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共有20条相似文献,以下是第1-20项 搜索用时 312 毫秒

1.  Novel Substitution Reactions of 5-(4-Nitrophenyl)-10,15,20-triphenyl porphyrin with Nucleophilic Reagents  
   SHAO  Zhi-Jun  CHEN  Zhang-Ping  OUYANG  Yan  ZENG  Dan-Li《有机化学》,2004年第24卷第Z1期
   Substitution reactions of 5-(4-nitrophenyl)-10,15,20-triphenylporphyrin (1)and its Ni(Ⅱ) complexe 2 with different nucleophilic reagents were studied for preparing asymmetric porphyrin. The reaction products are different with the nucleophilic reagents changing. Diporphyrin (3) was obtained when compound 1 reacted with sodium phenoxide or diphenoxide ion in DMF solution. Whereas the nitro group was reduced and 5-(4-amino-phenyl)-10,15,20-triphenylporphyrinato Nickel(Ⅱ) (4) was achieved when compound 2 reacted with above nuleophilic reagents in the same condition. The reductive product 5-(4-aminophenyl)-10,15,20-triphenylporphyrin (5) was also achieved when 1 reacted with mercaptoethanol or thiophene and lithium hydroxide. While the nitro group was substituted by cyanide anion and 5-(4-nitrilephenyl)-10,15,20-triphenylporphyrin (6) was achieved when 1 reacted with sodium cyanide.    

2.  Ultra-broad near-infrared emission of Bi-doped SiO2 Al2O3 GeO2 optical fibers  
   吴金东  陈丹平  吴兴坤  邱建荣《中国光学快报(英文版)》,2011年第7期
   Bi-doped SiO 2 –Al 2 O 3 –GeO 2 fiber preforms are prepared by modified chemical vapor deposition (MCVD) and solution doping process. The characteristic spectra of the preforms and fibers are experimentally investigated, and a distinct difference in emission between the two is observed. Under 808-nm excitation, an ultra-broad near-infrared (NIR) emission with full-width at half-maximum (FWHM) of 495 nm is observed in the Bi-doped fiber. This observation, to our knowledge, is the first in this field. The NIR emission consists of two bands, which may be ascribed to the Bi 0 and Bi + species, respectively. This Bi-doped fiber is promising for broadband optical amplification and widely tunable laser.    

3.  The hydrogen sulfate recognition properties of azo-salicylaldehyde schiff base receptors  
   TaiBao Wei   Jun Wang and YouMing Zhang《中国科学B辑(英文版)》,2008年第51卷第11期
   Azo-salicylaldehyde Schiff base-typed receptors containing an acidic H-bond donor moiety were syn-thesized and characterized. The UV-Vis data indicate that these receptors could act as selective col-orimetric sensors for basic anions and acidic species hydrogen sulfate by different color changes in a water-containing medium. The experiment of Brφnsted acid-base reaction by adding the sodium hy-droxide or perchloric acid revealed that the mechanism of recognition of anions might be deprotona-tion/protonation of the OH fragments by interacting with different anions and that the deprotona-tion/protonation process is fully reversible. The deprotonation/protonation of the receptors is respon-sible for the dramatic color change.    

4.  THE STATE OF CHROMIUM (Ⅲ) ION IN AQUEOUS SOLUTION  
   罗勤慧  沈孟长  丁益  任建国  戴安邦《中国科学B辑(英文版)》,1986年第8期
   So far few systematic studies on the hydrolytic polymerization of Cr(Ⅲ) were reported because of inertness of the ion and complication of the process. We studied it in equilibrium by pH method systematically in a wide concentration range (0.0002—0.32 M). The results show that, in the low concentration range, the composition of the polynuclear hydrolysis products may be represented as [Cr_3(OH)_4] (OH)_n (n=1,2,3); in the medium range, the composition of products as Cr[Cr(OH)_2]_n~((3+n))~+ (n=1,2,3); in the high range, the composition of products as Cr[Gr(OH)]_n~((3+2n))~+ (n=1, 2), and in the intermediate range between medium and high range where the hydrolysis system is in a transition state, the composition of products as [Cr_3(OH)_3]~(6+) and [Cr_3(OH)_4]~(5+). The values of hydrolysis constants of the identical species measured in different Cr concentration ranges and calculated by different methods were found in good agreement with each other. A predominance-arca diagram was made by using the hy    

