超声水提秦艽中龙胆苦苷的工艺优选

优选出秦艽中龙胆苦苷的提取最佳工艺,采用正交试验法,以龙胆苦苷的质量分数为指标,考察了溶剂用量、提取时间、提取次数及提取温度对秦艽中龙胆苦苷提取率的影响,优选出合理的提取工艺。结果得知,蒸馏水用量为15 mL、提取时间为40 min、提取次数为2次、提取温度为40℃为最佳工艺条件,经验证性实验证明所优选条件可靠,适合秦艽中龙胆苦苷的提取。     

舒筋通络颗粒中乳香挥发油提取及包合工艺研究

为提高乳香挥发油在制剂中的稳定性,对舒筋通络颗粒中乳香挥发油的提取及其包合工艺进行了研究。选择浸泡时间(A)、药材粒径(B)、加水量(C)、提取时间(D)为考察因素,采用L_9(3~4)进行正交试验设计,优化乳香挥发油的提取工艺,通过正交试验,对饱和水溶液法和胶体磨法两种包合方式进行了工艺研究。结果表明:影响因素的优化组合为A_1B_1C_1D_3,其中加水量和提取时间对收率具有极显著性影响,包合时间、挥发油和β-环糊精比例、包合温度对饱和水溶液法有极显著性影响;研磨时间、挥发油和β-环糊精比例对胶体磨法有极显著性影响。从生产角度考虑,包合乳香挥发油采用胶体磨法较饱和水溶液法更具有优势。     

溶剂法提取酸菜中亚硝酸盐的研究

利用水、果蔬剂、10%(体积分数)乙醇、NH<,3>-NH<,4> Cl缓冲溶液、2%(体积分数)醋酸溶液、2.0 mol/L的KCI提取酸菜中的亚硝酸盐并与国标法进行了比较.亚硝酸盐含量的测定采用盐酸萘乙二胺比色法.实验结果表明,10%(体积分数)乙醇作提取剂时,所测得的亚硝酸盐含量与国标法有显著差异,而用其余的溶剂...     

供电所技能竞赛试题(七)

(总分100分)一、单项选择题(每题1分,共15分)1.穿管明敷设的线路,钢管壁厚不小于()毫米。A0.8B1.0C2.0D3.02.低压电力线路与弱电线路交叉时,电力线路与一级弱电线路的交叉角不小于()度。A35B40C45D503.铁壳负荷开关应按负荷额定电流的()倍选择。A1～2B2～3C2～4D3～44.巡线人员发现导线断落地面或悬吊空中时,应设法防止行人靠近断线地点()米以内。A3B5C6D85.安装电容器的环境,一般相对湿度应不大于()%。A65B75C85D956.供电区域内设备管理要分工明确,责任到人,对设备缺陷必须做好记录,并按()分类处理。A缺陷等级B设备等级C电压等级…     

溶剂法提取香薷黄酮化合物的研究

采用溶剂法提取香薷中黄酮化合物,并进行单因素工艺考察,筛选出最佳的提取条件.在单因素基础上,利用响应面分析法考察乙醇浓度、提取温度及物料比对提取香薷总黄酮的影响,并在各影响因素合理值内修正最佳工艺条件.结果表明,香薷总黄酮最佳提取工艺条件为提取时间1h,乙醇体积分数70％,提取温度70℃.     

供电所技能竞赛试题(十二)

(总分100分)一、单项选择题(每题1分,共20分)1.电流的基本国际单位是()。A焦耳B瓦特C安培D伏特2.电压保护装置的电气文字符号是()。A PV B APAC APD D APR3.测量仪表的误差可分为()。A测量误差和基本误差B基本误差和相对误差C基本误差和附加误差D绝对误差和相对误差4.我国采用的工业频率(简称工频)为()HZ。A50B60C80D1005.下列高压电器属于补偿电器的是()。A互感器B电容器C断路器D交流接触器6.在低压供电线路中,若计算回路中的负荷电流为()及以下时,应采用直接接入式的三相四线有功电能表进行计量。A40A B50AC80A D100A7.…     

正交试验法优选超临界CO2流体萃取丹参中丹参酮工艺的研究

研究了超临界CO2流体萃取法萃取丹参中丹参酮的最佳工艺条件,以丹参酮ⅡA含量为指标,用高效液相色谱法测定,采用L9(34)正交试验法对丹参中丹参酮的提取工艺进行优选。结果表明,萃取压力对萃取结果影响最为显著,最佳萃取压力为25 MPa,萃取温度为40℃,无水乙醇用量为30%(质量分数),萃取时间为2 h。     

供电所技能竞赛试题(九)

