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71.
The densities of 36 water samples from the Huanghe River estuary and Bohai Bay were determinedby a magnetic float densimcter under three temperatures from 15℃ to 25℃.All the measured densities ofsamples were greater than that of the values calculated from the International Equation of State of Seawater.The differences between the measured and calculated densities increased with the decrease of salinities.The dif-ferences appeared exponentially correlated with[Ca~(2+)]/s,[Mg~(2+)]/s and[SO_4~(2-)]/s,and had"s"type curverelationship with the alkalinity in all salinity range.But in the salinity ranging from 25.72 to 31.57,therelationships were all linear.The density difference can be estimated from the equation △ρ(10~3kg·m~(-3))=(-2.79+236.5([Ca~(2+)]/s)/(-9.7464×10~(-3)+[Ca~(2+)]/s).It was the high alkalinity and[Ca~(2+)]/s that resulted in the measured densi-ties of seawaters being higher than the calculated densities in the Huanghe estuary and Bohai Bay.  相似文献   
72.
????CNES???????????????????λ???????д?????????????????о????????????????????????????????????????????????CNES??????????????????SuomiNet????????????????IGS??????????????????????????????????????????????????к???????  相似文献   
73.
????IGS???????GIM???????????????TEC??Total Electron Content?????????2007-2011???????й??????????17???M??≥6.0????????????????????PCA??Principal Component Analysis?? ???????????TEC??????????????????????????б???????????PCA??????????????????????????????????????????£???????????????TEC????????????????????????????0~5??  相似文献   
74.
Due to its rapid growth, the introduced mangrove species Sonneratia apetala from Bangladesh has been widely used in mangrove restoration in southeastern China since 1985. As an indigenous mangrove species in Hainan, China, Sonneratia caseolaris was also planted in Guangdong Province for afforestation purposes. Both species have developed well in their new habitats, but their ecophysiological differences with the native mangrove species have not been studied. In this study, leaf gas exchange, water and nitrogen use efficiencies of two Sonneratia species were compared with those of selected native mangrove species (Avicennia marina, Aegiceras corniculatum, Kandelia candel, and Excoecaria agallocha) in Hainan and Shenzhen. The introduced S. apetala maintained lower carbon assimilation rate (A) and photosynthetic nitrogen use efficiency (PNUE) than the indigenous S. caseolaris. In Shenzhen, the two introduced Sonneratia had comparable photosynthetic rates and water use efficiency (WUE) with the native mangrove species, except that PNUE in S. caseolaris was significantly higher than in the native mangrove species. The two Sonneratia species showed significant overlap in PNUE and long-term WUE. Photosynthetic parameters derived from leaf photosynthetic light–response curves and ACi curves also suggested lower carbon assimilation capacities for the introduced Sonneratia than for the native mangrove species in both study sites. The lower light compensation point (LCP) of two introduced Sonneratia in both study sites also indicated a better adaptation to a low light regime than the native mangrove species. The results of photosynthetic capacities indicated that the introduced mangrove species have little competitive advantage over local native mangrove species in their respective new habitats.  相似文献   
75.
GPU accelerated marine data visualization method   总被引:1,自引:0,他引:1  
The study of marine data visualization is of great value. Marine data, due to its large scale, random variation and multiresolution in nature, are hard to be visualized and analyzed. Nowadays, constructing an ocean model and visualizing model results have become some of the most important research topics of ‘Digital Ocean'. In this paper, a spherical ray casting method is developed to improve the traditional ray-casting algorithm and to make efficient use of GPUs. Aiming at the ocean current data, a 3D view-dependent line integral convolution method is used, in which the spatial frequency is adapted according to the distance from a camera. The study is based on a 3D virtual reality and visualization engine, namely the VV-Ocean. Some interactive operations are also provided to highlight the interesting structures and the characteristics of volumetric data. Finally, the marine data gathered in the East China Sea are displayed and analyzed. The results show that the method meets the requirements of real-time and interactive rendering.  相似文献   
76.
We report on the occurrence of Hα dimming associated with a sigmoid eruption in a quiet-sun region on 14 August 2001. The coronal sigmoid in soft X-ray images from the Yohkoh Soft X-ray Telescope was located over an Hα filament channel. Its eruption was accompanied by a flare of GOES X-ray class C2.3 and possibly associated with a halo coronal mass ejection (CME) observed with the Large Angle and Spectroscopic Coronagraphs (LASCO) on board the Solar and Heliospheric Observatory (SOHO). During the eruption, coronal bipolar double dimming took place at the regions with opposite magnetic polarities around the two sigmoid ends, but the underlying chromospheric channel did not show observable changes corresponding to the coronal eruption. Different from the erupting coronal sigmoid itself, however, the coronal dimming had a detectable chromosphere counterpart, i.e., Hα dimming. By regarding the sigmoid as a coronal sign for a flux rope, these observations are explained in the framework of the flux rope model of CMEs. The flux rope is possibly deeply rooted in the chromosphere, and the coronal and Hα dimming regions mark its evacuated feet, through which the material is possibly fed to the halo CME.  相似文献   
77.
论黄河上游多民族经济开发区资源开发战略   总被引:1,自引:0,他引:1  
本文在分析黄河上游多民族经济开发区资源特点的基础上,论证了经济区资源开发模式及开发战略,并就经济蛆内各区域非平衡开发及开发时序提出了一些见解。  相似文献   
78.

