共查询到20条相似文献，搜索用时 281 毫秒
1.
2.
本实验采用磷钼蓝分光光光度法对合肥市场的十一种品牌无磷洗东粉进行磷含量的测定。在测定条件下,绘制标准工作曲线,得到的磷标准曲线方程为：A=0．4046C＋0．0072,（R2=0．9937）,线性关系良好,从所抽查样品洗衣粉的测定结果发现,磷含量最高为23.114％,最低为0．0190%。 相似文献
3.
[目的]对离子色谱法测定水中硝酸盐进行方法确认,来判断本实验室是否具备该方法的检测能力。[方法]列出本方法的仪器设备条件和标准曲线、标准样品、精密度、检出限。[结果]标准曲线r=0.9999;对标准样进行6次平行测定,测得标准偏差S=0.0011,相对标准偏RSD=0.138%;标准偏差S=0.0014相对标准偏差RSD=0.131%;标准偏差S=0.0040,相对标准偏差RSD=0.045%,检出限0.021mg/L。[结论]通过对检测数据的分析,确认本实验室具备开展此项目的检测能力。 相似文献
4.
目的建立紫外分光光度法测定四合木中总黄酮的方法。方法采用岛津UV-2550紫外分光光度计对四合木中总黄酮的含量进行测定。结果四合木总黄酮的标准曲线回归方程A=1.4378C 0.0083,其相关系数R=0.9998。结论本实验建立的测定方法具有准确、简便、重现性好的优点,适合用于四合木中总黄酮含量的测定。 相似文献
5.
目的建立紫外分光光度法测定苦苣菜中总黄酮的方法。方法采用岛津UV-2550紫外分光光度计对苦苣菜中总黄酮的含量进行测定。结果苦苣菜总黄酮的标准曲线回归方程A=1.1801C 0.0094,其相关系数R=0.9999。结论本实验建立的测定方法具有准确、简便、重现性好的优点,适合用于铁棒锤中总乌头碱含量的测定。 相似文献
6.
目的建立紫外分光光度法测定铁棒锤中总乌头碱的方法。方法采用岛津UV-2550紫外分光光度计对铁棒锤中总生物碱的含量进行测定。结果乌头碱对照品的标准曲线回归方程A=1.2757C 0.0016,其相关系数R=0.9998。结论本实验建立的测定方法具有准确、简便、重现性好的优点,适合用于铁棒锤中总乌头碱含量的测定。 相似文献
7.
本文建立科学的检测气相防锈包装纸中金属离子铅的含量的方法,系统的研究了试样的不同浸提条件对金属离子铅的浸提量的影响,考察了浸提液的浓度、温度、和浸提时间等因素,用火焰原子吸收分光光度计测其吸光度值。根据标准曲线回归方程计算提取金属离子铅的浓度再计算加标回收率。结果表明：对于气相防锈纸中的金属离子铅的测定,在仪器的最佳工作条件下：测量得铅的回归方程为方程为;y=0.0193x＋0.0032相关系数R2=0.9972。加标回收率为36.26%～101.1%。方法应用于实际样品的测定,结果满意。 相似文献
8.
对药品辅料中甲醛次硫酸氢钠的检测方法进行改进,以增大方法的提高灵敏度、稳定性。方法:参照国标GB/T21126-2007,采用Wateres2695高效液相色谱仪对食品中甲醛次硫酸氢钠进行测定。结果:高效液相色谱仪测定甲醛次硫酸氢钠的测定平行进样RSD小于2%,标准曲线时相关系数能达到0.999以上,平均回收率为94.8%,最低检出限为0.02μg/mL。对不同种类食品的前处理方法、液相色谱的条件标准曲线的制备进行了改进,并取得了一定的成效。结论:改进后测定甲醛次硫酸氢钠的方法精密度高、准确度好、完全能满足食品中甲醛次硫酸氢钠的定性定量分析。 相似文献
9.
建立了一种测定环境水样中碘化物的离子色谱-电导检测方法,优化了色谱条件,结果表明该方法灵敏度高,标准曲线相关性好,精密度高,准确度好,检测结果准确可靠。 相似文献
10.
11.
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
12.
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
13.
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
14.
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
15.
《中国科学院院刊(英文版)》2008,22(1):2-3
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. 相似文献
16.
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
17.
《中国科学院院刊(英文版)》2008,22(1)
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." 相似文献
18.
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
19.
Leah A. Lievrouw 《The Information Society》2000,16(2):155-159
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. 相似文献
20.
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