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第一类华结构Bergman核函数的无穷级数和形式 被引量:1
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作者 李庆宾 薛均晓 《佳木斯大学学报(自然科学版)》 CAS 2009年第6期927-930,935,共5页
第一类华结构Bergman核函数的高维超几何函数形式和有限和形式都是在其无穷级数和形式的基础上,对指标p1,p2,…,pn分别进行某些限制,从而计算得到的.本文给出了一般情况下第一类华结构Bergman核函数的无穷级数和形式.
关键词 华结构 BERGMAN核函数 超几何函数
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第一类华结构上超几何函数形式的Bergman核函数
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作者 李庆宾 薛均晓 《佳木斯大学学报(自然科学版)》 CAS 2010年第3期453-455,共3页
利用第一类华结构的完备规范正交系和它的全纯自同构群,通过一些特殊的Γ函数关系式以及一些计算技巧,得到了当1/p1,…,1/pr-1为正整数,pr为任意正实数时,第一类华结构Bergman核函数的高维超几何函数形式.
关键词 CARTAN域 华结构 BERGMAN核函数
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第二类华结构的Einstein-Khler度量及其全纯截曲率 被引量:1
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作者 徐宁 《徐州师范大学学报(自然科学版)》 CAS 2008年第3期19-23,28,共6页
给出一类特殊第二类华结构HCⅡp((p+1)/4+1,p+1/2)的Einstein-Khler度量的显表达式,并计算了在此度量下的全纯截曲率.此时HCⅡ一般而言是非齐性的.
关键词 华结构 Einstein—Kahler度量 生成函数 全纯截曲率
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适合中国国情的“华式结构功能法”
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作者 田式国 《山东教育学院学报》 2001年第3期59-61,共3页
本文介绍了“华式结构功能法”的形成背景、教学观点、教学模式和教学技巧。该教学法是在吸取国内外其他外语教学法的合理成分 ,密切结合我国外语教育教学的实际 ,经过十多年的实践与研究后逐步形成的。目前 ,该法已形成自身较为完整的... 本文介绍了“华式结构功能法”的形成背景、教学观点、教学模式和教学技巧。该教学法是在吸取国内外其他外语教学法的合理成分 ,密切结合我国外语教育教学的实际 ,经过十多年的实践与研究后逐步形成的。目前 ,该法已形成自身较为完整的体系 。 展开更多
关键词 教学法 翻译法 教学模式 中国 外语教学 教学技巧 "结构功能法" 语境教学
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Anatomy, Histochemistry and Phytochemistry of Leaves in Aloe vera var. chinensis 被引量:5
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作者 沈宗根 Elena CHAUSER-VOLFSON +1 位作者 Yitzchak GUTTERMAN 胡正海 《Acta Botanica Sinica》 CSCD 2001年第8期780-787,共8页
A multidisciplinary approach-anatomy, histochemistry and phytochemistry-was used to investigate the leaf structure, the content and the storage location of barbaloin in the leaves of Aloe vera L. var. chinensis (Haw.)... A multidisciplinary approach-anatomy, histochemistry and phytochemistry-was used to investigate the leaf structure, the content and the storage location of barbaloin in the leaves of Aloe vera L. var. chinensis (Haw.) Berg. Xeromorphic characteristics including secondary thickened epidermal cell walls, thicker cuticle, ambiguous differentiation of spongy and palisade tissues in the chlorenchyma, and well-developed aquiferous tissue could be seen in the leaves. Several large parenchymatous cells were observed at the phloem pole of the first ring of vascular bundles. The secondary ring of vascular bundles in the leaf base and the stomata, which are surrounded by five cells, have some classification significance in this species. The density of vascular bundles, the content of barbaloin and the intensity of histochemical reaction differed among leaf numbers Ll (annual leaf), L2 (biennial leaf), L3 (triennial leaf) and L4 (quadrennial leaf), and in different parts of the leaf. These three factors were highest in the youngest leaf, Ll, and top parts of all the leaves and lowest in the basal parts and the oldest leaf, L4. The density of vascular bundles had a positive correlation to the content of barbaloin. The histochemical results revealed that the small sheath cells that surrounded the bundles might be the location of barbaloin synthesis and the large parenchymatous cells beneath the sheath might be the storage places of this metabolite. 展开更多
关键词 Aloe vera var. chinensis leaf structure barbaloin content density of vascular bundles histochemical reaction
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组合墙体的弯曲承载能力
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作者 李兆华 陈忠范 《工程力学》 EI CSCD 北大核心 2000年第A01期710-715,共6页
组合墙体是由钢筋混凝土边框包围内部砌体半考虑其共同工作性能的一种新型的砌体结构,本文在试验研究和弹塑性有限元分析的基础上,推导了此类 砌体在两种情形下的抗弯承载力公式。本文公式的计算结果与有限元结果相对比,具有料好的... 组合墙体是由钢筋混凝土边框包围内部砌体半考虑其共同工作性能的一种新型的砌体结构,本文在试验研究和弹塑性有限元分析的基础上,推导了此类 砌体在两种情形下的抗弯承载力公式。本文公式的计算结果与有限元结果相对比,具有料好的精度。 展开更多
关键词 组合墙体 抗弯承载力 协同工作 华结构
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STUDY ON THE MORPHOLOGY OF LIPS AND ASSOCIATED STRUCTURES IN THE CYPRINID GENUS Parasinilabeo
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作者 张鹗 《Zoological Research》 CAS CSCD 1998年第1期52-58,共7页
