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基于Null Importance分析慢病人群接受居家药学服务意愿的影响因素
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作者 赵科 杨宏昕 +2 位作者 武明芬 郭浩 赵志刚 《医药导报》 北大核心 2025年第8期1347-1351,共5页
目的探究慢病人群接受居家药学服务意愿的关键影响因素。方法采用中国适老化研究项目中内蒙古自治区及东北地区的调查数据,基于Null Importance方法,筛选影响慢病人群参与居家药学服务意愿的关键因素。构建logistic回归模型,采用5折交... 目的探究慢病人群接受居家药学服务意愿的关键影响因素。方法采用中国适老化研究项目中内蒙古自治区及东北地区的调查数据,基于Null Importance方法,筛选影响慢病人群参与居家药学服务意愿的关键因素。构建logistic回归模型,采用5折交叉验证方法,以准确率及AUC为指标,评价特征选择对模型性能的影响。结果Null Importance方法筛选出10个关键因素,且特征选择后logistic回归模型性能得到提升。显著影响患者对居家药学服务接受意愿的因素包括:获取药品信息途径个数(OR=1.261,95%CI=1.182~1.345),药物适应证认知(OR=1.342,95%CI=1.124~1.603),是否保留药盒(OR=1.218,95%CI=1.015~1.462),用药依从性得分(OR=0.881,95%CI=0.839~0.925),用药素养得分(OR=0.631,95%CI=0.488~0.817),用药指导服务了解程度(OR=1.211,95%CI=1.017~1.442)。结论在Null Importance特征选择方法基础上构建的logistic回归模型,具有良好的性能,有助于慢病人群接受居家药学服务意愿影响因素的分析。 展开更多
关键词 Null importance 居家药学服务 意愿 慢病
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Distribution,species richness,and relative importance of different plant life forms across drylands in China 被引量:1
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作者 Shuran Yao Weigang Hu +16 位作者 Mingfei Ji Abraham Allan Degen Qiajun Du Muhammad Adnan Akram Yuan Sun Ying Sun Yan Deng Longwei Dong Haiyang Gong Qingqing Hou Shubin Xie Xiaoting Wang Jinzhi Ran Bernhard Schmid Qinfeng Guo Karl J.Niklas Jianming Deng 《Plant Diversity》 2025年第2期273-281,共9页
Studies on plant diversity are usually based on the total number of species in a community.However,few studies have examined species richness(SR)of different plant life forms in a community along largescale environmen... Studies on plant diversity are usually based on the total number of species in a community.However,few studies have examined species richness(SR)of different plant life forms in a community along largescale environmental gradients.Particularly,the relative importance(RIV)of different plant life forms in a community and how they vary with environmental variables are still unclear.To fill these gaps,we determined plant diversity of ephemeral plants,annual herbs,perennial herbs,and woody plants from 187 sites across drylands in China.The SR patterns of herbaceous plants,especially perennial herbs,and their RIV in plant communities increased with increasing precipitation and soil nutrient content;however,the RIV of annual herbs was not altered along these gradients.The SR and RIV of ephemeral plants were affected mainly by precipitation seasonality.The SR of woody plants had a unimodal relationship with air temperature and exhibited the highest RIV and SR percentage in plant communities under the harshest environments.An obvious shift emerged in plant community composition,SR and their critical impact factors at 238.5 mm of mean annual precipitation(MAP).In mesic regions(>238.5 mm),herbs were the dominant species,and the SR displayed a relatively slow decreasing rate with increasing aridity,which was mediated mainly by MAP and soil nutrients.In arid regions(<238.5 mm),woody plants were the dominant species,and the SR displayed a relatively fast decreasing rate with increasing aridity,which was mediated mainly by climate variables,especially precipitation.Our findings highlight the importance of comparative life form studies in community structure and biodiversity,as their responses to gradients differed substantially on a large scale. 展开更多
关键词 DRYLANDS Environmental gradients Plant life forms Relative importance Species richness THRESHOLD
