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991.
"一带一路"沿线国家或地区人才流动网络结构演化   总被引:3,自引:1,他引:3  
基于高等学校留学生流动数据,构建加权有向网络模型,对2000~2015年“一带一路”沿线国家或地区人才流动网络结构演化进行研究。主要结论如下:沿线人才流动网络规模迅速扩大,人才流动的数量和路径在迅速增加。沿线人才流动网络呈“由中向西,自南到北”的空间格局特征,中亚地区的留学生主要向西流向俄罗斯、乌克兰等国,东南亚和南亚地区的留学生主要向北流向中国内地。沿线人才流动网络分化为独联体社团、中国东盟社团、西亚北非社团、中东欧社团、南亚社团等5个社团。中国内地和俄罗斯处于沿线人才流动网络的核心位置,东南亚、西亚和东欧部分国家处于边缘地带。  相似文献   
992.
两形态类型织纹螺(Nassarius)的鉴定   总被引:1,自引:2,他引:1  
在整理广东珠海高栏岛潮下带的螺类样品时,发现两不同形态类型的织纹螺,一类型鉴定为西格织纹螺(Nassarius siquijorensis),另一类型与前者在内唇和外唇形态上存在明显差异但其他特征基本相同。比较了两类型个体的齿舌形态,并对选取的5个个体的COⅠ基因序列进行了研究。结果表明,两类型个体的齿舌形态基本一致,齿列数53—66排,中央齿上缘小齿8—12枚;COⅠ基因序列存在较大的变异,709bp的DNA片段上共有40个位点变异,其中38个变异位点为密码子第三位碱基,个体间的碱基差异在2—35bp之间;贝壳变异与DNA变异不存在关系,同类型的个体在DNA序列上差异较大,不同类型个体的差异却极小;在基于COⅠ基因序列构建的系统树中两类型的个体明显聚为一支。依据5条COⅠ基因核苷酸序列推导的氨基酸残基序列完全相同。齿舌形态和分子生物学证据都证实两种类型的个体同属于西格织纹螺。  相似文献   
993.
Thermal Anomalies and Earthquakes: Evidence from Wenchuan, China   总被引:1,自引:0,他引:1  
Earthquake prediction is a difficult problem in Earth sciences.Unsuccessful predictions one after another urged people to explore more synthetic and comprehensive methods for earthquake prediction.The Lithosphere-Atmosphere-Ionosphere(LAI)coupling theory pays great attention to the processes taking place within the near ground layer of atmosphere.It has achieved great results recently,and can enlighten us about the nature of an earthquake's precursor.Based on the NCEP reanalysis dataset,this paper attempts to track the anomalies of the surface's upward long wave radiation flux(ULWRF),the temperature at the depth of 10cm~20cm below ground surface layer(BGL)and the air temperature at 2 meters above ground surface(AIR)around the time of the strong Wenchuan earthquake.Thermal anomalies were observed before and after May 12,2008,the time of the Wenchuan earthquake.Perhaps the thermal anomaly that occurred prior to the earthquake can be taken as indicators of the earthquake,but in view of the complexity of the earthquake phenomena,using thermal anomaly as a precursor should be done with caution.  相似文献   
994.
The deteriorating water quality in the Taihu Lake Basin has attracted widespread attention for many years, and is correlated with a sharp increase in the quantity of pollutant discharge such as agricultural fertilizers and industrial wastewater. In this study, several factors were selected for evaluating and regionalizing the water environmental capacity by ArcGIS spatial analysis, including geomorphologic characteristics, water quality goals, water body accessibility, water-dilution channels, and current water quality. Then, the spatial optimization of agriculture and industry was adjusted through overlay analysis, based on the balance between industrial space and water environmental capacity. The results show that the water environmental capacity gradually decreases from the west to the east, in contrast, the pollution caused by industrial and agricultural clustering is distributes along Taihu Lake, Gehu Lake and urban districts. The analysis of the agricultural space focuses on optimizing key protected areas of the Taihu Lake Basin, and the shores of Gehu Lake, optimally adjusting the second protected areas of the Taihu Lake Basin, and generally adjusting the urban areas of Changzhou and Wuxi cities. The analysis of industrial space focuses on optimizing the downtowns of Changzhou and Wuxi cities, optimally adjusting key protected areas and second protected areas of the Taihu Lake Basin, and generally adjusting the south and southwest of Gehu Lake. Lastly, some schemes of industrial and agricultural layouts and policies for the direction of industrial and agricultural development were proposed, reflecting a correlation between industry and agriculture and the water environment.  相似文献   
995.
2012-06-28T5:00,四川省凉山彝族自治州宁南县矮子沟突降强暴雨,引发了特大灾害性泥石流,造成严重的人员伤亡和财产损失.此次泥石流是在长时间的前期降雨和短历时的强降雨共同作用下,从上游支沟坡面和两侧冲沟短时间内形成的,具有发展和运动历时短,规模中等而峰值流量大,泥石流和洪水交替作用等特点.严重的沟道堵塞和中下游松散物质的补充,使得泥石流的峰值流量是清水流量的3~4倍.  相似文献   
996.
高娟  吕娟 《陕西气象》2010,(3):46-48
太原基准站自动站地温变送器使用CAWS—BS01型,其工作原理是:CAWS—BS01受自动站采集器发出的控制信号触发,分别选通变送器的CH1-CHl2接口,使采集器可以对连接在12路接口上的传感器依此进行数据采集。CAWS—BS01接受控制信号触发,通过计数、延时、选通等逻辑控制电路,准确的将12路接口依此连通到采集器。  相似文献   
997.
