高效液相色谱-串联质谱法检测蔬菜水果中65种农药残留方法研究

建立了一种高效液相色谱-串联质谱法（LC／MS／MS）同时测定蔬菜、水果中65种农药多残留的方法,并应用于样品中农药残留的定性定量检测。样品以乙腈提取,经石墨碳／氨基串联柱固相萃取,采用C18柱分离．以含0．02％甲酸乙腈-0．02％甲酸水溶液为流动相梯度洗脱,多反应监测（MRM）模式下,以保留时间和质荷比对分离出的组分予以定性确证,外标法峰面积定量。65种农药在一定的范围内线性关系良好（r〉0．995）．样品中最低检出浓度为0．02～20μg／kg,样品的平均加标回收率为70％～120％。方法简便、快速、灵敏,适用于蔬菜、水果中这65种农药的残留分析。     

植物油中农药残留分析的研究现状与发展趋势

植物油中农药的残留严重威胁到人体的健康,所以农药残留分析检测技术尤为重要。文章综述了国内外常用的农药残留提取和测定方法,包括:固相萃取、固相微萃取、超临界流体萃取法、基质固相分散萃取法、微波辅助萃取等提取技术及气相色谱法、液相色谱法、液相色谱-质谱联用法和气相色谱-质谱联用法等检测技术。文章评述了这些方法的优点与缺陷,并提出了食用植物油中农药残留检测方法的发展趋势。     

气相色谱法测定茶叶中有机磷农药残留量的研究

建立了利用固相萃取气相色谱法分析茶叶中11种有机磷农药残留量的方法。样品首先经二氯甲烷和正己烷的混合溶剂提取,然后经SPE小柱固相萃取净化,采用气相色谱测定。实验结构表明,11种有机磷农药均能在CP-sil8（15m0.53,1.5um）毛细管柱上得到很好的分离,符合农药残留量检测的要求。该方法具有称样量小、试剂用量少、操作简化的优点,为检测茶叶中有机磷农药残留量的研究提供了科学的方法。     

西藏大蒜干粉中大蒜素的提取与测定

本实验对西藏大蒜晒制干粉提取大蒜素进行了三种常规提取和超临界提取的比较实验,并对未经提取的大蒜干粉、提取物、超临界CO2提取剩余干粉进行了大蒜素的含量检测.结果表明:(1)大蒜晒制干粉中每克干粉含活性成分(含硫化合物)0.0341g,超临界CO2萃取后的大蒜干粉中每克干粉含大蒜素为0.77g,超临界CO2萃取的效率理论值为77.6%,(2)超临界CO2萃取实验中实际得到的大蒜素远低于理论值,只有0.0012g每克大蒜干粉,其原因可能是超临界系统容积大损耗大;(3)通过水煮-有机溶剂萃取法、有机溶剂浸泡提取法以及乙醇浸泡提取法三个实验的比较,表明,无论在大蒜油得率、大蒜素纯度以及大蒜素含量方面,水煮-有机溶剂萃取法均比其他两种方法有优势,乙醇浸泡提取法大蒜粗提物多,杂质含量也很最高.     

原花青素分离、纯化现状及发展趋势展望

花青素是一种具有重要生理活性的多酚类化合物。本文综述了天然原花青素的提取方法,其中包括有机溶剂提取、微波提取、超声波提取、超临界CO2萃取以及酶法等,以期为开发利用原花青素提供依据。     

青稞麸皮油GC-MS分析及青稞麸皮β-葡聚糖含量测定

对青稞麸皮(样品B)进行二氧化碳超临界萃取物进行GC-MS分析,对两种形态的青稞麸皮分别进行粉碎,水浴提取,超声波提取等处理后采用刚果红法对青稞麸皮中β-葡聚糖含量测定,青稞麸皮含油量为5.73%,青稞麸皮油具有丰富的不饱和脂肪酸,超临界萃取后青稞麸皮β-葡聚糖含量很高,萃取后样品沸水浴处理后其β-葡聚糖含量分别为样品A:15.23%和样品B:14.79%。β-葡聚糖提取方法沸水浴优于超声波处理,超临界萃取脱脂有利于β-葡聚糖提取。     

烟用香精香料的品质分析

文章分别采用溶剂萃取、同时蒸馏萃取、固相微萃取和水蒸气蒸馏等4种方法提取烟用香精B3 样品中的挥发性和半挥发性风味成分,并采用信息量和重现性两个指标考察最优提取方案.     

微波辅助萃取技术在天然产物活性成分提取中的研究

文章综述了微波辅助萃取技术在天然产物活性成分提取中的应用,重点介绍了在天然产物中提取黄酮类、多糖、苷类三种活性成分,最后指出微波辅助萃取技术已成为当前和今后新型提取技术研究的热点之一.     

关于乙虫腈及其代谢物残留量在水稻及其环境中检测分析的研究

本文采用加速溶剂萃取(ASE)提取,固相萃取(SPE)小柱净化,气相色谱分离测定,分析了水稻、水体及土壤中乙虫腈及其代谢产物的残留状况,取得较好结果。可以通过该方法实现对环境及稻谷作物污染情况跟踪监测,进行乙虫腈及其代谢产物在稻田中的残留消减动态研究,实现对受污染水土粮食作物的风险预判。     

气相色谱法法测定蔬菜、水果中的多种有机磷农药残留量

目的:建立用气相色谱法测定蔬菜、水果中7种有机磷农药残留量的方法。方法:蔬菜、水果中的残留有机磷经过乙腈提取,提取溶液经过滤、浓缩后,用丙酮定容,采用岛津GC-2010型气相色谱仪(FPD检测器),自动进样,Rtx-1毛细管色谱柱,以保留时间定性,外标法定量。结果:仪器的最小检测量满足国标要求,最低检出浓度为0.01-0.03 mg/kg,样品的加标回收率为70.0%~120.0%。结论:该方法操作简便快速、灵敏度高,符合实际应用需要。     

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.     

Our Own Devices: Heterotopic Communication, Discourse, and Culture in the Information Society 1

The main premise of this article is that in information societies generally, and in virtual social contexts particularly, a distinctive style of interaction to facilitate the communication of difference, heterotopic communication , has emerged. It rests on two cultural foundations: an ideological belief in the positive, socially integrating power of communication, and a prevailing ethic of instrumental rationality, subjective individualism, and strategically practiced self-interest. The former is demonstrated by the use of simulation and spectacle as sources of information; exhibitionism/voyeurism as a communicative style; and the awareness of surveillance. The latter is seen in the competitive use of knowledge as a commodity; a surface globalism masking deep parochialism; lateral as well as vertical information inequity; and the use of public versus private as strategies for engagement rather than as spaces. Those who engage in heterotopic communication resort to their 'own devices' both in the sense of personal agendas, strategies, interests, and interpretations, and in the form of the telecommunication tools that help realize them. These personal and technological devices allow individuals with the right educational and technical resources to avoid exposure to disagreement, difference, or other information that does not serve their direct purposes or reflect their particular views of the world; yet they also help convey the appearance of openness, availability, and cooperation. This style of interaction is used strategically in combination with information and communication technologies to gain social or economic advantages, but it may encourage social separatism and parochialism, inhibit the negotiation of disputes, and emphasize competing interests.     

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