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Analysis of Influencing Factors of Academic Warning in Higher Vocational Colleges Based on the Importance of Machine Learning Features and Paths to Improve Learning Ability 被引量:1
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作者 Meimei Huang Lei Zhang Xifeng Fan 《Journal of Contemporary Educational Research》 2025年第5期75-80,共6页
The traditional academic warning methods for students in higher vocational colleges are relatively backward,single,and have many influencing factors,which have a limited effect on improving their learning ability.A da... The traditional academic warning methods for students in higher vocational colleges are relatively backward,single,and have many influencing factors,which have a limited effect on improving their learning ability.A data set was established by collecting academic warning data of students in a certain university.The importance of the school,major,grade,and warning level for the students was analyzed using the Pearson correlation coefficient,random forest variable importance,and permutation importance.It was found that the characteristic of the major has a great impact on the academic warning level.Countermeasures such as dynamic adjustment of majors,reform of cognitive adaptation of courses,full-cycle academic support,and data-driven precise intervention were proposed to provide theoretical support and practical paths for universities to improve the efficiency of academic warning and enhance students’learning ability. 展开更多
关键词 Academic warning Pearson correlation coefficient Random forest variable importance Permutation importance
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Role of feature importance in geomechanical classification of rock slopes
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作者 Ashutosh Kainthola Vishnu Himanshu Ratnam Pandey +1 位作者 Gaurav Kushwaha Vikas Yadav 《Deep Resources Engineering》 2025年第1期9-24,共16页
Rock slope along motorways in the Higher Himalayan terrains are prone to various types of failure.In order to effectively mitigate these failures,a thorough assessment of rock mass behavior is entailed.The present res... Rock slope along motorways in the Higher Himalayan terrains are prone to various types of failure.In order to effectively mitigate these failures,a thorough assessment of rock mass behavior is entailed.The present research employs and compares widely practiced geo-mechanical classification schemes viz.,RQD,RMR,SMR,Q-slope,and GSI.A 23 km road cut section,along Sangla to Chitkul route,in Higher Himalayan region(India)has been taken up for this work.Total of 18 locations were selected,and their slope and rockmass properties were examined.Afterwards,the most influencing parameters in RMR,SMR,and Q-Slope were evaluated through a machine learning algorithm,i.e.,Random Forest.For RMRbasic,about 83%of rock-slopes were designated in good condition and rest were of Fair quality.Evaluation of slope mass rating along all 18-locations highlighted eight-sites as partially unstable,six-sites as partially stable.Remaining four locations varied between,Very Bad to Bad slope-conditions,necessitating the installation of mechanical supports and redesign of slopes.For SMR classification,feature importance analysis revealed the predominance of F3 variable,RQD and intact rock strength.Q-Slope approach was incorporated to identify the most stable steepest angle of the examined locations.For Q-Slope rating,Jn and RQD were found to have the most influence in classification of the slopes.Three zones on the basis of GSI-scores have been identified in the study area,i.e.,A(6595),B(4555),and C(2535).This study highlights the application of multiple geomechanical classification schemes,demonstrating how each approach can complement the others. 展开更多
