全文获取类型
收费全文 | 617篇 |
免费 | 139篇 |
国内免费 | 172篇 |
专业分类
测绘学 | 61篇 |
大气科学 | 265篇 |
地球物理 | 207篇 |
地质学 | 261篇 |
海洋学 | 48篇 |
综合类 | 48篇 |
自然地理 | 38篇 |
出版年
2024年 | 17篇 |
2023年 | 27篇 |
2022年 | 35篇 |
2021年 | 54篇 |
2020年 | 47篇 |
2019年 | 52篇 |
2018年 | 27篇 |
2017年 | 40篇 |
2016年 | 32篇 |
2015年 | 43篇 |
2014年 | 72篇 |
2013年 | 51篇 |
2012年 | 54篇 |
2011年 | 58篇 |
2010年 | 35篇 |
2009年 | 40篇 |
2008年 | 31篇 |
2007年 | 45篇 |
2006年 | 35篇 |
2005年 | 47篇 |
2004年 | 22篇 |
2003年 | 12篇 |
2002年 | 7篇 |
2001年 | 7篇 |
2000年 | 4篇 |
1999年 | 3篇 |
1998年 | 4篇 |
1997年 | 3篇 |
1996年 | 2篇 |
1995年 | 6篇 |
1994年 | 1篇 |
1993年 | 3篇 |
1992年 | 3篇 |
1991年 | 4篇 |
1990年 | 4篇 |
1985年 | 1篇 |
排序方式: 共有928条查询结果,搜索用时 0 毫秒
141.
基于地磁与红外双模探测的海洋浮标预警系统设计 总被引:1,自引:0,他引:1
设计了一种基于地磁检测与红外感应相结合、可对浮标周围异常目标进行探测和预警的控制系统。系统采用芯片级的微型磁感线圈,以及高集成度、低功耗的数据采集与总线技术,通过探测船体磁性对地磁场的扰动,监测船舶对浮标的靠近;采用芯片级的热释电红外传感器,通过探测人体红外辐射,监测浮标在正常工作期间未知人员的入侵。系统的预警采用声光报警和图像远程传输相结合的方式,现场采集的图像数据经过压缩编码后通过无线数传电台发送至远程岸基监测站,实现海洋浮标的远程预警与现场取证功能。 相似文献
142.
143.
Pierre Javelle Julie Demargne Dimitri Defrance Jean Pansu Patrick Arnaud 《水文科学杂志》2014,59(7):1390-1402
AbstractThis article presents a comparison between real-time discharges calculated by a flash-flood warning system and post-event flood peak estimates. The studied event occurred on 15 and 16 June 2010 at the Argens catchment located in the south of France. Real-time flood warnings were provided by the AIGA (Adaptation d’Information Géographique pour l’Alerte en Crue) warning system, which is based on a simple distributed hydrological model run at a 1-km2 resolution using radar rainfall information. The timing of the warnings (updated every 15 min) was compared to the observed flood impacts. Furthermore, “consolidated” flood peaks estimated by an intensive post-event survey were used to evaluate the AIGA-estimated peak discharges. The results indicated that the AIGA warnings clearly identified the most affected areas. However, the effective lead-time of the event detection was short, especially for fast-response catchments, because the current method does not take into account any rainfall forecast. The flood peak analysis showed a relatively good correspondence between AIGA- and field-estimated peak values, although some differences were due to the rainfall underestimation by the radar and rainfall–runoff model limitations.
Editor Z.W. Kundzewicz; Guest editor R.J. MooreCitation Javelle, P., Demargne, J., Defrance, D., Pansu, J. and Arnaud, P., 2014. Evaluating flash-flood warnings at ungauged locations using post-event surveys: a case study with the AIGA warning system. Hydrological Sciences Journal, 59 (7), 1390–1402. http://dx.doi.org/10.1080/02626667.2014.923970 相似文献
144.
145.
对滇西实验场1992年以来地下流体前兆观测资料进行分析研究,选取应震效果通过R信度检验(对应MS≥5.0级地震)的8条单项前兆指标。综合考虑单项前兆指标虚报率和漏报率对指标信度的影响,对单项前兆指标利用数学模型进行综合处理,减少了虚报和漏报的次数,预测效果明显提高。利用分级预警模式分别建立了中期(T≤6个月)和短临(T≤3个月)预测模型。综合预测方案还提供了地点判定原则和震级估算原则。最终提供地震短临预测三要素。运用本综合预测方案对2011年腾冲5级双震、2013年洱源5级双震和德钦两次5级地震作用了较为成功的短临预测。 相似文献
146.
