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41.
42.
宁晰春 《地球科学与环境学报》1987,(1)
形成旋扭构造的动力可概括为五个方面:地块随着地球自转速率的变化,局部发生的旋扭;漂移在软流圈之上的地块遇到上拱的“热柱”受到局部牵制而旋扭;地幔熔融体物质对流循环产生蠕动式旋扭;岩石圈拖曳牵动引起旋扭;重力控制下密度分异所引起的水平漫流碰接于上升物质而旋转。欧亚大陆上分布着涡轮状、帚状、莲花状、连环状等各种旋扭构造。 相似文献
43.
夏季辽东湾西部海域大型底栖动物群落结构与多样性 总被引:1,自引:0,他引:1
为了解夏季辽东湾西部海域大型底栖动物群落结构与多样性,作者于2009年8月对六股河口外海域15个站位进行了大型底栖动物调查。整个研究海域共采到大型底栖动物124种,其总平均丰度为(2824±1537)个/m2,总平均生物量为(22.01±38.58)g/m2。利用相对重要性指数和优势度指数所确定的前三位优势种一致,分别为二齿半尖额涟虫(Hemileucon bidentatus)、深钩毛虫(Sigambra bassi)和独指虫(Aricidea fragilis),其余优势种存在细微差异。各站位香农-维纳多样性指数、Pielou均匀度指数和Margalef丰富度指数均呈现河口和中部海域低,近岸和外围海域高的分布规律。在50%相似度水平上,可将研究海域划分为4个群落。研究结果表明:研究海域底栖环境整体清洁,底层水环境因子对大型底栖动物群落的影响较弱。 相似文献
44.
Ma Jun Song Jinming Li Xuegang Yuan Huamao Li Ning Duan Liqin Wang Qidong 《中国海洋湖沼学报》2020,38(4):1215-1224
An investigation was carried out in the Y3 seamount area of the Western Pacific Ocean in December 2014,and the distribution of dissolved inorganic carbon(DIC) and its relationship with environmental factors in this area were explored.The results show that DIC concentration was higher in the adjacent waters of the Y3 seamount area,and the uplift of DIC isolines at the stations was close to the seamount.Meanwhile,interaction between the North Equatorial Current(NEC) and the Y3 seamount affected the DIC distribution i.e.,the upwelling in the same direction of the NEC was obvious,resulting in a decreasing trend of average concentration of DIC in the 200 m water column from the top to the two side s in this direction but in the cross direction.The DIC concentration increased with the water depth increase,and its distribution was affected by various environmental factors.In the surface water,high temperature was a decisive factor for the decrease of the DIC concentration,but the photosynthesis of phytoplankton showing only a weak influence.In the North Pacific Tropic Water(NPTW),DIC production rate from organic matter decomposition was higher than that of DIC consumption by phytoplankton photosynthesis,leading to a continual increase of DIC.In the North Pacific Intermediate Water(NPIW),organic matter decomposition played a leading role in the increase of DIC.In the deep water,decomposition of organic matter weakened,and the dissolution of CaCO_3 controlled the carbonate system,and DIC had the smallest variation range. 相似文献
45.
Scapharca broughtonii is a commercially important and over-exploited species. In order to investigate its genetic diversity and population structure, 43 novel polymorphic microsatellites were isolated and characterized. The number of alleles per locus ranged from 3 to 22 with an average of 6.93, and the observed and expected heterozygosities varied between 0.233 and 1.000, and 0.250 and 0.953, with an average of 0.614 and 0.707, respectively. Three highly informative multiplex PCRs were developed from nine of those microsatellites for S. broughtonii. We evaluated and validated these multiplex PCRs in 8 full-sib families. The average polymorphism information content (PIC) was 0.539. The frequency of null alleles was estimated as 3.13% of all the alleles segregation based on a within-family analysis of Mendelian segregation patterns. Parentage analysis of real offspring demonstrated that 100% of all offspring were unambiguously allocated to a pair of parents based on 3 multiplex sets. Those 43 microsatellite loci with high variability will be helpful for the analysis of population genetics and conservation of wild stock of S. broughtonii. The 3 sets of multiplex PCRs could be an important tool of pedigree reconstruction, population genetic analysis and brood stock management. 相似文献
46.
