共查询到20条相似文献,搜索用时 773 毫秒
1.
2.
3.
本体能够对特定领域的概念、术语以及关系提供一种形式化的描述方法.尽管本体在知识表示上有很强的能力,但是有一个缺陷,即不能表达不确定和不精确的信息.而这些信息在语义网和多媒体应用中,又是至关重要的.针对模糊信息的本体表示问题,本文对本体语言OWL DL进行了基于模糊逻辑的扩展,给出了形式化的语法和语义,并通过一个实例说明了该方法在表达能力上的灵活性. . 相似文献
4.
5.
6.
归纳学习的目的在于发现样例与离散的类之间的映射关系,样例及归纳的映射都需用某个形式化语言描述.归纳学习器采用的形式化语言经历了属性-值语言、一阶逻辑、类型化的高阶逻辑三个阶段,后者能克服前二者在知识表达及学习过程中的很多缺点.本文首先阐述了基于高阶逻辑的复杂结构归纳学习产生的历史背景;其次介绍了基于高阶逻辑的编程语言--Escher的知识描述形式及目前已提出的三种学习方法;复杂结构的归纳学习在机器学习领域的应用及如何解决一些现实问题的讨论随后给出; 最后分析了复杂结构归纳学习的研究所面临的挑战性问题. 相似文献
7.
8.
Web服务组合是Web服务的主要研究方向之一,对语义Web服务组合进行形式化描述并进行分析和验证是组合服务正确运行的保证.本文首先给出了基于有色Petri网的语义Web服务形式化模型,形式化描述了OWL-S的ServiceModel中8种基本的Web服务组合模式,利用这些组合模式可以构造出满足需求的组合Web服务.然后,对服务组合形式化模型的正确性分析和验证进行研究后,给出了组合模型语法正确性、可达性、活性和有界性的算法.最后,通过一个具体的建模实例展示了Web服务组合的Petri网建模. 相似文献
9.
在软件复用研究不断深入的情况下,构件的准确描述与高效检索已成为面向构件的软件复用研究的热点和难点.本文参照3C构件模型,提出一种基于形式化方法的、可扩展的构件描述模型,包括构件的功能描述、接口描述、环境依赖描述等,并保留了构件关键字、非功能属性等描述项.在此描述模型基础上提出了构件的分步检索法,并着重论述了包含四级模糊度的构件形式化检索方法,以提高构件的查找效率并兼顾查全率. 相似文献
10.
传统的MLS策略侧重于信息机密性保护,却很少考虑完整性,也无法有效实施信道控制策略,在解决不同安全级别信息流动问题时采用的可信主体也存在安全隐患.同时,应用环境的多样性导致了安全需求的多样化,而当前的安全模型都只侧重于其中一种或几种安全需求.本文给出的混合多策略模型一MPVSM模型有机组合了BLP,Biba,DTE和RBAC等安全模型的属性和功能,消除了MLS模型的缺陷,提高了信道控制能力和权限分配的灵活度,对可信主体的权限也进行了有力的控制和约束,同时为实现多安全策略视图提供了一个框架.文中给出了MPVSM模型的描述和形式化系统,并给出了几种典型策略的配置实例. 相似文献
11.
12.
13.
纵观医药营销的发展脉络,相继出现过"产品为王"、"利润为王"、"医生为王"、"渠道为王"、"品牌为王"和"终端为王"等理论,但是随着新医改的推进,"招标"、"配送"、"物价"、"目录",成为医药营销的先决条件。在新医改背景之下,2009年医药营销已进入"政府关系为王"的时代。所以理解政策与把握市场成为各企业的头等大事。 相似文献
14.
