油葵SSR反应体系的优化

采用改良CTAB法从油葵种仁中提取基因组DNA,用于SSR-PCR反应。对影响油葵SSR-PCR反应的几个重要因子进行了探讨,确定了最佳的反应体系:在总体积为25μL中,DNA为2.0 ng/μL,Mg2+浓度为1.5 mmol/L,dNTPs浓度为0.2 mmol/L,Taq酶量为2.0 U,引物浓度为0.25μmol/L,退火温度为52～54℃,扩增的谱带清晰、多态性丰富。该SSR-PCR反应体系为油葵亲缘关系分析奠定了技术基础。     

离子色谱法同时测定大气降水中的四种阳离子

采用离子色谱法同时分析大气降水中的四种阳离子(Na~+、K~+、Mg~(2+)、Ca~(2+)),结果显示该方法分离效果和线性良好,且方便快捷、灵敏度高、精密度好,满足大气降水中Na~+、K~+、Mg~(2+)、Ca~(2+)的分析要求。     

海水条件下重金属离子对5052铝合金表面改性层腐蚀性影响

在海洋环境下工件表面常涂覆铝锌改性层作为防腐蚀涂层。海洋环境下的重金属离子是影响铝及其合金腐蚀的重要因素之一。文章研究了海水中不同重金属离子(Hg^(2+)和Cu^(2+))含量对5052铝合金表面铝锌改性层的腐蚀性能影响。通过电化学实验发现随着Hg^(2+)含量的增大,铝锌改性层的耐蚀性逐渐减弱。同样随着Cu^(2+)浓度的增大,铝锌改性层的耐蚀性下降。通过浸泡实验,发现随着金属离子(Hg^(2+)、Cu^(2+))的浓度增大,年腐蚀深度逐渐增大。当Hg^(2+)浓度低于5μg/L时年腐蚀深度不超过20μm;当Cu^(2+)浓度低于10μg/L时,年腐蚀深度基本在20μm左右。     

几种重金属离子在甲基橙光催化降解中的作用研究

采用溶胶-凝胶法制备了TiO_2/GR复合材料为光催化剂,以模拟太阳光为光源,研究Cr~(6+)、Fe~(3+)、Cu~(2+)、Ag~+4种重金属离子对甲基橙光催化降解的作用,考察了重金属离子种类、重金属离子浓度、溶液酸度和反应气态氛围对甲基橙光催化效果的影响。实验结果表明:在固定甲基橙和4种重金属离子的的浓度均为30mg/L,除Cr~(6+)对甲基橙的光催化降解起抑制作用外其它3种重金属离子均起促进作用,Fe~(3+)促进效果最好,经过60min光照后,甲基橙的降解率可高达99.6%;当4种重金属离子的浓度下降至5mg/L,对甲基橙光催化降解的促进作用则表现为Cr~(6+)>Fe~(3+)>Cu~(2+)>Ag~+;反应体系的酸度越大,4种重金属离子对甲基橙光催化降解的促进作用越小,在pH=3时,4种重金属离子对甲基橙光催化降解的促进作用最好,表现为Cr~(6+)>Fe~(3+)>Cu~(2+)>Ag~+,而当pH=9时则4种重金属离子均表现为抑制作用;4种重金属离子在O_2、空气和N_2这3种气态氛围中均对甲基橙的光催化降解起促进作用,表现为O_2>空气>N_2。     

