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1.
海洋高光谱遥感研究进展   总被引:14,自引:0,他引:14       下载免费PDF全文
海洋遥感是20世纪后期海洋科学取得重大进展的关键技术之一。所谓海洋遥感就是利用电磁波与大气和海洋的相互作用原理 ,从各种平台观测和研究海洋的一项技术[1]。海洋遥感具有观测周期短 ,时间频率高的优势 ,可实现大面积、实时、同步、连续而密集的海洋探测 ,较好地适应了海洋各种现象和过程的特点。随着光电子技术和计算机技术水平的提高 ,遥感传感器的技术性能不断提高。高光谱遥感(Hyperspectralremotesensing)是当前遥感技术的前沿领域 ,它是指利用很多很窄的电磁波波段从感兴趣的物体获得有关数据 […  相似文献   
2.
The possible global sea level rise and its magnitude in the next century induced by the doubling of atmospheric carbon dioxide concentration are briefly discussed. The rates of crustal sinking, ground surface aggradation, and sediment compaction which might give rise to the regional characteristics of relative sea level (RSL) changes, are studied in detail. Attention is focused on the following problems that are closely associated to the sea level rise in the next century: 1) the flood susceptibility of the low-lying East Qhina plains in the next century and its historical evidences, 2) the frequency of disastrous floods and storm surges, 3) the aggradational rate and the potential danger to the dikes along die Changjiang River's lower reaches and 4) the salt water intrusion and the water quality in the Changjiang River estuary. The study shows that the adverse impacts would be very great even if only the lower estimate of sea-level rise in the next century is considered. Therefore, comprehensive resear  相似文献   
3.
南水北调对长江口粗颗粒悬沙来量的影响   总被引:7,自引:2,他引:7       下载免费PDF全文
探索了长江南水北调占总径流量10%情况下对长江粗颗粒悬沙(≥0.05mm)入海数量变化的可能影响。研究表明:南水北调对入海细颗粒泥沙的影响主要为南沙北调,但数量较小,在1%左右,而对粗颗粒悬沙的影响主要表现在入海流量减少导致的水体挟沙能力的降低。通过建立大通站典型枯水年(1978),平水年(1987)及洪水年(1983)月平均流量与月平均床沙质输沙率相关曲线,估算出各典型年在典型流量23000m3/s,30000m3/s与40000m3/s水平下调水流量3000m3/s时导致的入海床沙质输沙率的变化。结果表明,输沙率的相对变化在-39%至-24%之间,且在较高的流量水平下,输沙率相对变化较小,但绝对变化增大,经大通入海的床沙质数量每年约减少2350~4700万t.  相似文献   
4.
长江河口悬浮颗粒物研究   总被引:31,自引:5,他引:26  
1994年11月、1996年9月和1997年1月使用FACScan流式细胞仪技术等分析观测手段对长江河口悬浮体进行了研究。结果表明,长江河口悬浮体中,具有有机性的颗粒数占总颗粒数的60% ̄70%;在颗粒粒径分布上,粗颗粒物质(〉8μm)主要为有机物质(生物残体、小型藻类、矿物-有机物集合体),细颗粒物质(〈8μm)主要为粘土矿物、有有机物附着和具有有机裹层的粘呈集合体;有机性颗粒物质含量随盐度变化  相似文献   
5.
Based on the one-dimensional salinity transport equation with constant diffusion coefficient, and separated water flow velocity into runoff and tidal current with the single-frequency in an idealized estuary, the simplest unsteady analytical so- lution of salinity intrusion is deduced and the estimation formula of diffusion coefficient is obtained in this paper. The unsteady solution indicates that salinity process in estuaries results from the interaction of runoff and tidal current, and its amplitude is in direct proportion to the product of the velocity of runoff water and the amplitude of tidal flow velocity and in inverse proportion to the diffusion coefficient and the tidal angular frequency, and its phase lag tidal flow with 7/2 which reveals the basic features of the maximum salinity appearing after flood slack and the minimum salinity appearing before ebb slack under the effect of runoff (the advance or lag time is relative to the magnitude of runoff and tidal flow). According to the measured flow velocity and salinity data, the salinity diffusion coefficient could be estimated. Finally, with the field data of observing sites on the deepwater navigation channel of the Yangtze Estuary, the diffusion coefficient is calculated and a comparative analysis of simulated and measured of salinity process is made. The results show that the solution can comprehensively reflects the basic characteristics and processes of salinity intrusion under the interaction of runoff and tidal flow in estuaries. The solution is not only suitable for theoretical research, but also convenient for estimating reasonable physical parameters and giving the initial condition in the salinity intrusion numerical simulation.  相似文献   
6.
