排序方式: 共有23条查询结果,搜索用时 359 毫秒
1.
目的:评价磁共振胆胰管成像在肝内外胆管梗阻中的临床应用.方法:回顾分析49例磁共振水成像在胆胰管成像临床中的应用.使用GE1.5T超导型磁共振扫描仪,软件aw4.2,利用重T2使胰胆管显影并结合常规MR检查.结果:MRCP结合常规MR扫描,共49例.定位准确率100%,定性准确率91.8%.结论:MRCP结合常规MR扫描,能更好地显示腔内及腔外病变,更准确地定位、定性. 相似文献
2.
亲子旅游是国内近年来迅速升温的旅游形式,但国内对该领域的研究非常匮乏。基于"推拉"动机理论,构建"推拉阻"模型应用于亲子旅游决策研究。采用SPSS 21.0对319份有效问卷进行统计,亲子旅游决策的影响因素按照重要性依次是推力、拉力和阻力。通过因子分析得到2项推力动机("孩子主导型"和"家长主导型")、4项拉力动机("设施完善""环境优良""特色服务"和"主题鲜明")、2项阻力因子("小孩因子"和"时间与费用因子")。其中,"增加亲子感情""旅游行程安排轻松愉快"和"家长没有足够的闲暇时间"分别是最重要的推力、拉力和阻力变量。单因素方差分析显示,小孩数量与阻力的"小孩因子"呈显著正相关,小孩年龄与拉力动机的"环境优良"存在显著的正相关,家长学历对推力动机的"家长主导型"和拉力动机的"环境优良"均产生显著影响。 相似文献
3.
Spatial interaction between collapsed pipes and landslides in hilly regions with loess‐derived soils
While most studies focus on the effect of soil pipes on hillslope stability, this present study investigates the impact of landsliding on pipe development. It is hypothesized that poorly drained active and dormant landslides change the hillslope hydrology through (i) surface flow obstruction, by changing topography, as well as (ii) subsurface flow obstruction by tilting less‐permeable clay‐rich substrates. Hence, new preferential flow paths are created at reverse slopes within the landslide zone and at the boundary of the landslide, enhancing pipe formation. This study aims at a better understanding of the interaction between collapsed pipe (CP) occurrence and landslide (LS) occurrence in the Flemish Ardennes (Belgium) by comparing their respective spatial patterns. At least 24.5% of the 139 sites with CP were related to the occurrence of an observed LS. Poorly drained LS may create favourable conditions for pipe development. Outside LS, natural and anthropogenic (e.g. broken field drains, road drainage) causes may result in concentrated subsurface flow, resulting in pipe development. No evidence was found that pipe development enhanced LS, probably because the subsurface drainage discharge generated upslope of the LS is too low. Even when pipes become blocked, it is more likely that new pipes develop and new collapses occur than they trigger or reactivate LS. A conceptual model is presented summarizing all elements that influence piping erosion in the Flemish Ardennes, including the role of LS. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
4.
在传统缓冲区分析基本思想的基础上,提出基于空间对象缓冲区分析定义,区别在于邻域半径:前者为常量,后者为变量。设计实现基于空间对象缓冲区分析算法,该算法以空间对象为计算粒度,分为计算缓冲区边界点、生成缓冲区多边形、筛选缓冲区多边形内空间对象3个步骤,并从算法执行机理的角度对其做定性与定量评估。结果表明,该算法解决了传统缓冲区分析难以处理图层内以空间实体为分析粒度的问题,时间和空间复杂度亦优于传统缓冲区分析算法。 相似文献
5.
6.
利用云南省1981—2013年125站逐日逐6h地面观测的天气现象、能见度和气象要素资料,结合考虑地形高度的高分辨率气象要素场插值技术和不适航雾(能见度≤800m的大雾天气)气象要素判识模型,开展了影响云南适航条件视程障碍天气的气候特征分析。结果表明:云南最主要的视程障碍天气是雾与轻雾,影响适航条件的视程障碍天气仅为雾。不适航雾生成与相对湿度、风速以及地气温差关系密切,"高湿—弱风—稳定"的气象条件是其形成维持的关键,其量化判识特征为:相对湿度98%、风速3m/s、地气温差3℃。滇西南、滇南、滇东是云南不适航雾的多发区,尤其景东—思茅—版纳、西盟—澜沧、保山—腾冲和罗平等地区。滇中、滇西和滇东北是少发区。云南不适航雾日变化呈现早晨和深夜多,午间和傍晚少的特征;季节变化具有夏秋季多于冬春季的特点。与台站观测相比,高分辨率资料客观判识的不适航雾空间分布与地形有合理的对应关系,能够合理地反映地形复杂地区的空间分布特征。未来技术发展可利用卫星反演资料与台站资料同化订正获取高分辨率气象要素资料,利用深度学习等建立不适航雾的判识模型。 相似文献
7.
目的:探讨MSCT多平面及曲面重组技术在机械性肠梗阻诊断中价值。方法:36例经手术、结肠镜病理证实或临床明确诊断的肠梗阻患者,行腹部MSCT平扫,扫描后进行回顾性0.6mm到1.0mm薄层重建,图像后处理技术包括MPR、CPR、MIP等,观察扩张积气的肠管、移行区和肠系膜,从而判断梗阻部位、梗阻原因及肠管血运状况。结果:粘连性肠梗阻21例,肠道肿瘤7例,炎症性肠梗阻5例,胆石性肠梗阻1例,肠扭转1例,腹外疝1例。正确诊断率为92.00%(32/36)。结论:横断位图像基础上增加MPR、CPR等MSCT图像重组技术,在明确肠梗阻病因、部位及性质等方面有重要临床价值,可以作为肠梗阻诊断的首选检查方法。 相似文献
8.
9.
10.
The topography, occurrence mechanism and lithology are the important factors of landslide movement. The lithology, seismic intensity, geological structure and topography in the travel path of 215 incomplete obstruction landslides with volumes more than 104m3 induced by Wenchuan earthquake were studied. Based on the classification of the factors established, we studied the factors influencing the movement distance of incomplete obstruction landslides. The following results are drawn. In the influence factors of topography in the travel path, the distance is largest in the straight valley topography, followed by the concave, ladder, turning valley, slope toe-type and slope-type landslides, in turn. The topography not only has remarkable influence on the distance of large-scale landslides, but also on the medium and small-scale landslides as well, which is the most important factor influencing the distance. The formation mechanism controlled by lithology, seismic intensity and geological structure has little influence on the mobility of medium-and small-scale landslides. For the large-scale landslides with volume more than 106m3, the distance of landslide with medium hard rock is larger than landslides with hard and soft rock. In the seismic intensity Ⅸ to Ⅺ areas, the landslide distance decreases with intensity increasing, contrary to the distribution of landslide-point density and landslide-area density. The geological structure has influence on the slide aspect of landslides and occurrence mechanism, but the influence is not remarkable to the landslide movement distance. 相似文献