我国荒漠化土地为什么越治越多

从上世纪50年代算起，我们与沙漠化顽强搏斗了50多年，尽管局部地段取得了一定的成效，但残酷的现实是：沙漠化土地越来越多了。上世纪70年代，我国土地沙化扩展速度约为1560平方公里/年，目前则高达3436平方公里／年；全国荒漠化土地面积为2674万平方公里，占国土面积的27．9%。国家为治理土地沙漠化投入了大量的资金，相应启动了许多生态治理工程，为什么收效却不大呢？时值今年的世界荒漠化日，有必要对我国荒漠化防治的一些做法进行反思。     

青海湖湖岸形态变化及成因分析

青海湖在1975年～2000年的25年间,湖岸形态发生了较大变化,西岸和北岸陆地相对推进距离分别达到1 566.3m和3 266.9m,年平均推进距离分别为62.6m和130.6m;湖区东岸沙体形似"鸟嘴"侵蚀东岸湖水,近100 km2的水体被分离,只有很窄的河道连通湖区,且"鸟嘴"有继续延伸趋势.造成湖岸形态变化的主要原因是气候暖干化、湖水位下降、土地沙漠化和人类活动的共同影响.青海湖环湖地区气候暖干化导致的青海湖水位下降和土地沙漠化是造成湖岸变化的的直接成因;人类活动引起的草场退化则进一步加速了湖岸的变化.     

中国土地沙漠化的态势及其治理的基本模式

本文基于多年来研究沙漠及沙漠化的基础上,扼要介绍我国沙漠化现状、发展趋势及治理模式。土地荒漠化是世界上一个重要的生态环境问题,国际上对此极为关注,1977年联合国专门召开世界沙漠化会议,提出全球向沙漠化进军的行动纲领。我国沙漠及沙漠化土地面积约为153.3万平方公里,占国土面积的15.9%,其中,干旱区沙漠(戈壁)116.2万平方公里,干旱及半干旱区沙漠化土地面积约33.4万平方公里,湿润半湿润区风沙化土地面积约3.7万平方公里。中国土地沙漠化的趋势是局部改善,总体上仍在发展。70年代中期到80年代中期,沙漠化土地面积从17.6万平方公里增加到20.1万平方公里。当前治沙的重点应放在沙漠化土地上,特别是对那些正在发展的和已经开始沙漠化的土地,既要防止其发展,又要恢复土地的生产力。对于沙漠(戈壁)的治理,重点应放在位于其边缘的绿洲。除了采取措施保护现有绿洲、交通干线,工矿居民点等免受风沙危害外,还应进行综合开发、建立和扩大新绿洲。根据风沙化土地的特点与发展趋势,可以充分利用其周围地区丰富的劳动力和经济、技术发展的优势,进行全部开发。     

内蒙古沙漠化危险性分区评价与防治建议

内蒙古是全国沙漠化土地分布面积最广、沙漠化程度最严重的省区之一。据调查 ,内蒙古沙漠化土地有 41 65 .9万 hm2 ,约占全区总土地面积的35 .8%。其中沙漠和流动沙丘面积达 1 42 3.2万hm2 ,占全区沙漠化土地面积的 37.2 % ,轻度沙漠化土地面积有 1 2 0 1 .7hm2 ,占全区沙漠化土地面积的2 8.6%。内蒙古沙漠化土地分布广泛 ,在全区各旗县(市 )中除了乌海市、呼伦贝尔盟大部 ,以及土默特右旗、五原县、托克托县、科右前旗等 1 9个旗 (市 )的沙化率在 1 0 %以下外 ,全区其他旗县的土地沙漠化程度均较高 ,有些旗县 (市 )的沙化率甚至高达 89%。…     

为对抗世界沙漠化培养人才

沙漠化是当前世界上一个重要的环境问题.全球100多个国家有35%的陆地面积受到沙漠化的危害,引起了国际社会的震动和严重关注.1977年8月在内罗毕举行的联合国沙漠化会议上,通过了一项《向沙漠化进行战斗的行动计划》.同年12月第32届联合国大会上一致赞同这项行动纲领,号召世界各国为对抗世界沙漠化而斗争.1984年联合国第12届环境理事会举行特别会议,对7年来沙漠化的现状、趋势和治理情况进行了总评,指出沙漠化仍在继续蔓延,每年因沙漠化而丧失的土地有5—7万平方公里.直接引起的损失,不包括社会代价,每年约260亿美元.受其影响的人口,由1977年占全球人口的16%增加到20%.     

