目的分层分析是将数据按照某个(些)需要控制的变量进行分层,然后再估计暴露与结局之间关联强度的一种资料分析方法,是肿瘤流行病学研究中最常用的控制混杂的方法之一。本研究旨在应用R软件的epiR软件包实现肿瘤流行病学资料的分层分析,...目的分层分析是将数据按照某个(些)需要控制的变量进行分层,然后再估计暴露与结局之间关联强度的一种资料分析方法,是肿瘤流行病学研究中最常用的控制混杂的方法之一。本研究旨在应用R软件的epiR软件包实现肿瘤流行病学资料的分层分析,为识别和控制混杂因素提供新的统计学工具。方法结合2009年的一项关于乳腺癌的病例对照研究数据,以体质指数(body mass index,BMI)为分层变量,分析血清中抵抗素含量和乳腺癌发病的关系,计算采用epiR软件包实现。结果未经BMI调整时,血清中抵抗素含量与乳腺癌发生的关联强度ORc=3.431(95%CI:1.590~7.406),P=0.001;经BMI分层调整后,血清中抵抗素含量与乳腺癌发生的关联强度ORmh=3.809(95%CI:1.703~8.518),P=0.001。结论调整BMI混杂因素的影响之后,血清中抵抗素含量与乳腺癌发生的关联性依然存在,表明血清中抵抗素含量可能是乳腺癌的危险因素之一。epiR软件包程序书写简单,结果输出丰富,能方便地完成分层分析,可以为肿瘤流行病学研究人员开展分层分析提供参考。展开更多
Nd1-xSrxMnO3 （x ： 0.3, 0.5） ceramics containing a secondary phase are synthesized by high-energy ball milling and post heat-treatment method. The 4-wire and 2-wire measuring modes are used to investigate the transp...Nd1-xSrxMnO3 （x ： 0.3, 0.5） ceramics containing a secondary phase are synthesized by high-energy ball milling and post heat-treatment method. The 4-wire and 2-wire measuring modes are used to investigate the transport character of the grain/phase boundary （inner interface） and electrode-bulk interface （outer interface）, respectively, and the results indicate that there is a similar nonlinear I-V behaviour for both of the inner and outer interfaces, however, the electric pulse induced resistance change （EPIR） effect can only be observed at the outer interface.展开更多
The electric-pulse-induced resistive switching effect is studied for Tio.s5Cro.15Ox （TCO） films grown on Ir-Si substrates by pulsed laser deposition. Such a TCO device exhibits bipolar switching behaviour with an el...The electric-pulse-induced resistive switching effect is studied for Tio.s5Cro.15Ox （TCO） films grown on Ir-Si substrates by pulsed laser deposition. Such a TCO device exhibits bipolar switching behaviour with an electric-pulse- induced resistance ratio as large as about 1000% and threshold voltages smaller than 2 V. The resistive switching characteristics may be understood by resistance changes of a Schottky junction composed of a metal and an n-type semiconductor, and its nonvolatility is attributed to the movement of oxygen vacancies near the interface.展开更多
We report that fully transparent resistive random access memory （TRRAM） devices based on ITO/TiO2/ITO sandwich structure, which are prepared by the method of RF magnetron sputtering, exhibit excellent switching stab...We report that fully transparent resistive random access memory （TRRAM） devices based on ITO/TiO2/ITO sandwich structure, which are prepared by the method of RF magnetron sputtering, exhibit excellent switching stability. In the visible region （400 800 nm in wavelength） the TRRAM device has a transmittance of more than 80%. The fabricated TRRAM device shows a bipolar resistance switching behaviour at low voltage, while the retention test and rewrite cycles of more than 300,000 indicate the enhancement of switching capability. The mechanism of resistance switching is further explained by the forming and rupture processes of the filament in the TiO2 layer with the help of more oxygen vacancies which are provided by the transparent ITO electrodes.展开更多
文摘以Na2S溶液为沉积液,在一定的温度、pH值、电压和时间下,采用电化学沉积的方法,在铜衬底上生长出一层质地均匀的蓝色Cu2S薄膜.通过XRD及SEM对样品的化学成分及表面与截面形貌进行表征,对Ag/Cu2S/Cu/Ag结构进行直流I-V及电脉冲诱导电阻转变(EPIR)效应测试.结果表明Ag/Cu2S/Cu/Ag结构的Ag/Cu2S结点处存在明显的EPIR效应,而且相对于单个Ag/Cu2S结点而言,Ag/Cu2S双结点具有更大的结点电阻且EPIR效应更明显.另外,Ag/Cu2S/Cu/Ag结构的EPIR效应还与测量的脉冲参数和测量温度有关.对于本样品而言,最佳测量温度为室温,脉冲宽度t0为0.000 1 s.
