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本文采用Bernaola-Galvan启发式分割算法对3种全球环流预报场预报风速序列以及气象站和测风塔的实测风速序列分别进行风速突变事件的挑选,并综合挑选结果对3种全球环流预报场对我国风速突变事件的预报能力进行检验和评估.结果显示: ECMWF全球环流预报场风速突变事件的预报效果最优,其次是GFS,然后为T639,但是在青藏高原和甘肃北部地区,GFS要优于ECMWF,在我国沿海尤其是南部沿海地区,T639为最佳;ECMWF在新疆北部、甘肃北部、内蒙古中西部、河北和山西风速突变预报准确率较高,约为30%以上,其次为东北、山东、河南和江苏,约为10%~30%,其余地区预报准确率基本上在20%以下,尤其在西藏和四川大部分地区预报准确率为0,T639预报场在沿海地区的预报准确率基本在30%左右;ECMWF预报场在我国大部分地区预报相位偏差在3h以内,幅度偏差基本上在3m/s之内,仅在新疆北部、甘肃北部、青海北部、内蒙古及辽宁地区相位偏差为3~6h之间,幅度偏差大于3m/s,在新疆北部和内蒙古东部幅度偏差达到6m/s. 相似文献
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利用2022年常规5 min间隔地面能见度观测资料、ECMWF及CMA-GFS模式资料,通过数理统计分析方法,对格尔木辖区内14个观测站的能见度观测资料与能见度模式预报数据进行检验分析,结果表明：（1）ECMWF模式较CMA-GFS模式能见度预报准确率稍高,ECMWF模式临近时次预报准确率较前一时次有略微提高,5 km准确率较3 km准确率高10%,总体上两种模式预报准确率均较差。（2）ECMWF模式预报值与观测值之间存在一定的线性关系,并且临近时次起报的预报值方程拟合度更高;ECMWF模式较CMA-GFS模式更接近观测值,但数值偏高,ECMWF模式的预报值存在20%左右的高估,而CMA-GFS模式存在70%左右的高估;ECMWF模式临近时次起报的预报场与观测值的离散程度更低,而CMA-GFS模式则相反。（3）从时空变化特性来看,两种模式的能见度预报值较观测值有数值偏大、时间滞后、落区偏南的特征。检验结果对提高当地能见度客观预报准确率具有重要的参考价值。 相似文献
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探讨老年人扩张型心肌病 ( DCM)的临床特征并与青年人 DCM进行比较 .通过临床观察对 80例老年人和 140例青年 DCM的临床资料进行对比分析 .结果发现 :( 1)老年组醛固酮值( 30 4 .8± 69.1)较青年组 ( 2 13.3± 54.5,pmol/ L)明显增高 ( P<0 .0 5) ,老年组 T3和 FT3值 ( 0 .78± 0 .2 1,2 .87± 0 .73)较青年组 ( 1.2 6± 0 .33nmol/ L ,3.55± 0 .64pmol/ L )明显降低 (均为 P<0 .0 1) ;( 2 )老年组室性心律失常发生率 ( 61.3% )较青年组 ( 92 .1% )低 ( P<0 .0 1) ;( 3)老年组低血钾、低血镁发生率高 (分别为 51.3%和 2 7.5% ) ,对洋地黄敏感性增加 ,易发生洋地黄中毒( 2 8.8% ) ;( 4 )老年组的病程 [( 11.0± 4 .7)年 ]和平均生存期 [( 6.9± 4 .2 )年 ]均较青年人 [( 5.2±2 .5)和 ( 3.4± 2 .7)年 ]长 (均为 P<0 .0 5) ;( 5)老年组的主要死因是充血性心力衰竭 ( 78.9% ) ,青年组则为恶性心律失常 ( 61.9% ) .结论为老年人 DCM的预后比青年人相对要好 ;老年人 DCM常伴低 T3综合征 ;心力衰竭、电解质失衡及交感神经兴奋是老年人 DCM室性心律失常的主要原因 相似文献
