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1.
本文研究β修正光度法测定工业废水中痕量砷，它能消除过量ＢＲＢ的干扰提高分析敏度、精密度和准确度。结果表明砷浓度０－０．４０ｍｇ／Ｌ时，修正吸光度有良好线性关系，检出限０．００４ｍｇ／Ｌ，加标回收率９３．０％－１１１％，相对标准偏差ＲＳＤ≤６．５％，该方法适合于化工废水、城市污水及各种环境水质分析。 相似文献
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本文系统地研究了甲硝唑在汞电极上的电极过程，证明了该电极过程为一含有吸附作用的不可逆的扩散控制过程，电子转移数为４，不可逆系数ａ＝０．７１４．建立了甲硝唑的单扫示波极谱测定法，在０．２０ｍｏｌ／Ｌ的ＮａＣｌ溶液中，于－０．７１Ｖ（ｖｓＳＣＥ）处的峰高与浓度［（０．０２─８０）ｍｇ／Ｌ］间存在良好的线性关系，检测限为２．４μｇ／Ｌ，ＲＳＤ＝２．０％（ｎ＝８），并考察了人体内常见微量物质对的影响。 相似文献
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茶多酚抗突变和消除自由基作用的研究 总被引：6，自引：0，他引：6
采用Ｅ．ＣｏｌｉＳＯＳ显色法，小鼠骨髓细胞微核及染色体畸变试验和体外自由基消除实验等方法测定了茶多酚复合物（ＴＰ）的抗突变和消除自由基作用．结果表明：（１）ＴＰ的终浓度在２．５和５ｍｇ／ｍｌ时，对由阳性致突变物ＭＮＮＧ，ＥＭＳ和ＮａＮ＿３诱导的ＳＯＳ应答反应均具有明显的抑制作用；（２）小鼠每日ｉｇ４０、８０和１２０ｍｇ／ｋｇ剂量的ＴＰ能明显抑制由环磷酰胺（ＣＰ）诱发的骨髓ＰＣＥ的ＭＮＣＦ，三种剂量ＴＰ的抑制率分别为４０．９８％、６６．７６％和６５．９４％；（３）ＴＰ对ＭＭＣ诱发的骨髓细胞染色体畸变（ＣＡ）的抑制率分别为６２．５６％、５５．７１％和４７．９５％；（４）在Ｘ／ＸＯ－ＥＳＲ、Ｘ／ＸＯ／Ｌｕｍｉｎｏｌ－ＢＣＬ和ＩＲ／ＮＢＴ－ＳＰＭ三种模型中ＴＰ对超氧阴离子Ｏ＿２自由基均具有极强的消除作用，消除率分别为９８±６％、９８±１．２％和９５±１．５％，对Ｏ＿２的消除效率明显强于维生素Ｃ和Ｅ，对不同工艺制备的ＴＰ消除活性氧自由基作用的测定结果显示：脱咖啡碱程度高，ＥＧＣ和Ｌ－ＥＧＣＧ含量比例高的ＴＰ－３制剂消除Ｏ＿２的效率最高．因此，ＴＰ消除有害自由基，中断或终止自由基的氧化反应是抗突变，抗肿瘤作用的主要机制 相似文献
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一阶导数光谱法测定杞菊地黄丸中丹皮酚含量 总被引：2，自引：0，他引：2
杞菊地黄丸为滋肾养肝药,由八种中药组成,本文采用一阶导数光谱法,不经分离对丹皮酚进行含量测定,实验证明,用△Ａ＝Ａ２６７－Ａ２６３测定其含量较准确,在３．０１８～８．０４８ｍｇ／ｍｌ浓度范围内呈良好线性关系,回归方程Ａ＝０．００３７２４＋０．０１４０６Ｃ、ｒ＝０．９９９６,回收率为１０１．９５％（ＲＳＤ＝１．７４％ｎ＝５）。 相似文献
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采用梯度淋洗离子色谱法对碱金属、碱土金属及其铵类进行分析，该方法采用ＣＧ３分离柱，０．３ｍｍｏｌ／ＬＨＣｌ为淋洗剂，４ｍｉｎ后改用３．０ｍｍｏｌ／Ｌ盐酸间苯二胺和５．０ｍｍｏ１／ＬＨＣｌ作淋洗剂（流速２．０ｍｌ／ｍｉｎ）采用微膜抑制柱，再生液为５０ｍｍｏｌ／ＬＫＯＨ（流速２．０ｍｌ／ｍｉｎ），用电导检测法分别检测Ｌｉ￣＋、Ｎａ￣＋、ＮＨ、Ｋ￣＋和Ｍｇ￣（２＋）、Ｃａ￣（２＋）、Ｓｒ￣（２＋）、Ｂａ￣（２＋）．对分析条件进行了探讨． 相似文献
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本试验采用西藏著名野生花卉蓝玉簪龙胆茎段为组织培养材料,通过多次试验后确定：蓝玉簪龙胆的启动培养中适宜的培养基为;ＭＳ＋ＮＡＡ０．５（ｍｇ／１,激素单位下同）＋ＢＡ０．５－１．０,每茎段平均分化形成４．２个芽;诱导愈伤组织的适宜培养基为ＭＳ＋ＢＡ０．５＋ＮＡＡ０．５－１．０; 相似文献
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乳清酸的单扫示波极谱研究 总被引：1，自引：0，他引：1
乳清酸在０．１ｍｏｌ／ＬＨＣｌＯ４＋０．０２ｍｏｌ／ＬＮａＣｌＯ４底液中，于ＪＰ－２型示波极谱仪上，有一良好的二阶导数峰Ｅｐ＝－０．８６０±０．０１Ｖ（ＳＣＥ），浓度在１×１０－７～６×１０－５ｍｏｌ／Ｌ范围内，与峰高成线性关系，检测限为７．５×１０－８ｍｏｌ／Ｌ．实验证明，电极过程为具有催化性质的双电子可逆过程． 相似文献
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报告１０８例病毒性肝炎患者血清总补体（ＣＨ＿（５０））和Ｃ＿３值的检测结果：急性肝炎的ＣＨ＿（５０）为６８．４±６．１３单位／ｍｌ，Ｃ＿３为１３０．２±６．６７ｍｇ％，均高于正常组（ＣＨ＿（５０）为４８．５±５．７５单位／ｍｌ，Ｃ＿３为１０２±５ｍｇ％），Ｐ＜０．０１；其他类型的肝炎患者组的补体均低于正常组，Ｐ＜０．０１．补体的含量与Ｔ细胞花环（Ｅｔ花环）呈中度相关，与ＧＰＴ呈高度相关，因此测定ＣＨ＿（５０）和Ｃ＿３可作为衡量患者机体免疫功能和判断病毒性肝炎预后的指标之一。 相似文献
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用超细玻璃纤维滤膜收集城市交通干道空气中的铅,硝化后使用石墨炉原子吸收分光光度法测定。本法具有灵敏度高,精密度和准确度较好等优点。铅平均浓度在１０．５７～６６．６７μｇ／Ｌ时,其相对偏差在０．４７％～５．７％之间,标准差在０．１８～０．３３之间,ＣＶ在０．４７％～３．０３％之间,标准曲线的相关系数为０．９９８。 相似文献
11.
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
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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
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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
14.
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
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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
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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
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Milton Mueller 《The Information Society》2001,17(3):151-163
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. 相似文献
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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.…… 《中国科学院院刊(英文版)》2008,22(1):15-15
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. 相似文献
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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
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《中国科学院院刊(英文版)》2014,(3)
<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 相似文献