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Impact of vegetation coverage and configuration on urban temperatures:a comparative study of 31 provincial capital cities in China
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作者 Chengcong Wang Zhibin Ren +6 位作者 peng zhang Yujie Guo Shengyang Hong Wenhai Hong Xinyu Wang Ruoxuan Geng Fanyue Meng 《Journal of Forestry Research》 2025年第1期163-177,共15页
Urban vegetation plays a crucial role in regulating temperatures and heat waves in urban areas.However,the influence of vegetation coverage and its configuration on surface temperatures in different climate zones at a... Urban vegetation plays a crucial role in regulating temperatures and heat waves in urban areas.However,the influence of vegetation coverage and its configuration on surface temperatures in different climate zones at a national scale is unclear.To address this,we utilized high-resolution data to detect spatial patterns for 31 provincial capital cities in China.We integrated day and night surface temperatures to determine the influence of vegetative coverage and configuration on urban temperatures across different climate zones and city sizes.Our study revealed that a subtropical monsoon climate and medium-sized cities had the highest vegetative coverage and shape complexity.The best connectivity and agglomeration of vegetation were found in a temperate monsoon climate and large cities.In contrast,small cities,especially those under a temperate continental climate,had low vegetation coverage,high fragmentation,and weak agglomeration and connectivity.In addition,vegetative coverage had a negative impact on daytime surface temperatures,especially in large cities in a subtropical monsoon climate.However,an increase in vegetation coverage could result in warming at night in small cities in temperate continental climates.Although urban vegetation configuration also contributed to moderating surface temperatures,especially at night,they did not surpass the influence of vegetation coverage.The effect on nighttime temperatures of the configuration of vegetation increased by 3–6%relative to that of daytime temperatures,especially in large cities in a temperate monsoon climate.The contribution vegetation coverage and configuration interaction to cooling efficiency decreased at night,especially in medium-sized cities in a temperate continental climate by 3–5%.In addition,this study identified several moderating effects of natural and social factors on the relationship between urban vegetation coverage and surface temperatures.High duration of sunshine,low humidity and high wind speed significantly enhanced the negative impact of vegetation coverage on surface temperatures.In addition,the moderating effect of vegetation coverage was more pronounced in low population density cities and high gross domestic product.This study enhances understanding of the ecological functions of urban vegetation and provides a valuable scientific basis and strategic recommendations for optimizing urban vegetation and improving urban environmental quality. 展开更多
关键词 Daytime and nighttime urban temperatures Landscape patterns Moderating effect Urban vegetation coverage
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无机化学中“酸碱解离”教学内容的重构探讨
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作者 李淑妮 翟全国 +4 位作者 王颖 袁文玉 张鹏 胡满成 高胜利 《大学化学》 CAS 2024年第1期57-62,共6页
依据素质教育中知识-能力-素质有机融合的思想指导,对《无机化学》酸碱解离内容进行重组,构建新的课程设计模块。内容重组扩充为5个模块,包括电解质溶液基础、酸碱理论概述、酸碱强度、弱酸弱碱解离平衡和酸碱滴定与误差基本概念。教学... 依据素质教育中知识-能力-素质有机融合的思想指导,对《无机化学》酸碱解离内容进行重组,构建新的课程设计模块。内容重组扩充为5个模块,包括电解质溶液基础、酸碱理论概述、酸碱强度、弱酸弱碱解离平衡和酸碱滴定与误差基本概念。教学内容的重构在保证基本面知识结构完整的前提下与时俱进,从专业能力方面促进学生发展。 展开更多
