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141.
As an important measurement parameter, global total electron content (TEC) is appropriate for the study of the Sun–Earth connection.
In this paper, the wavelet technique is employed to investigate the periodicities in global mean TEC during 1995–2008. Analysis
results show several remarkable components (including 27-day, semiannual and annual cycles) existing in global mean TEC with
obvious time-variable characteristics, besides 11-year cycle. After analyzing sunspot numbers and solar extreme ultra-violet
(EUV) radiation variations during this time period, except for semiannual variations, close correlation between global mean
TEC and solar variations is found, especially, a strong resemblance of the 27-day fluctuation exists in global mean TEC, sunspot
and solar EUV radiation variations. 相似文献
142.
A 3×3 complete diallel cross comprising three families of the clam Meretrix meretrix(P1, P2 and P3) was used to determine the combining ability of parental families and heterosis of F1 under indoor and openair environments for growth traits. Analysis of variance for shell length and whole body weight indicated highly significant cross effects, environment effects and the interaction of cross by environment. General combining ability(GCA) and specific combing ability exhibited great variation among crosses and between two environments. Pooled over environments, P2 was the top combiner among the three parental families for both traits studied. The cross of P1 and P3 had the highest SCA. Additionally, significant reciprocal effects were observed. For individual environment, about half of the crossbred combinations showed favorable Mid-parent heterosis(MPH)(1%) for the shell length and whole body weight. Our data has shown that non-additive genetic and reciprocal effects constituted the major sources of genetic variation for both shell length and whole body weight, which indicates that crossbreeding among selective families could further explore the heterotic effects. 相似文献
143.
为了解南海北部陆缘古双峰-笔架碰撞造山带空间延伸范围、褶皱和断裂构造发育特征,通过对研究区22条多道反射地震剖面资料的地层-构造解释,结合钻井岩石地层资料的综合解释,运用构造解析分析法、筛选法以及回剥法对位于南海北部陆缘的古双峰-笔架碰撞造山带的构造几何学基本特征进行了研究。综合分析筛除了新生代构造沉降量后的新生代地层底界面(反射地震Tg界面)的空间起伏形态特征和前新生代地层变形特征发现,古双峰-笔架碰撞造山带呈NEE向展布,其核部位于珠江口盆地东南部的陆洋过渡带下陆坡位置,即06号测线所在位置及其附近,琼东南盆地为造山带的NWW翼。此研究结果可为南海地区前新生代晚期大地构造格局重建、南海成因机制研究提供构造事实观测依据。 相似文献
144.
145.
Juan Chen Fei-Hua Wu Qiang Xiao Zhang-Hua Yang Sheng-Kai Huang Jian Wang Yu-Guang Wu Xue-Jun Dong Zhen-Ming Pei Hai-Lei Zheng 《Estuarine, Coastal and Shelf Science》2010
The diurnal variation of nitric oxide (NO) emission fluxes from a Kandelia obovata and Avicennia marina mangrove wetland were studied in the Zhangjiang River Estuary Mangrove National Nature Reserve using a dynamic chamber-based technique and a chemiluminescent analyzer. Results from field experiments show that NO emission from K. obovata and A. marina sampling sites reached maximal values of 1.07 ng N m−2 s−1 and 1.23 ng N m−2 s−1, respectively after the night tide. Meanwhile NO emission maintained at a steady lower level in daytime for both wetland sites. In laboratory experiments, NO emission from the mangrove wetland soil samples treated with simulated tides in the darkness exhibited higher values than those in the light, therefore it seems that tides and darkness could increase NO emission from mangrove wetlands, while intensive light, high temperature, and dryness in the daytime decreased NO emission. Compared with K. obovata soil samples, the diurnal average NO emission rate of the A. marina site was significantly higher, which was closely related to relatively higher diurnal average CO2 emission rate, soil available nitrogen content and soil net nitrification rate of the A. marina site. Moreover, soil samples of the A. marina site were more responsive to simulated tides and the addition of nitrogen than those of the K. obovata site. 相似文献
146.
