双环戊二烯与苯乙烯共聚的研究

采用Grubbs催化剂进行双环戊二烯开环移位聚合,重点考察了本体聚合及双环戊二烯与苯乙烯共聚的影响因素,并利用红外光谱和差示扫描量热仪对产物的结构与性能进行了表征。结果表明,对于双环戊二烯本体聚合及双环戊二烯-苯乙烯共聚合体系,随着聚合温度的升高,反应速度增加,凝胶时间变短,但最终单体转化率基本不变;随着催化剂浓度的降低,体系凝胶时间延长。双环戊二烯与苯乙烯的配比对凝胶时间及转化率影响不大,但过量苯乙烯的引入会导致产物玻璃化温度的下降。     

Consumers' quality choices during demand peaks

In a number of product categories, average prices decrease when demand exogenously increases. The literature disagrees on whether this effect is due to firms' reactions to high demand or to changes in consumer behavior. I propose a strategy that enables the identification of supply and demand movements by examining unpredictable and short-lived exogenous demand shocks. During these periods, firms do not have time to adjust pricing or advertising strategies, and most activity comes from changes in consumer behavior. My model shows that during periods of exogenous high demand, consumers migrate toward cheaper, lower-quality products. I focus on ice cream purchases, which have a seasonal peak during the summer and increase during less-predictable periods of unseasonably high temperatures. Using individual-level data, I test model implications and estimate structural parameters, finding evidence consistent with consumers' quality shifts. I also reject alternative supply-side theories' explanations for the main drivers of the observed price dynamics.     

溶胶-凝胶法制备锑掺杂氧化锡纳米粉体

锑掺杂二氧化锡(antimony-doped tin oxide,ATO)是优良的催化剂,具有良好的导电性和高温稳定性。采用溶胶-凝胶法制备ATO纳米粉体,并对其进行结构分析和性能表征。以金属锡粉和三氧化二锑为金属原料,制备得到柠檬酸锡、锑的配合物溶液,向其中加入乙腈,产生溶胶-凝胶过程。对洗涤后的凝胶进行不同温度热处理,得到锑掺杂氧化锡纳米粉体。随着锑掺杂量的增加,纳米粉体的晶粒减小,比表面积增加,晶胞参数也发生相应变化。随着热处理温度的升高,纳米颗粒长大,比表面积减小,高锑掺杂量的氧化锡纳米粉体显示出结晶性下降的趋势。     

可逆热致变色油墨的色度学特性研究

本文研究了活化温度为31℃的3种含隐色染料基的热致变色油墨的色度学特性。这3种油墨具有相似的颜料粒径分布和同等厚度且对氧等离子体腐蚀相对稳定的微胶囊壳。油墨颜色与温度、引起颜色滞后的样品热史两个因素有关。比较脱色和着色过程,在CIELAB色空间中所观测的滞后环面积决定了样品上色差的大小。同一样品所能达到的最大色差是由样品不同的热史和温度决定。4个特征温度描述了引起颜色滞后的2个化学反应。当冷却到低于活化温度时,脱色状态的稳定性超过10h。热致变色效应的可逆性随着最高加热温度约呈线性降低。     

Thinking one step ahead: The use of conjectures in competitor analysis

An assessment of opponents' reactions to strategic and functional area policy decisions is shown to require knowledge concerning opponents' beliefs about the firm's behavior. This study introduces a methodology for incorporating such conjectures into the business planning process. It presents an analytical measure for these conjectural variations and discusses several illustrations. Examples of the application of the framework are provided by the Japanese flat glass industry and the U.S. domestic coffee roasting industry. The use of a broad range of conjectural variations in competitor analysis is discussed, and implications for business strategy formulation are highlighted.     

A Conjoint-based Product Designing Procedure Incorporating Price Competition

Conjoint analysis has become a major tool in the process of designing and concept testing consumer packaged goods and industrial products. In most applications, however, product concepts are tested against existing sets of competing brands without considering potential competitive reactions. Although many researchers have recognized the need for models to incorporate competitive reactions, few methodological developments have been published thus far. Instead of what-if analysis, which depends heavily on the managers' intuition about the competitors' reactions, S. Chan Choi and Wayne DeSarbo propose a game theoretic approach that models competing firms' reactions in price. This price reaction model is incorporated in the conjoint simulator for evaluating product concepts against competing brands. They illustrate the methodology using a commercial data set previously collected.     

