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961.
唐志诚  吕功煊 《化学进展》2007,19(9):1301-1312
直接甲醇燃料电池作为未来清洁的动力能源,由于具有下列优点:操作温度低(<100℃)、燃料易储存和运输、能量效率高、污染低和燃料启动快而受到人们广泛的关注。阳极电催化剂是直接甲醇燃料电池最重要的组成部分。本文综述了近三年来直接甲醇燃料电池阳极电催化剂最新的研究进展,主要对催化剂制备方法、新型碳载体材料、催化剂类型作了详细的评述,展望了未来甲醇电催化氧化催化剂的发展,指出了电催化剂面临的问题。  相似文献   
962.
王琼  唐浩  谢青季  姚守拙 《化学进展》2007,19(2):370-376
电化学表面等离子体共振(electrochemical surface plasmon resonance, ESPR)技术是近年发展起来的、将表面等离子体共振技术与电化学方法联用的一种新方法.本文在阐明ESPR基本原理及其主要联用方法的基础上,对ESPR技术在金属离子定性/定量分析、纳米薄膜原位动力学研究、电化学聚合反应过程研究、ESPR生物传感等方面的应用进行了详细评述,并提出了提高ESPR检测灵敏度、ESPR与其他技术的联用以及测量装置的微型化、自动化是今后ESPR技术的发展方向.  相似文献   
963.
Using velocity map ion imaging technique, the photodissociation of n-C4H9Br in the wavelength range 231–267 nm was studied. The results and our ab initio calculations indicated that the absorption of n-C4H9Br in the investigated region originated from the excitations to the lowest three repulsive states, as assigned as 1A″, 2A′ and 3A′ in Cs symmetry. Dissociations occurred on the PES surfaces of the three states, terminating in C4H9+Br (2P3/2) or C4H9 + Br* (2P1/2) as two channels, and being impacted by an avoided crossing between the PES surfaces of the 2A′ and 3A′ states. The transition dipole to the 1A″ state was perpendicular to the symmetry plane, so perpendicular to the C–Br bond. The transitions to the 3A′ state was polarized parallel to the symmetry plane, and also parallel to the C–Br bond. While the transition dipole to the 2A′ state was in the symmetry plane, but formed an angle of about 53.1° with the C–Br bond. We have also determined the avoided crossing probabilities, which affected the relative fractions of the individual pathways, for the photolysis of n-C4H9Br near 234 nm and 267 nm.  相似文献   
964.
以邻苯二甲醛及3-巯基丙酸为衍生试剂,50mmol/L磷酸缓冲液(pH7.0)-乙腈(94∶6,V/V)为流动相,在LichrosorbRP18(150mm×4.6mmi.d.,5μm)柱上,研究并建立了测定动物肠粘膜中谷氨酰胺(Gln)的柱前衍生荧光RP-HPLC法。样品与衍生剂按4∶1进行衍生反应,Ex=230nm,Em=389nm;流速为2.0mL/min。Gln的保留时间为3.158min,检测限为25μmol/L(S/N=3.5),线性范围为50~3200μmol/L,r=0.9996。  相似文献   
965.
光学显微镜在人们认识微观世界的过程中一直扮演着非常重要的角色.随着认识的深入,对空间分辨率的要求也越来越高.但是众所周知,普通光学显微镜(远场情况下)的分辨率受光的衍射效应所限制,一般可表达为0.61A/N.A.(约等于A/2,A为照射光的波长,N.A.为数值孔径)  相似文献   
966.
At the quantum-chemical level, we characterize some important parameters that control photoelectronic properties of three π-conjugated fluorene-thiophene oligomers namely, 2,7-di(2-thienyl)-9,9-dihexylfluorene, 2,5-Bis-(9H-fluorene-2-yl)-thieno[3,2-b]thiophene and 2,7-Bis[5-(1,1-dicyanovinyl)thiophene-2-yl]-9,9-di-n-hexylfluorene (FTCN). The geometric and electronic structures of these compounds in the ground and the lowest singlet excited states were studied using density function theory. By employing the incoherent transport model, the electron and hole mobilities were evaluated on a wide variety of nearest-neighbor charge transfer pathways. These results show that the chemical modifications by changing linkage mode or introducing the electron-withdrawing group could improve the charge transfer, especially for FTCN. Meanwhile, it is found that the packing effect weakens the emission intensity to some extent according to the simulations of photoluminescences of dimers.  相似文献   
967.