5.  Effects of preparation conditions of Au/FeOx/Al203 catalysts prepared by a modified two-step method on the stability for CO oxidation  
   Xuhua Zou  Jinguang Xu  Shixue Qi  Zhanghuai Suo  Lidun An  Feng Li《天然气化学杂志》,2011年第20卷第1期
   Composite oxide FeO x /Al 2 O 3 -supported gold catalysts were prepared by a modified two-step method. The effects of preparation conditions on the initial catalytic activity and long-time stability were studied for CO oxidation. XRD, XPS and in situ FTIR were employed to investigate the state of FeO x and the species on the catalyst surface. The results showed that Au/FeO x /Al 2 O 3 catalysts prepared by this method exhibited high activity and high stability in a wide pH value range. Calcination pretreatment was proved to be beneficial to improving the activity and stability. The beneficial effects of FeO x acting as a structural promoter could be ascribed to the ability to supply active oxygen species. As the precursor of FeO x , Fe(NO 3 ) 3 is superior to FeCl 3 for obtaining higher stability.    

6.  Surface photovoltage phase spectroscopy study of the photo-induced charge carrier properties of TiO2 nanotube arrays  被引次数:1
   LiPing Chen  TengFeng Xie  DeJun Wang  ZhiYong Fan  TengFei Jiang《中国科学:化学(英文版)》,2012年第55卷第2期
   By using the surface photovoltage(SPV) technique based on a lock-in amplifier,surface states located 3.1 eV below the conduction band of TiO 2 have been detected in TiO 2 nanotube arrays prepared by anodization of titanium foil in fluoride-based ethylene glycol solution.The photo-induced charge transportation behavior of TiO 2 nanotube arrays was also studied by qualitatively analyzing their SPV phase spectra measured under different external bias.When a negative bias was applied,carriers excited from surface states have the same transportation properties as those excited from the valence band;in contrast,when a positive bias was applied,these two kinds of photo-excited carriers exhibit different transportation behavior.    

7.  Theoretical Study of Ethanethiol Adsorption on HZSM-5 Zeolite  
   Renqing Lü《天然气化学杂志》,2005年第14卷第2期
   The density functional theory and the cluster model methods have been employed to investigate the interactions between ethanethiol and HZSM-5 zeolites. Molecular complexes formed by the adsorption of ethanethiol on silanol H3SiOH with two coordination forms, model Bronsted acid sites of zeolite cluster H3Si(OH)Al(OH)2SiH3 interaction with ethanethiol, aluminum species adsorbed ethanethiol have been comparatively studied. Full optimization and frequency analysis of all cluster models have been carried out using B3LYP hybrid method at 3-21G basis level for hydrogen atoms and 6-31G(d) basis set level for silicon, aluminum, oxygen, carbon, and sulfur atoms. The structures and energy changes of different coordination forms of H3Si(OH)Al(OH)2SiH3-ethanethiol, silanol-ethanethiol and Al(OH)3-ethanethiol have been studied. The calculated results showed the nature of interactions was van der Waals force as exhibited by not much change in geometric structures and properties. The preference order of ethanethiol adsorbed on HZSM-5 zeolite may be residual aluminum species, bridging hydroxyl groups and silanol OH groups from the adsorption heat. The adsorbed models of protonized ethanethiol on bridging hydroxyl OH groups and linear hydrogen bonded ethanethiol on bridging OH groups suggested in literature might not exist as revealed by this theoretical calculation. Possible adsorption models were obtained for the first time.    

8.  Raman Spectroscopic Studies on the Complexation and Adsorbed Behaviour of Thiourea  
   Tian Zhongqun 《高等学校化学研究》,1989年第3期
   Raman spectroscopic studies on thiourea (TU) in highly acidic media (e. g. >3 mol/L HC1O4) show that TU as a solution species is protonated through its sulphur atom and forms complex with anions. However, as an adsorbed species, TU is protonated via the nitrogen atom and adsorbed at the silver electrode surface through the sulphur atom. The distinct effects of pH and anions of the solution on the surface enhanced Raman (SER) spectra of TU were investigated. In acidic and neutral solutions, TU is coadsorbed with anions through its NH3 and - NH2 groups respectively.    

