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1.
热带假丝酵母（Candida tropicalis）是长碳链二元酸发酵生产中的常用菌种，而热带假丝酵母突变株HP-2-48是一株高产DC12的优良生产菌株。本文对十二碳二元酸的发酵进行了研究，考察了青霉素钠盐、尿素、丙烯酸、pH值对菌体生长、产酸的影响并对其作用机制进行了讨论，并据此建立了长碳链二元酸新的发酵工艺。 相似文献
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海藻糖是一种由两个葡萄糖分子通过,α-α1,1糖苷键连接的非还原性双糖,广泛存在于微生物、动物和植物体内,对生物大分子的活性具有良好的保护效果,对生物体抗逆性起着重要作用。铝是地壳中含量最为丰富的金属元素,是一种严重的环境毒剂,在酸性环境中,对生物生长有重要影响。本文采用酿酒酵母菌株LK及其耐铝突变株LKt,分析它们胞内海藻糖含量的差异,研究铝胁迫下胞内海藻糖的变化。研究结果表明海藻糖含量的提高可明显增加酵母细胞在铝胁迫时的存活率。耐铝突变株LKt在铝胁迫下诱导产生海藻糖的能力显著高于原始菌株LK;酿酒酵母菌株中海藻糖诱导合成积累含量与其耐铝性存在密切正关系,是酵母主要耐铝机制之一。 相似文献
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采用60Co-γ射线的5个剂量（600Gy、800Gy、1 000Gy、1 200Gy、1 400Gy）,对直立型扁蓿豆[Melilotoides ruthenicus（L.）Sojak cv.Zhilixing]种子进行辐照诱导。结果表明,随着辐照剂量的增加,显著抑制其幼根的生长,但会促进其出苗;辐射后种子发芽势显著降低,但发芽率变化较小（除1400Gy辐照吸胀种子外,其他各处理的发芽率均达90%以上）。 相似文献
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用不同剂量^60Co-γ射线急性辐射处理整株粉掌铁兰后,测定不同处理叶片的酶活力。结果显示：粉掌铁兰的SOD活力均比对照降低,CAT活力的变化不大;POD活力的含量均比对照提高;PPO的活力10Gy处理的比对照降低,其它处理与对照相比均有所提高,其中80Gy处理的上升最多。辐射剂量与PPO活力呈极显著正相关,其相关系数为0．974。 相似文献
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发酵玉米芯酶水解液生产木糖醇的研究 总被引：5，自引：0，他引：5
假丝酵母(Candida sp.)菌株经驯化后显著地提高了对水解液中发酵抑制物质的耐受力,从而增加了木糖利用率和木糖醇得率。玉米芯经酶水解得到水解液,在30℃下采用假丝酵母菌株直接发酵生产木糖醇。对发酵条件进行了优化,优化结果为:接种量5%(体积比),种子龄20 h,氮源组成:2.5 g/L的酵母浸膏,2.5 g/L的胰蛋白胨,250 mL三角瓶装液100 mL,初始pH值6。在此条件下,木糖醇得率达65%。该方法大大降低了预处理的成本,显示了良好的应用前景。 相似文献
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目的:分析两性霉素B对医院口腔感染假丝酵母菌的失效性。方法:给予830例口腔感染患者两性霉素B治疗,初始3d的剂量是1、3、5 mg,加入5%葡萄糖溶液40 mg,保持速度是4 mL/h,从第4天开始每日增加4 mg,直至20 mg,后续保持该剂量;持续1~3个月的疗程,总用药量是1~1.5 g,并采用假丝酵母菌R因子检测方法分析两性霉素B对感染口腔假丝酵母菌的失效性。结果:从60株多重抗药性假丝酵母菌中分离出39株R因子,阳性率为65.5%,40株假丝酵母菌R因子的抗药性基因结构中3种以上抗药性基因者占有90%;结论:假丝酵母菌对两性霉素B的抗药性与传递R因子具有较强的关联性,利用R因子对两性霉素B对感染口腔假丝酵母菌失效性的分析具有安全和高效性的特征。 相似文献
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利用转座子Tn5-Mob系统,诱变普通田菁根瘤菌Rc6,Kmr菌落出现频率为3.0×10~(-7).从150个Km~r突变菌株中筛选出了3个结瘤延迟的突变株.并对结瘤突变株的形态、生理生化性质和质粒特性进行了研究.结果表明,突变株除了结瘤延迟和抗卡那霉素外,其它性状与野生型基本相同,它们均具有一个大小约200Md的质粒. 相似文献
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酿酒酵母(Saccharomyces cerevisiae)Hs27α菌株经UV诱变后,分别置于31℃、40℃等不同的温度下培养,结果表明:在胁迫温度40℃下培养,子代菌株中正突变菌株(指产酒量高于对照的菌株)的平均产酒能力明显高于31℃下培养的菌株。31℃下培养的正突变菌株的平均产酒量提高4.89%,而在40℃下培养的则为8.75%。用15种随机引物对出发菌株与UV诱变子代菌株进行总DNA的RAPD测验证明,在接近抑制生长的胁迫温度(本文为40℃)下培养获得的子代中,DNA水平的变异程度比在31℃的要高得多。这一方法较大幅度提高了酵母紫外诱变选育高产菌种的效率,也为酿酒酵母UV诱变机制的进一步研究提供了新途径。 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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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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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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《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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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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《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