共查询到20条相似文献，搜索用时 203 毫秒
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引细入汤工程是利用引兰入汤工程将细河水引到汤河水库,其引水后,在平水年全汛期有75天通过引兰入汤工程溢流堰上过流,造成水资源浪费。通过观测数据统计及实验证明加高是可行的并且可以带来可观的经济效益,为此需加高引兰入汤工程溢流堰。 相似文献
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橡胶坝的坝高可调节,坝顶可溢流,起活动坝和溢流堰的作用,其运用条件与水闸相似,可用于防洪、灌溉、发电、供水、航运、挡潮、地下水回灌以及城市园林美化等工程中。 相似文献
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根据某水库工程特点,溢洪道的地形、地质条件对溢洪道的布置、溢流堰型式的选取、水力计算、结构计算、消能方式的选取及基础处理等方面进行了论述。 相似文献
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试验研究了在模拟平流沉淀池中,设置挡板、溢流堰对浊度去除效果的影响,以及在沉淀区中投放短管填料对浊度去除效果的提高。通过控制不同进水流态、短管填料不同投加方式、不同投放位置、不同投放量的对比,提出提高浊度去除率的最优方法。 相似文献
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微灌沉沙池是为了直接利用地表水资源作为微灌系统灌溉水源而提出的一种新型泥沙处理技术.项目研究建立了微灌沉沙池模型,对微灌用沉沙池进行了深入研究.在进水口加设调流墙、在溢流堰上沿水流方向设置溢流槽两个方面对传统沉沙池进行了改进,提出了较完整的新型沉沙池设计合理水力技术参数.对微灌沉沙池在生产实际中的应用研究表明,微灌沉沙池可以大大提高泥砂的沉淀效率,出池水流平均含砂量最大降幅可达95%,特别是对细颗粒泥沙的沉降具有很好的效果. 相似文献
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试验研究了在模拟平流沉淀池中，设置挡板、溢流堰对浊度去除效果的影响，以及在沉淀区中投放短管填料对浊度去除效果的提高。通过控制不同进水流态、短管填料不同投加方式、不同投放位置、不同投放量的对比，提出提高浊度去除率的最优方法。 相似文献
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Marjorie Armstrong-Stassen Margaret Landstrom Ramona Lumpkin 《The Information Society》1998,14(2):153-164
This study examined how students who had no prior experience with videoconferencing would react to the use of videoconferencing as an instructional medium. Students enrolled in seven different courses completed a questionnaire at the beginning of the semester and again at the end of the semester. Students at the origination and remote sites did not differ in their reactions toward videoconferencing but there was a significant difference for gender. Women reacted less favorably to videoconferencing. Compared to the beginning of the semester, students reported significantly less positive attitudes toward taking a course through videoconferencing at the end of the semester. There were no significant differences in students' attitudes toward videoconferencing across courses at the beginning of the semester but there were significant differences across the courses at the end of the semester. The results suggest the need for better preparation for both students and instructors. 相似文献
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披碱草属与大麦属系统关系的研究 总被引：1，自引：0，他引：1
卢宝荣 《中国科学院研究生院学报》1997,35(3):193-207
禾本科中，披碱草属Elymus L.为多倍体属，约含150余种；大麦属Hordeum L.具二倍体和多倍体，约有40余种，该两属均广泛地分布于全球温带地区。该两属，尤其是披碱草属的系统分类较为困难。基于形态学的传统研究认为这两个属的系统关系较远，而细胞学研究的资料却表明，披碱草属的H染色体组起源于大麦属。笔者对来源不同的披碱草属和大麦属的物种进行了远缘杂交，并对其属间杂种F1的减数分裂中期I染色体配对行为进行了分析。结果表明，若以披碱草属作母本，该两属有相对较高的杂交亲合力，通过对杂种幼胚进行分割和离体培养，也能获得杂种F1植株。属间杂种植株的形态介于双亲之间，但更接近于披碱草属，杂种的生殖器官发育不健全，而且所有的杂种F1均完全不育。细胞学的观察结果表明，这两个属间的杂种F1通常具有较低的减数分裂中期I染色体配对数，但有较大的变异。通过笔者的工作及掌握的形态学和细胞学的资料分析认为：披碱草属和大麦属的亲缘关系较为复杂，不能一概而论。含H染色体组的披碱草属和大麦属物种有着较近的亲缘关系，但这两个属中所含的H染色体组已产生了程度不同的分化；不含H染色体组的披碱草属及大麦属的物种具有较远的亲缘关系。 相似文献
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Benoît Godin 《Research Policy》2004,33(8):1217-1229
High technology is a concept much in vogue in OECD countries, for it is a symbol of an “advanced” economy. This paper looks at why and how the concept and its indicator acquired such fame. It explains that the reason has to do with the fact that the indicator emerged in the context of debates on the competitiveness of countries and their efforts to maintain or improve their positions in world trade. The first part looks at the early statistics behind the indicator (R&D/sales), statistics developed in official analyses of industrial R&D surveys before the 1950s. The second part traces the evolution of the R&D/sales ratio in the 1960s through its use as an indicator of research or technological intensity. The third part discusses the internationalization of the indicator via the OECD. 相似文献
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The effect of administration of N-acetylcysteine on ethanol and paracetamol induced hepatotoxicity was studied both biochemically
and histopathologically in experimental rats. The liver samples taken after twentyfour hours from the paracetamol administered
normal and alcoholic animals showed high degree of necrosis and related pathological changes. In the N-acetylcysteine treated
