排序方式: 共有118条查询结果,搜索用时 31 毫秒
91.
采用美国军用标准MIL-PRF-13830B(简称美标)对光学元件表面疵病进行数字化评价,其难点主要在于美标中表面疵病密集度的判定。针对该难点,提出了一种表面疵病密集度判定算法。该算法采用权重域叠加的方法,通过为表面疵病赋予相应的权重域来确定疵病密集圆域,并将权重域间的叠加转换成了矩阵间位置关系的判断和计算,有效的利用了矩阵运算的便利性。实验中通过对已知表面疵病信息的石英标准板进行判定,其得到的圆域即为疪病密集圆域,与预期结果一致,验证了该算法的正确性。目前该算法已经运用于光学车间精密光学元件表面疵病的美标数字化评价。 相似文献
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Single crystalline boron nanocones are prepared by using a simple spin spread method in which Fe 3 O 4 nanoparticles are pre-manipulated on Si(111) to form catalyst patterns of different densities.The density of boron nanocones can be tuned by changing the concentration of catalyst nanoparticles.High-resolution transmission electron microscopy analysis shows that the boron nanocone has a β-tetragonal structure with good crystallization.The field emission behaviour is optimal when the spacing distance is close to the nanocone length,which indicates that this simple spin spread method has great potential applications in electron emission nanodevices. 相似文献
93.
Surface-enhanced Raman scattering properties of highly ordered self-assemblies of gold nanorods with different aspect ratios 下载免费PDF全文
Gold nanorods with aspect ratios of from 1 (particles) to 31.6 were synthesized by the seed-mediated method and packed in a highly ordered structure on a large scale on silicon substrates through capillary force induced self-assembly behaviour during solvent evaporation.The gold nanorod surface exhibits a strong enhancing effect on Raman scattering spectroscopy.The enhancement of Raman scattering for two model molecules (2-naphthalenethiol and rhodamine 6G) is about 5-6 orders of magnitude.By changing the aspect ratio of the Au nanorods,we found that the enhancement factors decreased with the increase of aspect ratios.The observed Raman scattering enhancement is strong and should be ascribed to the surface plasmon coupling between closely packed nanorods,which may result in huge local electromagnetic field enhancements in those confined junctions. 相似文献
94.
设计制备了以泊洛沙姆407/188为主要基质,卡波姆、氯化钠为添加剂,月桂酸二乙醇酰胺为增溶剂的双氯芬酸钠缓释液体栓,以凝胶温度、凝胶强度、生物黏附力和体外释放度为考察指标进行体外评价;测定双氯芬酸钠缓释液体栓在犬体内的血药浓度,进行体内筛选.采用3p97软件计算液体栓相关药动学参数,进行体内释药特性研究.加入0.9%月桂酸二乙醇酰胺使双氯芬酸钠增溶2.3倍.缓释液体栓体外释放符合零级模式,R20.9,释药时限大于6h;体内药物释放出现血药平台,具有良好的体内外相关性;体内过程为一室模型,t1/2(Ke)=5.553 3h,t1/2(Ka)=0.357 4h,cmax=7 712ng.mL-1,AUC0→∞=72 029ng.h.mL-1,MRT=7.61h.所制备的双氯芬酸钠缓释液体栓具有稳定的缓控释特性. 相似文献
95.
Influence of tube voltage and current on in-line phase contrast imaging using a microfocus x-ray source 下载免费PDF全文
In-line x-ray phase contrast imaging has attracted much attention due
to two major advantages: its effectiveness in imaging weakly
absorbing materials, and the simplicity of its facilities. In this
paper a comprehensive theory based on Wigner distribution developed
by Wu and Liu [Med. Phys. 31 2378-2384 (2004)] is reviewed. The
influence of x-ray source and detector on the image is discussed.
Experiments using a microfocus x-ray source and a CCD detector are
conducted, which show the role of two key factors on imaging: the
tube voltage and tube current. High tube current and moderate tube
voltage are suggested for imaging. 相似文献
96.
钙钛矿前驱体(PbI2和CH3NH3I)分散体系,作为一种新型染料敏化太阳能电池(Dye-sensitized Solar Cells,DSSCs)电解质,光电流和光电压的继续提升是其发展过程中亟待解决的问题.在本工作中,研究发现,通过引入二甲基碘化铵(DMAI)作为钙钛矿前驱体电解质的高效添加剂,可将光电流密度从12.85 mA·cm-2急剧提升至19.19 mA· cm-2.借助阻抗和塔菲尔曲线分析,发现其光电流的增加与TiO2半导体导带的向上移动对不平衡载流子复合的抑制作用具有一定的相关性.进一步通过叔丁基吡啶的调节作用,可将光电转换效率提高到8.46%,超过了传统的碘电解质.也为染料敏化太阳能电池的研究开辟了新的途径. 相似文献
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建立丹磺酰氯柱前衍生-超高效液相色谱-串联质谱法测定人体尿样中环己胺的方法。冷冻样品经解冻、离心后,用丹磺酰氯衍生,固相萃取小柱净化。目标化合物采用 Waters ACQUITY CSHTM C18色谱柱(50 mm×2.1 mm,1.7μm)分离,以甲醇和0.002 mol/L乙酸铵溶液为流动相梯度洗脱,采用电喷雾离子源电离、正离子多反应监测模式质谱检测。环己胺在2.5~200μg/L浓度范围内有较好的线性关系,相关系数大于0.999,回收率为98.7%~102.3%,精密度为3.1%~5.2%,检出限和定量限分别为1.0和3.0μg/L。结果表明,本方法操作简单、准确可靠,可适用于人体尿液中环己胺的定量分析。应用本方法测定200份学生尿液样品,环己胺检出率为34.5%。 相似文献
100.
以浮动催化热分解法制备碳纳米管(CNTs), 采用氧化-还原-硫化的方法制备了CNTs/FeS催化剂, 采用X射线衍射(XRD)、 透射电子显微镜(TEM)和热重(TG)分析等技术对催化剂进行了结构表征. 将CNTs/FeS作为类Fenton催化剂用于水中环丙沙星的去除, 研究了降解过程中H2O2浓度、 CNTs/FeS催化剂的投加量、 环丙沙星浓度及pH等因素对催化降解性能的影响. 结果表明, CNTs/FeS类Fenton催化反应在H2O2浓度为20 mmol/L和CNTs/FeS催化剂的投加量为10 mg的条件下具有最优的降解效果, 其催化反应过程符合一级动力学方程, 且具有更加宽泛的pH适应范围(pH=3~8), 同时, CNTs/FeS类Fenton催化剂在使用寿命方面也具有一定的优势. 相似文献