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323.
EH4电导率连续成像系统在银厂坡地质勘查中的应用 总被引:1,自引:0,他引:1
通过EH4电磁方法在贵州威宁银厂坡地质勘查中的应用实例,并经过勘查、成矿靶位的确定、工程验证三个阶段工作后,认为EH4电磁方法在地质勘查中具有较好的应用效果。特别是在深部地球物理信息上优于其它常规物探方法,而它相对其它常规物探方法又更具有设备轻、速度快、费用低、精度较高等优点。 相似文献
324.
本文提出用于地下成像无源地震方法的分析,在该方法中应用环境地震噪声作为地下散射体的照明源。该成像算法能够以递归方式将新的数据融入到成像中,这使成像背景噪声随时间减少。在空间域不相干环境背景噪声的假设前提下推导出成像算法的点-扩展函数。点-扩展函数表征成像的分辨率,即接收排列长度和环境带宽的函数。 相似文献
325.
Integrated geophysical surveys using vertical electrical sounding (VES), very low frequency (VLF) EM, radiation counting,
total magnetic field and self-potential (SP) measurements are carried out to characterize the geothermal area around a hot
spring in the Nayagarh district, Orissa, India that lies in the East Indian geothermal province. The study was performed to
delineate the fracture pattern, contaminated groundwater movement and possible heating source. VES interpretations suggest
a three- to four-layer structure in the area. Resistivity survey near the hot spring suggests that weathered and fractured
formations constitute the main aquifer system and extend to 60 m depth. Current flow measured at various electrode separations
normalized by the applied voltage suggests that fractures extend to a greater depth. Detailed VLF study shows that fractures
extend beyond 70 m depth. VLF anomaly has also very good correlation with the total magnetic field measured along the same
profiles. Study results suggest that a gridded pattern of VLF survey could map the underground conductive fracture zones that
can identify the movement of contaminated groundwater flow. Therefore, precautionary measures can be taken to check further
contamination by delineating subsurface conducting structures. Self potential (SP) measured over the hot spring does not show
a large anomaly in favor of the presence of a sulphide mineral body. A small positive (5–15mV) SP anomaly is measured which
may be streaming potential due to subsurface fluid flow. A high radiation is measured about four kilometers from the hot spring,
suggesting possible radiogenic heating. However, the exact nature of the heating source and its depth is not known in the
area. Deep resistivity followed by a magneto-telluric survey could reveal the deeper structures. 相似文献
326.
Geoelectrical and hydrogeochemical studies for delineating seawater intrusion in the outlet of Wadi Ham, UAE 总被引:2,自引:0,他引:2
M. Sherif A. El Mahmoudi H. Garamoon A. Kacimov S. Akram A. Ebraheem A. Shetty 《Environmental Geology》2006,49(4):536-551
The Quaternary aquifer of Wadi Ham, UAE has been overexploited during the last two decades to meet the increasing water demands.
As a result, the dynamic balance between freshwater and seawater has been disturbed and the quality of the groundwater has
deteriorated. In this paper, a 2D earth resistivity survey was conducted in Wadi Ham in the area between Fujairah and Kalba
to delineate the seawater intrusion. Existing monitoring wells were used to measure the horizontal and vertical variations
in water salinity and thus to improve the interpretation of earth resistivity imaging data. Results of vertical electrical
soundings and chemical analyses of collected water samples were used to obtain an empirical relationship between the inferred
earth resistivity and the amount of total dissolved solids. This relationship was used along with the true resistivity sections
resulting from the inversion of 2D resistivity data to identify three zones of water-bearing formation (fresh, brackish, and
salt-water zones). Along the four 2D resistivity profiles, the depth to the fresh-brackish interface exceeded 50 m at the
western part of the area and was in the order of 10 m or less in the eastern side near the shoreline. Depth to the brackish-saline
water interface reached about 70 m in the western side and was in the order of 20 m in the eastern side. The thickness of
the fresh water zone decreases considerably in the farming areas toward Kalba and thus the degree of seawater intrusion increases. 相似文献
327.
Environmental data are highly variable. They also include uncertainties resulting from all steps of the analytical process e. g. sampling, or sampling pre‐treatment. However, a lot of information is unfortunately often lost because only univariate statistical methods are used for data evaluation and interpretation. This neglects correlation between different pollutants and relationships among various sampling points. It is therefore necessary to apply additional methods of analysis that can accommodate such relationships. This ability is provided by the established, and by the more modern, multivariate statistical methods because they can analyze complex sets of multidimensional data. These methods are used to visualize large amounts of data and to extract latent information (e. g. differently polluted areas, dischargers, or interactions between different environmental compartments). The goal of this paper is to present the use of established statistical techniques, like cluster or factor analysis, and the progress made in basic modern techniques (e. g. cluster imaging, multiway‐partial least squares regression, projection pursuit, or information theory) and to demonstrate each with examples and illustrations. 相似文献
328.
329.
天然地震层析成像相对于传统的反射地震方法而言是一种新的经济的勘探方法。这是由于天然地震层析成像所需的观测值直接来自于研究区下方发生的天然微地震,而反射地震却需要在研究区表面进行人工放炮。因此本工作是将天然地震层析成像方法应用于柴达木盆地西部某油田约100km2地区的深层构造的尝试性研究。626个地震事件的3289个P波到时的初步结果与研究区已知的大的构造吻合较好。该模型中非常显著的特征就是观测到一个北西向的背斜。此外,微地震的分布也与研究区中活动断裂带的位置基本一致。 相似文献
330.
用三维激光成像技术调查高陡边坡岩体结构 总被引:3,自引:0,他引:3
论文针对“罗盘 皮尺”传统模式调查高陡边坡岩体结构中的缺点,提出了三维激光成像技术调查高陡边坡岩体结构的新方法。利用三维激光成像技术可获得完全实景的数字模型,并在该数字模型上可直接量取点、线、面和三维实体空间坐标,从而进行结构面产状、迹长与连通率、间距等岩体结构特征参数计算和地质剖面切图。最后,以营盘山陡崖边坡为例,详细阐述了三维激光成像技术调查高陡边坡岩体结构特征参数方法及过程。结果表明,利用三维激光成像技术所得的结构面产状、间距等岩体结构特征参数要优于传统的“罗盘 皮尺”量测结果。因此,三维激光成像技术的引入,必将引发岩体结构特征参数测试技术革新性的发展。 相似文献