The comparative morphology of the lips and associated structures is studied among Parasinilabeo and its taxonomically related groups. On the basis of the morphological features of the lips and associated structure... The comparative morphology of the lips and associated structures is studied among Parasinilabeo and its taxonomically related groups. On the basis of the morphological features of the lips and associated structures, Parasinilabeo is proposed to be closely associated with Pseudogyrinocheilus and Semilabeo ;and four typical mouth patterns are identifled among Parasinilabeo and its taxonomically related groups. 展开更多
关键词 Parasinilabeo Lips and associated structures MORPHOLOGY
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Prediction of Secondary Structure and B Cell Epitope of GH Protein from Acipenser sinensis 被引量:3
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作者 刘红艳 杨东 +1 位作者 张繁荣 余来宁 《Agricultural Science & Technology》 CAS 2009年第2期46-48,58,共4页
[ Objective] The aim was to predict the secondary structure and B cell epitope of growth hormone (GH) protein from Acipenser sinensis. [Method] With the amino acid sequence of GH protein from A. sinensis as the base... [ Objective] The aim was to predict the secondary structure and B cell epitope of growth hormone (GH) protein from Acipenser sinensis. [Method] With the amino acid sequence of GH protein from A. sinensis as the base, the secondary structure of GH protein from A. sinensis was predicted by the method of Gamier-Robson, Chou-Fasman and Karpius-Schulz, and its cell epitope was predicted by the method of Kyte- Doolittle, Emini and Jameson-Wolf. [Result] The sections of 18 -23, 55 -55, 67 -73, 83 -86,112 -114,151 -157 and 209 -211 in the N terminal of GH protein molecule had softer structure and these sections could sway or fold to produce more complex tertiary structure. The sections of 19 -23, 51 -71,84 -95, 128 -139, 164 -176 and 189 -195 in the N terminal of GH protein could be the epitope of B cell and there were flexible regions in these sections or near these sections of GH protein molecule. So the dominant regions could be in these sections or near these sections. [ Conclusion] The research provided the basis for the preparation of monoctonal antibody of GH protein from A. sinensis and provided the reference for the discussion for the molecular regulation mechanism of A. sinensis. 展开更多
关键词 Acipenser sinensis GH protein Secondary structure Cell epitope
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Simulated Annealing Study on Structures and Energetics of CO2 in Argon Clusters
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作者 王乐成 谢代前 《Chinese Journal of Chemical Physics》 SCIE CAS CSCD 2011年第5期620-624,I0004,共6页
The minimum-energy configurations and energetic properties of the ArN-CO2 (N=1-19) van der Waals clusters were investigated by a simulated annealing algorithm. A newly developed Ar-CO2 potential energy surface toget... The minimum-energy configurations and energetic properties of the ArN-CO2 (N=1-19) van der Waals clusters were investigated by a simulated annealing algorithm. A newly developed Ar-CO2 potential energy surface together with the Aziz Ar-Ar interaction potential was employed to construct the high dimensional potential functions by pairwise additive approximation. The global minimal conformations were optimized by sampling the glassy phase space with a circumspectively formulated annealing schedule. Unlike the lighter agg-CO2 clusters, the size-dependent structural and energetic characteristics of ArN-CO2 exhibit a different behavior. The dramatically variations with number of solvent were found for small clusters. After the completion of the first solvation shell at N=17, the clusters were evolved more smoothly. 展开更多
关键词 Molecular structure van der Waals cluster Simulated annealing algorithm
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Food web structure and trophic levels in polyculture ricecrab fields 被引量:4
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作者 郭凯 赵文 +3 位作者 李文宽 赵苑淞 张鹏 张晨 《Chinese Journal of Oceanology and Limnology》 SCIE CAS CSCD 2015年第3期735-740,共6页
