MicroRNAs identification and bioinformatics analysis in large yellow croaker Larimichthys crocea using an integrated comparative and ab initio approach     

房路京  肖世俊  韩兆方  王志勇 《中国海洋湖沼学报》2018,36(5):1707-1719

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规则池塘群的复杂直线模式识别     

刘呈熠  武芳  巩现勇  行瑞星  罗登瀚 《测绘学报》2020,49(2):256-266

针对现有面要素直线模式识别方法难以解决规则池塘中破碎区域的问题,提出了一种规则池塘群的复杂直线模式识别方法。首先,分析了规则池塘群的空间特征和认知特点,提出了“主次关系→并列关系→直线模式→复杂直线模式”的多层次认知顺序;其次,设计了主次关系池塘组、并列关系池塘组、直线模式池塘群的识别方法;最后,构建了复杂直线模式池塘群的识别模型。试验表明:本文方法能够消除破碎区域对规则池塘群直线模式提取的不利影响,有效提升复杂直线模式识别的质量。  相似文献   

长江经济带城市土地利用效率的影响因素及其空间溢出效应研究     

周晓艳  章芳  张苗苗 《测绘与空间地理信息》2020,(4):1-6

在人多地少的基本国情下,提高城市土地利用效率是促进区域可持续发展和建设生态文明的内在要求。本文在对2009-2016年长江经济带108个地级及以上城市土地利用效率的研究基础上,采用空间相关性研究方法分析了时空分布格局,通过构建空间杜宾模型(SDM)对其空间溢出效应进行分析。研究结果表明:1)2009-2016年长江经济带城市土地利用效率整体呈现稳定上升趋势;基本呈现以上海、南京、武汉等不同城市群中心城市向外逐步降低的“中心-外围”的分布格局。2)通过构建空间杜宾模型分析发现,经济发展水平、产业结构有显著为正的直接效应和溢出效应;土地市场化水平有显著为正的溢出效应;城市固定资产投资对城市土地利用效率具有正的直接效应和负的溢出效应;政府财政支出水平则对城市土地利用效率的直接效应和溢出效应均不明显。3)不同影响因素对经济带上中下游城市土地利用效率的空间效应存在一定差异性。  相似文献   

Discovery of Four New Clusters in the Cygnus Cloud     

秦松梅  李静  陈力  钟靖 《天文和天体物理学研究(英文版)》2021,(2)

We report the discovery of four new open clusters(named QC 1,QC 2,QC 3 and QC 4)in the direction of Cygnus Cloud and select their members based on five astrometric parameters(l,b,ω,μα*,μδ)of Gaia DR2.We also derive their astrophysical parameters for each new cluster.Structure parameters are generated by fitting the radial density distribution with a King’s profile.Using solar metallicity,we performed isochrone-fitting on their purified color-magnitude diagrams(CMDs)to derive the age of the clusters.The known cluster NGC 7062 in an adjacent area is chosen to verify our identification process.The estimated distance,reddening and age of NGC 7062 are in good agreement with the literature.  相似文献   

Classification of stellar spectra with SVM based on within-class scatter and between-class scatter     

Zhong-bao Liu  Fang-xiao Zhou  Zhen-tao Qin  Xue-gang Luo  Jing Zhang 《Astrophysics and Space Science》2018,363(7):140

Support Vector Machine (SVM) is a popular data mining technique, and it has been widely applied in astronomical tasks, especially in stellar spectra classification. Since SVM doesn’t take the data distribution into consideration, and therefore, its classification efficiencies can’t be greatly improved. Meanwhile, SVM ignores the internal information of the training dataset, such as the within-class structure and between-class structure. In view of this, we propose a new classification algorithm-SVM based on Within-Class Scatter and Between-Class Scatter (WBS-SVM) in this paper. WBS-SVM tries to find an optimal hyperplane to separate two classes. The difference is that it incorporates minimum within-class scatter and maximum between-class scatter in Linear Discriminant Analysis (LDA) into SVM. These two scatters represent the distributions of the training dataset, and the optimization of WBS-SVM ensures the samples in the same class are as close as possible and the samples in different classes are as far as possible. Experiments on the K-, F-, G-type stellar spectra from Sloan Digital Sky Survey (SDSS), Data Release 8 show that our proposed WBS-SVM can greatly improve the classification accuracies.  相似文献   

赤潮治理方法综述          下载免费PDF全文

韩锡锡  李琴  曹婧  于文涛  鞠莲 《海洋开发与管理》2018,35(4):76-80

文章综述目前赤潮治理的主要方法,其中物理法重点介绍机械搅动法、超声波法、吸附法和气浮法,化学法重点介绍无机药剂法、有机药剂法和胶体絮凝沉淀法,生物法主要介绍引入赤潮藻类生物天敌、微生物技术和化感技术,分析各自优势和不足,采用微生物技术和化感技术具有重要意义和发展前景。  相似文献   

