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某电机齿轮冷挤压裂纹形成机理研究

塑性工程学报 2024年第8期31卷 208-215页

作者：董文正王丹林启权刘鲜蓉许小龙湘潭大学机械工程与力学学院湖南湘潭411105 中南大学极端服役性能精准制造国家重点实验室湖南长沙410083 玉环普天单向器有限公司浙江玉环317600

针对材料为20Cr的某电机齿轮在冷挤压成形时内齿齿顶面上出现的裂纹缺陷,基于DEFORM-3D对其冷挤压过程进行了模拟,研究了其裂纹形成机理。有限元结果表明,内齿的金属流动速度小于中部及下部外齿的流动速度,内齿齿顶面上齿根处的金属流... 详细信息

针对材料为20Cr的某电机齿轮在冷挤压成形时内齿齿顶面上出现的裂纹缺陷,基于DEFORM-3D对其冷挤压过程进行了模拟,研究了其裂纹形成机理。有限元结果表明,内齿的金属流动速度小于中部及下部外齿的流动速度,内齿齿顶面上齿根处的金属流动速度最小,此处流动最不均匀,易产生应力集中;对齿面的最大主应力及损伤分布进行了分析,得出在内齿齿顶面上,中部及距离下端面1 mm左右的位置应力集中最明显,拉应力较大且大于材料抗拉强度,损伤值也较大且大于临界损伤值,会产生裂纹,与实际情况相符合。通过改变凹模入模角来控制成形缺陷情况,当凹模入模角为23°时,齿根处拉应力下降,损伤值减小,投入生产后次品率从原本的50%降为1%。

关键词：冷挤压齿轮裂纹缺陷模具优化韧性断裂损伤

臭氧催化/超滤组合工艺去除石化反渗透浓水中有机物

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水处理技术 2024年第5期50卷 113-118页

作者：祁琳仲慧赟刘绍山陈云亮董良飞常州大学环境科学与工程学院常州大学城市建设学院江苏智芯今创科技有限公司江苏常州213164

由于石化反渗透浓水含盐量高且存在难降解有机物,不利于水资源的回收利用。采用臭氧催化/超滤组合工艺去除反渗透浓水中的有机物,通过分析臭氧催化氧化预处理实验中影响因素并考察超滤膜比通量变化规律并结合膜污染动力学模型揭示膜污... 详细信息

由于石化反渗透浓水含盐量高且存在难降解有机物,不利于水资源的回收利用。采用臭氧催化/超滤组合工艺去除反渗透浓水中的有机物,通过分析臭氧催化氧化预处理实验中影响因素并考察超滤膜比通量变化规律并结合膜污染动力学模型揭示膜污染机理。研究结果表明:当臭氧催化氧化预处理条件为臭氧浓度17 mg/L、催化剂投加量体积比40%、紫外光强0.7 mW/cm^(2)、反应时间40 min,臭氧催化氧化预处理效果最佳;探讨孔径、流速、温度对膜比通量及膜污染影响,得出最佳运行条件为孔径20 nm、流速4.2 L/min、温度40℃且孔径越大、温度越低、流速越小,膜比通量越小,膜污染越严重;基于三维荧光光谱(3D-EEM)及水质分析,臭氧催化/超滤组合工艺能高效去除石化反渗透浓水中有机物。本研究构建的组合工艺可为石化反渗透浓水中的有机物去除提供参考。

关键词：石化反渗透浓水有机物臭氧催化超滤

Myocardial ischemic changes of electrocardiogram in intracerebral hemorrhage: A case report and review of literature

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World Journal of Clinical Cases 2019年第21期7卷 3603-3614页

作者： Xue-qi lin Liang-Rong Zheng Department of Cardiovascular The First Affiliated Hospital of Zhejiang University