Stable carbon and nitrogen isotopes were used to investigate nutrient pathways and trophic relationships from the rice-crab system in Panjin, Liaoning Province, China. Values of 313C ranged from -27.38%±0.44%o to... Stable carbon and nitrogen isotopes were used to investigate nutrient pathways and trophic relationships from the rice-crab system in Panjin, Liaoning Province, China. Values of 313C ranged from -27.38%±0.44%o to -18.34%±0.26%o and δ^15N ranged from 1.10%o4-0.88%o to 9.33%±0.57%. Pseudorasbora parva (Stone moroko) had the highest δ^13C and 8tSN values. The lowest δ^13C values were obtained for the macrophytes and the lowest δ^15N value was found in sediments. Stable carbon and nitrogen isotopes were used to determine the contribution of different food items to the diets of crabs. The δ^13C results indicated that the Pseudorasbora parva made the greatest contribution to the diet of Eriocheir sinensis (Chinese mitten crab), while the δ^15N results indicated that most food items contributed more than 10% to the diet of the crab. There were three trophic levels identified in the system (Levels 0-2). The crab Eriocheir sinensis, fish Pseudorasbora parva and Misgurnus anguillicaudatus (Oriental weatherfish), and the oligochaete Limnodrilus hoffmeisteri (Limnodrilus worm), were at the second level, zooplankton were at the first level and suspended particulate matter and macrophytes were at trophic position 0. 展开更多
关键词 rice-crab culture Eriocheir sinens stable carbon isotope stable nitrogen isotope trophic level
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Research and development of seismic base isolation technique for civil engineering structures 被引量:1
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作者 Zhu Hongping Mei Shilong +2 位作者 Li Li Ye Kun Yuan Yong 《Engineering Sciences》 EI 2010年第1期16-21,共6页
Base isolation is one of the most promising alternatives among the structure control methods. In recent decades, base isolation has been seriously considered for civil structures, such as buildings and bridges, subjec... Base isolation is one of the most promising alternatives among the structure control methods. In recent decades, base isolation has been seriously considered for civil structures, such as buildings and bridges, subjected to ground motion. The research achievements and development of seismic base isolation technique for civil structures in Huazhong University of Science and Technology (HUST) are introduced. The achievements include project applications, experimental research results and theoretical innovation. 展开更多
关键词 seismic base isolation civil structures DEVELOPMENT APPLICATION
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Changes in phytoplankton communities along nutrient gradients in Lake Taihu:evidence for nutrient reduction strategies 被引量:1
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作者 艾鹰 毕永红 胡征宇 《Chinese Journal of Oceanology and Limnology》 SCIE CAS CSCD 2015年第2期447-457,共11页
An annual investigation on phytoplankton communities was conducted to reveal the effects of nutrients on phytoplankton assemblages in Lake Taihu,East China. A total of 78 phytoplankton taxa were identified. Phytoplank... An annual investigation on phytoplankton communities was conducted to reveal the effects of nutrients on phytoplankton assemblages in Lake Taihu,East China. A total of 78 phytoplankton taxa were identified. Phytoplankton biomass was higher in the northern part of the lake than in the southern part. Cyanobacteria and Bacillariophyta alternated dominance in the northern area,where algal blooms often appear,and co-dominated in the southern area. In the northern part,the proportions of cyanobacteria and Bacillariophyta varied significantly in total biovolume,both along the phosphorus(P) gradient,and between total nitrogen levels(≤3 mg/L and >3 mg/L TN). The proportions of cyanobacteria and Bacillariophyta had no signif icant variations in total biovolume along P and N(nitrogen) gradients in the southern part. Correlation analysis and CCA results revealed that P was the key factor regulating phytoplankton community structure. Nitrogen was also important for the phytoplankton distribution pattern. It was concluded that nutrient structure was heterogeneous in space and shaped the distribution pattern of phytoplankton in the lake. Both exogenous P and internally sourced Prelease needs to be considered. N reduction should be considered simultaneously with P control to efficiently reduce eutrophication and algal blooms. 展开更多
关键词 phytoplankton community nutrient gradient PHOSPHORUS nitrogen Taihu Lake
