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51.
The boxes contained kiwifruits were irradiated with cobalt-60 γ-rays at different dosages (0.6 , 1.8 and 3.6 KGy) and stored in a room ventilated at night, the natural ambient air being used as cool source.The results showed that the treatment which fruits irradiated with 0.6 KGy was the best after 85 days. It gave the normal-fruit rate of 95.10%, fruit flesh hardness of 4.10 Kg · cm-2, fresh and plump fruits, good quality and less Vc loss. 相似文献
52.
Ni-B和Ni-Ce-B超细非晶态合金的退火晶化及其催化性能 总被引:2,自引:0,他引:2
采用XAFS,XRD和DTA方法研究了Ni-B和Ni-Ce-B超细非晶态合金在退火过程中的结构变化及其结构与催化性能的关系.活性结果表明,在退火温度为623K时,Ni-B和Ni-Ce-B样品的苯加氢催化反应转化率最高,分别为63%和81%,0.3%Ce的掺入提高了Ni-Ce-B的催化活性.DTA结果表明,Ni-B超细非晶态合金在598和653K有两个晶化峰,而Ni-Ce-B样品有548,603,696和801K四个晶化峰.XAFS和XRD结果进一步说明,在573K退火时,Ni-B样品晶化生成晶态Ni3B和纳米晶Ni,此时Ni-Ce-B仅有少量晶态Ni3B生成.在673K退火时,Ni-B样品中的Ni3B开始分解生成晶态Ni,同时纳米晶Ni聚集并形成大颗粒晶态Ni,而Ni-Ce-B样品晶化生成晶态Ni3B和纳米晶Ni.在773K和更高的温度退火处理后,Ni-B样品中Ni的局域环境结构与金属Ni箔基本一致,但Ni-Ce-B样品晶化生成的Ni晶格有较大畸变,同时Ni3B并未分解.说明0.3%的Ce对提高Ni-Ce-B样品的稳定性有显著作用.本文首次报道了Ni-B和Ni-Ce-B超细非晶态合金中苯加氢催化活性中心为纳米晶Ni和类似于金属Ni的Ni-B非晶态合金. 相似文献
53.
54.
本文扼要地介绍了固体激光质谱学问世20多年来的发展和现状。其中包括有:固体激光质谱的简介和特色;发展过程中有重要贡献科学工作者的主要成就;它的有关基本理论;从仪器和分析实践两个方面介绍其发展概况。文中还就上述几个方面列出带综论性文献,以便读者作进一步了解。最后作者还展望了今后固体激光质谱学的发展前景。 相似文献
55.
The performance of a recently developed method to generate representative atomistic models of amorphous polymers has been investigated. This method, which is denoted SuSi, can be defined as a random generator of energy minima. The effects produced by different parameters used to define the size of the system and the characteristics of the generation algorithm have been examined. Calculations have been performed on poly(L,D-lactic) acid (rho = 1.25 g/cm3) and nylon 6 (rho = 1.084 g/cm(3)), which are important commercial polymers. 相似文献
56.
采用差示扫描量热法(DSC)、X射线衍射(XRD)和透射电镜(TEM)研究了Y对Nd-Fe-Al-Ni非晶合金热稳定性和晶化行为的影响。结果表明,淬火态的Nd60Fe20Al10Ni10-xYx(x=0,2)合金基本为非晶组织同时还含有少量的淬态相,Y的加入抑制了淬态相的析出。加入Y后,非晶合金的晶化开始温度和晶化峰值温度都向高温方向移动,证明其热稳定性提高。Y的加入改变了合金的晶化方式和最终晶化产物,使非晶基体中析出的晶化相更加弥散圆整细小。并且Y具有在化学上钝化氧杂质的作用,从而抑制了氧的有害作用。利用Kissinger方程获得了Nd60Fe20Al10Ni8Y2非晶合金的晶化开始和晶化峰值激活能分别为1.21和1.16 eV。 相似文献
57.
Three novel perylene polyimides (PPIs) containing p‐n diblock units were designed and synthesized for use in dye‐sensitized mesoporous TiO2 solar cells. They all dissolve in m‐cresol and N‐methyl‐2‐pyrrolidone (NMP). Their visible light absorption, electrochemical and photoelectrochemical properties were systematically studied. The polyimides have band gap energies of 2.16, 2.19 and 2.25 eV deduced from ultraviolet–visible absorption spectra, and electron affinity (Ea) and ionization potential (IP) of ?3.93 and 6.10 eV for PPI1, ?3.94 and 6.13 eV for PPI2, ?3.93 and 6.59 eV for PPI3, respectively, deduced from cyclic voltammogram. Experimental data show that introduction of 4,4′‐bisaminetriphenylamine cannot only greatly enhance optic‐electro conversion efficiency, but also enhance the dissolubility which in favorable for making the devices. The relationship of structure and properties of PPI is discussed and the mechanism of photocurrent generation is explained. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
58.
Maria?Victoria Roux Paul?J.?Smith Joel?F.?LiebmanEmail author 《Structural chemistry》2005,16(1):73-75
Despite their seeming simplicity, substituted guanidines have not particularly caught the attention of the thermochemical community. The current paper compares the enthalpy of formation of solid substituted guanidines with correspondingly substituted benzenes, also as solids. 相似文献
59.
Agustín Urretabizkaia Gurutze Arzamendi María J. Unzu Jos M. Asua 《Journal of polymer science. Part A, Polymer chemistry》1994,32(9):1779-1788
A method for the calculation of the optimal monomer addition policies for polymer composition control in emulsion terpolymerization is developed. The method is applied to reactors with and without limited heat removal capacity. A mathematical model that incorporates the main features of the vinyl acetate/methyl methacrylate/butyl acrylate high solids content emulsion terpolymerization system allows the calculation of the composition of the initial charge of the reactor and the time-dependent monomer addition rates required. © 1994 John Wiley & Sons, Inc. 相似文献
60.
Anna Kowalska Zygmunt Kowalski Andrzej Kotarba Andrzej Barański 《Mikrochimica acta》1990,100(5-6):349-353
The analytical procedure of determination of Fe(II) in the presence of Fe(III) in milligram samples is proposed. A solid sample is dissolved in hydrochloric acid in argon atmosphere. Subsequently, the pH-value of the solution is fixed and Fe(III) complexed by phosphoric buffer. At the next step Fe(II) is oxidized by -molybdosilicic acid. Finally, the intensity of colouring caused by the reduced form of the acid is measured at the wavelength 770 nm. The proper treatment of the sample during oxidation, and immediately before, is decisive for the accuracy of the analysis. The method was verified by means of the analysis of synthetic magnetite. The theoretical content of Fe(II) was 24.12%, the determined one was 24.02 ± 0.10%. The method was applied to the determination of the homogeneity of an iron catalyst for ammonia synthesis. 相似文献