首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   134篇
  免费   29篇
  国内免费   39篇
测绘学   34篇
大气科学   13篇
地球物理   16篇
地质学   93篇
海洋学   6篇
天文学   7篇
综合类   9篇
自然地理   24篇
  2024年   6篇
  2023年   3篇
  2022年   7篇
  2021年   8篇
  2020年   11篇
  2019年   12篇
  2018年   25篇
  2017年   17篇
  2016年   10篇
  2015年   12篇
  2014年   15篇
  2013年   10篇
  2012年   3篇
  2011年   8篇
  2010年   2篇
  2009年   5篇
  2008年   3篇
  2007年   11篇
  2006年   4篇
  2005年   4篇
  2004年   3篇
  2003年   3篇
  2002年   2篇
  2001年   4篇
  2000年   1篇
  1999年   2篇
  1998年   2篇
  1997年   4篇
  1995年   3篇
  1991年   1篇
  1988年   1篇
排序方式: 共有202条查询结果,搜索用时 15 毫秒
81.
ABSTRACT

Digital Earth has seen great progress during the last 19 years. When it entered into the era of big data, Digital Earth developed into a new stage, namely one characterized by ‘Big Earth Data’, confronting new challenges and opportunities. In this paper we give an overview of the development of Digital Earth by summarizing research achievements and marking the milestones of Digital Earth’s development. Then, the opportunities and challenges that Big Earth Data faces are discussed. As a data-intensive scientific research approach, Big Earth Data provides a new vision and methodology to Earth sciences, and the paper identifies the advantages of Big Earth Data to scientific research, especially in knowledge discovery and global change research. We believe that Big Earth Data will advance and promote the development of Digital Earth.  相似文献   
82.
ABSTRACT

Pushed by the Internet of Things (IoT) paradigm modern sensor networks monitor a wide range of phenomena, in areas such as environmental monitoring, health care, industrial processes, and smart cities. These networks provide a continuous pulse of the almost infinite activities that are happening in the physical space and are thus, key enablers for a Digital Earth Nervous System. Nevertheless, the rapid processing of these sensor data streams still continues to challenge traditional data-handling solutions and new approaches are being requested. We propose a generic answer to this challenge, which has the potential to support any form of distributed real-time analysis. This neutral methodology follows a brokering approach to work with different kinds of data sources and uses web-based standards to achieve interoperability. As a proof of concept, we implemented the methodology to detect anomalies in real-time and applied it to the area of environmental monitoring. The developed system is capable of detecting anomalies, generating notifications, and displaying the recent situation to the user.  相似文献   
83.
大数据时代城市地质信息的集群与产业化发展   总被引:1,自引:0,他引:1  
以城市地质调查成果为依托,深化城市地质信息的集群化与产业化,是顺应大数据时代发展的必然要求。阐述了大数据的基本特征、城市地质信息集群化与产业化的工作准则与技术途径;结合上海地区实践,探讨城市地质信息集群化与产业化的社会应用及服务领域开拓。  相似文献   
84.
吴德金  陈玲 《天文学报》2023,64(3):24-29
现代科学表明宇宙中99%以上的可观测物质都处于等离子体状态,从小尺度的微观粒子动力学集体过程与能量转换机制到大尺度的宇宙等离子天体结构状态与爆发活动现象,都是等离子天体物理学的研究课题.从宇宙演化历史、大尺度结构形成以及爆发活动现象等方面,系统地论述了等离子天体物理学在现代天文学发展以及现代等离子体宇宙观形成中的重要作用.同时,结合空间卫星科学探测研究及其对现代天文学的巨大影响,进一步阐述了地球磁层和日球层等空间等离子体实地探测研究在等离子天体物理学研究中所扮演的“天然实验室”的独特作用.  相似文献   
85.
