共查询到20条相似文献，搜索用时 86 毫秒
1.
大黄鱼基因组DNA的提取及其RAPD分析条件的探索 总被引：9，自引：0，他引：9
通过实验筛选出一种快速、简便提取大黄鱼基因组 DNA的方法 .以该法提取的大黄鱼基因组 DNA为模板 ,对大黄鱼 RAPD分析中的 DNA模板浓度、镁离子浓度、d NTPs浓度、引物浓度和 Taq酶浓度进行了研究 ,初步确定了适于大黄鱼 RAPD分析的最佳反应体系 :2 5μL反应体系中 ,含模板 DNA2 5 ng,1 0× PCR缓冲液 2 .5μL,d NTPs1 0 0μmol/L,Mg Cl2 2 .5 mmol/L,引物 0 .2μmol/L,Taq DNA聚合酶 1 .0 μmol/min. 相似文献
2.
以羽毛为底物发酵产角蛋白酶培养基的优化 总被引：1，自引：0，他引：1
以角蛋白酶为考察指标,采用正交试验对以羽毛为底物,利用枯草芽孢杆菌菌株KD-N2生产角蛋白酶的培养基组成进行了优化试验.结果表明在NaCl含量为0.5 g/L,MgSO4含量为0.2 g/L,KH2PO4/K2HPO4含量为0.35/0.7 g/L时有利于角蛋白酶的产生,验证试验证明发酵24 h时角蛋白酶活性为(66.5±2.04)U/mL:各组发酵液pH值均呈上升趋势,发酵残留物重量也随发酵培养基组成不同而呈现一定的差异,表明以羽毛为底物发酵产角蛋白酶为一复杂过程.以天青角蛋白和酪蛋白为底物对酶活测定的结果表明了实验方法和结果的可靠性. 相似文献
3.
拜氏梭菌(Clostridium beijerinckii〗)NRRL-B593在葡萄糖基质中可以代谢产生丁醇、乙醇、异丙醇。乙醇脱氢酶(ADH)是产生醇类的关键酶,比较了拜氏梭菌(C.beijerinckii)NRRL-B593在葡萄糖基质与氨基酸基质中ADH活性,为进一步研究该菌株的代谢及表达调控提供理论基础。首先通过监测C.beijerinckii NRRL-B593在不同培养基中D_(600)值,绘制生长曲线,后在8000 r/min,10min下收集对数期与稳定期的细胞,利用厌氧型细胞破碎仪French Press获得无细胞抽提物(CFE),最后通过Bradford法测量蛋白质含量,在厌氧条件下利用丙酮为底物,NADPH依赖型的氧化反应测其酶活力。结果显示,稳定期的ADH酶活力远远高于对数期酶活力高,氨基酸培养基中的ADH酶活力高于葡萄糖培养基。 相似文献
4.
本研究建立了一种方便快捷地检测DNA双链断裂引起的基因重组的方法。传统的检测DNA双链断裂的方法较为复杂、繁琐。因此,构建简单、快速的此类检测技术是非常必要的。本研究构建了利用正向重复片段的GUS基因载体以及引导RNA和噬菌体MS2外壳蛋白偶联限制性核酸内切酶的基因组编辑系统,在GUS基因内部DNA重复区切割DNA,导致双链断裂(double-strand breaks,DSBs),DSB经同源序列引导修复(homology-directed repair,HDR)途径,引起GUS基因重组,恢复其功能。此方法可以经过GUS染色后快速、直观地检测位点特异的DSB。通过GUS与其底物的反应,以达到半定量、直观快速检测DSB的目的。 相似文献
5.
6.
目的:建立一种高效液相色谱法测定玫芦消痤凝胶中苦参碱的含量.方法:用十八烷基硅烷键合硅胶为填充剂;以0.2％磷酸溶液-三乙胺-乙腈(96∶0.2∶4)为流动相;流速为1.0ml/min;检测波长为210nm.结果:苦参碱与其它成分分离良好,在0.1～1.0μg浓度范围内,苦参碱进样量与峰面积呈良好的线性关系;平均加样回收率为99.67％,RSD为1.40％;中间精密度试验不同分析人员之间的RSD为1.25％,小于3.0％;样品溶液在8小时内稳定;重复性RSD为1.23％,小于3.0％;苦参碱的检测限为0.5ng.结论:该方法简便、快速、准确,可以作为玫芦消痤凝胶中苦参碱的含量测定方法. 相似文献
7.
8.
9.
关于应用酶法分析测定微量无机物的可能性已有评述。本文研究了在葡萄糖氧化酶一过氧化物酶一邻联二茴香胺偶联反应中的有关无机激活剂与抑制剂的情况,目的是从中发现可供分析测定某些相应微量无机元素的反应,并建立相应的分析方法。这个偶联反应是:生成的有色产物可在440nm波长下用分光光度法测定。单位时间里产生的产物量即表示了在该条件下此偶联反应中的前一反应的反应速度,因为后一反应在有过量过氧化物酶存在下是一个快反应。实验中使用的酶溶液是用SIGMA化学厂的葡萄糖氧化酶(glucose Oxidase.E.C.1.1.3.4.Type Ⅱ 17300单位/克)4mg溶于100ml水中为甲液,再用甲液稀释五倍为乙 相似文献
10.
枇杷果肉制成丙酮粉,经硫酸铵分级沉淀、透析,DEAE-纤维素柱层析、ACA_(34)柱层析和FPLC分离等方法,分离和纯化得到多酚氧化酶的两个同工酶(酶A和酶B).酶B由一个或几个分子量为42×10~3D的亚基组成.酶的动力学研究表明:酶A、酶B的K_m(多巴胺为底物)均为2.40×10~(-3)mol/L,以邻苯二酚为底物时,酶A和酶B的K_m分别为0.163×10~(-3)mol/L和1.54×10~(-3)mol/L.酶底物特异性表明,酶B是邻位二酚酶,不能作用于单酚和间位二酚. 相似文献
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.
《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
13.
《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
14.
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
15.
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
16.
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
17.
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
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