alcoholic rats and in the N-acetylcysteine pretreated paracetamol administered rats, the liver cells showed very little change
and appeared almost normal as evidenced by the histopathological studies. The activities of serum transaminases and phosphatases
were also high both in the alcohol treated and in the paracetamol administered animals. N-acetylcysteine treated animals partly
restored the serum transaminase and phosphatase activities, and the activities of the antiperoxidative enzymes. There was
also significant change in the serum and tissue lipid levels, and in the concentration of the tissue lipid peroxidation product-malondialdehyde
in both the alcohol treated and in the paracetamol administered groups. N-acetylcysteine treatment brought the serum and tissue
lipid levels, and the tissue malondialdehyde content towards normal. 相似文献
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本文基于中国制造业细分行业的数据对创新效率进行测算,实证考察行业中互联网的使用对创新效率的影响,并选取行业竞争程度作为门槛变量,以分析行业竞争程度如何影响互联网与创新效率的关系。研究发现：互联网的使用对创新效率具有促进作用,考虑到可能存在内生性问题,经过一系列稳健性检验后该结论依然成立。门槛效应检验结果显示：当行业竞争程度较强时,存在逃离竞争效应,即互联网对创新效率存在促进作用;随着竞争程度的减弱,促进作用也逐渐减弱;当竞争程度超过第二个门槛值时,即竞争程度较低时,这种促进作用转为抑制作用。研究结论对如何更有效地利用“互联网+”推动传统制造业转型升级具有重要现实意义。 相似文献
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This paper examines the category of "Woman" within the metastructure of a system of knowledge organization. We trace the subject scheme used to list books about women in a standard bibliographic guide over the first three-quarters of the twentieth century.Building on the feminist critique of subject representation, our analysis documents how the category was continually constructed over time, providing evidence of multiplication, isolation, and confusion in the process. The outcome is a framework that fails to capture the complex nature of knowledge about women and conceals relationships to the larger body of knowledge. The case of this legacy system exemplifies problems associated with representing the complexity and integration of knowledge and provides a basis for considering the potential residual impacts of current information organization and navigation systems. 相似文献
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以2010-2014年CNKI数据库收录的4 926篇国内应急管理研究文献为研究对象,运用文献计量学、内容分析法和CiteSpace可视化软件,对该领域文献分布、研究机构、学科跨度、内容结构和前沿热点等研究现状进行分析。结果表明,近五年国内应急管理研究处于稳定发展阶段,初步形成核心研究机构群,跨学科研究呈现出以公共领域为核心而多元学科领域高度综合化和融合研究的发展态势,研究内容的知识体系结构明显,并挖掘出该领域在"理论基础研究"、"应急管理体系建设"、"突发事件应对"、"应急资源保障"、以及"突发事件信息发布与网络舆情研究"等6个方面的前沿热点。 相似文献
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Milton Mueller 《The Information Society》2001,17(3):151-163
Long-standing conflict between domain name registrants and trademark holders prompted the Internet Corporation for Assigned Names and Numbers (ICANN) to create a global, mandatory arbitration procedure known as the Uniform Dispute Resolution Policy (UDRP). The UDRP has been used in 2166 cases involving 3938 domain names as of 1 November 2000. The policy gives the initiator of a complaint, generally a trademark holder, the right to choose which ICANN-accredited dispute resolution service provider (RSP) will handle the case. During the preparation of the UDRP,some feared that complainant selection would lead to "forum shopping" that might bias the results. This article performs a statistical assessment of the forum-shopping thesis and finds support for it. There are statistically significant differences in the various RSPs' propensity to take away names from defendants; there are also major differences in the number of cases brought to each RSP. RSPs who take away names have the larger share of cases. The study examines other variables that might explain differences in market share, such as price, the plaintiff's nationality, or the time taken to decide a case. It finds that nationality and time also are correlated with market share. The study concludes that shopping for a favorable outcome is an important factor in the UDRP. 相似文献
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浅谈教学管理工作中教学秘书的重要性 总被引：2，自引：0，他引：2
主要探讨了高校教学秘书工作的职责教学秘书的积极作用以及教学秘书应具备的素质,强调了教学秘书在高校教学管理工作中的重要性,同时建议各高校重视教学秘书队伍的建设,以提高教学管理水平。 相似文献