Bimal Kanti Paul 《Natural Hazards》2009,50(2):289-304
Cyclone Sidr, a Category IV storm, struck the southwestern coast of Bangladesh on November 15, 2007 killing 3,406 people.
Despite a similar magnitude, Sidr claimed far fewer lives than Cyclone Gorky, also a Category IV storm, which struck Bangladesh
in 1991 causing an estimated 140,000 fatalities. The relatively low number of deaths experienced with Sidr is widely considered
the result of Bangladesh government’s efforts to provide timely cyclone forecasting and early warnings, and successful evacuation
of coastal residents from the projected path of Cyclone Sidr. Using information collected from both primary and secondary
sources, this study identified several other reasons for the unexpectedly lower mortality associated with Cyclone Sidr relative
to Cyclone Gorky. Fewer casualties may be attributed to a number of physical characteristics of Cyclone Sidr, such as duration
of the storm and storm surge, landfall time and site, varied coastal ecology, and coastal embankment. This article recommends
improvements to the cyclone warning systems, establishment of more public cyclone shelters, and implementation of an education
campaign in coastal areas to increase the utilization of public shelters for future cyclone events. 相似文献
147.
Abstract Canada has increased the number of tsunami warning stations on the Pacific Coast from two to three. The last gauge was installed at the north end of Vancouver Island, thereby filling a large gap previously existing and providing full coverage along the coast. The record of gauges at two of the three locations is accessible either by telephone or by means of meteor burst communication, alleviating the difficulties experienced during the tsunami threat of May 6, 1986, when telephone communications were disrupted by heavy use. The gauge at Langara Island will be relocated in a more accessible and also a more tsunami‐responsive location at Rennell Sound in the Queen Charlotte Islands. All tsunami gauges also serve as tide gauges, recording the water level every 15 min. In the event of a tsunami, the recording interval can be altered to every 60 s. Suggestions have been made that Canada attempt deep‐sea recording of tsunamis off its Pacific Coast. Although this would be of great scientific value, no such program is contemplated at this time. 相似文献
148.
通过引入地质灾害潜势度,突发地质灾害气象预警统计模型解决了雨量判据法不能明确表达地质环境条件的问题,在此基础上,提出了潜势度计算、大气降雨变量设计、预警方程优化3方面的改进方法。为提高潜势度计算的准确性,增加了基于卡方检验的地质环境因子独立性判别步骤;对地质环境因子确信程度初始值和权值计算中确信程度变化量初始值设置进行了规定;并将预警模型中累计雨量修正为更为合理的有效累计雨量。在现有的预警方程的基础上提出了基于联合概率分析的预警方程,避免了其与基本地质认识和物理规律存在一定距离、方程系数的意义不明确的局限。以2009年7月2日发布的24 h雨量预报为例,计算结果表明:虽然预报区域面积从101 008 km2减小到27 553 km2,但是地质灾害点落入预报区的比例从44%增加到62%。这说明通过改进的预警模型理论上更加严密,空间准确率有所提高,空报率有所下降。 相似文献
149.
This paper evaluates different characteristics for earthquake early warning.The scaling relationships between magnitude,epicenter distance and calculated parameters are derived from earthquake event data from USGS.The standard STA/LTA method is modified by adding two new parameters to eliminate the effects of the spike-type noise and small pulsetype noise ahead of the onset of the P-wave.After the detection of the P-wave,the algorithm extracts 12 kinds of parameters from the first 3 seconds of the P-wave.Then stepwise regression analysis of these parameters is performed to estimate the epicentral distance and magnitude.Six different parameters are selected to estimate the epicentral distance,and the median error for all 419 estimates is 16.5 km.Four parameters are optimally combined to estimate the magnitude,and the mean error for all events is 0.0 magnitude units,with a standard deviation of 0.5.Finally,based on the estimation results,additional work is proposed to improve the accuracy of the results. 相似文献
150.
利用GPS对构筑物进行动态变形监测,获取构筑物的动态变形序列,通过卡尔曼滤波处理变形时间序列,从而削弱相关噪声的影响,提取真实的变形信号,并通过FFT处理变形信号,验证其滤波效果.在分析累积和算法的前提下,构建构筑物预警模型,分析了平均运行长度及预警阈值等相关参数的选取原则.经实测数据分析,模型能有效检测到变形发生时刻,该方法能够提高GPS进行动态变形预警的可靠性,特别是为微小变形提供一定研究指导意义. 相似文献