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141.
142.
四川省拐卖儿童犯罪的时空演变过程及影响因素分析 总被引:1,自引:1,他引:0
拐卖儿童犯罪给受害者带来身心创伤、给家庭带来巨大悲痛和长期困扰,已成为社会和学界关注的焦点问题。该领域犯罪地理学视角的研究兴起较晚,且主要侧重宏观整体分析,当前亟需聚焦高发源地和重点人群作精细解析。为此,论文针对中国拐卖犯罪重灾源区四川省,综合运用数理统计、空间分析、文本分析、案例分析等方法探究四川省拐卖儿童犯罪的时空演变过程与影响因素。研究发现:① 数量上,被拐男童明显多于女童,被拐儿童主要来自乡村,虽呈现1~6岁和14~17岁的“双峰”型特征,但整体趋向低龄化。② 时间上,犯罪年际分布大致呈倒“V”型波动态势,高发期为1981—2000年;犯罪年内分布集中于夏半年,周内分布周末高发,日期分布每月1日的被拐儿童数量最多。③ 空间上,存在一个被拐高发区和多个被拐次高发区;县域尺度上的犯罪格局呈现“高—高”和“低—低”聚集;随着时间的变化,拐出热点区不断向南部和东部蔓延;宏观贩运路径上,向中东部地区分散拐入,华北和华南是重点拐入的“南北两汇”。④ 对1981—2000年犯罪高发期的原因解析发现,受教育水平与城乡收入差距是影响拐卖儿童犯罪的主导因素。 相似文献
143.
高师地理师范专业的隐性课程体系弱化是人才培养课程体系中主要问题之一。当前高师地理师范专业隐性课程普遍存在比重偏低、综合性较弱、碎片化明显、特色不突出、动态性不足的问题。要实现隐性课程在课程体系中的深度融合,可从隐性课程特性与地理学特性角度对隐性课程体系进行重构,调整结构,优化比重,实现隐性课程的协调化;协同整合,整体推进,形成隐性课程的综合化;重构融合,完善体系,实现隐性课程的系统化;凝练内涵,突出特色,形成隐性课程内容的差异化;更新调整,继承吸收,实现隐性课程内涵的动态化。 相似文献
144.
Altimeter data and output from the HYbrid Coordinate Ocean Model global assimilation run are used to study the seasonal variation
of eddy shedding from the Kuroshio intrusion in the Luzon Strait. The results suggest that most eddy shedding events occur
from December through March, and no eddy shedding event occurs in June, September, or October. About a month before eddy shedding,
the Kuroshio intrusion extends into the South China Sea and a closed anticyclonic eddy appears inside the Kuroshio loop which
then detaches from the Kuroshio intrusion. Anticyclonic eddies detached from December through February move westward at a
speed of about 0.1 m s−1 after shedding, whereas eddies detached in other months either stay at the place of origin or move westward at a very slow
speed (less than 0.06 m s−1). The HYCOM outputs and QuikSCAT wind data clearly show that the seasonal variation of eddy shedding is influenced by the
monsoon winds. A comparison between eddy volume and integrated Ekman transport indicates that, once the integrated Ekman transport
exceeds 2 × 1012 m3 (which roughly corresponds to the volume of an eddy), the Kuroshio intrusion expands and an eddy shedding event occurs within
1 month. We infer that the Ekman drift of the northeasterly monsoon pushes the Kuroshio intrusion into the SCS, creates a
net westward transport into the Strait, and leads to an eddy detachment from the Kuroshio. 相似文献
145.
Roles of Biogeochemical Processes in the Oceanic Carbon Cycle Described with a Simple Coupled Physical-Biogeochemical Model 总被引:1,自引:0,他引:1
Masahiko?FujiiEmail author Motoyoshi?Ikeda Yasuhiro?Yamanaka 《Journal of Oceanography》2005,61(5):803-815
To evaluate the contribution of biogeochemical processes to the oceanic carbon cycle and to calculate the ratio of calcium
carbonate to organic carbon downward export, we have incorporated biological and alkalinity pumps in the yoked high-latitude
exchange/interior diffusion-advection (YOLDA) model. The biogeochemical processes are represented by four parameters. The
values of the parameters are tuned so that the model can reproduce the observed phosphate and alkalinity distributions in
each oceanic region. The sensitivity of the model to the biogeochemical parameters shows that biological production rates
in the euphotic zone and decomposition depths of particulate matters significantly influence horizontal and vertical distributions
of biogeochemical substances. The modeled vertical fluxes of particulate organic phosphorus and calcium carbonate are converted
to vertical carbon fluxes by the biological pump and the alkalinity pump, respectively. The downward carbon flux from the
surface layer to the deep layer in the entire region is estimated to be 3.36 PgC/yr, which consists of 2.93 PgC/yr from the
biological pump and 0.43 PgC/yr from the alkalinity pump, which is consistent with previous studies. The modeled rain ratio
is higher with depth and higher in the Pacific and Indian Oceans than in the Atlantic Ocean. The global rain ratio at the
surface layer is calculated to be 0.14 to 0.15. This value lies between the lower and higher ends of the previous estimates,
which range widely from 0.05 to 0.25. This study indicates that the rain ratio is unlikely to be higher than 0.15, at least
in the surface waters. 相似文献
146.
