全文获取类型
收费全文 | 11017篇 |
免费 | 1002篇 |
国内免费 | 1176篇 |
专业分类
测绘学 | 3528篇 |
大气科学 | 970篇 |
地球物理 | 1223篇 |
地质学 | 3007篇 |
海洋学 | 604篇 |
天文学 | 33篇 |
综合类 | 1246篇 |
自然地理 | 2584篇 |
出版年
2024年 | 41篇 |
2023年 | 110篇 |
2022年 | 309篇 |
2021年 | 385篇 |
2020年 | 394篇 |
2019年 | 422篇 |
2018年 | 304篇 |
2017年 | 512篇 |
2016年 | 465篇 |
2015年 | 515篇 |
2014年 | 588篇 |
2013年 | 787篇 |
2012年 | 638篇 |
2011年 | 733篇 |
2010年 | 526篇 |
2009年 | 541篇 |
2008年 | 552篇 |
2007年 | 662篇 |
2006年 | 625篇 |
2005年 | 575篇 |
2004年 | 583篇 |
2003年 | 449篇 |
2002年 | 406篇 |
2001年 | 332篇 |
2000年 | 275篇 |
1999年 | 261篇 |
1998年 | 231篇 |
1997年 | 177篇 |
1996年 | 166篇 |
1995年 | 110篇 |
1994年 | 129篇 |
1993年 | 96篇 |
1992年 | 83篇 |
1991年 | 52篇 |
1990年 | 47篇 |
1989年 | 35篇 |
1988年 | 28篇 |
1987年 | 21篇 |
1986年 | 10篇 |
1985年 | 4篇 |
1984年 | 5篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1979年 | 2篇 |
1978年 | 1篇 |
1977年 | 2篇 |
1976年 | 1篇 |
1975年 | 2篇 |
1973年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 12 毫秒
991.
重庆市沥鼻峡背斜盐井矿区龙潭组沉积特征及聚煤规律 总被引:1,自引:0,他引:1
通过对重庆市沥鼻峡背斜盐计矿区含煤地层研究,探讨了矿区龙潭组的沉积特征和聚煤规律,得出矿区龙潭组为泻湖-海湾-潮坪沉积体系,成煤时期的不同沉积环境,聚煤沉降幅度小,沉积速度和物质补偿均衡,有利于泥炭堆积,因此矿区含煤层数、煤层厚度较稳定,该区处于华蓥山潮坪地带,是龙潭期聚煤中心之一。 相似文献
992.
Jin Yaqiu 《Frontiers of Earth Science》2007,1(3):284-298
This paper briefly presents the research progress of the State Major Basic Research Project 2001CB309400, “Theory and Application
for Retrieval and Fusion of Spatial and Temporal Quantitative Information from Complex Natural Environment”. Based on the
rapid advancement of synthetic aperture radar (SAR) imagery technology, information theory of fully polarimetric scattering
and applications in polarimetric SAR remote sensing are developed. To promote the modeling of passive microwave remote sensing,
the vector (polarized) radiative transfer theory (VRT) of complex natural media such as inhomogeneous, multi-layered and 3-dimensional
VRT is developed. With these theoretical progresses, data validation and retrieval algorithms for some typical events and
characteristic parameters of earth terrain surfaces, atmosphere, and oceans from operational and experimental remote sensing
satellites are studied. Employing remote sensing, radiative transfer simulation, geographic information systems (GIS), land
hydrological process, and data assimilation, the Chinese land data assimilation system (CLDAS) is established. Towards the
future development of China’s microwave meteorological satellites, employing remote sensing data of currently available SSM/I
(special sensor microwave/imager), AMSU (advanced microwave sounding unit), MTI (microwave temperature imager), etc., with
ground-based measurements, several operational algorithms and databases for atmospheric precipitation, water vapor and liquid
water in clouds, and other hydrological/hydrological applications are developed. To advance China’s SAR and InSAR (interferometric
SAR) technologies, the image processing and analysis of ERS (European remote sensing), Radarsat SAR, and Chinese SAR, etc.,
the software platforms are accomplished. Based on the researches of multi-information fusion, some simulations, identification,
and information extractions of the targets from complex background clutter scenes are studied. Some experiments of radio wave
propagation in anomalous atmospheric status are also carried out.