文摘目的分层分析是将数据按照某个(些)需要控制的变量进行分层,然后再估计暴露与结局之间关联强度的一种资料分析方法,是肿瘤流行病学研究中最常用的控制混杂的方法之一。本研究旨在应用R软件的epiR软件包实现肿瘤流行病学资料的分层分析,为识别和控制混杂因素提供新的统计学工具。方法结合2009年的一项关于乳腺癌的病例对照研究数据,以体质指数(body mass index,BMI)为分层变量,分析血清中抵抗素含量和乳腺癌发病的关系,计算采用epiR软件包实现。结果未经BMI调整时,血清中抵抗素含量与乳腺癌发生的关联强度ORc=3.431(95%CI:1.590~7.406),P=0.001;经BMI分层调整后,血清中抵抗素含量与乳腺癌发生的关联强度ORmh=3.809(95%CI:1.703~8.518),P=0.001。结论调整BMI混杂因素的影响之后,血清中抵抗素含量与乳腺癌发生的关联性依然存在,表明血清中抵抗素含量可能是乳腺癌的危险因素之一。epiR软件包程序书写简单,结果输出丰富,能方便地完成分层分析,可以为肿瘤流行病学研究人员开展分层分析提供参考。
基金the Project of Hubei Polytechnic University (No.12xjz01R)The Natural Science Foundation of Hubei Province(No.2012FFB01001)the Program of Ministry of Education of China(for New Century Excellent Talents in University, No.NCET-08-0674)for their financial supports
文摘Nd1-xSrxMnO3 （x ： 0.3, 0.5） ceramics containing a secondary phase are synthesized by high-energy ball milling and post heat-treatment method. The 4-wire and 2-wire measuring modes are used to investigate the transport character of the grain/phase boundary （inner interface） and electrode-bulk interface （outer interface）, respectively, and the results indicate that there is a similar nonlinear I-V behaviour for both of the inner and outer interfaces, however, the electric pulse induced resistance change （EPIR） effect can only be observed at the outer interface.
基金Project supported by NASA,the State of Texas through the Center for Advanced Materials,Sharp Laboratories of America,Semiconductor Research Corporation,the R.A.Welch Foundation (Grant No.#E-632)the National Natural Science Foundation of China (Grant No.11074109)+2 种基金the Natural Science Foundation of Jiangsu Province of China (Grant No.SBK200920627)the National Basic Research Program of China (Grant No.2010CB923404)the National "Climbing" Program of China (Grant No.91021003)
文摘The electric-pulse-induced resistive switching effect is studied for Tio.s5Cro.15Ox （TCO） films grown on Ir-Si substrates by pulsed laser deposition. Such a TCO device exhibits bipolar switching behaviour with an electric-pulse- induced resistance ratio as large as about 1000% and threshold voltages smaller than 2 V. The resistive switching characteristics may be understood by resistance changes of a Schottky junction composed of a metal and an n-type semiconductor, and its nonvolatility is attributed to the movement of oxygen vacancies near the interface.
基金Project supported by the National Basic Research Program of China (Grant No. 2007CB925002)the National High Technology Research and Development Program of China (Grant No. 2008AA031401)and Chinese Academy of Sciences
文摘We report that fully transparent resistive random access memory （TRRAM） devices based on ITO/TiO2/ITO sandwich structure, which are prepared by the method of RF magnetron sputtering, exhibit excellent switching stability. In the visible region （400 800 nm in wavelength） the TRRAM device has a transmittance of more than 80%. The fabricated TRRAM device shows a bipolar resistance switching behaviour at low voltage, while the retention test and rewrite cycles of more than 300,000 indicate the enhancement of switching capability. The mechanism of resistance switching is further explained by the forming and rupture processes of the filament in the TiO2 layer with the help of more oxygen vacancies which are provided by the transparent ITO electrodes.
