网络环境下基于价值理论的我国消费者购买意愿影响因素研究

随着网上零售业快速发展,如何提高网络消费者购买意愿已成为人们关注的焦点。论文运用感知价值理论分析了网络消费者购买意愿影响因素,提出了影响网络消费者购买意愿的重要研究假设,构建了网络消费者购买意愿假设模型,采用结构方程模型方法对样本数据进行了定量研究。研究结果揭示了网络消费者的风险态度通过感知利益和感知风险对感知价值的间接影响,而感知价值与购买意愿显著正相关。最后,论文对研究结果进行了讨论,提出了促进我国网上零售业发展的建议.     

Banach代数中有限序列的多项式谱(英文)

In this paper,we discuss that the polynomial spectrum,relative spectrum and Spectrum of a Pair of Elements are all compact,so their resolvent sets are all open.     

用实验方法探讨检流计偏转格数与电桥灵敏度的关系

由电桥灵敏度的定义可知,△n是对应于待测电阻的相对改变量,而引起检流计中的偏转量,所以电桥灵敏度越大,对电桥平衡的判断就越容易准确,测量结果也更准确.那么用实验方法测定电桥灵敏度时,△n取值是多少格合适?本文用实验方法探讨了检流计偏转格数与电桥灵敏度的关系.     

Controlled synthesis of Sb<Subscript>2</Subscript>O<Subscript>3</Subscript> nanoparticles by chemical reducing method in ethylene glycol

Antimony trioxide (Sb₂O₃) nanoparticles with particle size range from 2 to 12 nm were successfully synthesized by chemical reducing method. Antimony trichloride was reduced by hydrazine with the presence of sodium hydroxide (NaOH) as catalyst in ethylene glycol at 120 °C for 1 h. Effects of hydrazine concentration ([N₂H₅OH]/[Sb³⁺] = 0.75, 5, 10, 20, and 30, when concentration of NaOH was fixed [NaOH]/[Sb³⁺] = 3) and NaOH concentration ([NaOH]/[Sb³⁺] = 0, 1, 3, and 5, when concentration of hydrazine was fixed [N₂H₅OH]/[Sb³⁺] = 10) on the particle size and shape of the Sb₂O₃ nanoparticles were investigated. Transmission electron microscope, selected area electron diffraction pattern, and high resolution electron microscope were employed to study the morphology and crystallinity of the nanoparticles. It was observed that the particle size decreased and remained constant when [N₂H₅OH]/[Sb³⁺]) ≥ 10 and [NaOH]/[Sb³⁺] = 3. Further study on the crystallinity and phase of the nanoparticles was assisted by X-ray diffractometer (XRD). XRD revealed a cubic phase of Sb₂O₃ (ICDD file no. 00-043-1071) with preferred plane of (622) and lattice spacing of 1.68 Å. Correlation between UV–visible absorption wavelengths of the nanoparticles and their sizes was established.     

Sensitivity Study of Simulation Parameters Controlling CO<Subscript>2</Subscript> Trapping Mechanisms in Saline Formations

The primary purpose of this study is to understand quantitative characteristics of mobile, residual, and dissolved CO₂ trapping mechanisms within ranges of systematic variations in different geologic and hydrologic parameters. For this purpose, we conducted an extensive suite of numerical simulations to evaluate the sensitivities included in these parameters. We generated two-dimensional numerical models representing subsurface porous media with various permutations of vertical and horizontal permeability (k _v and k _h), porosity (f{\phi}), maximum residual CO₂ saturation (S_gr^max{S_{\rm gr}^{\max}}), and brine density (ρ _br). Simulation results indicate that residual CO₂ trapping increases proportionally to k_v, k_h, S_gr^max{k_{\rm v}, k_{\rm h}, S_{\rm gr}^{\max}} and ρ _br but is inversely proportional to f.{\phi.} In addition, the amount of dissolution-trapped CO₂ increases with k _v and k _h, but does not vary with f{\phi } , and decreases with S_gr^max{S_{\rm gr}^{\max}} and ρ _br. Additionally, the distance of buoyancy-driven CO₂ migration increases proportionally to k _v and ρ _br only and is inversely proportional to k_h, f{k_{\rm h}, \phi } , and S_gr^max{S_{\rm gr}^{\max}} . These complex behaviors occur because the chosen sensitivity parameters perturb the distances of vertical and horizontal CO₂ plume migration, pore volume size, and fraction of trapped CO₂ in both pores and formation fluids. Finally, in an effort to characterize complex relationships among residual CO₂ trapping and buoyancy-driven CO₂ migration, we quantified three characteristic zones. Zone I, expressing the variations of S_gr^max{S_{\rm gr}^{\max}} and k _h, represents the optimized conditions for geologic CO₂ sequestration. Zone II, showing the variation of f{\phi} , would be preferred for secure CO₂ sequestration since CO₂ has less potential to escape from the target formation. In zone III, both residual CO₂ trapping and buoyancy-driven migration distance increase with k _v and ρ _br.     