BACKGROUND Cardiac injury may occur after acute pathology of central nervous system(CNS)without any evidence of primary cardiac *** resulting structural and/or functional changes are called cerebrocardiac syndrome(CCS).The great majority of studies have been performed in patients with subarachnoid hemorrhage(SAH),while CCS data after intracerebral hemorrhage(ICH)are *** may cause diagnostic and therapeutic pitfalls for the clinician due to a lack of specific clinical manifestations and diagnostic *** the underlying pathophysiological and molecular mechanism(s)following cerebrovascular incidents will help to implement prevention and treatment strategies to improve the *** SUMMARY A 37-year-old man with a history of hypertension presented to our department on an emergency basis because of a sudden dizziness and left limb *** computed tomography(CT)suggested ICH in the occipital and parietal lobes,and the chosen emergency treatment was hematoma *** ventricular(LV)dysfunction occurred after the next 48 h and the electrocardiogram(ECG)showed non-ST elevation myocardial *** was suspected first in the context of ICH due to the negative result of the coronary CT *** Misinterpretation of ischemic-like ECGs may lead to unnecessary or hazardous interventions and cause undue delay of rehabilitation after *** objective is to highlight the clinical implications of CCS and we hope the differential diagnoses will be considered in patients with acute CNS diseases.

关键词： Stroke Intracerebral hemorrhage Cerebrocardiac syndrome Cardiac insufficiency Non-ST elevation myocardial infraction Case report Neurogenic stunned myocardium

Iron-catalyzed transformations of diazo compounds

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National Science Review 2014年第4期1卷 580-603页

作者： Shou-Fei Zhu qi-lin Zhou State Key Laboratory and Institute of Elemento-Organic Chemistry Nankai University Collaborative Innovation Center of Chemical Science and Engineering (Tianjin)

Although iron-promoted diazo transformations were only discovered during the 1990s,iron can undergo facile changes in its oxidation state and possesses distinct Lewis acid character,and these properties have aforded iron a privileged position as a catalyst in the transformations of diazo *** this review,we have provided an overview of the iron-catalyzed diazo transformation reactions reported in the literature by the end of 2013 with the aim of stimulating further interest in this area of research.

关键词： iron catalysis diazo compounds synthesis

Catalyst-free Multicomponent Synthesis of β-Mercapto Diketones in Water

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Chinese Journal of Chemistry 2011年第9期29卷 1856-1862页

作者： Li, Li Liu, Bokai WU, qi lin, Xianfu Department of Chemistry Zhejiang University Hangzhou Zhejiang 310027 China

A simple, efficient and eco-friendly route has been developed for the synthesis of fl-mercapto diketones via a multicomponent reaction of an aldehyde, acetylacetone and thiol in water. This methodology affords a numbe... 详细信息

关键词： catalyst-free multicomponent reaction β-mercapto diketone water chemistry thiol

维持性血液透析患者血清25羟维生素D水平与握力和捏力的相关性分析

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中国血液净化 2024年第6期23卷 436-440页

作者：杨亚奇刘琳林绮婷刘云谭荣韶刘岩贵州医科大学临床医学院贵阳550004 茂名市人民医院肾内科茂名525099 暨南大学附属广州红十字会医院肾内科病态营养研究所广州510220

目的探讨维持性血液透析(maintenance hemodialysis,MHD)患者血清25羟维生素D[25(OH)D]水平与握力(handgrip strength,HGS)和捏力(pinch strength,PS)的关系。方法采用单中心横断面研究,纳入2021年3月暨南大学附属广州红十字会医院血液净化中心行规律MHD的患者,收集受试者的一般资料,透析前测定血常规、血清生化指标和25(OH)D水平(电化学发光免疫法),使用测力计测量HGS和PS水平。根据25(OH)D水平将受试者分为25(OH)D正常组[25(OH)D>30 ng/ml]、25(OH)D不足组[20 ng/ml≤25(OH)D≤30 ng/ml]、25(OH)D缺乏组[25(OH)D<20 ng/ml],比较3组间各指标的差异。应用Spearman相关分析和线性回归评价25(OH)D水平与HGS和PS的相关性。结果共纳入126例MHD患者,25(OH)D正常组28例(22.22%)、不足组42例(33.33%)、缺乏组56例(44.44%)。Spearman相关性分析提示血清25(OH)D水平与HGS(r=0.289,P=0.001)、PS(r=0.289,P=0.001)呈正相关。在调整相关混杂因素后,多元线性回归显示血清25(OH)D水平降低与较低的HGS(β=0.199,95%CI:0.058~0.341,P=0.006)和PS(β=0.052,95%CI:0.017~0.087,P=0.004)独立相关。结论MHD患者血清25(OH)D水平降低是HGS和PS降低的独立相关因素。

关键词： 25羟维生素D 握力捏力肌肉健康维持性血液透析

On a Nonlocal Problem Modelling Ohmic Heating in Planar Domains

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Acta Mathematica Sinica,English Series 2013年第3期29卷 523-534页

