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991.
本实验合成了一种以聚乙烯基酯树脂为原料的聚合物整体柱。在聚合反应中,聚乙烯基酯树脂在聚合中既作为单体同时也作为交联剂,偶氮二异丁腈作为引发剂,十六醇为致孔剂。聚合物制得后以扫描电镜考察了该聚合物的内部形态。同时联合高效液相色谱分别考察了该整体柱的分离能力和载样量。在分离实验中,考察了流动相的浓度及pH值对分离效果的影响。结果表明,溶菌酶可成功的从鸡卵清中分离出,并在较短的时间内取得了较好的分离效果。 相似文献
992.
Catalytic direct dehydrogenation of methanol to formaldehyde was carried out over Ag‐SiO2‐MgO‐Al2O3 catalysts prepared by sol‐gel method. The optimal preparation mass fractions were determined as 8.3% MgO, 16.5% Al2O3 and 20% silver loading. Using this optimum catalyst, excellent activity and selectivity were obtained. The conversion of methanol and the selectivity to formaldehyde both reached 100%, which were much higher than other previously reported silver supported catalysts. Based on combined characterizations, such as X‐ray diffraction (XRD), scanning electronic microscopy (SEM), diffuse reflectance ultraviolet‐visible spectroscopy (UV‐Vis, DRS), nitrogen adsorption at low temperature, temperature programmed desorption of ammonia (NH3‐TPD), desorption of CO2 (CO2‐TPD), etc., the correlation of the catalytic performance to the structural properties of the Ag‐SiO2‐ MgO‐Al2O3 catalyst was discussed in detail. This perfect catalytic performance in the direct dehydrogenation of methanol to formaldehyde without any side‐products is attributed to its unique flower‐like structure with a surface area less than 1 m2/g, and the strong interactions between neutralized support and the nano‐sized Ag particles as active centers. 相似文献
993.
994.
蜂蜜中链霉素与双氢链霉素残留量的液相色谱串联质谱法测定 总被引:3,自引:1,他引:2
建立了液相色谱串联质谱(HPLC-MS/MS)同时对蜂蜜中链霉素和双氢链霉素残留量进行分析的方法。采用磷酸溶液提取,苯磺酸固相萃取柱和C18固相萃取柱串联净化,液相色谱串联质谱测定。链霉素的检出限为0.002 mg/kg,线性范围为0.005~0.100 mg/kg,相关系数为0.9992;双氢链霉素检出限为0.001mg/kg,线性范围为0.002~0.050 mg/kg,相关系数为0.9924。方法回收率为78%~95%,相对标准偏差为2.6%~4.9%。该法实用、准确、快捷,可应用于蜂蜜样品中链霉素和双氢链霉素的同时检测。 相似文献
995.
溴化(a-噻吩甲酰基)甲基三苯鉮1与3-取代苯甲叉基-2,4-戊二酮 2以碳酸钾为碱,在苯中55℃条件下反应,可以较好的收率、高立体选择性地生成反-2-(a-噻吩甲酰基)-3-取代苯基-4-乙氧羰基-5-甲基-2,3-二氢呋喃3。产物结构均经波谱予以确定。本文还提出了生成产物的可能机理。 相似文献
996.
Electrochemical and Photoelectrochemical Study of Self‐assembled Monolayer of Phytic Acid on Brass 总被引:1,自引:0,他引:1
XU Qun-Jie WAN Zong-Yue ZHOU Guo-Ding YIN Ren-He CAO Wei-Min LIN Chang-Jian 《中国化学》2008,26(9):1579-1584
Phytic acid is an environment-friendly reagent for processing metals. The anticorrosion and inhibiting mechanism for phytic acid monolayers self-assembled on a brass (HSn70-1) electrode has been investigated by using electrochemical and photocurrent response methods. The electrochemical measurements indicate that phytic acid is liable to form surface complexes on the brass electrode, and the self-assembled monolayers (SAM) change the structure of the electric double-layer and shift the potential of zero charge positively. The photochemical measurement indicates that the brass electrode shows a p-type photoresponse owing to the formation of a Cu2O layer on its surface, and the presence of SAM weakens significantly the photoresponse, suggesting an excellent effect on anticorrosion, which is consistent with the EIS and polarization curve measurements. Adsorption of phytic acid was found to be typical of chemisorption, which can be reasonably described on the basis of the Langmuir isotherm. 相似文献
997.
998.
ZHAO Chu-feng TANG Ming-sheng WANG Hong-ming WEI Dong-hui ZHAO Jing ZHANG Shou-ren CAO Shu-xia 《高等学校化学研究》2008,24(6):790-792
The reaction mechanisms of intermolecular cleavage reaction of N-(2-hydroxyphenyl)-phthalamic acid were studied via the density functional theory(DFT). All geometries of the reactant, transition states, and products were optimized at the B3LYP/6-31G(d, p) level. Vibration analysis was carried out to confirm its identity as transitions' structure, and the intrinsic reaction coordinate method(IRC) was used to search the minimum energy path. Two possible reaction channels are reported in this article. The calculated results indicate that O-cyclization reaction channel has the lower activation barrier, and therefore, it occurs more easier than the other. 相似文献
999.
为建立简便、灵敏的三试剂自动化分析法测定血清总铁结合力(TIBC),在表面活性剂存在下,用2-(5-硝基-2-吡啶偶氮)-5-[N-正丙基-N-(3-磺酸丙基)氨基]苯酚二钠(Nitro—PAPS)为显色剂测定了血清TIBC。结果表明,该法线性范围0~195μmol/L,平均回收率为100.7%,批内变异系数(CV)和批间变异系数分别为0.019、0.032;与临床检验操作规程推荐的方法比较具有良好的相关性,线性回归方程和相关系数分别为Y=1.0021x+1.2100,r=0.9798;78例健康男性血清TIBC含量(x±2s)为46.8—76.1μmol/L,75例健康女性为52.8—77.6μmol/L。方法简便、灵敏可靠,适合临床应用。 相似文献
1000.