目的 探讨男性会阴部手术后伤口暴露疗法的可行性.方法 选择450例男性会阴部手术患者,其中250例术后伤口采用暴露疗法,200例术后伤口采用传统包扎疗法,术后观察伤口细菌感染和愈合情况,统计出伤口甲级愈合率,伤口细菌感染率,采用x2检验,用SPSS 17.0统计软件计算.结果 伤口甲级愈合率暴露疗法组为92.8%,明显高于包扎疗法组的91.5%(x2=12.2,P〈0.01).伤口细菌感染率暴露疗法组和包扎疗法组相近(x2=0.06,P〉0.05).结论 男性会阴部手术后伤口采用暴露疗法不会增加伤口细菌感染率,且伤口甲级愈合率明显提高. 相似文献
15.
目的 探讨男性会阴部手术后伤口暴露疗法的可行性.方法 选择450例男性会阴部手术患者,其中250例术后伤口采用暴露疗法,200例术后伤口采用传统包扎疗法,术后观察伤口细菌感染和愈合情况,统计出伤口甲级愈合率,伤口细菌感染率,采用x2检验,用SPSS 17.0统计软件计算.结果 伤口甲级愈合率暴露疗法组为92.8%,明显高于包扎疗法组的91.5%(x2=12.2,P<0.01).伤口细菌感染率暴露疗法组和包扎疗法组相近(x2=0.06,P>0.05).结论 男性会阴部手术后伤口采用暴露疗法不会增加伤口细菌感染率,且伤口甲级愈合率明显提高. 相似文献
16.
The concept that oestrogen replacement therapy is cardioprotective has been challenged recently by the negative results of randomized clinical trials in coronary heart disease. These data have come at a time of rapid advances in our understanding of the cellular mechanisms of oestrogen. In particular, the cloning of the classical oestrogen receptor (ERalpha), the identification of a novel ER isoform (ERbeta), the availability of specific ERalpha and ERbeta knockout mice models, and the elucidation of receptor functions and signalling pathways linked to non-genomic actions of oestrogen are helping to unravel this complex biology. In this article, these advances will be discussed with particular emphasis on the regulation of nitric oxide synthesis by oestrogen. Furthermore, the puzzling issues that have emerged and the potential for development of novel and specific therapeutic approaches will be highlighted. 相似文献
17.
On the action of bombesin on the kidney of the rat and the dog 总被引:1,自引:0,他引:1
18.
Eric Wenzler Kristen L. Bunnell Larry H. Danziger 《International journal of antimicrobial agents》2018,51(5):700-706
Background
There is a need to identify practice patterns of polymyxin use, quantify gaps in knowledge, and recognize areas of persistent confusion.Methods
A structured electronic survey was distributed to physicians, pharmacists and microbiologists. Demographic information was obtained, along with data regarding availability, stewardship principles, therapeutic usage, dosing, microbiological testing, and knowledge, attitudes and beliefs regarding the polymyxins.Results
In total, there were 420 respondents with a median of 8 (interquartile range 4–15) years of experience in infectious diseases (52.5%) and critical care (35%). Of the respondents who reported that only one polymyxin was available for use, 17.1% used polymyxin B. Over half (52.5%) of the respondents utilized a loading dose very often/always, and 66.8% dosed both polymyxins in milligrams, with the most common doses of colistin and polymyxin B being 2.5?mg/kg twice daily (60.3%) and 1.5?mg/kg twice daily (65%), respectively, for patients with normal renal function. Polymyxins were most often used for respiratory infections (63%) in combination with a carbapenem (63.6%). Approximately 85% of respondents reported their knowledge level to be fair, good or very good, although 34.9% answered two of the three knowledge questions incorrectly. More than 70% of respondents agreed that confusion exists in all surveyed areas of polymyxin use. Almost all respondents (91.2%) agreed that a polymyxin guideline would be a helpful resource.Conclusions
This survey revealed objective and subjective variability in the use and perception of the polymyxins, and identified several areas in which they were being used contrary to the available evidence. The information provided herein lays the framework to harmonize clinical practice, guide future research and shape consensus guidelines. 相似文献19.