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971.
972.
973.
Intercalationchemistryoflayeredtransitionmetaldisulfideshasbeenextensivelystudiedinthepastyears[1].Ithasbeenestablishedthattheintercalationreactiondependsstronglyonelectronicstructureofthetransitionmetaldisulfides.Forinstance,variousguestmoleculeshavebe…  相似文献   
974.
The electrical behavior of the cationic, polyacetylene-based, conjugated ionomer, poly[(2-cyclooctatetraenylethyl)trimethylammonium trifluoromethanesulfonate], sandwiched between gold electrodes is reported. The steady-state current of this mixed ionically/electronically conducting system is assigned to be unipolar diffusive hole transport for voltages below approximately 1.4 V, giving way to bipolar migratory transport above approximately 1.4 V. In the low-voltage regime, a non-Faradaically controlled doping model is proposed where p-doping at the anode is balanced by the charging of an ionic double layer at the cathode. In the high-voltage regime, n- and p-type regions extend from the electrodes as the voltage becomes sufficient to drive disproportionation and the electric field required by the redistribution of ions begins to substantially influence carrier transport. The assignment of a transport mechanism is primarily based on analyzing the decay of the steady-state system under short-circuit and open-circuit conditions. First, it is shown that the power describing the power-law decay of the short-circuit current is characteristic of the steady-state carrier profile. Second, it is argued that a component of the time-dependent, open-circuit voltage decaying more rapidly than the time scale for ion motion is indicative of a substantial migratory component to steady-state transport, as observed in the high-voltage regime. The hole and electron mobilities are estimated to be on the order of 10(-7)-10(-6) cm(2) V(-1) s(-1).  相似文献   
975.
The enthalpy changes, entropy changes and equilibrium constants of coordination reactions of 18-crown-6 with the alkali ions Na+ and K+ at 298.15K were measured by using RD-496 microcalorimeter with methanol, ethanol, n-propanol and n-butanol as solvents respectively. The results indicated that the enthalpy changes △rHm, entropy changes △rSm, and the stability of the complexes are closely related with the polarity of the solvents, and the order of the stability is ethanol>methanol>n-propanol>n-butanol>H2O for the same complex in the solvents investigated. The stability order was reasonably explained by relating the stability constants of the complexes with the dielectric constants of these solvents, and by using the model of solvated-desolvated ions and ion pair in the coordination reactions.  相似文献   
976.
混合金属配合物MoS4Cu2(NC5H5)4的合成、晶体结构和成键特点   总被引:2,自引:0,他引:2  
混合金属配合物MoS4Cu2(NC5H5)4(NC5H5=吡啶)的晶体属于三斜晶系P1空间群,晶胞参数:a=9.465(50),b=9.463(4),c=14.053(3)Å,α=95.16(3),β=84.89(3),γ=95.91(4)°,Z=2,V=1243(2)Å3;Mr=667.7,Dc=1.784g·cm-3.R因子为0.039,加权Rw因子为0.045.该配合物簇骼具有D2d对称性,Mo-Cu间距分别为2.638Å,2.663Å.端配体吡啶与金属原子Cu间的d*反馈在一定程度上增强了Mo—Cu间的相互作用.  相似文献   
977.
低镍甲烷化催化剂中镍和氧化镧的分散研究   总被引:4,自引:0,他引:4  
本文用X射线衍射法(XRD), 透射电镜(TEM), 配合电子衍射对Ni/Al2O3,Ni/γ-Al_2O_3-La_2O_3等催化剂中镍晶粒度和La_2O_3的分散状态进行了测量和讨论。用透射电镜测量了不同La_2O_3含量的催化剂中镍晶粒度分布, 其平均直径可与X射线宽化法测定值相比较。催化剂中随La_2O_3加入量的增加, Ni晶粒有细化趋势, 从而提高了甲烷化催化活性。对La_2O_3在γ-Al_2O_3表面作密置单层分散的模型提出了新的旁证, 并推断由于La_2O_3在γ-Al_2O_3表面高分散并产生较强相互作用, 使γ-Al_2O_3接近表层晶格发生畸变。  相似文献   
978.
Papers on braid theory and some of its generalization and applications, reviewed in Referativnyi Zhurnal Matematika during 1953–1977, as well as individual papers on an earlier period, are surveyed.Translated from Itogi Nauki i Tekhniki, Algebra, Topologiya, Geometriya, Vol. 17, pp. 159–227, 1979.  相似文献   
979.
In p.32 of [1] the following problem is posed: A problem on Peano mapping Let R be the set of positive rational integers with usual operation a+b≡s(a,b) and a·b≡m(a,b). Every one-to-one(Peano) mapping c=p(a,b) on R×R to all R may serve so associate with s(a,b) and m(a,b) two functions σand μ on R to R by the definitions σ(c)=σ(p(a,b))= s(a,b), and μ(c)=μ(p(a,b))= m(a,b). Does there exist a Peano mapping p(a,b) such that "addition commutes with multiplication" in the sense that σ(μ(c))=μ(σ(c))for all c of R? To illustrate, we note  相似文献   
980.
Cao XN  Lin L  Zhou YY  Shi GY  Zhang W  Yamamoto K  Jin LT 《Talanta》2003,60(5):1063-1070
In this paper, multi-wall carbon nanotubes fuctionalized with carboxylic groups modified electrode (MWNT-COOH CME) was fabricated. This chemically modified electrode (CME) can be used as the working electrode in the liquid chromatography for the determination of 6-mercaptopurine (6-MP). The results indicate that the CME exhibits efficiently electrocatalytic oxidation for 6-MP with relatively high sensitivity, stability and long-life. The peak currents of 6-MP are linear to its concentrations ranging from 4.0×10−7 to 1.0×10−4 mol l−1 with the calculated detection limit (S/N=3) of 2.0×10−7 mol l−1. Coupled with microdialysis, the method has been successfully applied to the pharmacokinetic study of 6-MP in rabbit blood. This method provides a fast, sensible and simple technique for the pharmacokinetic study of 6-MP in vivo.  相似文献   
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