关键词 SMR Q-slope GSI Feature importance Partial dependence Economic Mitigations
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Corrigendum to“Meta databases of steel frame buildings for surrogate modelling and machine learning-based feature importance analysis”[Journal of Resilient Cities and Structures Volume 3 Issue 1(2024)20-43]
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作者 Delbaz Samadian Jawad Fayaz +2 位作者 Imrose B.Muhit Annalisa Occhipinti Nashwan Dawood 《Resilient Cities and Structures》 2025年第1期124-124,共1页
The authors regret that the original publication of this paper did not include Jawad Fayaz as a co-author.After further discussions and a thorough review of the research contributions,it was agreed that his significan... The authors regret that the original publication of this paper did not include Jawad Fayaz as a co-author.After further discussions and a thorough review of the research contributions,it was agreed that his significant contributions to the foundational aspects of the research warranted recognition,and he has now been added as a co-author. 展开更多
关键词 machine learning meta databases jawad fayaz surrogate modelling feature importance analysis steel frame buildings
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Unveiling hidden biases in machine learning feature importance
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作者 Yoshiyasu Takefuji 《Journal of Energy Chemistry》 2025年第3期49-51,共3页
Nirmal et al.presented a machine learning-based design of ternary organic solar cells,utilizing feature importance[1].This paper highlights the alarming potential biases in the use of feature importance in machine lea... Nirmal et al.presented a machine learning-based design of ternary organic solar cells,utilizing feature importance[1].This paper highlights the alarming potential biases in the use of feature importance in machine learning,which can lead to incorrect conclusions and outcomes.Many scientists and researchers including Nirmal et al.are unaware that feature importances in machine learning in general are model-specific and do not necessarily represent true associations between the target and features. 展开更多
关键词 Machine learning Feature importance Potential bias Chi-squared and P-value
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Moderate Deviations for the Optimal Values of Sample Average Approximation with Adaptive Multiple Importance Sampling
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作者 Wenjin ZHANG 《Journal of Mathematical Research with Applications》 2025年第2期275-284,共10页
In this paper, we use sample average approximation with adaptive multiple importance sampling to explore moderate deviations for the optimal values. Utilizing the moderate deviation principle for martingale difference... In this paper, we use sample average approximation with adaptive multiple importance sampling to explore moderate deviations for the optimal values. Utilizing the moderate deviation principle for martingale differences and an appropriate Delta method, we establish a moderate deviation principle for the optimal value. Moreover, for a functional form of stochastic programming, we obtain a functional moderate deviation principle for its optimal value. 展开更多
