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31.
火花激发原子发射光谱法应用于直径小于8mm的不锈钢线材的分析,对此类试样应用了一种特制的夹具,用块状标准样品制作工作曲线。由于线状试样和块状标准样品之间的形状差异所产生的系统不确定度借采用同类型标样作校正,对共存元素的相互干扰也采用了相应的校正方法。其它分析条件,包括严格的制样工序,氩气的纯度要求及其流量控制,以及光源的最佳条件等,作了深入的试验。按所提出的方法测定了不锈钢线材试样中碳、硅、锰、磷、硫、铬、镍及钛等8个元素。经校正后的结果与化学法测得结果相符。 相似文献
32.
AlkylationofBenzenewithPropeneoverHβZeolite──TheEffectofReactionConditionsontheDistributionofProductsMAJun,SHENJian-ping,SUNT... 相似文献
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Conjugate additions of amino alcohols derived from alpha-amino acids to vinyl sulfones, followed by N-benzylation, chlorination, and intramolecular alkylation, provide a convenient route to substituted pyrrolidines. The process is accompanied by the stereospecific rearrangement of substituents from the alpha-position of the amine to the beta-position of the product and takes place via the corresponding aziridinium ion intermediates. Another type of rearrangement was observed during the reaction of (2-piperidine)methanol or 2-(2-piperidine)ethanol with phenyl trans-1-propenyl sulfone, in which the methyl group appears to migrate from the beta- to the alpha-position of the sulfone moiety. This process involves the isomerization of phenyl trans-1-propenyl sulfone to phenyl 2-propenyl sulfone by the addition-elimination of catalytic benzenesulfinate anion to the former vinyl sulfone, followed by conjugate addition of the amino group to the latter sulfone. Chlorination and intramolecular alkylation then afford the corresponding rearranged indolizidine and quinolizidine derivatives, respectively. 相似文献
35.
研究了Ni/Fe催化剂对废水中偏二甲肼臭氧化分解的催化作用,考察了组分含量、体系的pH值和偏二甲肼初始浓度对催化反应的影响.结果表明,Ni/Fe催化剂对水中偏二甲肼的臭氧化具有良好的催化活性.催化剂组分含量、体系的pH值和初始浓度对反应的影响程度不大.对催化剂的XRD表征结果表明,催化剂主要由尖晶石结构的铁酸盐和FeNi3合金相组成,催化剂的良好催化性能与催化剂中尖晶石结构的铁酸盐和FeNi3合金相的形成有关. 相似文献
36.
Pt(PPh_3)_2Cl_2在碱性介质中,与一氧化碳直接进行还原及羰基化反应,得到五种膦取代的羰基铂配合物:Pt_5(μ_2-CO)_5(CO)(PPh_3)_4 1,Pt_3(μ_2-CO)_3(PPh_3)_3 2,Pt_3(μ_2-CO)_3(PPh_3)_4 3,Pt_4(μ_2-CO)_5(PPh_3)_4 4,以及Pt(Cl)(PPh_3)_2(COOCH_3) 5。经X-射线单晶衍射分析,确定了新的三核铂羰基簇2以及配合物5的分子结构。还讨论了1和5的生成机理。 相似文献
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Mesoporous molecular sieves were synthesized from Beta and Fau zeolite precursors through S+X−I+ route under extremely acidic conditions in parallel (designated as MBeta and MFau, respectively). The textural properties of MFau were different from its MBeta counterpart but resembled normal MCM-41 silica from TEOS. Al content in MBeta was almost equivalent to that in the initial Beta zeolite precursors, whereas only trace Al species was present in MFau from elemental analysis results. The hydrothermal stability of MBeta after post-synthesis ammonia treatment was considerably improved compared with normal MCM-41 aluminosilicates, whereas the MFau after the same procedure was as unstable as normal MCM-41 silica. Thus, the assembly behaviors of Beta and Fau zeolite precursors were comparatively studied based on these results. The microstructure of Fau zeolite precursors were degraded by the extremely acidic condition, and Al species was dissolved into the synthesis mixture. However, Beta zeolite precursors survived the chemical attack of extremely acidic media and were incorporated into mesostructured framework as primary building units. 相似文献
39.
密胺树脂/硼酸锌双层包覆微胶囊化红磷的制备及其在阻燃聚烯烃中的应用 总被引:3,自引:0,他引:3
描述了采用密胺树脂和硼酸锌连续双层包覆微胶囊化红磷(MRP)的最新制备方法。采用红外光谱、电子能谱和透射电镜等分析手段对其进行了表征,并证实红磷已被完全包覆。实验数据表明:经包覆的MRP的热稳定性获得了明显改善,吸水率和磷化氢的发生量均大大减少。MRP作为阻燃助剂应用于聚烯烃阻燃材料表现出了良好的阻燃效果。实时红外和热失重测量以及扫描电镜观察表明:其阻燃机制是红磷受热时与树脂反应促进了含磷膨胀炭层的形成,从而提高了材料的热稳定性,碳层起到了隔氧、隔热作用,而且主要在凝聚相中发挥其阻燃作用。 相似文献
40.
Yunhui Zhai Xijun Chang Yuemei Cui Ning Lian Shoujun Lai Hong Zhen Qun He 《Mikrochimica acta》2006,154(3-4):253-259
A rapid, selective method that utilize 4-(2-Pyridylazo)-resorcinol (PAR)-modified nanometer SiO2 (nanometer SiO2–PAR) as a new solid-phase extractant for preconcentration of trace mercury (II) has been developed. The adsorption property
of nanometer SiO2–PAR for metal ions was studied by selectively extracting different metal ions from aqueous solutions. The results revealed
an excellent affinity of the nanometer SiO2–PAR for mercury (II) in presence of interfering metal ions at pH 4. The main parameters of solid-phase extraction such as
shaking time, elution and sample dilution effect were studied. The extractant shows rapid kinetic sorption, and the adsorption
equilibrium of mercury (II) on nanometer SiO2–PAR was achieved in less than 2 min. The adsorbed mercury (II) was easily eluted by 4 mL of 6 mol L−1 HCl. The maximum preconcentration factor was 50. The maximum static adsorption capacity was 276 μmol g−1 at pH 4. The detection limit (3σ) was 0.43 μg L−1 for cold vapor atomic absorption spectrometry (CVAAS), and the relative standard deviation of the eight replicate determinations
was 2.4% for the determination of 2.0 μg of Hg(II) in 100 mL water sample. The method was applied to the determination of
trace mercury (II) in sample solutions with satisfactory results. 相似文献