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[蝗灾!十分之一竹海被毁]黄脊竹蝗是竹子产区主要害虫之一,该虫每年发生一代,以卵在土中越冬。越冬卵于4月底5月初开始孵化,孵化期可延续到6月上旬。7月下旬为成虫期羽化盛期,8月下旬为产卵盛期,产卵可延续到10月初。大足、铜梁、永川等地为黄脊竹蝗的常发地。6月,有几天连睛高温,永川上百人到竹林区喷药灭黄脊竹蝗,“蝗尸遍野“效果不错 相似文献
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在鸟类繁殖季节,对银喉长尾山雀的繁殖和巢址选择进行了相关研究,研究表明：雀窝卵数在9-12枚之间,卵长径14．74±0．07mm,卵短径为11．33±0．05mm,卵重为0．96±0．02g,卵体积为0．97±0．01cm3;雀巢主要筑于黑桦（46．15％）和蒙古栎（30．77％）,另外,对巢树周围的生境有一定的偏好性,巢周树种多样性指数和均匀性指数分别在0．503～1．522和0．726～1．385范围内变动。 相似文献
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１ 研究区概况 研究区位于北纬３６～０ ２３～＇，东经９９～０５７＇，海拔２８８０ｍ，地处青海省共和盆地荒漠化地区，为青海省共和县沙珠玉乡。是青海省有名的“风库”，荒漠化面积占全区总面积的７６．５％。气候特征为干旱草原气候，年均降雨量２５０ｍｍ，年均蒸发量１７８２ｍｍ；年均温度２．５℃；年均风速３．９ｍ／s，年均大风日数 51ｄ，最多高达９７ｄ,年均沙尘暴日数２１ｄ，最多达５５ｄ。 研究区现有农田防护林带２７６ｋｍ，主要设置为青杨四行防护林带。主林带是与主风向垂直或成４５～０夹角的南北向林带（主风多为西… 相似文献
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早在人类开始计划生育的数千年前,许许多多的动物已经计划生育啦!生存环境决定计划生育人们常见的鸟类,每一种鸟在繁殖时每窝产几枚卵几乎是固定的。野鸡每窝要孵十几枚卵,连续十几天把这一窝要孵化的卵数产够了后,它就自动停止产卵,开始孵化。 相似文献
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徐冰 《大科技．科学之谜》2011,(6)
植物互助对付毛虫地处北欧的斯堪的纳维亚半岛森林茂密,郁郁葱葱。每年秋天,都会有铺天盖地的灰蛾涌向这里,并把卵产在桦树的树枝上;到了来年春天,孵化出的毛虫正好可以品 相似文献
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根据1970～1999年昌都冰雹的观测资料,分析了昌都冰雹的初、终日,日、月、年际变化,冰雹直径及持续时间.结果表明冰雹最早出现在3月27日,最晚出现在10月25日;冰雹集中出现在中午至傍晚;冰雹的月际变化呈双峰型;70年代降雹最多,80年代降雹最少,90年代又略有增多;最大冰雹直径15毫米,重量1克,平均雹径为4.2毫米;最长降雹持续时间为23分钟,降雹持续时间以5分钟内的出现频率最高. 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