9.  Dependence of photocatalytic activity of ZnxCd1-xS quantum dot composition  
   Alice Hospodková    Ladislav Svoboda  Petr Praus《催化学报》,2015年第3期
   Aqueous colloidal dispersions containing ZnxCd1‐xS quantum dots (QDs) of different x compositions were prepared by precipitating zinc and cadmium acetates with sodium sulphide, in the presence of a cet...    

10.  Effect of Reduction Temperature on Hydrofining Performance of Supported Molybdenum Phosphide Catalyst  
   李凤艳  Zhifang Zhao  李庆杰  赵天波  Cuiqing Li  Guida Sun《天然气化学杂志》,2005年第14卷第4期
   A series of supported molybdenum phosphide catalysts were prepared by impregnation method. XRD, TG-DTG, XPS and BET were used to study the phase, compositions and surface areas of the prepared catalysts. A model reactant containing thiophene, pyridine and cyclohexene was used for the measurements of catalytic activities. The effect of reduction temperature on catalytic activities was investigated. The analysis results by XRD and BET are very different when the reduction temperature is changed from 400 to 900 ℃. MoP/γ-Al2O3 catalysts and CoMoP/γ-Al2O3 catalysts prepared at the reduction temperature of 500 ℃ are the most active ones.    

11.  Effect of Micelle Composition on Acidic Drugs Separation BehaVior by Micellar El  
   JianDeLU YanFeiLIN MiaoWANG XiaoYunFU JianWeiYAN《中国化学快报》,2002年第13卷第12期
   Micclar electrokinetic capillary chromatography(MECC) separation of four acidic drugs similar in strueture was studied.Both anionic surfaetant sodium dodeeyl sulfate(SDS)and nonionie surfactant Tween 20 were used to form single micelles and mixed micelles as pseudostationary phases.The effects of the composition of micellar solution on retention behaviors were studied.The results indicate that there is markedly different selectivity among SDS,Tween 20 and the mixed micelles systems.    

12.  Synthesis and Characterization of Self-oscillating P(AA-co-AM)/PEG SemiIPN Hydrogels Based on a p H Oscillator in Closed System  
   任杰《高分子科学》,2014年第32卷第12期
   Various semi-interpenetrating polymer network(semi-IPN) hydrogels composed of pore-forming agent polyethylene glycol(PEG), acrylic acid(AA) and acrylamide(AM) were prepared by using free radical polymerization with a two-step method. The chemical structures of the synthesized hydrogels were characterized by FTIR spectroscopy and the morphologies were studied by scanning electron microscopy(SEM) method. The swelling properties, such as the p Hresponsive behavior, salt sensitivity, oscillatory swelling/de-swelling behaviors in different solutions with various p H values and self-oscillating behaviors in bath p H oscillator were investigated in detail. The results revealed that the prepared hydrogels exhibited high p H sensitivity and excellent salt sensitivity when the p H values of the medium changes from 3.0 and 7.0 and well reversible properties by undergoing a number of swelling/de-swelling recycles. In particular, the hydrogels exhibited self-oscillation behavior in a closed system containing Br O3?-SO32?-Fe(CN)64?-H+. This study may create a new possibility as biomaterial for new self-walking actuators and other devices.    

13.  Structural and Physical Properties of AsxSe100-x Glasses  
   房明磊  许峰  魏文猴  杨志勇《中国物理快报》,2014年第6期
   We prepare the samples of AsxSe100-x glasses with x = 20, 31, 40 and 50, and measure the glass-transition temperatures Tg, the density and elastic, and optical properties of the glasses. The density, elastic constants and third optical nonlinearity coefficient are found to exhibit the maximal values for the As40Se6o composition. Analysis of x-ray photoelectron spectra of these AsxSe100-x glasses indicate that the chemically stoichiometric As40Se60 consists of perfect corner-sharing pyramidal AsSe3/2 units, while the others contain defect bonds such as As-As and Sere. The optical nonlinearity does not correlate with the concentration of Se, contrary to the report by Quemard et al for Ge-Se Masses.    

