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31.
The taxonomy of Coilia has been extensively studied in China, and yet phylogenetic relationships among component taxa remain controversial. We used
a PCR-based fingerprinting technique, amplified fragment length polymorphism (AFLP) to characterize and identify all four
species of Coilia in China. We examined the genetic relationships of the four species of Coilia and a subspecies of Coilia nasus with AFLP. A total of 180 AFLP loci were generated from six primer combinations, of which 76.11% were polymorphic. The mean
genetic distance between pairs of taxa ranged from 0.047 to 0.596. The neighbor-joining tree and UPGMA dendrogram resolved
the investigated species into three separate lineages: (1) C. mystus, (2) C. grayii and (3) C. brachygnathus, C. nasus, and C. nasus taihuensis. Phylogenetic analysis of the AFLP data is inconsistent with current morphological taxonomic systems. The AFLP data indicated
a close relationship among C. brachygnathus, C. nasus taihuensis, and C. nasus. Therefore, the two species described under Coilia (C. brachygnathus and C. nasus taihuensis) are treated as synonyms of C. nasus. 相似文献
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The HY-2A satellite is the first ocean dynamic environment monitoring satellite of China. Centimeter-level radial accuracy is a fundamental requirement for its scientific research and applications. To achieve this goal, we designed the strategies of precise orbit determination (POD) in detail. To achieve the relative optimal orbit for HY-2A, we carried out POD using DORIS-only, SLR-only, and DORIS + SLR tracking data, respectively. POD tests demonstrated that the consistency level of DORIS-only and SLR-only orbits with respect to the CNES orbits were about 1.81 cm and 3.34 cm in radial direction in the dynamic sense, respectively. We designed 6 cases of different weight combinations for DORIS and SLR data, and found that the optimal relative weight group was 0.2 mm/s for DORIS and 15.0 cm for SLR, and RMS of orbit differences with respect to the CNES orbits in radial direction and three-dimensional (3D) were 1.37 cm and 5.87 cm, respectively. These tests indicated that the relative radial and 3D accuracies computed using DORIS + SLR data with the optimal relative weight set were obviously higher than those computed using DORIS-only and SLR-only data, and satisfied the requirement of designed precision. The POD for HY-2A will provide the invaluable experience for the following HY-2B, HY-2C, and HY-2D satellites. 相似文献
33.
Inter-simple sequence repeat (ISSR) markers were used to determine the genetic variation and genetic differentiation of cultured and wild populations of Trachidermus fasciatus, an endangered catadromous fish species in China. Six selected primers were used to amplify DNA samples from 85 individuals, and 353 loci were detected. Relatively low genetic diversity was detected in the cultured population (the percentage of polymorphic loci PPL = 73.80%, Nei’s gene diversity h = 0.178 2, Shannon information index ... 相似文献
34.
金陵山一带发现的晚石炭世纺锤虫类计有8属15种,其中新种3个,未定种3个,可称为Sphaeroschwagerina-Pseudofusulina动物群,与新疆柯坪地区康克林组Pseudoschwagerina带的下两个亚带对比。 相似文献
35.
Journal of Oceanology and Limnology - Studies of range-wide populations can contribute to the comprehension of the relative roles of historical events and contemporary factors that influence... 相似文献
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针对基线解算质量的提高,除了在野外观测时必须按要求采取相应措施减少各种不利因素的影响外,还需要在必要时通过一定的手段来改进基线向量成果,提高网平差精度。通过南方测绘GNSS数据处理软件对不同卫星高度截止角、历元间隔、参考卫星的选择进行了研究,重点对比分析了各种基线解算方案对基线解算结果的影响,为使用者进行GPS基线解算提供有益的参考。通过实验数据的对比分析可知:在用软件进行基线解算时,需要综合考虑卫星数目的多少、同步观测时间,以及卫星的追踪总结图等。 相似文献
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