Longitudinal mortality data with few deaths usually have problems of zero-inflation. This paper presents and applies two Bayesian models which cater for zero-inflation, spatial and temporal random effects. To reduce the computational burden experienced when a large number of geo-locations are treated as a Gaussian field (GF) we transformed the field to a Gaussian Markov Random Fields (GMRF) by triangulation. We then modelled the spatial random effects using the Stochastic Partial Differential Equations (SPDEs). Inference was done using a computationally efficient alternative to Markov chain Monte Carlo (MCMC) called Integrated Nested Laplace Approximation (INLA) suited for GMRF. The models were applied to data from 71,057 children aged 0 to under 10 years from rural north-east South Africa living in 15,703 households over the years 1992–2010. We found protective effects on HIV/TB mortality due to greater birth weight, older age and more antenatal clinic visits during pregnancy (adjusted RR (95% CI)): 0.73(0.53;0.99), 0.18(0.14;0.22) and 0.96(0.94;0.97) respectively. Therefore childhood HIV/TB mortality could be reduced if mothers are better catered for during pregnancy as this can reduce mother-to-child transmissions and contribute to improved birth weights. The INLA and SPDE approaches are computationally good alternatives in modelling large multilevel spatiotemporal GMRF data structures.  相似文献   
86.
This study was conducted to fit the diameter-height data of Quercusglaucain Jeju Island, South Korea to the four commonly used stem taper equations andto evaluate the performance of the four stem taper models using four statistical criteria: Fit index (FI), root mean square error (RMSE), bias (),and absolute mean difference (AMD). Results showed that the Kozak02stem taper equation provided the best FI(0.9847), RMSE(1.5745),(-0.0030 cm) and AMD (1.0990 cm) whileMax and Burkhart model had the poorest performance among the four stem taper models based on the four evaluation statistics (FI : 0.9793,RMSE : 1.8272, : 0.3040 cm and AMD : 1.3060 cm). These stem taper equations can serve as a useful tool for forest managers in estimating the diameter outside bark at any given height, merchantable stem volumes and total stem volumesof the standing trees of Quercusglaucain theGotjawal forests located in Mount Halla, Jeju Island, South Korea.  相似文献   
87.
随着物联网、云计算、移动互联网的迅猛发展,大数据(Big Data)吸引了越来越多的关注,正成为信息社会的重要财富,同时也给数据的处理与管理带来了巨大挑战.首先从大数据概念入手,阐述了大数据的来源、主要挑战、关键技术、大数据处理工具和应用实例等,并对比了大数据与云计算、物联网、移动互联网等技术之间关系,然后剖析了大数据核心技术、大数据企业解决方案,讨论了目前大数据应用实例,最后归纳总结了大数据发展趋势.旨在为了解大数据当前发展状况、关键技术以及科学地进行大数据分析与处理提供参考.  相似文献   
88.
基于GIS技术的重大危险源信息监控系统   总被引:11,自引:2,他引:9  
对重大危险源信息监控系统建设中的数据库设计和相关功能的实现技术进行了详细探讨,并对系统在功能实现上的作用进行了介绍。  相似文献   
89.
广西大厂矿田不但锡、锌、铅、锑等主要金属储量规模巨大,铟、锗、镉等稀散金属的经济价值也非常可观。本文系统收集整理了铜坑矿床资源勘查、开发过程中形成的1642个工程的编录资料,建立了三维空间数据库,对具有空间属性的Sn、Zn、Pb化学实验数据进行了统计分析。分析结果显示,相对92号矿体和细脉带矿体,91号矿体Sn、Zn品位高、富磁黄铁矿、主量金属相关性差,推测该矿体存在富含Sn、Zn的高温成矿流体叠加。岩浆期后热液型矿床随着远离含矿热液源头Zn/Pb值呈降低趋势,喷流沉积矿床随着距离喷口由近及远、沉积矿层由下往上,Zn/Pb值呈逐步增加趋势。铜坑矿床Zn/Pb空间分布规律是喷流沉积、岩浆热液叠加改造特征的复合,表明该矿床可能为喷流沉积-叠加改造复合成因。东岩墙(花岗斑岩脉)东西两侧随距离变远,Zn/Pb值呈近似对称性降低,推测东岩墙是成矿热液运移的通道。  相似文献   
90.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号