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951.
952.
Jun Zhao Shu Hong Guan Xiao Bin Chen Wei Wang Min Ye De An Guo 《中国化学快报》2007,18(11):1316-1318
The biotransformation of bufalin by cell suspension cultures of Platycodon grandiflorus was investigated and two new biotransformed products were obtained,which was 3-epi-telocinobufagin and 3-epi-bufalin-3-O-β-D-glucoside. 相似文献
953.
The γ-substituted β-diketonate 2,4-dioxo-3-pentyl 4-[4-(n-octyloxy)cinnamoyl]oxybenzoate 1 and its pyrazole and isoxazole derivatives (2 and 3 respectively) have been synthesized and characterized by the spectroscopic methods and elemental analysis. The mesogenic properties of these compounds have been studied by polarizing optical microscopy (POM) and differential scanning calorimetry (DSC). A monotropic nematic mesophase was observed for the β-diketonate 1, in contrast, the pyrazole 2 displays an enantiotropic smectic A and isoxazole 3 exhibits an enantiotropic nematic mesophase. The relationship between the structure and liquid crystalline properties has also been discussed. 相似文献
954.
An efficient method has been developed for one-pot three-component coupling reactions of various aldehydes, 1-cyclohexen-2-one, and primary or secondary amines in the presence of a catalytic amount of Yb(OTf)3 under mild conditions to afford the corresponding 2-arylmethyl N-substituted anilines in good yields. In addition, the catalyst was easily recovered and could be reused for at least four cycles without any loss of activity. 相似文献
955.
A synthesized cyclometalated palladium-azo complex was explored as a multifunctional probe for visual detection of SO2, H2S and NH3 in water. In acidic aqueous environment, the sensing solution underwent a sharp color change from poor violet to deep blue when titrated with Na2SO3 standard solution. But the color changed from poor violet to bright yellow when titrated with Na2S standard solution. In basic environment, the sensing solution rapidly changed to magenta when titrated by NH4Cl-NH3 standard buffer solution at high concentration. However, the color of sensing solution changed to blue when titrated by NH4Cl-NH3 standard buffer solution at low concentration although the pH was kept constant during the titration. Different species of these hazardous gases at environmentally relevant concentration levels were differentiated by independent optical signal outputs, and the interference from other inorganic ions commonly existing in water was very small. 相似文献
956.
A new method for the synthesis of azo Schiff an base ligand in which the azo and azomethine groups are coordination sites was developed through a Schiff base precursor. The precursor, N-4-methoxybenzylidene-3-hydroxyphenylamine (SB) derived from 3-aminophenol was regioselectively coupled with a diazonium ion para to the hydroxyl group of the amine component of the Schiff base. The para selectivity was controlled by the directing effect of the hydroxyl group. The ligand and its nickel(Ⅱ) complex were characterized by elemental analyses, IR and UV-Vis spectroscopy. The analytical and spectral data supported the mononuclear formulation of the complex with metal to ligand ratio (M : L = 1 : 2) and suggested a square planar geometry for the complex. 相似文献
957.
YAN Jing-hui ZHANG Hai-yan LI Zhong-tian CAO Jie SONG Li-hong ZHANG Hui-qiu SHI Chun-shan 《高等学校化学研究》2007,23(4):395-398
Nanocrystals of KMgF3 single-doped and codoped with Ce^3+ or/and Yb^3+ were synthesized separately by the mi-croemulsion method. The X-ray diffraction(XRD) patterns were indexed to show that the KMgF3 crystal system was unchanged. The fluorescent spectra of KMgF3: Ce, Yb polycrystal powders were studied and compared with those of the Ce,Yb doped KMgF3 crystals produced using the high-temperature solid phase method. The diffuse reflection spectra and infrared emission of KMgF3: Ce, Yb were investigated. From the results, the authors could confirm that there were charge transfer processes from Ce^3+ to Yb^3+ in both KMgF3: Ce,Yb nanocrystals and polycrystal powders. 相似文献
958.
GHULAM Qadeer NASIM Hasan-rama FAN Zhi-jin 《高等学校化学研究》2007,23(5):533-537
3,5-Dimethoxyhomophthalic acid was synthesized in four steps from 3,5-dimethoxycinnamic acid via a series of reactions including cyclization of 3-(3',5'-dimethoxyphenyl)propionic acid to 5,7-dimethoxy-1-indanone and oxidative decomposition of methyl-2-hydroxy-2-[5,7-dimethyoxy-1-oxo-1H-inden-2(3H)-ylidene]acetate to 3,5-dimethoxyhomophthalic acid.The synthesized compounds were characterized by elemental analysis,IR,1H NMR,and MS.The biological evaluation experiments of 3,5-dimthoxyhomophthalic acid and the related synthesized compounds were also carried out.Naturally occurring biologically active isocoumarins were prepared in a single step by the condensation of the homophthalic acid with appropriate acid chlorides. 相似文献
959.
一类窄带隙芴基共聚物的合成及其在发光二极管和太阳电池中的应用 总被引:1,自引:0,他引:1
基于9,9-二辛基芴(DOF)与窄带隙单体2,3-二甲基-5,8-二噻吩-喹喔啉(DDQ),通过Suzuki偶合反应,合成了一系列无规和交替窄带隙的芴基共聚物(PFO-DDQ),并对它们的紫外-可见吸收光谱、光致发光光谱、电致发光性能和光伏性能进行了初步研究.共聚物在380 nm和490 nm处有两处明显的吸收峰,其中490nm处的吸收强度随着共聚物中窄带隙单元(DDQ)含量的增加而成比例加强.随着共聚物中窄带隙单元(DDQ)含量的增加,电致发光峰值从580 nm红移到了635 nm.基于该类材料的橙红或饱和红色发光二极管最大外量子效率为1.33%,流明效率为1.54 Cd/A.试验中观察到了窄带隙单元的能量陷阱机制.以窄带隙单元含量为30%的聚合物(PFO-DDQ30)为电子给体、PCBM为电子受体所制备的共混体相异质结太阳电池最大能量转换效率为1.18%,开路电压0.9 V,短路电流密度2.66 mA/cm2.光敏曲线覆盖300 nm~700 nm. 相似文献
960.
Al掺杂α-Fe2O3材料的制备、表征和气敏特性 总被引:1,自引:0,他引:1
采用均相沉淀法制备了纯α-Fe2O3(300 ℃煅烧)和Al掺杂α-Fe2O3(300和400 ℃煅烧), 使用SEM, XRD, ICP和红外光谱等手段进行表征, 并利用气敏仪测试无水乙醇和90#汽油在不同条件下对材料的响应性能. 结果表明, 微量Al掺杂不改变α-Fe2O3材料的物相, 但会阻碍晶粒生长, 使颗粒变小及Fe2O3晶格间隙中的铁原子数目增多, 材料的导电率增大, 从而显著提高材料的气敏性能. Al掺杂α-Fe2O3对乙醇的响应性能优于对汽油的响应性能, 在乙醇气氛中, 材料对湿度仍然不敏感. 经400 ℃煅烧的Al掺杂α-Fe2O3稳定性较好, 可作为检测乙醇气体的半导体气敏材料. 相似文献