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111.
112.
《Computational statistics & data analysis》2008,52(12):6027-6043
Spatial cluster modelling of small area disease incidence and mortality has previously focused on clusters where excess risk is distributed around fixed points, and the aim is the reconstruction of these points (cluster centers). Often there is a need to assess clusters of a different form, such as around roads or river systems. These clusters are often linear or can be approximated by combinations of several linear segments. In this paper the recovery of point and line clusters is considered jointly. An example application is given where both linear or point clustering could be present. 相似文献
113.
《Expert systems with applications》2008,34(4):1054-1062
This paper intends to an integrated view of implementing automated diagnostic systems for breast cancer detection. The major objective of the paper is to be a guide for the readers, who want to develop an automated decision support system for detection of breast cancer. Because of the importance of making the right decision, better classification procedures for breast cancer have been searched. The classification accuracies of different classifiers, namely multilayer perceptron neural network (MLPNN), combined neural network (CNN), probabilistic neural network (PNN), recurrent neural network (RNN) and support vector machine (SVM), which were trained on the attributes of each record in the Wisconsin breast cancer database, were compared. The purpose was to determine an optimum classification scheme with high diagnostic accuracy for this problem. This research demonstrated that the SVM achieved diagnostic accuracies which were higher than that of the other automated diagnostic systems. 相似文献
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115.
Jiamei Hu Xin Jia Cuihua Li Zhiyuan Ma Guoxiang Zhang Wenbo Sheng Xiulan Zhang Zhong Wei 《Journal of Materials Science》2014,49(7):2943-2951
In this work, graphene oxide (GO) and poly(methyl methacrylate) (PMMA) grafted GO reduced by dopamine (rGO@PDA-g-PMMA) were employed to determine the key factor responsible for the improved mechanical properties of poly(vinyl chloride) (PVC). Dopamine was utilized to reduce GO and simultaneous coating of polydopamine (PDA) on the GO surface. rGO@PDA-g-PMMA was prepared by a combination of mussel-inspired chemistry and surface-initiated atom transfer radical polymerization techniques. The resulting derivatives were characterized by thermogravimetric analysis, Fourier transforms infrared spectroscopy, X-ray diffraction, and Raman spectroscopy. PVC nanocomposites containing GO derivatives were prepared by solution blend and the nanocomposite films were obtained using a casting method. The mechanical properties of the nanocomposites were studied using both dynamic mechanical thermal analysis and tensile testing. The results revealed that the vital components responsible for the improved mechanical properties and thermal stability of rGO@PDA-g-PMMA/PVC nanocomposites compared to pure PVC are the interfacial interactions between the GO derivatives and the PVC matrix. 相似文献
116.
The structural and electronic properties of the recently synthesized superhard BC5 are studied by using density functional theory within the generalized gradient approximation (GGA). P3m1-II structure is confirmed as the most stable state of BC5 by comparing three potential structures. The high-pressure effect on superhard BC5 is also successfully calculated. The obtained pressure dependence of structural property shows that the compressibility along three cell vectors is very close to each other. Based on the density of states (DOS), we find high pressure hardly change the DOS at Fermi level (EF) which is related closely to the transition temperature Tc. The result is useful to further study the superconductivity of BC5. 相似文献
117.
《Journal of power sources》2006,156(2):224-231
One way to alleviate the emission of air pollutants and CO2 due to burning fossil fuels is the use of fuel cells. Sputter deposition techniques are good candidates for the fabrication of electrodes used for proton exchange membrane fuel cells (PEMFCs). Input power and sputtering-gas pressure are two important parameters in a sputtering process. However, little is known about the effects of these sputtering parameters on the performance of PEMFC electrodes. Therefore, this study applied a radio frequency (RF) magnetron sputter deposition process to prepare PEMFC electrodes and investigated the effects of RF power and sputtering-gas pressure in electrode fabrication on electrode/cell performance. At a Pt loading of 0.1 mg cm−2, the electrode fabricated at 100 W, 10−3 Torr was found to exhibit the best performance mainly due to its lowest kinetic (activation) resistance (dominating the cell performance) in comparison to those fabricated by 50 and 150 W at 10−3 Torr, as well as by 10−4 and 10−2 Torr at 100 W. In the tested ranges, the control of sputtering-gas pressure seems to be more critical than that of RF power for the activation loss. In addition to electrochemically active surface area, electrode microstructure should also be responsible for electrode/cell polarization, particularly the activation polarization. 相似文献
118.
《International Journal of Hydrogen Energy》2022,47(90):38229-38241
Selective hydrogenation of α, β-unsaturated aldehydes has always been a hot research topic owing to favorable thermodynamics in CC hydrogenation. In this work, a series of Pd/SnO2 nanocatalysts were facilely synthesized under mild conditions, via the reduction of Na2PdCl4 by dimethylaminoborane. Under galvanostatic electrolysis at 3.33 mA cm?2 for 8 h, the selective conversion of cinnamaldehyde (CAL) was achieved over Pd/SnO2-coated carbon fiber in neutral phosphate buffer, giving the cinnamyl alcohol (COL) selectivity of 78.85% at the conversion of 84.88%. The Pd/SnO2 nanocatalysts outperform commercial Pd/C catalysts, showing high COL selectivity and faradaic efficiency. The cathodic reduction potential of CAL over Pd4·3/SnO2 occurs at ?0.92 V. The SnO2 support is beneficial to promote the CO adsorption of CAL and lower the HER activity of Pd nanocatalysts, thereby contributing to superior activity of Pd4·3/SnO2 for selective hydrogenation of CAL. 相似文献
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120.
目的探讨多层螺旋CT(MSCT)血管成像技术(MSCT angiography,MSCTA)在门静脉高压症(portal hy-pertension,PHT)诊断及临床治疗中的价值。方法对50例PHT患者者行MSCTA,观察患者门静脉系统的解剖学类型、门静脉主干及其分支侧支循环显示情况;观察食管胃底静脉曲张的形态、位置及血供类型。结果 50例门静脉高压症患者门静脉及侧支循环显影包括:食管下段静脉曲张94.0%,胃底静脉曲张90.0%,胃左静脉曲张90.0%,食管旁静脉曲张72.0%,胃短、胃后静脉曲张32.0%,脾/胃-肾静脉分流28.0%,副脐静脉、腹壁静脉曲张26.0%,腹膜后-椎旁静脉曲张22.0%。对21例患者施行手术,手术与影像学诊断完全符合。MSCTA检出胃静脉曲张(gastric varices,GV)阳性49例所见的病状与胃镜下所见病状对比一致性较好。结论 MSCTA能为PHT患者判断病变程度、预测其并发症及选择治疗方案提供可靠的依据。 相似文献