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Lamyae El Gonnouni Tarek El Bardouni Mariam Zoubair Mohamed Idaomar Abderrahmane Senhoo 《原子核物理评论》2011,28(2):236-240
In this paper, we have addressed the problem of the radiation transport with the Monte Carlo N particle(MCNP) code. This is a general purpose Monte Carlo tool designed to transport neutron, photon and electron in three dimensional geometries. To examine the performance of MCNP5 code in the field of external radiotherapy, we performed the modeling of an Electron Density phantom (EDP) irradiated by photons from 60Co source. The model was used to calculate the Percent Depth Dose (PDD) at different depths in an EDP. One field size for PDD has been examined. A 60Co photons source placed at 80 cm source to surface distance (SSD). The results of calculations were compared to TPS data obtained at National Institute of Oncology of Rabat. 相似文献
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《Analytical letters》2012,45(15):2761-2762
Abstract The present note deals with the optimization of the combustion of organic materials to CO2 in Pyrex and quartz tubes. The influence of temperature and oxidant on the combustion yield was investigated. Different physical forms of CuO and a CuO/MnO2-mixture were used as oxidants. Possible isotopic effects during combustion were tested by gas isotope ratio mass spectrometry (GIRMS) of the CO2. Excellent results were obtained for combustion in Pyrex at 530 °C using CuO rods mixed with 20% MnO2 as oxidant. The stable isotope results for CO2 prepared with this method were accurate and showed a very good precision of 0.030 %. Applications for which quantitative combustion is a necessity, we suggest the use of CuO powder (< 100 μm) as oxidant and a combustion temperature of 850 °C. 相似文献
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利用动态光谱指端透射法进行了人体血液中性粒细胞百分比无创测量的研究。对21名健康志愿者进行了在体测量,选用偏最小二乘法(PLS)对获取的动态光谱数据和中性粒细胞百分比实测值进行建模分析,建立的定标集的相关系数为0.922,最大相对误差为5.85%,平均相对误差为4.13%;对定标模型的预测能力进行了验证,其中预测集的相关系数为0.912,预测集的相对误差最大为6.74%,平均相对误差为5.07。结果表明:动态光谱法可以有效地克服测量位置及人体成分等对光谱测量的影响,较准确地进行人体血液中性粒细胞百分比的测量,是一种比较好的血液成分无创测量方法,具有较高的临床应用价值。 相似文献
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Polyarylates derived from 4,4″-dihydroxy-meta-terphenyl (DHmTP) were prepared by the phase-transfer catalyzed, two-phase polycondensation with aromatic diacid chlorides. The resulting polymers were crystalline, solvent resistant, and produced brittle films. Copolymers with bisphenol-A were also synthesized using isophthaloyl diacid chloride. At low to moderate levels of DHmTP in the copolymers (25–75%), the materials had high glass transition temperatures (186–201°C), good solvent resistance, and gave tough, clear films. Terpolymers of DHmTP and BPA with 50:50 isophthaloyl and terphthaloyl diacid chloride were prepared with not much improvement over Ardel D-100®. All the DHmTP-polyarylates had good thermal stability (5% weight loss in air > 415–460°C) and had a high % char (20–48%). © 1994 John Wiley & Sons, Inc. 相似文献
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医用硬性内窥镜作为诊治医疗器械,其畸变直接影响医生对手术位置判断的准确性,因此内窥镜相对百分畸变的测量是一个亟需解决的问题。设计了一种基于图像处理的相对百分畸变检测系统,通过CCD相机采集校准靶板图像,对内窥镜视轴和目标靶板的板面进行垂直校准后,更换畸变靶板采集图像,计算机将得到的图像进行滤波、感兴趣区域提取和尺寸统计,最终获得相对百分畸变。以30°腹腔内窥镜为测量模型,实验得到设计的校准系统在待测内窥镜全视场70%位置所测量的相对百分畸变值优于未垂直校准系统2.2%。结果表明,系统的检测结果一致性较高,且准确度高于未垂直校准系统。 相似文献
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两种产地的沉香药材及水煎液中6种矿物质元素的分布特征比较 总被引:2,自引:0,他引:2
采用火焰原子吸收光谱法(FAAS)测定了两产地(海南、云南)沉香药材中的Zn、Fe、Cu、Mn、Ca和Mg6种矿物质元素的含量。根据样品中矿物质的含量计算矿物质在日服用量下的"中国营养素参考值百分比"(矿物质NRV%),然后绘制日服用量下矿物质NRV标准化分布模式图。结果表明,海南产和云南产沉香中各矿物质元素的含量及矿物质NRV标准化分布模式图都有明显差异。海南产沉香中Ca、Mg、Mn的含量分别约是云南产沉香中Ca、Mg、Mn的2倍,而云南产沉香中Fe的含量约是海南产沉香的4.6倍。海南沉香的原药和水煎液中均以Mn的NRV%最高;云南沉香原药以Fe的NRV%最高,水煎液以Mn的NRV%最高。 相似文献
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研究了微型激光扩束镜准超光滑表面的加工工艺。分析了机床速度、压力、抛光粉、工作温度、抛光模等对高质量表面的影响。选定了一系列的工艺参数,大幅度地提高了产品的合格率。 相似文献
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