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61.
D.G. Schmidling 《Journal of Molecular Structure》1975,25(2):313-317
MINDO/2 semi-empirical molecular orbital theory can be used to calculate mean-square amplitudes of vibration and shrinkage effects. Calculated values for ethylene and benzene deviate from spectroscopic values by an average of 4 %. The force field calculations can be carried out conveniently in Cartesian coordinates. 相似文献
62.
伴随着市场经济模式的根本改变,商业传播的方式、策略等也发生着质的变化。当然,最具冲击力的,应该是它对社会的消费文化、消费理念以及企业的经营理念、服务理念等社会层面和文化层面上的巨大影响。因此,如何通过不同类型的品牌代言人提升品牌资产成为了学术界和企业界关注的一个焦点。为此,通过对"90后"在校大学生进行调查,针对实证研究结论,最终提出适应"90后"在校大学生群体的品牌代言传播策略建议。 相似文献
63.
Hongbo Wei Hongli Zhang Shoule Han Shan Mu Ke Huang Guzhou Chen Weiqing Xie 《Tetrahedron letters》2019,60(35):150973
Asymmetric synthesis of the marine nor-sesquiterpenoid (+)-austrodoric acid and (+)-austrodoral in seven and nine steps respectively from Wieland-Miescher ketone was described herein. The synthesis featured an oxidative ring contraction of α-formyl cyclic ketone mediated by H2O2 to forge the hydrindane scaffold together with the contiguous quaternary carbon centers simultaneously. 相似文献
64.
Reductive immobilization of radioactive pertechnetate (99TcO4?) in simulated groundwater was studied by prepared carboxymethyl cellulose (CMC) and starch stabilized zero valent iron nanoparticles (nZVI), and long-term remobilization of reduced Tc was also evaluated under anoxic and oxic conditions. The stabilized nZVI can effectively reduce soluble 99Tc(VII) to insoluble 99Tc(IV), and they can be easily delivered into a contaminated groundwater zone and facilitate in situ remediation. In this study, CMC-stabilized nZVI showed higher reactivity than that using starch as the stabilizer. Batch experiments indicated that more than 99% of 99Tc(VII) (C0 = 12 mg/mL) was reduced and removed from groundwater by CMC-stabilized nZVI with a CMC content of 0.2% (w/w) at a broad pH of 5–8. X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analyses further confirmed that 99Tc(VII)O4? transformed into 99Tc(IV)O2 (s). The presence of bicarbonate exhibited insignificant effect on Tc immobilization, while humic acid (HA) inhibited reaction mainly due to retardation on electron transfer and formation of Tc(IV)-HA complexes. More interesting, the immobilized Tc(IV) remained insoluble even after 120 d under anoxic condition, while only ~21% was remobilized when exposed to air. Therefore, bio-macromolecules stabilized nZVI nanoparticles could be a viable alternative for in situ remediation of radioactive contamination in groundwater. 相似文献
65.
Badr M. Thamer Hany El-Hamshary Salem S. Al-Deyab Mohamed H. El-Newehy 《Arabian Journal of Chemistry》2019,12(6):747-759
Electrospun carbon nanofibers (ECNFs) have attracted significant attention in recent years as relatively inexpensive alternative to carbon nanotubes for adsorption organic pollutants. In this study, ECNFs were fabricated from polyacrylonitrile (PAN) using an electrospinning technique, followed by carbonization and oxidation via treatment with a H2SO4/HNO3 mixture. The prepared oxidized electrospun carbon nanofibers (O-ECNFs) were characterized using scanning and transmission electron microscopy (SEM and TEM), Fourier transform infrared (FT-IR), Brunauer-Emmett-Teller (BET), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). The O-ECNFs were used as nano-adsorbents for the adsorption of methylene blue (MB) from aqueous solution. The adsorption of MB by the O-ECNFs was studied as a function of pH, time, adsorbent dosage, MB concentration, and temperature. ECNF functionalization enhanced the adsorption capacity towards MB dye compared pristine ECNFs. Detailed analysis of the adsorption kinetics showed that the adsorption process followed a pseudo-second-order model. The adsorption isotherm was best fit by the Langmuir model. The thermodynamic results showed that MB adsorption onto the O-ECNFs was endothermic and spontaneous. 相似文献
66.
Govinda Lakhotiya Namdeo Belsare Abhimanyu Rana Vinay Gupta 《Current Applied Physics》2019,19(4):394-399
Here, we report Cu2S nanocrystals based non-fullerene ternary polymer solar cells by incorporating Cu2S in conjugated polymer (PBDB-T: poly[(2,6-(4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)-benzo[1,2-b:4,5-b′]dithiophene))-alt-(5,5-(1′,3′-di-2-thienyl-5′,7′-bis(2-ethylhexyl) benzo[1′,2′-c:4′,5′-c′]dithiophene-4,8-dione))]) and small molecule non-fullerene compound (ITIC:3,9-bis(2-methylene-(3-(1,1-dicyanomethylene)-indanone))-5,5,11,11-tetrakis(4-hexylphenyl)-dithieno[2,3-d:2′,3′-d′]-s-indaceno[1,2-b:5,6-b′]dithiophene). The devices were fabricated in inverted configuration i.e. ITO/ZnO/PBDB-T: Cu2S NCs: ITIC/MoO3/Ag. Effect of concentration of Cu2S nanocrystals on the performance parameters of PBDB-T: ITIC based organic solar cells is studied. An enhancement in the power conversion efficiency from 8.24% to 9.53% is achieved for the optimum concentration of Cu2S nanocrystals in the organic photoactive blend. The cause of improvement in the performance parameters of the device is investigated by means of the light intensity dependent electrochemical impedance spectroscopy and atomic force microscopy. It is found that the devices with Cu2S nanocrystals have less trap-assisted recombination. 相似文献
67.
郑彦 《宁波大学学报(理工版)》2011,24(2):124-127
Malmquist指数被广泛运用于经济领域中的效率变化及其原因分析.对厦门城市职业学院"三校合并"后的办学效率分析表明,三校合并后的3年中学院在办学效率方面有了很大的提高,效率改进主要是依靠管理水平的提高和制度的规范,学院在人才培养模式创新和高职教育改革等方面还有许多工作需要深化. 相似文献
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