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Annual variation in Calanus sinicus abundance and population structure in the northern boundary area of the Yellow Sea Cold Water Mass 被引量:2
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作者 尹洁慧 张光涛 +2 位作者 赵增霞 王世伟 万艾勇 《Chinese Journal of Oceanology and Limnology》 SCIE CAS CSCD 2013年第6期1284-1294,共11页
The Yellow Sea Cold Water Mass (YSCWM) was suggested as an over-summering site of the dominant copepod species Calanus sinicus in coastal Chinese seas. Population abundance and structure were investigated by monthly... The Yellow Sea Cold Water Mass (YSCWM) was suggested as an over-summering site of the dominant copepod species Calanus sinicus in coastal Chinese seas. Population abundance and structure were investigated by monthly sampling along three transects across the northern boundary of the YSCWM during 2009-2010. Results show that thermal stratification existed from June to October and that the vertical thermal difference increased with depth. Generally, total abundance was lowest in October and highest in June, and the female/male sex ratio was highest in February and lowest in August. Evident spatial differences in abundance were observed during the existence of the YSCWM. In June, total abundance averaged 158.8 ind/m~ at well-stratified stations, and 532.1 ind/m3 at other stations. Similarly, high abundances of 322.0 and 324.4 ind/m3 were recorded from July to August inside the YSCWM, while the abundance decreased from 50.4 to 1.9 ind/m3 outside the water mass. C. sinicus distribution tended to even out over the study area in September when the YSCWM disappeared. We believe that the YSCWM may retard population recruitment in spring and preserve abundant cohorts in summer. The summer population was transported to neritic waters in autumn. In addition to low temperatures, stable vertical structure was also an essential condition for preservation of the summer population. C. sinicus can survive the summer in marginal areas in high abundance, but the population structure is completely different in terms of C5 proportion and sex ratio. 展开更多
关键词 Calanus sinicus Yellow Sea Cold Water Mass (YSCWM) over-summer strategy boundary area thermal stratification
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Estimation of main rheological parameters for Pangxidong-Jinkeng structural fracture zone and Qinzhou-Hangzhou metallogenetic belt in South China
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作者 HE Junguo 《Global Geology》 2013年第3期121-129,共9页
The mylonites occurred in the fracture zones are studied by dynamically recrystallized quartz grains.The natural microstructures in mylonites are simulated and the deformation conditions of mylonitization are estimate... The mylonites occurred in the fracture zones are studied by dynamically recrystallized quartz grains.The natural microstructures in mylonites are simulated and the deformation conditions of mylonitization are estimated by fractal analysis,recrystallized grain size paleopiezometer and flow laws of quartzite.Depending on fractal analysis,the deformation temperature of mylonitization is approximately 600℃,which presents high greenschist facies to low amphibolite facies.The mylonitization occurred at differential stresses of 9.1--10.7MPa(lower limits).Compared with extrapolation of quartzite flow laws and estimates of fractal analysis,the strain rate of mylonitization is under 10-13.8/s. 展开更多
关键词 recrystallized quartz grains MYLONITE fractal analysis deformation condition Pangxidong-Jinkeng structural fracture zone
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Frontier Research in Hand, National Demands in Mind——An Interview with XIONG Ke, Director of the State Key Laboratory of Mechanics and Control of Mechanical Structures-
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作者 XIONG Ke 《Aerospace China》 2016年第3期44-47,共4页
·Prof.XIONG,could you please give us a brief introduction to SKLMCMS?Director XIONG Ke:The State Key Laboratory of Mechanics and Control of Mechanical Structures(SKLMCMS)was established with the approval of t... ·Prof.XIONG,could you please give us a brief introduction to SKLMCMS?Director XIONG Ke:The State Key Laboratory of Mechanics and Control of Mechanical Structures(SKLMCMS)was established with the approval of the Ministry of Science and Technology of the People’s Republic of China in October 2011.The laboratory is located at Nanjing University of Aeronautics and Astronautics(NUAA). 展开更多
