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排序方式: 共有1566条查询结果,搜索用时 343 毫秒
61.
目的:筛选当归活血的有效部位;探讨模糊物元模型在当归不同提取部位活血效果综合评价中的应用。方法:以皮下注射盐酸肾上腺素结合冰水浴建立急性大鼠血瘀模型,通过检测血液流变学及凝血4项[凝血酶原时间(PT),活化部分凝血活酶时间(APTT)和凝血酶时间(TT),纤维蛋白原含量(FIB)]指标,评价当归不同提取部位的活血效果;运用基于变异系数权重的模糊物元模型对活血的效果进行综合评价。结果:部位1~7均能降低大鼠全血黏度和血浆黏度,部位2能明显延长PT、TT时间(P<0.05)。反映活血总效应的最大贴进度值为0.527(70%乙醇浸渍部位)。结论:70%乙醇浸渍部位为当归活血的有效部位;基于变异系数权重的模糊物元模型可客观、准确地评价当归不同提取部位活血的综合效果。 相似文献
62.
A framework for testing the equality between the health concentration curve and the 45‐degree line 下载免费PDF全文
The health concentration curve is the standard graphical tool to depict socioeconomic health inequality in the literature on health inequality. This paper shows that testing for the absence of socioeconomic health inequality is equivalent to testing if the conditional expectation of health on income is a constant function that is equal to average health status. In consequence, any test for parametric specification of a regression function can be used to test for the absence of socioeconomic health inequality (subject to regularity conditions). Furthermore, this paper illustrates how to test for this equality using a test for parametric regression functional form and applies it to health‐related behaviors from the National Health Survey 2014. 相似文献
63.
Huakang Liang Shoujian Zhang Yikun Su 《International journal of occupational and environmental health》2018,24(1-2):61-74
The contractor-selection decision at the prequalification stage is critical to the project success. An insufficient prediction of contractors’ safety capacities using only lagging indicators may hinder the continuous improvement of safety performance in the construction industry. This research enhanced construction management and practices by proposing a comprehensive safe contractor selection model which integrated both leading and lagging indicators. First, a set of leading and lagging safety indicators were identified based on literature review and expert opinions. Then, the grey correlation analysis (GCA) was utilized to assign weights to individual indicators. We found that management commitment, safety training and education, safety risk management, and safety rules and procedures were four most influential factors to the safety performance of contractors. In addition, the fuzzy technique of ordering preference by similarity to ideal solution (Fuzzy TOPSIS) was used to condense individual indicators and create a composite safety performance indicator (c-SPI). Finally, the feasibility of the decision support tool for safe contractor selection was verified using a real-case railway construction project. 相似文献
64.
When assessing association between a binary trait and some covariates, the binary response may be subject to unidirectional misclassification. Unidirectional misclassification can occur when revealing a particular level of the trait is associated with a type of cost, such as a social desirability or financial cost. The feasibility of addressing misclassification is commonly obscured by model identification issues. The current paper attempts to study the efficacy of inference when the binary response variable is subject to unidirectional misclassification. From a theoretical perspective, we demonstrate that the key model parameters possess identifiability, except for the case with a single binary covariate. From a practical standpoint, the logistic model with quantitative covariates can be weakly identified, in the sense that the Fisher information matrix may be near singular. This can make learning some parameters difficult under certain parameter settings, even with quite large samples. In other cases, the stronger identification enables the model to provide more effective adjustment for unidirectional misclassification. An extension to the Poisson approximation of the binomial model reveals the identifiability of the Poisson and zero‐inflated Poisson models. For fully identified models, the proposed method adjusts for misclassification based on learning from data. For binary models where there is difficulty in identification, the method is useful for sensitivity analyses on the potential impact from unidirectional misclassification. 相似文献
65.
Chanmin Kim Michael Daniels Yisheng Li Kathrin Milbury Lorenzo Cohen 《Statistics in medicine》2018,37(7):1149-1161
In assessing causal mediation effects in randomized studies, a challenge is that the direct and indirect effects can vary across participants due to different measured and unmeasured characteristics. In that case, the population effect estimated from standard approaches implicitly averages over and does not estimate the heterogeneous direct and indirect effects. We propose a Bayesian semiparametric method to estimate heterogeneous direct and indirect effects via clusters, where the clusters are formed by both individual covariate profiles and individual effects due to unmeasured characteristics. These cluster‐specific direct and indirect effects can be estimated through a set of regression models where specific coefficients are clustered by a stick‐breaking prior. To let clustering be appropriately informed by individual direct and indirect effects, we specify a data‐dependent prior. We conduct simulation studies to assess performance of the proposed method compared to other methods. We use this approach to estimate heterogeneous causal direct and indirect effects of an expressive writing intervention for patients with renal cell carcinoma. 相似文献
66.
