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101.
Morten Rasch Birger Hansen Ole Humlum Niels Nielsen Peter Funch Stephen D. Gurney 《Geografisk tidskrift / udgivet af Bestyrelsen for Det Kongelige danske geografiske selskab》2013,113(1):143-159
188 new and previously published radiocarbon dates on Holocene material from Disko Bugt, central West Greenland, are presented together with relevant informations (laboratory number, place name, dated material, geografic coordinates, altitude and δ13C-value) about the dates. In October 1990 an automatic weather station was established at the Arctic station (65 °15′N,53 °31′W), Qeqertarsuaq (Godhavn), Central West Greenland. The Station register parameters each 20 min., and the parameters have been described in an earlier paper in this journal by Nielsen et al. (1995). The present paper summarises main points of the climate during 1996. Open system, or more correctly, hydraulic pingos, are genetically poorly understood. A continuing problem concerns their need for a perennial groundwater supply (intra- or sub-permafrost). This has to be maintained despite the existence of continuous permafrost in many areas where they are located. Recent work on Disko Island has suggested a new type of hydraulic pingo developing only in a “marsh environment”. It is argued that the marsh setting is not relevant to the formation of these features and that they are simply hydraulic pingos. Abstract A group of marsh initiated open system pingo remnants from the Iterdlagssûp kûgssua valley mouth, in Mellemfjord, Disko Island, Central West Greenland was described in Christiansen (1995). Gurney and Worsley (1997) state that the location of this group of pingo remnants in the Iterdlagssûp kûgssua valley mouth is of no relevance to their genesis, and that they presumably were the result of an assumed late Holocene sea level regression, causing permafrost to be established in the valley bottom. In this reply the arguments by Gurney and Worsley (1997) on the Iterdlagssûp kûgssua valley pingos are commented, and it is argued by way of sea level information, frost penetration and water supply that the special setting must indeed have caused pingo initiation and growth. Furthermore, the area has experienced a relative sea level rise during the late Holocene. 相似文献
102.
103.
水库渗漏是水电工程关注的核心问题之一,库水的大量漏失,不但可能使大坝蓄水达不到设计高度而影响工程效益,同时水流的渗透作用还会导致地基岩体的恶化,产生渗透破坏,影响大坝本身的安全.文章在定性分析的基础上,用有限差分方法评价水库的渗漏问题,计算了水库的渗流量,计算并优化了最佳铺盖长度,计算了基底水力坡度,因其量值较大,必须在渗流出口处采取反滤层等工程措施,给相关部门提供设计依据和决策参考. 相似文献
104.
增强型地热系统(Enhanced Geothermal System, EGS)是一种通过介质循环(水或CO2)来提取深部低渗、高温岩体中地热资源并将其用来发电及供暖的工程技术集成。水力压裂是EGS储层改造的主要方式, 储层改造的好坏直接关系到EGS最终的产能状况, 因此针对具体地质条件选择合适的水力压裂方案具有重要意义。本文基于大庆莺深2井的测井资料, 根据其地应力及岩性变化情况选定EGS开采潜力储层, 采用水平井及张开型压裂的储层改造方式, 对潜力储层进行了多种压裂方案数值模拟分析, 根据压裂模拟结果建立三维水热耦合模型, 进行了EGS发电潜力评估分析, 最终得出莺深2井EGS开采的最优压裂方案和开采方案。研究结果得出:水力裂缝的几何性质主要受地应力、支撑剂粒径和砂比影响, 在EGS中宜采用低砂比、阶梯式的泵注程序。同时, 在采用一注两抽的三水平井开采模式下, 10条裂缝的最优注入速率是30kg,s-1, 运行20a的发电量是0.60~1.23MW。 相似文献
105.
