基于MapX的列车调度监控系统电子地图实现

利用MapX组件式产品提供的基本地理信息操作功能,运用GIS(地理信息系统)显示设计,以及信息查询、轨迹回放等主要功能,在基于移动卫星通讯的铁路调度监控系统中,实现铁路调度监控功能,具有简单、方便、实时、高效等优点,同时也指出了有待改进和提高的方面。     

中国农民高龄化原因探讨

城市工业文明对年轻人具有极大的吸引力,有利于中国的工业化和城镇化,有利于大幅度减少农村人口,但对中国农业劳动力的接替也产生了较大影响。农产品低价格的现状难以保证农民生产利益,从事农业劳动得不到较高的收入,这将直接威胁到中国农业劳动主体的接续,将对农业发展起到严重的阻碍作用。社会保障滞后迫使农村人口离开农村,大批的而不是个别的年轻人不再留在农村务农。缺乏政府对于农业的有力扶持,即扶持并没有达到现代农业建设的高度,这是致使目前种地的农民已经出现明显高龄化的政策性原因。     

Do Analysts Matter for Corporate Tax Planning? Evidence from a Natural Experiment

We exploit an exogenous shock to analyst coverage as a result of brokerage house mergers and closures to examine whether financial analysts influence the tax‐planning activities of the firms they cover. Using a difference‐in‐differences design, we find that, on average, firms affected by broker mergers and/or closures experience a reduction in their GAAP (cash) effective tax rates (ETR) of 2.5 percent (2.6 percent), relative to control firms, translating into average tax expense (cash tax) savings of $34 ($35) million. The treatment effect is more pronounced among firms with lower pre‐event analyst coverage. To explore how analysts affect tax planning, we further document that the treatment effect is greater among firms that lose an analyst who provided an implied ETR forecast in the past, suggesting that analysts influence tax planning via their tax‐specific research efforts. In addition, we find that after merger/closure, weakly governed firms increase their use of aggressive tax strategies, and financially distressed firms experience a larger reduction of cash effective tax rates, relative to control firms. Overall, we provide evidence that a shock to analyst coverage sufficiently changes the cost‐benefit trade‐off of tax planning.     

Why do stock repurchases change over time?

Recent studies have shown the time trends of firm stock repurchase behavior. We examine these time changes for stock repurchase through the lens of real activities earnings management. Managers appear more likely to manipulate earnings through stock repurchases since the passage of the Sarbanes–Oxley Act (SOX) in 2002. Furthermore, suspect firms that just missed analyst earnings per share forecasts have higher incentives to manipulate earnings through stock repurchases. The results are not driven by changes in corporate governance associated with the passage of SOX. Overall, our results suggest earnings management can be a significant determinant of the dynamics of stock repurchases.     

天津都市农业科技发展战略研究

本文在天津都市农业科技发展现状分析基础上,研究未来发展面临的重大战略问题,提出未来15年天津都市农业科技发展的战略需求、思路、任务和措施。     

粉煤灰合成4(A)沸石最佳工艺条件的研究

研究了利用粉煤灰合成4A沸石的工艺过程，通过正交试验考察了钠铝摩尔比、硅铝摩尔比、水钠摩尔比、晶化温度和晶化时间不同条件的变化对所合成样品钙交换能力的影响，选定了最佳工艺条件，合成的样品具有良好的钙离子交换能力和结晶度。     

抗肿瘤药在中国的使用现状

综述了抗肿瘤药物在中国的使用现状及发展情况.