现代夏季风系统导致了南海西南部(越南岸外)上升流的发育,但浮游有孔虫对夏季上升流的响应如何尚缺乏实测资料,这不利于准确地利用有孔虫来重建古上升流的活动进而反演过去夏季风的强度变化。本研究利用2014年4月14日至11月1日布放于南海西南部夏季上升流区的时间序列沉积物捕获器材料,详细鉴定并定量统计了其所含浮游有孔虫类型。通过分析样品中浮游有孔虫各属种的通量和百分含量变化,结合区域气候环境资料,探讨南海西南部夏季上升流区浮游有孔虫对夏季风的响应,为古上升流与夏季风研究提供现代依据。研究结果表明初级生产力是控制上升流区浮游有孔虫通量变化的首要因素,喜营养种在上升流发育期增多而寡营养种含量下降。因此高表层生产力指示种,如Neogloboquadrina dutertrei可能是追溯南海西南部夏季上升流变化最可靠的指标。

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79.

黄昏爪兽(Hesperotherium)是我国早更新世代表物种之一,因发现标本稀少,其形态特征和灭绝时间是存疑的。重庆市万州区盐井沟大垭口地点发现了多件Hesperotherium化石,其中多数骨骼属首次发现,新材料增加了我们对该类动物的骨骼形态学的认识,其后肢骨骼在进化过程中较为保守,可能正是这种进化过程中的保守性导致其不能适应第四纪多变的气候环境,最终灭绝。同时通过对已知含Hesperotherium动物群的分析,认为Hesperotherium可以作为早更新世早-中期的代表物种,对应于邱占祥命名的NCMQ 1或欧洲的维拉方中-晚期。

  相似文献   
80.
沙丘粒度特征不仅能反映沙丘沙物质的来源与动力,也可以体现地形对风沙流运移的改变。对西藏朋曲流域不同地貌部位流动沙丘表层沉积物的粒度特征进行分析。结果表明:(1)朋曲流域流动沙丘表层沉积物粒度组分以中沙(46.51%)和细沙(40.52%)为主,粗沙(5.87%)与极细沙(5.87%)次之,黏土(0.37%)与粉沙(0.85%)含量最低。流动沙丘表层沉积物平均粒径1.41—2.32 Φ,分选系数0.45—0.79 Φ,偏度0.01—0.24,峰度0.98—1.80。(2)从河漫滩到河流阶地到山坡,流动沙丘粒度逐渐变小,频率分布曲线逐渐变高变窄,粒径越来越集中,沿主导风向自西南向东北概率累积曲线斜率逐渐增大,分选性逐渐变好。(3)河漫滩至河流高级阶地流动沙丘表层沉积物随海拔升高粒径变小,坡麓至坡顶随海拔升高粒径变大,分选却变好,表明山坡上沙丘与阶地上沙丘的沙物质来自于不同河段的河床或河漫滩。  相似文献   
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