水柏枝属植物的化学成分及生物活性研究进展

水柏枝属(Myricaria)植物全世界有13种,是重要的生态保护、药用和饲用植物.本文对该属植物的化学成分及药理进行综述,并对该属植物的研究提出展望.     

Al对HP40合金室温力学性能的影响

采用中频感应炉熔炼的方法制取样件.用光学显微镜分析在HP40合金中加入质量分数为5%～10%的Al元素时,各质量分数所对应的相组成和显微组织,研究在HP40合金中加入不同质量分数的Al对合金室温力学性能的影响以及合金力学性能与显微组织的关系.结果发现,加Al元素的HP40合金抗拉强度和屈服强度均随Al质量分数的增加而先升高后降低;合金的硬度随Al质量分数的增加而显著提高;合金的延伸率在Al质量分数为5%时,与未加Al的HP40合金一样未降低,而后随着Al质量分数的增加而降低.随着Al质量分数的增加,由于金属间化合物(Ni,Fe)Al的析出,合金的组织也发生了明显的变化,组织由网状结构变为枝状结构和羽毛状结构.     

Visualizing heavy fermions emerging in a quantum critical Kondo lattice

In solids containing elements with f orbitals, the interaction between f-electron spins and those of itinerant electrons leads to the development of low-energy fermionic excitations with a heavy effective mass. These excitations are fundamental to the appearance of unconventional superconductivity and non-Fermi-liquid behaviour observed in actinide- and lanthanide-based compounds. Here we use spectroscopic mapping with the scanning tunnelling microscope to detect the emergence of heavy excitations with lowering of temperature in a prototypical family of cerium-based heavy-fermion compounds. We demonstrate the sensitivity of the tunnelling process to the composite nature of these heavy quasiparticles, which arises from quantum entanglement of itinerant conduction and f electrons. Scattering and interference of the composite quasiparticles is used to resolve their energy-momentum structure and to extract their mass enhancement, which develops with decreasing temperature. The lifetime of the emergent heavy quasiparticles reveals signatures of enhanced scattering and their spectral lineshape shows evidence of energy-temperature scaling. These findings demonstrate that proximity to a quantum critical point results in critical damping of the emergent heavy excitation of our Kondo lattice system.     

Scaling the Kondo lattice

The origin of magnetic order in metals has two extremes: an instability in a liquid of local magnetic moments interacting through conduction electrons, and a spin-density wave instability in a Fermi liquid of itinerant electrons. This dichotomy between 'local-moment' magnetism and 'itinerant-electron' magnetism is reminiscent of the valence bond/molecular orbital dichotomy present in studies of chemical bonding. The class of heavy-electron intermetallic compounds of cerium, ytterbium and various 5f elements bridges the extremes, with itinerant-electron magnetic characteristics at low temperatures that grow out of a high-temperature local-moment state. Describing this transition quantitatively has proved difficult, and one of the main unsolved problems is finding what determines the temperature scale for the evolution of this behaviour. Here we present a simple, semi-quantitative solution to this problem that provides a basic framework for interpreting the physics of heavy-electron materials and offers the prospect of a quantitative determination of the physical origin of their magnetic ordering and superconductivity. It also reveals the difference between the temperature scales that distinguish the conduction electrons' response to a single magnetic impurity and their response to a lattice of local moments, and provides an updated version of the well-known Doniach diagram.     

MoCrFeMnNi高熵合金退火后的组织和性能

高熵合金因具有高强度、耐腐蚀、耐高温氧化等优异的性能而备受关注.采用铝热反应法制备MoCrFeMnNi高熵合金,用XRD、SEM、EDS、显微硬度和压缩实验研究了铸态及700 ℃/12 h、800 ℃/6 h、1 000 ℃/3 h退火后合金的组织和性能变化.结果表明:铝热法制备的MoCrFeMnNi高熵合金为典型的枝晶形貌,晶体结构主要由BCC相、FCC相以及少量的σ相构成,其中枝晶区域为BCC结构,富含Mo和Cr元素;枝晶间区域为FCC结构,富含Ni元素.随着退火温度的上升,枝晶间逐渐析出纳米级σ相,使得合金硬度上升,在800 ℃/6 h退火处理后达到667 HV,抗压强度达到1 050 MPa;1 000 ℃/3 h退火后,σ相团聚成球状和针状并在高温下部分溶解,σ相的减少使得合金硬度下降,抗压强度与铸态时相当,塑性显著提升.     

ERP沙盘模拟对抗课程研究与实践

通过对ERP沙盘模拟对抗课程的研究与实践,针对不同专业学生进行改造和功能拓展.实践证明,该课程可以培养学生系统思考能力,提升学生的全局观念.加强学生的协作精神,树立学生的整体意识.     

混合甲酚异构体的气相色谱法测定

本文提出了一种简便、快速分析混合甲酚中邻—甲酚,间工甲酚,对—甲酚异构体的气相色谱方法。选择实验室常用的SE-30为固定相,该固定相对混合甲酚异构体有良好的选择性。应用于工业中混合甲酚测试,效果理想。     

青海省唐古特铁线莲生物学特性的研究

唐古特铁线莲是青藏高原一种重要的野生药用植物,全草可以入药,其中植株所含的皂甙类化合物具有十分重要的经济价值和药用价值.但由于过渡开采,使得该野生植物资源量呈显著下降趋势,这对于青藏高原的生态环境保护及药用植物的开发利用都是不利的.本文采用野外定点法、和最小样方法分别对青海省唐古特铁线莲的生物学特性和群落数量特征进行研究,旨在为青海省唐古特铁线莲资源的保护和合理开发利用提供科学依据.