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1.
近50年来气候变化对西藏“一江两河”地区农业气候热量资源的影响 总被引：7，自引：0，他引：7
作物布局与种植结构是长期适应气候变化的结果。在全球气候变暖的背景下,农业气候资源相应发生变化,对区域农业生态系统必然产生一定的影响,因此分析区域农业气候热量资源的变化特征,为充分利用热量资源以及指导区域农业发展提供理论依据。西藏"一江两河"农区是西藏最重要的农作物集中分布区,农业气候资源的变化必然对该区作物和牧草的生长产生影响。本文基于"一江两河"地区主要站点的气象数据,采用平均气温、≥0℃和≥10℃初日、终日、持续日数和积温作为农业气候热量资源的指标,分析"一江两河"地区农业气候热量资源年际变化趋势及其热量资源变化在年内的分配。结果表明:①"一江两河"地区气温显著升高,增温以冬季最为明显;热量资源年际变化表现出显著的增加趋势;②研究区主要代表气象站点表现出≥0℃和≥10℃初日提前,终日推迟,持续日数延长的趋势;③从研究区各站点逐月积温年际变化来看,≥0℃积温在春季增幅明显,尤其以3月积温增加明显;≥10℃积温8-10月增加幅度较其他月份明显;④热量资源的增加正值作物或牧草生长始末期,热量的增加将影响作物或牧草的生长,如拉萨地区适宜冬小麦播种期明显推迟。 相似文献
2.
《内蒙古科技与经济》2021,(7)
利用1961年～2019年赤峰地区10个旗县区10个国家气象站逐日气温、降水量、日照时数等气象要素资料,统计分析了该地区近59年农业气候资源变化分布规律。结果表明,赤峰地区光能资源丰富,年太阳总辐射5 650MJ/m~2～5 830MJ/m~2,年日照时数2 800h～3 100h;热量资源充足,年≥10℃积温2 300℃～3 250℃,适宜发展农牧业;降水资源不足,年降水量330mm～460mm,并且变率较大,因此降水是限制赤峰地区农牧业发展的主要因子。 相似文献
3.
中国温带地区不同界限温度下农业热量资源的时空演变 总被引：3，自引：0，他引：3
《资源科学》2017,(11)
受全球气候变暖影响,农业生产面临较大风险,研究农业热量资源的时空演变对农业生态环境、作物布局和种植制度等具有重要意义。本研究利用中国温带地区及外延200km范围内840个气象站点1960—2015年逐日气温资料,采用气象插值软件ANUSPLIN空间插值,基于偏差法计算了格点尺度稳定通过不同界限温度(≥0℃、5℃、10℃、15℃和20℃)的起止日期、持续日数和积温,综合分析了气候变化背景下农业热量资源的时空格局及不同时段一年两熟制、冬小麦和春玉米可种植区的变化。结果表明:温带地区均呈现出初日提前、终日推迟、持续日数和积温增加的趋势,≥15℃的热量资源变幅最大;不同界限温度初日自南向北推迟,终日提前、持续日数和积温逐渐减小。起止日期和积温年代距平从1990年开始正负转变,1960—1980年与2000年以后差异显著;寒温带持续日数和积温低值区域减少、中温带和暖温带高值范围增大。时段Ⅱ(1990—2015年)温带地区一年两熟制、冬小麦和春玉米可种植区相比时段Ⅰ(1960—1989年)存在不同程度北扩。 相似文献
4.
汇水区是分布式水文地表积涝模拟的基本单元,汇水区划分的精确性对暴雨积涝模拟具有重要意义。利用水文分析工具进行研究区汇水区提取时,由于DEM栅格单元大小不同,汇水区划分空间分布精确性不同。为了研究DEM栅格单元大小对汇水区划分精度的影响规律,本文采用栅格单元大小为30、50、100 m DEM对同一地区进行汇水区划分计算,研究分析DEM栅格单元大小对汇水区划分涉及到的水流方向提取计算、汇流累积量计算、水流长度计算以及对流域分割计算的影响,从而实现DEM栅格单元大小对汇水区划分精度的影响评价。研究发现:栅格单元大小改变,对水流长度计算、流域分割、汇水区划分几个要素影响程度较大,栅格单元大小的变化对流向分析、汇水量提取几个要素的影响程度相对较小。栅格单元变大时,汇水区的面积减小,汇水区的个数也相应的减少;栅格单元变小时,汇水区的面积变大,汇水区的个数也相应增加。 相似文献
5.
6.
