排序方式: 共有17条查询结果,搜索用时 15 毫秒
1.
Nick Kontogeorgopoulos 《GeoJournal》2005,61(1):1-11
The desire to spend leisure time in natural settings represents a key factor behind the recent and rapid growth of ecotourism. A search by ecotourists for remote landscapes and locations has shaped the way in which geographers have defined ecotourism, but few scholars have explored, in detail, the mechanics of the spatial relationship between ecotourism and mass tourism, two forms of travel usually considered mutually exclusive in spatial terms. Using the island of Phuket — southern Thailands premier resort destination — as a case study, this paper investigates the spatial overlaps and connections between ecotourism and mass tourism and tests the assumption that ecotourism and mass tourism must exist spatially apart in order for the former to succeed. Despite Phukets association with mass tourism, and the small physical distances between built-up mass tourist areas and natural ecotourism settings, the communicative staging of natural authenticity allows ecotourism companies to convey geographical remoteness to tourists. Although ecotourism in Phuket must struggle constantly to overcome the perceptual impact of spatial proximity to resort locations, the tourist markets and business networks of the existing mass tourism industry remain crucial to the survival of ecotourism in this region. Thus, contrary to conventional notions that ecotourism and mass tourism must exist as separate entities, this paper argues that an interconnected, symbiotic, and spatially-contiguous relationship between the two is necessary in the case of Phuket. 相似文献
2.
3.
目的:采用高分辨率小FOV双重造影结合DWI扫描技术,探讨磁共振成像(MRI)对直肠癌术前分期的意义。方法:收集2013年1月至2016年1月直肠癌的病例250例,综合所有序列对直肠癌病灶进行术前MRI-TN分期,评估直肠系膜筋膜和环周切缘是否累及,并与手术病理结果进行对照分析。结果:MRI T分期准确率为88.8%(222/250),MRI诊断直肠癌各T分期的准确率、敏感性、特异性、阳性预测值及阴性预测值与术后病理T分期的一致性较好,Kappa值=0.712,P=0.000。N分期准确率为75.6%(189/250),MRI诊断各N分期的准确率、敏感性、特异性、阳性预测值及阴性预测值,与术后病理的一致性为中度一致,Kappa值=0.623,P=0.000。环周切缘准确率为97.6%(58/52)。敏感性100%、特异性97.0%、阳性预测值及阴性预测值分别为89.7%、100%。结论:1薄层、小FOV高分辨率MRI双重造影结合DWI可以多参数、多角度对直肠癌术前T分期做出准确的分期,对N分期做出较准确分期。2 MRI可以对环周切缘有无累及进行准确的预测。3矢状位能准确测量肿瘤下缘距肛缘的距离,为术前评估是否保肛提供直观信息。 相似文献
4.
目的:评估磁共振二维T2加权自旋回波成像序列(2D-T2WI TSE)与三维T2加权自旋回波成像序列(3D-T2WI TSE,VISTA)两种成像方法在直肠癌术前分期的准确性。方法:采用飞利浦3.0T MR机扫描,由两位放射科医师独立评估,回顾性分析从2016年1月至2016年4月间经病理确诊的33例直肠癌患者的2D-MRI序列及3D VISTA扫描序列图像。运用SPSS统计软件分别分析2D序列及3D VISTA序列对直肠癌术前T、N分期的准确性,并检验诊断结果的一致性。结果:33例病例,医师1与医师2其常规2D和3D VISTA检查序列T分期的准确性分别为70%和85%(P=0.274)及73%和82%(P=0.454),Kappa分别为0.576和0.790及0.618和0.746,3D VISTA序列评估T分期与病理结果的一致性优于2D序列;其N分期的准确性分别为58%和70%(P=0.182)及58%和67%(P=0.218),Kappa分别为0.252和0.407及0.267和0.376,N分期2D及3D VISTA分期与病理结果的一致性较差。结论:2D与3D VISTA序列对直肠癌TN分期的准确性无统计学差异,但是3D VISTA较2D序列在鉴别T2与早期T3及N分期方面有一定潜在优势。 相似文献
5.