长江大通-河口段枯季的径流量变化   总被引:10,自引:2,他引:10  
张二凤  陈西庆 《地理学报》2003,58(2):231-238
通过实地调查和收集长江下游1950-2000年水文、水利工程资料,建立了长江大通以下枯季径流量变化地理信息系统,分析了影响长江大通水文站以下径流量变化的水文过程,探索了这一区间枯季径流量变化的成因与过程。调查研究表明,截止2000年大通以下各类抽引水工程的总数已达64个,抽引水能力达到了4626m^3/s(潮周期内平均轴引水流量)。实际抽引水量呈现很大的年、季波动,这与本区气候干旱情况、农作物生长期、跨流域调水量等多种因素有关。研究表明:大通-河口段沿江两岸大量的抽引水已成为影响长江大通以下枯季入海流量变化的最重要的因素。本文在过去实际抽引江水资料的基础上,估算了过去不同水文、气候背景下长江大通以下枯季径流量的变化幅度及其对入海流量的影响,并利用实际数据进行了验证。在此基础上,探讨了未来长江大通以下枯季的径流量变化趋势。  相似文献   
7.
河流环境流量法研究进展   总被引:4,自引:0,他引:4       下载免费PDF全文
回顾了20世纪80年代以来,国内外在河流环境流量法方面的研究进展,包括研究现状、方法类别及发展趋势。在国外,从考虑单一水文要素的水文学法,到考虑多学科交叉的整体分析法,逐步建立起一套完整的方法研究体系,今后发展趋势是通过国际间的合作研究,开发满足不同国家国情和水情特点的综合环境流量法。在国内,研究尚处于起步阶段,大多停留在定性分析水平上,定量分析,计算比较简单,主要采用的是水文学法,如Tennant法、7Q10法等,今后的研究方向一方面要加强基础研究工作,另一方面要根据本国(或流域、或地区)特点开发出适合于国情和水情的环境流量法,研究地区也应从干旱半干旱的北方地区转移到水资源较为丰富的南方地区。  相似文献   
8.
陈西庆 《地理学报》1998,53(4):323-333
本文对Bruun法则 应用的前提-海岸剖面的基本问题进行了深入探讨,提出长江三角洲海岸不发育经典理论中砂质海岸那种较为严格的均衡剖面。  相似文献   
9.
杨达源 《第四纪研究》2009,29(6):1170-1171
编辑按 杨怀仁先生是我国著名的地貌学与第四纪地质学家,在地貌与第四纪科学研究、教学和人才培养方面做出了杰出贡献。前不久,杨先生因病逝世。《第四纪研究》特刊载南京大学地理与海洋科学学院杨达源教授等撰写的纪念短文,以表达学界对先生的缅怀之情。  相似文献   
10.
Based on hydrometric data and extensive investigations on water-extracting projects, this paper presents a preliminary study on water discharge changes between Datong and Xuliujing during dry season. The natural hydrological processes and human factors that influence the water discharge are analyzed with the help of GIS method. The investigations indicate that the water-extracting projects downstream from Datong to Xuliujing had amounted to 64 in number by the end of 2000,with a water-extracting capacity up to 4,626 m3/s averaged in a tidal cycle. The water extraction from the Changjiang River has become the most important factor influencing the water discharge downstream Datong during dry season. The potential magnitude in water discharge changes are estimated based on historical records of water extraction and a water balance model. The computational results were calibrated with the actual data. The future trend in changes of water discharge into the sea during dry season was discussed by taking into consideration of newly built hydro-engineering projects. The water extraction downstream Datong in dry season before 2000 had a great influence on discharges into the sea in the extremely dry year like 1978-1979. It produced a net decrease of more than 490 m^3/s in monthly mean discharges from the Changjiang into the sea. It is expected that the water extraction will continually increase in the coming decades, especially in dry years, when the net decrease in monthly mean water discharge will increase to more than 1000 m^3/s and will give a far-reaching effect on the changes of water discharge from the Changjiang into the sea.  相似文献   
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