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801.
采用水提醇沉法从北芪菇中提取水溶性多糖,用Sevage法除蛋白,通过苯酚-硫酸比色法在490nm波长处测定多糖含量.在10-80μg·mL-1范围内,葡萄糖质量浓度与吸光度线性关系良好,相关系数r=0.9985,平均回收率为97.74%,相对标准偏差为2.36%(n=6),北芪菇中多糖含量为5.45%%.方法快速、简单,稳定性好,可作为北芪菇多糖的常规检测方法. 相似文献
802.
Geant4 tools were used to model the single event upset (SEU) of static random access memory cells induced by heavy ion irradiation. Simulated results obtained in two different regions of incident ion energies have been compared in order to observe the SEU occurrence by energetic ions and their effects on the radial ionization profile of deposited energy density. The disagreement of SEU cross sections of device response and radial distribution of deposited energy density have been observed in both low energy and high energy regions with equal linear energy transfer (LET) which correspond to the both sides of the Bragg peak. In the low energy region, SEUs induced by heavy ions are more dependent upon the incident ion species and radial distribution of deposited energy density, as compared with the high energy region. In addition, the velocity effect of the incident ion in silicon in the high energy region provides valuable feedback for gaining insight into the occurrence of SEU. 相似文献
803.
Bucky onions were fabricated by the DC discharge method and their behaviors and electric properties on Highly Oriented Pyrolytic Graphite (HOPG) were studied by using an atomic force microscope (AFM), a scanning tunneling microscope (STM) and a transmission electron microscope (TEM). Small-sized Bucky onions demonstrated the properties of semiconductors and as the size increased their metallicity became stronger. AFM and STM images revealed the tendency of Bucky onions to form dimers. 相似文献
805.
对目前普遍使用的期权定价二叉树模型进行了分析,利用随机误差校正方法推广出了一种新型的二叉树参数模型. 相似文献
806.
807.
Electron emission properties of single-walled carbon nanotubes (SWCNTs) assembled on a tungsten tip were investigated using field emission microscopy (FEM). The transmission electron microscopy (TEM) micrograph confirmed the existence of an SWCNT bundle on the W tip. Under appropriate experimental conditions,a series of FEM patterns with atomic resolution were obtained. These patterns arose possibly from the field emission of the open end of an individual (16,0) SWCNT protruding from the SWCNT bundle. The magnification factor and the resolution under our experimental conditions were calculated theoretically. If the value of the compression factor β was set at β= 1.76, the calculated value of the magnification factor was in agreement with the measured value. The resolving powerof FEM was determined by the resolution equation given by Gomer. The resolutionof 0.277 nm could be achieved under the typical electric field of 5.0×107 V/cm, which was close to the interatomic separation 0.246 nm between carbon atoms along the zigzag edge at the open end for the (16, 0) SWCNT. Consequently, our experimental results were further supported by our theoretical calculation. 相似文献
808.
简单介绍了国内外关于快重离子低温辐照非晶态合金引起的各向异性的塑性形变研究新进展,并对该领域今后的研究方向作了展望. Present status in study of fast heavy ion beam induced plastic deformation in amorphous alloys is briefly reviewed. Further research trend and relevant problems are also discussed. 相似文献
810.
<正> 在目前较通用的数值分析教程[1]中,对应用上较为广泛的带权的最小二乘问题进行了阐述。但是,该书没有在法方程组的系数矩阵与原问题的超定方程组的系数矩阵之间建立起明显的关系。因此,当学生第一次接触此问题时,显得有些茫然,甚至于对一个很简单的问 相似文献