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主成分抽取数量确定方法的改进 被引量:1
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作者 尹波 刘明理 鲁若愚 《统计与决策》 CSSCI 北大核心 2010年第16期4-6,共3页
主成分抽取数量的确定是主成分分析中的关键问题。文章提出一种新的确定方法,首先采用加速系数和最优协调两个数量指标来确定主成分抽取的数量;然后基于Bootstrap再抽样数据采用Horn平行检验来验证主成分数量模型的稳定性。实例研究表明... 主成分抽取数量的确定是主成分分析中的关键问题。文章提出一种新的确定方法,首先采用加速系数和最优协调两个数量指标来确定主成分抽取的数量;然后基于Bootstrap再抽样数据采用Horn平行检验来验证主成分数量模型的稳定性。实例研究表明,本文提出的方法,相比特征值大于1、解释的总方差比例和Scree图形等方法,结果更客观、准确和稳定,可广泛应用于主成分分析等相关研究中。 展开更多
关键词 Cattell Scree方法 加速系数 最优协调 平行检验
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Screening for hepatocellular carcinoma by Egyptian physicians
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作者 Sahar M Hassany Ehab F Abdou Moustafa +2 位作者 Mohamed El Taher Afaf Adel Abdeltwab Hubert E Blum 《World Journal of Gastrointestinal Oncology》 SCIE CAS 2015年第9期161-171,共11页
AIM: To assess the practice of Egyptian physicians in screening patients for hepatocellular carcinoma(HCC). METHODS: The study included 154 physicians from all over Egypt caring for patients at risk for HCC. The study... AIM: To assess the practice of Egyptian physicians in screening patients for hepatocellular carcinoma(HCC). METHODS: The study included 154 physicians from all over Egypt caring for patients at risk for HCC. The study was based on a questionnaire with 20 items. Each questionnaire consisted of two parts:(1) personal information regarding the physician(name, age, specialty and type of health care setting); and(2) professional experience in the care of patients at risk for HCC development(screening, knowledge about the cause and natural course of liver diseases and HCC risk). RESULTS: Sixty-eight percent of doctors with an MD degree, 48% of doctors with a master degree or a diploma and 40% of doctors with a Bachelor of Medicine, Bachelor of Surgery certificate considered the hepatitis C virus(HCV) genotype as risk factor for HCC development(P < 0.05). Ninety percent of physicians specialized in tropical medicine, internal medicine or gastroenterology and 67% of physicians in other specialties advise patients to undergo screening for HCV and hepatitis B virus infection as well as liver cirrhosis(P < 0.05). Eighty-six percent of doctors in University Hospitals and 69% of Ministry of Health(MOH) doctors consider HCV infection as the leading cause of HCC in Egypt(P < 0.05). Seventy-two percent of doctors with an MD degree, 55% of doctors with a master degree or a diploma, 56% of doctors with an MBBCH certificate, 74% of doctors in University Hospitals and 46% of MOH hospital doctors consider abdominal ultrasonography as the most important investigation in HCC screening(P < 0.05). Sixty-five percent of physicians in tropical medicine, internal medicine or gastroenterology and 37% of physicians in other specialties recommend as HCC screening interval of 3 mo(P < 0.05). Seventy-one percent of doctors with an MD degree, 50% of doctors with a master degree or diploma and 60% of doctors with an MBBCH certificate follow the same recommendation.CONCLUSION: In Egypt, physicians specialized in tropical medicine, internal medicine or gastroenterology with an MD degree and working in a University Hospital are best informed about HCC. 展开更多
关键词 HEPATOCELLULAR CARCINOMA EGYPTIAN PHYSICIANS Scree
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快速截图,心随我动
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作者 刀鱼工作室 《网友世界》 2005年第2期17-18,共2页
首先下载并安装TNT scree Capture(一下简称TNT)由于安装过程十分简单只要一路单击“下一步”按钮即可完成安装。安装完成之后双击桌面上的快捷图标即可进入到TNT的主界面。
关键词 下载软件 TNT scree CAPTURE 网络聊天软件 计算机网络
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Scree conglomerate and its derivatives in the Upper Cretaceous Kallankurichchi Limestone,Ariyalur Group,Cauvery Basin,South India
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作者 Shilpa Srimani 《Journal of Palaeogeography》 SCIE CSCD 2024年第3期495-508,共14页
The repetitive influx of coarse clastics of mixed composition,siliciclastics and carbonates,locally common in the lower part of the Upper Cretaceous marine Kallankurichchi Limestone specifies a resurgence of tectonic ... The repetitive influx of coarse clastics of mixed composition,siliciclastics and carbonates,locally common in the lower part of the Upper Cretaceous marine Kallankurichchi Limestone specifies a resurgence of tectonic unrest in the Cauvery rift basin,India.The basin-margin scree and its derivatives elicit diverse modes of emplacement and differ in many ways from denoting it only as basal conglomerate.The study meticulously reveals the depositional history of these basin-margin coarse clastics.The scree conglomerate bodies are wedge-shaped in appearance and often have flat,eroded tops.At places,their surfaces,tops and flanks,are encrusted with Inoceramus although internally,they are mostly unfossiliferous.They are clast-supported and extremely poorly sorted,having interstitial spaces filled by sand-sized grains at the basal part.The clasts can be traced into the underlying Sillakuddi Sandstone and the granitic basement.The clasts derived from the sandstone are angular and measure up to 60 cm in length,while the basement-derived clasts dominate the smaller(maximum diameter measured 5 cm)and more rounded population.The elongated clasts are chaotically arranged,even oriented sub-vertically,reclining on other clasts.The lowermost scree conglomerate has a sharp base,and the pebbles sunk into the underlying sandstone,although no discernible impact laminae wrapping their bottom were ever observed.Evidently,the scree fans were initiated under the sea,which permitted the slow sinking of assorted rock fragments dropped from above.The sporadic occurrence of marine fossils further corroborates this contention.The scree conglomerates at different stratigraphic levels transitioned laterally into conglomerates of mass flow origin and then to massive calcarenite,together forming wedge-shaped bodies.The initial alignment of clasts parallel to bedding transforms to a chaotic alignment representing the transition from internally sheared flow to debris flow and associated shapes.Matrixsupported fabric grades into massive calcarenite,suggesting gravity-driven transformation.Further down the wedge,the massive calcarenite turns into cross-stratified facies,making it evident that laminar flow turned turbulent in the course of body transformation of the sediment-driving flows.It can be presumed that these flows were triggered by subsidence,which resulted from renewed gaps in formation and led to the collapse of scree cones.Facies variability suggests scree deposits giving way downslope to debris flow and related deposits.Eventually,all the scree products pass laterally into the carbonate formation basinwards. 展开更多
关键词 Scree conglomerate Kallankurichchi Limestone Tectonic subsidence Flow transformation Cauvery Basin
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