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基于2009年7月1日至2018年11月30日邢台市三级综合医院的脑卒中(脑梗塞、脑出血)住院患者的临床资料,结合同期13种气象要素,研究分析诱发脑卒中疾病的主要气象因素为气温、气压和风速。应用SPSS 25.0统计软件中Logistic回归方法建立分级预测预警模型,实际检验脑出血预报准确率达98.6%,脑梗塞预报准确率达99.2%,脑卒中预报准确率达95.3%。分级预警模型中脑梗塞、脑卒中发病人数大于或等于2人时预测准确率超过90%。此研究为邢台地区防治脑卒中疾病提供合理依据,为开展精细化医疗气象服务提供重要参考。 相似文献
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可用于城市空气污染预报的嵌套气象模式系统 总被引：1，自引：1，他引：1
基于区域大气模拟系统 ,采用网格嵌套方法 ,发展了由区域尺度气象模式 (R αM )和城市尺度气象模式 (C βM )组成的嵌套模式预报系统 ,为空气污染预报提供必需的气象要素场。共进行了 5组预报实验 ,并分别与对应区域和城市尺度的两类静力平衡预报模式 :Eta模式 (区域尺度 )和M βM (城市尺度 )的预报结果进行了比较研究。结果表明 ,R αM和C βM预报结果更能准确合理地反映天气系统的实际变化规律 ,其预报效果明显好于Eta模式和M βM。建立的嵌套模式预报系统可为空气污染业务预报提供一个好的工作平台 相似文献
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利用2016-2018年山西省太原地区夏季闪电定位监测资料和太原站探空数据,选取了对流有效位能、抬升指数、K指数、沙氏指数、700 hPa假相当位温、700～400 hPa平均相对湿度和总指数7个环境参数.分析了夏季各月白天和夜间闪电活动发生前各环境参数的特征及在不同取值范围内闪电过程出现的概率,确定各参数的预报指标.根据统计结果建立基于综合指标叠套法的太原地区闪电潜势预报模型,并将其应用于太原地区2019年夏季逐日闪电业务化预报.结果表明:(1)夏季各环境参数对闪电发生的指示阈值存在月差异,白天和夜间的差异更明显;(2)2019年逐日业务检验中白天准确率在75％以上,夜间准确率在80％以上,且有效降低闪电空报率,其中7月和8月的白天及各月夜间空报率均为0,说明该方法及闪电潜势预报模型对太原地区的闪电预报是可行的. 相似文献
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柴丽霞 《内蒙古科技与经济》2004,(22):63-63
1 包头市可利用供水水源状况包头市区可利用的供水水源有 :地下水资源、水库水和黄河水。包头市及近郊范围内的地下水多年平均补给资源量为 1 .2 6× 1 0 8m3/a;水库可向城市提供 5× 1 0 4 m3/d,作为城市自来水公司季节性调节水源 ;目前包头市在黄河昭君坟段和磴口段取黄河水量为 1 .5 7× 1 0 8m3/a作为城市供水 (包括包钢用水 )。综合地下水和地表水 ,现包间市区可利用的水资源量为 3× 1 0 8m3/a左右 (含 1× 1 0 8m3/a的农业用水 ,可作为城市供水资源量约为 2× 1 0 8m3/a左右 )。 1 996年城市总供水量为 2 .5 5× 1 0 8m3/a,地下水已… 相似文献
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通过对T213、NCEP、JMA和德国天气在线4种模式的产品对湖州从2005年1月到2007年6月的温度、降水预报的对比分析,利用前5日和历史权重法建立了对温度、降水的集合预报方法,检验表明:集成的温度、降水预报结果优于大多数模式单独的预报结果,降水24 h、48 h定性预报准确率70%左右.前5日集成模式重要温度预报的平均绝对误差在2℃左右,并且不存在明显的系统误差,预报达到了一定的精度;同时前5日的集成方法比历史集成方法更为优越,可提高温度和降水准确率5%左右,为预报员提供更精细的客观预报参考. 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