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961.
Bjerhammar球面单层密度时间变化的实用解算理论 总被引:1,自引:1,他引:0
申重阳 《大地测量与地球动力学》1999,19(2):9-16
研究了Bjerhammar球面单层密度时变实用解算理论和稳定算法。从利用重复大地测量数据联合确定Bjerhammar球面单层密度时变基本理论出发,推导了不同Bjerhammar球面上q*t和δW*t之间的一般解式;分析研究了q*t的迭代求解过程和收敛特性,得出其收敛稳定性很大程度上取决于R值的结论,同时给出了界限R的关系式;提出了解求q*t的分步迭代算法,该算法从理论上解决了以前算法存在的收敛稳定问题(R较小时),并指出:地表观测点qt的确定应遵循匹配处理准则,即各观测点数据应蕴含相同物理过程。最后给出了q*t的精度评估公式。 相似文献
962.
Ida K. Westerberg Giuliano Di Baldassarre Keith J. Beven Gemma Coxon Tobias Krueger 《水文科学杂志》2020,65(Z2):2001-2003
ABSTRACTErtsen discusses the representation of reality and uncertainty in our paper, raising three critical points. In response to the first, we agree that discussion of different interpretations of the concept of uncertainty is important when developing perceptual models – making different uncertainty interpretations explicit was a key motivation behind our method. Secondly, we do not, as Ertsen suggests, deny anyone who is not a “certified” scientist to have relevant knowledge. The elicitation of diverse views by discussing perceptual models is a basis for open discussion and decision making. Thirdly, Ertsen suggests that it is not useful to treat socio-hydrological systems as if they exist. We argue that we act as “pragmatic realists” in most practical applications by treating socio-hydrological systems as an external reality that can be known. But the uncertainty that arises from our knowledge limitations needs to be recognized, as it may impact on practical decision making and associated costs. 相似文献
963.
Milan Stojković Jasna Plavšić Stevan Prohaska Dragutin Pavlović Jovan Despotović 《水文科学杂志》2020,65(3):387-400
ABSTRACTClimate change projections of precipitation and temperature suggest that Serbia could be one of the most affected regions in southeastern Europe. To prepare adaptation measures, the impact of climate changes on water resources needs to be assessed. Pilot research is carried out for the Lim River basin, in southeastern Europe, to predict monthly flows under different climate scenarios. For estimation of future water availability, an alternative approach of developing a deterministic-stochastic time series model is chosen. The proposed two-stage time series model consists of several components: trend, long-term periodicity, seasonality and the stochastic component. The latter is based on a transfer function model with two input variables, precipitation and temperature, as climatic drivers. The Nash-Sutcliffe model efficiency for the observed period 1950–2012 is 0.829. The model is applied for the long-term hydrological prediction under the representative concentration pathway (RCP) emissions scenarios for the future time frame 2013–2070. 相似文献
964.
ABSTRACTPower plants often use river waters for cooling purposes and can be sensitive to droughts and low flows. Water quality is also a concern, due to algal blooms and sediment loads that might clog filters. We assessed the impacts of droughts on river flow and water quality from the point of view of power plant operation. The INCA (INtegrated CAtchment) water quality model was coupled with a climate model to create a dataset of flow and water quality time series, using the River Trent (UK) as a case study. The result hints to a significant decrease in flows and an increase in phosphorus concentrations, potentially enhancing algal production. Power plants should expect more stress in the future based on the results of this study, due to reduced cooling water availability and decreasing upstream water quality. This issue might have serious consequences also on the whole national power network. 相似文献
965.
ABSTRACTWater indicators and indices are useful tools to assess river basin performance, that is, to measure whether the basin operates satisfactorily under a wide range of possible future demands and hydrological conditions. Spanish regulations assess the performance of water demands by using reliability indicators (RIs), established by law in 2008. This article raises the possibility of updating RIs by comparing them with sustainability indicators (SIs). SIs are widely used for the assessment of river basin performance and several policy scenarios. We applied a water allocation model to the Guadiana River basin in Spain to compare indicators under three scenarios. The study was framed within the science of socio-hydrology, combining the physical environment of a water system with its influence on social aspects. SIs gave better results than RIs when comparing future scenarios. We also propose the introduction of a vulnerability indicator into Spanish regulations. 相似文献
966.
ABSTRACT In many places, magnitudes and frequencies of floods are expected to increase due to climate change. To understand these changes better, trend analyses of historical data are helpful. However, traditional trend analyses do not address issues related to shifts in the relative contributions of rainfall versus snowmelt floods, or in the frequency of a particular flood type. We present a novel approach for quantifying such trends in time series of floods using a fuzzy decision tree for event classification and applied it to maximal annual and seasonal floods in 27 alpine catchments for the period 1980–2014. Trends in flood types were studied with Sen’s slope and double mass curves. Our results reveal a decreasing number of rain-on-snow and an increasing number of short rainfall events in all catchments, with flash floods increasing in smaller catchments. Overall, the results demonstrate the value of incorporating a fuzzy flood-type classification into flood trend analyses. 相似文献
967.
Isaac Larbi Emmanuel Obuobie Anne Verhoef Stefan Julich Karl-Henz Feger Aymar Yaovi Bossa 《水文科学杂志》2020,65(13):2196-2209
ABSTRACT The need for a detailed investigation of the Vea catchment water balance components cannot be overemphasized due to its accelerated land-cover dynamics and the associated impacts on the hydrological processes. This study assessed the possible consequences of land-use change scenarios (i.e. business as usual, BAU, and afforestation for the year 2025) compared to the 2016 baseline on the Vea catchment’s water balance components using the Soil and Water Assessment Tool (SWAT) model. The data used include daily climate and discharge, soil and land use/land cover maps. The results indicate that the mean annual water yield may increase by 9.1% under the BAU scenario but decrease by 2.7% under the afforestation scenario; actual evapotranspiration would decrease under BAU but increase under afforestation; and groundwater recharge may increase under both scenarios but would be more pronounced under the afforestation scenario. These outcomes highlight the significance of land-cover dynamics in water resource management and planning at the catchment. 相似文献
968.
山东省冠县城区土地定级实践研究 总被引:4,自引:0,他引:4
以GIS为基础,利用土地定级估价信息系统,确定山东省冠县城区土地分等定级的因素、因子及其权重,在此基础上计算各因素、因子的分值和土地定级单元分值,然后根据单元分值对土地级别进行初步划分并实地校核,最后对定级成果进行分析研究。 相似文献
969.
970.
酒泉、嘉峪关地域城镇系统的空间规模结构研究 总被引:6,自引:0,他引:6
受干旱区自然地理、人口发展与分布等特殊条件的制约,酒泉、嘉峪关地域城镇系统的空间规模结构呈现“中小市镇、多中心”的特征。针对这种状况,空间规模结构的研究和规划,应注重建构多中心的地域城镇系统,带动地域整体发展要促进相邻城市间、城市与境内或周边单位间的空间关联及与近郊集镇的融合,推动城乡一体化应突出酒泉-嘉峪关复合城市的中心地位,强化敦煌市的规模和职能,保证玉门市区持续发展并尽快发展玉门镇,积极发展其他小城镇。 相似文献