基于不同还原剂体系银粉的可控制备

以硝酸银为原料,在不同温度条件下,分别以无机和有机还原剂,制备了不同形貌的银粉颗粒,采用扫描电子显微镜以及X射线衍射对其形貌与结构进行了表征。在此基础上,重点研究了不同还原体系对银粉颗粒形貌的影响,并提出了相应的机理。研究结果表明,以七水合硫酸亚铁作为还原剂时,银颗粒形貌由铁离子浓度控制,在高浓度,低反应速度条件下可得到花状银颗粒。随着体系浓度的下降,表面由粗糙花状变为光滑球状,导电性能并随之升高。以抗坏血酸作为还原剂,硫酸根为保护剂时,硫酸根浓度对银粉形貌有着很大的影响,随着硫酸根浓度的增加,银颗粒由球形变为枝片状。导电性能有所升高。     

Syntheses,Structures, and Properties of Three Coordination Polymers: [Cd_2(bpp)_(1.5)(Hbpp)(phen)_2]_n, [Mn_3(Htptc)_2(phen)_2(H_2O)_2]_n,and {[Cu(btc)_(0.5)(1,4-bib)]·2H_2O}_n

Hydrothermal reactions of three aromatic polycarboxylic acids and the transitional metal cations in the presence of phen and 1,4-bib afford three new coordination polymers: [Cd2(bpp)1.5(Hbpp)(phen)2]n(1), [Mn3(Htptc)2(phen)2(H2O)2]n(2), and {[Cu(btc)0.5(1,4- bib)]·2H2O}n(3)(H2bpp = 2,6-bis(4'-carboxyphenyl)-4-phenylpyridine, H4tptc = terphenyl-2,5,2',5'-tetracarboxylic acid, H4btc = biphenyl-2,2',4,4'-tetracarboxylic acid, phen = 1,10-phenanthroline, and 1,4-bib = 1,4-bis(1H-imidazol-1-yl)benzene). Their structures have been determined by singlecrystal X-ray diffraction analyses, elemental analyses, IR spectra, and powder X-ray diffraction(PXRD) analyses. In compound 1, the CdII cations are linked by bpp2- to form one ladder structure, based on which a 3D network is constructed with the help of non-covalent interactions. The topology of 2 is a 3D(3,4,5)-connected framework with the Point Schl?fli symbol of(42.6)32(4.62.8)(45.64.8)2. Compound 3 shows an unprecedented 3D(4,4)-connected framework with the Point Schl?fli symbol of(64.82)2(65.8). Moreover, the luminescent property of 1 has been investigated.     

壳聚糖-磷酸二氢胆碱凝胶固定肌红蛋白的直接电化学和电催化

使用壳聚糖和亲水性离子液体磷酸二氢胆碱形成的复合水凝胶固定肌红蛋白(Mb)制备修饰电极。在修饰电极表面,实现了Mb的直接电化学和对O2、H2O2的电催化。同时,该修饰电极表现出了较高的热稳定性。研究表明该新型复合水凝胶具备较好的生物相容性,使膜内的Mb保持了其天然构象和活性,并且很大程度地提高了修饰电极的导电性,促进了Mb和电极之间的电子传递,在直接电化学、生物催化和第三代生物传感器的制备等领域有良好的应用前景。     

气相色谱正构烷烃和直链脂肪酸甲酯两种线性保留指数之间的转换方法

保留指数是气相色谱中用于化合物结构鉴定的重要工具。本研究对基于正构烷烃和直链脂肪酸甲酯的线性保留指数进行线性拟合,发现在所设定的4种不同的升温条件下两种保留指数之间呈现较为固定的线性关系：在弱极性柱（固定液为5%苯基和95%的甲基聚硅氧烷）和极性柱（固定液为聚乙二醇）条件下,正构烷烃保留指数（y）与脂肪酸甲酯保留指数（x）之间的关系分别为y=1.0051x+318.51（r²=1）和y=1.0362x+562.519（r²=1）。采用文献保留指数对所建立的线性关系进行验证,发现通过公式换算得到的保留指数均在其对应文献值的均值加减方差范围内,说明换算公式真实有效。两种保留指数之间关系的建立对于化合物结构鉴定时扩大保留指数搜索范围、减少保留指数测定实验具有重要意义。     