关键词 adaptive multiple importance sampling martingale difference moderate deviation
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Stress signaling caused by mitochondrial import malfunction can be terminated by SIFI:Importance of stress response silencing
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作者 Grace Hohman Michael Shahid Mohamed A.Eldeeb 《Neural Regeneration Research》 2026年第2期673-674,共2页
Protein aggregates,mitochondrial import stress and neurodegenerative disorders:A salient hallmark of several neurodegenerative diseases,including Parkinson’s disease,is the abundance of protein aggregates(Goiran et a... Protein aggregates,mitochondrial import stress and neurodegenerative disorders:A salient hallmark of several neurodegenerative diseases,including Parkinson’s disease,is the abundance of protein aggregates(Goiran et al.,2022).This molecular event is believed to lead to activation of stress pathways ultimately resulting in cellular dysfunction(Eldeeb et al.,2022).Accordingly,many lines of research investigations focused on dampening the formation of protein aggregates or augmenting the clearance of protein aggregates as a potential therapeutic strategy to counteract the progression of neurodegenerative diseases,albeit with little success(Costa-Mattioli and Walter,2020).Cell stress cues such as the accumulation of protein aggregates lead to the activation of stress response pathways that aid cells in responding to the damage.Despite the notion that the transient activation of these pathways helps cells cope with stressors,persistent activation can induce unwanted apoptosis of cells and reduce overall tissue strength as well as lead to an accumulation of aggregation-prone proteins(Hetz and Papa,2018).Mutations in proteins involved in stress signaling termination can cause conditions like ataxia and early-onset dementia(Conroy et al.,2014).Therefore,it is crucial for stress response signaling to be turned off once conditions have improved.Nevertheless,the mechanisms by which cells silence these signals are still elusive. 展开更多
关键词 activation stress pathways neurodegenerative disorders protein aggregatesmitochondrial import stress stress signaling protein aggregates goiran protein aggregates protein aggr neurodegenerative diseasesincluding
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Research on a Monte Carlo global variance reduction method based on an automatic importance sampling method 被引量:2
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作者 Yi-Sheng Hao Zhen Wu +3 位作者 Shen-Shen Gao Rui Qiu Hui Zhang Jun-Li Li 《Nuclear Science and Techniques》 SCIE EI CAS CSCD 2024年第5期200-215,共16页
Global variance reduction is a bottleneck in Monte Carlo shielding calculations.The global variance reduction problem requires that the statistical error of the entire space is uniform.This study proposed a grid-AIS m... Global variance reduction is a bottleneck in Monte Carlo shielding calculations.The global variance reduction problem requires that the statistical error of the entire space is uniform.This study proposed a grid-AIS method for the global variance reduction problem based on the AIS method,which was implemented in the Monte Carlo program MCShield.The proposed method was validated using the VENUS-Ⅲ international benchmark problem and a self-shielding calculation example.The results from the VENUS-Ⅲ benchmark problem showed that the grid-AIS method achieved a significant reduction in the variance of the statistical errors of the MESH grids,decreasing from 1.08×10^(-2) to 3.84×10^(-3),representing a 64.00% reduction.This demonstrates that the grid-AIS method is effective in addressing global issues.The results of the selfshielding calculation demonstrate that the grid-AIS method produced accurate computational results.Moreover,the grid-AIS method exhibited a computational efficiency approximately one order of magnitude higher than that of the AIS method and approximately two orders of magnitude higher than that of the conventional Monte Carlo method. 展开更多