西藏沙漠化研究进展与未来防沙治沙思路

西藏土地沙漠化研究是我国荒漠化研究的重要领域,近30年西藏土地沙漠化研究取得了重要进展。文章摸清了西藏土地沙漠化现状、时空变化特征及其驱动因子,创立了包括高寒区沙漠化土地分类分级指标体系、地质-历史时期沙漠化演化过程、河谷风沙地貌特征等的西藏高原土地沙漠化研究理论体系,建立了高原特色的西藏土地沙漠化防治技术与对策,并基于西藏土地沙漠化现状、趋势及防治成效提出了未来西藏防沙治沙的思路和对策建议。     

草原沙漠化过程中的群落特征及四个共有种的抗氧化系统酶类的变化

文章探讨了在不同退化阶段(Ⅰ—冷蒿阶段;Ⅱ—褐沙蒿阶段;Ⅲ—虫实、刺穗藜阶段;Ⅳ—裸沙阶段)沙质草原的群落特征及四个共有种(羊草(Leymuschinensis)、糙隐子草(Cleitogenessquarrosa)、冷蒿(Artemisiafrigida)和扁蓿豆(Melilotoidesruthenica))的抗氧化系统酶类的变化规律,结果表明:沙漠化过程中不同阶段盖度的下降比例并不是均匀的,下降的比例是9.5%→63%→100%,下降比例越小,说明这一阶段越保守,从而也越稳定。抗氧化系统酶在四种植物中表现出不同的变化趋势:①扁蓿豆和冷蒿的SOD活性有上升的趋势,糙隐子草和羊草的SOD活性变化不明显;②扁蓿豆、糙隐子草、羊草的POD活性是急剧下降的,冷蒿的POD活性先下降后上升;③冷蒿、糙隐子草、羊草的CAT活性下降,扁蓿豆的CAT活性是上升的。     

低阶煤清洁高效梯级利用关键技术与示范

在世界能源结构中,煤炭一直处于重要地位。世界能源理事会《世界能源远景：2050年的能源构想》指出,到2050年,化石能源仍是最主要的能源形式,煤炭仍将发挥极其重要的作用。我国的能源形势尤为严峻,石油、天然气资源匮乏,煤炭储量相对丰富,煤炭在我国一次能源结构中占比近70%,居主导地位。随着核能、风能和太阳能等新能源的发展,煤炭的比例会逐步下降,但在未来相当长的时间内,其基础地位不会发生根本性改变。     

声音

正我国煤炭资源储量丰富,能源结构以煤炭为主。据统计,新中国成立以来,煤炭占我国一次能源生产量的70%、消费总量的60%以上。在我国一次能源中,煤炭是最经济和可清洁高效利用的能源。尽管近一两年来,煤炭占一次能源生产和消费量的比例略有下降,但在未来相当长一段时间内,煤炭仍将在我国能源结构中占较大比例,仍是我国的战略能源,是我国能源安全的"压舱石"。     

药物过敏 良药也可夺命

药物过敏,也叫药物变态反应,是人类最早观察到的过敏现象之一。近年来,随着医药事业的迅速发展,药物过敏现象与日俱增。20世纪30年代初期统计,我国药物过敏在一般人群中的发病率为0.5%,至50年代后期已增至2%,而到70年代中期在一般人群中药物过敏的发病率已达7.5%,1980年又增至7.92%。在将近半个世纪的时间内,药物过敏的发病率增长了15倍之多。据统计,常见可引起过敏反应的药物涉及18大类350多种,其中以抗生素引起的过敏反应最为多见,特别是各种类型的青霉素过敏反应危害极大,人群中对该类药物的过敏比例高达1%～10%,因药物过敏死亡的病例中约75%为青霉素所致。有专家预言,今后随着医药事业的进一步发展,大量合成新药的涌现,药物过敏现象将有继续增多的趋势。     

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.     

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.     

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     

Chinese Scientists Use Earth Observation Technologies to Study and Protect Wild Camels

<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     

More than Skin Deep – Understand Skin Biology by Means of Dermatogenomics

<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.