14.  Template-free synthesis and characterization of K-phillipsite for use in potassium extraction from seawater  
   Jin Hou  Junsheng Yuan  Jia Xu  Yunpeng Fu  Chunxia Meng《Particuology》,2013年第6期
   Kbphillipsite was prepared using a hydrothermal method. Soluble glass and sodium aluminate were used as raw materials in the absence of an organic template. Investigations regarding the K+ ions were con- ducted at room temperature to determine the ion-exchange capacity in the seawater sample and the selectivity coefficient of the mixed K+-Na~ solution. The sample was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersion spectroscopy (EDS). The K+ ion- exchange capacity is 51 mg/g in seawater and the selectivity coefficient is 75.1 in the mixed K+-Na+ solution. The sample has a selectivity preference for K+, and therefore can be used to selectively extract potassium from seawater. The sample composed of Si, Al, K, Na, and O exhibits a cross-like shape and is a typical K-phillipsite structure.    

15.  Promotion of microvasculature formation in alginate composite hydrogels by an immobilized peptide GYIGSRG  
   Lei Guo  Wei Wang  ZhiPing Chen  Rong Zhou  Yuan Liu  Zhi Yuan《中国科学:化学(英文版)》,2012年第55卷第9期
   The ability to create artificial thick tissues is a major tissue engineering problem,requiring the formation of a suitable vascular supply.In this work we examined the ability of inducing angiogenesis in a bioactive hydrogel.GYIGSRG(NH 2-Gly-Tyr-IleGly-Ser-Arg-Gly-COOH,GG) has been conjugated to sodium alginate(ALG) to synthesize a biological active biomaterial ALG-GG.The product was characterized by 1 H NMR,FT-IR and elemental analysis.A series of CaCO 3 /ALG-GG composite hydrogels were prepared by crosslinking ALG-GG with D-glucono-lactone/calcium carbonate(GDL/CaCO 3) in different molar ratios.The mechanical strength and swelling ratio of the composite hydrogels were studied.The results revealed that both of them can be regulated under different preparation conditions.Then,CaCO 3 /ALG-GG composite hydrogel was implanted in vivo to study the ability to induce angiogenesis.The results demonstrated that ALG-GG composited hydrogel can induce angiogenesis significantly compared with non-modified ALG group,and it may be valuable in the development of thick tissue engineering scaffold.    

16.  Synthesis, Characterization of Mesoporous Al-Mg Composite Oxide and Catalytic Performance for Oxyethylation of Fatty Alcohol  
   SONG Wei-ming DENG Qi-gang ZHOU De-rui ZHAO De-feng《高等学校化学研究》,2005年第21卷第5期
   A mesoporous Al-Mg composite oxide with a hexagonal structure was synthesized with aluminium nitrate and magnesium nitrate as the reagents and sodium dodecyl sulfate(SDS) as the template in the presence of ethylenediamine. The XRD, nitrogen adsorption-desorption and TEM studies indicate that the composite has a hexagonal framework structure and an average pore diameter of 2. 6 nm. The TG/DTA spectra indicate that the decomposition and the removal of the occluded surfactant of the sample take place in a range of 230-550 ℃. The mesoporous Al-Mg composite oxide exhibites a highly catalytic activity for the oxyethylation of fatty alcohols. Narrow-range distributed ethoxylates are formed in the presence of the mesoporous Al-Mg composite oxide catalyst. The distribution selectivity coefficient(Cx) is 24 when the mesoporous Al-Mg composite oxide was used as a catalyst for the oxyethylation of octanol and the average adduct degree of ethoxylates is 6. 4.    