关键词 电解质 酸碱理论 酸碱平衡 误差 课程重组
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无机化学中“配位化学基础”教学内容的重构探讨
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作者 翟全国 张鹏 +4 位作者 袁文玉 王颖 李淑妮 胡满成 高胜利 《大学化学》 CAS 2024年第11期117-130,共14页
一流的教学内容要求达到“知识-能力-素质有机融合”。“配位化学基础”教学内容作为无机化学理论基础之一的主章节,应在教育部提倡的“专业-能力-素质有机融合”育人精神指导下,突破长期存在的固化框架,构建新的课程设计,加强基础概念... 一流的教学内容要求达到“知识-能力-素质有机融合”。“配位化学基础”教学内容作为无机化学理论基础之一的主章节,应在教育部提倡的“专业-能力-素质有机融合”育人精神指导下,突破长期存在的固化框架,构建新的课程设计,加强基础概念的科学性和准确性,培养学生学以致用的能力,提高学生的科学素养,体现“高阶性、创新性和挑战度”。提议将章名改为“配位化合物基础及应用”,内容扩充描绘为6个模块;尽量使教学内容的重构在保证基本面知识结构的前提下与时俱进,适当凸显配位化学发展中的最新理论、最新研究成果、最新前沿、实践成果;同时凸显“专业与思政同向同行”,充分发挥课程育人功能,从专业、能力、素质全方位促进学生学业发展。 展开更多
关键词 配位化学基础 内容结构重组 课程设计 课程思政 学生发展
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构建共价三嗪框架/氮掺杂碳包覆氧化亚铜S型异质结促进光催化制氢
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作者 黄凯辉 陈德俊 +4 位作者 张欣 沈荣晨 张鹏 许第发 李鑫 《物理化学学报》 SCIE CAS CSCD 北大核心 2024年第12期19-20,共2页
开发用于制氢的高效光催化剂在可持续能源研究中至关重要。本研究设计并制备了一种具有S型异质结结构的共价三嗪框架(CTF)-Cu_(2)O@NC复合材料,旨在提高光催化制氢的效率。由于氮掺杂碳(NC)层和S型异质结的协同效应,复合物的光吸收能力... 开发用于制氢的高效光催化剂在可持续能源研究中至关重要。本研究设计并制备了一种具有S型异质结结构的共价三嗪框架(CTF)-Cu_(2)O@NC复合材料,旨在提高光催化制氢的效率。由于氮掺杂碳(NC)层和S型异质结的协同效应,复合物的光吸收能力、电子-空穴分离效率和产氢活性显著增强。该系统的结构和光电化学表征表明,S型异质结不仅提高了光生载流子的分离效率,而且还保持了很强的氧化还原能力,从而进一步促进了光催化反应。此外,NC层可以同时减少Cu_(2)O的光腐蚀并促进电子转移。实验结果表明,CTF-7%Cu_(2)O@NC复合材料在可见光照射下表现出优异的制氢性能,达到15645μmol·g^(-1)·h^(-1),大大超过了纯CTF的光催化活性(2673μmol·g^(-1)·h^(-1))。这项研究为开发高效、创新的光催化材料提供了一种新方法,有力地支持了可持续氢能源的发展。 展开更多
关键词 光催化制氢 Cu_(2)O@NC 共价三嗪框架(CTF) S型异质结 氮掺杂碳
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Ordered mesoporous materials for water pollution treatment:Adsorption and catalysis 被引量:2
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作者 peng zhang Mingming He +4 位作者 Wei Teng Fukuan Li Xinyuan Qiu Kexun Li Hao Wang 《Green Energy & Environment》 SCIE EI CAS CSCD 2024年第8期1239-1256,共18页
To meet the growing emission of water contaminants,the development of new materials that enhance the efficiency of the water treatment system is urgent.Ordered mesoporous materials provide opportunities in environment... To meet the growing emission of water contaminants,the development of new materials that enhance the efficiency of the water treatment system is urgent.Ordered mesoporous materials provide opportunities in environmental processing applications due to their exceptionally high surface areas,large pore sizes,and enough pore volumes.These properties might enhance the performance of materials concerning adsorption/catalysis capability,durability,and stability.In this review,we enumerate the ordered mesoporous materials as adsorbents/catalysts and their modifications in water pollution treatment from the past decade,including heavy metals(Hg^(2+),Pb^(2+),Cd^(2+),Cr^(6+),etc.),toxic anions(nitrate,phosphate,fluoride,etc.),and organic contaminants(organic dyes,antibiotics,etc.).These contributions demonstrate a deep understanding of the synergistic effect between the incorporated framework and homogeneous active centers.Besides,the challenges and perspectives of the future developments of ordered mesoporous materials in wastewater treatment are proposed.This work provides a theoretical basis and complete summary for the application of ordered mesoporous materials in the removal of contaminants from aqueous solutions. 展开更多
关键词 Water pollution treatment Ordered mesoporous materials Toxic contaminants ADSORPTION CATALYSIS
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Strategies of selective electroreduction of aqueous nitrate to N_(2) in chloride-free system:A critical review 被引量:1
