城镇化水平测定方法构建与案例   总被引：1，自引：0，他引：1  

陈晓倩  张全景  代合治  于伟 《地域研究与开发》2011,30(4):76-80

城镇化水平作为衡量一个国家和地区城镇化的指标,其测定方法还不甚完善,对其进行研究成为科学评价我国城镇化水平的一个重要课题。城镇与乡村最直观的区别在于人口的集聚程度、人口的职业构成、土地的利用方式,因此,在既有城镇地域界定标准的基础上,选择人口密度、非农业人口比重、建成区面积比重、人均耕地面积等指标作为判断不同政区是否成为城镇地域的基本指标。通过层层设置临界值,合理地界定了城镇地域范围,并核定了城镇人口,为科学计算城镇化水平提供了依据。以曲阜市为实例,对上述标准进行检验,结果表明,这种城乡划分标准合理,结果符合实际,同时计算简便,利于应用。  相似文献   

金沙江奔子栏-达日河段大型泥石流堆积扇的成因机制   总被引：1，自引：0，他引：1  

陈剑  崔之久  戴福初  许冲 《山地学报》2011,29(3)

金沙江上游奔子栏-达日河段属横断山区的干热河谷地带,河谷沿岸大型古泥石流堆积扇广泛发育,其成因却一直没有得到很好的研究.对该区瓦卡大型古泥石流堆积物进行了沉积结构、粒度、地球化学和孢粉等分析,揭示了泥石流的沉积环境及其形成过程.通过粗颗粒石英的光释光单片再生法(SAR)测年研究,获得金沙江上游奔子栏-达日河段古泥石流大规模暴发的年代为12 600～4 500 a BP.丰富的风化碎屑物源、陡峻的地形及雨季降水集中是该区古泥石流形成的主要原因.全新世早期青藏高原东南缘受西南季风加强的影响,气候趋于暖湿,季节性暴雨增加.金沙江上游干热河谷区大型泥石流堆积扇的发育年代暗示其是全新世早期西南季风加强作用下的地貌响应.从地质灾害防治的角度,由于现代气候因素导致泥石流灾害的频度和规模较小,预防该区地质灾害的重点应是防止人工砍伐树木和不合理的人工切坡导致对地表环境的破坏加剧.  相似文献   

Constraining the cosmological parameters and transition redshift with gamma-ray bursts and supernovae     

F. Y. Wang  Z. G. Dai 《Monthly notices of the Royal Astronomical Society》2006,368(1):371-378

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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  

焦青  范国胜  戴梁焕 《大地测量与地球动力学》2005,25(3):100-104

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   

The influence of Fe^2＋ on growth and development of cells enzymatically isolated from Porphyra yezoensis blades     

沈颂东  戴继勋 《中国海洋湖沼学报》2005,23(1):48-53

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   

The Equilibrium Range of Wind Wave Spectra： an Explanation Based on White Noise     

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   

Dynamical Evolution of Gamma-Ray Burst Remnants with Evolving Radiative Efficiency     

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   

HYDROCHEMICAL STATE OF INTERMEDIATE CULTURE POND FOR CHINESE PRAWN JUVENILES     

臧维玲  张建达  戴习林  朱正国  徐桂荣  宋林华  李士华 《中国海洋湖沼学报》1996,14(1):41-46

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   

地勘单位实行两个转变中的设备管理     

戴前华 《南方国土资源》1997,(3)

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   

基于深度学习网络的地震地质灾害识别研究     

肖本夫  吴今生  毛利  顾铁  梁远玲  代友林 《震灾防御技术》2021,16(4):617-624

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