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113.
Heritiana Rakoto Pierre Andrieux Jean-Bruno Ratsimbazafy Vittorio Iliceto Eddy Rasolomanana Louis Pastor Gian Maria Zuppi 《Comptes Rendus Geoscience》2003,335(4):355-363
A gravimetric survey has been carried out in a sedimentary basin, south of Madagascar, in order to define the bedrock morphology. The bedrock is made up of crystalline and volcanic rocks. The objective of the survey was to demonstrate whether a relationship could be established between bedrock morphology and groundwater mineralisation. Indeed, bedrock morphology has been successfully mapped and it is confirmed that most of the low mineralisation wells are located in areas where the slope of the bedrock is trending to the south-west, which ensures a higher hydraulic conductivity, i.e. a faster water flow, than in the other parts of the survey area. To cite this article: H. Rakoto et al., C. R. Geoscience 335 (2003). 相似文献
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The paper presents an attempt to determine the characteristics of karst aquifers using information on groundwater level (GWL) in natural holes and boreholes with different data quantity and time resolution of GWL measurements. In this paper the particulars of karst aquifers were analysed for four examples from the Dinaric karst. In all four study areas, aquifers are formed in bare, deep and well‐developed Dinaric karst consisting of Cretaceous limestones. The first example represents a wide area of Imotsko polje in the karst. The aquifer was analysed on the basis of infrequent water level monitoring in natural karst water features (jamas, lakes, wells) and discharges of springs and rivers. The karst aquifer in this example is complex, non‐homogenous and variable in space and time, which is frequent in the Dinaric karst. Regardless of the aforementioned it was possible to determine its elementary characteristics. The second example represents 10 wells used for the water supply for the city of Pula. The GWL and salinity were measured once a week in the period between 1981 and 1996. Even though these measurements were relatively infrequent in space and time, they served as bases for assessment of average and maximum aquifer conditions as well as boundaries of saltwater intrusion. In the third example only a portion of aquifer of the karst spring Blaz, which is in the contact with the Adriatic Seas, has been analyzed. It is a spring with an intrusion of salt water. For purposes of study of saltwater intrusion, 26 piezometers were drilled in its vicinity in which GWL, salinity and temperature were measured once a day during 168 days, a period comprising one complete cycle of seawater intrusion and retreat. These measurements proved the existence of dispersed discharge from the aquifer into the sea and its non‐homogeneity in space. In the fourth example GWL was measured continuously in 10 deep (up to 300 m) piezometers in the hinterland of the Ombla Spring catchment. The measurement period lasted 2 years (January 1988 to December 1989). The analyses are made with hourly data. The results made it possible to determine numerous characteristics of the karst aquifer and a significant non‐homogeneity of groundwater distribution in karst aquifers, depending more on the underground karst phenomena than the surface karst forms. Copyright © 2000 John Wiley & Sons, Ltd. 相似文献
116.
洪范池铁矿体赋存于太古宙泰山岩群山草峪组,矿体周围泉水众多,论证矿床开采疏排水能否对泉水产生影响具有重要意义。研究分析表明,朱砂洞组含水层及山草峪组风氧化带裂隙水是矿床充水的直接充水水源,矿床充水水文地质条件属简单类型。泉水出露于寒武纪张夏组含水层中,并且与山草峪组含水层间无水力联系。若张夏组含水层不与采区沟通,矿山生产疏排水不会对泉水产生明显的影响。 相似文献
117.
北京延庆地区地热开发对水文地质条件的影响 总被引:2,自引:0,他引:2
本文结合延庆盆地地热地质条件,从地热尾水的回灌、地面沉降原因、地震发生的机理等方面,全面、客观地分析了地热开发不会造成地表环境污染,也不会诱发地面沉降、地震等一系列的地质灾害问题,解除了人们对地热开发的顾虑,坚定了延庆地区利用地热供暖替代燃煤供暖的决心,为建立延庆生态模范县寻找到一种可利用的新能源。 相似文献
118.
Akköprü Dam, which is under construction, is located at Dalaman Basin in the southwest of Turkey. The base rock at the Akköprü dam site and reservoir area is autochthon Akta? limestone and Gökseki flysch formation. Allochthon Cehennem Deresi limestone, a complex series of ferro- (melange) and peridotite–serpentine units, overlay this unit with tectonic contact. These units are covered by young sedimentary series. The outcrops of karstified Akta? limestone are observed at 2 km upstream of the dam site, at the right reservoir abutment. This unit is very permeable and the groundwater level is very deep, 100–116 m below the Dalaman riverbed. After impoundment, 250,000 m2 of this unit will be submerged. Groundwater which percolates in this unit discharges at the coastal springs. This study analyzed the watertightness of Akköprü reservoir related to the karstified limestone in the left reservoir bank and discussed possible options of remedial works to reduce seepage. 相似文献
119.
