代际流动性的地区差异及影响因素—来自中国的微观证据

代际流动性是测度社会不平等的重要指标,区域发展不平衡则是中国的客观现实。运用人口普查数据和中国城市年鉴,可发现中国现阶段代际流动性的三个特征：（1）全国层面的代际收入弹性为0.673。（2）代际流动性呈现出显著的地区及城市差异,沿海、北方的代际流动性明显高于内陆及南方。代际收入弹性最低的省会城市是天津（0.107）,最高的是江西南昌（0.686）;地级市分别是山东莱芜（0.124）和云南丽江（0.76）。（3）具有以下特征的地区具有更高的代际流动性：沿海及经济发达地区,高校更多、中小学教育投入更多的地区,非少数民族聚集地,革命老区。从微观机理上分析代际流动性的地区差异,可以为中国区域平衡发展政策提供理论依据。     

耗散量子隧道系统中的形变效应与热库维数的关系

本文利用微扰及变分法研究了耗散量子隧道系统中热库声子波函数的形变效应,发现形变与热库的维数有关。随着维数降低,一方面形变效应增大,另一方面形变效应对量子隧道系统的影响变得更为显著。 关键词：     

黄原胶以三价铬交联的水凝胶的脱水行为

对黄原胶／三价铬水凝胶在７０，８０和９０℃下的脱水行为进行了研究．脱水与凝胶的交联密度即参与交联反应的三价铬的含量有密切联系．突发脱水之后的过程可以用一级反应动力学描述，反应速度常数随三价铬的浓度和温度的增高而增大，活化能为３４．５ｋｃａｌ／ｍｏｌ．一价盐（ＮａＣｌ）的含量对脱水过程没有影响．     

4fN-15d组态自旋允许与禁戒跃迁能级的研究

通过稀土光谱理论，计算了三价稀土离子的4f^N-15d组态能级的f与d电子间的库仑相互作用，结果表明对于重稀土元素，其自旋允许跃迁能级位置高于自旋禁戒跃迁能级位置，并且两种能级间的能级差随f电子数的增加而依次减小。对于轻稀土元素,则自旋禁戒跃迁能级位置高于自旋允许跃迁能级位置。结果很好地解释了自旋禁戒跃迁能级的光谱现象。     

Synthesis and Crystal Structure of (E)-Ethyl (9-bromo-5-oxo-4-phenyl-1,10b-dihydro-5H-pyrano [3,4-c] chromen-2-ylidene) Acetate

The crystal structure of the title compound (C22H17BrO5 , Mr = 441.27) has been determined by single-crystal X-ray diffraction. The crystal is of orthorhombic system, space group Pna21 with a = 11.76(1), b = 14.58(1), c = 11.52(1), V = 1973.93 , Z = 4, Dc = 1.485 g/cm3 , F(000) = 896, μ(MoKα) = 2.113 mm-1 , the final R = 0.0394 and wR = 0.0809 for 3918 observed reflections (Ⅰ > 2 (Ⅰ)). The single-crystal X-ray diffraction data indicate that the C=C bond is in an E-configuration. The intramolecular C(10)-H(10B)···O(4) and intermolecular C(17)-H(17)···O(4) hydrogen bonds contribute to the stability of the structure.     

Study on the Intramolecular Hydrogen Bonds of Dibenzofurans, Xanthones and Anthraquinones with One or Two Positions Substituted by Hydroxyls

<正>The thermodynamic properties of dibenzofurans (DFs), xanthones (XTs) and an- thraquinones (AQs) with one and two positions substituted with hydroxyls in the ideal gas state at 298.15 K and 1.013×10~5 pa were calculated at the B3LYP/6-311G~* level using Gaussian 03 program. The isodesmic reactions were designed to calculate the standard free energy of formation (Δ_fG~e). Three types of hydrogen bonds exist in the three kinds of chemicals and their bond energies were ascertained as 7-15, 15-23 and 49-58 kJ·mol~(-1) respectively by comparing the Δ_fG~e values. Electronic density topology analysis was applied to validate the strength of bond.     

氢化物发生-原子荧光光谱法测定金属镁中痕量铅

样品以盐酸、过氧化氢进行溶解,以铁氰化钾作氧化剂,用氢化物发生-原子荧光光谱法测定金属镁中痕量铅。研究了氢化物发生的介质和酸度、硼氢化钾溶液的浓度、氢氧化钠的浓度、铁氰化钾的浓度对测定结果的影响,确定了最佳的测定条件。同时对仪器的操作参数进行了最佳选择。在最佳条件下,铅浓度在0~20μg/L范围内与荧光强度呈良好的线性关系,相关系数大于0.9995,方法的检出限为0.37μg/L。样品中铅的加标回收率在91%~102.7%之间,相对标准偏差为4.2%。     

三光气与酚制备三氯甲氧基甲酸芳酯研究

研究了不同取代酚与三光气的反应,得到七种未见报道的新化合物,以IR、MS、1H NMR、13C NMR对产物进行了表征,并探索得到合适的反应催化剂、反应物浓度配比、反应时间,讨论了酚上不同取代基对反应的影响,收率在78.5～90.5%之间。     

Trapping and diffusion behaviors of helium at vacancy in iron from first principles

We investigate the structure,trapping,and diffusion behaviors of helium(He) at vacancy in a Fe single crystal using first-principles simulations.Vacancy with more space can provide the lower electron density region for He binding in comparison with intrinsic Fe,causing He to diffuse into the vacancy inner easily.We provide the quantitative microscopic studies related to the atomic-level thermo-kinetic trapping processes.Moreover,such physical viewpoint can be applied to other vacancy-like defects such as vacancy clusters,void and grain boundaries which can open a space with reduced electron density region to increase He binding in metals and metal alloys.     

室温下合成纺锤形貌六方相NaLnF_4(Ln=Nd,Sm,Eu,Gd,Tb)纳米颗粒

室温下合成长250nm,宽100nm的纺锤形貌六方相的NaNdF4。NaEuF4,NaSmF4,NaGdF4和NaTbF4也用同样的方法获得。产物用XRD,TEM,HRTEM,FESEM和PL进行表征。PL光谱显示合成的NaEuF4的激发波长是394nm。NaEuF4有4个特征发射谱带,分别是591,615,650和681nm。