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地理信息系统所产生的问题,很大程度上受数据类型设计与数据表现方法的影响,由3类数据:状态、事件与证据组成的时态地理信息系统,对这种影响更为明显。已有的时空数据模型只描述状态(如快照序列模型)或只描述事件(如基于事件的时空数据模型),难以表达状态与事件间的因果关系。本文提出的基于Petri网的时空数据模型。能显式存储状态、事件以及状态与事件间的因果关系,其中Petri网的库所表达状态、变迁表达事件及有向弧表达状态与事件间的关系。最后用该模型对土地划拨中的变化进行了描述,表明能便于对事件和状态的查询,及对事件之间、状态之间以及事件与状态之间的时态关系的查询。 相似文献
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Bo Yang Minxuan Lan Zengli Wang Hanlin Zhou Hongjie Yu 《International journal of geographical information science》2020,34(9):1740-1764
ABSTRACT Accurate crime prediction can help allocate police resources for crime reduction and prevention. There are two popular approaches to predict criminal activities: one is based on historical crime, and the other is based on environmental variables correlated with criminal patterns. Previous research on geo-statistical modeling mainly considered one type of data in space-time domain, and few sought to blend multi-source data. In this research, we proposed a spatio-temporal Cokriging algorithm to integrate historical crime data and urban transitional zones for more accurate crime prediction. Time-series historical crime data were used as the primary variable, while urban transitional zones identified from the VIIRS nightlight imagery were used as the secondary co-variable. The algorithm has been applied to predict weekly-based street crime and hotspots in Cincinnati, Ohio. Statistical tests and Predictive Accuracy Index (PAI) and Predictive Efficiency Index (PEI) tests were used to validate predictions in comparison with those of the control group without using the co-variable. The validation results demonstrate that the proposed algorithm with historical crime data and urban transitional zones increased the correlation coefficient by 5.4% for weekdays and by 12.3% for weekends in statistical tests, and gained higher hit rates measured by PAI/PEI in the hotspots test. 相似文献
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The technique of incremental updating,which can better guarantee the real-time situation of navigational map,is the developing orientation of navigational road network updating.The data center of vehicle navigation system is in charge of storing incremental data,and the spatio-temporal data model for storing incremental data does affect the efficiency of the response of the data center to the requirements of incremental data from the vehicle terminal.According to the analysis on the shortcomings of several ... 相似文献
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2001-2010年蒙古国MODIS-NDVI时空变化监测分析 总被引:2,自引:0,他引:2
利用2001 - 2010年的空间分辨率为1km的MODIS-NDVI数据,以蒙古国为研究区域,利用最大值合成法、均值法与差值法、一元线性回归等方法,分析了不同季节下植被覆盖的年内变化、年际变化与波动趋势、空间变化特征.结果表明:M(ODIS- NDVI对植被的生长变化具有较高的敏感度,可有效应用于植被生态的评估和监测... 相似文献
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基于1954—2017年中国2426个台站的日雨凇资料分析了中国雨凇日数的气候特征和变化特征。中国的雨凇主要出现在新疆和中国的103°E以东地区,主要区域有三个,分别是陕甘宁三省(区)交界、河南—湖北东部、江西—湖南—贵州—云贵川交界,其中第三个区域范围最大、雨凇日数最多,平均每年单站可达5~50 d,海拔3 047 m的峨眉山雨凇日数(128 d)为全国最多。黄河以南的雨凇区域内,海拔1000 m以上站点雨凇日数易多,峨眉山、南岳、威宁、庐山是我国雨凇日数最多的几个站。我国雨凇基本出现在9月至次年5月,最早出现最晚结束的区域在天山山脉、陕甘宁交界、云贵川交界站点。从范围大小、日数上均以江西—湖南—贵州—云贵川交界区域突出,该区域雨凇日数在出现时段内呈主峰型分布,出现时间主要集中在隆冬季节冷空气最活跃的1月中旬到2月上旬。三个主雨凇区的雨凇开始和结束日期无明显年代际差异,而日雨凇概率有明显的年代际变化特征,1961—2016年期间的前26年明显高于后30年。1961—2016年全国雨凇日数整体呈减少趋势,1990年后除贵州—湖南主雨凇区外,雨凇范围明显减小。 相似文献
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N. Stagli?i?S. Mati?-Skoko A. PallaoroR. Grgi?evi? M. Kraljevi?P. Tutman B. Dragi?evi?J. Dul?i? 《Estuarine, Coastal and Shelf Science》2011,94(3):263-271
Long-term interannual changes in abundance, biomass, diversity and structure of littoral fish assemblages were examined between 1993 and 2009 by experimental trammel net fishing up to six times per year, within the warm period - May to September, at multiple areas along the eastern Adriatic coast with the aim of testing for the consistency of patterns of change across a large spatial scale (∼600 km). The results revealed spatially consistent increasing trends of total fish abundance and biomass growing at an average rate of 15 and 14% per year, respectively. Of the diversity indices analysed, the same pattern of variability was observed for Shannon diversity, while Pielou evenness and average taxonomic distinctness measures Δ∗ and Δ+ showed spatial variability with no obvious temporal trends. Multivariate fish assemblage structure underwent a directional change displaying a similar pattern through time for all the areas. The structural change in fish assemblages generally involved most of the species present in trammel net catches. A large pool of fish species responsible for producing the temporal pattern of assemblage change was relatively different in each of the areas reflecting a large geographic range covered by the study. An analysis of 4 fish species (Symphodus tinca, Pagellus erythrinus, Mullus surmuletus, Scorpaena porcus) common to each of the study areas as the ones driving the temporal change indicated that there were clear increasing trends of their mean catches across the years at all the study areas. A common pattern among time trajectories across the spatial scale studied implies that the factor affecting the littoral fish assemblages is not localised but regional in nature. As an underlying factor having the potential to induce such widespread and consistent improvements in littoral fish assemblages, a more restrictive artisanal fishery management that has progressively been put in place during the study period, is suggested and discussed. 相似文献