高产漆酶菌株Irpex lacteus TY-3的分离鉴定及酶学性质研究

漆酶具有特殊的催化能力,能降解木质素和腐殖质等,在染料降解及脱色、生物漂白与制浆和食品工业等多个领域具有广泛的应用前景。文章从土壤中分离筛选获得高产漆酶的菌株,利用形态学和分子生物学对其进行鉴定,并命名为Irpex lacteus TY-3。文章对菌株TY-3的酶学性质进行研究,结果显示该菌漆酶酶活最适温度为35℃,热稳定性在20~30℃条件下最好;最适pH值为2.5,在2.0~3.0之间维持着较高的酶活,但pH值超过3.0后酶活急剧下降;Co^(2+)、Mg^(2+)、Zn^(2+)、Cu^(2+)、Ag^(+)金属离子对漆酶与ABTS反应有激活作用,其中Co^(2+)、Mg^(2+)作用最明显,而Fe^(2+)对漆酶和底物ABTS反应有严重的抑制作用。文章的研究结果丰富了产漆酶微生物的种质资源库,为漆酶的工业化应用提供理论依据。     

2，3-环戊烯并吡啶的气相色谱分析

通过对色谱分离条件的优化,建立了2,3-环戊烯并吡啶的气相色谱分析方法。色谱条件为SE-30毛细管色谱柱(25 m×0.22 mm×0.25μm);载气(N2)流速为1.0 mL/min;柱温为130℃;进样器温度为200℃;分流进样模式,分流比为100∶1。对合成样品进行了测定,线性回归方程为A=440.84c+33 088,r=0.999 3,线性范围为2~500 mg/L,方法的检出限为0.2 mg/L,平均回收率为99.4%,相对标准偏差为1.30%。     

污水中离子对恒聚聚合物溶液粘度的影响研究

通过蒸馏水配制恒聚聚合物母液,不同含量的离子溶液稀释恒聚聚合物母液后的粘度变化,研究油田污水中的常规离子Na~+、Ca~(2+)、Mg~(2+)、S~(2-)、Fe~(2+)对恒聚聚合物溶液粘度的影响。通过恒聚聚合物溶液粘度的影响实验,对比恒聚聚合物溶液粘度保留率为60%时各离子需要达到的浓度,得出污水中常规离子对恒聚聚合物溶液粘度的影响顺序是Fe~(2+)>S~(2-)>Mg~(2+)>Ca~(2+)>Na~+,同时考虑胜利油田化学驱单元污水中的离子含量,确定影响恒聚聚合物溶液粘度的主要因素是Fe~(2+)和Na~+,要提高恒聚聚合物溶液的粘度需要考虑除去Fe~(2+)和抑制Na~+对聚合物分子的卷曲作用。     

顶空-气相色谱法测定地下水中苯和甲苯的方法研究

采用美国PE气相色谱仪及其附带的顶空进样器,DB-17色谱柱,FID检测器,建立了顶空-气相色谱法测定地下水中苯和甲苯含量的方法。研究表明,在顶空平衡温度80℃下平衡30 min,进样时间0.04min,色谱柱温度50℃,载气流速2mL/min条件下,苯和甲苯的分离效果最佳,在0～100μg/L范围内,其线性相关系数分别为0.9980和0.9994;方法检出限分别为0.099μg/L和0.220μg/L;方法定量限分别为0.40μg/L和0.88μg/L;回收率分别在99.0%～101%、90.5%～99.0%。     

β-D-半乳糖苷酶活性测定方法的研究

应用分光光度计建立一种简便检测β D 半乳糖苷酶(GAL)活性的方法。酶反应条件研究表明,在总体积为1mL的0.1mol/L柠檬酸反应缓冲体系(pH值为4.5)中含0.8μmol的底物邻硝基苯β D 吡喃半乳糖(ONPG),含相当于2mg左右蛋白质的酶提取液,37℃孵育30min后用0.5mol/L碳酸钠1mL终止反应,用紫外分光光度计于405nm波长测定的吸光度值最能反映该酶活性。结果显示,该方法的批内变异系数在3.92%～4.89%之间,批间变异系数为3.8%,均小于5%;在所检测该酶质量浓度范围(1～2.5mg/mL)内线性关系良好,当反应体系的蛋白含量低于0.5mg/mL时,酶活性不能被检出;每组的平均回收率均在95%～105%之间,说明在所检测浓度范围内回收良好。因此,该方法具有稳定性好、灵敏度高、简便易行等特点,适合一般实验室应用。     