关键词 Monte Carlo Global variance reduction Reactor shielding Automatic importance sampling
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基于Null Importance和Stacking模型的知识追踪研究 被引量:1
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作者 梁开迪 张丽华 《中国科技论文在线精品论文》 2024年第2期174-182,共9页
为应对基于游戏的学习平台在知识追踪应用方面的不足,本研究利用Field Day Lab提供的教育游戏用户日志进行深入分析。采用方差法和Null Importance方法对数据集进行降维处理,并结合K折交叉验证与LightGBM算法,建立了一个高效的预测模型... 为应对基于游戏的学习平台在知识追踪应用方面的不足,本研究利用Field Day Lab提供的教育游戏用户日志进行深入分析。采用方差法和Null Importance方法对数据集进行降维处理,并结合K折交叉验证与LightGBM算法,建立了一个高效的预测模型。此外,通过集成Logistic模型,构建起Stacking模型。研究表明,该模型在验证集上的Macro-F1值显著提升至0.699,同时也在测试集上显示出优异的泛化能力。本研究为教育游戏领域的知识追踪提供了创新方法,并为游戏开发与教育实践提供了宝贵参考,支持教育游戏的开发者为学生创造更有效的学习体验。 展开更多
关键词 人工智能 知识追踪 Null importance Stacking集成模型
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Component uncertainty importance measure in complex multi-state system considering epistemic uncertainties
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作者 Rentong CHEN Shaoping WANG +4 位作者 Chao ZHANG Hongyan DUI Yuwei ZHANG Yadong ZHANG Yang LI 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2024年第12期31-54,共24页
Importance measures can be used to identify the vulnerable components in an aviation system at the early design stage.However,due to lack of knowledge or less available information on the component or system,the epist... Importance measures can be used to identify the vulnerable components in an aviation system at the early design stage.However,due to lack of knowledge or less available information on the component or system,the epistemic uncertainties may be one of the challenging issues in importance evaluation.In addition,the properties of the aircraft system,which are the fundamentals of the component importance measure,including the hierarchy,dependency,randomness,and uncertainty,should be taken into consideration.To solve these problems,this paper proposes the component Uncertainty Integrated Importance Measure(component UIIM)which considers multiple epistemic uncertainties in the complex multi-state systems.The degradation process for the components is described by a Markov model,and the system reliability model is developed using the Markov hierarchal evidential network.The concept of integrated importance measure is then extended into component UIIM to evaluate the component criticality rather than the component state change criticality,from the perspective of system performance.A case study on displacement compensation hydraulic system is presented to show the effectiveness of the proposed uncertainty importance measure.The results show that the component UIIM can be an effective method for evaluating the component criticality from system performance perspective at the system early design. 展开更多
关键词 importance measure Epistemic uncertainty Multi-state system Evidence theory Markov hierarchal evidential network
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Development of endemicity and conservation importance indices for tropical forests and the floral diversity assessment of Mt.Natoo in Benguet,Philippines
