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1.
利用昌都地区7个地面气象观测站具有30a（1980-2009年）的日照时数实测资料,分析了昌都地区日照时数年、季、月的变化趋势以及空间变化特征。 相似文献
2.
利用1962年～2012年嘉黎逐月日照时数资料,采用气候倾向率、M～K等方法,分析了近50年嘉黎日照时数的变化趋势、异常年份和突变特征。结果表明：近50年嘉黎年日照时数的线性趋势表现为显著的增加,平均每10年增加60．6h。四季日照时数都表现为增加趋势,增幅为8．92～18．62h／10a。但近30年四季日照时数均趋于减少,减幅为2．97～23．17h／10a,牟日照时数减幅达53．65h／10a。20世纪60至70年代季日照均偏少,80年代日照均偏多;90年代夏、秋季日照略偏少,春、冬2季偏多;进入21世纪前10年,秋季日照偏多,其他季节偏少。50年里,季、年日照时数在60年代多异常偏少年,异常偏多年仅出现在1982年。除夏季外,其他3个季节和年日照时数都发生了气候突变,季日照时数突变点均出现在70年代初;年日照指数突变较早,从1967年开始。 相似文献
3.
1960年至2009年河西走廊东部太阳辐射变化规律及太阳能资源利用分析 总被引：2，自引：0，他引：2
利用线性回归分析和Mann-Kendall检验法,统计分析了河西走廊东部1960年-2009年近50a来的太阳总辐射和日照时数的变化规律。结果表明:河西走廊东部年平均太阳总辐射为5988.7MJ/m2,为太阳能资源丰富区,太阳总辐射存在明显的季节变化,月和日太阳总辐射变化趋势均呈单峰型。河西走廊东部年平均太阳总辐射在波动中上升,其线性倾向率为+12.7MJ(/m2·a);春、夏、秋、冬季的太阳总辐射呈不同程度的上升趋势,线性倾向率为+4.72MJ(/m2·a)、+5.69MJ(/m2·a)、+2.0MJ(/m2·a)、+0.17MJ(/m2·a)。年太阳总辐射、年日照时数的突变增大年与区域内气候开始变暖年同步,气候变暖使区域内中北部川区降水呈增多趋势,说明全球增暖的气候背景下,降水增多对空中的大气污染物有抑制作用,有利于河西走廊东部太阳能总辐射值、日照时数的增大。河西走廊东部年日照时数在空间分布呈现由北向南逐渐减少,季节分布呈现由夏-春-秋-冬季减少。研究区域太阳能资源总量丰富,有利于太阳能资源的开发利用。 相似文献
4.
河流枯水极值分析与模型预测研究 总被引：1，自引：0，他引：1
以我国西南地区澜沧江流域干支流为例,对其枯水特征与径流补给,径流年内变化及其枯水分布做了概要的分析,同时对其河流枯水进行了模型应用研究。通过枯水最小月流量的试验以及显示的随机性,采用了软次模型,利用了11个测站,27a∽31a不等的序列数据,开展了枯水预测计算,其结果多年负轮长为2.13（a）,即小于最小月流量多年平均值。这表明其枯水出现的历时周期短,因此,在对该河流开发时应予以调控,统筹规划。由上可知,运用轮次算法对河流枯水的极值分析与预测是－经济实用的研究方法。 相似文献
5.
基于ERA-Interim再分析资料,采用通用热气候指数（Universal Thermal Climate Index,UTCI）,分析1979-2014年中国气候舒适度的空间格局和时空变化特征。结果显示：①中国除青藏高原地区外,年均UTCI呈纬向分布,由北向南增加;青藏高原地区呈“环岛状”分布。夏季“无热应力”覆盖面积最大,冬季最小;②“无热应力”频率最高值（> 70%）位于云贵高原南部,最低值（< 10%）位于青藏高原地区;极端冷应力在长江以北均有出现,内蒙古地区东部和东北北部（14%~32%）,及青藏高原大部（16%~40%）最为频繁;中国中东部和新疆盆地区域均有极端热应力出现,其中塔里木盆地东部频率在4%以上;③年均UTCI的趋势在中国东北部为正,西南部为负;最大的上升和下降趋势分别位于长江三角洲（（0.6~0.8）°C/10a和青藏高原西部（-0.8~0.6）°C/10a）。夏季UTCI在全国范围一致上升,冬季相反;④“无热应力”频率的趋势在中国北部为正,南部为负;上升和下降幅度最大的区域分别为青藏高原东部与黄土高原交界附近（（0.8~1.5）个百分点/10a~1.5个百分点/10a））和云贵高原南部（1.5个百分点/10a~2.8个百分点/10a）。极端冷、热应力频率在中国大部分地区均为增加趋势。 相似文献
6.