目的 采用孟德尔随机化(MR)方法探索睡眠性状与肠易激综合征(IBS)的因果关系。 方法 利用大规模全基因组关联研究汇总数据和芬兰生物银行数据(FinnGen),选择相互独立且与睡眠性状密切相关的遗传位点作为工具变量,通过逆方差加权法(MR-IVW)、加权中位数法、简单中位数法、稳健的调整轮廓评分法、MR多效性残差和与异质性法(MR-PRESSO)等MR方法,以比值比(OR值)作为评价指标对睡眠性状与IBS的因果关系进行探讨。 结果 MR-IVW结果显示,过短睡眠和失眠分别导致IBS发病风险增高147%(OR=2.47, 95%CI: 1.13~5.41 )和18%(OR=1.18, 95%CI: 1.14~1.22 ),早起型睡眠习惯会导致IBS发病风险降低12%(OR=0.88, 95%CI: 0.84~0.92 )。外部数据验证结果显示,仅失眠与IBS发病风险的关联有统计学意义(P<0.001)。多变量MR方法校正相关协变量后,失眠与IBS的关联效应仍有统计学意义(P<0.001)。 结论 过短睡眠和失眠会增加IBS的发病风险。 相似文献
67.
随着2020版《药品管理法》正式增设药品上市许可持有人(marketing authorization holder,MAH)制度、药品监管科学行动计划以及《关于结束中药配方颗粒试点工作的公告》的正式实施,标志着中药正式进入全生命周期监管时代。当前,我国尚未能建立起一个符合中药规律和发展特点的全生命周期中药监管体系,中药产品疗效不稳定,我国的中医药产品安全性和使用有效性难以取得国际市场的重视和认可。因此,迫切需要建立一套全生命周期的中药监管体系,加强对中药的科学监管来推动其高质量发展。结合我国中药全生命周期实际监管中存在的问题,提出研制、生产、流通、使用环节指标,构建科学的中药全生命周期监管的评价体系,采用基于模糊群决策的评价方法科学评价各因素,以期规范中药全生命周期监管,促进中药质量标准与国际接轨。 相似文献
68.
Raffaele Serra Umberto M. Bracale Andrea Barbetta Nicola Ielapi Noemi Licastro Alessandro Gallo Salvatore Fregola Davide Turchino Vincenzo Gasbarro Pasquale Mastroroberto Stefano de Franciscis 《International wound journal》2020,17(4):987-991
Peripheral arterial disease (PAD) and its most severe form, critical limb ischaemia (CLI), are very common clinical conditions related to atherosclerosis and represent the major causes of morbidity, mortality, disability, and reduced quality of life (QoL), especially for the onset of ischaemic chronic leg ulcers (ICLUs) and the subsequent need of amputation in affected patients. Early identification of patients at risk of developing ICLUs may represent the best form of prevention and appropriate management. In this study, we used a Prediction System for Chronic Leg Ulcers (PredyCLU) based on fuzzy logic applied to patients with PAD. The patient population consisted of 80 patients with PAD, of which 40 patients (30 males [75%] and 10 females [25%]; mean age 66.18 years; median age 67.50 years) had ICLUs and represented the case group. Forty patients (100%) (27 males [67.50%] and 13 females [32.50%]; mean age 66.43 years; median age 66.50 years) did not have ICLUs and represented the control group. In patients of the case group, the higher was the risk calculated with the PredyCLU the more severe were the clinical manifestations recorded. In this study, the PredyCLU algorithm was retrospectively applied on a multicentre population of 80 patients with PAD. The PredyCLU algorithm provided a reliable risk score for the risk of ICLUs in patients with PAD. 相似文献
69.
This article proposes a Fuzzy Second Order Integral Terminal Sliding Mode (FSOITSM) control approach for DFIG-based wind turbines subject to grid faults and parameter variations. Since traditional terminal sliding mode control (SMC) suffers from singularity, a novel integral terminal sliding manifold is proposed to eliminate chattering and improve the wind turbine's performance in the presence of faults and disturbances. A fuzzy system is proposed to auto-tune the controllers' gains and ensures the invariance of the sliding surfaces even under heavy uncertainties, thus further improving the reliability and performance of the proposed controller. The performance of the proposed approach was assessed under various operating conditions. A comparison analysis with a standard SMC approach as well as the state of the art in voltage sag mitigation was also carried over. Reliability, robustness, and power availability under faulty grid conditions are among the main features of the proposed approach. In addition, the proposed approach exhibited chattering free dynamics and enabled the finite time convergence of the sliding manifold and overcame the singularity problem associated with standard TSMC. 相似文献
70.
Yaen
Xie Yuehui Yan Zhen Shi Xiande Wu Hongtao Cui Zhidan Zhang 《Optimal control applications & methods.》2020,41(6):1995-2007
This paper aims to address the tracking control problem for the multi-joint manipulator on a space robot subject to model uncertainties and external disturbances. A Gauss-Newton interactive optimization algorithm is used to obtain the desired joint angle for each joint. In order to formulate the optimization problem, the Denaait-Hartenberg (D-H) method is employed to describe the model of the multi-joint manipulator. Subsequently, an adaptive controller is developed to achieve tracking control, where controller parameters updated in real time are introduced to handle the nondeterminacy of the multi-joint manipulator. Moreover, a fuzzy control strategy is composed such that our designed controller is robust against the complex environment as well. The controller design is performed by means of the Lyapunov techniques. Meanwhile, its effectiveness is verified through numerical simulations. Finally, some concluding remarks close the paper. 相似文献