水稻与全球变暖

目前,除去工业、汽车排放等人类活动,全球主要温室气体约有30％来源于农业.温室气体包括甲烷、二氧化碳、氧化亚氮等,这些气体进入大气后会导致气候变暖,从而造成灾害频发.甲烷是位于二氧化碳之后的第二大温室气体,对全球温室效应的贡献率为20％,其中稻田排放的甲烷约占人为甲烷排放总量的11％.另外,稻田还是氧化亚氮的主要排放源之一,氧化亚氮是第三大温室气体,对全球温室效应的贡献率为6％ ～ 8％.这些数据表明,水稻或多或少与气候变暖有关,但是以水稻产生的温室气体分量来看,又未必是导致全球变暖的主要原因.     

稻田温室气体排放的时空差异性与精准施肥

文中试图以不同施氮处理下稻田温室气体排放的时空差异性为依据 ,为精准施肥提供环境方面的信息。通过实验观测 ,研究了不同施氮处理条件下 ,稻田温室气体CH4和N2 O日排放的差异性。施氮量不同的小区 ,CH4排放强度有很大差异 ,最大差值为 1 5 8mg·m- 2 h- 1 ,CH4排放强度随着施氮量的增加而减少 (R =0 88)。甲烷排放的日变化幅度也较大 ,在 1～ 6 6倍左右。在不同施氮水平下 ,N2 O则随着施氮量的增加 ,排放通量逐渐减少。如果以观测的温室气体排放强度变化为基础 ,同时考虑粮食产量的变化规律 ,施氮量为 2 70kg·hm- 2 时 ,温室气体排放量较低。实际上 ,精准施肥需要考虑诸多因素如土壤的理化性质、水稻不同生长季节的养分需求等等     

中国稻田温室气体的排放与减排

中国是世界上最大的水稻生产国, 水稻种植面积占全球总种植面积的30%。水稻生产在粮食安全方面起着重要的作用, 稻田却是温室气体甲烷(CH₄)和氧化亚氮(N₂O)的重要排放源。文章综述了稻田CH₄和N₂O的产生过程、影响因素及时空变异规律, 总结了近年来我国稻田CH₄和N₂O排放总量的估算结果, 并提出了针对性的温室气体减排措施。     

中国南方旱田转水田后温室气体减排年限预测

农业生产活动是大气温室气体的主要来源之一,不同作物栽培体系和管理方式都会影响农田温室气体的排放。国内外已有大量关于农业温室气体排放规律和控制机理的研究,但关于土地利用方式转变对温室气体排放规律和影响机制的研究相对较少。本文以中科院千烟洲红壤丘陵综合开发试验站为研究平台,通过对新（刚从旱田转为稻田）老（过去20余年一直为稻田）稻田进行连续4年（2013—2016）观测,分析稻田温室气体排放规律及影响因子。在此基础上预测稻田温室气体排放量的动态变化。研究表明,旱田转变为稻田后,前4年新稻田CH₄排放通量显著低于老稻田,但随着耕作年限的延长新稻田的CH₄排放速率呈增加趋势,而老稻田的CH₄排放速率没有明显变化趋势;耕作年限对CO₂和N₂O的排放速率影响不显著;新稻田的pH值和土壤有机碳含量低于老稻田。模型模拟结果表明缩短稻田轮作（水-旱轮作）期（小于7年）能够有效降低稻田CH₄和总温室气体排放量。该结果表明利用老稻田的CH₄排放系数可能会显著高估新稻田的CH₄排放量。研究结论可为准确评估土地利用方式变化对农业温室气体排放的影响提供新的视角,同时为区域农业温室气体管理和减排政策的制定提供科学依据。     

典型大嵩江流域稻田CH_4和N_2O排放的分析与控制研究

如何在保证水稻产量的同时减少稻田温室气体排放一直是学术界关注的重要问题。本研究在宁波市大嵩江流域内选取了12块稻田样地,在采集研究样地土壤特性和管理方式数据的基础上,使用DNDC(DeNitrification-DeComposition)模型模拟估算了不同管理模式下样地的水稻产量及其对应的温室气体CH_4(甲烷)和N_2O(氧化亚氮)排放量。结果表明,CH_4的排放量和稻田的淹水深度以及N_2O的排放量和N肥(尿素)的施用量之间均存在明显的相关关系——通过优化管理方式可以在保持水稻产量的同时实现温室气体减排。具体方式有:改变稻田淹水天数,选取高产低排稻种,控制N肥使用量和减少秸秆还田,然而其效果则又与土壤特性有很大的关系。     

闽江河口大小潮日孔隙水甲烷浓度与排放通量关系研究

选择闽江河口最大的鳝鱼滩湿地为研究对象,分别在2010年4月（小潮月）与10月（大潮月）的大潮日（2010年4月14—15日和9月9—10日）和小潮日进行观测。取样并测定了闽江河口鳝鱼滩湿地的中高潮滩过渡区短叶茳芏与芦苇混生群落沼泽湿地孔隙水中甲烷浓度与湿地甲烷排放通量。结果表明：4月小潮日甲烷排放通量与孔隙水甲烷浓度负相关（R=-0．393）,相关性不显著（P=0．052〉0．05）;4月大潮El两者正相关（R=0．118）,相关性不显著（P=0．622〉0．05）。9月小潮日两者正相关（R=0．613）,相关性极显著（P=0．002〈0．01）;9月大潮日两者正相关（R=0．509）,相关性显著（p=0．037〈0．05）。     