Big splash,no waves? Cognitive mechanisms driving incumbent firms’ responses to low‐price market entry strategies

Research Summary: Low‐price market entries, aiming for rapid sales growth, tend to prompt strong competitive reactions. This research explores whether and how firms using low‐price entry strategies can mitigate retaliatory incumbent reactions. An experiment with 656 managers shows that entrants can attenuate the strength of incumbents’ responses by fostering perceptions of high aggressiveness or low commitment. Entrants may be able to accomplish this by adjusting their entry strategy to embed (subtle) cues of aggressiveness and (lack of) commitment. A replication experiment with university students reinforces our overall theoretical argument. However, the results also indicate that the interpretation of cues embedded in the entry strategy may be affected by the experience of incumbent firm managers. Overall, these results clarify the cognitive foundations of competitive responses to market entry. Managerial Summary: What drives incumbents to respond strongly to market entries, and what can the entrant, if anything, do to mitigate those responses? This research offers empirical evidence and theoretical insights for managers faced with these questions by shedding light on the thinking processes preceding competitive responses. The study shows that while managers are motivated to respond strongly to market entries that appear to be highly consequential to their business, these responses may be mitigated if the entrant manages to foster perceptions of high aggressiveness or low commitment to the market. Managers form these perceptions in part on the basis of the entrant’s behavior, creating an opportunity for entrants to adjust their entry strategies in a manner that demotivates strong competitive responses.     

Capital Structure Theory: Evidence from European Property Companies' Capital Offerings

This study examines the stock price reactions on announcements of both equity and debt offerings by European property companies. The unique setting in which corporate tax rates vary between different countries enables us to test established theories in the field of capital structure. In accordance with theory, we find a negative price reaction on equity offering announcements, which is less severe for low-tax countries and positive price reactions on the announcements of debt offerings. Besides tax arguments, we also test alternative explanations by analyzing variations in stock reactions based on differences in the relative size of the issue, the pre-offer leverage, the underlying property types, and operational performance. The results show that corporate taxation, issue size, and operational performance are significant explanatory factors in the negative price reactions.     

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。     

L-脯氨酸催化的不对称直接Aldol反应

着重介绍了L-脯氨酸催化不对称直接Aldol反应的特点及反应类型,认为L-脯氨酸及其类似物催化的不对称直接Aldol反应不仅具有理论上的研究价值而且具有潜在的工业化前景。     

离子液体在生物酶催化反应中的应用进展

综述了离子液体在生物酶催化反应中的应用,包括酯化反应、氨解反应、氧化反应、还原反应、Aldol反应和水解/醇解反应等,在这些反应中,离子液体通常起到了提高酶的活性或稳定性,并提高产物收率和选择性的作用。总结了离子液体中酶催化反应的机理,分析了离子液体提高酶的活性和稳定性的原因,指出了现阶段研究中存在的问题和未来努力的方向。     

焊接条件对高强钢HAZ断口形貌的影响

本文应用插销试验法研究了焊接条件——钢材种类、扩散氢含量、预热温度和后热温度对航空常用三种高强钢30CrMnSiA、30CrMnSiNi2A和40CrMnSi MOV HAZ 冷裂倾向的影响,并通过断口扫描分析探讨了焊接条件对 HAZ 断口形貌的影响。试验证明,焊接条件改变,HAZ 的冷裂倾向和断口形貌均发生较大的变化。     

己内酰胺废水处理过程中ENSBR反应池中的pH值变化规律

在己内酰胺废水处理过程中,通过对ENSBR反应池中pH值及相关水质参数的变化进行分析,可知pH值变化是由有机物氧化反应、氨化反应、硝化反应、反硝化反应和污泥消解反应等引起的,并且是上述5个反应在不同反应条件下的综合作用结果。     

经济发展和气温升高——基于中国直辖市和省会城市面板数据的实证研究

气温升高已经成为困扰人们经济生活的主要问题,因此研究导致气温升高的原因显得特别重要。文章尝试利用我国直辖市和省会城市面板数据研究经济发展对气温升高的影响,分别利用全国样本数据和分地区样本数据,实证研究发现我国经济增长和经济结构均是导致气温升高的原因。同时也发现经济发展对气温升高的影响具有外部性,即周边地区的经济发展也会导致省会城市的气温升高,因此气候问题只有各地区通力合作才能得以治理。     

