毛乌素沙地锦鸡儿（Caragana）根系微域细菌群落多样性特征     

周子渊  于明含  丁国栋  高广磊  何莹莹 《中国沙漠》2020,40(4):128-137

基于16S rRNA高通量基因测序技术，对毛乌素沙地小叶锦鸡儿（Caragana microphylla)、柠条锦鸡儿（Caragana korshinskii）根系微域（即根系、根际土、根区土、灌丛间空白土）间的细菌群落多样性和结构差异性进行表征。本研究对各根系微域间细菌群落的Alpha多样性指数进行了单因素方差分析以及基于OTU水平的PCA分析，探究其在根系微域间Alpha和Beta多样性的层级变化，证实了有关植物根系微域生态位分化的报道，并发现锦鸡儿属植物根系微域间细菌群落的多样性和结构组成随着4个微域类型由外及内呈现出显著的层级差异性（P<0.05）。通过对优势细菌群组的结构组成分析，发现锦鸡儿属植物对特定细菌群组具有显著的向根系内筛选富集的作用（P<0.05）。这种植物通过根系微域对特定细菌群组的逐级筛选富集作用，是导致锦鸡儿属植物灌丛下不同生态位间细菌群落结构和组成发生层级变异的主要原因。  相似文献   

Model tests on XCC-piled embankment under dynamic train load of high-speed railways     

Tingting Niu  Hanlong Liu  Xuanming Ding  Changjie Zheng 《地震工程与工程振动(英文版)》2018,17(3):581-594

Piled embankments, which offer many advantages, are increasingly popular in construction of high-speed railways in China. Although the performance of piled embankment under static loading is well-known, the behavior under the dynamic train load of a high-speed railway is not yet understood. In light of this, a heavily instrumented piled embankment model was set up, and a model test was carried out, in which a servo-hydraulic actuator outputting M-shaped waves was adopted to simulate the process of a running train. Earth pressure, settlement, strain in the geogrid and pile and excess pore water pressure were measured. The results show that the soil arching height under the dynamic train load of a high-speed railway is shorter than under static loading. The growth trend for accumulated settlement slowed down after long-term vibration although there was still a tendency for it to increase. Accumulated geogrid strain has an increasing tendency after long-term vibration. The closer the embankment edge, the greater the geogrid strain over the subsoil. Strains in the pile were smaller under dynamic train loads, and their distribution was different from that under static loading. At the same elevation, excess pore water pressure under the track slab was greater than that under the embankment shoulder.  相似文献   

南海东北部内潮的模态结构和传播     

刘倩  谢晓辉  尚晓东  陈桂英  汪宏 《海洋学报(英文版)》2019,38(9):12-23

The evolution of energy, energy flux and modal structure of the internal tides(ITs) in the northeastern South China Sea is examined using the measurements at two moorings along a cross-slope section from the deep continental slope to the shallow continental shelf. The energy of both diurnal and semidiurnal ITs clearly shows a～14-day spring-neap cycle, but their phases lag that of barotropic tides, indicating that ITs are not generated on the continental slope. Observations of internal tidal energy flux suggest that they may be generated at the Luzon Strait and propagate west-northwest to the continental slope in the northwestern SCS. Because the continental slope is critical-supercritical with respect to diurnal ITs, about 4.6 kJ/m~2 of the incident energy and 8.7 kW/m of energy flux of diurnal ITs are reduced from the continental slope to the continental shelf. In contrast, the semidiurnal internal tides enter the shelf because of the sub-critical topography with respect to semidiurnal ITs.From the continental slope to the shelf, the vertical structure of diurnal ITs shows significant variation, with dominant Mode 1 on the deep slope and dominant higher modes on the shelf. On the contrary, the vertical structure of the semidiurnal ITs is stable, with dominant Mode 1.  相似文献   

Formation of the Neoproterozoic Rifting Depression Groups of the Tarim Basin and its Hydrocarbon Potential: Responded to the Initial Opening of the Proto-Tethy Ocean     

HE Bizhu  JIAO Cunli  LIU Ruohan  HUANG Taizhu  CAI Zhihui  CAO Zicheng  YUN Xiaorui  Lan Mingjie  JIANG Zhongzheng  ZHU Ding  YANG Yujie  CUI Junwen  HAO Guangming 《《地质学报》英文版》2020,94(Z1):16-16

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载人潜水器运行管理机制探析          下载免费PDF全文

齐海滨  李德威  刘保华  杨雷  刘晓辉 《海洋开发与管理》2019,36(7):3-7

为了探索深海,不同类型的深海运载装备得以成功开发,并应用于深海科学、资源勘探开发、工程保障及战略安全等不同领域。深海运载装备可以分为载人潜水器(HOV)、遥控深潜器(ROV)、自治式深潜器(AUV)及混合型深潜器,其中以载人潜水器为代表的高技术装备群成为建设海洋强国的重要保障力量。文章对美国"阿尔文"号、俄罗斯"和平I"号和"和平II"号、日本"深海6500"号、法国"鹦鹉螺"号、中国"蛟龙"号载人潜水器运行管理机制进行了阐述,综合比较其优缺点,提出了建立职业化运行保障队伍、优化作业流程,创新组织结构、探索多型潜水器海上作业模式等运行管理机制构架的建议。  相似文献   

