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941.
在中国第28次南极科学考察期间,利用“雪龙号”科考船载SIMRAD EK500(38kHz)科学渔探仪对南极半岛附近海域的南极大磷虾资源量进行了调查。原始声学数据经过信噪比估算和背景噪声剔除数据后处理方法剔除背景噪声以及手动剔除表面混响、海底反射和坏数据之后,在200 m以浅水层中,以1n mile间隔进行积分,并应用Matlab软件编程对积分结果进行后处理,得出调查海域中南极大磷虾的资源分布情况。结果表明:(1)“雪龙号”的平均噪声功率值为-146.47dB re 1W;(2)空白水体的噪声平均剔除百分比为88.3%;(3)调查区域内的南极大磷虾平均密度为27.30 g·m-2(62.95 ind·m-2)。 相似文献
942.
利用2003-2012年的地面填图和探空资料,统计常用对流参数满足指定阈值条件时广西6个探空站出现雷暴天气的概率(简称"雷暴概率")。统计结果表明:整层比湿积分(IQ)、K指数(KI)和抬升指数(LI)与雷暴概率有显著的线性关系,当IQ、KI增大,或LI减小时,雷暴概率增大。对流有效位能(CAPE)在0-200J·kg-1之间增长时雷暴概率迅速增大,但超过200J·kg-1后雷暴概率增大不明显。根据统计结果,选取IQ、KI和LI作为预报因子,CAPE作为消空因子,定义了一个适用于广西雷暴天气的经验预报指标。用2013年资料做试报检验,结果表明该指标对6小时内的雷暴天气有较好的预报能力。 相似文献
943.
Multi-Method Study on Seismogenic Structure of Rushan Earthquake Sequence in Shandong Province,China
Izvestiya, Physics of the Solid Earth - The ML 3.8 earthquake occurred in Rushan County On October 1, 2013, Shandong Province, eastern China. After this event, there are already more than... 相似文献
944.
LA-MC-ICP-MS锆石Hf同位素的分析方法及地质应用 总被引:68,自引:111,他引:68
本研究利用Thermo Finngan Neptune型多接收等离子质谱和Newwave UP213 激光剥蚀系统对两个国际锆石标准和一个实验室锆石标准进行了系统的测定.测得的TEMORA、GJ1和FM02锆石标准的176Hf/177Hf比值分别为0.282700±64(2SD,N=22),0.282008±25(2SD,N=26)和0.282967±44(2SD,N=27),该结果在误差范围内与文献报道值完全一致.采用不同的剥蚀直径对FM02锆石标准进行了对比测定,结果在误差范围内是一致的.从分析结果来看,GJ1和FM02的Hf同位素比值变化范围较小,是Hf同位素LA-MC-ICP-MS测试的理想标准锆石.文中还对四个不同地区的锆石Hf同位素进行了测定,结合前人研究,对其成因和物质来源进行了初步探讨. 相似文献
945.
辽东半岛韧性剪切带可分为两种类型,一类为低角度逆冲推覆型,多为北东—南西向或北北东—南南西走向,大致分布于辽东半岛东南边缘;另一类为高角度近水平剪切滑动型,多分布于半岛内部的a线理及运动学特征指示这些剪切带的总体应力场这由南东东向北西西推覆、挤压。剪切带的形成时间大多在中生代末期。辽东半岛金矿大多与这次韧性剪切活动有关,由剪切活动产生的一些韧-脆性的变形带很可能即是环太平洋成矿作用的容矿构造。 相似文献
946.
THE INDUSTRIAL STRUCTURE AND DISTRIBUTION OF THE BOHAI-YELLOW SEA RIMLAND OF CHINA IN THE 1990S 总被引:2,自引:1,他引:1
The Bohai-Yellow Sea Rimland (BYSR) is situated along the coast of theBohai Sea and the Yellow Sea in the northeast of China, covering Liaoning, Hebei, and Shandong provinces, and Tianjin and Beijing municipalities. It has a land area of 491,000 square kilometers, 5.1 percent of the country's total, and a population of 196 million, 17.9 percent of the total. Theregion is not only the political and cultural center, but also the most important economic center in North China. This paper analyses current status and major problems of industrial structure and distribution of BYSR. According to the national plan, the main goal in the coming decade is: by constantly improving economic structure, economic quality and efficiency, to double the gross national product(GNP), and to raise living standards to a satisfactory level. To realize this goal, agriculture, energy, transportation, some important raw material of industries, and infrastructure should be strengthened, and the engineering industry be improved to c 相似文献
947.
948.
Developmental characteristics of aeolian dunes and environmental changes in the adjoining region of Puruogangri ice sheet, North Tibetan Plateau 总被引:2,自引:0,他引:2
Weimin Zhang Tao Wang Jianjun Qu Xiaozhe Li Rupin Zou Bao Yang 《Environmental Geology》2005,48(1):15-24
A large area of moraine sediments and cryogenic weathering products, formed by glacial action and a cold environment, are the main source of aeolian sand in the high and cold region of the Qinghai–Tibetan Plateau in China. The evolution of aeolian dunes is closely related to the periglacial environment. Owing to the freezing of dune-land surfaces, the evolution of sand dunes is dominated by expanding dune bases and vertical accretion, thereby forming large barchan dunes. The migration rates of these large barchan dunes are very slow at an average rate of 1.7–0.7 cm·a–1. The temperature mainly controls the environmental changes in the adjoining region of Puruogangri ice sheet. The 14C dating of humus layers in the studied area of the sand dune are 10,780±130, 9,549±130, 8,320±110, 7,450±100, 5,970±95, 5,330±90, 4,420±80, 3,460±80, 2,280±70, 980±70 aBP, respectively. The regions high temperature rising up during summer from the southwest monsoon intensity might be an important factor. As long as both water and temperature conditions are suitable, the plants will grow well, sand dunes will be stabilized, forming humus layers. Otherwise, sand dunes are bare and re-activate. 相似文献
949.
The comparative observations of the tidal gravity in Three Gorges reservoir area, recorded with the LCR-ET20 gravimeter from Institute of Geodesy and Geophysics, Chinese Academy of Sciences and the DZW-9 gravimeter from Institute of Seismology, China Earthquake Administration, are introduced. High-accuracy tidal gravity pa-rameters in this area are obtained, and the scale factor of the DZW-9 gravimeter is also estimated at a value of ?(756.06±0.05)×10?8 m?s?2V?1. The observed residuals of the corresponding instruments are investigated. Nu-merical results indicate that the long-term drift of the DZW-9 gravimeter appears a linear characteristic, and the observed accuracy is of the same order comparing with that of the LCR-ET20 gravimeter. The results given in the paper can provide with an effective reference model of the tidal gravity correction to the ground based and space geodesy. 相似文献
950.
Two parameterization schemes for vertical eddy diffusivity were utilized to investigate their impacts on both the daily and monthly mean concentrations of ozone and NOy, which are the major fractions of the sum of all reactive nitrogen species, i.e., NOy=NO+NO2+HNO3+PAN. Simulations indicate that great changes in the vertical diffusivity usually occur within the planetary boundary layer (PBL). Daily and monthly mean concentrations of NOy are much more sensitive to changes in the vertical diffusivity than those of ozone and ozone and NOy levels only at or in (relatively) clean sites and areas, where long-range transport plays a crucial role, display roughly equivalent sensitivity. The results strongly suggest that a widely-accepted parameterization scheme be selected and the refinement of the model's vertical resolution in the PBL be required, even for regional and long-term studies, and ozone only being examined in an effort to judge the model's performance be unreliable, and NOy be included for model evaluations. 相似文献