The Sr, Nd and Pb isotopic compositions for the Kovdor phoscorite–carbonatite complex (PCC), Kola Peninsula, NW Russia, have been determined to characterize the mantle sources involved and to evaluate the relative contributions of a plume and subcontinental lithospheric mantle in the formation of the complex. The Kovdor PCC is a part of the Kovdor ultramafic–alkaline–carbonatite massif, and consists of six intrusions. The initial isotopic ratios of the analyzed samples, calculated at 380 Ma, display limited variations: εNd, + 2.0 to + 4.7; 87Sr/86Sr, 0.70319 to 0.70361 (εSr, − 12.2 to − 6.2); 206Pb/204Pb, 18.38 to 18.74; 207Pb/204Pb, 15.45 to 15.50; 208Pb/204Pb, 37.98 to 39.28. The Nd and Sr isotope data of the Kovdor PCC generally fit the patterns of the other phoscorites and carbonatites from the Kola Alkaline Province (KAP), but some data are slightly shifted from the mixing line defined as the Kola Carbonatite Line, having more radiogenic 87Sr/86Sr ratios. However, the less radiogenic Nd isotopic compositions and negative Δ7/4 values of Pb isotopes of the analyzed samples exclude crustal contamination, but imply the involvement of a metasomatized lithospheric mantle source. Isotopic variations indicate mixing of at least three distinct mantle components: FOZO-like primitive plume component, EMI-like enriched component and DMM-like depleted component. The isotopic nature of the EMI- and DMM-like mantle component observed in the Kovdor samples is considered to be inherited from metasomatized subcontinental lithospheric mantle. This supports the previous models invoking plume–lithosphere interaction to explain the origin of the Devonian alkaline carbonatite magmatism in the KAP.  相似文献   
998.
GRAPES-TCM业务试验结果分析   总被引:3,自引:2,他引:3  
朱振铎  端义宏  陈德辉 《气象》2007,33(7):44-54
应用数值模式GRAPES-TCM2.1(GT2.1)的升级版GRAPES-TCM2.6(GT2.6)对2005年西北太平洋及南海热带气旋路径进行了后报试验和性能检验。在检验预报路径时考察了平均距离误差、系统偏差、距离误差的地理分布和平均移速误差,并在总体检验的基础上,根据与热带气旋路径相关的重要因素(路径类型、强度、有无登陆过程以及有无移向或移速突变)进行了分类检验。结果表明,GT2.6表现出良好的预报性能,其对所有样本的24、48和72小时平均距离误差分别为135.8、230.7和336.0km,但前12小时距离误差较大(近100km)。用系统偏差订正GT2.6对转向类样本的预报路径可获得明显的改进。GT2.6对130°E以西区域特别是靠近我国东南沿海的热带气旋路径预报表现较好。GT2.6的总体平均预报移速在48小时内都比最佳路径移速偏快,初始的12小时内偏快最多(近1m·s^-1),在48小时后转为偏慢。GT2.6和GT2.1的前48小时路径预报性能的稳定性相当,总体误差特征相似,GT2.6对所有样本的48小时预报有显著改进,平均距离误差减小17km。初步分析表明,对GT2.6的改进应主要集中在数值预报初始场的改进方面,比如在初始化过程中采用较准确的涡旋分离方案、加入引导向量改进初始移动以及适当考虑加入非对称Bogus涡旋;扩大预报区域,并适当选取预报区域起始位置等。  相似文献   
999.
泉州盆地及其邻区地壳深部结构的探测与研究   总被引:1,自引:1,他引:1  
泉州盆地及其邻区地处我国大陆东南沿海地震带北段。通过对泉州盆地进行深地震反射探测,获得了该地区近地表至Moho面的精细几何结构及其深浅构造关系图像。这是该区第一条深地震反射探测剖面。分析结果表明,泉州盆地及其邻区地壳厚度变化在29.5~31.0km,由上地壳和下地壳组成。上地壳和下地壳又可以各分为2层。泉州盆地及其邻区近地表至浅部断裂发育,这些断裂向地壳深部最大延伸深度为6-12km,断裂的倾角随深度增加而逐渐变小,呈铲形正断层终止于上地壳上部反射界面C1,以上。在永安-晋江断裂带之下的上地壳下部和下地壳中,存在着切割上、下地壳分界面和Moho面的高倾角深断裂,尽管深浅部断裂构造不相连接,但由于深部存在深断裂,具有发生中强以上地震的深部构造环境。这一深地震反射探测成果的获得,使得泉州盆地及其邻区深部资料解释的可靠性和探测精度比以往显著提高;深浅部构造组合取得了统一的解释结果;地壳的分层和结构特征更为确切和精细;首次发现了上地壳的拉张性构造及铲式正断层组合特征。不仅有助于泉州及其邻区地震危险性的综合判定,而且对深化东南沿海地震带及台湾海峡深部动力学过程的认识具有重要意义。  相似文献   
1000.
At present, as the easily mining resources are being increasingly depleted, the exploitation of coal under buildings, water-bodies and railways is imminent for the sustainable production. Probability in-tegral method is a general method for mining subsidence in the coal system. Because of poor under-standing of mining subsidence for other sections, the authors suggest probability integral method for the study of coal mining under buildings, water-bodies and railways. Moreover, the calculation result of probability integral method should be corrected by numerical simulation method. Based on practical projects, the impact has been evaluated on the security of Xifeihe left embankment under coal mining. Combining with the results of probability integral method, we propose that the 600 m far from em-bankment is a good rationality. This article provides the basis for the rational exploitation of coal re-source which is a major practical problem under the premise of Water Infrastructure Security. Fur-thermore, it also can be served as a reference for the similar projects, such as mining Xiaolangdi res-ervoir area, mining Yuecheng reservoir and mining the major channels of Middle Route South to North Water Transfer.  相似文献   
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