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Density functional theory investigation of carbon monoxide adsorption on the kaolinite(001) surface 下载免费PDF全文
Carbon monoxide(CO) is a gaseous pollutant with adverse effects on human health and the environment. Kaolinite is a natural mineral resource that can be used for different applications, including that it can also be used for retention of pollutant gases. The adsorption behavior of carbon monoxide molecules on the(001) surface of kaolinite was studied systematically by using density-functional theory and supercell models for a range coverage from 0.11 to 1.0 monolayers(ML). The CO adsorbed on the three-fold hollow, two-fold bridge, and one-fold top sites of the kaolinite(001) was tilted with respect to the surface. The strongest adsorbed site of carbon monoxide on the kaolinite(001) surface is the hollow site followed by the bridge and top site. The adsorption energy of CO decreased when increasing the coverage, thus indicating the lower stability of surface adsorption due to the repulsion of neighboring CO molecules. In addition to the adsorption structures and energetics, the lattice relaxation, the electronic density of states, and the different charge distribution have been investigated for different surface coverages. 相似文献
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LIGHT TRACKS IN THE ANISOTROPIC OPTICAL FIBER WITH TWO TYPES OF PARABOLIC REFRACTIVE INDICES 下载免费PDF全文
The light tracks in an anisotropic optical fiber are studied by the optical metric model. The ordinary and extraordinary light tracks are determined by solving the null geodesic equation. In the paraxial approximation the birefringence of the fiber is analyzed. The focusing and defocusing characte ristics of a light beam are described via the geodesic deviation equation 相似文献
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一个图G称为分数(g,f,n)-临界图如果满足从G中删除任意n个顶点,其剩余子图依然存在分数(g,f) 因子.得到分数(g,f,n) 临界图的新韧度条件,指出若t(G)≥〖SX(〗b2-1-Δ+bn〖〗a〖SX)〗,则G是分数(g,f,n) 临界图,其中Δ=b-a.进一步地,给出分数(a,b,n)-临界图的韧度条件. 相似文献
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运用高光谱技术进行植物叶片探测具有快速、无损、高精度等特点,在叶片色素等生化成分含量估算方面应用前景广阔。类胡萝卜素作为叶片中重要光合色素之一,因其在可见光区域与叶绿素的光谱吸收特征存在重叠,且其含量远低于叶绿素,导致利用光谱信息估算叶片类胡萝卜素含量存在困难,国内外少有针对类胡萝卜素含量的植被指数。利用高光谱数据光谱信息丰富的特点,提出一种以波段组合遍历与相关分析为基础,通过多指数协同来构建组合式的植被光谱指数的新方法。在PROSPECT叶片辐射传输模型模拟出大量具有不同生化和生物物理特征的叶片光谱的基础上,成功构建了一种在叶片水平下具有良好稳定性的类胡萝卜素含量估算新指数RVIDNDVI。结果表明,该方法构建的叶片类胡萝卜素光谱指数由两部分组成:由532和405 nm构建的窄波段NDVI(与类胡萝卜素、叶绿素均强相关)和由548和498 nm构建的窄波段NDVI(仅与叶绿素强相关)进行比值组合,能较好消除叶绿素含量对指数的干扰;通过减去对叶片结构高敏感的916 nm处反射率,能消除叶肉结构参数的影响,进一步提高指数的抗干扰能力。该研究得到的指数RVIDNDVI仅对叶片类胡萝卜素具有高敏感性,相关系数达到-0.94,对其进行指数拟合的R2达到0.834 4。经与模拟数据和实测数据的验证,该指数有较好的估算效果。 相似文献
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在含有氯化铜的氯化1-丁基-3-甲基咪唑(BMIC)和乙二醇(EG)体系中研究金属铜的电沉积。 在BMIC中加入EG,分别研究了EG对离子液体BMIC的粘度和电导率的影响,并通过循环伏安法研究了BMIC-CuCl2-EG溶液中Cu(Ⅱ)的电化学行为,考察了乙二醇浓度、温度和扫描速度对Cu(Ⅱ)电化学行为的影响。 结果表明,Cu(Ⅱ)的电还原过程分为两个过程,其中Cu(Ⅱ)/Cu(Ⅰ)是扩散控制下的不可逆过程,Cu(Ⅰ)/Cu是不可逆过程。 计算得出,在343 K时,Cu(Ⅱ)/Cu(Ⅰ)还原过程中的扩散系数D为7.0×10-7 cm2/s,传递系数为0.24。 在Cu膜表面进行了电沉积,获得金属铜颗粒,经扫描电子显微镜观察Cu的电沉积层的形貌发现,在343 K时沉积30 min后,金属铜晶粒致密,将沉积时间延长至2 h后,晶粒呈球状。 相似文献