现行黄河三角洲地貌演化已使河口动力环境发生了显著变化,但黄河改道清8汊后,现行河口以及废弃河道清水沟河口动力环境如何变化尚不清楚。基于1976、1995和2002年黄河三角洲实测水深数据,应用Delft3D模型对清水沟流路不同时期冬夏季河口动力环境进行了数值模拟,定量研究了黄河三角洲地貌演化对动力环境的影响。模拟结果表明,黄河现行三角洲地貌演化导致河口动力环境发生了显著变化,1976年河口动力环境弱,随着河嘴向海突出,1995年河口处涨、落潮最大流速较1976年增长了约60%~90%,潮致剪切力增大约2倍,冬季大风条件下浪致剪切力较1976年增加1个数量级,2002年黄河改道清8汊入海后,现行河口处涨、落潮最大流速较1995年减小约20%,潮致剪切力减小1/3,冬季大风条件下浪致剪切力是1995年的1~2倍,而废弃河道河口处涨、落潮最大流速较1995年减小约20%~40%,潮致剪切力减小约20%。黄河三角洲动力环境变化也显著影响了入海泥沙的搬运与沉积,造成清水沟河口呈“南肥北瘦”形态,且废弃后侵蚀速率不断降低。同时,地貌形态与动力环境之间的耦合关系对黄河三角洲冲淤模式的转变有重要影响。 相似文献
147.
148.
Hyun Suk Park Choong-Gon Kim Sung Kim Yong-Joo Park Hee-Jung Choi Zhizhong Xiao Jun Li Yongshuang Xiao Youn-Ho Lee 《Ocean Science Journal》2018,53(2):261-274
The rock bream, Oplegnathus fasciatus, is a common rocky reef game fish in East Asia and recently has become an aquaculture species. Despite its commercial importance, the population genetic structure of this fish species remains poorly understood. In this study, 163 specimens were collected from 6 localities along the coastal waters of Korea and China and their genetic variation was analyzed with mtDNA COI sequences. A total of 34 polymorphic sites were detected which determined 30 haplotypes. The genetic pattern reveals a low level of nucleotide diversity (0.04 ± 0.003) but a high level of haplotype diversity (0.83 ± 0.02). The 30 haplotypes are divided into two major genealogical clades: one that consists of only Zhoushan (ZS, East China Sea) specific haplotypes from the southern East China Sea and the other that consists of the remaining haplotypes from the northern East China Sea, Yellow Sea, Korea Strait, and East Sea/Sea of Japan. The two clades are separated by approximately 330~435 kyBP. Analyses of AMOVA and Fst show a significant population differentiation between the ZS sample and the other ones, corroborating separation of the two genealogical clades. Larval dispersal and the fresh Yangtze River plume are invoked as the main determining factors for this population genetic structure of O. fasciatus. Neutrality tests and mismatch distribution analyses indicate late Pleistocene population expansion along the coastal waters of Korea and China approximately 133–183 kyBP during which there were periodic cycles of glaciations and deglaciations. Such population information needs to be taken into account when stock enhancement and conservation measures are implemented for this fisheries species. 相似文献
149.
-Combined refraction and diffraction models in the form of linear parabolic approximation are derived through smallparameter method. More strictly theoretical basis and more accuracy in the models than Lozano's (1980) are obtained. Some theoretical defects in Liu's model (1985) with consideration of current are not only found but also eliminated. More strict and accurate models are, therefore, presented in this paper.The calculation results and analysis in applying the models to actual wave field with consideration of bottom friction will be given in the following paper. 相似文献
150.
Spatial and temporal variations of mesozooplankton in the Pearl River estuary, China 总被引:10,自引:0,他引:10
This paper examines spatial and temporal variations of mesozooplankton abundance, biomass and community structure during three cruises of July 2002 (summer), January 2003 (winter), and April 2003 (spring) in the Pearl River estuary, China. Zooplankton abundance and biomass fluctuated widely and showed distinct heterogeneity in the Pearl River estuary. A total of 154 species were identified during three surveys. The number of zooplankton species richness was strongly linked to salinity. Hierarchical cluster analysis identified three zooplankton groups during this study. Estuarine, neritic and pelagic groups corresponded to the upper, middle and lower reaches in the Pearl River estuary. The difference among groups could be mainly ascribed to changes in the relative contributions of the dominant species. The fluctuations in the zooplankton abundance, biomass and community structure were determined by the interactive effects of freshwater inflow, tidal and coastal currents, chlorophyll a, salinity and temperature. Significant spatial variability in the distribution of zooplankton species, abundance and biomass can be ascribed to the virtual presence of a horizontal gradient in salinity. 相似文献