A comparative analysis of layoff announcements and stock price reactions in the United States and Japan

Downsizing and layoffs are an important mechanism for U.S. firms to cope with their strategic and economic environment. In contrast, the Japanese tradition of lifetime employment limits the ability of firms to employ layoffs as a strategic measure, relegating its use to conditions of financial distress. This paper provides the first comparison of layoffs in Japan and the United States and examines stock price reactions to layoff announcements in each country from 1990 to 1994. Agency theory and Aoki's cooperative game theory are employed to discuss differences in the governance structures of U.S. and Japanese firms and their implication for stock price reactions. Results show that layoff announcements trigger negative returns for both U.S. and Japanese firms. Specifically, layoff announcements of U.S. firms are associated with a negative 1.78 percent abnormal return, while layoff announcements for Japanese firms are associated with a negative 0.56 percent abnormal return. To better understand the impact of layoffs, this study examines the relationships between stock price reactions and various layoff characteristics (such as whether the layoff is proactive or reactive or whether the layoff is the first in the industry). Implications of the findings are discussed. © 1997 John Wiley & Sons, Ltd.     

Explaining Competitive Reactions to New Products: An Empirical Signaling Study

This article develops a conceptual model to help explain the strength of competitive reactions to new product introductions and presents the findings from a preliminary empirical investigation of this model. Being able to explain the strength of competitive reactions to new product introductions is important, as such reactions often determine a product's success or failure in the marketplace. To explain these reactions Oliver Heil and Rockney Walters investigate competitive market signals associated with new product introductions and the reactions of competing firms to the signals. The authors empirically test the hypothesized linkages among three market signals—hostility, consequences and commitment—and competitive reactions using primary data collected from a large number of US corporations. The empirical results show that the market signaling variables explain a significant portion of the variance in the perceived strength of competitive reactions to new product introductions. The study has implications for managers introducing new products and for researchers studying new product introductions and competition.     

有机小分子催化的不对称直接Aldol反应研究新进展

对近些年来L脯氨酸(LProline)等6类有机小分子催化剂催化不对称直接Aldol反应的特点、实用范围及结果作了详细介绍,认为该领域具有广阔的发展前景。     

The Role of Objective In Vivo Testing in the Product Development Process

New products managers are continually confronted by the challenge of coordinating flows of complex information during the product development process. Among the issues faced are unique problems in relating technical design of product attributes to customers' reactions, leading to an improvement of the product's benefits. Ronald Drozdenko and Sidney Weinstein describe a variety of tests which help to assess customers' reactions to products, thus providing information to improve the design or to substantiate advertising claims. The term "objective in vivo" is given to a category of tests which is employed to quantify consumers' evaluation of specific product attributes under controlled, simulated use conditions. This helps to bridge the gap between tests which are designed to measure the physical or functional aspects of new products and tests which measure the consumers' self-reported, subjective reactions. A test categorization model, illustrative case studies, and test selection criteria are presented.     

Batch runaway reaction relief: Re-evaluation of “Credible” scenario

Many chemical reactions in the fine chemical and related industries are performed in a semi-batch manner under isothermal conditions. Relief system design evaluation for runaway reactions, using DIERS methodology for example, is frequently studied adiabatically using data derived from batch mode testing. In many cases, however, evaluation of the process isothermally under the realistic semi-batch mode can be extremely useful, often helping to greatly reduce the vent size as a result of a better understanding of the process. In some cases, it is even possible to eliminate runaway reaction as a viable case for relief sizing. Such evaluations of venting are fully consistent with DIERS methodology. This paper presents the arguments for sizing vents for scenarios other than the very worst case, by objective evaluation of trips and interlocks, so that the level of risk is reduced to an acceptable level without the need for extremely large vents.     

Linking Innovation to Design: Consumer Responses to Visual Product Newness

In recent years, researchers have begun to recognize the central role that visual design plays in successful marketing efforts. However, little research has effectively bridged the gap between product innovation and visual design. Before consumers can judge the competitive newness of a product based on its functionality, they first encounter its visual form. Therefore, both innovation researchers and product managers need to be aware of the impact that visual design can have in communicating product newness. In the present work, two studies are described that examine consumers' responses to visual product newness. The first study explores the ability of consumers to recognize and assess product newness using visual design cues and then examines the basis on which these evaluations are made. The second study examines the cognitive and affective reactions that are engendered by exposure to products that are high in visual product newness.