六氯合铂酸钾与金属硫蛋白的体外反应   总被引:1,自引:0,他引:1       下载免费PDF全文
本文报道了K2PtCl6与兔肝Zn7MT-Ⅱ和apoMT-Ⅱ的反应包含一个氧化还原反应和一个取代反应。通过紫外可见光谱、园二向色谱、柱层析和X-光电子能谱研究了该反应的性质、铂在反应产物中的键合位置和氧化态。金属硫蛋白(MT)被氧化成单体、双聚和多聚产物,其中含有分子间和分子内CyS-SCy二硫键。Pt(Ⅳ)被还原成Pt(Ⅱ)然后键合于产物中。随着K2PtCl6与MT的反应摩尔比和反应时间的增加,键合于产物中的Pt(Ⅱ)的计量数增加而蛋白中所含Zn(Ⅱ)的量减少。当Zn7MT与4和超过10摩尔的K2PtCl6反应时,分别得到了Pt4Zn4MT和Pt8MT。当apoMT与7及超过25倍的K2PtCl6在pH 2条件下反应时,分别得到了Pt7MT和Pt15MT。动力学数据表明K2PtCl6与apoMT的反应比与Zn7MT的反应快。  相似文献   
968.
纳米氧化锆的物相与尺寸效应   总被引:14,自引:2,他引:14  
用溶胶凝胶法制得ZrO2粉体。通过控制晶体尺寸得到了室温下稳定的立方相、四方相和单斜相。用X射线衍射(XRD)、透射电镜(TEM)、激光拉曼谱(LRS)、电子顺磁共振(ESR)等技术研究了晶体结构和晶粒尺寸的相互关系。试验表明:单斜相、四方相、立方相ZrO2的比表面能依次递减。因而,当晶粒尺寸减小至纳米级时,四方相和立方相都可变为室温下的稳态或亚稳态。  相似文献   
969.
Interaction of urea with pluronic block copolymers by 1H NMR spectroscopy   总被引:1,自引:0,他引:1  
Solution 1H NMR techniques were used to characterize the interaction of urea with poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO) triblock copolymers. The urea was established to interact selectively with the PEO blocks of the block copolymer, and the interaction sites were found not to change with increasing temperature. Such interactions influence the self-assembly properties of the block copolymer in solution by increasing the hydration of the block copolymers and stabilizing the gauche conformation of the PPO chain. Therefore, urea increases the critical micellization temperature (CMT) values of PEO-PPO-PEO copolymers, and the effect of urea on the CMT is more pronounced for copolymers with higher PEO contents and lower for those with increased contents of PPO segments.  相似文献   
970.
This paper dealt with improving the blood compatibility of the rapamycin-eluting stent by incorporating curcumin. The rapamycin- and rapamycin/curcumin-loaded PLGA (poly(d,l-lactic acid-co-glycolic acid)) coatings were fabricated onto the surface of the stainless steel stents using an ultrasonic atomization spray method. The structure of the coating films was characterized by Fourier transform infrared spectroscopy (FTIR). The optical microscopy and scanning electron microscopy (SEM) images of the drug-eluting stents indicated that the surface of all drug-eluting stents was very smooth and uniform, and there were not webbings and "bridges" between struts. There were not any cracks and delaminations on stent surface after expanded by the angioplasty balloon. The in vitro platelet adhesion and activation were investigated by static platelet adhesion test and GMP140 (P-selection), respectively. The clotting time was examined by activated partially prothromplastin time (APTT) test. The fibrinogen adsorption on the drug-loaded PLGA films was evaluated by enzyme-linked immunosorbent assay (ELISA). All obtained data showed that incorporating curcumin in rapamycin-loaded PLGA coating can significantly decrease platelet adhesion and activation, prolong APTT clotting time as well as decrease the fibrinogen adsorption. All results indicated that incorporating curcumin in rapamycin-eluting coating obviously improve the blood compatibility of rapamycin-eluting stents. It was suggested that it may be possible to develop a drug-eluting stent which had the characteristics of not only good anti-proliferation but also improved anticoagulation.  相似文献   
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