东北黑土保护性耕作技术的研究与实践

相对于世界其他黑土区由于犁耕、秸秆翻埋耕作而引起的土壤退化,我国东北黑土区以旋耕、秸秆离田、秸秆田间焚烧为主的常规耕作导致的土壤退化问题更为严峻。以秸秆覆盖还田少/免耕为核心的保护性耕作技术是黑土保护与利用最为重要的一种技术。文章简述了保护性耕作的由来、定义、国外成熟的技术模式及其在我国推广实施中存在的问题。总结了15年来以中国科学院为核心的科研团队,联合吉林省农业部门、高校、地方农业科学院等相关单位,攻克保护性耕作技术在东北黑土地实施的难关,研发高性能免耕播种机和条带耕作机,以及秸秆覆盖还田宽窄行免耕、条带耕作、垄作少耕等技术,总结形成东北黑土地保护性耕作的"梨树模式"并进行示范推广的历程。同时,对保护性耕作技术在我国东北地区广泛应用后的效果进行了展望。     

秸杆还田对耕地质量的影响

秸秆还田属于世界范围内普遍实施的一种增产方式,其不仅可以使农田增产,还能对农田的肥力增强,优化了对于秸秆的处理方式,将减少焚烧秸秆处理发生的可能性,通过焚烧这种方式对秸秆进行处理已经不能适应当今世界的环保发展要求,因此大部分的农业区域都会选择借助还田这种方式对秸秆进行处理,对农田耕地基本结构进行改良,使土质变得更加疏松,本文就这种处理秸秆的方式对耕地产生的影响进行分析。     

秸秆粉碎还田机械的技术分析

秸秆粉碎还田机械化技术是将摘除棒穗的秸秆,用机械直接粉碎撒于地面,然后,再用机械耙切深耕翻埋。采用秸秆粉碎还田机械化技术比传统的秸秆还田法省去割、捆、运、铡、沤、撤等多道工序。可大大提高工效,减轻劳动强度,而且还能把握农时季节,提高作业质量,增进肥效。     

玉米秸秆还田培肥地力研究综述

本文针对秸秆还田使用情况进行详细论述,而且将秸秆在还田培肥的作用做出研究。秸秆在还田以后不但能够将土壤中的养分提升,将土壤物理的性质做出恰当的改变,从而将生物活性有效的提升。秸秆在还田以后,相关的农作物都得到了较好的增产情况。除此之外,相关人员还应当对翻压数目、补氮所使用的数量等控制好,确保秸秆能够充分的粉碎。     

秸秆还田对土壤理化性质和玉米产量的影响

随着农业规模化、集约化水平的提高,我国秸秆年产量高达7. 6×109t,由此造成的环境污染问题日益凸显。秸秆作为物质、能量和养分的载体,是重要的有机肥料之一。因此,探寻一种既能实现秸秆资源化利用,又能降低生态风险的秸秆处理方式已经成为农业与环境领域的热点。本研究通过田间小区实验,探讨秸秆还田对土壤理化性质和玉米产量的影响。结果表明:秸秆还田使土壤有机质、速效氮、速效磷含量分别提高了10%、12. 1%和43. 8%;土壤速效钾含量变化不明显,在±0. 05mass%范围内波动;各处理土壤p H值略有升高,增幅为0. 06～0. 28个单位。同时,秸秆还田使玉米均高和产量分别提高了29. 2%和54. 6%,且土壤水分含量对秸秆还田的有效率影响较大。     

中国农村户用沼气主要发酵原料资源量的估算

农村户用沼气池运行的发酵原料主要有农作物秸秆、畜禽粪便和人粪尿,本文对这几种原料的资源量进行了估算,并分析了其分布状况。结果表明,1999年～2006年农作物秸秆的总量保持在（5.5～6.4）×10⁸t,以稻谷秸秆、玉米秸秆和小麦秸秆为主（约3/4）;畜禽粪便的总量从 33.9×10⁸t稳步增至41.2×10⁸t,畜类粪便中以牛粪（约46％）和猪粪（约35%）为主,禽类粪便（约3.0×10⁸t）中以鸡粪（约75%）为主;人粪尿总量随着农村人口变迁,从4.5×10⁸t减至4.0×10⁸t。3种类型中,以畜禽粪便为主,其比例从76%逐年上升至80%。河南、四川、山东、河北、湖南五省各种主要发酵原料的数量均位居前列,从其总量和比例关系来看,为发展沼气提供了充足和较均衡的原料,为大规模发展沼气提供了有利条件。     

集水农业技术地区适宜性评价

在实地调查基础上，依据集水农业技术的特点和要求，提出了集水农业技术评价指标体系，并且总结了河南省卫辉市集水农业技术体系实施中的五种模式，运用多目标综合评价方法对五种技术模式进行了综合评价，结果得出“山坡、道路、庭院集水和地膜覆盖集水区+水窖+低压管道滴灌+地膜覆盖冬小麦、玉米田免耕秸秆覆盖和玉米、麦田秸秆还田”技术模式效果最好，可认为是同类地区发展集水农业的最佳模式。     

论农作物秸秆还田综合利用技术的应用

农作物秸秆用途十分广泛,在饲料、肥料及综合利用等方面都有很大的价值。在秸秆还田中应注意技术要求,对秸秆还田机械要正确认识和使用,以提高经济效益。本文通过农作物秸秆还田的意义、作用、措施和机械化技术几个方面的阐述来表明农作物秸秆还田综合利用的影响。     

畜禽粪便生物质发电项目典型案例分析

以某项目为例,针对山东某区域禽畜粪便污染物开展了"厌氧消化技术-沼渣堆肥利用-沼气发电-余热回收利用"循环立体生态综合模式、良性循环为目标的新型生物质能源综合梯级利用体系建设。为畜禽粪便生物质发电技术在山东地区的推广提供了参数和依据。通过本项目的实施,可以将每万只鸭的粪便每年产生沼气约47000m~3,发电约3.4MW,节约煤约730kg,但要保障单位鸭粪沼气的产生量达到95m~3/t并且甲烷浓度达到50%。     

农户水稻秸秆还田技术采纳意愿及其驱动路径分析

水稻秸秆还田技术是政府主推的一项绿色农业技术,探讨农户对这一技术的采纳意愿及驱动路径,有助于农业可持续发展与生态文明建设的顺利推进。本文基于改进的MOA理论框架,根据湖北省3市农户问卷调查数据,利用SEM模型,分析了采纳动机、采纳机会、能力（抗风险能力、操作能力）、信任与农户水稻秸秆还田技术采纳意愿间的逻辑关系。研究发现：采纳动机对农户采纳意愿影响不显著,而采纳机会、操作能力、抗风险能力则对其具有显著正向影响,且整体效应分别为0.665、0.291、0.644,信任则具有间接效应,其大小为0.304。从跨组回归来看,随着家庭年收入的提高、受教育程度的提升,抗风险能力对农户采纳意愿的影响逐渐增强;随着家庭种植面积的扩大,采纳动机和抗风险能力对采纳意愿的影响更强。根据以上结论,本文提出了政府应该加快水稻秸秆还田技术推广进程、完善风险补偿制度、加大秸秆还田技术研发力度、加强政府信任建设以及建立以政府为主导的秸秆回收体系等政策建议,以便增进农户对水稻秸秆还田技术的采纳意愿。     

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.     

To serve and promote science development via innovation

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.     

Tracing the origin and early radiation of birds——Paleornithologist ZHOU Zhonghe

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."     

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.     

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.     

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.     

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.     

The Information Environment and Universal Service

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.     

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.