Mt. Cassio Flysch Fms commonly contains straurolite, garnet and chloritoid, generally considered to be typical products of the Adriatic continental margin. The calcareous nannofossils biostratigraphy indicated that the flysch sedimentation started during the Late Campanian and ended between the Paleocene (Mt. Cassio Flysch Fm and Mt. Venere-Monghidoro Fms) and the Middle Eocene (Mt. Caio Flysch Fm). We propose a schematic paleogeographic restoration for the External Ligurian Domain which implies a more internal position for the Mt. Caio succession and a more external one for the Mt. Venere-Monghidoro and Mt. Cassio successions. The Helminthoid flyschs sedimented after and during deformation and subduction phases in perched and fore-arc basins partly overlying the marginal part of the Adriatic plate. The External Ligurian nappes’ stacking consists, in the study area, from the bottom, of the following units: Caio Unit, Val Baganza Ophiolitic Unit, Monghidoro Unit, Cassio Unit. This pile of thrust-nappes, sealed by the Epiligurian succession, has been already realized before Late Eocene. In our opinion it was generated by a frontal west-verging frontal accretion process (offscraping), which let the flysch successions remain, in this phase, quite undeformed. This westverging thrusting phase, starting from the Middle-Late Eocene, has been followed by an important folding event which generated striking hectometric and kilometric ‘Apenninic’ reverse folds, sometimes associated with NE-verging thrust surfaces. The Oligocene and post-Oligocene evolution is characterized by a block-translation of the Ligurian staking over the Subligurian, Tuscan and Umbrian Domains, associated with a new generation of minor thrusts and thrust related Apenninic folds. © 2000 Éditions scientifiques et médicales Elsevier SAS  相似文献   
588.
娄昊  木日根 《世界地质》2013,32(3):606-611
矿山开发给矿区环境带来了负面影响,对矿山环境质量进行评价是实现矿业可持续发展的必要手段。笔者建立了矿山岩土工程环境质量多目标评价指标体系,运用层次分析法确定出各个评价指标的权重; 规定了分级规则,并对各个评价指标进行了分级; 建立了矿山岩土工程体系环境质量多目标综合评价模型,并将该模型应用于矿山实际,得出该矿山环境质量较差,需及时采取措施进行治理。  相似文献   
589.
太行山东麓断裂带板内构造地貌反转与机制   总被引:5,自引:0,他引:5       下载免费PDF全文
华北克拉通前寒武纪基底可划分为东部地块、中部带和西部地块。中生代以来,华北克拉通发生减薄破坏,其破坏中心位于东部地块,而西部地块与中部带基本保持完整,其过渡带就是太行山东侧。太行山地区近乎平行发育着两条重要的断裂:太行山大断裂和太行山山前断裂,统称为太行山东麓断裂带。通过研究发现,太行山山前断裂是继承早前寒武纪构造带形成的断裂,控制着太行山与东部地块前寒武纪基底的差异,古新世以来发生板内构造地貌的负反转,构成渤海湾盆地的西界断裂。太行山大断裂则在燕山期时为重要的逆冲断裂,对太行山的隆起起着重要作用;中新世以来,伴随着山西地堑系的形成,太行山大断裂发生构造负反转,控制着一系列山间地堑的发育。新生代以来,该区构造演化特征整体表现为向西构造迁移的特点,是区域走滑伸展背景下的一种新的板内盆山关系。  相似文献   
590.
九龙山构造是川西北地区的重点勘探构造。据地震剖面分析,解析了九龙山的构造几何学特征。研究表明,九龙山背斜受到米仓山构造和龙门山构造的双重影响,主要经历了三期次构造叠加,其叠加组合形成了现今九龙山的复杂构造。通过合理的构造建模,对九龙山构造运动过程、多期构造叠加及油气运移与分布规律等有了新的认识。  相似文献   
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