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1.
1.格点量子色动力学概述经过多年努力,人们已经成功地将自然界四种基本相互作用(强、弱、电磁、引力)中的前三种统一在量子场论的框架之中,即粒子物理的标准模型(Standard Model,SM)。  相似文献   
2.
电磁打点计时器是中学物理实验中常用的仪器,它是一种磁电式结构的计时设备.由于长期使用,强烈的振动,调节螺丝松动和打点针磨损等情况常常使打点计时器没有工作在最佳状态,频率、周期不稳定,因此必须进行调试.我们在调试过程中利用  相似文献   
3.
We simulate lattice quantum chromodynamics on asymmetric lattices with improved actions,where quenching approximation is used.These lattices have a spatial lattice spacing αs at 0.3 and 0.4 fm,and a temporal lattice spacing αt from 0.14 to 0.08fm.The lattice spacing error due to αs is greatly reduced through improving both quark and gluon actions at a certain level.We find that masses of mesons have weak dependence on both lattice spacings,while the αs and αt dependence for baryons is more significant.With suitable modelling of these dependences,we are able to obtain the nucleon masss in agreement with the experiment.  相似文献   
4.
吴祥雯  张东  吴振华  马建平 《结构化学》2014,33(9):1326-1332
Two new Zn(Ⅱ)-MOFs were synthesized based on an asymmetric Schiff-base ligand LH, which is obtained by the condensation of 5-formyl-8-hydroxyquinoline and 3-pyridinecarboxylic acid hydrazide. In different mixed solvents, we get two new isomorphism compounds, [Zn(L)2]·C4H8O2·2MeOH(1) and [Zn(L)2]·CH2Cl2·2MeOH(2). Compounds 1 and 2 have been characterized by single-crystal X-ray diffraction, elemental analysis and IR. Compound 1 crystallizes in monoclinic, space group P21/c, with a = 13.856(4), b = 14.156(4), c = 9.620(3) , β = 110.167(5)°, V = 1771.3(9) 3, Dc = 1.500 g/cm3, C38H38N8O8 Zn, Mr = 800.13, F(000) = 832, μ(MoKα) = 0.761 mm-1, Z = 2, the final R = 0.0596 and wR = 0.1221 for 2112 observed reflections(I 2σ(I)). Compound 2 belongs to monoclinic, space group P21/c, with a = 13.575(3), b = 14.130(3), c = 9.485(2) , β = 107.908(3)°, V = 1731.2(6) 3, Dc = 1.529 g/cm3, C35H32Cl2N8O6 Zn, Mr = 796.96, F(000) = 820, μ(MoKα) = 0.926 mm-1, Z = 2, the final R = 0.0527 and wR = 0.1395 for 2501 observed reflections(I 2σ(I)). The Zn(Ⅱ) centers in both 1 and 2 display a distorted octahedral coordination geometry. The octahedral Zn(Ⅱ) nodes and L linkages build up 2-D nets consisting of parallelogram-like grids in the ab plane. The neighboring nets stack through hydrogen bonds to generate 3-D rhombic channels. In 1, the 1,4-dioxane and MeOH guests alternatively arrange in the channels and effectively take up the free space; while in 2, the CH2Cl2 guests are arranged in the channels. In addition, the encapsulated MeOH molecules are bonded to the framework by hydrogen bonds.  相似文献   
5.
采用粉末溶胶法和快速层层退火工艺,在Pt/Ti/SiO2/Si基片上制备了钙锶铋钛(CSBT)陶瓷厚膜.研究了纳米晶粉体加入量对钙锶铋钛陶瓷厚膜结构及性能的影响.结果表明:纳米晶粉体加入量在较宽的范围内可以制备出高质量的钙锶铋钛厚膜,厚膜的显微结构及铁电性能对粉末的加入量比较敏感,适当的加入量有利于促使厚膜晶粒的a轴择优取向,从而有利于膜的铁电性能.当粉末加入量为7.5 g/100 mL时,钙锶铋钛陶瓷厚膜晶粒出现a轴择优取向,剩余极化和矫顽场强分别为6.3 μC/cm2和57 kV/cm,具有较高的应用价值.  相似文献   
6.