Applied flood risk analyses, especially in urban areas, very often pose the question how detailed the analysis needs to be
in order to give a realistic figure of the expected risk. The methods used in research and practical applications range from
very basic approaches with numerous simplifying assumptions up to very sophisticated, data and calculation time demanding
applications both on the hazard and on the vulnerability part of the risk. In order to shed some light on the question of
required model complexity in flood risk analyses and outputs sufficiently fulfilling the task at hand, a number of combinations
of models of different complexity both on the hazard and on the vulnerability side were tested in a case study. The different
models can be organized in a model matrix of different complexity levels: On the hazard side, the approaches/models selected
were (A) linear interpolation of gauge water levels and intersection with a digital elevation model (DEM), (B) a mixed 1D/2D
hydraulic model with simplifying assumptions (LISFLOOD-FP) and (C) a Saint-Venant 2D zero-inertia hyperbolic hydraulic model
considering the built environment and infrastructure. On the vulnerability side, the models used for the estimation of direct
damage to residential buildings are in order of increasing complexity: (I) meso-scale stage-damage functions applied to CORINE
land cover data, (II) the rule-based meso-scale model FLEMOps+ using census data on the municipal building stock and CORINE
land cover data and (III) a rule-based micro-scale model applied to a detailed building inventory. Besides the inundation
depths, the latter two models consider different building types and qualities as well as the level of private precaution and
contamination of the floodwater. The models were applied in a municipality in east Germany, Eilenburg. It suffered extraordinary
damage during the flood of August 2002, which was well documented as were the inundation extent and depths. These data provide
an almost unique data set for the validation of flood risk analyses. The analysis shows that the combination of the 1D/2D
model and the meso-scale damage model FLEMOps+ performed best and provide the best compromise between data requirements, simulation
effort, and an acceptable accuracy of the results. The more detailed approaches suffered from complex model set-up, high data
requirements, and long computation times. 相似文献
106.
油气在盆地中产生和运移过程中,水动力因素起着重要的控制作用[1],如何确定这一作用的实际影响,是一个值得研究的问题。通过数学推导,得出储层中的稳态油层和非稳态油层两种情况下的水动力理论模型,并且对水动力圈闭、深度-压力系统和流体势等作出理论模拟,将其用于油气勘探中,结果与实际情况较相符。 相似文献
107.
108.
Large quantities of leachate-contaminated lateritic soil results from dump yards in the southwest coast of India. These dump yards receive large quantities of municipal solid waste which includes chemical, industrial and biomedical wastes. Large areas of land are currently being used for this purpose. An extensive laboratory testing program was carried out to determine the compaction characteristics and hydraulic conductivity of clean and contaminated lateritic soil. Batch tests were used to study the immediate effect of leachate contamination on the properties of lateritic soil. Contaminated specimens were prepared by mixing the lateritic soil with leachate in the amount of 5%, 10% and 20% by weight to vary the degree of contamination. The results indicated a small reduction in maximum dry density and an increase in hydraulic conductivity due to leachate-contamination. The change induced by chemical reaction in the microstructure of the soil was studied by scanning electron microscope before and after contamination of soil with leachate. The structure of the leachate contaminated soil sample appeared to be aggregated in scanning electron microscope analysis. The aggregated structure increases the effective pore space and thus increases the hydraulic conductivity. Fifty percent increase in hydraulic conductivity was observed for specimens prepared at standard Proctor density and mixed with 20% leachate. Compaction characteristics did not change much with the presence of leachate up to 10%. With 20% leachate the maximum dry density decreased slightly indicating excess leachate in the soil. However the changes are not significant. 相似文献
109.
110.
桂阳宝山西矿群孔抽水试验曲线分析 总被引:1,自引:0,他引:1
桂阳宝山矿区主要含水层壶天群及梓门桥组白云岩,与桂阳县城联成一坎,据水文地质特征,矿区至县城可划分为3个水文地质单元,在矿区西矿段距县城1.1km以上的K23孔连续抽水55天,抽取水最21.1万吨,主孔水位自322.95m降至267.45m,主孔周围有29个观测孔,控制面积4.6km~2,圈定的降落漏斗为椭圆形,面积0.5km~2。通过对各种试验数据与曲线分析说明试验区含水体主要补给源为降雨渗入,在西矿水位降至267m时,与县城之间无水力联系。 相似文献