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嵌入式实时系统多数应用在安全性要求较高的场合,因此需要保证系统的正确性.复杂性不断增加的实时系统迫切需要在系统开发早期引入形式化分析技术来验证系统的期望性质.时间Petri网是有严格数学基础的图形表达工具,适合对实时系统建模;时间自动机(Timed Automata,TA)有成熟的验证工具,被广泛用于实时系统的模型检验和验证.本文提出一种基于着色时间Petri网(Colored Time Petri Net,CTPN)的实时系统的验证方法,用CTPN对带有控制流和数据流的实时系统建模,通过转换规则将CTPN模型转换成语义等价的TA模型,利用模型检验工具UPPAAL验证系统的性质.最后,用实例证明此方法有效. 相似文献
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多水平模型的最新进展 总被引:5,自引:0,他引:5
多水平模型 ( Multilevel Models)又称随机效应模型( Random Effect Models) ,它是在二十世纪八十年代 ,由英美教育统计学家基于方差成分分析而提出的统计模型 ,用于研究具有层次结构或嵌套式结构的数据 ,如分层抽样或整群抽样的数据。设个人处于家庭中 ,家庭处于社区中 ,这就构成三个水平 :个人是基本水平 (水平 1) ,家庭是中间水平 (水平 2 ) ,社区则是最高水平 (水平 3 )。多水平模型方法指出 ,数据可以而且应该同时在所有的水平上收集和分析 ,这可避免聚合带来的缺陷 [1 ]。以往通常忽略层次或对高单位设立哑变量 ,这会损失数据所包含… 相似文献
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复吸行为是禁戒毒工作的一个关键性问题。对戒毒人员开展防复吸戒治,降低其复吸风险,对于促进社会安定和公共卫生安全具有重要的意义。但是,降低戒毒后的复吸是一个复杂的系统性工程,需要进行生理-心理-家庭-社会等多层面的康复治疗干预。行为改变轮理论(Behaviour Change Wheel, BCW),被广泛应用于临床康复训练领域,取得了较好的效果。这一理论综合了个人、环境与社会政策等多方面的因素来改变和影响某一行为问题,与复吸行为的综合戒治要求具有高度一致性,能较好地应用到戒毒人员复吸行为的康复训练之中。本研究基于行为改变轮理论的原理和操作技术,探索构建甲基苯丙胺戒毒人员防复吸戒治模型,对毒品成瘾的防复吸戒治提出新的思考和戒治模式,可为禁戒毒实务部门提供一种新的工作借鉴。 相似文献
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目的:为血药浓度的检测提供一条简便、无创、相关性高的途径。方法:在经典的药代动力学模型基础上进行扩展,提出血药浓度与尿药参数之间的函数关系式,并给出不同服药模式下血药浓度的测定方法。然后,对该模型的相关性及稳定性进行验证:首先取得一组测定的关于人体片剂服药模式的在不同时间下药物(氨基)导眠能的血药浓度与尿药参数的对应值,将(氨基)导虑能的药代动力学参数、测定的尿药参数及时间代入理论模型算出理论血药浓度值,并与实际测得的血药数据进行相关性对照;然后同理对一组关于人体静脉注射服药模式下相关数据均已测得的药物x进行相关性检验。结果:(氨基)导眠能的理论与实际血药浓度总体方差为10.7%,其准确性已能被临床所接受;药物x的理论与实际血药浓度总体方差为0.183%,两组数据几乎完全吻合。结论:该模型有良好的相关性,可作为独立的一种血药浓度检测手段使用。 相似文献
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Macrophages from mice pretreated with two chemically synthesized immunostimulating aryl-oligopeptides, FR41565 and FR48217, inhibited the multiplication of herpes simplex virus type 1 (HSV-1) and type 2 (HSV-2) in monkey Vero cells, and that of vesicular stomatitis virus (VSV) in murine L929 cells. In addition, the aryl-oligopeptides protected mice against a lethal HSV-1 infection. In particular, when treated with FR48217 at 6 mg/kg, all mice survived, whereas all control mice died from the HSV-1 infection. 相似文献
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Background: At global, national, and local level, the need for ongoing, timely and cost efficient, comprehensive drug treatment monitoring, and evaluation systems have clearly been well recognized. Objectives: To test the feasibility of linking laboratory data and client intake data and its usefulness for modeling retrospectively, for the first time, 5-year longitudinal drug treatment outcomes in an Irish opiate treatment setting. Methods: A multisite, retrospective, longitudinal cohort study was implemented to evaluate outcomes for opiate users based on 1.7 million routine urinalysis results collected from 4,518 individuals presenting for opioid substitution treatment in Ireland from January 2006 to December 2010. Results: Analysis of opiates, cocaine, benzodiazepine, and cannabis use at treatment intake, 6 months and at 1–5 year follow-ups revealed differences in urinalysis protocols; significant differences in age of first drug use between those using and not using opiates at 5 years; significant decreases in opiate use; increases in benzodiazepine use and significant increasing effects of concurrent cocaine and benzodiazepine use on the odds of using opiates. Time series analysis of weekly proportions opiate positive predicted 16% (95% confidence interval: 7%–25%) of clients would be opiate positive 5 years postinitial intake. ConclusionsImportance: Underutilized urinalysis data can be used to address the need for cost effective, efficient evidence of drug-treatment outcomes across time, place, and systems. Linking and matching the cross-sectional data across sites and times also revealed where improvements in electronic records could be made. 相似文献
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M Nishimura H Nakada S Takase A Katayama T Goto H Tanaka M Hashimoto 《The Journal of antibiotics》1989,42(4):549-552
The structure of FR900840, a new antitumor antibiotic produced by a strain of Streptomyces has been deduced as 1 on the basis of spectroscopic and chemical evidence and finally confirmed by synthesis from L-threonine and L-serine. 相似文献
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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
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Fujine K Tanaka M Ohsumi K Hashimoto M Takase S Ueda H Hino M Fujii T 《The Journal of antibiotics》2003,56(2):55-61
Novel immunosuppressive agents, FR252921, FR252922 and FR256523 were isolated from the cultured broth of a bacterial strain No. 408813. The strain was identified Pseudomonas fluorescens from morphological and physiological characteristics. FR252921, FR252922 and FR256523, novel compounds containing macrolactone ring, showed immunosuppressive activity against murine splenocyte proliferation stimulated with lipopolysaccharide (LPS) or anti-CD3 mAb in vitro. 相似文献