共查询到20条相似文献，搜索用时 93 毫秒
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利用均匀设计法对Bacillus sp．ZJU318产酶的最佳培养基进行了快速优化研究。结果表明，其最适产酶培养基为：3．28％黄豆粉，0．023％蔗糖，0．075％K2HPO4，配制时的pH为12（灭菌后pH为8～9）；此外，其发酵的最佳条件为：发酵温度28℃，接种量20％，摇瓶装量20mL（250mL三角瓶）。在最适的发酵条件下，脂肪酶的发酵水平可达24．7U／mL。Bacillus sp．ZJU318脂肪酶作用的最适温度为45℃，40℃保温1h，活力几乎没有损失；但是，在50℃和60℃的条件下保温1h后，酶活降低得比较明显；酶作用的最适pH为9．0。在pH7～10，该脂肪酶较稳定，但是在酸性的环境中，酶的稳定性较低。 相似文献
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以长宁某页岩气田作业现场的压裂返排液为研究对象,通过对其水质特征、治理现状进行分析,提出了"絮凝沉降-氧化降解"预处理工艺。通过实验研究,确定了性能优良的明矾絮凝剂、高铁酸钾氧化剂,得出最佳实验条件:在pH值为10,絮凝剂明矾投加量为1000mg/L的条件下,快速搅拌3min,慢速搅拌15min;然后以絮凝沉降处理后的出水作为氧化降解的入水,同时在高铁酸钾投加量为1200mg/L,pH值为5,氧化处理1h的最佳工艺条件下,对页岩气压裂返排液进行处理。处理后的废液主要污染指标COD_(Cr)降低了83.24%,TOC降低了92.20%,TN降低了36.01%,色度降低了93.75%,从而为达标排放创造了条件。 相似文献
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以还原糖含量为指标,在不加酶的情况下,研究了温度对大麦淀粉中水溶性还原糖的影响,并以此为依据选择中温淀粉酶对大麦淀粉进行水解。通过单因素试验确定:在料水比为1∶25,温度60℃,时间15min,pH6.0(自然pH),加酶量为7.5μ/g的条件下,可以使大麦淀粉水解为DE值8～10的糊精。 相似文献
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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
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《内蒙古科技与经济》2019,(23)
采用滴速滴量可控的注射泵,以液相离子交换法制备磷酸银光催化剂并用于可见光下降解亚甲基蓝,降解率最高为83.21%。此种方法制备纳米磷酸银最佳条件为:微量注射泵的滴速为3ml/min,反应物为AgNO_3与Na_2HPO_4,溶剂纯水。磷酸银光催化降解亚甲基蓝最佳条件为:催化剂量为200mg/L,反应时间40min,反应液pH值为5。X射线衍射仪及扫描电子显微镜结果表明,磷酸银为简单立方晶型,平均粒径为150nm。以亚甲基蓝为目标降解染料,研究了磷酸银质量浓度、亚甲基蓝初始浓度、体系pH值、磷酸银形貌对其光催化性能的影响。重复性实验证明磷酸银光稳定性差,5次重复使用后,降解率降至13.74%。 相似文献
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为解决青菜干制中的叶绿素保存问题,在100℃下烫漂1～5min。发现随烫漂时间增加,叶绿素含量从1min的96%降到5min的80%。烫漂3min可杀死过氧化物酶,此时叶绿素保存率为91%,护色效果较好。在pH7.0至pH8.3烫漂液中烫漂,发现在pH7.3时,叶绿素保存最好,其含量为92.98%。在烫漂液中加0.05%的Mg2+或Zn2+离子,处理后总叶绿素比对照组要高,Zn2+的处理效果略优于Mg2+处理。烘制温度从60℃至80℃,发现烘制温度越低叶绿素保存越好。在60℃下,1cm厚,烘制3h,能较好地保存叶绿素。 相似文献
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以海带为原料,采取热水浴提取法探讨海带中可溶性粗多糖的提取方法,探究提取时间,提取温度,提取pH以及料液比对于多糖提取率的影响。通过单因素试验以及正交试验得出海带多糖提取工艺在料液比1g:40mL的条件下的最佳工艺组合为:提取温度80℃,提取时间4.5h,提取pH 8.0。在此最佳工艺组合下多糖提取率为5.41%。 相似文献
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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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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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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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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
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《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
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《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
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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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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
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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