利用3,5-二(3-吡啶)-4-氨基-1,2,4-三唑(L)配体与Co(Ⅱ)/Cu(Ⅱ)盐室温下反应得到了一维的配位聚合物{[CoL(H2O)4]SO4·H2O}n1)和单核配合物[Cu(hfac)2L2](2,hfac=hexafluoroacetylacetonate)。通过红外、元素分析及X射线单晶衍射等检测手段对所合成的配合物进行了表征。结构研究表明,配合物1中,配体L呈顺式构型,采取双齿配位方式桥联Co(Ⅱ)离子形成一维正弦链状结构,一维链通过多种氢键相互作用连接进一步形成三维网状结构;溶剂水分子和硫酸根阴离子通过氢键连接在框架上。配合物2中,配体L则采取单齿配位方式,与Cu(Ⅱ)离子形成离散型的单核结构,通过多重氢键作用进而连接成三维网状结构。  相似文献   
7.
设计、合成了功能化的4-四硫富瓦烯-2,6-吡嗪吡啶配体(L),并以此为配体合成了具有电活性的配合物[Fe(Ⅱ)(L)2](BF42·2.75CH3CN·0.25CH2Cl21),通过红外、元素分析及X射线单晶衍射等手段对所合成的化合物进行了表征。配体以三齿的方式参与配位,形成离散型的配合物1,该配合物中含有多种非经典氢键和π…π以及S…S作用。此外研究了该配合物的磁性、电化学性质和光谱电化学性质。  相似文献   
8.
The lowest-lying glueballs are investigated in lattice QCD using N_f = 2 clover Wilson fermions on anisotropic lattices. We simulate at two different and relatively heavy quark masses, corresponding to physical pion masses of mπ~938 MeV and 650 MeV. The quark mass dependence of the glueball masses has not been investigated in the present study. Only the gluonic operators built from Wilson loops are utilized in calculating the corresponding correlation functions. In the tensor channel, we obtain the ground state mass to be 2.363(39) GeV and 2.384(67)GeV at mπ~938 MeV and 650 MeV, respectively. In the pseudoscalar channel, when using the gluonic operator whose continuum limit has the form of ∈_ijkTrB_iD_jB_k, we obtain the ground state mass to be 2.573(55) GeV and 2.585(65) GeV at the two pion masses. These results are compatible with the corresponding results in the quenched approximation. In contrast, if we use the topological charge density as field operators for the pseudoscalar, the masses of the lowest state are much lighter(around 1 GeV) and compatible with the expected masses of the flavor singlet qq meson. This indicates that the operator ∈ijk TrBiDjBk and the topological charge density couple rather differently to the glueball states and qq mesons. The observation of the light flavor singlet pseudoscalar meson can be viewed as the manifestation of effects of dynamical quarks. In the scalar channel, the ground state masses extracted from the correlation functions of gluonic operators are determined to be around 1.4-1.5 GeV, which is close to the ground state masses from the correlation functions of the quark bilinear operators. In all cases, the mixing between glueballs and conventional mesons remains to be further clarified in the future.  相似文献   
9.
We design a compact triplexer based on two-dimensional (2D) hexagonal lattice photonic crystals (PCs).A folded directional coupler (FDC) is introduced in the triplexer beside the point-defect micro-cavities and line-defect waveguides.Because of the reflection feedback of the FDC,high channel drop efficiency can be realized and a compact size with the order of micrometers can be maintained.The proposed device is analyzed using the plane wave expansion method,and its transmission characteristics are calculated using the finite-difference time-domain method.The footprint of the triplexer is about 12× 9 μm,and its extinction ratios are less than –20 dB for 1310 nm,approximately –20 dB for 1490 nm,and under –40 dB for 1550 nm,making it a potentially essential device in future fiber-to-the-home networks.  相似文献   
10.
设计、合成了功能化的4-四硫富瓦烯-2,6-吡嗪吡啶配体(L),并以此为配体合成了具有电活性的配合物[Fe(Ⅱ)(L)2](BF42·2.75CH3CN·0.25CH2Cl21),通过红外、元素分析及X射线单晶衍射等手段对所合成的化合物进行了表征。配体以三齿的方式参与配位,形成离散型的配合物1,该配合物中含有多种非经典氢键和ππ以及S…S作用。此外研究了该配合物的磁性、电化学性质和光谱电化学性质。  相似文献   
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