排序方式: 共有23条查询结果,搜索用时 17 毫秒
1.
制备了甘氨酸-壳聚糖复合膜修饰玻碳电极(Gly-CTS/GCE),研究了抗坏血酸(AA)和尿酸(UA)在该修饰电极上的电化学行为。结果表明在pH=5.59的磷酸盐缓冲溶液中,AA、UA在Gly-CTS/GCE上均产生灵敏的不可逆氧化峰,其峰电流与浓度在一定范围内呈良好的线性关系。对AA和UA混合溶液平行测定7次,相对标准偏差分别为4.6%、2.9%,表明该电极重现性和稳定性良好。AA、UA在Gly-CTS/GCE电极上的氧化峰峰电位相差340mV,据此可实现对二者的同时检测,并可应用于实际样品测定。 相似文献
2.
Butyl rubber (polyisobutylene-co-isoprene) mixed with polyisobutylene was crosslinked to yield elastomeric macromolecular networks containing dissolved linear macromolecules. Adhesion of these materials to themselves (self-adhesion) and to an inert substrate was investigated over a wide range of peel rates and test temperatures. Greatly enhanced self-adhesion was found when linear polyisobutylene molecules of high molecular weight were present, but the strength of adhesion to a rigid inert substrate was hardly affected. The enhancement of self-adhesion is attributed to interdiffusion of polyisobutylene molecules. It was greatest at intermediate peel rates and temperatures, becoming insignificant at extremely low rates, probably because the diffusing species can then migrate readily, and at high effective rates of peel when the polymer approaches the glassy state and the strength of adhesion is high in all cases. A transition to somewhat lower levels of adhesion at relatively high rates of peel is tentatively ascribed to the onset of molecular fracture in place of pullout. The presence of large amounts of low-molecular-weight polyisobutylene (M?v = 50,000 g/mol) increased the level of self-adhesion and of adhesion to an inert substrate to a similar degree, over a broad range of peel rates. This effect is attributed primarily to enhanced viscous losses in the elastomeric layer during separation. Application of these results to crack and weld-line healing in glassy plastics is discussed. 相似文献
3.
4.
C70X2(X=H,F, Cl)的稳定性和电子光谱 总被引:1,自引:0,他引:1
用INDO方法研究C70H2四种异构体的稳定性, 表明其最稳定异构体为1, 9-C70H2和7, 8-C70H2, 两者能量差为16.3KJ.mol^-^1, 与实验值及ab initio计算值接近; 光谱计算表明, 其特征吸收峰与实验值一致。在此基础上预测C70F2和C70Cl2的稳定性和电子光谱, 表明C70F2四种异构体的稳定性顺序与C70H2一致, 而C70Cl2则以21, 42-异构体最为稳定。二者的电子光谱与C70H2极其相似只是在500nm以上有细微差别。 相似文献
5.
6.
Adhesion of lightly crosslinked sheets of EPDM (ethylene–propylene–diene terpolymer) to themselves and to a Mylar substrate has been investigated over wide ranges of peel rate and test temperature. The effect of incorporating ethylene–propylene copolymer (EPR) before crosslinking, to yield a loose macromolecular network containing dissolved linear EPR macromolecules, was also studied. The self-adhesion of these materials was found to be much greater than their adhesion to Mylar, over a wide range of effective peel rates. This is attributed to interdiffusion of EPR and EPDM molecular strands. At extremely low peel rates the enhancement of adhesion was smaller, probably because of back-diffusion, and at high rates, the strength of adhesion became high in all cases. These results are compared to those obtained previously for polyisobutylene-co- isoprene networks containing linear polyisobutylene molecules. The enhancement of self-adhesion at intermediate rates of peel was considerably greater for the EPDM-based materials, probably because of a lower degree of crosslinking and a greater tendency to form molecular entanglements. 相似文献
7.
8.
Crittall MR Ellul CE Mahon MF Saker O Whittlesey MK 《Dalton transactions (Cambridge, England : 2003)》2008,(32):4209-4211
The first examples of abnormal coordination of Ardeungo's carbene, 1,3-bis-adamantylimidazol-2-ylidene, have been isolated and structurally characterised following reaction of the free carbene with the trinuclear clusters M(3)(CO)(12) (M = Ru, Os). 相似文献
9.
Charles E. Ellul 《Journal of organometallic chemistry》2010,695(1):6-2376
The reduction of trans-[Pd(NHC)2Cl2] (NHC = IMes, 1,3-bis(2,4,6-trimethylphenyl)imidazol-2-ylidene; IiPr2 = 1,3-bis-isopropylimidazol-2-ylidene) with potassium graphite under an atmosphere of CO affords the palladium NHC carbonyl clusters [Pd3(μ-CO)3(NHC)3] (NHC = IMes, 1; IiPr2, 3). Treatment of 1 with SO2 at room temperature yields the bridging SO2 complex [Pd3(μ-SO2)3(IMes)3] (4) in quantitative yield. Complexes 1, 3 and 4 have been structurally characterised by X-ray crystallography. 相似文献
10.
The fracture of thick laminated graphite/epoxy composites has been the subject of an extensive research program. The program
was divided into three major areas of investigation which included laminate thickness, laminate stacking sequence, and part-through
surface flaws. The results from this program are reviewed with emphasis placed on their applicability to the design of thick
laminated composite structures.
Paper was presented at 1985 SEM Spring Conference on Experimental Mechanics held in Las Vegas on June 9–14, 1985. 相似文献