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41.
Hilary McMillan Jim Freer Florian Pappenberger Tobias Krueger Martyn Clark 《水文研究》2010,24(10):1270-1284
In order to quantify total error affecting hydrological models and predictions, we must explicitly recognize errors in input data, model structure, model parameters and validation data. This paper tackles the last of these: errors in discharge measurements used to calibrate a rainfall‐runoff model, caused by stage–discharge rating‐curve uncertainty. This uncertainty may be due to several combined sources, including errors in stage and velocity measurements during individual gaugings, assumptions regarding a particular form of stage–discharge relationship, extrapolation of the stage–discharge relationship beyond the maximum gauging, and cross‐section change due to vegetation growth and/or bed movement. A methodology is presented to systematically assess and quantify the uncertainty in discharge measurements due to all of these sources. For a given stage measurement, a complete PDF of true discharge is estimated. Consequently, new model calibration techniques can be introduced to explicitly account for the discharge error distribution. The method is demonstrated for a gravel‐bed river in New Zealand, where all the above uncertainty sources can be identified, including significant uncertainty in cross‐section form due to scour and re‐deposition of sediment. Results show that rigorous consideration of uncertainty in flow data results in significant improvement of the model's ability to predict the observed flow. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
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Stormwater infiltration systems are a popular method for urban stormwater control. They are often designed using an assumption of one‐dimensional saturated outflow, although this is not very accurate for many typical designs where two‐dimensional (2D) flows into unsaturated soils occur. Available 2D variably saturated flow models are not commonly used for design because of their complexity and difficulties with the required boundary conditions. A purpose‐built stormwater infiltration system model was thus developed for the simulation of 2D flow from a porous storage. The model combines a soil moisture–based model for unsaturated soils with a ponded storage model and uses a wetting front‐tracking approach for saturated flows. The model represents the main physical processes while minimizing input data requirements. The model was calibrated and validated using data from laboratory 2D stormwater infiltration trench experiments. Calibrations were undertaken using five different combinations of calibration data to examine calibration data requirements. It was found that storage water levels could be satisfactorily predicted using parameters calibrated with either data from laboratory soils tests or observed water level data, whereas the prediction of soil moistures was improved through the addition of observed soil moisture data to the calibration data set. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
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南黄海辐射沙洲主要潮沟的变迁 总被引:6,自引:1,他引:6
黄海军 《海洋地质与第四纪地质》2004,24(2):1-8
利用1966年和1977年海图、1995年和2000年合成孔径雷达影像,结合1980年以来的陆地卫星影像和2000年的岸滩实测剖面资料对南黄海辐射沙洲区主要潮沟的位置进行了解译与分析,得出上述4个时期研究区内主要潮沟深泓线位置图。对不同时期潮沟深泓线位置图进行几何校准与叠加,对比潮沟深泓线的迁移。结果表明:潮沟具有往返周期性摆动的特点,短期摆动速度明显快于长期摆动,主沟槽最大变动速度达127m/a,而支沟槽变动速度更大。潮沟摆动与沙洲变化有明显的相关性,但两者间的关系较为复杂。辐射沙洲目前处于破碎、萎缩阶段,除沙洲中心及陆岸岸滩仍有淤积外,大部分沙洲处于侵蚀状况,同时沙洲有整体向陆迁移的趋势。 相似文献
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卫星高度计海上定标场及定标方法研究进展 总被引:1,自引:0,他引:1
介绍了卫星高度计定标中海面高度和后向散射系数的定标方法。在后向散射系数的定标中介绍了利用有源定标器和微波辐射计定标两种方法。结合卫星高度计的特点,提出了海上定标场选取所需注意的问题,并介绍了目前比较成功的几个定标场及其定标结果,旨在为我国今后发射的卫星高度计绝对定标和定标场的选取提供依据。 相似文献
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具有国际先进水平的CTD定标检测设备 总被引:1,自引:0,他引:1
在国家863计划的支持下,海洋技术研究成功研制了一套CTD仪器的校准设备,本文介绍了设备的组成,性能,设计经过与SBE设备进行了比较,表明该设备达到了EOCECTD设备的校准要求,同时,该设备是海洋技术研究所开发自有的高度CTD剖面仪的有力工具。 相似文献
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The radiometers on board the satellites ERS-1, TOPEX/Poseidon, ERS-2, GFO, Jason-1, and Envisat measure brightness temperatures at two or three different frequencies to determine the total columnal water vapor content and wet tropospheric path delay, a major correction to the altimeter range measurements. In order to asses the long-term stability of the path delay, the radiometers are calibrated against vicarious cold and hot references, against each other, and against several atmospheric models. Four of these radiometers exhibit significant drifts in at least one of the channels, resulting in yet unmodeled errors in path delay of up to 1 mm/year, thus limiting the accuracy at which global sea level rise can be inferred from the altimeter range measurements. 相似文献
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