47.
The Kungurian-Capitanian ( Permian) Zhesi branchiopod fauna is mainly composed of cold-water typed taxa with high diversity and abundance. This fauna is similar with the coeval brachiopod faunas from Timan-Pechora,Svalbard,and Queen Elizabeth Islands of the Boreal Realm,with no real"warm-water"species. Zhesi brachiopod fauna is a cold-water fauna and should be assigned to the Boreal Realm. Considering the paleogeographic characteristics of this fauna and the basic rationale of paleobiogeographic provinces being controlled by latitude-temperate,and that the above areas were located at 50°N 70°N in the global paleoclimate reconstruction map compiled by Boucot et al. ,the paleo-latitude of the southern margin of Jiamusi-Mongolia Block,where developed the Zhesi brachiopod fauna,is suggested ranging from 40°N to 60°N. Zhesi brachiopod fauna is an endemic fauna,containing more than 75% endemic species and self-grouped as a biogeographic province,termed Inner Mongolia Province. These characteristics indicate that this area was closed or semiclosed at that time. On the Jiamusi-Mongolia Block,the Herlen-Jiamusi Old-land as an obvious "continental barrier"hindered the northward migration of the Zhesi brachiopod fauna and the immigration of brachiopod species from other areas. The Tarim plate has collided with the Kazakhstan plate and the western part of South Tianshan-Beishan-Xar Moron Ocean has been closed. At the same time,the western margin of Jiamusi-Mongolia Block was joined with the Tarim plate. The Xar Moron Ocean in south of Jiamusi-Mongolia Block was wide enough and the ocean temperature rose gradually southward,so that it is not suitable for the cold-water brachiopods to survive and thrive on the northern margin of the North China plate. Thus,the ocean with large width and high temperature formed another natural barrier for the southward migration of the cold-water brachiopods. 相似文献
48.
????GM(1,1)?????????????????????????????????????????GM(1,1)?????????????????????????GM(1,1) ??????GM(1,1)??PGM(1,1)?????GM(1,1)????????????б???????????????????????GM(1,1)???????????? 相似文献
49.
提出参照标准点探测PS法。既考虑PS的强散射特性,又顾及其稳定性,且初选时振幅阈值的设置参照每景影像中PS标准点的振幅值,精选时振幅离差阈值的设置也参照这些PS标准点的振幅离差值,都不需要人工设定。选取澳门半岛为实验区,以18景TerraSAR-X为数据源,进行PS探测实验。结果表明,相比于传统的PS探测方法,本方法能更快速、有效、可靠地探测出SAR影像中的PS。 相似文献
50.
1998-2002年中国地表太阳辐射的时空变化分析 总被引:2,自引:0,他引:2
地表太阳辐射是陆气能量交换过程中重要的物理参数和生态参数,利用卫星数据反演地表太阳辐射对于全面认识地表太阳辐射空间差异性和年际变化特征具有重要的意义。本文利用GMS-5静止气象卫星数据反演了中国区域1998-2002年地表太阳辐射值,在此基础上分析了我国地表太阳辐射的时空分布特征。结果表明:(1)青藏高原的地表太阳辐射最大,川黔地区最小,都位于北纬22~35°这一带除川黔地区外,地表太阳辐射从东向西增强,西部随纬度升高而减小,东部以长江流域最小,向南北增加,西南最大,北部次之,至东北地区随纬度升高而减小(2)各月地表太阳辐射量分布复杂,最小值都出现在12月,但最大值出现时间受雨季影响很大,珠江、长江一带主要在雨季过后的7月,华北、东北和青藏高原主要出现在雨季前的6月及5月,西南地区则在季风雨季前的4-5月(3)5年来东部沿海地区地表太阳辐射增加了13.71%(+4.37W/m2·a),西藏高原地区地表太阳辐射减少了9.31%(-3.47W/m2·a),全国地表太阳辐射平均减少了0.84%(-0.27W/m2·a)。 相似文献