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991.
TWO TYPES OF CENOZOIC HIGH-K MAGMATINSM IN EASTERN TIBET:IMPLICATIONS FOR THE NATURE OF MANTLE SOURCES1 ArnaudNO ,VidalP ,TapponnierP ,etal.ThehighK2 OvolcanismofnorthwesternTibet:geochemistryandtectonicim plications[J] :EarthPlanetSciLett,1991,11:351~ 36 7.
2 DengW .CenozoicvolcanicrocksinthenorthernNgaridistrictoftheTibet Discussionontheconcurrentsubduction[J] .Ac taPetrolSinica ,1989( 3) :1~ 11.
3 HarrisonTM ,LeloupPH ,RyersonFJ,… 相似文献
992.
993.
报道了大柴旦盐湖DC1303沉积剖面硼矿层及其下伏沉积地层的矿物学、有机质烧失量(LOI)等环境指标的研究结果,首次探讨硼矿层下伏灰黄色粉砂质粘土层沉积以来大柴旦湖水水化学演变及其与区域气候变化的关联。根据剖面的岩性、矿物组合和有机质烧失量(LOI)将研究剖面划分为3个沉积单元:I.灰黄色粉砂质粘土层(623~423cm)、II.灰黑色淤泥夹结核层(423—407cm)、III.柱硼铁石矿层(407—395em)。研究结果表明,在湖底硼矿层形成之前的较长时期内,大柴旦湖是碎屑沉积为主的非盐湖相沉积环境,直到单元I顶层20cm沉积物中才开始出现少量石膏。此后快速进入硫酸盐型盐湖沉积阶段(II)和湖底柱硼镁石矿层形成阶段(Ⅲ)。有机烧失量在I1、I2和I3单元中呈阶段性增加预示区域气温稳步上升,由此导致山区降水量增加和湖区蒸发量增强。湖泊环境变化是区域水文气候条件改变的结果。 相似文献
994.
995.
996.
从中国盐湖钾盐 5 0年回顾 ,充分阐述了中国盐湖资源多、大、富、全等特点 ,及科学家们取得的科技成果。针对中国盐湖钾盐综合利用和高值化开发 ,提出了几点建议。 相似文献
997.
介绍了盐湖和盐田卤水动态自动观测系统的发展概况 ;论述了系统的结构及其硬件和软件工作原理 ;作为主要关键技术 ,介绍了盐湖野外单片机数据采集系统和测量仪器的设计方法 ,卤水水位、温度、密度传感器的研制以及高浓度卤水中钾的直接自动监测方法。卤水动态自动观测系统在察尔汗盐湖和青海钾肥一期工程盐田中取得了很好的应用效果。这项技术有广泛的推广应用前景 相似文献
998.
Seismicity of the Sea of Marmara (Turkey) since 1500 总被引:5,自引:0,他引:5
999.
Superposed deformation straddling the continental-oceanic transition in deep-water Angola 总被引:3,自引:0,他引:3
The Angolan margin is the type area for raft tectonics. New seismic data reveal the contractional buffer for this thin-skinned extension. A 200-km-long composite section from the Lower Congo Basin and Kwanza Basin illustrates a complex history of superposed deformation caused by: (1) progradation of the margin; and (2) episodic Tertiary epeirogenic uplift. Late Cretaceous tectonics was driven by a gentle slope created by thermal subsidence; extensional rafting took place updip, contractional thrusting and buckling downdip; some distal folds were possibly unroofed to form massive salt walls. Oligocene deformation was triggered by gentle kinking of the Atlantic Hinge Zone as the shelf and coastal plain rose by 2 or 3 km; relative uplift stripped Paleogene cover off the shelf, provided space for Miocene progradation, and steepened the continental slope, triggering more extension and buckling. In the Neogene, a subsalt half graben was inverted or reactivated, creating keystone faults that may have controlled the Congo Canyon; a thrust duplex of seaward-displaced salt jacked up the former abyssal plain, creating a plateau of salt 3–4 km thick on the present lower slope. The Angola Escarpment may be the toe of the Angola thrust nappe, in which a largely Cretaceous roof of gently buckled strata, was transported seawards above the thickened salt by up to 20 km. 相似文献
1000.
J. B. Dirkzwager J. D. Van Wees S. A. P. L. Cloetingh M. C. Geluk B. Dost F. Beekman 《Global and Planetary Change》2000,27(1-4)
The pattern of fault reactivation, basin deformation and concentration of seismicity along the main trans-Netherlands fault zone, located NW–SE across the centre of the Netherlands, indicates that this zone is a major zone of weakness. Gravity modelling reveals after back-stripping of the sedimentary succession a distinctive continuous positive anomaly that can be explained by lithospheric sources. This zone of weakness is therefore likely to have a major influence on the tectonic processes currently active in the Netherlands region. We give a review of the tectonic history of the Netherlands and then present the results of a quantitative study of the reactivation of basin boundary faults and the influence on the surrounding basin. Well-data, balanced and back-stripped cross-sections are used to constrain the lithosphere rheology. The lithosphere rheology modelling results show a weak coupling between upper crustal deformation and the subcrustal lithosphere. A finite element modelling approach focussing on the upper crust is carried out in which the basin boundary faults are assigned various dips. The modelling results indicate that, for continuous reactivation of basin boundary faults, the presence of both a pre-existing weakness and a reduced friction angle is required. The latter implies that large displacements accommodated by primary faults cannot be directly attributed to the relative weakness of these faults compared to the secondary faults, which is in close accordance with inferences from trenching. A reduced friction angle has a significant effect on lithospheric strength and appears to be the major controlling factor in the reactivation of basin boundary faults. 相似文献