作者： Fei LIANG qi lin LIU Yu Xiang LI School of Mathematics and Physics Xi'an University of Science and Technology Xi'an 710054 P. R. China Department of Mathematics Anhui Science and Technology University Fengyang 233100 P. R. China Department of Mathematics Southeast University Nanjing 210096 P. R. China

In this paper, we consider the nonlocal problem of the formand the associated nonlocal stationary problemwhere λ is a positive parameter. For Ω to be an annulus, we prove that the nonlocal stationary problem has a unique solution if and only if λ 〈 2｜Ω｜2, and for λ = 2｜Ω｜2, the solution of the nonlocal parabolic problem grows up globally to infinity as t→∞.

关键词： Nonlocal elliptic problems nonlocal parabolic problems blow-up in infinite time

基于熵权法—PSR模型的重庆市大气污染治理政策效果评价

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环境科学导刊 2024年第3期43卷 89-96页

作者：张峻万其林邵景安重庆师范大学地理与旅游学院重庆401331 重庆师范大学三峡库区地表过程与环境遥感重庆市重点实验室重庆401331

采用PSR模型构建重庆市大气污染治理政策效果评价指标体系,通过熵权法与综合指数法对政策效果综合评价,并引进障碍度模型进行障碍因子判断。结果表明,重庆市大气污染治理政策效果显著提升,大气环境质量得到明显改善,压力、状态、响应层... 详细信息

采用PSR模型构建重庆市大气污染治理政策效果评价指标体系,通过熵权法与综合指数法对政策效果综合评价,并引进障碍度模型进行障碍因子判断。结果表明,重庆市大气污染治理政策效果显著提升,大气环境质量得到明显改善,压力、状态、响应层面总体上取得了较满意的效果;工业废气排放持续有效控制尚需加强和人均机动车保有量持续增加,NO_(2)、O_(3)污染物排放控制力度需要加强;缺乏较为完善的大气环境污染协同防治体系,是制约重庆市大气污染治理政策效果的重要障碍因素。因此,加强工业氮氧化物和挥发性有机物的深度治理、加强新生产和在用汽车排放管理和完善“政-企-民”协同防治体系,是进一步提升大气污染治理政策效果主要着力点。

关键词：大气污染治理 PSR模型障碍度政策效果评价

Influencing Factors of Seed Long-distance Dispersal on a Fragmented Forest Landscape on Changbai Mountains,China

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Chinese Geographical Science 2016年第1期26卷 68-77页

作者： ZHAO Fuqiang qi lin FANG Lei YANG Jian State Key Laboratory of Forest and Soil Ecology Institute of Applied EcologyChinese Academy of Sciences

Seed long-distance dispersal(LDD) events are typically rare, but are important in the population processes that determine large-scale forest changes and the persistence of species in fragmented landscapes. However, previous studies focused on species dispersed via animal-mediated LDD, and ignored those dispersed by wind. The aim of this study was to assess the effects of canopy openness, edge, seed source, and patch tree density on the LDD of seeds by wind in forest. We collected birch seeds, a typical wind-dispersed species, throughout a larch plantation. We then assessed the relationship between birch LDD and each factor that may influence LDD of seeds by wind including distance to edge, canopy openness size, distance to mature forest, and the tree density of the larch plantation. We used univariate linear regression analysis to assess the influence of those factors on birch LDD, and partial correlations to calculate the contribution of each factor to LDD. The results showed that both canopy openness and edge had significant influences on birch LDD. Specifically, a negative relationship was observed between distance to edge and birch LDD, whereas there was a positive correlation between canopy openness size and LDD. In contrast, the distance to the mature forest was not correlated with birch LDD. Our results suggest that patch tree density could potently affect the probability of LDD by wind vectors, which provides novel and revealing insights regarding the effect of fragmentation on wind dynamics. The data also provide compelling evidence for the previously undocumented effect of habitat fragmentation on wind-dispersed organisms. As such, these observations will facilitate reasonable conservation planning, which requires a detailed understanding of the mechanisms by which patch properties hamper the delivery of seeds of wind-dispersed plants to fragmented areas.

关键词： seed long-distance dispersal (LDD) forest fragmentation patch property wind dispersal Changbai Mountains