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作者 Johndale Rein T.BULLONG Jim P.SILVERIO +2 位作者 Joanna I.ALAFAG Maricel A.GURON Jones T.NAPALDET 《Journal of Mountain Science》 SCIE CSCD 2024年第3期786-804,共19页
The scientific community faces the challenge of measuring progress toward biodiversity targets and indices have been traditionally used.However,recent inventories in secondary tropical mountain forests using tradition... The scientific community faces the challenge of measuring progress toward biodiversity targets and indices have been traditionally used.However,recent inventories in secondary tropical mountain forests using traditional biodiversity indices have yielded results that are indistinct with primary ones.This shows the need to develop complementary indices that goes beyond species count but integrates the distribution and conservation status of the species.This study developed endemicity and conservation importance index for tropical forest that incorporated the distribution and conservation status of the species.These indices were applied to Mt.Natoo,a remnant primary mossy forest in Buguias,Benguet,Philippines,that resulted to endemicity index of 81.07 and conservation importance index of 42.90.Comparing these with secondary forest sites with comparable Shannon-Wiener,Simpson,Evenness and Margalef’s indices,our endemicity and conservation indices clearly differentiates primary forest(our study site)with higher values from secondary forests with much lower values.Thus,we are proposing these indices for a direct but scientifically-informed identification of specific sites for conservation and protection in tropical forests.Additionally,our study documented a total of 168 vascular plant species(79 endemic and 12 locally threatened species)in Mt.Nato-o.Majority are of tropical elements for both generic and species levels with some temperate elements that could be attributed to the site's high elevation and semi-temperate climate.These are important baseline information for conservation plans and monitoring of tropical mossy forests. 展开更多
关键词 Endemicity index Conservation importance index Cordillera Central Range Floristic element Jaccard Index of Similarity
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Importance-Weighted Transfer Learning for Fault Classification under Covariate Shift
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作者 Yi Pan Lei Xie Hongye Su 《Intelligent Automation & Soft Computing》 2024年第4期683-696,共14页
In the process of fault detection and classification,the operation mode usually drifts over time,which brings great challenges to the algorithms.Because traditional machine learning based fault classification cannot d... In the process of fault detection and classification,the operation mode usually drifts over time,which brings great challenges to the algorithms.Because traditional machine learning based fault classification cannot dynamically update the trained model according to the probability distribution of the testing dataset,the accuracy of these traditional methods usually drops significantly in the case of covariate shift.In this paper,an importance-weighted transfer learning method is proposed for fault classification in the nonlinear multi-mode industrial process.It effectively alters the drift between the training and testing dataset.Firstly,the mutual information method is utilized to perform feature selection on the original data,and a number of characteristic parameters associated with