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   333篇
  免费   18篇
  国内免费   23篇
测绘学   101篇
大气科学   48篇
地球物理   83篇
地质学   27篇
海洋学   61篇
天文学   7篇
综合类   26篇
自然地理   21篇
  2023年   2篇
  2022年   10篇
  2021年   10篇
  2020年   14篇
  2019年   18篇
  2018年   5篇
  2017年   16篇
  2016年   15篇
  2015年   8篇
  2014年   16篇
  2013年   29篇
  2012年   17篇
  2011年   15篇
  2010年   23篇
  2009年   16篇
  2008年   20篇
  2007年   26篇
  2006年   22篇
  2005年   14篇
  2004年   11篇
  2003年   17篇
  2002年   10篇
  2001年   3篇
  2000年   12篇
  1999年   6篇
  1998年   3篇
  1997年   4篇
  1996年   5篇
  1995年   2篇
  1994年   2篇
  1993年   1篇
  1990年   1篇
  1982年   1篇
排序方式: 共有374条查询结果,搜索用时 15 毫秒
291.
在含有运动地物的"凝视"卫星视频影像超分辨率重建问题中,针对由于运动估计不准确导致的重建后运动物体存在"格网"和"拖尾"等问题,提出了顾及运动估计误差的运动场景超分辨率重建方法。首先,在MAP模型框架下分析了基于L1范数和L2范数的保真项对于运动估计误差的稳健性,引入稳健的M-估计作为保真项,自适应的减少运动估计误差对重建结果的影响;然后,分析了稳健估计条件下Tikhonov、TV、BTV正则项的重建效果;最后,提出了基于稳健估计的双边滤波超分辨率重建方法,用SkyBox和吉林一号的卫星视频数据验证本文方法。试验证明,本文方法对含有运动目标的卫星视频影像具有较好的重建效果,重建后动态和静态地物细节都得到提升,归一化方差和梯度能量指标都优于其他方法。试验表明了本文方法的可行性。  相似文献   
292.
针对低空飞行器(飞艇)为平台获取的高清晰交通视频数据,通过对交通视频序列数据进行运动补偿与配准,提出了一个在复杂变化背景下基于帧差法的运动目标(车辆)快速检测与提取方法。实验结果验证了本方法的准确与可靠性。  相似文献   
293.
从物联网的根本目的出发,利用压缩方法和统计过程控制(SPC)技术研究了物联网中节点实时信息的精简和分析技术,并以计算机网络中的节点计算机的监视数据为例进行了实验分析,为物联网中节点数据的精简和分析提供了参考。  相似文献   
294.
数字视频加密技术发展现状及展望   总被引:8,自引:0,他引:8  
对视频加密所涉及到的基本原理和技术、存在的问题和一些重要的方法、当前研究热点及发展趋势等进行了全面介绍和综述;通过分析视频加密方法的特点,指出针对压缩视频数据信源特征而采用的选择性加密技术是未来的主要研究方向。  相似文献   
295.
介绍了利用视频技术检测激光束牛顿环中心的方法,为准直应用提供了参考。实验表明,快速Hough变换可以获取理想的检测结果。  相似文献   
296.
本文介绍了武汉市规划局在规划执法工作中提出利用3G无线视频监控技术和测绘近景摄影测量技术研制规划执法在线监控平台的思路,并具体介绍了平台研制的内容、实现的功能和应用的效果。实践证明,新技术和新成果的应用创新了规划执法工作方式,提高了执法效率。  相似文献   
297.
Fine scale disaster response and recovery data suitable for spatial analysis are still relatively rare. This is unfortunate as insight into spatial patterns of recovery could be invaluable in predicting the reestablishment of homes, streets and neighborhoods. The purpose of this paper is to show how fine scale geographic data can be collected in near real-time for the intermediate phase between response and recovery. These data will initially be used to assess the degree of damage (with relation to the Enhanced F scale) while also establishing a baseline for subsequent recovery monitoring. A spatial video system is used to collect data from the post-disaster landscape of Tuscaloosa which was hit by a large tornado in April 2011. This video, once processed, can be viewed within a Geographic Information System which combines street-level images with exact location. These data can be used to support ongoing recovery efforts, while also archiving a dataset suitable for the spatial analysis of the changing post-disaster landscape.  相似文献   
298.
《Urban geography》2012,33(10):1467-1484
ABSTRACT

In this paper, we investigate people’s perception of datafication and surveillance in Amsterdam Smart City. Based on a series of focus groups, we show how people understand new forms of hypervisbility, what strategies they use to navigate these experiences, and what the limitations of these strategies are. We show how people tried to discern between public and private sector actors, to differentiate who they trusted by building on the existing social contract. People also trusted the objectivity of data in relation to prior experiences of social contexts and discrimination. Lastly, we show how the experiences of some of the inhabitants in our study who were most vulnerable to hypervisibility highlight the limits to strategies based on the neutrality of data. By asking about perceived surveillance rather than emphasising actual practices of surveilling, we show differentiated contexts and strategies, providing empirical grounds to question the dominant technical framing of smart cities.  相似文献   
299.
多点双流模式在全运会天气会商中的应用   总被引:1,自引:0,他引:1  
滕迎建  于金源  马骏  黎亮 《气象科技》2010,38(Z1):118-120
针对早期电视会商系统存在的问题,分析了省级天气预报电视会商过程的应用需求,介绍了借助矩阵和中央控制系统,研究开发的适合电视会商需求的应用模式及其实现的原理和方法。通过对CRESTRON中央控制系统的控制指令进行编程,实现了同一会场内多点双流模式的电脑控制,并对模式实现的程序代码给出释义。经过检验,多点双流模式在省内天气会商、视频会议等应用中,操作简单、性能稳定。该应用模式已在十一届全运会气象保障平台上投入使用。  相似文献   
300.
Movies taken by witnesses of extreme flood events are increasingly available on video sharing websites. They potentially provide highly valuable information on flow velocities and hydraulic processes that can help improve the post‐flood determination of discharges in streams and flooded areas. We investigated the troubles and potential of applying the now mature large‐scale particle image velocimetry (LSPIV) technique to such flood movies that are recorded under non‐ideal conditions. Processing was performed using user‐friendly, free software only, such as Fudaa‐LSPIV. Typical issues related to the image processing and to the hydrological analysis are illustrated using a selected example of a pulsed flash‐flood flow filmed in a mountainous torrent. Simple corrections for lens distortion (fisheye) and limited incoherent camera movement (shake) were successfully applied, and the related errors were reduced to a few percents. Testing the different image resolution levels offered by YouTube showed that the difference in time‐averaged longitudinal velocity was less than 5% compared with full resolution. A limited number of GRPs, typically 10, is required, but they must be adequately distributed around the area of interest. The indirect determination of the water level is the main source of uncertainty in the results, usually much more than errors because of the longitudinal slope and waviness of the free‐surface of the flow. The image‐based method yielded direct discharge estimates of the base flow between pulses, of the pulse waves, and of the time‐averaged flow over a movie sequence including a series of five pulses. A comparison with traditional indirect determination methods showed that the critical‐depth method may produce significantly biassed results for such a fast, unsteady flow, while the slope‐area method seems to be more robust but would overestimate the time‐averaged flow rate if applied to the high‐water marks of a pulsed flow. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   
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