子宫输卵管造影术126例观察及护理

子宫输卵管碘油造影术是治疗不孕症常见也是最有效的办法之一,而正确的护理是促进手术成功的重要方面,本文根据我院实例介绍,探讨了子宫输卵管碘油造影术的观察和护理工作。     

电动汽车所用电控系统性能介绍及设计

本文简要介绍电动汽车所用电机控制器的种类、结构、工作原理、特点和设计。     

Learning design and technology through social networks for high school students in China

The subject of design and technology was introduced to the curriculum for high schools in China 10 years ago. However, the teaching and learning of this subject have become difficult for both teachers and students because there is a lack of qualified teachers with design background to deliver this subject in a way to stimulate the learning interests of the students. This paper presents a research that is aimed at improving this situation by integrating the teaching and learning of design and technology within a computational environment as part of social networks sites. The purpose is to enable the collaboration among the students and interaction between teachers and students. In this research, a series of investigations were conducted, by following through several taught subjects in design and technology in prominent high schools in China. Based on these investigations, a theoretical framework for web-based design learning and teaching system in the style of social networking is developed, implemented and tested, emphasizing three features of design: innovation, collaboration, and interaction. This framework has been tested among high school students and teachers in a high school in Nanjing. It identified and validated necessary techniques and design features required to make an education-related social networking site effective and affective for the students and teachers. The results of this research indicated that social networking sites have significantly positive values in design education, especially for the collaboration and interaction on the subject of design and technology.     

催化裂化反应过程分析

催化裂化是石油深加工的重要手段,是汽油、柴油、液化气等轻质产品的主要生产过程,在炼油工业中占有核心地位。大约85%的汽油和30%的柴油产自催化裂化。现就催化裂化反应过程进行简要分析。     

基于D-S证据理论的校园交通环境评价方法研究

从环境受用者的感受出发,将不确定性评价方法,即基于D-S证据理论的融合决策方法应用于校园交通环境评价中.该方法考虑各类环境受用者的感受差异,用融合的方法得出环境受用者的综合感受评价值,再结合环境评价的其它量化评价指标,能够使得评价结果更加客观和准确.     

基于信息一体化的仓储物流系统网上平台设计和实现

在分析仓储物流系统重要性的基础上,阐述了基于信息一体化的仓储物流系统网上平台的内涵与特点,论述了基于信息一体化的仓储物流系统网上平台的设计理念与功能;最后给出信息一体化仓储物流系统网上平台的系统管理模块及用户操作模块的实现形式.     

Dominant CEO,Deviant Strategy,and Extreme Performance: The Moderating Role of a Powerful Board

This study examines the effect of dominant CEOs – defined as CEOs who are very powerful relative to other executives in their top management teams – on firm strategy and performance. Based on a sample of 51 publicly traded, single‐business firms from the US computer industry for the period 1997–2003, our results suggest that firms with dominant CEOs tend to have a strategy deviant from the industry central tendency and thus extreme performance – either big wins or big losses. Further, powerful boards weaken the tendency of dominant CEOs towards extremeness and, more important, improve the likelihood of dominant CEOs having big wins versus big losses. This study reconciles the pessimistic and heroic views regarding dominant CEOs, and suggests that the notion of power balance should be considered in a broader context.     

社会资本发展对企业财务的影响分析

社会资本理论于80年代晚期才引起理论界的广泛关注,此后又引入企业社会资本概念。社会资本的积累直接关系到企业的生存与发展,本文将社会资本理论应用于财务领域,从收益和风险两方面探讨了企业投资于社会资本应考虑的问题,为企业有目的地构建社会资本做初步分析。     

Vertical integration and innovative performance: The effects of external knowledge sourcing modes

We set out in this study to analyze the impact of vertical integration on the innovative performance of a firm and to explore the interaction between vertical integration and different modes of external knowledge sourcing. Our empirical results reveal an initial increase in the effect of vertical integration on innovative performance up to a certain level of integration, although this is subsequently followed by a decline; that is, the relationship is characterized by an inverted U-shape. The results further reveal that external knowledge sourcing is positively related to the innovative performance of a firm, albeit with a negative interaction with the level of vertical integration. In other words, firms with higher levels of vertical integration may be faced with barriers to the acquisition of external knowledge. Our findings suggest that firms should be cautious in their pursuit of a strategy of vertical integration, given the non-monotonic impact on innovative performance, whilst an increase in the level of vertical integration is also likely to diminish the effectiveness of the external knowledge sourcing.     

Forecasting the volatility of asset returns: The informational gains from option prices

A new class of forecasting models is proposed that extends the realized GARCH class of models through the inclusion of option prices to forecast the variance of asset returns. The VIX is used to approximate option prices, resulting in a set of cross-equation restrictions on the model’s parameters. The full model is characterized by a nonlinear system of three equations containing asset returns, the realized variance, and the VIX, with estimation of the parameters based on maximum likelihood methods. The forecasting properties of the new class of forecasting models, as well as a number of special cases, are investigated and applied to forecasting the daily S&P500 index realized variance using intra-day and daily data from September 2001 to November 2017. The forecasting results provide strong support for including the realized variance and the VIX to improve variance forecasts, with linear conditional variance models performing well for short-term one-day-ahead forecasts, whereas log-linear conditional variance models tend to perform better for intermediate five-day-ahead forecasts.