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1.
以三种植物为材料,对其角果的碳酸酐酶活性的日变化和相应的净光合速率的日变化以及不同长度角果的CA活性和净光合速率关系进行研究。结果表明,在日变化中,油菜和诸葛菜的CA活性与净光合速率之间存在显著性正相关,羽衣甘蓝则不明显。但不同长度角果的CA活性与净光合速率之间三种植物都呈显著相关,这说明植物的生殖器官角果,CA活性的高低对净光合速率有较大的影响。 相似文献
2.
介绍了一种用于主动信息服务业的《CA》论文收录的检索策略 .利用刊物形式的《CA》以手工检索为基础 ,借助《中国科技论文与引文分析数据库》,实现了对《CA》论文收录作者名、址追踪 ,对检索效果进行了综合评价 ,并分析了影响检索效果的若干因素。 相似文献
3.
对应分析在多时相遥感影像分类前变化检测中的应用——以江苏省盐城市为例 总被引：1，自引：0，他引：1
利用对应分析(Correspondence Analysis,CA)对江苏省盐城市及周边地区两个不同时相影像进行土地利用/土地覆被(land use/land cover,LULC)变化检测.在对两幅辐射归一化影像采用CA算法进行变换后,将二者的第一主成分(Principal Component 1,PCI)相减得到差值影像,利用总体精度(Overall Accuracy)曲线,经反复试验,最终设定±1.6δ作为上下限最佳阈值,对差值影像进行密度分割(Density Slice),并提取出研究区域的植被变化信息.在利用混淆矩阵与主成分分析(Principal Component Analysis,PCA)所得的结果对比中发现,CA变换变化检测的结果要明显优于传统的PCA变化检测的结果.CA结果显示,CA变换变化检测结果的总体精度为89.60%,卡帕系数(Kappa Coefficient)为0.8194,比PCA变化检测结果卡帕系数提高近0.1,由此可见,CA变换可以作为用于检测土地覆被变化的一种有效的多元统计分析技术. 相似文献
4.
尖锐湿疣(Condyloma acuminata,CA),生殖器疣(阴部疣)、性病疣,此病被公认为性传播疾病,也是现代社会最常见的性传播疾病之一.应用核仁组成区嗜银蛋白银染方法对34例CA与宫颈癌进行AgNOR定量观察,揭示CA与上皮不典型增生性病变、宫颈癌之间的关系. 相似文献
5.
目的:探讨血清糖类抗原CA199糖类抗原CA724癌胚抗原CEA在结直肠癌的TNM分期中的临床应用价值。方法:观察组结直肠癌患者100例与对照组同期非消化道肿瘤的住院病人100例,空腹抽取静脉血,采用罗氏公司E601电化学发光全自动免疫分析仪和罗氏原装试剂盒检测血清中CEA、CA199、CA724值。应用SPSS 17.0软件进行统计学处理,计量资料以均数±标准差f±s)表示,采用单因素方差分析进行统计,计数资料采用X-2检验,P0.05为差异有统计学意义。结果:在单项检测中,CEA的敏感率最高,达37%,且CEACA199CA724.在两项联合检测中CA199+CEA的敏感度最高达53%,三项联合检测敏感度达64%,在各种联合检测中最高。三项肿瘤标志物的阳性率和升高水平随肿瘤的TNM分期的增加而递增。结论:三项肿瘤标志物的单一检测敏感度较低,肿瘤标志的联合检测结直肠癌可以提高敏感性,以CEA+CA199+CA724的效果最好,CA199+CEA次之。CA199、CA724、CEA三项肿瘤标志物的阳性率及升高水平依肿瘤的TNM分期的增加呈递增趋势。 相似文献
6.
普通车床数控化改造,能够解决机械制造中复杂技术的问题,并可以提高生产效率,稳定其加工质量。本文选择普通车床CA6140为数控化改造对象,从普通车床数控改造的主要关键技术着手,对CA6140普通车床数控化改造应用进行了探析。 相似文献
7.
尖锐湿疣（Condyloma acuminata，CA），生殖器疣（阴部疣）、性病疣，此病被公认为性传播疾病，也是现代社会最常见的性传播疾病之一。应用核仁组成区嗜银蛋白银染方法对34例CA与宫颈癌进行AgNOR定量观察，揭示CA与上皮不典型增生性病变、宫颈癌之间的关系。 相似文献
8.
基于移动Ad Hoc网络的PKI/CA系统互操作模型 总被引：2，自引：1，他引：1
移动Ad Hoc网络(MANET)是由若干无线移动节点组成的不依赖于任何固定基础设施和集中式组织管理机构,而通过节点间的相互协作进行网络互联的一种多跳自组织临时性自治网络系统。在建立移动Ad Hoc网络多域全分布式PKI／CA系统过程中,在对国内外互操作技术及模型进行研究的基础上,提出了扩展推荐信任模型及相应的CA互操作结构模型,通过动态信任路径管理模式和认证机构信任列表实现CA间信任关系的管理和维护,提高了系统的安全性、可伸缩性和鲁棒性。 相似文献
9.
林跃 《中国科技期刊研究》2005,16(2):190-192
对美国《化学文摘》(CA)收录的中国期刊种数、文献量及文献类型作了统计分析，并与发达国家进行比较。数据显示，我国实行改革开放政策以来，被CA收录的科技期刊种数及其文献数量迅猛增长，进入CA千种表的期刊种数也同时增加，其中英文版期刊数稳定增长，尤其在CA收录期刊的前500名中，我国期刊的占有量明显提高，但是被收录文献的数量和类型尚存一定的局限性。 相似文献
10.
CA(条件接收)系统在数字电视中有着重要的地位,是体现数字电视个性化、保障数字电视增值业务发展的关键,因此CAS的安全性显得尤其重要.本文就现有的CA系统防御方法进行了分析,并结合在网络安全中应用发展的主动防御技术,提出了一种新的CA系统主动防御体系. 相似文献
11.
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
12.
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
13.
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
14.
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
15.
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
16.
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
17.
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
18.
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
19.
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
20.
《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