The amount of methane leaked from deep sea cold seeps is enormous and potentially affects the global warming,ocean acidification and global carbon cycle. It is of great significance to study the methane bubble movement and dissolution process in the water column and its output to the atmosphere. Methane bubbles produce strong acoustic impedance in water bodies, and bubble strings released from deep sea cold seeps are called "gas flares"which expressed as flame-like strong backscatter in the water column. We characterized the morphology and movement of methane bubbles released into the water using multibeam water column data at two cold seeps. The result shows that methane at site I reached 920 m water depth without passing through the top of the gas hydrate stability zone(GHSZ, 850 m), while methane bubbles at site II passed through the top of the GHSZ(597 m) and entered the non-GHSZ(above 550 m). By applying two methods on the multibeam data, the bubble rising velocity in the water column at sites I and II were estimated to be 9.6 cm/s and 24 cm/s, respectively. Bubble velocity is positively associated with water depth which is inferred to be resulted from decrease of bubble size during methane ascending in the water. Combined with numerical simulation, we concluded that formation of gas hydrate shells plays an important role in helping methane bubbles entering the upper water bodies, while other factors, including water depth, bubble velocity, initial kinetic energy and bubble size, also influence the bubble residence time in the water and the possibility of methane entering the atmosphere. We estimate that methane gas flux at these two sites is 0.4×10~6–87.6×10~6 mol/a which is extremely small compared to the total amount of methane in the ocean body, however, methane leakage might exert significant impact on the ocean acidification considering the widespread distributed cold seeps. In addition, although methane entering the atmosphere is not observed, further research is still needed to understand its potential impact on increasing methane concentration in the surface seawater and gas-water interface methane exchange rate, which consequently increase the greenhouse effect. 相似文献
147.
文章于2018年1月(冬季)、4月(春季)、7月(夏季)、10月(秋季)对我国考洲洋海域海水中的溶解氧(DO)、化学需氧量(COD)、无机氮(DIN)、活性磷酸盐(DIP)4个主要海水水质因子进行了综合调查。结果表明,4个水质因子DIP、DIN、COD、DO的平均浓度由高到低的季节变化分别为:冬季(0.058 mg/L)、春季(0.046 mg/L)、夏季(0.009 mg/L)、秋季(0.006 mg/L);冬季(0.465 mg/L)、春季(0.171 mg/L)、夏季(0.064 mg/L)、秋季(0.040 mg/L);夏季(1.57 mg/L)、冬季(1.26 mg/L)、秋季(1.22 mg/L)、春季(0.89 mg/L);冬季(11.70 mg/L)、夏季(7.41 mg/L)、秋季(7.36 mg/L)、春季(7.18 mg/L)。评价结果显示,春季和冬季主要超标因子为DIP和DIN,夏季超标因子为DIP,秋季水质因子均满足要求。同时,本研究利用单因子标准指数法、富营养化指数法和有机污染评价指数法对考洲洋地区水质状况进行评价并对其进行初步比较和分析,结果表明,3种方法在季节性变化上的评价结果基本一致(由高到低均为:冬季、春季、夏季、秋季),然而,同一季节不同评价方法的超标站位比例不同(单因子指数法:冬季占100%,春季占80%,夏季占10%,秋季则无;富营养化指数法:冬季占90%,春季占70%,夏季和秋季均为无;有机污染指数评价法:冬季和春季均占80%,夏季和秋季均为无),比较分析表明,3种评价方法具有不同的评价作用和适用性。 相似文献
148.
Xavier?LurtonEmail authorView authors OrcID profile Dimitrios?Eleftherakis Jean-Marie?Augustin 《Marine Geophysical Researches》2018,39(1-2):183-203
The sediment backscatter strength measured by multibeam echosounders is a key feature for seafloor mapping either qualitative (image mosaics) or quantitative (extraction of classifying features). An important phenomenon, often underestimated, is the dependence of the backscatter level on the azimuth angle imposed by the survey line directions: strong level differences at varying azimuth can be observed in case of organized roughness of the seabed, usually caused by tide currents over sandy sediments. This paper presents a number of experimental results obtained from shallow-water cruises using a 300-kHz multibeam echosounder and specially dedicated to the study of this azimuthal effect, with a specific configuration of the survey strategy involving a systematic coverage of reference areas following “compass rose” patterns. The results show for some areas a very strong dependence of the backscatter level, up to about 10-dB differences at intermediate oblique angles, although the presence of these ripples cannot be observed directly—neither from the bathymetry data nor from the sonar image, due to the insufficient resolution capability of the sonar. An elementary modeling of backscattering from rippled interfaces explains and comforts these observations. The consequences of this backscatter dependence upon survey azimuth on the current strategies of backscatter data acquisition and exploitation are discussed. 相似文献
149.
150.
本文以灯光密度表征建设用地产出效率,采取KDE、ESDA、SDE等方法对中国县域尺度2000-2015年建设用地产出效率的总体特征、时空演变以及方向分布进行分析,研究发现:① 夜间灯光总亮度与建设用地出产出存在较强的相关关系,说明可用灯光总亮度表征建设用地产出,以灯光密度反映建设用地产出效率具有一定的科学性。② 建设用地产出效率东高西低,持续上升;增长速度西高东低,中部居中,但区域间年均增长率最大相差0.56%,整体较为均衡。③ 虽然建设用地产出效率由2000年的0.008单位灯光/km2持续上升至2015年的0.025单位灯光/km2,但其核密度曲线始终处于中低水平且右侧区间不断扩大,说明中国建设用地产出效率总体水平较低,呈现出中低水平俱乐部收敛的特征。④ 建设用地产出效率的全局 Moran's I指数都大于0,建设用地产出效率存在正向空间分布特征,且其局部空间格局变化较小,存在稳中有动,强中有弱,弱中有强的特点。⑤ 方向分布上,建设用地产出效率的方位角始终在72.420o与81.066o之间,说明东北-西南方向为建设用地产出效率的主要方向,且标准差椭圆的主轴与辅轴标准差都有所增加,说明在建设用地产出效率的主要方向与次要方向上都发生了分散现象。 相似文献