关键词 Director Frontier please approval aircraft Nanjing brief innovative disciplines astronautics
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Urban structural evolution over a century in Changchun city, Northeast China 被引量:6
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作者 匡文慧 颜凤芹 《Journal of Geographical Sciences》 SCIE CSCD 2018年第12期1877-1895,共19页
Knowledge on urban land-use change and its driving forces has vital significance in the practice of urban planning and management. However, the characteristics of historical, long-term changes and their quantitative r... Knowledge on urban land-use change and its driving forces has vital significance in the practice of urban planning and management. However, the characteristics of historical, long-term changes and their quantitative relationships with the urban environment are still poorly understood. Based on multi-source data, including remote sensing imageries, large-scale topographic maps, historical maps, multi-temporal city maps, and other urban thematic maps, high-quality spatial information on urban land use in the built-up area of Changchun has been extracted for 1898, 1932, 1954, 1976, 1990, 2002, and 2012 by means of geographic information systems and remote sensing. We found that the land-use structure and spatial configuration has undergone tremendous alterations according to urban function in the 100-year history of Changchun city. The built-up area of Changchun expanded from 2.26 km^2 in 1898 to 328.12 km^2 in 2012, increasing about 144 times over the past century. Historically, the development of Changchun can be categorized into three stages: the initial forming stage, the old industrial development stage, and the modern metropolis development stage. Commercial and industrial land expanded rapidly following the founding of the People's Republic of China in 1949, with an increase from 1.74 km^2 in 1954 to 15.91 km^2 in 2012, and from 16.45 km^2 in 1954 to 107.05 km^2 in 2012, respectively. Although there was substantial growth in residential land use(from 1.81 km^2 in 1898 to 113.95 km^2 in 2012), the area percentage of residential land decreased continuously(from 80.09% in 1898 to 34.73% in 2012). Moreover, it was noted that the spatial configuration and structural percentage for commercial, industrial, and residential lands and others had tremendous divergences at different stages. These divergences of land-use structure occurred between the stages and were associated with social regimes and the functional orientation of urban society across the 100 years of historical development. Socio-economics, population growth, and planning policies from specific stages, especially after 1949, had strong effects on the divergence of urban structure. 展开更多
关键词 urban expansion land use urban structure driving factors Changchun city China
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Regional differences in crustal structure of the North China Craton from receiver functions 被引量:20
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作者 WEI ZiGen CHU RiSheng CHEN Ling 《Science China Earth Sciences》 SCIE EI CAS CSCD 2015年第12期2200-2210,共11页
Moho depth and crustal average Poisson's ratio for 823 stations are obtained by H-n: stacking of receiver functions. These, to- gether with topography and receiver function amplitude information, were used to study ... Moho depth and crustal average Poisson's ratio for 823 stations are obtained by H-n: stacking of receiver functions. These, to- gether with topography and receiver function amplitude information, were used to study the crustal structure beneath the North China Craton (NCC). The results suggest that modified and preserved crust coexist beneath the craton with generally Airy-type isostatic equilibrium. The equilibrium is relatively low in the eastern NCC and some local areas in the central and western NCC, which correlates well with regional geology and tectonic features. Major differences in the crust were observed beneath the eastern, central, and western NCC, with average