共查询到20条相似文献，搜索用时 406 毫秒
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刘晓敏 《内蒙古科技与经济》2020,(16)
利用新一代天气雷达和常规观测资料,针对2016年～2017年发生的短时强降水和冰雹天气中雷达回波参数、环境参数进行统计归纳,建立了这两种强对流天气的相应的参数指标。可以得出:发生短时强降水天气时的大气环境中不稳定能量的储蓄时间较长,对于环境参数的要求相较于冰雹天气要更加严格;而冰雹天气的雷达回波指标要比短时强降水天气的更加精细;对于选取的预报指标进行的回报检验中,预报准确率达73%;针对2018年7月15日～16日的暴雨天气过程进行指标检验,得出选取的预报指标能够应用于日常临近预报业务中。 相似文献
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杭州短时强降水特征分析及预报研究 总被引：8，自引：0，他引：8
利用杭州市近20年的1h雨量资料,分析了杭州短时强降水的发生规律,包括短时强降水的极值分布、年发生次数、月际分布、时段分布等气候特征。短时强降水雨量极值大多出现在台汛期间。杭州市短时强降水年发生次数的多年平均值为9.6次。杭州发生短时强降水的高峰期为7～8月。短时强降水容易发生在凌晨及午后两个时段。产生短时强降水的天气系统有:梅雨锋、西风带低槽、热带气旋、副高边缘西风急流、局地强对流系统等。本研究通过MM5模式产品得到各大气对流参数场及单点探空曲线,为预报短时强降水提供了新的思路。通过个例分析发现,在强对流天气发生前,各个大气对流参数场中心与短时强降水中心对应较好,杭州探空曲线反映了大气层结不稳定,有利于强对流天气发生。但是预报仅停留在定性和人工分析阶段,做出客观定量预报,并确定短时强降水的落区还有待进一步研究。 相似文献
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通过对南昌市的地质,尤其是水文地质资料分析,在此基础上建立研究区水文地质概念模型;并基于GMS软件建立研究区的地下水水流数值模型;经对模型识别和检验后,能够比较准确地模拟地下水系统。以该模型,对南昌市的三个应急水源地桃花、谢埠和尤口在应急开采条件下,进行三个月城市供水以及地下水在停采后的恢复模拟结果表明,可以作为城市供水的应急源地。 相似文献
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本系统的建立从短期预报实际业务需求和实际资料获取情况出发，利用提优子集和预报员经验合成而建立。从预报试验可以看出，在选好因子的前提下，用最了集在西藏单站预报是可行的，试报效果较好。通过经验选取预报因子，建立了集回归方程，选出全局最优子集回归建立短期单站降水预报模型，从而提供西藏地区各主要代表站（有探空资料五个站）6－9月客观逐日短期降水预报，这是一个尝试。对1999年6月进行试验应用，效果较好。 相似文献
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利用常规观测资料、雷达回波反演、自动站降水量等资料,选取发生在鄂东北地区暴雨过程的中尺度特征进行分析,总结预报暴雨天气的中尺度因子。从而为预报区域性强降水,确定降水落区提供依据。 相似文献
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《内蒙古科技与经济》2021,(14)
以2020年7月9日锡林浩特机场出现的冰雹天气和短时强降水天气过程为例,利用2020年7月9日MICAPS常规观测资料、锡林浩特机场的小时实况数据以及卫星云图、雷达资料进行分析,总结预报经验,凝练预报指标,以期为今后的预报事业做贡献。 相似文献
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在全球气候变化的背景下,持续暴雨、特大干旱等极端天气气候事件发生的频率和强度呈增加趋势,导致了更为严重的气象灾害。在气象防灾减灾形势日趋严峻和应对难度日趋增大形势下,开展10～30天延伸期预报技术方法研究,建立延伸期网上预报业务,是大势所趋。从大量观测资料中合理识别和提取影响区域极端天气的主要简化动力过程,基于新的近似动力学规律,构建带有较高预测能力的简单模型,成功提前10天以上预测2013年6-8月长江下游地区的3次主要的强降水过程。 相似文献
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A research group led by Prof. ZHAI Qiwei from the Institute for Nutritional Sciences under the CAS Shanghai Institutes for Biological Sciences has discovered that even relatively low doses of resveratrol-a chemical found in the skins of red grapes in red wine-can improve the sensitivity of mice to the hormone insulin according to a report in the October issue of Cell Metabolism.…… 《中国科学院院刊(英文版)》2008,22(1):14-15
Aresearch group led by Prof. ZHAI Qiwei from the Institute for Nutritional Sciences under the CAS Shanghai Institutes for Biological Sciences has discovered that even relatively low doses of resveratrol--a chemical found in the skins of red grapes and in red wine--can improve the sensitivity of mice to the hormone insulin, according to a report in the October,2007 issue of Cell Metabolism. As insulin resistance is often characterized as the most critical factor contributing to the development of Type 2 diabetes, the findings“provide a potential new therapeutic approach for preventing or treating” both conditions, the researchers said. 相似文献
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《中国科学院院刊(英文版)》2008,22(1):2-3
CAS should stick to the principle of rendering service to, and giving impetus for, the development of China＇s science enterprise by making S＆T innovations, said CAS President LU Yongxiang. The CAS president made the remarks in a recent talk to communicate the gist of the winter session of the Party＇s Leading-member Group at CAS, which was held from 7 to 11 January in Beijing. 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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《中国科学院院刊(英文版)》2008,22(1)
With great care, Dr. ZHOU Zhonghe takes out a package wrapped by cotton tissue from a drawer and says: "This is the gem of our collections: the fossil of a bird that lived 125 million years ago!" Then, pointing at a tiny mound, he explains: "Look, this is the claw and that is the head. It was in the egg shell and ready to hatch ... The species fell into a family of waterside inhabitants." 相似文献
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A joint study by Prof. ZHANG Zhibin from the CAS Institute of Zoology his co-workers from Norway US Swiss have indicated that historical outbreaks of migratory locusts in China were associated with cold spells suggesting that China's projected climate warming could decrease the pest's numbers. The study was published in Proceedings of the National Academy of Sciences on September .…… 《中国科学院院刊(英文版)》2008,22(1):6-7
Ajoint study by Prof. ZHANG Zhibin from the CAS Institute of Zoology and his co-workers from Norway, US and Swiss have indicated that historical outbreaks of migratory locusts in China were associated with cold spells, suggesting that China＇s projected climate warming could decrease the pest＇s numbers. The study was published in Proceedings of theNational Academy of Sciences on 17 September, 2007. 相似文献
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Caroline Haythornthwaite 《The Information Society》2001,17(3):211-226