fault classification are selected according to their mutual information.Then,the importance-weighted least-squares probabilistic classifier(IWLSPC)is utilized for binary fault detection and multi-fault classification in covariate shift.Finally,the Tennessee Eastman(TE)benchmark is carried out to confirm the effectiveness of the proposed method.The experimental result shows that the covariate shift adaptation based on importance-weight sampling is superior to the traditional machine learning fault classification algorithms.Moreover,IWLSPC can not only be used for binary fault classification,but also can be applied to the multi-classification target in the process of fault diagnosis. 展开更多
关键词 Covariate shift adaption nonlinear multi-mode process importance weight sampling multi-fault classification
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The Importance of Breathing Training in Folk Dance Teaching
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作者 Xiaowei Sun 《Journal of Contemporary Educational Research》 2024年第4期187-192,共6页
The importance of breathing training in dance teaching is reflected in the two aspects of enhancing the quality of dance movements and sublimating the connotation of dance movements.For example,high-quality breathing ... The importance of breathing training in dance teaching is reflected in the two aspects of enhancing the quality of dance movements and sublimating the connotation of dance movements.For example,high-quality breathing can help performers complete the dance movements and improve the coordination of the movements;at the same time,the unique body rhythm formed by breathing can strengthen the visual effect of the performance and convey its spirit and soul to the audience.This requires folk dance teachers to carry out relevant training and teaching activities based on the categories and skills of dance breathing,such as changing students’ideological cognition,developing periodic breathing training courses,providing personalized guidance to students,and allowing students to adjust their learning and practice methods in the evaluation. 展开更多
关键词 Folk dance teaching Breathing training importance Training methods
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武汉市1例输入性黑热病的诊断及调查分析 被引量:1
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作者 杨燕 周水茂 +6 位作者 郭庆 张娟 贾西帅 罗华堂 王帅 刘聪 徐文秀 《中国热带医学》 北大核心 2025年第1期127-130,共4页
报道武汉市1例输入性黑热病确诊病例的发现、诊断、治疗及流行病学调查,为提高非流行区医疗卫生机构专业人员对输入性黑热病的认识,减少误诊提供参考经验。患者在山西阳泉务工1年余;2020年返回湖北家乡后开始陆续出现间断发热、全血细... 报道武汉市1例输入性黑热病确诊病例的发现、诊断、治疗及流行病学调查,为提高非流行区医疗卫生机构专业人员对输入性黑热病的认识,减少误诊提供参考经验。患者在山西阳泉务工1年余;2020年返回湖北家乡后开始陆续出现间断发热、全血细胞性贫血、脾脏进行性肿大以及体质量减轻等症状。经骨髓涂片查见利什曼原虫无鞭毛体,rk39快速检测试纸条法检测抗体阳性,环介导等温扩增法(LAMP)和实时荧光定量PCR法(qPCR)核酸检测利什曼原虫阳性。根据流行病学史、临床表现和实验室检查结果,确定为输入性黑热病确诊病例。该病例原虫密度低,伴有类风湿因子增高等自身免疫指标异常,长期被误诊为血液系统、自身免疫系统疾病,未得到有效治疗,离开流行区4年后才得以确诊。建议黑热病非流行区应重视流行病学史的询问,提高医疗卫生机构的诊断意识和诊疗水平,避免延误治疗。 展开更多
关键词 黑热病 利什曼原虫 输入性病例 误诊
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中缅边境地区消除疟疾策略与疟疾联防联控合作探讨 被引量:2
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作者 魏春 林祖锐 +3 位作者 杨中华 周红宁 周兴武 杨锐 《中国血吸虫病防治杂志(中英文)》 北大核心 2025年第1期19-23,54,共6页