Darren A. Bennetts John A. Webb Malcolm McCaskill Reto Zollinger 《Hydrogeology Journal》2007,15(6):1197-1210
Detailed study of a localised saline discharge zone in southeastern Australia shows that the salinisation is mostly due to
the shallow water table (<1–2 m from the surface). Direct evaporation, particularly in summer, leads to extremely high soil–water
salinities at the surface, even though the underlying groundwater is moderately fresh. Groundwater discharge is localised
at a break of slope, where the water table intersects the surface, and where the transition from permeable sands to clay-rich
sediments inhibits lateral groundwater flow. Higher salt concentrations build up in the clays because of the long residence
times during which soil-waters are exposed to evapotranspiration and the reduced potential for salts to be flushed from the
sediments. As a result the saline discharge area does not correspond to the part of the site with the largest salt store.
Results of the study demonstrate that for dryland salinisation to occur, the groundwater beneath the discharge zone need not
be saline, and the presence of a large salt store does not necessarily lead to problems of dryland salinisation if, as in
the clay-rich sediments at the site, the salt lies below the pasture root zone. Furthermore, mobilisation of salt stores within
low permeability sediments by rising groundwater may be minor.
Résumé L’étude détaillée d’une zone localisée d’émergence salée au sud-est de l’Australie montre que la salinisation est surtout due à la nappe phréatique (<1–2 m sous la surface). L’évaporation directe, particulièrement durant l’été, conduit à des salinités de l’eau du sol extrêmement élevées à la surface, même si l’eau souterraine sous-jacente est modérément douce. L’émergence de l’eau souterraine est localisée à la rupture de pente, là où la nappe phréatique rencontre la surface du sol et où la transition entre sables perméables et sédiments riches en argiles inhibe les écoulements d’eau souterraine latéraux. Les plus fortes concentrations en sel s’accumulent dans les argiles du fait de temps de résidence élevés, durant lesquels les eaux du sol sont exposées à l’évapotranspiration et à un lessivage réduit des sédiments. Il en résulte que l’aire d’émergence des eaux salées ne correspond pas à la partie du site rencontrant la réserve de sel la plus importante. Les résultats de l’étude démontrent que pour que la salinisation d’une zone aride devienne effective, l’eau souterraine sous la zone ne doit pas être forcément salée, et la présence d’une zone étendue de réserve de sel ne conduit pas forcément à des problèmes de salinisation de zones arides si, comme dans les sédiments argileux du site, le sel ne repose pas sous la zone de pature. De plus, la mobilisation des réserves de sel dans les sédiments peu perméables par la montée du niveau de l’eau souterraine devrait être mineure.
Resumen El estudio detallado de una zona local de descarga salina en el sudeste de Australia, muestra que la salinización es principalmente debido a un nivel freático poco profundo (<1–2 m de la superficie). La evaporación Directa, particularmente en verano, conlleva a salinidades de suelo-agua sumamente altas en la superficie, aunque el agua subterránea subyacente es moderadamente dulce. La descarga de Agua subterránea se localiza en una interrupción de la ladera, dónde el nivel freático intercepta la superficie, y donde la transición de las arenas permeables a los sedimentos ricos en arcilla inhibe el flujo lateral del agua subterránea. Las concentraciones de sal más altas se forman en las arcillas debido a los tiempos de residencia largos durante los cuales se exponen el conjunto suelo-agua a la evapotranspiración y también por el potencial reducido para las sales de ser expulsadas de los sedimentos. Como resultado el área de la descarga salina no corresponde a la parte del sitio con el contenido de sal más grande. Los resultados del estudio demuestran que para que ocurra la salinización en terrenos secos, el agua subterránea bajo la de zona de descarga no necesita ser salina, y que la presencia de un almacenamiento de sal grande, no necesariamente lleva a los problemas de salinización en terrenos secos si, como en los sedimentos ricos en arcilla del sitio, la sal yace debajo de la zona de raíz de la pastura. Además, la movilidad de depósitos de sal dentro de los sedimentos de permeabilidad baja pueden ser menores, por causa del agua subterránea ascendente.相似文献
120.
综合物探在山东某矿井采区的应用 总被引:2,自引:0,他引:2
山东某勘探区内目的层为3#煤层,厚度1.65-3m,与围岩物性差异明显,能形成校强反射波,根据其地震数据波组特征、频谱特征等相关信息解释了3#煤层赋在状态风氧化带范围及断层分布规律等,并根据瞬变电磁资料,圈定了3#煤层顶扳砂岩富水带。 相似文献