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61.
62.
A large specific surface area perovskite-type mixed oxide PbTiO3 supported cupric oxide was synthesized as a catalyst for NO decomposition and characterized by techniques such as XPS, XRD, H2-TPR before and after NO decomposition reactions. The catalytic properties were tested with a fix-bed micro-reactor. The results showed that the PbTiO3 was inactive for the reactions, but 1wt % Cu/PbTiO3 catalyst gave fairly good activities for NO decomposition at temperature as low as 473 K. Copper species were found well-dispersed but weakly interacted with the support before NO decomposition, and the NO decomposition caused significant change in the environment of the copper species, which became Cu(Ⅰ) and most probably incorporated into surface crystal lattice of the nano-sized PbTiO3. In NO reaction, a large amount of oxygen atoms from the decomposition of NO penetrated into the nano-sized PbTiO3 support and caused small expansion of crystal lattice. The transport of oxygen between the copper species and the catalyst support may be helpful to speed up the kinetic regeneration of active metal sites from oxygen occupancy and resulted in good catalytic performance. 相似文献
63.
Using the total human/mouse DNA as the probe, screening has been carried out three times with in situ plaque hybridization to obtain the single-copy DNA sequence from the human X chromosome genomic library. The effective rate of screening is 1. 45%. DNAs from clones containing single-copy inserts have been analyzed by a panel of hybrid cells with or without human X chromosome. Three segments, designated by DXFD52,73,75, are mapped to the X chromosome. DXFD52 has been precisely localized on Xq12-q13 with in situ chromosomal hybridization. DXFD52 has been partially sequenced. The results indicate that DXFD52 is a new isolated single-copy segment on the X chromosome. Great progress in the RFLPs study with DXFD52 has been achieved in the population of Chongqing, Sichuan Province. The results show that the DXFD52 can be used to detect the RFLP with Hind Ⅲ, Bgl Ⅱ, and Hinf Ⅰ. DXFD52 will be a potential "landmark" for the construction of the complete linkage map of human genome and the analysis of genomic s 相似文献
64.
Effect of microcrystallite preparation conditions on the formation of colloid crystals of cellulose 总被引:7,自引:0,他引:7
Stable colloidal suspensions of cellulose microcrystallites may be prepared from filter paper by sulfuric acid hydrolysis. Above a critical concentration, the suspensions form a chiral nematic ordered phase, or colloid crystal. The preparation conditions govern the properties of the individual cellulose microcrystallites, and hence the liquid crystalline phase separation of the cellulose suspensions. The particle properties and the phase separation of the suspensions were strongly dependent on the hydrolysis temperature and time, and on the intensity of the ultrasonic irradiation used to disperse the particles. The particle size of the microcrystallites was characterized with transmission electron microscopy and photon correlation spectroscopy. The surface charge was determined by conductometric titration. It was possible to fractionate the microcrystallites by size using the partitioning between isotropic and liquid crystalline phases; the longer microcrystallites migrate to the liquid crystalline phase 相似文献
65.
在合成[Co(bpma)(tn)Cl]2+体系配合物的实验中,得到[Co(ptma)(amp)Cl]2+体系的一反式(ptma中仲胺上的氢相对于Cl)经式异构体(m3[ZnCl4]·0.5H2O),其中bpma=N,N′-二(2-吡啶基甲基)胺,tn=1,3丙二胺,ptma=N-(2-吡啶基甲基)丙二胺,amp=2-(氨基甲基)吡啶。此配合物异构体构型选择性形成的原因可能主要是其结构中配体间C-H…π相互作用使之更稳定的结果。利用单晶X-射线衍射法测定的晶体学参数:单斜晶系,空间群C2/c,a=1.55978(19)nm,b=1.33324(16)nm,c=2.2077(3)nm,β=94.832(3)°,V=4.5748(10)nm3,Dc=1.696g·cm-3,Z=8,F000=2360,μ(MoKα)=23.72cm-1,R=0.0475,Rw=0.1204。配合物离子中Co3+为六配位。晶胞中含8个配合物阳离子,8个[ZnCl4]2-阴离子及4个水分子,对映体的比例为1∶1。 相似文献
66.