利用1957-2004年中国大陆740个代表站逐日降水资料,采用分离热带气旋（TC）降水的客观天气图方法（OSAT）从该降水资料中分离出影响华南地区的热带气旋降水（TCP）．采用气候趋势系数、小波变换和线性回归等统计方法对分离结果进行分析。结果表明：（1）近五十年来华南区TCP呈下降趋势,而且比全国下降趋势更显著。（2）TCP极值呈准12年的周期振荡,比华北区极值出现的时间提早2—4年,华南、华北两区TCP极值呈反位相关系。（3）增暖环境下华南区TCP的落区更趋于集中,TCP的周期比增暖前大2～5年,但TCP要比增暖前减少,且比华北区TCP减少出现的时间提早10余年。（4）TCP的变化与影响华南的热带气旋频数的变化密切相关． 相似文献
7.
基于均一性检验的1961年至2006年四川省日照变化规律研究 总被引：1，自引：0，他引：1
利用标准正态检验法(SNHT),对四川省117个站点1961年-2006年日照时数观测资料进行均一性检验,得到54个均一站点,并在此基础上通过统计方法初步分析了近46a四川省日照时数变化规律,得到以下几点初步认识:四川省88.9%的站点年日照时数呈减少趋势,且盆地减少幅度大于高原;各季日照时数变化以夏季呈减少趋势的站点范围最广、减幅最大,冬季次之,而春季表现为增加的站点范围最大;20世纪60年代、70年代日照时数偏多,80年代以来,日照时数持续偏少;有明显的突变现象,突变点在1980年附近;日照周期变化显著,"暗亮"交替现象明显,年代际及年际尺度的主要周期分别为24a、6a以及3a。 相似文献
8.
选取2002-2022年贵德县大天鹅（Cygnus cygnus）物候期资料，对物候期同期气温、降水、日照时数、风速四个气象要素进行分析。研究发现：近20年来大天鹅始见（鸣）期以8.2 d/10 a的速率逐年提前，绝见（鸣）期以2.3 d/10 a的速率逐年推迟。上年11月至当年3月的平均气温每升高1℃，大天鹅在贵德的绝见（鸣）期推迟1 d；上年11月至当年3月的降水量每增多10 mm，大天鹅的始见（鸣）期推迟4 d。表明迁徙鸟类物候期对环境气候因子变化敏感。 相似文献
9.
《青海科技》2021,(1)
根据海北地区4个地面气象观测站1965～2019年的日照时数资料,运用线性倾向估计、五年滑动平均、日照异常年、Mann-Kendall法、小波分析法和显著性检验等方法分析了海北地区的日照时数变化特征。结果表明:海北地区年日照时数变化总体呈振荡减少趋势,且减少的趋势相对明显,气候倾向率为-64.83h/10a,海北四县年平均日照时数刚察最多、门源最少。海北地区季日照时数总体呈下降趋势,其中春季、冬季的日照时数下降趋势不太显著,夏季和秋季日照时数下降趋势较显著。从气候倾向率来看,海北地区月日照时数都呈现减少趋势,日照时数最多的月份为5月,最少的月份为9月。根据天气、气候异常标准判断得出,年日照时数以异常偏少为主,主要出现在2018年和2019年。从小波变换得出海北地区日照时数存在着6a尺度和准13a尺度的周期振荡。 相似文献
10.
渭河流域上游干湿状况时空分布及其与地表水资源的关系 总被引：2，自引：2，他引：0
根据渭河上游渭源等11县（区）国家基本（一般）气象站1971年-2008年逐月气温、降水量、相对湿度、日照时数、风速等资料及渭河上游北道水文站1971年-2008年径流量资料,利用Penman-monteith（98版）公式计算了该区域的潜在蒸散量。建立了评价该地区干湿状况的干燥指数模型,对该区域气候、潜在蒸散量、干湿指数的变化特征及其干湿状况对地表水资源的影响进行了分析。结果表明,自1971年以来,渭河上游区域气温以0.3℃/10a的线性趋势上升;降水量呈较明显的周期变化;潜在蒸散以23mm/10a的线性趋势增加。干燥指数总体呈上升趋势,变化阶段性较强。1971年-1984年以0.826/10a的线性趋势降低,1984年-1997年以0.852/10a的线性趋势升高。渭河干流区域干燥指数较高,干燥指数较高的区域,正好与甘肃河东区域气候上的＂干舌＂相对应。1971年-2008年径流量以2567×104m3/10a的线性趋势减少。1984年-1997年径流量以9023×104m3/10a的线性趋势减少。干燥指数持续增大比较明显地影响了上游地表水资源,在一定程度上对下游水资源安全造成威胁。 相似文献
11.
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
12.
《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
13.
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
14.
《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
15.
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
16.
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
17.
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
18.
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
19.
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
20.
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