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作者 Fukuan Li Weizhe zhang +2 位作者 peng zhang Ao Gong Kexun Li 《Green Energy & Environment》 SCIE EI CAS CSCD 2024年第2期198-216,共19页
Electroreduction of nitrate has been gaining wide attention in recent years owing to it's beneficial for converting nitrate into benign N_(2) from the perspective of electrocatalytic denitrification or into value-... Electroreduction of nitrate has been gaining wide attention in recent years owing to it's beneficial for converting nitrate into benign N_(2) from the perspective of electrocatalytic denitrification or into value-added ammonia from the perspective of electrocatalytic NH_(3) synthesis.By reason of the undesired formation of ammonia is dominant during electroreduction of nitrate-containing wastewater,chloride has been widely used to improve N_(2) selectivity.Nevertheless,selective electroreduction of nitrate to N2 gas in chloride-containing system poses several drawbacks.In this review,we focus on the key strategies for efficiently enhancing N_(2) selectivity of electroreduction of nitrate in chloride-free system,including optimal selection of elements,combining an active metal catalyst with another metal,manipulating the crystalline morphology and facet orientation,constructing core–shell structure catalysts,etc.Before summarizing the strategies,four possible reaction pathways of electro-reduction of nitrate to N_(2) are discussed.Overall,this review attempts to provide practical strategies for enhancing N2 selectivity without the aid of electrochlorination and highlight directions for future research for designing appropriate electrocatalyst for final electrocatalytic denitrifi-cation. 展开更多
关键词 NITRATE CHLORIDE ELECTROREDUCTION SELECTIVITY NITROGEN
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Radial growth in Qinghai spruce is most sensitive to severe drought in the Qilian Mountains of Northwest China
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作者 Xuge Wang Liang Jiao +4 位作者 Ruhong Xue peng zhang Dashi Du Mengyuan Wei Qian Li 《Journal of Forestry Research》 SCIE EI CAS CSCD 2024年第3期73-86,共14页
Global warming and frequent extreme drought events lead to tree death and extensive forest decline,but the underlying mechanism is not clear.In drought years,cambial development is more sensitive to climate change,but... Global warming and frequent extreme drought events lead to tree death and extensive forest decline,but the underlying mechanism is not clear.In drought years,cambial development is more sensitive to climate change,but in different phenological stages,the response rela-tionship is nonlinear.Therefore,the dynamic relationship between tree radial growth and climatic/environmental fac-tors needs to be studied.We thus continuously monitored radial growth of Qinghai spruce(Picea crassifolia Kom.)and environmental factors from January 2021 to November 2022 using point dendrometers and portable meteorological weather stations in the central area of the Qilian Mountains.The relationship and stability between the radial growth of Qinghai spruce and environmental factors were compared for different levels of drought in 2021 and 2022.The year 2022 had higher temperatures and less precipitation and was drier than 2021.Compared with 2021,the growing period in 2022 for Qinghai spruce was 10 days shorter,maximum growth rate(Grmax)was 4.5μm·d^(-1) slower,and the initiation of growth was 6 days later.Growth of Qinghai spruce was always restricted by drought,and the stem radial increment(SRI)was more sensitive to precipitation and air relative humidity.Seasonal changes in cumulative radial growth were divided into four phenological stages according to the time of growth onset,cessation,and maximum growth rate(Grmax)of Qinghai spruce.Stability responses of SRI to climate change were stronger in Stage 3 and Stage 4 of 2021 and stronger in Stage 1(initiation growth stage)and Stage 3 of 2022.The results provide important information on the growth of the trees in response to drought and for specific managing forests as the climate warms. 展开更多
