排序方式： 共有93条查询结果，搜索用时 343 毫秒
41.
本文采用顶空气相色谱法测定化妆品中甲醇的含量。用氢火焰离子化检测器检测，化妆品中甲醇的最低检测浓度为1．5mg／kg，在样品中加标量分别为20mg和40mg时，回收率为91．9％-95．2％，依本法取两份样品分别测6次，变异系数为1．6％-2．8％。 相似文献
42.
Analysis of ATPase characterized type I and type II fibres from biopsy samples of the vastus lateralis muscle of four male subjects showed a selective distribution of carnosine and free taurine similar to that observed in other species. The mean carnosine concentration was twice as high in type II compared with type I muscle fibres (23.2 +/- 17.8 and 10.5 +/- 7.6 mmol . kg -1 dry weight, respectively), while taurine was four times higher in type I compared with type II muscle fibres (39.2 +/- 17.8 and 9.6 +/- 2.6 mmol . kg -1 dw, respectively). Overlap in the concentration of carnosine or taurine between fibre types occurred only once in one subject. There was no overlap between fibre types in the ratio of carnosine to taurine. Higher carnosine concentrations in type II fibres will result in a greater contribution to the buffering of H+ arising from anaerobic metabolism. The contribution in a type II fibre with the highest carnosine content was estimated to equal 28% of that from other sources. 相似文献
43.
Shu-dong Jiang Zhi-hua Wang Jun-hu Zhou Zheng-cheng Wen Ke-fa Cen 《浙江大学学报(A卷英文版)》2009,10(9):1327-1333
Reaction mechanisms of SO2 with O3 and H2O2 were investigated using quantum chemistry ab initio methods. Structures of all reactants, products, and transition states were optimized at the B3LYP/6-311G＋（3df,2p） level, and energy calculations were made at the G2M level. SO2 reactions with O3 and H2O2 occurred by O-abstraction and OH-abstraction by SO2, respectively, at length forming SO3＋O2 （3Eg） and H2SO4. For SO2＋O3 reactions the barrier height was predicted to be 9.68 kcal/mol with a rate constant of 3.61 × 10^-23 cm^3/（molecule.s） at 300 K, which is below the experimental upper limit. The rate constant predicted for this reaction accords well with the one provided by National Institute for Standards and Technology （NIST） in 250-500 K. For SO2＋H2O2 reactions the barrier height was predicted to be 62.39 kcal/mol with a rate constant of 2.48× 10^-61 cm^3/（molecule.s） at 300 K. 相似文献
44.
The hydrothermal experiments with ketones and formic acid showed that the hydrogen transfer reduction of ketones can be conducted using formic acid as a hydride donor in the presence of NaOH at 300 ℃. The yield of alcohols was considerably higher at a much lower ratio of hydrogen source to ketones than the traditional Meerwein-Ponndorf-Verley （MPV） reduction, reaching 60% for isopropanol from acetone and 70% for lactic acid from pyruvic acid. Water molecules may act as a catalyst in the hydrogen transfer reduction of ketones under hydrothermal conditions. 相似文献
45.
合成了氢键连接的二维超分子配位化合物[Cu（mal）（tpm）（H2O）]·2H2O（mal=丙二酸,tpm=三吡唑甲烷）,并用元素分析和电子顺磁共振谱进行了表征。X射线单晶衍射表明该化合物的晶体属单斜晶系,Cc空间群,晶胞参数a=1．3624（2）nm,b=0．79318（14）nm,c=1．7526（3）nm,α=90°,β=102．352（3）°,γ=90°,V=1．8501（6）cm^3,Z=4。中心Cu（Ⅱ）离子为五配位,处于扭曲的四方锥配位环境中。晶格水与配位水形成较强的氢键将配合物连接成二维超分子结构。 相似文献
46.
密闭式种猪舍部分有害气体分布状况观测 总被引：3，自引：0，他引：3
本研究对一栋密闭式种猪舍部分有害气体的分布状况进行了观测,结果表明,在舍内0.2m、0.5m和0.8m的不同高度层中,氨气的平均浓度分别为6.7mg/kg、8.9mg/kg和4.7mg/kg,其中,0.5m高度层氨气浓度显著高于0.8m高度层的(P＜0.05),日高峰值出现在6:00时的0.5m高度层,为17.6mg/kg;硫化氢的平均浓度分别为0.16mg/kg、0.15mg/kg和0.13mg/kg,各浓度间差异不显著性(P＞0.05),日高峰值出现在14:00时的0.2m高度层,为0.25mg/kg.整个试验期间氨气和硫化氢最高浓度和日平均浓度均低于畜禽环境空气质量标准. 相似文献
47.
采用溶液结晶法制备了草酸钾-过氧化氢（K2C2O4·H2O2）晶体,过氧化氢的含量接近于理论值．利用红外光谱和X-射线衍射对草酸钾-过氧化氢加合物的结构进行了表征,得到了其红外光谱和X-射线衍射谱图,并对谱图进行了简要分析． 相似文献
48.
惠萍 《广东教育学院学报》2008,28(5):52-54
用B-splines技术将波函数在径向和角向同时展开,考虑两核之间的相互作用,计算超强外磁场中,氢分子离子基态（m=0）和低激发态（m=-1,-2,-3,-4）的能级与两核间距离的关系,计算结果在2．35×10^6→2．35×10^8T整个区域比绝热近似结果的精度提高0．01到0．02． 相似文献
49.
Sedum alfredii Hance has been identified as zinc (Zn) and cadmium (Cd) co-hyperaccumulator. In this paper the relationships of Zn or Cd hyperaccumulation to the generation and the role of H2O2 in Sedum alfredii H. were examined, The results show that Zn and Cd contents in the shoots of Sedum alfredii H. treated with 1000 μmol/L Zn2 and/or 200 μmol/L Cd2 increased linearly within 15 d. Contents of total S, glutathione (GSH) and H2O2 in shoots also increased within 15 d, and then decreased. Total S and GSH contents in shoots were higher under Cd2 treatment than under Zn2 treatment. However, reverse trends of H2O2 content in shoots were obtained, in which much higher H2O2 content was observed in Zn2 -treated shoots than in Cd2 -treated shoots. Similarly, the microscopic imaging of H2O2 accumulation in leaves using H2O2 probe technique showed that much higher H2O2 accumulation was observed in the Zn2 -treated leaf than in the Cd2 -treated one. These results suggest that there are different responses in the generation of H2O2 upon exposure to Zn2 and Cd2 for the hyperaccumulator Sedum alfredii H. And this is the first report that the generation of H2O2 may play an important role in Zn hyperaccumulation in the leaves. Oar results also imply that GSH may play an important role in the detoxification of dissociated Zn/Cd and the generation of H2O2. 相似文献
50.
JIANG Zhao-bo LAO Zhen-hua 《江西蓝天学院学报》2008,(1)
研究气、液、固三相体系中烯烃氢甲酰化反应固载催化剂的制备方法及影响因素。重点论述固载铑催化剂的制备,包括对不同催化剂载体的优选及不同催化剂制备条件的研究。用不同方法进行催化剂制备并考察其催化反应的性能,最终确定了合适的固载铑催化剂的制备方法。 相似文献