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911.
为了满足用户对数据现势性的要求,应当保证道路数据的及时准确更新,其关键是对同名道路数据进行匹配。鉴于对道路进行整体分析,道路的形状特征变得尤为重要,因此提出了基于复杂网络的道路匹配方法。该方法利用复杂网络理论分析每条道路的形状特性,得到相关的形状参数,再结合距离、方向等指标的参数计算得到总的相似度,从而选出最佳的匹配道路。这种方法计算简单,对道路的形状特征能很好地描述,并能很快地从候选匹配道路中识别出匹配道路。实验结果表明,将该方法用于道路匹配具有较高的准确率和可靠性。 相似文献
912.
ABSTRACTThe cartographic identification and characterization of urban settlements is problematic, particularly in varied areas or in large geographical extensions. This is due to the divergence between morphological area structures and data attribution, which is generally available at the level of administrative units. Most existing experiences focus on small regions or use indirect data, from which only indirect information can be derived. This paper proposes an identification of urban settlements in the European Union space, which combines urban population and shape through geographic information system (GIS) techniques. For that purpose, 1 km2 cells with associated population data are used. A procedure is developed establishing three different types of urban settlements, according to population and population density values: high-density urban clusters, small and medium-sized towns, and very small towns. A validation of this procedure is performed using direct survey from local experts in 10 selected study areas. The final results show that 78,307 urban settlements can be identified: 88.17% of them are classified as “very small towns,” 10.75% as “small and medium-sized towns,” and 1.08% as high-density urban clusters. This exercise generates new information for the European Union and surrounding countries, and yields the basis for further research. All GIS operations are performed using vector layers, which is not usual in large-area regional studies. 相似文献
913.
The settling potential of fine sediment is known to be influenced by particle size, shape, density and porosity, and is commonly predicted using Stokes's law, despite its known limitations for modelling the behaviour of natural particles. In order to develop an improved understanding of the potential for fine sediment to settle out of suspension or undergo transport by hydraulic processes, it is important to examine the role of particle structure in detail. In this study, stepwise regression was used to identify which structural properties of particles exert an important control on fine sediment behaviour in river systems. The presence of composite particles and their associated particle size, porosity and fractal dimension were shown to be the most important controls on settling potential. Composite particles that form in the aquatic environment (flocs) were shown to have significantly different form and behaviour from composite particles of terrestrial origin (aggregates). Importantly, it was demonstrated that particle structure and behaviour exhibited consistencies between contrasting river catchments in different locations. An understanding of the mechanisms responsible for the formation of composite particles is viewed as providing a valuable input to efforts to model the mobilisation, transport and fate of fine sediment. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
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915.
卢婷 《大地测量与地球动力学》2016,36(10):907-911
利用四川区域地震台网的数字波形资料以及中国地震台网中心的有关震相数据,选取互相衔接的3段地震波的几何衰减模型,利用基于遗传算法的Atkinson和Mereu方法,反演得到四川攀枝花-西昌地区的介质品质因子Q(f),并采用Brune的ω平方模型约束震源位移谱,使用Moya方法联合多台多地震数据求得该地区各地震台站的场地响应。结果显示,2008-05~2013-12期间攀西地区介质衰减模型为Q(f)=94.4f0.665 9,2014-01~2015-06期间该地区介质衰减模型为Q(f)=83.9f0.719 6,两个时间段的反演结果十分接近,且均呈现出低Q0和较高衰减系数γ的特点,即该地区地震波衰减明显偏高,同时Q对频率f的依赖较大;场地响应方面,岩石台基对地震波信号在不同频率点的放大作用不同,其中MGU、PGE和SMK地震台场地增益较大,YYU、YYC地震台场地放大倍数在1~2之间平稳变化,LGH地震台场地响应随频率增大而快速衰减。结合上述计算结果推测,攀西地区构造活跃、上地壳结构极不均匀、地震波能量衰减强烈是造成该区域Q0低异常的主要原因。 相似文献
916.
Stephen E. White 《The Professional geographer》1985,37(1):28-35
The macro-level activity spaces of residents in Atlanta, Boston, Cleveland, Denver, Kansas City, and San Francisco differ significantly in areal extent, compactness and shape. They fail to conform closely with the pattern expected based on gravity formulations of distance to and size of potential destinations. Activity space is defined as the percentage of respondents in each city who have visited thirty other metro areas within a decade. Maps of residuals from regression indicate that the major visitation flows from each city are neither random nor concentric but spatially concentrated and easily identified. Macro-level activity spaces may be useful in understanding interregional migration flow bias. 相似文献
917.
918.
Corene Matyas 《The Professional geographer》2007,59(2):158-172
Tropical cyclones (TCs) produce complex rainfall patterns that are difficult to predict due to atmospheric and land surface forcings. This study utilizes geographic information systems to spatially analyze radar returns and calculate several metrics that quantify the shapes of TC rain shields. Three stepwise discriminant analyses are performed to determine which of the shape metrics distinguish among TCs categorized by: intensity, distance traveled inland, and orientation of terrain encountered. Results confirm that TC rain shields often assume noncircular shapes. Utilizing shape indices to model rain shields could help produce TC rainfall forecasts that are more spatially accurate. 相似文献
919.
On three-dimensional geological modeling and visualization 总被引:9,自引:0,他引:9
WU Qiang & XU Hua . Department of Resource Exploitation Engineering China University of Mining Technology Beijing China . Beijing Institute of Petrochemical Technology Beijing China 《中国科学D辑(英文版)》2004,47(8):739-748
3D geological modeling and visualization are the key technique issues to implement the plan of 揇igital Earth? At present, the major difficulties in 3D geo-logical modeling are as follows[1—5]: (1) 3D spatial data are difficult to acquire. What 3D geological modeling of complex objects and visu-alization depend on is the original data. However, it is very difficult to establish 3D complex geological models when the sampled data are sparse and insuffi-cient, the seismic profile data are lack… 相似文献
920.