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几丁质酶(Chitinase,EC3.2.1.14)作为一类糖基水解酶,可以水解几丁质的β-1,4-糖苷键,其降解产物广泛应用在抗虫、医药、食品等领域。随着几丁质酶理论基础和应用的研究日益受到重视,几丁质酶的研究已成为几丁质科学中的不可忽视的分支。本文综述了微生物几丁质酶的分类、结构、酶学性质及应用现状,以期为几丁质酶的进一步利用提供参考。 相似文献
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实验通过在土壤中以及在土壤中加入几丁质的方法对6株生防放线菌进行复壮,结果表明,6株生防放线菌均能在土壤中快速生长繁殖,且能够长期稳定存活;含有几丁质的土壤基质不仅有利于A3菌株生长繁殖,而且能够明显提高其几丁质酶的产生能力,从而改善此菌株的抑菌活性。 相似文献
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mRNA在细胞质内的稳定性是调控基因表达的重要方式。细胞以mRNA降解的方式对过时的、突变有害的mRNA进行及时清除以保证基因的正确表达和细胞正常的生命活动。其中脱帽酶Dcp1/Dcp2在mRNA降解中起到主要作用，但对其降解mRNA的详细作用机制了解甚少。到目前为止，尚没有该基因市售的抗体出现，阻碍了对该基因机理的研究。本文目的是利用PCR方法，从人的胎肝文库中克隆到Dcp2基因，制备其多克隆抗体血清。实验结果显示，通过溴化氰偶联柱子对该多克隆抗体血清经纯化得到的多克隆抗体，用于Western Blotting 试验，可以检测到该蛋白内源性的表达；用于激光共聚焦定位实验显示该内源性蛋白定位在细胞核内；此抗体同时可用于免疫沉淀实验。因此Dcp2基因和多克隆抗体的获得，为进一步研究该基因的功能创造了条件。 相似文献
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菲在多环芳烃(PAHs)家族中危害小,且兼具有PAHs共同的结构特点,因此,菲成为PAHs降解研究中的模式化合物.本文着重介绍了土壤中菲降解菌的原位筛选和鉴定技术,荧光原位杂交(fluo-rescence in situ hybridization,FISH)和稳定同位素探针技术(stable Isotopic probing,SIP).总结了不同菲降解菌对于菲的一般代谢途径.在此基础上,结合本人的科研实践,综述了目前对于参与菲降解过程中酶和基因研究的进展,特别是Rieske型氧化酶系统(Rieske oxygenase,RO)的研究.同时指出目前研究中存在的高通量原位筛选、基因调控研究等方面的不足,旨在为开展土壤微生物降解PAHs提供参考. 相似文献
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混凝土是用量最大。用途最广的一种建筑材料，因此，在混凝土工程施工中，如何控制混凝土质量问题发生，对保证工程质量有着重要意义。混凝土质量的好坏。对结构物的安全、造价有很大影响，所以，我们必须对混凝土施工质量问题发生有系统的防治措施。就从混凝土施工质量问题产生的原因和防治方面进行探讨。 相似文献
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乔传令 《科技成果管理与研究》2011,(6):103-104
几十年来,杀虫药剂主要是用来防治农业和卫生害虫,长期大量的使用使昆虫对这些杀虫药剂产生了抗药性,也即是在杀虫药剂的汰选之下昆虫体内已经产生了能够降解除杀虫药剂以外的多种化合物的解毒酶,克隆和应用这些降解酶用于清除环境中因防治害虫而残留的农药。 相似文献
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DMSP的生物合成与裂解及其在硫循环中的作用 总被引：1，自引：0，他引：1
二甲基巯基丙酸内盐(dimethylsulfoniopropionate,DMSP)是地球上最丰富的有机硫分子之一,也是微生物产生"冷室气体"二甲基硫(dimethyl sulfide,DMS)的最主要前体物质,在驱动全球硫循环和调节气候变化中均发挥着重要作用。同时,生物体内的DMSP还可能具有渗透压调节、抗氧化、冷冻保护、硫素贮存等功能。真核生物(主要是浮游植物)一直被认为是DMSP的唯一生产者,然而近期发现有着巨大生物量和活跃代谢能力的海洋α-变形菌纲细菌也可以合成DMSP,这使得异养细菌成为了海洋中DMSP潜在的重要来源。目前已分别从细菌和浮游微藻中鉴定出了一种和两种DMSP合成关键酶的编码基因。此外,海洋细菌还是DMSP的主要分解者,主要通过脱甲基通路(约占DMSP生物降解量的70%,不产生DMS)和裂解通路(约占DMSP生物降解量的30%,产生DMS)实现对DMSP的分解代谢。除细菌外,许多浮游植物和某些真菌也具有裂解DMSP产生DMS的能力。另外,DMSP裂解代谢通路有着很高的物种和遗传多样性,目前已知的DMSP裂解酶多达八种。本文着重对DMSP的生物合成和降解通路中可产生源活性气体DMS的裂解通路及其在硫循环中的作用等方面进行了系统阐述,对深入理解DMSP与DMS的产生机制及生态学效应具有重要科学意义。 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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《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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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