排序方式： 共有17条查询结果，搜索用时 15 毫秒
11.
Changes in fish diversity and community structure in the central and southern Yellow Sea from 2003 to 2015 总被引：1，自引：0，他引：1
The central and southern Yellow Sea is an important overwintering ground for many fish species in the Bohai Sea and Yellow Sea. For better understanding the status of the fish community after years of heavy exploitation, variations in fish community structure and diversity were analyzed using data from bottom trawls during 2003–2015. Five fish assemblage indices all showed fluctuations without clear trends from 2003 to 2015, yet there were strong positive and significant correlations(P 0.05) among them. The top-five dominant species accounted for a high weight percentage(49.7%–82.1%) in the annual fish catch. Multivariate analysis showed that two year groups could be pooled for the fish community: Group Ⅰ consisted of the years 2006, 2007, 2008 and 2015, while Group Ⅱ consisted of the years 2003, 2004, 2005, 2009, 2010 and 2014; the groups aggregated with 63.71% similarity, indicating a high level of similarity among all years. The multivariate dispersion values were 1.455 and 0.818 for Groups Ⅰ and Ⅱ, respectively, indicating greater variances in fish assemblage structure in Group Ⅰ than that in Group Ⅱ. Similarity of percentage analysis demonstrated that the average similarities for Group Ⅰ and Group Ⅱ were 71.58% and 67.51%, respectively. Size-spectra analysis revealed no consistent trend in the intercept and slope( P 0.05); there were also no significant differences between the slope of the size-spectra and fishing ef fort. The catch per unit ef fort and mean individual weight analyses of the whole fish assemblage both showed a significantly decreasing trend over time. Overall, the results showed that the fish community structure in the central and southern Yellow Sea was relatively stable from 2003 to 2015 and the study could be used as a reference for supporting ecosystem-based fishery management. 相似文献
12.
我国开发利用海洋矿产资源所面临的国际问题及对策 总被引：1，自引：0，他引：1
论述了我国海洋矿产资源的拥有状况及开发现状,以及面临的国际问题,提出了相应的对策和解决途径,即增强全国人民的"海洋国土"意识,发展与拥有周边海洋邻国的睦邻友好关系,旗帜鲜明地捍卫国家的海洋权益和海洋领土完整.为国家制定切实可行的海洋资源开发计划提供参考. 相似文献
13.
14.
15.
对司马迁《报任安书》“彼观其意”之“彼”，几家主要注释都把它作代词看待，在所代内容上有分歧，有的认为代“李陵”，有的认为代作者，有的认为代“匈奴”；在断句上意见也不相同，这些观点均有不足之处。在对这些观点分析的基础上，提出“彼”通“夫”，是句首语气词。 相似文献
16.
保温保压取样,作为开展海域天然气水合物勘查工作的关键技术方法,是采获水合物原位样品的核心技术手段。本文对国内外海域天然气水合物保温保压取样钻具的相关资料进行了汇总梳理,并从工作原理、结构特点和试验应用等方面对国内保温保压取样钻具的研究与应用进展进行了分析与总结。通过采用不同的工作原理,国内保温保压取样钻具已能够在软-中硬-硬地层中进行取样,在工程应用中的保压成功率、岩心收获率等性能指标能够满足取样需求,有效推进了天然气水合物勘查评价自主化实施进程。 相似文献
17.