一、单项选择题(每题1分,共10分)1.电功率的大小与()无关。A时间B电压C电流D电阻2.线路检修挂接地线时,应先接()。A接地端B A相C B相D C相3.已知一钢芯铝绞线钢芯有7股,每股直径2.0毫米,铝芯有28股,每股直径2.3毫米,其导线型号为()。A LGJ-240/50B LGJ-185/25C LGJ-150/25D LGJ     

供电所技能竞赛试题(四)

一、单选题(每题1分,共10分)1.若触电者心跳停止,呼吸尚存,应立即对触电者施行()急救。A仰卧压胸法B仰卧压背法C胸外心脏挤压法D口对口呼吸法2.当停电检修线路与另一回10千伏及以下带电线路交叉邻近的距离小于()米时,另一回带电线路也应停电并挂接地线。A1B1.5C2D2.53.防止雷电     

供电所技能竞赛试题(三)

一、单项选择题(每题1.5分,共45分)1.已执行的工作票由供电所保存,保存期()个月。A2B3C6D122.在人身触电伤害赔偿范围中,在计算当事人的亲友参加处理事故所需费用时,计算人数不超过()人。A2B3C4D53.自电杆引下的接户线和室外进户线最小线间距离一般不小于()毫米。A100B150C200D3004.用电功率因数的高低,直接关系到供电的电压质量。因此,提高功率因数,做到无功电力就近供应,就地平衡,是一项极重要的()措施。A补偿B节能C计划5.挂接地线时,若杆塔无接地引线时,可采用临时接地棒,接地棒插入地面深度应不小于()米。A0.5B0.6C1.06.供电企…     

醇胺类离子液体的合成及表征

由乙醇胺、二乙醇胺、三乙醇胺提供阳离子,甲酸、乙酸、乳酸提供阴离子,合成了一系列醇胺类离子液体,并对其进行了核磁共振氢谱和红外光谱表征并确认。将常规水浴法、冰水浴法、微波法进行比较,并对水浴条件下反应温度、反应时间对收率的影响进行了考察。最佳反应条件如下:反应时间为20 h,水浴温度为5℃。     

Employee Reactions to Supervisory Direction in Four Types of Firms in Taiwan: The Effects of Company Policy, Peer Consensus and Independent Assessment

Employees in four firms in Taiwan—a small family business (A), a state-owned enterprise (B), a large private corporation (C), and a U.S.-owned venture (D)—and one firm in the U.S. (E) responded to supervisory directions. A's employees were the most compliant, followed by B's, then by C's, D's, and E's. In A and B, employee compliance was impacted by company policy. In C, D and E, employee compliance was influenced by peer consensus. Except for those in A, employees' tendency to accept supervisory direction was enhanced when they assessed the direction as beneficial to their organization.     

某城市排污河水质状况分析评价

以城市排污河道为研究对象,测定了表层沉积物中的重金属总量、水质常规指标及DBP和DEHP,采用改进的主成分分析法和等标有机污染指数分析对排污河污染状况进行分析评价。运用改进的主成分分析法找出了主要污染源和主要污染物。结果表明:不同排污口的主要污染物不同,B化工厂CODCr及pH值为主要污染物;C泵站污染严重的为CODCr,pH值和TP;D排污口主要污染物为CODCr,NH3-N,Cr和pH值;E化工厂的主要污染物为CODCr,NH3-N和Cd。D排污口是第一主成分的主要污染源点,B化工厂无论是DBP等标污染指数还是DEHP等标污染指数均明显高于其他排污口,是A排污河PAEs污染的主要污染源。     

桔皮中黄酮类化合物的提取方法研究

采用单因素实验和正交试验方法,以桔皮中黄酮类化合物的收率为考察指标,对影响桔皮中黄酮类化合物提取方法的因素进行了探讨,并测定了桔皮中黄酮的含量。结果表明:浸提温度为70℃,乙醇浓度为70%(体积分数),提取时间为2 h,物料质量比为1∶40为最佳提取条件;在确定的最佳提取条件下,黄酮收率为1.68%。     

How Do Interaction Activities among Customers and between Customers and Firms Influence Market Performance and Continuous Product Innovation? An Empirical Investigation of the Mobile Application Market