电子在蛋白质分子中的迁移机理及其特性

ATP水解作用所释放的能量能引起蛋白质分子中额外电子的激发,其激发与氨基酸残基晶格畸变相互作用,使额外电子自陷成孤子,这孤子在附着有供体(D)和受体(A)的蛋白质分子中运动时,由于孤子与供体电子的相互作用而"自局域"在孤子上进行迁移,从而可把电子供给受体.使用作者提出的孤子理论研究了这种迁移的特征,计算了在这种非平衡态过程中由孤子迁移电子的速率和动能系数,得到了一些有趣的结果,揭示了这种迁移的本质,求得了迁移的大小.     

Mild Hydrothermal Synthesis, Characterization and Properties of Na_5Ce(PO_4)_3, Na_3Yb_2(PO_4)_3·H_2O and Na_(5-2x)Yb_2xCe_(1-x)(PO_4)_3·yH_2O

IntroductionRare earth phosphates have been widely studied due to their important properties and potential technological application. The early studies of cerium phosphates focused on their inter..esting ion exchange properties, and a series of such compounds was prepared['--']. Rare earthorthophosphates are also regarded as promising phosphors for fluorescent tubes because oftheir luminescence properties["']. Since crystal NdP,O,. was discovered to have efficient laseremi.sion[6'7), the pol…     

米兰花化学成分的GC-MS分析

采用超声波提取米兰花.然后对其化学成分进行GC-MS分析.从米兰花中分离确定了27种主要成分,其中萜类物质含量相对较高.     

CdS/TiO2/漂珠复合光催化剂制备及其降解高效氯氰菊酯研究

采用溶胶-凝胶-浸渍法制备了Cds/TiO2/漂珠复合光催化剂,通过SEM,XRD对其结构进行了表征.以高效氯氰菊酯(BEC)杀虫剂的光催化降解为模型反应,研究了CdS/TiO2/漂珠的光催化性能,探讨了影响催化剂活性的因素及采用太阳光作光源处理BEC的可行性.结果表明,CdS/TiO2/漂珠投加量为3 000mg·L-1,初始浓度为45 mg·L-1、初始pH为6.5,通气量为200 mL·min-1时间为60 min,BEC降解率分别为92.1%(125W高压汞灯)和79.3%(5 W紫外灯),采用太阳光照射300 min,BEC降解率可达93.4%.BEC的降解反应遵从L-H动力学模型,测得反应速率常数9.80 mg·(L·min)-1,吸附常数4.36×10-3 L·mg-1.     

An All-Solid-State Tunable Dual-Wavelength Ti：Sapphire Laser with Quasi-Continuous-Wave Outputs

A high power dual-wavelength Ti：sapphire laser system with wide turning range and high efficiency is described, which consists of two prism-dispersed resonators pumped by an a11-solid-state frequency-doubled Nd：YAG laser. Tunable dual-wavelength outputs, with one wavelength range from 750nm to 795nm and the other from 80Ohm to 850nm, have been demonstrated. With a pump power of 23 W at 532nm, a repetition rate of 6.5kHz and a pulse width of 67.6ns, the maximum dual-wavelength output power of 5.6 W at 785.3nm and 812.1 run, with a pulse width of 17.2ns and a line width of 2nm, has been achieved, leading to an optical-to-optical conversion efficiency of 24.4%.     

Electronic Structures of Wurtzite GaN with Ga and N Vacancies

The electronic band structures of wurtzite GaN with Ga and N vacancy defects are investigated by means of the first-principles total energy calculations in the neutral charge state. Our results show that the band structures can be significantly modified by the Ga and N vacancies in the GaN samples. Generally, the width of the valence band is reduced and the band gap is enlarged. The defect-induced bands can be introduced in the band gap of GMV due to the Ga and N vacancies. Moreover, the GaN with high density of N vacancies becomes an indirect gap semiconductor. Three defect bands due to Ga vacancy defects are created within the band gap and near the top of the valence band. In contrast, the N vacancies introduce four defect bands within the band gap. One is in the vicinity of the top of the valence band, and the others are near the bottom of the conduction band. The physical origin of the defect bands and modification of the band structures due to the Ga and N vacancies are analysed in depth.