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901.
Adaptive XML to relational mapping: an integrated approach 总被引:1,自引:0,他引:1
Storing and querying XML (eXtensible Markup Language) data in relational form can exploit various services offered by modern relational database management systems (RDBMSs). Due to structural complexity of XML, there are many equivalent relational mapping schemes for the same XML data and queries. In this paper, we propose the adaptive XML to relational mapping (AX2RM) system, which considers finding optimal XML to relational (X2R) mapping as four separate but correlated procedures: logical database design, data scale estimation, workload transformation, and physical database design. We view the whole process as an autonomic computing problem and formalize the adaptive X2R mapping problem. Search spaces for each procedure are investigated individually, and five approaches for finding the optimal mapping are studied. We propose an integrated approach with greedy pruning (IT-GP), which views the mapping procedures as a whole and exploits heuristic rules in each procedure to prune impossible mappings as early as possible. Evaluation of these approaches shows the validity and high efficiency of IT-GP. 相似文献
902.
目的:研究胃癌患者外周血中调节性T细胞(T regulatory cells,Tr)的CD4 和CD25 表达与胃癌临床病理的关系,并分析其意义。方法:采用流式细胞术检测44例胃癌患者和10例健康体检者外周血CD4 CD25 Tr水平,并进行分层分析。结果:健康成人对照组外周血Tr表达率为(6.05±1.88)%,胃癌患者外周血CD4 CD25 Tr细胞占总CD4 T细胞的(15.27±4.06)%,与健康对照组比较,外周血CD4 CD25 Tr细胞比率均明显升高,差异有显著统计学意义(P<0.01)。分层分析显示,胃癌外周血Tr表达与淋巴结转移率和TNM分期有着负相关性,淋巴结转移阳性和TNM分期越晚,Tr表达率越高(P<0.05)。结论:胃癌患者外周血CD4 CD25 Tr细胞比率明显升高,并与患者免疫力低下及临床病理存在显著相关性,提示祛除人的CD4 CD25 Tr细胞是一种有效的治疗肿瘤的新方法。 相似文献
903.
We study the structure of the interregional inventor networks in Sweden by examining the residence of inventors and coinventors involved in Swedish patent applications to the European Patent Office. Several factors are found to influence the spatial affinity of regions. We find that spatial affinity extends beyond the region if it has less own R&D-related resources (business R&D, university R&D and patenting); if it is close to the other region and if it is relatively small. The resources of that other region plays a positive role if, in analogue fashion, that region has more R&D-related resources. 相似文献
904.
This paper evaluates the typically applied rules for awarding R&D subsidies. We identify two sources of inefficiency: the selection based on a ranking of individual projects, rather than complete allocations, and the failure to induce competition among applicants in order to extract and use information about the necessary funding. In order to correct these inefficiencies we propose mechanisms that include some form of an auction in which applicants bid for subsidies. Our proposals are tested in a simulation and in controlled lab experiments. The results suggest that adopting our proposals may considerably improve the allocation. 相似文献
905.
耐辐射异常球菌(D.radiodurans R1)osmC基因(DR_1538)编码的渗透诱导胁迫蛋白是一种在氧化胁迫中起重要作用的过氧化物酶.用PCR方法从耐辐射异常球菌中扩增出osmC基因的全长序列(441bp),采用原核表达系统对其进行表达纯化,获得了分子量大小约为18.7 kDa的带有His标签的融合蛋白.利用在线网站对OsmC蛋白的生物信息学分析,结果表明:OsmC蛋白由146个氨基酸组成,理论等电点为5.81,为亲水性蛋白;二级结构主要是由α-螺旋及不规则卷曲组成.OsmC蛋白的纯化及生物信息学分析为后续深入研究其功能奠定了基础. 相似文献
906.
分析了税收优惠政策对高技术企业RD投入的激励机制,并对美国、英国、加拿大、日本、韩国等国家的RD税收激励政策和我国科技税收优惠政策的改革及现行RD税收激励政策进行了分析,在借鉴国际经验的基础上提出我国科技税收优惠政策改革的思路。 相似文献
907.
以2010-2011年我国披露研发数据的沪市A股制造业上市公司为样本,共获得609个观察值.实证检验了CEO任职年限对企业创新投入强度的影响,在此基础上进一步探究CEO个人特征对上述影响的调节作用.得出以下主要结论:第一,企业研发投入强度随CEO任职年限的增加而下降,但下降的速度逐渐减慢.第二,CEO年龄和性别对其任职年限与研发投入强度之间的关系具有调节作用.最后根据实证研究结果给出了相应的对策建议. 相似文献
908.
This paper uses a unique survey to examine the nature and extent of knowledge flows that result from the international mobility of researchers whose initial education was in small island countries. Current migrants produce substantially more research than similar-skilled return migrants and non-migrants. Return migrants have no greater research impact than individuals who never migrate but are the main source of research knowledge transfer between international and local researchers. Our results contrast with previous claims in the literature that too few migrant researchers ever return home to have much impact, and that there is no productivity gain to researchers from migration. 相似文献
909.
A long stream of academic literature has established that public funding towards research and development matters for economic growth because it relates to increases in innovation, productivity and the like. The impact of public funding on the creation of new firms has received less attention in this literature despite theoretical constructs that support such association. In the present paper we study whether indeed there is a relationship between public research funds and local firm births in the context of the U.S. biotechnology industry. In doing so, we introduce a number of changes that strengthen the robustness of our findings when compared with existing literature. These changes include a direct measure of research expenditures and a considerably lengthier longitudinal dataset which allows us to capture a structural relationship and not a chance event. We empirically demonstrate that increases in the level of research funding from the National Institutes of Health towards biotechnology associate with increases in the number of biotechnology firm births at the Metropolitan Statistical Area level. Further, we reveal that public funds towards established firms associate with local firm births considerably more strongly when compared with funds towards universities and research institutes/hospitals. We conclude the paper with academic and policy implications of the present work that highlight the complexity of factors that underlie the creation of local firms in high technology industries. 相似文献
910.
We investigate how outside directors on supervisory boards influence innovative activities of the firms they advise and monitor. Based on panel data on the largest German companies, the econometric analysis shows a positive influence of external executives on innovative firm performance, measured by patent applications. Differentiating between outside directors from innovative and non-innovative companies reveals that only outside directors from innovative firms increase patenting activities at the firms they advise and monitor. This effect increases with the technological proximity between the appointing firm and the outsider's home firm. Outside directors from non-innovative firms are negatively associated with the appointing firm's innovativeness. The results indicate that external executives with an appropriate professional background can provide valuable specific knowledge and expertise to the board. 相似文献