石林彝族传统药用植物资源及其保护利用

通过野外调查、走村串户,访彝医问彝民、标本采集和鉴定、结合资料收集进行研究。结果发现石林重要的彝族传统药用植物资源有91科176属196种(含变种),生活型特征以草本为主,有109种占55.9%,其余87种占44.1%;药用种子植物区系中,种/属比例为1.12,远远低于我国植物区系的8.5,种/科比例为2.21,科多种少,反映了该植物区系具有一定程度的古老性。     

北方园林彩叶植物抗寒性研究进展

低温是制约北方园林彩叶树种发展的重要因素。本文概略介绍了植物受冻害的机理、植物抗寒育种、生理生化指标在植物抗寒性研究中的作用、植物生长调节剂对植物抗寒的影响、彩叶植物抗寒生理等研究进展;提出了植物抗寒性研究的问题及对未来工作的展望。     

大兴安岭野生缬草的人工栽植技术

在对大兴安岭地区野生缬草资源全面调查的基础上,对北缬草(Valeriana fauriei)和黑水缬草(Valeriana anmmnsis)进行了人工栽培试验研究;阐述了从采种、种子处理、育苗及栽植管理等各环节的关键技术。     

Is it still economic to build a new coal-fired power plant in the U.S.? A real option analysis

In the U.S., virtually no new coal-fired power plants have been built in recent years. Both industry experts and academics seem to believe that no rational firm will build a new coal-fired plant. Will such a trend continue in the future? To provide insights into this question, we investigate the optimal decision of an electricity company with an irreversible and deferrable opportunity to build either a new coal-fired or natural gas-fired power plant as its new base-load resource. According to our real option analysis, the optimal decision depends on the location. In the case of the eastern U.S., it is optimal to choose a natural gas plant if a firm is given a choice among a new natural gas plant, a new coal plant and deferring the investment. However, contrary to the common sentiment in the industry and academia, building a new coal plant in the western U.S. is still more economical than building a new natural gas plant in the absence of emission pricing. Furthermore, introducing carbon pricing to western U.S. states, as California did, can substantially increase the probability that a firm will optimally choose a natural gas plant over a coal plant.     

空分装置运行常见故障与排除

本文介绍了空分装置运行过程中易出现的故障,分析故障产生的原因,并对故障提出了相应的解决方法和措施,对装置的日常运行提出针对性的建议,从而延长装置的运行周期,减少装置检修次数,为企业带来显著的效益。     

让自然参与设计：一种基于自然演替的 城市自生群落改良设计途径

城市自生群落具有重要的生态服务功能与潜力，但因其外貌不被公众所接受而难以在城市公共空间中应用。将群落生态学和设计学相结合，探索一种介入栽培植物对城市自生群落进行改良，最终形成具有一定美学价值的植物群落的途径。实验以植物群落设计美学原理和种间竞争原理为依据，向已经演替1年的城市自生群落中引入63种栽培植物，按照分层的方式对群落进行改良。3年的观测结果表明，有61.9%的栽培植物可以在城市自生群落中定居并建立优势，能对76.7%的自生植物起到抑制作用，使55.8%的自生植物消失。相比城市自生群落，改良后的群落美观度提高29.4%，公众接受度提高24%，群落的物种丰富度提高至2.29倍。相比一般的人工植物群落，改良后的群落可以节约58.2%的建植成本，降低83.9%的浇水成本和67.8%的除草成本。实验证明改良设计是一种可行的群落设计途径，能有效提高群落的物种丰富度和美学价值，同时让自然参与群落设计过程，实现人与自然的合作。     

Relationships between absenteeism,conservation group membership,and land management among family forest owners

Absentee landowners, or those who do not live on their forestland, own approximately 117 million acres of private forestland in the U.S. Thus, their land management decisions and activities influence the flow of forest-based goods and services. We explore the question of whether absentee family forest owners are less active land managers than resident landowners and whether membership in conservation organizations is associated with higher levels of land management activity by absentee owners. To examine these questions, we administered a mail survey to randomly-selected family forest landowners in Indiana. While we found some support for the contention that absentee owners are less active forestland managers than resident owners, we also found they are not necessarily inactive landowners. We found absentee owners were less likely to have: inspected their forestland for invasive plants, pulled or cut invasive plants, used herbicides to kill invasive plants, reduced fire hazard, or grazed livestock than resident owners. Absentee owners were more likely to be enrolled in the Indiana Classified Forest and Wildlands Program, a preferential forest property tax program. Absentee owners who are members of a conservation organization were more likely than absentee non-member owners to have undertaken a variety of land management activities, including: undertaking wildlife habitat improvement projects, inspecting their forestland for invasive plants, pulling or cutting invasive plants, enrolling in the Indiana Classified Forest and Wildlands program, and obtaining a management plan.     

关于电厂变压器的安装与调试分析

电厂要为用户输送分配电能离不开变压器的作用,电力系统能否稳定有效的工作与变压器的安全可靠性息息相关。变压器在电力系统中的作用多种多样,不管是变电所还是发电厂,都有不同规格、容量、电压级的变压器。电厂对变压器的安装调试和运作要严格根据相关的操作顺序和施工办法进行,不能够违背国家规定的安全准则和验收标准,这样才能保障变压器的安全可靠性。     

水电站厂房渗水原因分析及处理

文章介绍了纪村水电站厂房地面陆续出现向外渗水现象的具体情况,分析了造成这一现象的原因,提出了解决方法及防范措施。希望对水电站厂房的安全、稳定运行起到一定的借鉴作用。     

The Productivity Effects of Worker Mobility Between Heterogeneous Firms

We analyze the effect of worker inflows on establishments’ productivity, using German data. Previous studies for other countries have found positive effects of hiring workers from superior (more productive or higher paying) firms. Ranking establishments by their median wage, we find that inflows from inferior establishments seem to increase hiring establishments’ productivity. Further empirical analyses suggest our findings are due to a positive selection of such inflows from their sending establishments. These workers might have to find a better job match in order to advance their careers, an interpretation supported by the finding that the effect is driven by workers with short tenure at their previous employer. Our findings reflect the increasingly assortative pattern of worker mobility in Germany found in a related strand of literature.