“通信原理”实验课程的改进与探索

通信原理课程的实验教学环节是课程的重要组成部分,合理改进和设计实验课程,是加深学生对课程的理解和提高学生能力的必要手段。本文就当前通信原理实验课程存在的问题和改进方法进行探讨分析,并在教学中加以运用,取得了较好的效果。     

2020春季开学第一课语文教学案例

随着疫情形势的逐渐好转,各行各业相继复工复产,各中小学校也将陆续开学。为了抚慰疫情给孩子们的心灵带来的影响,时值春季,我们选择了毛泽东的《七绝·咏蛙》作为开学后语文教学的第一课。     

Anisotropic fluoride nanocrystals modulated by facet-specific passivation and their disordered surfaces

Rutile-type fluorides have been proven to be active components in the context of emerging antiferr-omagnetic devices. However, controlled synthesis of low-dimensional, in particular two-dimensional (2D), fluorides in a predictable and deterministic manner remains unrealized because of a lack of efficient anisotropic control, which impedes their further development in reduced dimensions. We report here that altered passivation of {110} growing facets can direct the synthesis of rutile-type fluoride nanocrystals into well-defined zero-dimensional (0D) particulates, one-dimensional (1D) rods and 2D sheets in a colloidal approach. The obtained nanocrystals show positive exchange bias and enhanced magnetic transition temperature from the coexistence of long-range antiferromagnetic order and disordered surface spins, making them strong alternatives for flexible magnetic devices and sensors.     

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.     

新教育的历史使命:重建人文精神

近现代的中国由于受新旧价值观念和东西方文明的冲突,以及科学至上主义的影响,人文精神日渐失落,导致个体的人逐渐失去其成其为“人”的精神价值,社会也日益出现道德危机。中华民族迫切需要重建人文精神,人文教育的价值再次凸显。新时期的教育需要将人文精神的教育贯穿在整个教育理念中,树立生命教育观;要建设一支富有人文精神和人文素养的教师队伍,在教育实践中,实现教育目的、教育内容、教育方法和教育评价标准的人本性。新教育承担着重建人文精神的历史使命。     

浅谈数控机床的国产化

我国从1958年开始发展数控技术,到现在已经建立了一定的规模体系.到目前为止我国数控市场大多被国外数控系统占领,本文主要讨论的是国产低价位数控机床、高速高效数控机床和重型数控机床如何占领国内市场.     

现代教育技术在体育教学中的应用

伴随着社会的高速发展,现代教育技术已经有了质的飞跃,现代教育方式、教学思想与教学目标都受到了现代教育技术的影响。本文主要是采用文献资料法、调查法以及思维方法等对现代教育技术对体育教学中的应用进行研究。通过研究现代教育技术对体育教学的优势以及应用得出以下结论,体育教学的借助现代教学技术解决了体育教师边讲解边示范;解决了一些较为复杂技术动作的展示;解决了枯燥单一的传统体育教学模式等。因此,现代教育技术在体育教学中的应用值得体育教师尝试与研究。     

Molecular design revitalizes the low-cost PTV-polymer for highly efficient organic solar cells

Developing photovoltaic materials with simple chemical structures and easy synthesis still remains a major challenge in the industrialization process of organic solar cells (OSCs). Herein, an ester substituted poly(thiophene vinylene) derivative, PTVT-T, was designed and synthesized in very few steps by adopting commercially available raw materials. The ester groups on the thiophene units enable PTVT-T to have a planar and stable conformation. Moreover, PTVT-T presents a wide absorption band and strong aggregation effect in solution, which are the key characteristics needed to realize high performance in non-fullerene-acceptor (NFA)-based OSCs. We then prepared OSCs by blending PTVT-T with three representative fullerene- and NF-based acceptors, PC₇₁BM, IT-4F and BTP-eC9. It was found that PTVT-T can work well with all the acceptors, showing great potential to match new emerging NFAs. Particularly, a remarkable power conversion efficiency of 16.20% is achieved in a PTVT-T:BTP-eC9-based device, which is the highest value among the counterparts based on PTV derivatives. This work demonstrates that PTVT-T shows great potential for the future commercialization of OSCs.     

数字图书馆的数据存储方案研究

本文对DAS、NAS、SAN三种数据存储技术进行了介绍、分析和比较,结合图书馆数字化建设的需求,提出了数据存储系统的实际方案,并对数字图书馆存储技术的发展趋势进行了相应的探讨。