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61.
Hydrological characteristics of karstic groundwater in the northeast Viet Nam as studied by isotopic techniques 总被引:1,自引:0,他引:1
Dang Duc Nhan Nguyen Van Lam Ha Chu Ha Long Dao Dinh Thuan Dang Anh Minh Vo Thi Anh 《Environmental Earth Sciences》2013,70(2):521-529
The stable water isotopic composition (δ2H and δ18Ο), tritium (3H) activity, dissolved organic carbon, alkalinity, as well as the composition of carbon 13 (δ13C) in dissolved inorganic carbon (DIC) of 36 water samples taken from 16 resurgences in the northeast provinces of Viet Nam in the dry (Mar 2008) and rainy (June 2008) seasons were analyzed to elucidate hydrological characteristics of the karstic aquifers in the area. The stable water isotopic composition of the water samples collected clearly demonstrated that the karstic groundwater in the region was recharged from the local meteorological water. The tritium activity in the samples was found to be in between 3 and 4 TU, falling in the range of the 3H activity in the local precipitation and thus meaning that the traveling of recharge water to the resurgences was very short. Concentrated and diffuse allogenic recharges seem to be important sources of karstic groundwater in the study region. Water in the karstic aquifers could be classified into three types as: (a) water from karstic areas with dense vegetation cover that causes DIC be depleted in carbon 13 (13δ<?12‰ vs. Pee Dee Belemnite standard of Vienna, VPDB); (b) water from karstic areas with poor vegetation cover that originates DIC with carbon 13 composition ranging from ?11 to ?12‰; and (c) surface water from lakes, springs and rivers that has DIC with enriched carbon 13 (δ13C >?10‰). This implies that there are several sources of carbon dioxide contributing to the DIC in water of the karstic aquifers in the study region. Among other potential sources, the atmospheric CO2, CO2 from carbonate rock dissolution, biomineralization of soil organic matters and plant roots respiration seem to be important sources of the DIC in the waters of this region. The results show high vulnerability towards anthropogenic contaminants of karstic groundwater in the study region. 相似文献
62.
个旧锡矿高松矿田综合信息矿产预测 总被引:13,自引:1,他引:13
个旧超大型锡铜多金属矿床是我国和世界上重要的锡产地,近年来面临严重的资源危机。通过分析个旧锡矿高松矿田的地质、地球化学、地球物理等信息特征,用统计排序法和地质统计学方法解决了断裂、褶皱、地层、花岗岩等定性信息的量化、分级,用分维确定了考虑线性和面状因素的最佳信息单元大小,利用以Shannon信息论基本原理为基础的分层次自相似信息量加和法在信息类型内部和类型之间进行了信息的有机综合,得到了三级18个预测区,经云南锡业公司工程和已知矿区验证,取得了很好的效果。 相似文献
63.
64.
柴达木盆地三湖地区第四系蕴藏着巨大的生物气资源,目前已探明加控制天然气储量接近3×1011m3。更新世时期,柴达木盆地的湖相沉积主要分布在三湖(吉乃尔湖、涩聂湖和达布逊湖)地区,自山前至盆地中心依次发育了冲积扇、河流三角洲和湖相沉积,其中湖相沉积分布最为广泛。早更新世湖相沉积开始形成,中更新世湖相沉积扩张并且达到鼎盛,晚更新世湖相沉积开始萎缩并形成盐湖沉积。中、早更新世冰川的出现和青藏高原的崛起使柴达木盆地的古气候变得干旱寒冷,沉积水体温度较低,盐度较高。本区第四纪独特的沉积环境是形成大型生物气藏最重要的地质条件。高盐度的水体环境减缓了有机质的降解速度,长期的低温条件抑制了甲烷菌的活动,避免了沉积有机质在沉积浅埋阶段的过量消耗,推迟了生物产气的高峰期。而三湖地区巨厚的第四系暗色泥岩和频繁发育的砂岩提供了充足的气源条件和构成了良好的生储盖组合。 相似文献
65.
德国地震监测系统简介 总被引:1,自引:1,他引:0
1 德国地震监测系统德国的地震监测工作由德国联邦地学与自然资源研究院(BGR)负责,具体工作由格拉芬堡地震台阵(GRF)、德国区域地震台网(GRSN)、格拉芬堡地震观测中心(SZGRF)和试验地震观测台阵(GERESS)完成。图1 格拉芬堡地震台阵和德国区域地震台网台站分布格拉芬堡地... 相似文献
66.