紫外-可见分光光度法测定多花黄精多糖含量          下载免费PDF全文

曾婷  周芳  汤嫣然 《应用海洋学学报》2018,34(9):167-169

目的：测定湖南洪江国家黄精标准化基地多花黄精中的多糖含量，为多花黄精的进一步开发利用及药材质量标准研究奠定基础。方法：以葡萄糖为标准品，采用硫酸-蒽酮试剂显色，应用紫外-可见分光光度法测定多花黄精多糖含量。结果：葡萄糖在3.28～19.68μg/mL范围内线性良好（r=0.9992），多花黄精多糖平均含量为8.05%。结论：洪江种植基地的多花黄精品质优良，洪江是道地黄精药材种植理想基地。  相似文献   

Fast adsorption of microcystin-LR by Fe(III)-modified powdered activated carbon     

Dai  Guofei  Gan  Nanqin  Song  Lirong  Fang  Shaowen  Peng  Ningyan 《中国海洋湖沼学报》2018,36(4):1103-1111

Journal of Oceanology and Limnology - Microcystins (MCs) are cyclic hepatotoxic peptides produced by the bloom-forming cyanobacterium Microcystis and present a public health hazard to humans and...  相似文献   

Study of the flood control scheduling scheme for the Three Gorges Reservoir in a catastrophic flood          下载免费PDF全文

Shanghong Zhang  Zhu Jing  Wenda Li  Yujun Yi  Yong Zhao 《水文研究》2018,32(11):1625-1634

The Three Gorges Project is the world's largest water conservancy project. According to the design standards for the 1,000‐year flood, flood diversion areas in the Jingjiang reach of the Yangtze River must be utilized to ensure the safety of the Jingjiang area and the city of Wuhan. However, once these areas are used, the economic and life loss in these areas may be very great. Therefore, it is vital to reduce this loss by developing a scheme that reduces the use of the flood diversion areas through flood regulation by the Three Gorges Reservoir (TGR), under the premise of ensuring the safety of the Three Gorges Dam. For a 1,000‐year flood on the basis of a highly destructive flood in 1954, this paper evaluates scheduling schemes in which flood diversion areas are or are not used. The schemes are simulated based on 2.5‐m resolution reservoir topography and an optimized model of dynamic capacity flood regulation. The simulation results show the following. (a) In accord with the normal flood‐control regulation discharge, the maximum water level above the dam should be not more than 175 m, which ensures the safety of the dam and reservoir area. However, it is necessary to utilize the flood diversion areas within the Jingjiang area, and flood discharge can reach 2.81 billion m³. (b) In the case of relying on the TGR to impound floodwaters independently rather than using the flood diversion areas, the maximum water level above the dam reaches 177.35 m, which is less than the flood check level of 180.4 m to ensure the safety of the Three Gorges Dam. The average increase of the TGR water level in the Chongqing area is not more than 0.11 m, which indicates no significant effect on the upstream reservoir area. Comparing the various scheduling schemes, when the flood diversion areas are not used, it is believed that the TGR can execute safe flood control for a 1,000‐year flood, thereby greatly reducing flood damage.  相似文献   

珠江口淇澳岛滨海湿地沉积环境演化及其对人类活动的响应   总被引：1，自引：1，他引：0  

叶翔  李靖  王爱军 《海洋学报》2018,40(7):79-89

滨海湿地作为人类活动和全球变化反应最为敏感的区域，其沉积记录可以反映出周边地区环境变化及人类活动信息。珠江口淇澳岛滨海湿地钻孔分析结果表明，在中全新世期间淇澳岛附近海域为河口湾环境，在风化层以上开始出现淤积，但在4 200 a BP前后受极冷气候的影响，沉积物粗化；自2 500 a BP以来，沉积环境相对稳定，在小冰期期间略有变化。沉积速率计算结果显示:淇澳岛附近海域自中全新世高海面以来的平均沉积速率为0.29 cm/a，4 160~2 500 a BP、2 500 a BP-1488年、1488-1893年、1893-1986年、1990-2007年期间的平均沉积速率分别为:0.17 cm/a、0.23 cm/a、0.35 cm/a、1.37 cm/a和5.94 cm/a，沉积速率逐渐增大，反映了珠江三角洲演化过程中沉积相与沉积环境的变化；1986-1990年期间的海堤建造极大地扰动了该钻孔上部的沉积过程，在工程施工期间共沉积了厚度约112 cm的沉积层，而在海堤建成后，沉积速率也显著增大。沉积物总有机碳、总氮和C/N值的垂向分布表明，在4 160~2 500 a BP期间受海洋环境影响较大，沉积物中有机碳以海源为主，2 500 a BP以来沉积物中碳、氮含量明显增大，C/N也相应变大，有机碳主要来源于陆源输入，但在小冰期期间海源有机碳贡献略有所增大；近百年来由于受人类活动影响显著，陆源有机碳的贡献快速增加。  相似文献