关键词 Picea crassifolia Radial growth dynamics Severe drought Response stability Point dendrometer
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Syntheses and properties of associative acrylamide copolymers containing short hydrophobic chains used in a friction reducer for slick-water fracturing
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作者 Ya-Xing Dai Xian-Li zhang +6 位作者 Si-Yuan Liu Feng-Run-Ze zhang Yi-Xi zhang Yu-Tong Sang Jing-Xi Zheng Zhao-Sheng Liu peng zhang 《Petroleum Science》 SCIE EI CAS CSCD 2024年第3期1889-1901,共13页
Two allyldimethylalkyl quaternary ammonium salt(AQAS)monomers,N,N-dimethylallylphenylpropylammonium bromide(AQAS1)and N,N-dimethylallylnonylammonium bromide(AQAS2),were synthesized and used to prepare modified polyacr... Two allyldimethylalkyl quaternary ammonium salt(AQAS)monomers,N,N-dimethylallylphenylpropylammonium bromide(AQAS1)and N,N-dimethylallylnonylammonium bromide(AQAS2),were synthesized and used to prepare modified polyacrylamide materials.Two new drag reducers were synthesized from acrylamide(AM),sodium acrylate(Na AA)and a cationic modified monomer(AQAS1 or AQAS2)via aqueous solution polymerization,and the copolymers were named P(AM/Na AA/AQAS1)and P(AM/Na AA/AQAS2),respectively.The structures of the drag reduction agents were confirmed by IR and1H NMR spectroscopies.The molecular weight(Mw)of P(AM/Na AA/AQAS1)was 1.79×10^(6)g/mol.When the copolymer concentration was 1000 mg/L and the flow rate was 45 L/min,in fresh water the highest drag reduction rate was 75.8%,in 10,000 mg/L Na Cl solution the drag reduction rate decreased to 72.9%.The molecular weight of P(AM/Na AA/AQAS2)was 3.17×10^(6)g/mol.When the copolymer concentration was500 mg/L and the flow rate was 45 L/min,the drag reduction rate reached 75.2%,and in 10,000 mg/L Na Cl solution the drag reduction rate was 73.3%,decreased by approximately 1.9%.The drag reduction rate for partially hydrolyzed polyacrylamide(HPAM)was also investigated,and the results showed that the drag reduction rates for 500 and 1000 mg/L HPAM solutions were merely 43.2%and 49.0%in brine,respectively.Compared with HPAM,both of the above copolymers presented better drag reduction capacities. 展开更多
关键词 Shale gas Slick water Drag reducer Modified monomer COPOLYMERIZATION
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Effect of valence and spin state on ethane dehydrogenation in Fe-S-1 catalyst
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作者 Liusai Huang Yumeng Fo +6 位作者 peng zhang Shaojia Song Xinxin zhang Xueqiu Wu Saeed Soltanali Jian Liu Weiyu Song 《Journal of Energy Chemistry》 SCIE EI CAS CSCD 2024年第10期677-686,I0014,共11页
