试论中学实施职业指导教育的重要意义

在中学实施职业指导教育,不仅能充分尊重学生的个性发展,而且在帮助学生准确地选择专业或职业方面具有重要的现实意义。在现阶段需要学校教师转变观念,转换角度,在各科教学中渗透职业指导,以推动中学实施职业指导教育的快速发展。     

基于跳数限制的WSNs自适应协作FEC机制

针对无线协作通信的中继选择问题和高可靠性的需求,提出了一种基于跳数限制的无线传感器网络数据传榆的自适应协作FEC差错控制机制．无线传感器网络中,在数据链路层根据FEC能效在不同数据帧长下随通信距离变化的规律,为每一个数据帧选择最佳协作跳数并建立多中继协作FEC机制;网络层根据IPv6数据包头中的跳数限制域值设定协作传输跳数并计算得到当前数据帧所经历的跳数,根据跳数自适应调整FEC参数N．数学分析表明,该机制能够自适应为每一个数据包添加较少的冗余数据同时自适应选择最佳协作传输跳数,与传统FEC相比提供了更优通信性能．     

节能新民居经济评价研究

农村新民居建设是推进社会主义新农村建设的重要内容。代表农村发展的方向。节能新民居的建设应依托地方资源,优选本土化的节能建材、节能技术。此外。应采用建设项目经济评价方法。从投资估算、资金来源、费用效益三方面对节能新民居进行经济评价。为推进农村新民居建设提供技术支持。     

修正狭义相对论

修正狭义相对论下两惯性系的时间关系变为t’=t/(1-β)～(1/2)(β=V/C),用该式表述两惯性系之间的时间关系更为精确。以此为出发点,进而可推导出速度合成公式、质量和速度的关系m=m0/(1-β)～(1/2)(β=V/C)、质量和能量的联系E=△mCV。以此计算出u介子到达海平面的可能性增大。     

高温压电材料的概况及发展趋势

介绍了高温压电材料的研究现状,综述了钙钛矿、钨青铜型、铋层状、碱金属铌酸盐结构体系4种不同压电陶瓷的结构及研究情况,并指出了高居里点压电陶瓷的研究方向和发展趋势。     

中国省域能源绿色发展评价实证研究——以河南省为例

构建包括能源生产结构、能源消费结构、电能替代与清洁能源替代、节能降耗、环境协调性等五个维度的能源绿色评价模型,以河南省为例,运用熵值法对2008-2017年河南省能源绿色发展水平进行测度,表明河南能源绿色发展水平整体上升,电能替代和清洁替代评价值年均增速最快,自2013年后,对河南能源绿色发展贡献度最大;能源生产结构和消费结构评价值提升幅度较小;节能降耗一直是能源绿色发展水平提升的重要支撑,并与环境协调性维度具有较大相关性。     

基于DISLab的两个热学实验设计

本文利用数字化信息实验系统,对大气压影响水的沸点实验和做功改变气体内能两个实验进行了创新设计,实现实验现象与数据显示、图像处理等多模显示同步。学生在实验操作过程中,通过对比实验现象和多模显示内容,能够更加容易地得出相应的实验结论,改变了传统实验中实验现象与数据分析分离的问题。     

Paving the road toward the use of β-Fe2O3 in solar water splitting: Raman identification,phase transformation and strategies for phase stabilization

Although β-Fe₂O₃ has a high theoretical solar-to-hydrogen efficiency because of its narrow band gap, the study of β-Fe₂O₃ photoanodes for water splitting is elusive as a result of their metastable nature. Raman identification of β-Fe₂O₃ is theoretically and experimentally investigated in this study for the first time, thus clarifying the debate about its Raman spectrum in the literature. Phase transformation of β-Fe₂O₃ to α-Fe₂O₃ was found to potentially take place under laser and electron irradiation as well as annealing. Herein, phase transformation of β-Fe₂O₃ to α-Fe₂O₃ was inhibited by introduction of Zr doping, and β-Fe₂O₃ was found to withstand a higher annealing temperature without any phase transformation. The solar water splitting photocurrent of the Zr-doped β-Fe₂O₃ photoanode was increased by 500% compared to that of the pure β-Fe₂O₃ photoanode. Additionally, Zr-doped β-Fe₂O₃ exhibited very good stability during the process of solar water splitting. These results indicate that by improving its thermal stability, metastable β-Fe₂O₃ film is a promising photoanode for solar water splitting.     

A highly alkaline-stable metal oxide@metal–organic framework composite for high-performance electrochemical energy storage

Most metal–organic frameworks (MOFs) hardly maintain their physical and chemical properties after exposure to alkaline aqueous solutions, thus precluding their use as potential electrode materials for electrochemical energy storage devices. Here, we present the design and synthesis of a highly alkaline-stable metal oxide@MOF composite, Co₃O₄ nanocube@Co-MOF (Co₃O₄@Co-MOF), via a controllable and facile one-pot hydrothermal method under highly alkaline conditions. The obtained composite possesses exceptional alkaline stability, retaining its original structure in 3.0 M KOH for at least 15 days. Benefitting from the exceptional alkaline stability, unique structure, and larger surface area, the Co₃O₄@Co-MOF composite shows a specific capacitance as high as 1020 F g⁻¹ at 0.5 A  g⁻¹ and a high cycling stability with only 3.3% decay after 5000 cycles at 5 A g⁻¹. The as-constructed solid-state flexible device exhibits a maximum energy density of 21.6 mWh cm⁻³.     

Superconductivity in chromium nitrides Pr3Cr10-xN11 with strong electron correlations

Exploration of superconductivity in Cr-based compounds has attracted considerable interest because only a few Cr-based superconductors (CrAs, A₂Cr₃As₃ and ACr₃As₃ (A = K, Rb, Cs, Na)) have been discovered so far and they show an unconventional pairing mechanism. We report the discovery of bulk superconductivity at 5.25 K in chromium nitride in Pr₃Cr_10-xN₁₁ with a cubic lattice structure. A relatively large upper critical field of H_c2(0) ∼ 12.6 T is determined, which is larger than the estimated Pauli-paramagnetic pair-breaking magnetic field. The material has a large electronic specific-heat coefficient of 170 mJ K⁻² mol⁻¹—about 10 times larger than that estimated by the electronic structure calculation, which suggests that correlations between 3d electrons are very strong in Pr₃Cr_10-xN₁₁, and thus quantum fluctuations might be involved. Electronic structure calculations show that the density of states at the Fermi energy are contributed predominantly by Cr 3d electrons, implying that the superconductivity results mainly from the condensation of Cr 3d electrons. Pr₃Cr_10-xN₁₁ represents a rare example of possible unconventional superconductivity emerging in a 3D system with strong electron correlations. Nevertheless, clarification of the specific pairing symmetry needs more investigation.