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941.
The status of fishery stocks in the coastal waters of China is far from ideal, mainly due to climate change and the impacts of human activities (e.g., pollution and overfishing). Thus, the restoration and protection of fishery resources have become critical and complex. The stability and balanced structure of the fish community is a basic foundation for the protection of fishery resources. Based on data collected from bottom trawls by the R/V Beidou in continental shelf of the East China Sea in November 2006 and February 2007, changes in the composition and diversity of fish species and functional groups were analyzed. The research area was divided into offshore waters and inshore waters by the two-way indicator species analysis (TWIA). The results showed that the dominant species were different between offshore waters and inshore waters and also varied with the survey time. The most abundant family was Sciaenidae and Teraponidae in November 2006, Sciaenidae, Engraulidae and Triglidae were most abundant in February 2007. The species belonged mainly to mobile piscivores (G6), benthivores/piscivores (G4), benthivores (G3) and planktivores (G1), and the dominant species in November 2006 were commercial species (e.g. Larimichthys polyactis and Trichiurus japonicus), but small-sized species were dominant in February 2007 (e.g., Harpadon nehereus, Benthosema pterotum, Champsodon capensis, and Acropoma japonicum). The species diversity showed a similar trend as the functional group diversity. Stations with higher diversity were mainly distributed in inshore waters in February 2007, whereas higher diversity was found in offshore waters in November 2006. The highest biomass and species number were found in G6 group, followed by the G4, G5 and G1 groups. The distribution of the number of individuals of each functional group showed the opposite trend as that of the biomass distribution. In addition, the size spectra were mainly concentrated around 3–29 cm, and the individual number of fish species gradually decreased with the increase in body size, but the relative biomass showed a moderate fluctuation in each size class. These changes showed that species with faster growth rate and earlier maturity age became dominant in continental shelf of the East China Sea. So the variations in biological characteristics of fish should be fully considered in maintaining sustainable utilization of fishery resource.  相似文献   
942.
基于1961—2013年中国台站的均一化气温数据、NOAA月平均海温资料和CMIP5气候模式数据,利用气候统计手段,定量分析太平洋年代际振荡(PDO)对中国冬季最低气温年代际变化的贡献。结果表明:PDO的年代际序列与年代际滤波后的最低气温场在全国大部分地区呈显著正相关,即PDO负位相时中国冬季最低气温偏低,反之偏高。2006年后中国冬季最低气温变暖减缓,造成这一现象的主要原因是自然变率起到的降温作用,而自然变率又主要由PDO起主导作用,约占自然变率贡献的40%左右。PDO对温度的贡献呈现出明显的年代际变化,在变暖减缓期对升温有明显的负贡献,且负贡献逐渐增大至超过50%。  相似文献   
943.
利用常规观测资料、加密自动站资料,对2014年萍乡市一次区域性暴雨过程进行了分析。结果表明:低层西南急流,湿舌以及暖脊均伸向萍乡市,表明有明显的水汽输入、热力不稳定层结和湿斜压性,且萍乡市处于低涡暖切变南侧的强辐合区,是一次较易把握的暴雨过程,但萍乡市仅中部和北部的局部出现暴雨。利用ECMWF高分辨率资料计算了动力因子,对暴雨落区做进一步分析发现:1)广义位温水平梯度高值区和湿热力平流参数正、负中心交界面存在明显的热力不连续面、水平锋生和湿斜压性,与萍乡市中部和北部的降水有较好的对应关系。2)热力垂直螺旋度、水汽垂直螺旋度和热力位涡波作用密度的正、负中心交界面存在充沛的热量和水汽的输送、较强的垂直风切变、涡度矢量的扰动以及热量散度的扰动,对萍乡市中北部的强降水中心有较好的指示作用。  相似文献   
944.
In this study, the hierarchical clustering technique, called Ward method, was applied for grouping common features of air temperature series, precipitation total and relative humidity series of 244 stations in Turkey. Results of clustering exhibited the impact of physical geographical features of Turkey, such as topography, orography, land–sea distribution and the high Anatolian peninsula on the geographical variability. Based on the monthly series of nine climatological observations recorded for the period of 1970–2010, 12 and 14 clusters of climate zones are determined. However, from the comparative analyses, it is decided that 14 clusters represent the climate of Turkey more realistically. These clusters are named as (1) Dry Summer Subtropical Semihumid Coastal Aegean Region; (2) Dry-Subhumid Mid-Western Anatolia Region; (3 and 4) Dry Summer Subtropical Humid Coastal Mediterranean region [(3) West coast Mediterranean and (4) Eastern Mediterranean sub-regions]; (5) Semihumid Eastern Marmara Transition Sub-region; (6) Dry Summer Subtropical Semihumid/Semiarid Continental Mediterranean region; (7) Semihumid Cold Continental Eastern Anatolia region; (8) Dry-subhumid/Semiarid Continental Central Anatolia Region; (9 and 10) Mid-latitude Humid Temperate Coastal Black Sea Region [(9) West Coast Black Sea and (10) East Coast Black Sea sub-regions]; (11) Semihumid Western Marmara Transition Sub-region; (12) Semihumid Continental Central to Eastern Anatolia Sub-region; (13) Rainy Summer Semihumid Cold Continental Northeastern Anatolia Sub-region; and (14) Semihumid Continental Mediterranean to Eastern Anatolia Transition Sub-region. We believe that this study can be considered as a reference for the other climate-related researches of Turkey, and can be useful for the detection of Turkish climate regions, which are obtained by a long-term time course dataset having many meteorological variables.  相似文献   
945.