17.  Synthesis,Crystal Structure of Cis—dioxo—catecholatotungsten(VI) Complex and Its NMR Studies on the Interaction with ATP  被引次数:1
   鲁晓明 刘顺成 姜凌 毛希安 叶朝晖《中国化学》,2003年第21卷第6期
   Cis-dioxo-catecholatotungsten(VI) complex anion[W^(VI)O2-(OC6H4O)2]^2- was obtained with discrete protonated ethylenediamine (NH2CH2CH2NH3)^ cations by the reaction of tetrabutyl ammonium decatungstate with catechol in the mixed solvent of CH3OH,CH3CN and ethylenediamine,and compared with its molybdenum anaogue [Mo^(V) O2(OC6H4O)2]^3- by crystal structure,UV,EPR,The results of the UV and EPR spectra show that tungsten is less redox active than molybdenum since the molybdenum is reduced from Mo(VI) to Mo(V) but tungsten stays in the original highest oxidized state Mo(VI) when they are crystallized from the solution above.It is worthy to note that [W^(VI)O2(OC6H4O)]^2- shows the same coordination structure as its molybdenum analogue in which the metal center exhibits distorted octahedral coordination geometry with two cis-dioxocatecholate ligands and might have the related coordination structure feature with the cofactor of flavoenzyme because [Mo^(V)O2(OC6H4O)2]^3- presented essentially the same EPR spectra as flavoenzyme.The NMR studies on the interaction of the title complex with ATP reveal that the reduction of W(VI) to W(V) occurs when the title complex is dissolved in D2O and the W(V) is oxidized again when ATP solution is mixed with original solution and the hydrolysis of the catecholato ligand take places at mean time being monitored by ^1H NMR and ^13C NMR spectra.    

18.  Methanation of carbon dioxide on Ni/ZrO2-Al2O3 catalysts:Effects of ZrO2 promoter and preparation method of novel ZrO2-Al2O3 carrier  被引次数:1
   Mengdie Cai  Jie Wen  Wei Chu  Xueqing Cheng  Zejun Li《天然气化学杂志》,2011年第20卷第3期
   The novel nickel-based catalysts with a nickel content of 12 wt% were prepared with the zirconia-alumina composite as the supports. The new carriers, ZrO2 improved alumina, were synthesized by three methods, i.e., impregnation-precipitation, co-precipitation, and impregnation method. The catalytic properties of these catalysts were investigated in the methanation of carbon dioxide, and the samples were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscope (XPS), temperature-programmed reduction (TPR) and temperature-programmed desorption (TPD) techniques. The new catalysts showed higher catalytic activity and better stability than Ni/γ-Al2O3. Furthermore, as a support for new nickel catalyst, the ZrO2-Al2O3 composite prepared by the impregnation-precipitation method was more efficient than the other supports in the methanation of carbon dioxide. The highly dispersed zirconium oxide on the surface of γ-Al2O3 inhibited the formation of nickel aluminate-like phase, which was responsible for the better dispersion of Ni species and easier reduction of NiO species, leading to the enhanced catalytic performance of corresponding catalyst.    

19.  Reforming of CH4 with CO2 over Co/Mγ-Al oxide catalyst  
   Wen-Jia Cai  Lin-Ping Qian  Bin Yue  Xue-Ying Chen  He-Yong He《中国化学快报》,2013年第24卷第9期
   A series of Co/Mg–Al oxide samples,CoMgAl-x(x=(Mg+Co)/Al molar ratio of 1–5),were prepared by the self-combustion method followed by H2reduction.The catalytic performance and stability of the samples were studied in dry reforming of CH4.XRD and H2-TPR characterization results showed that the reduced CoMgAl-x samples mainly consisted of solid solution and spinel phases with cobalt particles.The spinel phases contained Co3O4 and Con Mg1-n Al2O4(0≦n≦1)varying with the(Mg+Co)/Al ratio.The effect of (Mg+Co)/Al molar ratio on the catalytic behavior was investigated in detail and CoMgAl-3 exhibited the highest catalytic activity and stability among the catalysts studied.    

20.  SELECTIVE SEPARATION OF WATER-ETHANOL MIXTURE THROUGH COPOLYMERIC MEMBRANES. I . ACRYLONITRILE AND MALEIC ANHYDRIDE COPOLYMERIC MEMBRANES  
   《Chinese Journal of Reactive Polymers》,1993年第1期
   Acrylonitrile (AN) and maleic anhydride (MA) copolymer has been synthesized by radical polymerization using ammonium persulfate and sodium bisulfite as initiator. The pervaporation properties of the copolymeric membranes prepared have been investigated for the first time. The dependences of pervaporation characteristics on copolymer composition , feed concentration and operating temperature have been studied. In order to improve the separation properties of the copolymeric membranes, the membranes were hydrolyzed with 10 wt% sodium hydroxide or potassium hydroxide aqueous solution. The hydrolyzed membranes containing more than 0. 069 MA mol fraction showed higher tensile strength and separation properties than the original membranes.    

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