两性霉素B菌种选育及发酵工艺研究

为了提高两性霉素B(amphotericin B,AmB)的产量,降低生产成本,满足市场需求,采用紫外诱变和常压室温等离子体(atmospheric and room temperature plasma, ARTP)诱变的复合诱变方法进行菌株选育。首先,对结节链霉菌出发菌株A318-10进行复合诱变;然后,筛选高产菌株,并利用软件Design-Expert 12对显著效应因子进行Box-Behnken Design试验设计,得到最优发酵配方;最后,在1 L摇瓶及50 L发酵罐中进行发酵优化配方验证。结果表明,在紫外诱变60 s并ARTP诱变35 s后,筛选得到了高产菌株20-2-15,其最优发酵配方为葡萄糖94.6 g/L、中温豆粉27.7 g/L、淀粉24.1 g/L;在最优配方下,结节链霉菌1 L摇瓶和50 L发酵罐的发酵最高水平分别为18 968μg/mL和21 257μg/mL,比原始配方分别提高了32.6%和29.4%。研究结果应用于规模化生产后,有利于降低成本、提高企业竞争力。     

青风藤配方颗粒的制备及与传统汤剂的比较

为了研究青风藤配方颗粒制备工艺以及对青风藤配方颗粒与传统汤剂进行定性定量比较,运用正交试验方法,采用干法制粒,以出膏率、青藤碱含量为指标,优选青风藤配方颗粒制备工艺;采用薄层色谱法进行定性比较;以青藤碱为对照品,采用高效液相色谱法进行定量比较。青风藤配方颗粒最佳制备工艺如下:提取2次,加水量18倍(第1次加水量为10倍,第2次加水量为8倍),各煎煮1.0h。TLC结果显示,配方颗粒与传统汤剂化学成分的类型无明显差异。5批青风藤配方颗粒青藤碱含量分别为1.56%,1.58%,1.31%,1.20%和1.78%;5批青风藤传统汤剂青藤碱含量分别为0.94%,0.96%,0.85%,0.82%和1.02%。青风藤配方颗粒与传统汤剂中化学成分的类型基本相同,但青藤碱含量差异较大。     

On the Intricacies of the Chinese Guanxi: A Process Model of Guanxi Development

Guanxi (personal connection) has been identified as a necessary condition to do business successfully in China. In this paper, we seek a clear conceptual understanding of this prevalent construct and propose a three-stage model of guanxi development so as to stimulate systematic research in this area. Our conceptual and theoretical discussion of guanxi bases,guanxi objectives, and the operating principles at different stages of guanxi development will also help practitioners to use guanxi more effectively.     

Firm Growth Under Sample Selection: Conditional <Emphasis>σ</Emphasis>-Convergence in Firm Size?

This paper tests the second, widely neglected implication of Gibrat’s law stating that the variance of firm size distribution increases over time. In contrast, learning models imply conditional σ-convergence in firm size. A unique data set of Austrian firms especially suited to account for sample selection effects is used to analyze the growth/size nexus of firms. The estimation results suggest that the predicted variance in firm size decreases only for firms of age 30 or below. For older age cohorts the hypothesis of a constant variance either cannot be rejected or increasing variances are found.     

The uniform distribution as a first practical approach to new product inventory management

It is common sense that the premises usually considered in inventory models have little applicability to new product inventory management. This paper develops a first practical approach to deal with this issue: the solution to the (Q, r) inventory model for uniform demand forecasts and lead-times. Based on the fact that the uniform distribution is defined by two parameters that are easy to estimate—maximum and minimum—this paper shows that such a premise may comprise a helpful and accurate decision support tool for managers until they begin to learn about the distribution characteristics of the demand during the lead-time.     