Moho depths of 33, 37, and 42 km and average Poisson's ratios of 0.268, 0.267 and 0.264, respectively. Abnormal Moho depths and Poisson's ratios are mainly present in the rift zones, the northern and southern edges of the central NCC, and tectonic boundaries. The crust beneath Ordos retains the characteristics of typical craton. Poisson's ratio increases roughly linearly as Moho depth decreases in all three parts of the NCC with different slopes. Receiver function amplitudes are relatively large in the northern edge of the eastern and central NCC, and small in and near the rifts. The Yanshan Mountains and southern part of the Shanxi rift show small-scale variations in the receiver-function ampli- tudes. These observations suggest that overall modification and thinning in the crust occurred in the eastern NCC, and local crustal modification occurred in the central and westem NCC. Different crustal structures in the eastern, central, and western NCC suggest different modification processes and mechanisms. The overall destruction of the crustal structure in the eastern NCC is probably due to the westward subduction of the Pacific Plate during the Meso-Cenozoic time; the local modifications of the crust in the central and western NCC may be due to repeated reactivations at zones with a heterogeneous structure by successive thermal-tectonic events during the long-term evolution of the NCC. 展开更多
关键词 North China Craton Moho depth Poisson's ratio gravitational equilibrium receiver function amplitude regional difference in crust
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The Emergence of Kingship in China: With a Discussion of the Relationship between Kingship and Composite State Structure in the Xia, Shang and Western Zhou Dynasties
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作者 Wang Zhenzhong 《Social Sciences in China》 2018年第2期5-21,共17页
In ancient China,true kingship was supreme rule over all under Heaven by the royal houses of the Xia,Shang and Western Zhou dynasties(the Three Dynasties).It was associated with the Three Dynasties’plural but unified... In ancient China,true kingship was supreme rule over all under Heaven by the royal houses of the Xia,Shang and Western Zhou dynasties(the Three Dynasties).It was associated with the Three Dynasties’plural but unified composite state structure,and its birth was signaled by the emergence of the Xia dynasty.At the time,kingship was related to the appellation“king”(王wang),but was not absolutely equated to it.On the one hand,whenever oracle bone and bronze inscriptions and textual records refer directly to“king(s),”the word refers to the Shang and Zhou kings;but on the other,some bronze inscriptions preserve the use of“king”to refer to the chieftains of smaller tribal states in remote areas.When a supreme dynastic ruler bore the appellation“king,”this indicated the kingly power of the royal house;but when the ruler of a small remote state called himself“king,”the word expressed rule over his state.The appellation“king”was used for these two different levels because the Chinese character“王”and the corresponding royal title originated in the shape of the battle axe that symbolized command of armies.The Xia dynasty was not China’s first state,for in the age of Yao,Shun and Yu numerous local states had organized themselves into tribal federations.Xia dynasty kingship,where the king was“common ruler of all under Heaven”(天下共主tianxia gongzhu)developed out of the power wielded by the hegemonic chieftains in the age of very large tribal states. 展开更多
关键词 KINGSHIP dynastic state composite state structure huaxia system of rites
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Red River barrier and Pleistocene climatic fluctuations shaped the genetic structure of Microhyla fissipes complex (Anura: Microhylidae) in southern China and Indochina 被引量:14
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作者 Zhi-Yong YUAN Chatmongkon SUWANNAPOOM +6 位作者 Fang YAN Nikolay A. POYARKOV JR Sang Ngoc NGUYEN Hong-man CHEN Siriwadee CHOMDEJ Robert W, MURPHY Jing CHE 《Current Zoology》 SCIE CAS CSCD 2016年第6期531-543,共13页