A computer-mediated group is a complex entity whose members exchange many types of information via multiple means of communication in pursuit of goals specific to their environment. Over time, they coordinate technical features of media with locally enacted use to achieve a viable working arrangement. To explore this complex interaction, a case study is presented of the social networks of interactions and media use among members of a class of computer-supported distance learners. Results show how group structures associated with project teams dominated who communicated with whom, about what, and via which media over the term, and how media came to occupy their own communication niches: Webboard for diffuse class-wide communication; Internet Relay Chat more to named others but still for general communication across the class; and e-mail primarily for intrateam communication. Face-to-face interaction, occurring only during a short on-campus session, appears to have had a catalytic effect on social and emotional exchanges. Results suggest the need to structure exchanges to balance class-wide sharing of ideas with subgroup interactions that facilitate project completion, and to provide media that support these two modes of interaction. 相似文献
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Active biological molecules functional structures can be fabricated into a bio-mimetic system by using molecular assembly method. Such materials can be used for the drug delivery disease diagnosis therapy new nanodevice construction.…… 《中国科学院院刊(英文版)》2008,22(1):22-22
Active biological molecules and functional structures can be fabricated into a bio-mimetic system by using molecular assembly method. Such materials can be used for the drug delivery, disease diagnosis and therapy, and new nanodevice construction. 相似文献
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Electronic data interchange (EDI) provides means for interorganizational communication, creates network externalities, requires an advanced information technology (IT) infrastructure, and relies on standards. In the diffusion of such innovations, institutional involvement is imperative. Such institutions contain governmental agencies, national and global standardization organizations, local government, and nonprofit private organizations like industry associations. The last type of organizations we call intermediating institutions. They intermediate or coordinate ("inscribe") the activities of a group of would-be adopters. Unfortunately, little is known of how these organizations shape the EDI diffusion trajectory. In this article we examine one specific type of intermediating organizations?industry associations?and how they advanced the EDI diffusion process in the grocery sectors of Hong Kong, Denmark and Finland. We identify six institutional measures, placed into a matrix formed by the mode of involvement (influence vs. regulation) and the type of diffusion force (supply push vs. demand pull), that can be mobilized to further the EDI diffusion. Industry associations were found to be active users of all these measures to varying degrees. Their role was critical especially in knowledge building, knowledge deployment, and standard setting. Furthermore, institutional involvement varied due to policy and cultural contingencies and power dependencies. 相似文献
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Leah A. Lievrouw 《The Information Society》2000,16(2):155-159
This essay focuses on universal service and the Internet as means to support social and political participation. The emphasis on access to telecommunications systems in conventional approaches to universal service is contrasted with access to content. A model of the information environment is described that accounts for the roles of content and conduit, both of which are necessary conditions to achieve true access. A method is outlined for employing information indicators to observe or measure the information environment. 相似文献
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Puay Tang 《The Information Society》1998,14(1):19-31
The increasing prospects of digital piracy has prompted the perceived need by electronic publishers to adopt technical systems of protection, and governments to reform their copyright laws. This article is a preliminary study of the management of intellectual property by electronic publishers, defined as those involved in the production of online databases, and CD-ROMs. It focuses on three main issues: (1) how electronic publishers view the increasing threat of piracy; (2) the methods of protection employed to protect intellectual property in digital format; and (3) the importance of technological protection of intellectual property in electronic publications. The analysis is based on a sample of 23 UK electronic publishers. The interviews revealed an interesting assortment of protection methods and did not show that technological protection was a preferred way. Instead, the means of protection, in addition to copyright law, comprised niche markets, pricing, trust, bad publicity, and nontechnical and technical means. 相似文献