Getting consumers to eat more whole-grains: The role of policy, information, and food manufacturers

The 2005 Dietary Guidelines were unique because they offered quantitative recommendations for consumption of whole-grains. This case study examines the hypothesis that the changed recommendations were responsible for the recent increase in retail sales and consumption of whole-grain food products. We find that release of the Dietary Guidelines and related media attention did increase availability and sales of whole-grain foods. A large impact on consumption occurred through reformulation of existing products, induced by competition among food suppliers. This study reveals the key role product reformulation plays in inter-firm competition and in realization of dietary changes recommended by public policy.     

Gibrat's Law: Are the Services Different?

Several noted surveys on intra-industry dynamics have reached the conclusion from a large body of evidence that Gibrat's Law does not hold. However, almost all of these studies have been based on manufacturing or large scale services such as banking and insurance industries. There are compelling reasons to doubt whether these findings hold for small scale services such as the hospitality industries. In this paper we examine whether the basic tenet underlying Gibrat's Law– that growth rates are independent of firm size – can be rejected for the services as it has been for manufacturing. Based on a large sample of Dutch firms in the hospitality industries the evidence suggests that in most cases growth rates are independent of firm size. Validation of Gibrat's Law in some sub-sectors of the small scale services suggests that the dynamics of industrial organization for services may not simply mirror that for manufacturing. The present paper includes a survey of nearly 60 empirical studies on firm growth rates.     

杜仲不同炮制品配方颗粒的红外快速鉴别

为快速鉴别杜仲不同炮制品配方颗粒,建立了红外光谱法,结合二阶导数光谱及二维相关光谱法,分析不同炮制品配方颗粒的光谱特征。结果表明:杜仲不同炮制品配方颗粒的红外光谱基本相似,仅在1 603,1 514,1 420cm~(-1)处出现位置变化;在800~1 600cm~(-1)范围内,二阶导数光谱吸收峰有明显的强度、形状、位置变化;1 800~1 000cm~(-1)范围内,二维相关光谱差异明显。通过比较杜仲不同炮制品的红外光谱图、二阶导数光谱图及二维相关光谱图,可以准确、快速地鉴别杜仲不同炮制品配方颗粒。     

Knowledge and Values in Technology Education

This paper addresses two closely interrelated issues in Technology Education: knowledge and values. The starting point for the discussion is analysis of the nature of knowledge in technology education. Approaches for theorising knowledge will be analysed in this paper as well as problems associated with them. Three major types of problems are identified: problems with finding an appropriate approach for the analysis of technological knowledge; problems with a technocratic interpretation of technological knowledge for the purpose of its classification; and problems with establishing a consistent approach to distinguish common features of technological knowledge. A model that represents knowledge in technology education and the place of values in it is presented as a way of overcoming the problems specified. The claim is made that understanding of knowledge/values relationships can improve theoretical understanding of how technology education can be constructed.     

瓜蒌配方颗粒指纹图谱研究

为了全面反映瓜蒌配方颗粒所含多种组分,明确瓜蒌配方颗粒HPLC指纹图谱的测定方法,对10批瓜蒌配方颗粒进行了HPLC指纹图谱测定及相似度评价。采用HPLC方法,色谱柱为GL Sciences公司InertSustain AQ-C_(18)柱(4.6 nm×250 nm,5μm),以甲醇-0.1%甲酸水溶液为流动相,梯度洗脱,检测波长为260 nm,流速为0.8 mL/min,柱温为25℃,对瓜蒌配方颗粒指纹图谱测定结果进行了相似度评价。结果表明,10批瓜蒌配方颗粒指纹图谱中呈现16个共有峰,相似度均大于0.960,表明瓜蒌配方颗粒具有良好的一致性;此外,在16个共有峰中指认出腺嘌呤、尿苷2个化学成分。瓜蒌配方颗粒指纹图谱反映了瓜蒌配方颗粒的多组分面貌,可为瓜蒌配方颗粒的多组分质量控制提供参考依据。