目的:探讨多层螺旋CT对尘肺患者不同分期中主肺动脉血流动力学变化的评估价值。方法:选取我院收治的100例尘肺患者作为研究组,同时选取30例健康人群作为对照组。对所有人员进行X线胸片及多层螺旋CT检测,对比分析不同分期尘肺患者及健康人群的主肺动脉直径、平均流速、血流峰值和单位时间内流量等参数。结果:健康人群的肺动脉平均流速、血流峰值及单位时间内流量明显高于尘肺患者,且尘肺患者的肺动脉平均流速、血流峰值及单位时间内流量与尘肺分期成反比,差异具有统计学意义(P<0.05),健康人群的主动脉直径明显低于尘肺患者,且尘肺患者动脉直径尘肺分期成正比,差异具有统计学意义(P<0.05);多层螺旋CT的阳性检出率明显高于X线胸片,差异具有统计学意义。结论:多层螺旋CT扫描可有效检测不同分期尘肺患者主肺动脉血流动力学变化情况,可为尘肺分期提供有效参考资料。 相似文献
6.
目的:分析和研究MRI减影技术结合DWI在直肠癌术前TN分期的临床应用价值。方法:收集2010年8月~2013年12月期间经我院外科手术及病理证实的原发直肠癌患者53例。MRI序列包括常规TSE-T1WI、-T2WI、弥散成像(DWI)及反转恢复频率饱和成像(SPIR)序列。全部患者均行多方位增强扫描,而且保证有一个方位必须垂直肿块所在平面的肠管长轴,将增强扫描前后同方位图像进行减影处理,由两名高年资专家读片,并作术前TN分期。病理参考标准以Dukes分期为标准,并用Kappa方法检验MRI减影技术在直肠癌术前分期与病理结果一致性差异,统计学处理采用SPASS 19.0。结果:53例直肠癌患者中,MRI减影技术结合DWI对直肠癌检出率为100%,正确T分期49例,过低分期1例,过高分期3例,准确率为92.5%(49/53),与病理结果一致性较好。按照MRI术前提示,手术切除淋巴结283枚,53例患者术后病检伴有淋巴结转移者36例,转移性淋巴结184枚,DWI结合常规序列术前评价淋巴结转移可靠性大。结论:MRI减影技术结合DWI方便、快捷,对直肠癌的诊断及术前TN分期准确性高,值得推广应用。 相似文献
7.
8.
This paper presents a spatial decision support system for network design problems in which different kinds of projects can
be built in stages over time. It was developed by the World Bank and China's Ministry of Railways to plan investment strategies
for China's overburdened railway system. We first present a mixed-integer program for the single-period network design problem
with project choices such as single or multiple tracks and/or electrification with economies of scale. Then, because such
projects can be built all at once or in stages, we developed a heuristic backwards time sequencing procedure with a cost adjustment
factor to solve the “project staging” problem. Other innovations include a preloading routine; coordinated modeling of arcs,
paths, and corridors; and a custom-built GIS.
Received: 5 May 2000/Accepted: 11 August 2000 相似文献
9.
10.
16层螺旋CT与钡灌肠在结直肠癌诊断的对比研究 总被引:1,自引:0,他引:1
目的:探讨16层螺旋CT在中晚期结直肠癌诊断中的应用价值.材料与方法:对35例经病理证实的结直肠癌病人进行回顾性分析.通过MS-CTC检查进行术前Duke's分期,并与手术病理分期对照分析.结果:BE检查32例,BE对结直肠病变的敏感度为97.5%,准确度为84.4%;MS-CTC检查35例,MS-CTC对结直肠病变的敏感度为100%,准确度为91.4%.MS-CTC对Duke's分期诊断准确度率为85.7%.结论:BE是结直肠癌的常规影像学检查方法,MS-CTC检查能够提供多方面的诊断信息,对结直肠癌的诊断及术前分期都有重要价值. 相似文献