薛光荣 《分析测试技术与仪器》2004,10(3):176-179
运用了N2O—C2H2火焰原子吸收光谱法进行羰基镍粉钼含量的测定。介绍了钼最佳测定条件及呈良好线性范围的浓度,同时对样品消化处理条件及在测定中样品的干扰因素进行了综合考虑.该方法的相对标准偏差均小于1.0%(n=6),回收率均在97.0%~102.0%(n=6)之间.达到了实验室分析质量控制的要求. 相似文献
67.
XUE Zhixin YANG Guipeng CHEN Dianbao MA Xiaomei ZHANG Xiqin QUAN Zhenlan 《反应性高分子(英文版)》2006,15(1):35-39
Fullerenes (C60/C70) linked up to Ni-doped ZnS through the medium of an amphalic polymer polyvinyl pyrrolidone (PVP) to form a new kind of photocatalyst for hydrogen evolution from aqueous Na2S/Na2SO3 solution under visible light irradiation, the photocatalytic activities of this novel photocatalyst C60/C70-PVP-Zn0.999Ni0.001S are 3-5 fold higher compared with that of precurse catalyst Zn0.999Ni0.001S. This result could be attributed to Schottky barrier layer built between C60/C70 and Zn0.999Ni0.001S due to the electro-negativity of C60 and characteristic of being used as a multiple electron acceptor. C60 or C60/C70, its moiety, with its low energy first excited singlet state, is a good energy acceptor and in addition readily accepts multiple electrons, making it a potential electron accumulate as we know, which could protect the separation between electrons and holes against combination. This is an important reason for the marked increase of amount of H2 evolution during the photocatalytic process for the composite system C60/C70-PVP-Zn0.999Ni0.001S. 相似文献
68.
The atom transfer radical polymerization(ARP)of (-)-menthyl methacrylatc((-)-MnMA) mediated by CuCl/bipyridine and ethy1 2-bromopropionate or 1-phenylethyl bromide in THF system has been studied.The dependence of the specific rotation on molecular weight and the CD of Poly((-)-MnMA) thus obatined was investigated. 相似文献
69.
将天然聚合物壳聚糖(CS)涂覆在介孔分子筛MCM-48表面制得CS-MCM-48复合载体,控制CS与介孔分子筛MCM-48质量比为1∶10时,CS-MCM-48的比表面积、平均孔径和孔容分别为408 m2/g、2.14 nm和0.38 cm3/g.在磷酸盐缓冲溶液-异辛烷混合溶剂中制备了固定化假单胞菌脂肪酶(Pseudomonas CepaciaLipase,PSL)PSL/CS-MCM-48,并用于潜手性苯乙酮一锅法还原转酯化手性拆分反应.结果表明,PSL/CS-MCM-48的催化活性和对映选择性均明显优于纯介孔分子筛MCM-48和壳聚糖制备的固定化酶PSL/MCM-48和PSL/CS.甲苯作溶剂,反应温度为40℃时,底物1-苯乙醇转化率达15.3%,产物(R)-乙酸苯乙酯和(S)-1-苯乙醇的对映体过量值分别为99%和18.0%,对映选择性参数E值达237,固定化酶PSL/CS-MCM-48显示出良好的手性拆分性能. 相似文献
70.
薛光荣 《分析测试技术与仪器》2005,11(2):117-119
采用了N2O-C2H2火焰原子吸收光谱法测定不锈钢材料中钛.介绍钛的最佳测定条件以及线性范围的浓度.在样品测定中对干扰因素进行了综合考虑.实验表明:该方法灵敏度高、干扰小、选择性好、操作简便、容易掌握、分析周期短等优点.测定样品钛1.0~60.0mg/L时,其相对标准偏差均小于1.0%(n=6).标准加入回收率均为97.00-100.0%(n=6)之间.该方法用于不锈钢材料中钛的测定,结果满意。 相似文献