South China and Indochina host striking species diversity and endemism. Complex tectonic and climatic evolutions appear to be the main drivers of the biogeographic patterns. In this study, based on the geologic histor... South China and Indochina host striking species diversity and endemism. Complex tectonic and climatic evolutions appear to be the main drivers of the biogeographic patterns. In this study, based on the geologic history of this region, we test 2 hypotheses using the evolutionary history of Microhyla fissipes species complex. Using DNA sequence data from both mitochondrial and nuclear genes, we first test the hypothesis that the Red River is a barrier to gene flow and dispersal. Second, we test the hypothesis that Pleistocene climatic cycling affected the genetic structure and population history of these frogs. We detect 2 major genetic splits that associate with the Red River. Time estimation suggests that late Miocene tectonic movement associated with the Red River drove their diversification. Species distribution modeling (SDM) resolves significant ecolo- gical differences between sides of the Red River. Thus, ecological divergence also probably promoted and maintained the diversification. Genogeography, historical demography, and SDM associate patterns in southern China with climate changes of the last glacial maximum (LGM), but not Indochina. Differences in geography and climate between the 2 areas best explain the discovery. Responses to the Pleistocene glacial-interglacial cycling vary among species and regions. 展开更多
关键词 demographic histories ecological divergence genogeography LGM pigmy narrow-mouth frog
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Crustal and upper mantle structure and deep tectonic genesis of large earthquakes in North China 被引量:20
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作者 WANG ChunYong WU QingJu +2 位作者 DUAN YongHong WANG ZhiShuo LOU Hai 《Science China Earth Sciences》 SCIE EI CAS CSCD 2017年第5期821-857,共37页
From the 1960 s to 1970 s, North China has been hit by a series of large earthquakes. During the past half century,geophysicists have carried out numerous surveys of the crustal and upper mantle structure, and associa... From the 1960 s to 1970 s, North China has been hit by a series of large earthquakes. During the past half century,geophysicists have carried out numerous surveys of the crustal and upper mantle structure, and associated studies in North China.They have made significant progress on several key issues in the geosciences, such as the crustal and upper mantle structure and the seismogenic environment of strong earthquakes. Deep seismic profiling results indicate a complex tectonic setting in the strong earthquake areas of North China, where a listric normal fault and a low-angle detachment in the upper crust coexist with a high-angle deep fault passing through the lower crust to the Moho beneath the hypocenter. Seismic tomography images reveal that most of the large earthquakes occurred in the transition between the high-and low-velocity zones, and the Tangshan earthquake area is characterized by a low-velocity anomaly in the middle-lower crust. Comprehensive analysis of geophysical data identified that the deep seismogenic environment in the North China extensional tectonic region is generally characterized by a low-velocity anomalous belt beneath the hypocenter, inconsistency of the deep and shallow structures in the crust, a steep crustalal-scale fault,relative lower velocities in the uppermost mantle, and local Moho uplift, etc. This indicates that the lithospheric structure of North China has strong heterogeneities. Geologically, the North China region had been a stable craton named the North China Craton or in brief the NCC, containing crustal rocks as old as ~3.8 Ga. The present-day strong seismic activity and the lower velocity of the lower crust in the NCC are much different from typical stable cratons around the world. These findings provide significant evidence for the destruction of the NCC. Although deep seismic profiling and seismic tomography have greatly enhanced knowledge about the deep-seated structure and seismogenic environment, some fundamental issues still remain and require further work. 展开更多
关键词 North China Craton Crust and upper mantle structure Deep seismic sounding profile Deep seismic reflection profile Broadband seismic array Seismogenic environment
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