排序方式: 共有26条查询结果,搜索用时 31 毫秒
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Wang Bin Nong Xu-Hua Zeng Wei-Nv Li Shan-Shan Li Gao-Yu Liu Jing Huang Guo-Lei Zheng Cai-Juan 《Chemistry of Natural Compounds》2022,58(5):812-815
Chemistry of Natural Compounds - A new compound, named penicillquei C (1), and eight known compounds (2–9), were isolated from the fermentation broth of mangrove-derived fungus Penicillium... 相似文献
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Han C Yan SS Lin XL Hu SJ Zhao MW Yao XX Chen YX Liu GL Mei LM 《Journal of computational chemistry》2011,32(7):1298-1302
First-principles calculations of undoped HfO(2) and cobalt-doped HfO(2) have been carried out to study the magnetic properties of the dielectric material. In contrast to previous reports, it was found that the native defects in HfO(2) could not induce strong ferromagnetism. However, the cobalt substituting hafnium is the most stable defect under oxidation condition, and the ferromagnetic (FM) coupling between the cobalt substitutions is favorable in various configurations. We found that the FM coupling is mediated by the threefold-coordinated oxygen atoms in monoclinic HfO(2) and could be further enhanced in electron-rich condition. 相似文献
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Oscillation of coercivity between positive and negative in MnxGe1-x:H ferromagnetic semiconductor films 下载免费PDF全文
Amorphous MnxGe1-x :H ferromagnetic semiconductor films prepared in mixed Ar with 20% H2 by magnetron cosputtering show global ferromagnetism with positive coercivity at low temperatures. With increasing temperature, the coercivity of MnxGe1-x :H films first changes from positive to negative, and then back to positive again, which was not found in the corresponding MnxGe1-x and other ferromagnetic semiconductors before. For Mn0.4Ge0.6 :H film, the inverted Hall loop is also observed at 30 K, which is consistent with the negative coercivity. The negative coercivity is explained by the antiferromagnetic exchange coupling between the H-rich ferromagnetic regions separated by the H-poor non-ferromagnetic spacers. Hydrogenation is a useful method to tune the magnetic properties of MnxGe1-x films for the application in spintronics. 相似文献
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Universal spin-dependent variable range hopping in wide-band-gap oxide ferromagnetic semiconductors 下载免费PDF全文
This paper proposes a universal spin-dependent variable
range hopping theoretical model to describe various experimental
transport phenomena observed in wide-band-gap oxide ferromagnetic
semiconductors with high transition metal concentration. The
contributions of the `hard gap' energy, Coulomb interaction,
correlation energy, and exchange interaction to the electrical
transport are considered in the universal variable range hopping
theoretical model. By fitting the temperature and magnetic field
dependence of the experimental sheet resistance to the theoretical
model, the spin polarization ratio of electrical carriers near the Fermi
level and interactions between electrical carriers can be
obtained. 相似文献
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We prepare 2× (NiFe/CoZnO)/ZnO/(CoZnO/Co)×2 spin valve structures used for spin injection by sputtering and photolithography. In the junctions, the free magnetic layer 2× (NiFe/CoZnO) and the fixed magnetic layer (CoZnO/Co) × 2 are used to realize the spin valve functions in the external switch magnetic field. Since the wide gap semiconductor ZnO layer is located between the two magnetic semiconductor layers CoZnO, the electrical ,spin injection from the magnetic semiconductor CoZnO into the non-magnetic semiconductor ZnO is realized. Based on the measured magnetoresistance and the Schmidt model, the spin polarization ratio in the ZnO semiconductor is deduced to be 11.7% at 90K and 7.0% at room temperature, respectively. 相似文献
7.
Cai-Juan Zheng Guo-Lei Huang Yan Xu Xin-Ming Song Jun Yao Hui Liu 《Natural product research》2016,30(7):821-825
One new benzopyran derivative (2R*,4R*)-3,4-dihydro-5-methoxy-2-methyl-2H-1-benzopyran-4-ol (1), together with five known compounds (2?6), were obtained from the EtOAc extract of the endophytic fungus Penicillium citrinum HL-5126 isolated from the mangrove Brguiera sexangula var. rhynchopetala collected in the South China Sea. Their structures were elucidated by the detailed analysis of comprehensive spectroscopic data. All compounds were evaluated for their antibacterial activities. Compound 6 exhibited potent inhibitory activity against Bacillus subtilis, Bacillus cereus and Micrococcus tetragenus with the same MIC values of 6.94 μM. 相似文献
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利用多种荧光光谱法、紫外光谱法并结合分子模拟等方法,表征了模拟生理条件下一种植物药活性组分考拉维酸(KA)影响人血清白蛋白(HSA)的结构信息.同步荧光及紫外光谱证实考拉维酸的存在影响了HSA的微环境;二维及三维荧光光谱表明考拉维酸可以猝灭HSA的内源荧光,使其构象发生变化.荧光偏振的测定提供了考拉维酸与HSA作用后生成的配合物弛豫时间与聚集特性的信息,揭示KA的存在使HSA的流动性和微粘度发生变化.定量求得不同温度下(298、308和318 K)考拉维酸与HSA作用的键合参数和热力学参数.分子模拟表明考拉维酸键合位点于HSA分子的疏水腔内,并与赖氨酸Lys195和天冬氨酸Asp451形成三个氢键,与HSA的键合模式主要是疏水作用;位点竞争实验证明考拉维酸在HSA亚结构域的位点II位发生作用.另外,获得的相关物理化学参数从分子水平上揭示了考拉维酸与HSA相互作用的机制.结果表明,HSA对考拉维酸有较强的结合能力,提示人血清白蛋白对考拉维酸可起到储存和转运的作用. 相似文献
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基于密度泛函理论和卡里普索结构预测方法,系统研究了V_nB_(8(n+1))~-(n=1-3)团簇的几何结构、电子和光谱特性.首先,利用卡里普索结构预测方法确定了VB_(16)~-的基态结构为高对称性的C_(2v)点群对称结构.在此基态结构基础上,通过堆积的方式优化得到了V_2B_(24)~-和V_3B_(32)~-团簇的基态结构.结果显示,V_2B_(24)~-和V_3B~(32)~-团簇分别拥有高对称性的C_(4h)和D_(8d)点群对称结构.基于上述基态结构,系统分析了不同尺寸团簇的自然布局分布和自然电子组态、Mayer键级和电子局域函数.最后,讨论了不同团簇的红外、拉曼光谱等光谱特性,为过渡金属钒掺杂硼基纳米材料的研究提供理论参考. 相似文献