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951.
印尼8.7级地震对川滇地区地震活动的影响 总被引:2,自引:2,他引:0
对1900年以来印尼爪哇海沟地区发生的8.0级以上地震与川滇地区5.0级以上地震作了统计、对比和分析,并利用跨断层位移流动观测资料,对2004年12月26日印尼苏门答腊西部海域8.7级地震前后,川滇地区的区域构造活动变化进行了分析研究,初步认为:印尼8.7级地震后,川滇地区1~3年内发生7.0级以上地震的可能性不大;1~2年内发生6~7级地震的可能性较大;1年内发生5级以上地震至少两次;纬度27°以南地区可能是未来1年内发震的危险地区,地球自转速度减慢,可能预示川滇地区强震活跃期即将到来。 相似文献
952.
Fe^2+ acted as an accessorial factor for many cellular enzymatic reactions is very important for seaweed growth and development, but the Fe^2+ requirement in nori had not been seen. Porphyra yezoensis cells were separated enzymatically and cultured in a series of sterilized seawater media containing various concentrations of Fe^2+. The growth development and cell were investigated in this work. Through this experiment, two biologically-meant concentration scales were found, one is low concentrations, 12.1-102.1μg/L, 10-100 times than that in seawater, favoring the development of isolated cells of Porphyra and the other was high concentrations, more than 10mg/L inhibiting the cell growth, leading to the deformity and shrinkage of the cells. At the concentration of 50 mg/L, the cells stopped growing and died eventually. 相似文献
953.
DAI Dejun WANG Wei QIAO Fangli YUAN Yeli 《中国海洋大学学报(英文版)》2007,6(4):345-348
Laboratory experiments and field observations show that the equilibrium range of wind wave spectra presents a – 4 power law when it is scaled properly. This feature has been attributed to energy balance in spectral space by many researchers. In this paper we point out that white noise on an oscillation system can also lead to a similar inverse power law in the corresponding displacement spectrum, implying that the – 4 power law for the equilibrium range of wind wave spectra may probably only reflect the randomicity of the wind waves rather than any other dynamical processes in physical space. This explanation may shed light on the mechanism of other physical processes with spectra also showing an inverse power law, such as isotropic turbulence, internal waves, etc. 相似文献
954.
Jin-Bo Feng Yong-Feng Huang Zi-Gao Dai Tan Lu Department of Astronomy Nanjing University Nanjing LCRHEA Institute for High-Energy Physics Chinese Academy of Sciences Beijing 《中国天文和天体物理学报》2002,2(6)
In previous works, a generic dynamical model has been suggested by Huang et al., which is shown to be correct for both adiabatic and radiative blast-waves, in both ultra-relativistic and non-relativistic phases. In deriving their equations, Huang et al. have assumed that the radiative efficiency of the fireball is constant. They then applied their model directly to realistic cases where the radiative efficiency evolves with time. In this paper, we abandon the above assumption and re-derive a more accurate dynamical equation for gamma-ray burst remnants. Numerical results show that the model presented by Huang et al. is accurate enough in general cases. 相似文献
955.
This study deals with the hydrochemical state and management measures for the intermediate culturepond for Chinese prawn (Penaeus orientalis) juveniles. The test result showed that the intermediate cultureof Chinese prawn juvenile can be advanced to around March 20 in the Shanghai area if they are culturedin ponds in simple greenhouses of plastic knitting cloth.The density of juveniles introduced was about35 million per hectare, survival was up to 55%. 相似文献
956.
在实行“两个转变”中,地勘单位的设备管理要适应市场经济需要,紧密结合地勘单位在开发新产品、新工艺以及生产装备更新的需求,实现管理科学化、现代化、集约化,步入良性循环。 相似文献
957.
遥感影像识别方法是破坏性地震震后地质灾害快速、准确获取的重要方法之一,传统的遥感影像识别方法主要以人工目视识别方法和半自动识别方法为主,需投入大量的人力和时间。针对破坏性地震震后地质灾害解译时间长、投入人力多等问题,以2017年8月8日四川九寨沟7.0级地震震后高分辨率无人机遥感影像为研究样本,提出基于深度学习网络的地震地质灾害识别方法。首先结合震后遥感影像解译资料和现场调查资料,提取九寨沟地震地质灾害无人机遥感影像特征,并构建研究区地震地质灾害解译指标和分类数据集;然后采用DeepLabv3+网络结构及softmax损失函数,建立基于深度学习网络的地震地质灾害遥感影像图像语义分割模型方法;最后采用半监督学习方法进行结果验证。研究结果表明,基于深度学习网络的地震地质灾害识别方法可有效识别九寨沟地震地质灾害分布信息,整体分类识别准确率为94.22%,F1分数值为0.77,结果具有较好的一致性和准确性,可提升地震现场灾情获取和重点地震隐患识别等工作效率及服务能力。 相似文献
958.
959.
Modeling net primary productivity of the terrestrial ecosystem in China from 1961 to 2005简 总被引:6,自引:2,他引:4
Net primary productivity (NPP) is the structure and function of the ecosystem. NPP can most important index that represents the be simulated by dynamic global vegetation models (DGVM), which are designed to represent vegetation dynamics relative to environ- mental change. This study simulated the NPP of China's ecosystems based on the DGVM Integrated Biosphere Simulator (IBIS) with data on climate, soil, and topography. The appli- cability of IBIS in the NPP simulation of China's terrestrial ecosystems was verified first. Comparison with other relevant studies indicates that the range and mean value of simula- tions are generally within the limits of observations; the overall pattern and total annual NPP are close to the simulations conducted with other models. The simulations are also close to the NPP estimations based on remote sensing. Validation proved that IBIS can be utilized in the large-scale simulation of NPP in China's natural ecosystem. We then simulated NPP with climate change data from 1961 to 2005, when warming was particularly striking. The following are the results of the simulation. (1) Total NPP varied from 3.61 GtC/yr to 4.24 GtC/yr in the past 45 years and exhibited minimal significant linear increase or decrease. (2) Regional differences in the increase or decrease in NPP were large but exhibited an insignificant overall linear trend. NPP declined in most parts of eastern and central China, especially in the Loess Plateau. (3) Similar to the fluctuation law of annual NPP, seasonal NPP also displayed an insignificant increase or decrease; the trend line was within the general level. (4) The re- gional differences in seasonal NPP changes were large. NPP declined in spring, summer, and autumn in the Loess Plateau but increased in most parts of the Tibetan Plateau. 相似文献
960.