Mobile application markets (MAMs) significantly differ from other existing marketplaces at least in two aspects. First, customers (app users) and firms (app providers) frequently interact with each other in real time, which is not common in the conventional marketplaces. Second, many app providers incorporate customers’ opinions or suggestions into their software upgrades, representing one of the most unique and interesting aspects of MAMs. Therefore, it has become critical to understand the impact of interaction activities not only among customers, but also between customers and firms on the market performances of new products in MAMs. One of the most significant issues firms face is whether firms reflect on customers’ postpurchase interaction activities, and the next interesting question is how firms respond to them. This study explores the effects of customer‐to‐customer (C2C), customer‐to‐firm, and firm‐to‐customer interaction activities on market performance. In addition, this study investigates how communication activities influence a firm's tendency to pursue continuous product innovation through research and development (R&D). Using data obtained from a major MAM, T store, three models that are respectively related to product sales, product lifetime, and a firm's R&D activity for product upgrades, are applied to empirically test hypotheses concerning the effects of interaction activities. In our analyses of market performance, a hierarchical log regression model with 10,840 weekly transactions data set related to product sales (model A) and 291 aggregate transactions related to product lifetime (model B) is used. Results indicate that C2C and customer‐to‐firm communication activities have a positive impact on sales, but little relationship with product lifetime. However, a firm's continuous product R&D has a positive impact on both sales and lifetime performance. Our analysis of a firm's R&D (model C) shows that C2C and customer–firm communication increases a firm's R&D activity. Taken together, these results have important implications for customer–firm interactions, market performance, and R&D strategies.     

薯蓣皂甙元提取方法的研究进展

薯蓣皂甙元是薯蓣皂甙的水解产物,它是许多重要甾体激素的前体物质。介绍了薯蓣皂甙元的结构、化学组成和近年来的提取方法,综合比较了常规酸水解法、自然发酵法、超声法、酶水解法、超临界流体萃取法等方法的优缺点,认为超临界流体萃取法较为先进且对环境无污染,并对今后的研究方向提出了展望。     

超声波破解污泥的试验研究

研究了超声波破解污泥的情况。在超声波单独作用及超声波/碱作用下,测定SCOD(溶解性COD)的量,分析超声波、超声波/碱对污泥破解的效果。结果表明,从镜检中可以看到,污泥絮体随超声波作用时间的延长越来越散;SCOD随超声波作用时间的延长而增加;超声波与碱协同作用对污泥的破壁效果比超声波单独作用好。     

E-Procurement adoption in the Southcoast SMEs

E-Commerce is expected to play a major role in the 21st century global market. Of the various E-commerce models (B2B, B2C, B2E and B2G), B2B has been particularly successful, due to adoption of standardized processes for document exchange (like EDI), shipping, tracking, delivery and payment among supply chain partners. One element of B2B is E-procurement. E-procurement focuses on acquisition of resources, especially MRO items, and increasingly materials and components. Some analysts believe that enormous cost savings and increased effectiveness can be achieved through the utilization of E-procurement. E-procurement utilizes electronic purchase procedures implemented through Internet communication and Web based buying tools. Studies in the literature report on the adoption of E-procurement in different countries and industries. This study focuses on the current status of E-procurement in small and medium sized enterprises (SMEs) located in the Southcoast of Massachusetts. The main objective of this research is to understand the current state of E-procurement in SMEs and to examine those things that influence E-procurement adoption. A questionnaire-based survey was employed for data collection. A conceptual model was developed to describe/explain the adoption of E-procurement and a framework is proposed for the successful adoption of E-procurement on the Southcoast of Massachusetts.     

Book Reviews

Book reviewed in this article:
Consciousness and Action among the Western Working Class, by Michael Mann
Grundrisse: Foundations of the Critique of Political Economy (Rough Draft), by Karl Marx
Self-Government in Industry by G. D. H. Cole, edited by J. Corina
Workshop Organisation by G. D. H. Cole, edited by A. Marsh
Unemployment and Politics: A Study in English Social Policy, 1886–1914 by José Harris
Evaluating the Impact of Manpower Programs edited by Michael E. Borus
Economic Aspects of Manpower Training Programs by D. Hamermesh
Organization Design: Tlieory and Practice by Peter A. Clark
Sociology and Industrial Life by J. E. T. Eldridge
Man and Organization edited by John Child. George Allen & Unwin
Employment Conditions in Europe by Margaret Stewart
The P.E. Briefing Guide to Wages and Employment in the E.E.C     

超声波在化学工业中的应用

介绍了近年来超声波在化学工业中的应用与进展,以及超声波的特征和超声波促进化学反应的基本原理,较为全面地总结了超声波在有机合成、聚合反应、结晶过程、萃取分离、超细粉体制备等方面的国内外应用情况,总结了超声外场付诸于化学工业所遇到的主要困难是对于超声化学理论知识的研究还不够成熟以及缺乏适用于工业化生产的超声化学反应器,提出解决问题的关键是需要大量学者对超声化学的反应机理方面进行更加深入的研究与探索。指出超声外场是一种新型的催化体系,超声化学具有广阔的应用前景。