Søren Jessen Flemming Larsen Dieke Postma Pham Hung Viet Nguyen Thi Ha Pham Quy Nhan Dang Duc Nhan Mai Thanh Duc Nguyen Thi Minh Hue Trieu Duc Huy Tran Thi Luu Dang Hoang Ha Rasmus Jakobsen 《Applied Geochemistry》2008
To study the geological control on groundwater As concentrations in Red River delta, depth-specific groundwater sampling and geophysical logging in 11 monitoring wells was conducted along a 45 km transect across the southern and central part of the delta, and the literature on the Red River delta’s Quaternary geological development was reviewed. The water samples (n = 30) were analyzed for As, major ions, Fe2+, H2S, NH4, CH4, δ18O and δD, and the geophysical log suite included natural gamma-ray, formation and fluid electrical conductivity. The SW part of the transect intersects deposits of grey estuarine clays and deltaic sands in a 15–20 km wide and 50–60 m deep Holocene incised valley. The NE part of the transect consists of 60–120 m of Pleistocene yellowish alluvial deposits underneath 10–30 m of estuarine clay overlain by a 10–20 m veneer of Holocene sediments. The distribution of δ18O-values (range −12.2‰ to −6.3‰) and hydraulic head in the sample wells indicate that the estuarine clay units divide the flow system into an upper Holocene aquifer and a lower Pleistocene aquifer. The groundwater samples were all anoxic, and contained Fe2+ (0.03–2.0 mM), Mn (0.7–320 μM), SO4 (<2.1 μM–0.75 mM), H2S (<0.1–7.0 μM), NH4 (0.03–4.4 mM), and CH4 (0.08–14.5 mM). Generally, higher concentrations of NH4 and CH4 and low concentrations of SO4 were found in the SW part of the transect, dominated by Holocene deposits, while the opposite was the case for the NE part of the transect. The distribution of the groundwater As concentration (<0.013–11.7 μM; median 0.12 μM (9 μg/L)) is related to the distribution of NH4, CH4 and SO4. Low concentrations of As (?0.32 μM) were found in the Pleistocene aquifer, while the highest As concentrations were found in the Holocene aquifer. PHREEQC-2 speciation calculations indicated that Fe2+ and H2S concentrations are controlled by equilibrium for disordered mackinawite and precipitation of siderite. An elevated groundwater salinity (Cl range 0.19–65.1 mM) was observed in both aquifers, and dominated in the deep aquifer. A negative correlation between aqueous As and an estimate of reduced SO4 was observed, indicating that Fe sulphide precipitation poses a secondary control on the groundwater As concentration. 相似文献
67.
68.
玄武岩—水相互作用的溶解机理研究 总被引:11,自引:0,他引:11
在常温常压排除大气干扰的封闭体系条件下,将一定粒度的玄武岩样品浸泡在不同酸度的水溶液里,研究玄武岩-水相互作用过程中元素释放和溶液酸度的变化情况。结果发现:(1)经过一段时间后,溶液中主要元素的浓度趋向平衡;(2)溶液酸度发生明显变化,即不论反应初始溶液是碱性的还是酸性的,最终都将趋于中性,我们把此现象称为溶液的中性化效应。根据溶液中溶解组分的浓度和样品表面组成的XPS测定结果,提出玄武岩在碱性和酸性溶液中不同的溶解机理。 相似文献
69.
波流共同作用下废黄河河口水下三角洲地形演变预测模式 总被引:9,自引:0,他引:9
通过对废黄河河口水下三角洲海域水文、泥沙、沉积和地形的调查分析,对组成水下三角洲-10--15m以深的平坦海床、-5--10m间的水下斜坡、-5m以浅的近岸浅滩三个地貌单元的水动力特征以及在波流和潮流作用下底部泥沙冲刷率的横向分布进行计算分析,并建立了水下三角洲地形横向剖面地形的演变预测模式。结果表明,在三角洲不同地貌单元内。由于所处不同的水动力条件和底部泥沙特性,出现了不同的侵蚀状态,其中在-10--15m以深的平坦海床,除了3m以上的大浪外,水动力作用以强劲的潮流冲刷为主,目前已接近冲刷相对平衡的状态,在-5--10m间的水下斜坡,受波浪和潮流的共同作用,冲刷强度大,地形剖面呈继续平行后退状态;-5m以浅的近岸浅滩,潮流作用相对较弱,以波浪为滩面的剧低为主,水深线不断向岸方向移动、滩宽变窄;0m以上的潮间带滩地,则波浪和潮流作用均较弱,近岸高滩接近相对稳定状态,有利于海岸线的工程防护。 相似文献
70.
The objective of the present study is to develop a volume of fluid (VOF)-based two-phase flow model and to discuss the applicability of the model to the simulation of wave–structure interactions. First, an overview of the development of VOF-type models for applications in the field of coastal engineering is presented. The numerical VOF-based two-phase flow model has been developed and applied to the simulations of wave interactions with a submerged breakwater as well as of wave breaking on a slope. Numerical results are then compared with laboratory experimental data in order to verify the applicability of the numerical model to the simulations of complex interactions of waves and permeable coastal structures, including the effects of wave breaking. It is concluded that the two-phase flow model with the aid of the advanced VOF technique can provide with acceptably accurate numerical results on the route to practical purposes. 相似文献