城市宜居环境综合评价本质上是城市内部包括物质空间、社会文化空间等众多要素之间的结构关系研究。城市系统结构可以分为不同的亚系统,亚系统之间的关系可以用数量方法确定。以中国老年人宜居城市评价指标体系为例,介绍和比较了各种宜居环境评价指标体系指标赋权的方法,应用关联矩阵法确定老年人城市宜居环境各亚系统之间,以及亚系统内部各个指标的重要性。旨在说明关联矩阵法在确定城市结构中各亚系统关联度上具有合理、简便的特点,尤其是具有将客观性与主观性评价相结合的优势。  相似文献   
946.
中国重大科技计划中人文-经济地理学研究进展   总被引:1,自引:0,他引:1  
为跟踪世界科技的最新进展,解决中国快速发展过程中所面临的关键性和突出性重大问题,中国政府开展了一系列重大科技专项计划,如科技支撑计划等。气候变化、地表过程、土地利用、自然灾害是近年来人文一经济地理学者参与最广、研究最深的领域,在地表过程的人文驱动机制、资源环境承载能力评价等方面取得了重大进展和突破,为政府编制规划、开展环境外交等提供了科学依据。本文分析了上述研究计划的基本概貌,以及人文一经济地理学者在其中承担的主要任务。从个人终端消费导向的碳足迹研究、人文地理过程的系统动力学研究、土地利用重点问题咨询与决策、灾区资源环境承载能力评价等方面总结了人文一经济地理学在其中做出的主要贡献和社会影响。  相似文献   
947.
以Zn(Ac)2.2H2O和NaOH为原料,十六烷基三甲基溴化胺(CTAB)为表面活性剂,采用水热法合成了不同形态的氧化锌。利用X-ray粉末衍射仪(Powder X-ray Diffractometer,XRD)、红外光谱仪(Infra-red Spectrometer,IR)、场发射扫描电镜表征所合成材料的结构和形貌。用紫外可见光度计、荧光光度计研究了氧化锌的光学性能。为了评估氧化锌的催化性能,进行了纳米氧化锌对乙酸和正丁醇合成乙酸正丁酯的催化实验。实验结果表明,纳米氧化锌对酯化反应具有很好的催化作用,催化活性与颗粒大小有一定的关系。  相似文献   
948.
Building vulnerability evaluation in landslide deformation phase   总被引:1,自引:0,他引:1  
Building vulnerability evaluation is important in the risk assessment on earthquake and flood hazards. But for landslide hazard, it is also a very important part for the people in buildings. Most discussions or researches about building vulnerability are for landslide failure, few for landslide in deformation phase. For this objective, this paper discussed about building vulnerability evaluation using Zhaoshuling landslide as an example Zhaoshuling landslide named located in the Three Gorges Reservoir Area, China. After a field survey on the geological condition of landslide, detailed field investigation on the buildings’ location and structure is carried out. To get landslide surface deformation, numerical simulation method is used under the combining condition of water fluctuation and rainfall. Then building deformation and probable damage degree is analyzed according to landslide surface deformation and the relative theory in mining. Based on the national standard building damage classification system, the vulnerability of all the buildings on the landslide is semi-quantitatively evaluated.  相似文献   
949.
2016年初萍乡地区两次降雪过程对比分析   总被引:1,自引:0,他引:1       下载免费PDF全文
利用常规气象观测资料对萍乡地区2016年1月和2月两次相临的降雪过程进行对比分析,结果表明,1月过程的冷空气强度、动力条件、水汽条件及不稳定条件均优于2月过程,但1月过程仅出现零星小雪,2月过程却出现了大雪。采用ECWMF高分辨率资料和GPS/MET可降水量资料对两次过程进行更深入分析发现,1月过程的水汽条件、上升运动条件以及对称不稳定条件有明显的衰减,而2月过程中的水汽条件、上升运动条件以及对称不稳定条件都有所增强,且持续时间较长。  相似文献   
950.
INTRODUCTIONAtpresentgiantfreshwaterprawn (Macrobrachiumrosenbergii) ,Chineseshrimp (Penaeuschinensis)andgianttigerprawn (P .monodon)arethemainshrimpsforcultureinChina.Asweknow ,feedstuffcostisamajorexpenseiteminculturepractice.Overfeedingwillnotonlywastefee…  相似文献   
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