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981.
三疣梭子蟹病原副溶血弧菌的分离与鉴定 总被引:2,自引:0,他引:2
从养殖病死三疣梭子蟹肝胰脏及心脏血淋巴液中分离到大量优势生长的细菌,人工感染试验证明分离菌对三疣梭子蟹有较强的致病性;对分离菌进行了形态特征、理化特性、胞外酶及溶血素活性等表型生物学性状及16S rRNA和gyrB两种基因的分子鉴定。菌株(JGX080708-1)所扩增的16S rRNA基因序列长度为1453bp(GenBank登录号:FJ824663),所扩增的gyrB基因序列长度为1191bp(GenBank登录号:GQ372985);两种基因序列在NCBI通过blast检索,结果均与弧菌属细菌的基因序列自然聚类;根据分离菌的表型及分子特征,判定分离菌为弧菌属(Vibrio Pacini1954)的副溶血弧菌[Vibrio parahaemolyticus(Fujino et al1951)Sakazaki Nakamura and Takizawa1963]。分离菌的药敏试验结果显示,对供试49种抗菌药物中的安曲南等42种药物高度敏感,对林可霉素敏感,对青霉素G等6种药物耐药。 相似文献
982.
大地水准面(数字高程基准)为国家高程基准的建立与维持提供了全新的思路。然而,受限于地形、重力数据等原因,高原地区高精度数字高程基准模型的建立一直是大地测量领域的难题。本文以格尔木地区为例,探讨了高原地区高精度数字高程基准模型的建立方法。首先,基于重力和地形数据,由第二类Helmert凝集法计算了格尔木重力似大地水准面。在计算中,考虑到高原地形对大地水准面模型的影响,采用了7.5″×7.5″分辨率和高精度的地形数据来恢复大地水准面短波部分的方法,以提高似大地水准面的精度。然后,利用球冠谐调和分析方法将GNSS水准与重力似大地水准面联合,建立了格尔木高精度数字高程基准模型。与实测的67个高精度GNSS水准资料比较,重力似大地水准面的外符合精度为3.0 cm,数字高程基准模型的内符合精度为2.0 cm。 相似文献
983.
黄海苏北浅滩海域春夏季浮游植物时空分布及其控制生态因子 总被引:1,自引:0,他引:1
The Subei Shoal is a special coastal area with complex physical oceanographic properties in the Yellow Sea. In the present study, the distribution of phytoplankton and its correlation with environmental factors were studied during spring and summer of 2012 in the Subei Shoal of the Yellow Sea. Phytoplankton species composition and abundance data were accomplished by Uterm?hl method. Diatoms represented the greatest cellular abundance during the study period. In spring, the phytoplankton cell abundance ranged from 1.59×10~3 to 269.78×10~3 cell/L with an average of 41.80×10~3 cell/L, and Skeletonema sp. and Paralia sulcata was the most dominant species. In summer, the average phytoplankton cell abundance was 72.59×10~3 cell/L with the range of 1.78×10~3 to 574.96×10~3 cell/L, and the main dominant species was Pseudo-nitzschia pungens, Skeletonema sp., Dactyliosolen fragilissima and Chaetoceros curvisetus. The results of a redundancy analysis(RDA) showed that turbidity,temperature, salinity, pH, dissolved oxygen(DO), the ratio of dissolved inorganic nitrogen to silicate and SiO_4-Si(DIN/SiO_4-Si) were the most important environmental factors controlling phytoplankton assemblages in spring or summer in the Subei Shoal of the Yellow Sea. 相似文献
984.