粉末压片X射线荧光光谱法测定铌铁合金中 铁、铌、硅、铝、磷

为提高铌铁合金检验效率,替代繁琐的化学湿法分析,采用粉末压片制样,利用X荧光光谱法对铌铁合金中Fe、Nb、Si、Al、P 5种主要成分进行测定。选用定值过的生产样品作为内控标准样品,主要研究制样细节对分析结果的影响,确认合适的试样粒度和压片参数,通过曲线拟合建立校准曲线。测定结果与化学湿法和电感耦合等离子体原子发射光谱法测定结果比较,各组分精密度相对标准偏差为0.48%～1.9%,准确度满足国标分析要求。     

Sequential Ir‐Catalyzed Allylation/2‐aza‐Cope Rearrangement Strategy for the Construction of Chiral Homoallylic Amines†

Sequential Ir‐catalyzed asymmetric allylation/2‐aza‐Cope rearrangement of arylidene aminomalonates with allylic carbonates was successfully developed, and a variety of enantioenriched homoallylic amine derivatives were obtained in high yields with good chirality transfer and excellent E/Z‐geometry control (up to 99% yield, 96% ee). Compared with previous dual catalytic system established for this transformation, the current mono metal catalytic system provides a simpler and more practical protocol employing the readily available starting materials.     

Thiophenylazobenzene: An Alternative Photoisomerization Controlled by Lone‐Pair⋅⋅⋅π Interaction

Azoheteroarene photoswitches have attracted attention due to their unique properties. We present the stationary photochromism and ultrafast photoisomerization mechanism of thiophenylazobenzene (TphAB). It demonstrates impressive fatigue resistance and photoisomerization efficiency, and shows favorably separated (E)‐ and (Z)‐isomer absorption bands, allowing for highly selective photoconversion. The (Z)‐isomer of TphAB adopts an unusual orthogonal geometry where the thiophenyl group is perfectly perpendicular to the phenyl group. This geometry is stabilized by a rare lone‐pair???π interaction between the S atom and the phenyl group. The photoisomerization of TphAB occurs on the sub‐ps to ps timescale and is governed by this interaction. Therefore, the adoption and disruption of the orthogonal geometry requires significant movement along the inversion reaction coordinates (CNN and NNC angles). Our results establish TphAB as an excellent photoswitch with versatile properties that expand the application possibilities of AB derivatives.     

Sequential Chemistry Toward Core–Shell Structured Metal Sulfides as Stable and Highly Efficient Visible‐Light Photocatalysts

A universal sequential synthesis strategy in aqueous solution is presented for highly uniform core–shell structured photocatalysts, which consist of a metal sulfide light absorber core and a metal sulfide co‐catalyst shell. We show that the sequential chemistry can drive the formation of unique core–shell structures controlled by the constant of solubility product of metal sulfides. A variety of metal sulfide core–shell structures have been demonstrated, including CdS@CoS_x, CdS@MnS_x, CdS@NiS_x, CdS@ZnS_x, CuS@CdS, and more complexed CdS@ZnS_x@CoS_x. The obtained strawberry‐like CdS@CoS_x core–shell structures exhibit a high photocatalytic H₂ production activity of 3.92 mmol h^?1 and an impressive apparent quantum efficiency of 67.3 % at 420 nm, which is much better than that of pure CdS nanoballs (0.28 mmol h^?1), CdS/CoS_x composites (0.57 mmol h^?1), and 5 %wt Pt‐loaded CdS photocatalysts (1.84 mmol h^?1).     

PETPP／Rh配合物催化剂的原位红光外光谱研究

利用原位红外光谱,考察了PETPP/Rh催化剂在CO/H2气氛下的活化情况,并监测1-十二碳烯氢甲酰化的反应过程。实验结果表明,在PETPP/Rh配合物催化剂中,膦配体主要以配位数少的形式存在,因而氢甲酰化反应产物醛的正/异比较低。