Light alkanes non-oxidative dehydrogenation is an attractive non-oil route for olefins production.The alkane dehydrogenation reaction is limited by thermodynamic equilibrium,and the C-H bond cleavage is commonly consi... Light alkanes non-oxidative dehydrogenation is an attractive non-oil route for olefins production.The alkane dehydrogenation reaction is limited by thermodynamic equilibrium,and the C-H bond cleavage is commonly considered as the rate-determined step.The valence state of metal sites in catalysts will influence the stabilization of the vital intermediate(i.e.,C_(x)H_(y)...M^(δ+)...H)during the C-H bond cleavage process,which in turn affects the catalytic reactivity.Herein,we explicitly investigated the effect of different valence states of framework-Fe in silicate-1 zeolite on ethane dehydrogenation reaction through the combination of experimental and theoretical study.Fe(Ⅱ)-S-1 and Fe(Ⅲ)-S-1 catalysts are successfully synthesized by ligand-assisted in situ crystallization method,In-situ C_(2)H_6-FTIR shows the higher coverage of hydrocarbon intermediates on Fe(Ⅱ)-S-1,Under the same evaluation co nditio n,Fe(Ⅱ)-S-1 exhibits a higher space time yield of ethylene.Density functional theory(DFT)results reveal that the more coordinate-unsaturated and electron-enriched Fe(Ⅱ)sites boost the first C-H bond activation by slight deformation and efficient electron donation with C_(2)H_(5)^(*)species.Remarkably,the second C-H bond cleavage on Fe(Ⅱ)-S-1 undergoes a spin-crossing process from quintet state to triplet state,which involves a two-electro n-two-orbital interaction,further promoting the formation of ethylene.Microkinetic analysis is consistent with the experimental and DFT results.This work could provide methodology for elucidating the effect of metal valence states on catalytic performance as well as offer guidance for designing more efficient Fe-zeolite catalysts. 展开更多
关键词 IRON Ethane dehydrogenation Electron-enriched Spin crossover DFT
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In-situ construction of abundant active centers on hierarchically porous carbon electrode toward high-performance phosphate electrosorption: Synergistic effect of electric field and capture sites
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作者 peng zhang Fukuan Li +6 位作者 Mingming He Silu Huo Xueli zhang Benqiang Cen Dezhi Fang Kexun Li Hao Wang 《Green Energy & Environment》 SCIE EI CAS CSCD 2024年第1期126-137,共12页
Phosphate removal is crucial for eutrophication control and water quality improvement.Electro-assisted adsorption,an eco-friendly elec-trosorption process,exhibited a promising potential for wastewater treatment.Howev... Phosphate removal is crucial for eutrophication control and water quality improvement.Electro-assisted adsorption,an eco-friendly elec-trosorption process,exhibited a promising potential for wastewater treatment.However,there are few works focused on phosphate electro-sorption,and reported electrodes cannot attach satisfactory removal capacities and rates.Herein,electro-assisted adsorption of phosphate via in-situ construction of La active centers on hierarchically porous carbon(LaPC)has been originally demonstrated.The resulted LaPC composite not only possessed a hierarchically porous structure with uniformly dispersed La active sites,but also provided good conductivity for interfacial electron transfer.The LaPC electrode achieved an ultrahigh phosphate electrosorption capability of 462.01 mg g^(-1) at 1 V,outperforming most existing electrodes.The superior phosphate removal performance originates from abundant active centers formed by the coupling of electricfield and capture sites.Besides,the stability and selectivity toward phosphate capture were maintained well even under comprehensive conditions.Moreover,a series of kinetics and isotherms models were employed to validate the electrosorption process.This work demonstrates a deep understanding and promotes a new level of phosphate electrosorption. 展开更多