利用赤峰地区14个气象站1961年~2017年逐日气温、降水量资料,分析了气候因子时空变化特征及对农牧业生产的影响,结果表明:近57年来赤峰地区平均气温呈显著升高趋势(P0.05),升温速度0.23℃/10a;≥10℃活动积温呈显著升高趋势,57年升高了218.31℃;降水量呈微弱减少趋势,减少速率为0.16mm/a;热量资源显著增加,利于种植长生育期品种和二茬作物正常成熟,但降水量减少导致干旱发生概率变大,旱作农业遭受旱灾风险加大。 相似文献
7.
气候变暖对山东省农业的影响 总被引：16，自引：3，他引：16
选取山东省资料年代较长的86个地面测站1961年～2004年日平均气温、最高和最低资料，计算历年日平均气温≥0℃、≥10℃积温和<0℃负积温，以及无霜冻终、初日变化，深人研究山东省热量资源对气候变暖的响应及其对农业生产的影响。结果表明：1987年～2004年比1961年～1986年的平均气温明显增高，尤以最低气温增幅最大，这说明最低气温的变化比最高气温的变化更敏感，山东省气候变暖主要来自最低气温升高的贡献；冬季升温幅度大于夏季，日平均气温≥0℃、≥10℃积温增多，无霜冻终日提前、初日推后，无霜冻期天数增多，<0℃负积温绝对值明显减少。山东省20世纪80年代后期气候明显变暖，热量资源增加，对冬季大棚蔬菜等设施农业的生产有利，喜温作物面积扩大，复种指数提高；同时，干旱发生的机率加大，病虫等越冬存活率上升，防止难度加大。气候变暖对山东省农业影响是利弊并存。 相似文献
8.
气温数据栅格化的方法及其比较 总被引：31，自引：1，他引：31
用直接内插法、气温垂直递减法和多元回归方法分别对中国1961年592个气象站的气温数据进行栅格化，并用另外58个气象站相应的气温指标进行验证发现，直接内插法的计算结果与实测气温值在1月平均气温、7月平均气温和年平均气温3个指标上的相关系数分别为：0．95、0．78、和0．87，标准误差分别为3．4℃、3．6℃和3．3℃；气温垂直递减法的计算结果与实测气温值在3个指标上的相关系数分别为：0．98、0．97、和0．98，标准误差分别为2．4℃、1．1℃和1．3℃；多元回归方法的计算结果与实测气温值在3个指标上的相关系数分别为：0．98、0．97、和0．98，标准误差分别为2．3℃、1．1℃和1．4℃。因此，直接内插法的精度最低，不能用于大范围内的气温数据栅格化。气温垂直递减法和多元回归方法均具有较高的精度，尽管它们各有特点，但都可用于气温数据的栅格化。 相似文献
9.
基于GIS的贵州高原复杂地形下积温的精细空间分布 总被引：3，自引：1，他引：2
积温是研究作物生长发育对热量的要求和评价热量资源的一种指标。本文在前人研究的基础上,对原有的模型进行了一些改进,考虑了坡度、坡向和地形相互遮蔽作用对复杂地形下太阳总辐射的影响,基于数字高程模型(DEM)数据,研制了以海拔高度、复杂地形下太阳总辐射为参数的复杂地形下积温的分布式模型,在模型中还考虑了散射辐射的各向异性及坡地反射辐射对复杂地形下太阳总辐射的影响。应用100m×100m分辨率的DEM数据及气象站常规观测气象资料,计算了贵州高原复杂地形下100m×100m分辨率的≥0℃、≥10℃、≥15℃积温。结果表明:①局地地形因子如坡度、坡向、地形遮蔽等对积温的影响显著,使得复杂地形下积温的精细空间分布具有明显的地域分布特征,纬向分布特征不明显。地形对复杂地形下积温的影响是不容忽视的;②同一纬度,由于地形差异,积温的空间分布明显不同。阳坡、海拔较低处的积温偏高,阴坡、海拔较高处的积温偏低;③在缺乏复杂地形下坡面考察资料的情况下,建立以常规气象站观测资料为主的物理经验统计模型是实现细网格热量资源计算的可行途径。 相似文献
10.
本文论及的大别山、桐柏山地区,系指河南省境内淮河干流以南(长台关以上包括淮河干流两岸)的全部山地丘陵区,大致在北纬30°21′—32°40′,东径113°—116°之间,处于我国亚热带北部边缘。热量资源较暖温带丰富,比典型的亚热带稍有逊色。由于所处的地理位置特殊,地形复杂,热量条件区内差异甚大,为了因地制宜合理利用丰富的热量资源,最大限度地挖掘农业自然生产潜力,对本地区热量资源的特征、利用现状、存在问题及其合理利用途径进行分析探讨,具有重要的生产实践意义。 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