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统计分析呼和浩特机场2012-2017年雷暴观测资料,得出呼和浩特年雷暴平均日数为40.6d,初雷日期逐渐提早,最晚终雷日期逐渐退后,但年雷暴次数无明显变化趋势;分析了2017年9月22日的强雷暴天气的发展过程及各气象要素的变化,表明强雷暴过境时,地面风向风速、气温、气压等气象要素均会发生强烈变化,且它们的变化均与雷暴伴随的强降水及冰雹的开始停止及变化时间基本一致。 相似文献
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利用1981～2010年贡嘎气象站逐日气象观测资料,对拉萨贡嘎机场雷暴的时间分布特点和气候变化特征进行分析,结果表明:贡嘎机场雷暴日主要集中在5～9月,日变化呈两峰一谷的变化规律,最大峰值发生在夜间2时;夏季雷暴日数最多,秋季次之。近30年拉萨贡嘎机场年雷暴日数呈显著的减少趋势,为-5.3d/10a,主要表现在夏、秋两季。雷暴初日以-3.3d/10a的速度提早,终日平均每10年推迟4.2d。在10年际尺度变化上,20世纪80和90年代雷暴日数偏多,初日偏晚,终日结束得较早;21世纪初为少雷暴期,初雷来得早,终雷结束得晚。 相似文献
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哈尔滨机场雷暴气候特征统计分析 总被引：1，自引：0，他引：1
本文利用哈尔滨太平机场1996—2005年共十年的雷暴观测资料,通过统计分析,揭示出哈尔滨太平机场的雷暴气候变化特征。结果表明：哈尔滨机场雷暴具有明显的年、月、日变化特征：总体上呈逐年上升的趋势;雷暴最多年份出现在2003年,最少年份为1997年;雷暴主要出现在夏季,以7月份出现最多;一天中雷暴出现时间以午后至前半夜居多。雷暴日平均持续时间109分钟,多生于机场的偏西方向,消于偏东方向,多以伴雨弱雷暴为主．产生雷暴的天气形势主要以冷锋、暖锋、冷涡、空中槽形势为主。 相似文献
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通过对伊春5个气象站点历史雷暴资料的统计,结合其地理气候特点,分析小兴安岭地区雷暴的空间分布特征、月际、年际变化特征,结果表明,小兴安岭地区雷暴具有明显的局地和时效特征,地形地势是影响该地区雷暴的主要因子;南部地区雷暴日数明显多于中北部;春、夏、秋季是小兴安岭雷暴发生季节,主要出现在夏季,占全年雷暴总日数的76％;雷暴日数的年际差异比较显著,雷暴日数总体上呈减少趋势。 相似文献
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利用1961～2010年林芝逐年雷暴初日、终日、持续期和月雷暴日资料,分析了林芝近50年雷暴的气候特征,结果表明：林芝属于中雷暴区,年平均雷暴日数为29d,最多可达44d。夏季雷暴最多,冬季很少有雷暴。雷暴主要集中在4～10月,占全年雷暴日数的92.8%,以4月居多。雷暴主要出现在15~19时,占总雷暴次数的72.3%,其中16时出现最为频繁。雷暴平均初日为3月16日,平均终日为10月15日,平均持续期为214d,雷暴年频率为13.2%。20世纪80年代雷暴日数偏少,20世纪70年代最多,20世纪90年代和21世纪初正常。近半个世纪林芝年雷暴日数变化趋势不明显,说明该地年雷暴日数的随机性强。 相似文献
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本文介绍了得荣干、雨季分明,干季长,雨季短、冬无严寒、夏无酷暑、气温年变化小、日变化大,蒸发旺盛、日照充沛、降水稀少、气候特别干燥的基本气候特点,其中最显著的气候特征就是干旱,被称为“西南干旱中心”。同时还简单地分析了得荣干旱形成的主要原因。 相似文献
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对1996-2005年期间发生在新津机场雷暴天气的历史资料进行整理和特征分析,归纳出形成新津机场雷暴发生的几种天气形势主要有西南涡、副热带高压、冷锋、青藏高原上空低涡切变四种;把各类不同类型的雷暴进行了归类分析后,发现新津机场的雷暴天气有着普遍性的雷暴天气的特征,有时也呈现出独立的地方性特点,新津机场发生最多的是热力性雷暴;通过对各种雷暴天气预报的判断依据、包括温度场、能量场、稳定度等诊断工具进行地方性检验,总结出目前的各种不稳定度判断指标在新津机场雷暴预报的适用性,筛选出最适合新津机场天气特征的稳定度诊断工具为K指数,且温度场的诊断分析在预报春雷时有极大的指导意义。 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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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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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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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
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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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Prof. Raymond C.K. Chen a neuropsychologist with the CAS Institute of Psychology has made novel progress in his studies of schizophrenia. His work has been reported by a recent issue of Behavioural Neurology.…… 《中国科学院院刊(英文版)》2008,22(1):15-15
Prof. Raymond C.K. Chen, a neuropsychologist with the CAS Institute of Psychology, has made novel progress in his studies of schizophrenia. His work has been reported by a recent issue of Behavioural Neurology. 相似文献
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《中国科学院院刊(英文版)》2014,(3)
<正>In Xishuangbanna,one of China’s most biodiverse regions,landscape has changed dramatically during the past three decades due to the conversion of tropical rainforest to rubber plantations.In steep areas,terraces are often constructed before planting rubber trees,which causes two important changes in the soil:the destabilization of soil in the bench terraces and the increased vulnerability of unvegetated riser faces to erosion.Few studies have documented the nature and intensity of erosion on bench terraces.Prof.LIU Wenjie and his colleagues from the Xishuangbanna Tropical Botanical Garden(XTBG)conducted a study in Menglun County(21°5′39″N,101°15′55″E),Xishuangbanna to evaluate the influence 相似文献
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Chinese Scientists Use Earth Observation Technologies to Study and Protect Wild Camels 总被引：1，自引：0，他引：1
《中国科学院院刊(英文版)》2014,(3):267-268
<正>Chinese scientists plan to apply Earth Observation technologies to protect the critically endangered wild camels(Camelus ferus).With the help of remote sensing,satellite positioning,geographical information system and wireless sensors networks,they will be able to access the distribution and population of the wild camels and protect their habitats.The project will be carried out by the International Research Center for Wild Camel Conservation,which was jointly established earlier this year by the Institute of Remote Sensing and Digital Earth(RADI)of the Chinese 相似文献
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WANG Sijia 《中国科学院院刊(英文版)》2014,(2):192-194
<正>The Paul Gerson Unna Research Group on Dermatogenomics was founded in October 2012 at the Partner Institute for Computational Biology.The ultimate goal of the group is to understand the biology of skin and skin appendages. 相似文献