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441.
随机检索是水文数据库重要的检索功能之一,由于检索要求的不确定性给软件开发带来一定的困难。以数据库SQL语言为基础,通过对语言的简化和提示性的模式化操作,建立了一种实用的随机检索模型。 相似文献
442.
443.
F. A. El-Awar J. W. Labadie T. B. M. J. Ouarda 《Stochastic Environmental Research and Risk Assessment (SERRA)》1998,12(4):247-266
: As with all dynamic programming formulations, differential dynamic programming (DDP) successfully exploits the sequential
decision structure of multi-reservoir optimization problems, overcomes difficulties with the nonconvexity of energy production
functions for hydropower systems, and provides optimal feedback release policies. DDP is particularly well suited to optimizing
large-scale multi-reservoir systems due to its relative insensitivity to state-space dimensionality. This advantage of DDP
encourages expansion of the state vector to include additional multi-lag hydrologic information and/or future inflow forecasts
in developing optimal reservoir release policies. Unfortunately, attempts at extending DDP to the stochastic case have not
been entirely successful. A modified stochastic DDP algorithm is presented which overcomes difficulties in previous formulations.
Application of the algorithm to a four-reservoir hydropower system demonstrates its capabilities as an efficient approach
to solving stochastic multi-reservoir optimization problems. The algorithm is also applied to a single reservoir problem with
inclusion of multi-lag hydrologic information in the state vector. Results provide evidence of significant benefits in direct
inclusion of expanded hydrologic state information in optimal feedback release policies. 相似文献
444.
水文要素等值线图的自动绘制方法 总被引:2,自引:2,他引:2
降雨量、地下水位等水文要素常常需要用等值线图来直观地反应。介绍了反距离加权插值算法和三角网格的等值线追踪方法,并用面向对象的C 编程语言封装为TContour类。应用结果表明,TContour类的插值和追踪方法快速高效,算法描述简洁且易于维护升级,可广泛应用于水文要素等值线图的计算机自动绘制,同时大大方便了软件系统的系统集成。 相似文献
445.
分析了防汛指挥系统中水情信息采集系统的可靠性,并从理论上对描述水情信息采集系统模型的可靠性有关特征量参数进行了推导,最后得出了定量分析水情信息采集系统可靠性的方法和结论性公式。 相似文献
446.
西北内陆平原水资源开发引起的区域水文效应及其对环境的影响 总被引:10,自引:0,他引:10
内陆平原水资源主要的赋存形式是河流-含水层系统。无论是开发利用河水,还是开采地下水,都将引起区域性的水文效应——地下水位大幅度波动、泉水衰竭和水质恶化。在水资源开发条件下,人工绿洲与天然绿洲之间的水源分配是彼长此消的,防止生态环境退化的要义在于:从宏观上合理配置水源,并可靠地预测其可能引起的区域水文效应,防患于未然。 相似文献
447.
岷江上游森林水文效应研究 总被引:15,自引:1,他引:15
本文提出了用一般性流域水文模型研究森林水文效应的途径。得出在岷江上游地区随着覆盖率的下降年径流量减少、径流成份改变、年风分配更趋不均匀和洪峰流量增大的结论。在此基础上,预测了岷江上游地区水源涵养林建设的水文效益与前景。 相似文献
448.
W. Kron E. J. Plate J. Ihringer 《Stochastic Environmental Research and Risk Assessment (SERRA)》1990,4(4):255-276
A geomorphological study at the confluence of the Danube and the Isar in Bavaria required long series of daily discharges in both rivers. A model that generates simultaneous correlated streamflows in both rivers was developed and tested. The model is a modified shot noise model, first developed by Treiber (1975) for a single river, that was adapted to two rivers. It generates correlated pulses of events that produce flow for each river, and these pulses are then convoluted with a river specific systems function. The model, after being calibrated for the two rivers on the basis of 85 years of records, yields artificial series of discharges, in which the statistical properties of the historical records are reproduced. The performance of the model was tested with 20 generated series each 100 years long. 相似文献
449.
We assess the ability of multivariate statistical analyses applied to event hydrographs parameters, to characterize a catchment hydrological behaviour. Motivation for such an approach lies in the fact that streamflow records have yet to be exploited to their full potential towards hydrological interpretation and can be used to infer a catchment state of connectivity from a qualitative standpoint. We have therefore processed 96 event hydrographs from a small headwater temperate humid forested catchment using principal component analysis, variation partitioning and classification tree analysis. These techniques prove to be promising in discriminating contrasted types of hydrologic responses (e.g. low‐ vs high‐magnitude events, slow vs quick timing events), identifying the main hydro‐meteorological variables that control these responses and determining thresholds values of the hydro‐meteorological variables leading to a switch between catchment response types. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
450.
To aid prediction of the flow hydrograph in a basin with limited data, a practical approach to determining a regionalized Clark instantaneous unit hydrograph (IUH) model is presented. The proposed model is described in terms of the synthetic time–area concentration curve, the concentration time, and a special regional similarity value that is valid in the whole basin. The latter was estimated from a Monte Carlo testing procedure based on the normal probability distribution of transformed regional similarity values composed of the time of concentration and the storage coefficient in gauged basins. The time–area concentration curve and the concentration time were calculated from a rational equation as in conventional methods. The method of transformation adopted was the Box–Cox power transformation, which is known to make non‐normal values resemble normal data. By introducing the regional similarity value into a Clark IUH, a statistically best estimate of IUH for given data conditions and its quantified degree of uncertainty were realized. The Wi River basin in Korea was used to test the applicability of the regionalized Clark IUH. The performance of the suggested methodology was evaluated by assuming an ungauged sub‐basin at the site. The results showed that the IUH model developed in this work was an effective tool, predicting a reliable hydrograph within the study area even though only limited data were available. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献