体外法测定青藏高原冬季草场放牧牦牛甲烷排放量

牦牛甲烷排放量试验采用体外产气法对冬季牧场放牧牦牛甲烷排放进行了初步研究。采集冬季牧场主要的可食牧草早熟禾（Poaannua）、中华扁穗草（Blysmussinocompressus）、獐牙菜（Swertiabimaculata）作为培养底物,并选择3头大通牦牛（1ive—weight：170±5kg）,通过瘤胃采样器采集瘤胃液进行体外培养,36h后终止发酵。结果表明,随着培养的增加,体外产气量也逐渐上升,在24h达到最大值。早熟禾、中华扁穗草、獐牙菜24h累计产气量分别为129．2mL、70．8mL和73．8mL。而甲烷产量在0—6h逐渐升高,在9h达到最大,早熟禾为31．10L／Kg和獐牙菜18．74L／Kg,之后随培养时间的增加而逐渐降低。在牦牛采食上述三种牧草的情况下,其一天产甲烷量在18．74L／kg-31．10L／kg之间。     

自然湿地甲烷排放时空变化规律研究（英文）

对三江平原沼泽湿地甲烷排放时空变化规律及其影响因素进行了研究。自然湿地甲烷排放存在着明显的季节性变化，即随着植物生长甲烷排放量不断增加，在8月未达到最大值，而后下降。这一变化特点主要受温度和沼泽静水层深度所控制。春季低温不仅直接降低了甲烷的产生强度，而且也降低了其它好氧微生物的活性，使得沼泽水中存留较多的氧气，这些氧气直接加速了沼泽水中甲烷氧化，同时又提高了沼泽水的氧化还原电位，后者反过来进一步减缓甲烷的产生。三江平原不同植被生长的沼泽甲烷排放通量呈如下特点：毛果苔草>乌拉苔草>小叶章。莎草科植物生长的沼泽中，72-86%的甲烷通过植物排放进入大气，而小叶章生长的沼泽只有28-31%。毛果苔草促进了沼泽水中甲烷的氧化而不是产生，相反小叶章通过释放根系分泌物刺激甲烷产生的能力大于分泌氧气促进甲烷氧化的能力。毛果苔草沼泽水中更高的甲烷浓度是由于深的静水层淹没更多的植物立枯，从而为产甲烷菌提供充足的底物所致。     

丘陵山区覆膜旱作稻田土壤硝态氮和铵态氮动态变化规律探讨

采用田间长期定位试验对丘陵山区连续4年覆膜旱作、裸地旱作和常规水作条件下稻田土壤硝态氮和铵态氮的动态变化规律作了研究。结果表明,覆膜旱作稻田土壤的铵态氮和硝态氮显著高于常规水作。土壤NO^- 3-N占无机氮的81．16％～90．46％,是土壤铵态氮的4．32-9．49倍。因此,丘陵山区覆膜旱作稻田土壤矿质氮主要以硝态氮为主。     

施肥对长江中下游稻田温室气体排放的影响——基于Meta分析

气候变暖已成为全球关注的热点话题,农业温室气体是气候暖化的重要排放源。目前许多学者研究了不同施肥措施下温室气体排放的特征,但实验结果之间存在一定的差异。为了综合评价区域内不同施肥措施(单施无机氮(N)、无机氮磷钾(NPK)和有机无机配施(OF))下土壤温室气体排放的特征及其净减排潜力,本文基于长江中下游地区40篇关于施肥对稻田温室气体CH_4和N_2O排放的文献,筛选出339组样本数据,采用Meta分析方法从施肥类型、施肥时间和施肥水平三个方面定量研究了3种施肥措施对稻田CH_4和N_2O排放的影响,并在前期研究的基础上,估算了各个施肥处理下的综合增温潜势、净增温潜势以及温室气体排放强度。结果表明:N、NPK和OF处理下CH_4周年排放的效应值分别为0.24、0.27和0.63,N_2O周年排放的效应值分别为1.25、1.26和1.41。随着施肥次数的增加,N、NPK和OF处理下温室气体排放的效应值均逐渐增大;随着施肥量的增加,N处理表现为增加的趋势,NPK处理表现为减少的趋势,OF处理表现为先增后减的趋势。对于3种施肥处理下的净增温潜势大小为OFNPKN,其中CH_4排放对温室气体的贡献最大;3种施肥处理下的温室气体排放强度大小为OFNPKN。从粮食增产和温室气体减排两方面综合考虑,施用氮磷钾(NPK)是长江中下游地区稻田较适宜的施肥方式。     

Students' Reactions to the Introduction of Videoconferencing for Classroom Instruction

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.     

Cooler temperatures inductive to locust outbreaks

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.     

Exploring Multiplexity: Social Network Structures in a Computer-Supported Distance Learning Class

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.     

Low doses of a red wine ingredient figh diabetes in mice

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.     

The Role of Intermediating Institutions in the Diffusion of Electronic Data Interchange (EDI): How Industry Associations Intervened in Denmark, Finland, and Hong Kong

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.     

How Electronic Publishers are Protecting Against Piracy: Doubts About Technical Systems of Protection

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.     

Rough Justice: A Statistical Assessment of ICANN's Uniform Dispute Resolution Policy

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.     

Prevalence of soft neurological signs in Chinese people

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.     

Molecular motor assembly of a biomimetic system

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.     

Monoculture Rubber Plantations Have Negative Ef ects on Controlling Splash Erosion

<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