LIU Shengcong BI Chunwei YANG Hui HUANG Liuyi LIANG Zhenlin ZHAO Yunpeng 《中国海洋大学学报(英文版)》2019,(3):701-709
Submersible fish cages can be submerged under the water to mitigate the negative effects that arise from severe sea conditions and improve the growing environment for the farmed fish. Thus they are increasingly applied in offshore aquaculture. To ensure both safety and economic efficiency of submersible fish cages, it is important to determine the optimum submergence depth. In this study, a series of physical model experiments were conducted to investigate the hydrodynamic performance of a submersible fish cage at various submergence depths(1/6, 1/4, 1/3, and 1/2 of the water depth as well as the floating condition for reference) with a model scale of 1:20. The results of the physical model experiment for the different depths were compared to analyze the effects of submergence depths on the mooring line tension and the movement of the floating collar. The results showed that the mooring line tension and the floating collar movement significantly attenuated with increasing submergence depth. However, the attenuation tendency became stable when the fish cage reached a certain depth. According to the results, 1/3 of water depth was determined as the optimal submergence depth of the fish cages. Deeper submergence depths showed no significant advantage from a perspective of the hydrodynamic characteristics of the fish cage. The determination of the optimum submergence depth is beneficial for the structural design and operation safety of submersible net cages. 相似文献
985.
Arrays of baffles are usually installed in front of protection site to attenuate the flow energy of rock avalanches in mountainous areas. Optimization design is crucial for efficiency promotion in hazard energy dissipation engineering. In this study, a deceleration strip was added in the baffles protection system to optimize the traditional baffles system. The effects of the "baffles-deceleration strip" hybrid protection system was discussed in detail with the nails number and nails angle. This study presents details of numerical experiments using the discreteelement method(DEM). The effect of the optimization of hybrid protection system(nail angle and nail number) were investigated specifically, especially the impact force that avalanches exerted on structures. The results show that the maximum impact forces and kinetic energy of the rock avalanches decreases with the increase of the number and angle of the nail. Moreover, the distance between the toe and the bearing structure(L_m) is also a key factor. The shorter the distance L_m(30 m) is, the higher the maximum impact force are. The longer the distance L_m(70 m) is, the lower the maximum impact force are. Under the same size of the nails, increasing the numbers can enhance the dissipation ability of the hybrid protection system. Meanwhile, increasing itsangle can also enhance the dissipation ability. There are three key ways for nails attenuate rock avalanches:(i) block the fine particles directly;(ii) form the particles bridge between nails and baffles;(iii) dissipate the coarse particles energy directly. The effect of segregation in rock avalanches is crucial for the energy dissipation mechanism, which is a key factor to optimize the traditional baffle system. 相似文献
986.
贫金属富碳恒星(Carbon-Enhanced Metal-Poor, CEMP)是研究宇宙早期恒星性质和化学演化的极佳样本,通常认为来自双星.目前发现的贫金属富碳星中有9颗天琴RR变星(RR Lyrae star, RRL),其中至少7颗未表现出任何双星特征.传统双星物质转移模型不足以充分解释贫金属富碳天琴RR变星(CEMP-RR Lyrae)单星的形成.之前研究表明氦白矮星和赫氏空隙星(HG)的并合模型可以解释部分富碳红巨星单星的碳增丰现象,因此贫金属富碳星单星也可能来自氦白矮星和赫氏空隙星的并合模型渠道.通过详细计算的氦白矮星和赫氏空隙星并合模型来检验这一演化渠道,结果表明:该并合模型在后续的演化过程中,其重力加速度、温度、表面碳丰度均能与观测符合较好.由此,氦白矮星和赫氏空隙星并合模型极有可能是贫金属富碳天琴RR变星的形成渠道之一. 相似文献
987.
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989.
田野考古信息系统的主要研究内容包括探方剖面图、底面图线图的自动获取与数据处理;通过线图等资料构建发掘现场的原始三维场景,再现人类古环境;将近景摄影测量技术、无线网络传输系统和GPS、GIS的数据相融合,建立空间数据快速采集集成处理系统等集群技术。本文给出了该三组集群技术的设计方案,同时设计出了三维空间数据采集与处理、三维体视化与无线网协同工作、虚拟环境构建与空间决策支持系统建立三个研究阶段的主要实施流程。已完成的第一阶段与第二阶段的部分研究成果表明,该系统的设计方案与实施流程是正确的、可行的。 相似文献
990.