云南省与缅甸、越南、老挝3国接壤,中缅边境地区是我国消除疟疾后防止疟疾输入再传播的重点地区。云南省自2011年起全面启动消除疟疾行动计划,按照疟疾发病率和传播风险将全省129个县(市、区)划分为3类,采取不同的疟疾防治技术策略和措... 云南省与缅甸、越南、老挝3国接壤,中缅边境地区是我国消除疟疾后防止疟疾输入再传播的重点地区。云南省自2011年起全面启动消除疟疾行动计划,按照疟疾发病率和传播风险将全省129个县(市、区)划分为3类,采取不同的疟疾防治技术策略和措施。2014年,云南省在中方边境建立了68个疟疾咨询服务站、在缅甸边境地区设置了80个疟疾防治服务站。2015—2018年,云南省在中缅边境地区实施消除疟疾“三道防线”措施;2019年,对该措施进一步调整和细化,形成了防止疟疾输入再传播的“3+1”策略。经过多年努力,2021年6月云南省实现了消除疟疾目标。但受缅甸局势变化以及我国调整新型冠状病毒感染疫情防控政策后国际旅行和口岸通关逐步恢复等因素影响,2023年和2024年云南省输入性疟疾病例数呈上升趋势。我国与缅甸疟疾联防联控合作始于2005年的“中缅边境地区疟疾联防联控试点项目”;2010年,该项目发展为“大湄公河次区域部分边境地区疟疾和登革热联防联控项目”。通过与缅甸卫生部门举办协调会、畅通信息互通机制、建立境外监测哨点、开展技术培训、提供物资支持、开展联合宣传和联合疫情处置等措施,有效降低了境外疟疾疫情对云南省边境地区的威胁。2018年,该项目纳入国家《澜沧江-湄公河合作五年行动计划(2018—2022)》,与缅甸、老挝、越南、柬埔寨和泰国建立了5个联络办公室和20个联络工作站,在缅甸、老挝和越南边境地区建立了21个跨境疟疾监测哨点,每年通过会议、培训、宣传、联合调查等多种形式建立了疟疾防控长期合作机制。目前,云南省在国家《澜沧江-湄公河合作五年行动计划(2023—2027)》指引下,将与周边国家在疟疾防控诊疗技术、药物与疫苗研发、人才培养、信息共享、跨境人群健康服务和健康促进等方面开展更广泛和深入的合作。 展开更多
关键词 输入性疟疾 消除 联防联控 中缅边境 云南省
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华北落叶松人工林林下物种多样性特征研究 被引量:4
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作者 康义 辛学兵 +5 位作者 裴顺祥 郭慧 法蕾 吴莎 马淑敏 吴迪 《西北林学院学报》 北大核心 2025年第1期23-31,82,共10页
对河北省塞罕坝第三乡林场不同营林区的华北落叶松人工林林下物种多样性进行调查,对比分析不同营林区内林下植被组成及灌木层和草本层的物种重要值、结构特征和物种多样性指数(物种丰富度指数、Simpson优势度指数、Shannon-Wiener多样... 对河北省塞罕坝第三乡林场不同营林区的华北落叶松人工林林下物种多样性进行调查,对比分析不同营林区内林下植被组成及灌木层和草本层的物种重要值、结构特征和物种多样性指数(物种丰富度指数、Simpson优势度指数、Shannon-Wiener多样性指数和Pielou均匀度指数),探究林下植被物种重要值及多样性指数在3个营林区内的变化差异。结果表明,3个营林区内华北落叶松人工林林下植物共116种,隶属44科86属。林下植物的科、属、种总数在3个营林区中表现一致,即母子沟最高,莫里莫次之,北岔最低。灌木层优势科均以蔷薇科居多,草本层优势科则各有不同,显示出明显的地区差异性。莫里莫营林区灌草层的指数值高于其他2个营林区,母子沟居中,北岔最低。莫里莫营林区高灌草层多样性测度指数可能反映该地区生态系统的较高健康度和韧性,而母子沟的中等多样性测度指数可能表明其生态系统正处于过渡状态,北岔营林区的低多样性测度指数暗示生态系统可能面临潜在风险。研究结果对第三乡林场不同营林区内华北落叶松人工林生态系统的健康管理提供了数据支撑。 展开更多
关键词 华北落叶松人工林 物种多样性 物种重要值 林下植物 塞罕坝
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中国大豆进口市场布局多目标优化策略研究 被引量:2
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作者 葛明 刘向昱 高远东 《农业经济问题》 北大核心 2025年第2期126-144,共19页
本文构建“风险最小—成本最低—质量最高”多目标模型探究了中国大豆进口市场布局优化策略及其效果,采用结构分解模型识别了优化效果贡献源,并模拟了潜在冲击的影响。结果显示:中国大豆进口风险、成本、质量变动趋势存在显著的国别差... 本文构建“风险最小—成本最低—质量最高”多目标模型探究了中国大豆进口市场布局优化策略及其效果,采用结构分解模型识别了优化效果贡献源,并模拟了潜在冲击的影响。结果显示:中国大豆进口风险、成本、质量变动趋势存在显著的国别差异性和动态不一致性,当前市场布局存在较大的优化空间,以巴西和美国市场份额调整为主,且两者存在此起彼伏的关系,优化后的市场布局既降低了综合风险,也减少平均成本,还提升了产品质量,其中风险降低的效果尤为明显,这主要归因于市场集中度下降的影响。进一步研究发现,中美政治风险上升、国内进口需求增长、巴西对华出口潜力下降均导致我国大豆进口平均成本上升和综合质量下降,且前两者还提高了综合风险。因此,中国应积极优化市场布局、稳定大国经贸关系、提高国产规模与质量、健全风险预警防控体系以保障大豆进口供应链安全、经济与高质量发展。 展开更多
关键词 大豆 进口风险 市场布局 多目标优化 NSGA算法
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中国中间品进口供应链韧性:演进趋势、影响因素及发展对策 被引量:1
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作者 项松林 苏立平 《财经问题研究》 北大核心 2025年第2期80-91,共12页
在特朗普2.0时代,提升中间品进口供应链韧性对于保障中国经济安全、促进国内国际双循环具有重要的现实意义。本文区分了全球供应集中度和进口来源集中度,构建了一个可用于分析中间品进口供应链韧性的基本框架,利用CEPII BACI数据库的基... 在特朗普2.0时代,提升中间品进口供应链韧性对于保障中国经济安全、促进国内国际双循环具有重要的现实意义。本文区分了全球供应集中度和进口来源集中度,构建了一个可用于分析中间品进口供应链韧性的基本框架,利用CEPII BACI数据库的基础数据实际测算了1995—2022年中国中间品进口供应链韧性,并进一步分析了中国中间品进口供应链韧性的影响因素。研究结论如下:从演进趋势来看,1995—2022年,中国中间品进口供应链韧性逐渐提升,总体处于安全范畴,但极易受外部冲击影响。从影响因素来看,中国进口供应链韧性的主要影响因素为进口来源集中度。近年来,该因素对中国中间品供应链韧性的提升作用有所降低。“一带一路”倡议为稳定中国中间品进口供应链韧性作出积极贡献。西方发达国家极限施压的负面影响不容小觑。因此,应采取差异化政策,提升中间品进口供应链韧性;深挖潜力,努力从内部寻找替中间品;争取最大可能地与西方发达国家开展产业合作;加大国际合作力度,持续拓展进口中间品的全球来源;强化新质生产力的赋能作用,提升中间品供应链韧性。本文的研究有助于客观评估中国中间品进口供应链韧性,并为提升产业链供应链韧性提供决策参考。 展开更多
关键词 中间品进口 供应链韧性 进口来源集中度 全球供应集中度
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中国钨矿的矿床类型划分、空间分布和开发利用现状 被引量:2
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作者 余金杰 杨郧城 +3 位作者 陈其慎 陈绍聪 陈小丹 张蕊 《地球学报》 北大核心 2025年第5期945-953,共9页
我国钨矿床类型主要有斑岩型钨矿、矽卡岩型钨矿、云英岩型钨矿、石英脉型钨矿、蚀变花岗岩型钨矿、砂钨矿和其他类型钨矿。其中,矽卡岩型钨矿和石英脉型钨矿是主要矿床类型。本文编制了中国钨矿空间分布及开发利用现状图,共划分出13个... 我国钨矿床类型主要有斑岩型钨矿、矽卡岩型钨矿、云英岩型钨矿、石英脉型钨矿、蚀变花岗岩型钨矿、砂钨矿和其他类型钨矿。其中,矽卡岩型钨矿和石英脉型钨矿是主要矿床类型。本文编制了中国钨矿空间分布及开发利用现状图,共划分出13个成钨区带。我国钨矿具有广泛展布且局部集中的特点,大中型矿区及白钨矿矿石类型资源储量占主导。我国钨矿床共(伴)生组分多、综合利用价值大,但富矿少、贫矿多。钨矿是我国优势的矿产资源,我国是世界上最大的钨生产国和供应国,钨年产量占世界年产量的81%。我国钨产业链覆盖完整,前端和中端具有明显优势,高性能、高精度的高档硬质合金仍依赖国外进口。 展开更多
关键词 矿床类型 空间分布规律 利用现状 进出口 钨矿床
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