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161.
Xue-Ming Liu 《Tetrahedron letters》2004,45(7):1507-1510
The synthesis, optical, and electrochemical properties of semi-conducting co-oligomers of biphenyl/oligothiophenes and homo-oligophenylenes derived from a precursor 4-bromo-4′-(n-butyl)-2,2′-biphenyl, which was synthesized by a direct alkylation from 4,4′-dibromo-2,2′-biphenyl using n-butyl lithium, are reported. 相似文献
162.
Mechanical properties decay and morphological behaviour of biodegradable films for agricultural mulching in real scale experiment 总被引:1,自引:0,他引:1
Giacomo Scarascia-Mugnozza Giuliano Vox Barbara Immirzi 《Polymer Degradation and Stability》2006,91(11):2801-2808
The use of plastic materials in agriculture causes the serious drawback of huge quantities of waste. The introduction of biodegradable materials, which can be disposed directly into the soil, can be one possible solution to this problem. Biodegradable materials are actually innovative materials; therefore, their physical properties must be evaluated in relation to their functionality during the use in field. In the present research results of experimental tests carried out on biodegradable films used in strawberries protected cultivation are presented. The decay of some relevant physical parameters of biodegradable films during the cultivation period was monitored by laboratory tests (SEM analysis, mechanical tensile tests and infrared reflectance spectroscopy). Infrared spectroscopy clearly indicated that the mechanical degradation starts from the starch component of the material. Tensile tests showed that the value of elongation at break of biodegradable materials decreased in some cases by 300% after 10 days of field application. 相似文献
163.
提出了用草酸.邻菲哕啉去除硅灰石中Fe^2 的方法,研究了浸取剂的浓度、浸取时间和温度等条件对Fe^2 的去除率的影响,在最佳的浸取条件下,Fe^2 的去除率达到98.35%。在去除猝灭剂后的硅灰石矿物中,掺加适量的稀土激活剂Eu^3 ,通过高温固相法制成荧光发光材料,发光强度明显提高,接近于化学试剂合成的发光材料。 相似文献
164.
165.
A batch of sulphydryl cotton microcolumns was prepared and charged with a mixed Hg standard solution (methyl-, ethyl- and inorganic Hg, 10 g l–1 as Hg, 3 ml) and stored at 4 °C in a light-tight box. At regular time intervals over a 4 month period microcolumns were removed and Hg species were quantified by gas chromatography microwave-induced plasma atomic emission spectrometry (after elution, extraction and derivatization steps). It was found that analyte recoveries for methyl- and inorganic Hg were quantitative over the 4 month period while ethyl-Hg species appeared to be stable for up to 2 months. 相似文献
166.
C. Osterroht 《Chromatographia》1987,23(6):419-422
Summary A method for the determination of fatty acids of the molecular weight range of propionic to erucic acid is reported. The acids are converted to either p-bromophenacyl-or p-phenylphenacylesters and the esters are separated by HPLC and detected by UV-absorption. Twentytwo esters, including saturated, monoolefinic and polyunsaturated ones were separated within one HPLC-run. The detection limit is about 5 pmol per fatty acid. The application of the method to particulate material is described. 相似文献
167.
168.
169.
Bernd GüNTHER 《中国科学B辑(英文版)》2007,50(6)
The interaction between stabilizers and nanoparticles is one of the important factors to prepare stable magnetic fluids. The magnetic nano-size Fe3O4 core with single domain and the average grain size around 8-12 nm were prepared by chemical precipitation method. The O/Fe molar ratio of the particle surface was measured by X-ray photoelectron spectroscopy (XPS). The heat effects of stabilizers ad- sorption on nanoparticles were measured by solution calorimetry. The excess amount of oxygen was possibly the result of the hydroxygen formed on the surface of the nanoparticles. The heat effects showed that compounds containing carboxyl groups can be adsorbed chemically on magnetite by forming chemical bonds. The other stabilizers involving NH-groups, such as polyethylene-imine, can be adsorbed physically. The exothermic value is about half of the former case. 相似文献
170.