Asymmetry in oceanic crustal structure of the South China Sea basin and its implications on mantle geodynamics     

Fan Zhang  Xubo Zhang  Weiwei Ding  Tingting Wang  Jian Zhu 《International Geology Review》2020,62(7-8):840-858

ABSTRACT

We investigated the oceanic crustal structure and lithospheric dynamics of the South China Sea (SCS) basin through a comprehensive analysis of residual gravity anomaly and bathymetry combined with seismic constraints and interpretation from geodynamic modelling. We first calculated the residual mantle Bouguer anomaly (RMBA) of the oceanic crustal regions of the SCS by removing from free-air gravity anomaly the predicted gravitational attractions of water-sediment, sediment-crust, and crust-mantle interfaces, as well as the effects of lithospheric plate cooling, using the latest crustal age constraints including IODP Expedition 349 and recent deep-tow magnetic surveys. We then calculated models of the gravity-derived crustal thickness and calibrated them using the available seismic refraction profiles of the SCS. The gravity-derived crustal thickness models correlate positively with seismically determined crustal thickness values. Our analysis revealed that the isochron-averaged RMBA are consistently more negative over the northern flank of the SCS basin than the southern conjugate for magnetic anomaly chrons C8n (~25.18 Ma) to C5Dn (~17.38 Ma), implying warmer mantle and/or thicker crust over much of the northern flank. Computational geodynamic modelling yielded the following interpretations: (1) Models of asymmetric and variable spreading rates based on the relatively high-resolution deep-tow magnetic analysis would predict alternating thicker and thinner crust at the northern flank than the southern conjugate, which is inconsistent with the observed systematically thicker crust on the northern flank. (2) Models of episodic southward ridge jumps could reproduce the observed N-S asymmetry, but only for crustal age of 23.6–20 Ma. (3) Southward migration of the SCS ridge axis would predict slightly thinner crust at the northern flank, which is inconsistent with the observations. (4) Models of higher mantle temperatures of up to 25–50°C or >2% less depleted mantle sources on the northern flank could produce large enough anomalies to explain the observed N-S asymmetries.  相似文献   

徕卡RTC360三维激光扫描仪在竣工测量中的应用     

汪晓慧  吴晓培 《测绘通报》2019,(10):150-154,159

徕卡RTC360不仅操作简单、扫描速度快，而且非常智能。可以实时跟踪计算两个连续站点间的相对位置，点云实时预拼接。后期搭配Register360智能拼接软件，点云智能拼接处理，无需人工干预，简单高效。  相似文献   

基于高分影像的松嫩低平原地区生态环境问题解析——以黑龙江省肇源县为例     

丁宇雪  毛龙  周向斌  初炜钰 《吉林大学学报(地球科学版)》2020,50(4):1240-1248

基于高分辨率卫星影像数据，利用遥感、GIS技术获取黑龙江省肇源县内自然资源与生态地质环境各因子分布现状数据，其中：耕地2 541.75 km²、林地161.88 km²、草地349.00 km²、河流128.05 km²、湖泊215.80 km²、沼泽109.17 km²、其他水域84.65 km²、建设用地191.25 km²、未利用地329.94 km²；湿地1 334.54 km²、荒漠化土地775.47 km²。利用地类覆盖率、人均占有量以及景观指数（破碎度指数、平均斑块分形指数、分形维数、多样性指数、均匀度指数）量化分析后，得出两类生态地质环境因子中湿地资源尤其是自然湿地受人类活动干扰程度较大、荒漠化土地受人类活动干扰程度较小的结论。并选取老山村等典型地区进行了多期次遥感动态监测及野外核查，揭示了松嫩低平原典型地区目前存在的湿地退化、土地荒漠化等生态地质环境问题。  相似文献   

丽江-小金河断裂全新世滑动速率研究     

郜宇  丁锐  张世民  任俊杰 《震灾防御技术》2019,14(3):617-627

丽江-小金河断裂与锦屏山断裂共同控制着青藏高原东南边界，研究该断裂的滑动速率有助于理解青藏高原东南缘区域变形模式。本文通过高分辨率遥感影像解译与野外地质调查，发现该断裂错断了一系列河流阶地与洪积扇，且以左旋走滑为主兼具倾滑分量。通过无人机断错地貌测量与碳同位素断代，获得红星-尖山营断裂段全新世左旋走滑速率为（3.32±0.22）mm/a，垂直滑动速率为（0.35±0.02）mm/a；汝南-南溪断裂段北支全新世左旋走滑速率为（2.37±0.20）mm/a。  相似文献   

Study on the Natural Mineral Water Resource Bearing Capacity and its Driving Factors in Fusong County,Changbai Mountain Area,Jilin Province of China     

Jianmin Bian  Sun  Xiaoqing  Zhang  Bingjing  Zhang  Zhenzhen  Ding  Fei  Wang  Yu 《Water Resources》2019,46(3):332-343

Water Resources - In order to maintain the sustainable exploitation of the natural mineral water resources in Changbai Mountain Area with the continuously increasing exploitation intensity,...  相似文献