肉食品中常见4种抗生素残留的高效液相色谱分析

建立了同时测定肉食品中泰乐菌素、替米考星、氯霉素、氟苯尼考的高效液相色谱方法,样品经乙腈提取,正己烷脱脂, HLB小柱净化后,以C18反相色谱柱为分离柱,甲醇－磷酸二氢钠缓冲溶液(pH 3.0,含体积比为10％的甲醇溶液）为流动相进行梯度洗脱,检测波长λ为275 nm.泰乐菌素、替米考星、氯霉素、氟苯尼考的线性范围是0.1～20.0 mg/L,相关系数分别为0.9987、0.9992、0.9985、0.9970.其平均回收率为75％～87%,相对标准偏差为1.35％～5.41％,泰乐菌素、替米考星、氯霉素、氟苯尼考的检出限分别为20、32、19、16μg/kg.方法满足肉食品中泰乐菌素、替米考星、氯霉素、氟苯尼考的残留量测定.     

城市垃圾与煤在CFBC试验台上的混烧试验

城市垃圾的焚烧处理一直是人们关注的研究领域。本文详细报告了一种城市垃圾与劣质煤在0.15兆瓦CFBC试验台上的混烧试验。试验结果表明,城市垃圾与劣质煤在循环流化床中的混烧可以很好地满足稳定和高温燃烧的要求,通过添加石灰石等含钙物料可以有效地在燃烧过程巾控制SO2、HCl和二(?)英类污染物的生成。     

强脉冲电磁场对金属凝固组织影响的研究

提出了用强脉冲磁场和电流细化金属凝固组织的新工艺.与未经磁场或电流处理的凝固样品相比,强脉冲电磁场能够显著地改善LY12铝合金的凝固组织,使晶粒明显细化、球化;电磁场的强度愈强,这种改善效果愈明显.对该新工艺的细化机理进行了理论分析,同时,指出了实验中的新现象和新问题. 关键词：     

Stereochemistry of reactions of the inhibitor/substrates L- and D-beta-chloroalanine with beta-mercaptoethanol catalysed by L-aspartate aminotransferase and D-amino acid aminotransferase respectively

Two members of the alpha-family of PLP-dependent enzymes, L-aspartate aminotransferase and D-amino acid aminotransferase, have been shown to catalyse beta-substitution of L- and D-beta-chloroalanine respectively with beta-mercaptoethanol, reactions typical of the beta-family of PLP-dependent enzymes. The reaction catalysed by L-aspartate aminotransferase has been shown to occur with retention of stereochemistry, a typical outcome for reactions catalysed by beta-family enzymes. There are also indications that the reaction catalysed by D-amino acid aminotransferase may involve retention of stereochemistry. Both enzymes have been shown to catalyse exchange at C-3 when the appropriate enantiomer of beta-chloroalanine is the substrate.     

A New ent-Kaurane Diterpenoid from Isodon enanderianus

Isodon enanderianus (Hand. -Mazz.) H. W. Li, has been used in folk medicine as anti-inflammatory and detoxified agent1. The Isodon genus is known to be rich in ent-kaurane diterpenoids, a series of new ent-kaurane diterpenoids have been isolated from the dried leaves of I. enanderianus2-4. In order to find more biologically active substances, we have carefully investigated the chemical constituents of I. enanderianus collected in Shiping county of Yunnan province, and as a result, enanderi…     

Direct photon production from pions and protons at 200 GeV/c

Direct photon production has been studied by an experiment performed with the NA3 spectrometer at CERN, using incident negative and positive beams at 200 GeV/c interacting with an isoscalar Carbon target. Two different triggers have been used; one of them requires the photon conversion. The experiment is sensitive to direct photons produced with 3.0≦P _T ≦6 GeV/c and center-of-mass rapidity ?0.4≦y ^*≦1.2. Inclusive cross sections are given for incident π^± and protons, and compared with second order QCD predictions; finally an estimation of the gluon structure function of the nucleon is given.     

高寒地区浅基础埋深问题

运用工程实例论述了影响高寒地区浅基础埋深的重要因素, 提出了基础埋深的具体计算方法。     

HPLC-MS-MS法测定水体中残留的氨基甲酸酯类农药

应用高效液相色谱-串联质谱(HPLC-MS-MS)联用技术,建立了检测水体中氨基甲酸酯类农药残留的方法。水样经氨基柱固相萃取,二氯甲烷洗脱,梯度流动相洗脱,电喷雾正离子(ESI+)模式采集、选择反应性监测模式(SRM)对定性、定量离子进行MS/MS测定。5种氨基甲酸酯类农药在5～200ng/L范围内线性关系良好,回收率为80%～92%,相对标准偏差均小于10%,方法检出限分别为:异丙威和仲丁威为1.4ng/L,克百威和甲萘威为1.5ng/L,恶虫威为1.6ng/L。该方法适用于水体中氨基甲酸酯类农药残留的检测。     

Partial Lagrangian relaxation for general quadratic programming

We give a complete characterization of constant quadratic functions over an affine variety. This result is used to convexify the objective function of a general quadratic programming problem (Pb) which contains linear equality constraints. Thanks to this convexification, we show that one can express as a semidefinite program the dual of the partial Lagrangian relaxation of (Pb) where the linear constraints are not relaxed. We apply these results by comparing two semidefinite relaxations made from two sets of null quadratic functions over an affine variety.