关键词 Electro-assisted adsorption ELECTROSORPTION Phosphate removal Active centers MOF-derived carbon
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An innovative approach to effective breeding blanket design for future fusion reactors
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作者 Changle LIU Lei LI +4 位作者 Yanzi HE peng zhang Yu ZHOU Jun SONG Songtao WU 《Plasma Science and Technology》 SCIE EI CAS CSCD 2024年第10期133-138,共6页
An effective breeding blanket is critical to support tritium self-sufficiency for future fusion reactors.The difficulty is to achieve tritium breeding ratio(TBR)target of 1.05 or more.This paper presents a new design ... An effective breeding blanket is critical to support tritium self-sufficiency for future fusion reactors.The difficulty is to achieve tritium breeding ratio(TBR)target of 1.05 or more.This paper presents a new design approach to the blanket design process.It indicates that fusion blanket design is affected by universal functions based on iterations.Three aspects are worth more attention from fusion engineers in the future.The first factor is that the iterations on the material fractions affect not only structure scheme but also TBR variation.The second factor is the cooling condition affecting final TBR due to the change of the structure material proportion.The third factor is temperature field related to the tritium release.In particular,it is suggested that the statistical calculation of effective TBR must be under reasonable control of the blanket temperature field.This approach is novel for blanket engineering in development of a fusion reactor. 展开更多
关键词 TBR tritium release temperature field blanket design fusion reactor
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Bone marrow edema in a postpartum female following ankle sprain: a case report
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作者 peng zhang Junjie zhang +6 位作者 peng Chen Jianjing Lin Jiang Guo Weixuan Liu Zhiwen Luo Qing Wang Xintao zhang 《World Journal of Emergency Medicine》 SCIE CAS CSCD 2024年第4期325-327,共3页
Bone marrow edema(BME)is characterized by an accumulation of interstitial fluid within the bone marrow,the cancellous,hematopoietic compartment within bones.[1]BME is divided into two principal categories:idiopathic o... Bone marrow edema(BME)is characterized by an accumulation of interstitial fluid within the bone marrow,the cancellous,hematopoietic compartment within bones.[1]BME is divided into two principal categories:idiopathic or primary BME,with an unknown etiology,and secondary BME,which occurs as a result of an identifiable underlying pathology.[2]Although the prevalence of BME is not limited to specific demographic parameters,it shows a predilection for males or individuals assigned male at birth,predominantly aged between the ages of 30 and 60 years,especially in cases of bone marrow edema syndrome(BMES),a rare idiopathic variant.[3]The etiological spectrum of BME is diverse,including oncological entities(such as acute myeloid leukemia and osteosarcoma),degenerative diseases(such as osteoarthritis),infectious processes(osteomyelitis),ischemic conditions(avascular necrosis),metabolic dysfunctions(osteoporosis),inflammatory disorders(rheumatoid arthritis),and traumatic injuries(such as stress fractures).[1,2]Clinically,BME primarily manifests as localized pain,often accompanied by joint effusion and warmth near the affected joint.Diagnostic protocols typically include physical examination,serological assays,bone marrow biopsies,dual-energy X-ray absorptiometry(DEXA)scans,magnetic resonance imaging(MRI),and ultrasonography,with computed tomography(CT)scans and radiographs being less effective. 展开更多