Translated from Advances in Earth Science, 2007, 22(2): 111–125 [译自: 地球科学进展] 相似文献
993.
Data driven bivariate landslide susceptibility assessment using geographical information systems: a method and application to Asarsuyu catchment, Turkey 总被引:27,自引:0,他引:27
In the last decades, landslide hazard assessment has attracted many researchers' attention. A number of parameters are suggested to be responsible to quantitatively explain the mechanism of landslides; many of these parameters are very important and factual. However, some data types and models are site-specific and could not be applied to different locations. Furthermore, the data stored in continuous parameter maps are divided into a number of classes arbitrarily, depending on the vision of the expert. Basically, this division controls the result of bivariate analysis. Besides, the responsible portion of the parameter map controlling the mechanism is also weighted arbitrarily. Based on these two facts, the class boundaries put a prejudice on the produced susceptibility/hazard maps, which result in dependence on the knowledge of the user rather than being dependent on the data and the fact itself. The aim of this study is to refine the previously defined methods in a more data-dependent trend. To achieve this goal, two new concepts: seed cells and percentile maps are introduced. Seed cells are the zones that are considered to represent the best undisturbed morphological decision rules (conditions before landslide occurs) and would be achieved by adding a buffer zone to the crown and flank areas of the landslide. To quantitatively classify the input parameter maps, the data distributions of seed cells in the parameter maps are divided into a number of classes on the basis of their distribution's percentile break-points upon which the parameter maps are directly dependent on the seed cell distributions, hence to the data itself. 相似文献
994.
基于栅格空间信息定量化的湖南西部地区生态环境综合评价 总被引:18,自引:0,他引:18
以湖南西部地区为研究区域,采用遥感影像作为主要数据源,针对区域主要生态问题,利用栅格数据结构为主的数字环境模型,建立了生态环境质量综合评价模型. 对区域生态环境质量的空间分异格局进行了研究,通过将评价结果与数字高程模型迭加分析,研究了生态环境质量的垂直地带性分布规律,探索适合以山高坡陡为主要地貌特征的山区生态评价方法,结果显示,湖南西部地区生态环境综合指数呈正态分布,大部分地区环境质量属一般. 总体环境状况东南部好于西北部,河谷盆地优于山地. 研究表明,利用遥感和地理信息系统技术进行区域生态环境评价,具有数据采集快速、客观,评价和制图自动化,评价结果空间定位精度高,直观性与实用性强等优点. 相似文献
995.
996.
全国地质灾害趋势预测及预测图编制 总被引:13,自引:0,他引:13
区域地质灾害预测是地质灾害研究的难题。本文运用基于地理信息系统的风险评价方法对这一问题进行了探讨。将全国剖分为2700个单元,对地质灾害进行现状评价,并与已数字化的地质灾害图件进行单要素叠加,编制了全国地质现状等值线图,在现状评价基础上,对地质灾害进行趋势预测,将降雨条件、区域地震活动、区域地壳稳定程度、区域岩组条件和人类工程活动等作为区域地质灾害演变的因素,运用模糊综合评判模型进行综合评判,编制了1:600万中国地质灾害趋势预测图。 相似文献
997.
998.
网络环境下地质资料管理工作初探 总被引:1,自引:0,他引:1
本文基于当前形势下地质科学重点的转移以及计算机信息技术迅速发展为地质资料馆带来的影响,作者论述了地质资料管理工作的发展趋势,并指出提高管理人员的素质是做好地质资料管理工作的关键. 相似文献
999.
1000.
Citizens as sensors: the world of volunteered geography 总被引:62,自引:0,他引:62
Michael F. Goodchild 《GeoJournal》2007,69(4):211-221
In recent months there has been an explosion of interest in using the Web to create, assemble, and disseminate geographic information provided voluntarily by individuals. Sites such as Wikimapia and OpenStreetMap are empowering citizens to create a global patchwork of geographic information, while Google Earth and other virtual globes are encouraging volunteers to develop interesting applications using their own data. I review this phenomenon, and examine associated issues: what drives people to do this, how accurate are the results, will they threaten individual privacy, and how can they augment more conventional sources? I compare this new phenomenon to more traditional citizen science and the role of the amateur in geographic observation. 相似文献