化学核心素养背景下的元素化合物教学改进

新课标对元素化合物教学提出了新的要求。在调研北京市4所学校元素化合物教学现状的基础上,依据元素化合物认识模型,提出了核心素养背景下的元素化合物的教学关键改进点:师生对话的有效性;进行物质分类及氧化还原的功能化教学。     

~(60)Co γ射线铅的吸收系数测量实验的数据拟合

介绍了计算60 Co的γ射线物质吸收系数的方法.利用NaI(Tl)闪烁晶体探测器测量60 Co元素放射的1.17MeV和1.33MeV两种γ射线的初始强度比,通过数据拟合法和分别测量法测定了铅片对2种γ射线各自的吸收系数,并分别将2种测量单能射线吸收系数的方法得出的结果同标准吸收系数进行了比较,新的数据拟合法优于原来的分别测量法.     

一维光子晶体材料中的光学传输特性

研究了光在一维周期性介电材料中的传播特性,指出传统的高反膜只是光子晶体的一个特例,从而从光子晶体的角度对多层膜系的设计提出了一条新的思路,同时研究了材料的介电常数以及结构与高反带带宽之间的关系。最后通过在多层膜中引入掺杂（中间一层被另一种介质所代替）,得到第一能隙中掺杂模式的频率与掺杂材料的介电常数之间的对应关系,由此提出一种精确测量介质介电常数的方法。     

Optical Tamm States in Dielectric Photonic Crystal Heterostructure

We investigate one-dimensional dielectric photonic crystal and optical Tamm modes formed by superposition of two band gaps and find that this kind of mode can be explained by the single negative materials tunnelling effect. A finite-size dielectric photonic band gap can mimic one kind of effective single negative material and this property sensitively depends on the frequency location in stop-band regions and surface termination and so on. The effective impedance match and effective phase match give the precise position of the optical Tamm mode. Complete transparency via tunnelling is achieved by two opaque media and demonstrates the validity of our approach.     

Effective permittivity and permeability of one-dimensional dielectric photonic crystal within a band gap

We take a finite dielectric photonic crystal as a homogeneous slab and have extracted the effective parameters. Our systematic study shows that the effective permittivity or permeability of dielectric photonic crystal is negative within a band gap region. This means that the band gap might act as ε-negative materials （ENMs） with ε 〈 0 and μ 〉 0, or μ-negative materials （MNMs） with ε 〉 0 and μ 〈 0. Moreover the effective parameters sensitively rely on size, surface termination, symmetry, etc. The effective parameters can be used to design full transmission tunnelling modes and amplify evanescent wave. Several cases are studied and the results show that dielectric photonic band gap can indeed mimic a single negative material （ENM or MNM） under some restrictions.     

金属有机骨架及其复合材料在食品安全检测中的应用北大核心CSCD

食品安全问题严重影响着人类的身体健康,开发高效、便捷、快速的食品安全检测方法十分必要。金属有机骨架材料(MOFs)是一类具有孔径均匀、粒子尺寸可调、比表面积高和热稳定性好等特点的新型多孔配合物,可根据要求针对性合成,已在食品安全检测中广泛应用。MOFs和其他功能材料(离子液体、量子点、石墨烯、磁性纳米粒子、金或银纳米粒子等)组装形成的复合材料,使MOFs在具有原有优点的基础上获得其他材料导电、发光、磁性、催化等优异性能,在传感检测和样品前处理材料方面引起了研究者的广泛关注。系统综述了MOFs及其复合材料作为色谱法的样品前处理材料或传感材料在食品安全检测领域,如农兽药残留、非法添加物、重金属离子和有机污染物以及微生物毒素等检测中的应用进展,并对其发展前景进行了展望(引用文献56篇)。     

Negative Refraction in One-Dimensional Photonic Crystals with Tilted Interface

We investigate the wave propagation through the tilted interface of one-dimensional photonic crystals. Negative refraction can be realized by excitation of the Bloch states in the extended Brillouin zone with suppressed reflection. Equi-frequency surface analysis shows that the positive refraction, negative refraction or birefringence in this configuration can be achieved under a proper incident angle, which is confirmed by finite-difference timedomain simulations. The results may be useful in applications in the new devices based on one-dimensional photonic or optical waveguide arrays.     

用于高性能超级电容器的氮掺杂碳纳米网的制备

以菲为碳源、氨气为氮源,通过一步碳化、活化法成功制得了氮掺杂碳纳米网(NCNs).在800℃下制得的样品(NCN800)具有独特的网状结构、大的比表面积(1567 m2·g-1)和高的原子百分含量(N 4.41％、O 13.71％).归因于这些结构特征,工作电极NCN800在三电极系统中显示出高的比电容(0.05 A·...