关键词 EDEMA INJURIES FEMALE
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Temperature field calculation of rail flash welding
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作者 Rui Xu Min zhang +6 位作者 Zhenkun Gao Guo Zhao Wei Ding Shouming Wang peng zhang Xiang Liu Jingjing Li 《High-Speed Railway》 2024年第2期116-121,共6页
The forging stage of rail flash welding has a decisive influence on joint strength,and the study of the temperature distribution in the process has an important role in further improving joint strength.In this paper,t... The forging stage of rail flash welding has a decisive influence on joint strength,and the study of the temperature distribution in the process has an important role in further improving joint strength.In this paper,three calculation methods for the temperature field are given.First,the finite element model of the temperature field before forging rail flash welding is established by using the transient heat module of Ansys software and verified by infrared temperature measurement.Second,the temperature distribution of different parts of the rail before flash welding is obtained by using infrared thermal imaging equipment.Third,Matlab software is used to calculate the temperature of the non-measured part.Finally,the temperature distribution function along the rail axis is fitted through the temperature measurement data.The temperature distribution before the top forging of the rail flash welding can be used to analyze the joint and heat-affected zone organization and properties effectively and to guide the parameter setting and industrial production. 展开更多
关键词 Flash welding Temperature field Joint strength Software calculation
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纳米SiC基光催化剂研究进展 被引量:11
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作者 何科林 沈荣晨 +4 位作者 郝磊 李佑稷 张鹏 江吉周 李鑫 《物理化学学报》 SCIE CAS CSCD 北大核心 2022年第11期21-44,共24页
工业化无疑促进了经济的发展,提高了生活水平,但也导致了一些问题,包括能源危机、环境污染、全球变暖等,其中这些所产生问题主要是由燃烧煤炭、石油和天然气等化石燃料引起的。光催化技术具有利用太阳能将二氧化碳转化为碳氢化合物燃料... 工业化无疑促进了经济的发展,提高了生活水平,但也导致了一些问题,包括能源危机、环境污染、全球变暖等,其中这些所产生问题主要是由燃烧煤炭、石油和天然气等化石燃料引起的。光催化技术具有利用太阳能将二氧化碳转化为碳氢化合物燃料、从水中制氢、降解污染物等优点,从而在解决能源危机的同时避免环境污染,因此被认为是解决这些问题的最有潜力的技术之一。在各种光催化剂中,碳化硅(SiC)由于其优良的电学性能和光电化学性质,在光催化、光电催化、电催化等领域具有广阔的应用前景。本文首先系统地阐述了各种SiC的合成方法,具体包括模板生长法、溶胶凝胶法、有机前驱物热解法、溶剂热合成法、电弧放电法,碳热还原法和静电纺丝等方法。然后详细地总结了提升SiC光催化活性的各种改性策略,如元素掺杂、构建Z型(S型)体系、负载助催化剂、可见光敏化、构建半导体异质结、负载炭材料、构建纳米结构等。最后重点论述了半导体的光催化机理以及SiC复合物在光催化产氢、污染物降解和CO_(2)还原等领域的应用研究进展,并提出了前景展望。 展开更多
关键词 碳化硅 光催化 光催化析氢 光催化降解 光催化CO_(2)还原
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不同脂质层厚度干眼患者泪膜稳定性的观察研究 被引量:8
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作者 张鹏 韩坤岭 +1 位作者 王延铮 王延岭 《国际眼科杂志》 CAS 北大核心 2023年第5期864-866,共3页
目的:探讨不同脂质层厚度条件下泪膜稳定性的差异。方法:纳入2020-06/2021-12于我院就诊的干眼患者194例384眼,应用角膜地形图仪行双眼泪河高度、首次泪膜破裂时间和脂质层厚度测量,分析不同脂质层厚度条件下双眼泪河高度、首次泪膜破... 目的:探讨不同脂质层厚度条件下泪膜稳定性的差异。方法:纳入2020-06/2021-12于我院就诊的干眼患者194例384眼,应用角膜地形图仪行双眼泪河高度、首次泪膜破裂时间和脂质层厚度测量,分析不同脂质层厚度条件下双眼泪河高度、首次泪膜破裂时间的差异及其相关性。结果:根据脂质层厚度将纳入患者(384眼)分为脂质丰富组(49眼)、脂质平衡组(27眼)、脂质轻微缺乏组(266眼)、脂质显著缺乏组(42眼),四组泪河高度有差异(P=0.022),首次泪膜破裂时间无差异(P=0.322)。脂质层厚度分级与泪河高度呈正相关(r_(s)=0.143,P=0.006),与首次泪膜破裂时间无相关性(r_(s)=-0.090,P=0.083);泪河高度与首次泪膜破裂时间也无相关性(r_(s)=0.038,P=0.460)。结论:泪膜脂质层厚度不同的干眼患者泪膜稳定性无明显差异。 展开更多
关键词 泪膜 脂质层 干眼 泪河高度 泪膜破裂时间
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防振锤对大跨越输电线微风振动影响的试验研究 被引量:4
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作者 汪峰 彭章 +2 位作者 黄欲成 陈池 赵全江 《防灾减灾工程学报》 CSCD 北大核心 2018年第3期563-569,共7页
防振锤安装方式是架空大跨越输电线路防振设计的重要问题。设计制作了防振锤-大跨越输电线体系的微风振动试验模型,研究了不同张力作用下防振锤-输电线体系的振动响应,分析了FR4型防振锤锤头朝向、FR4型和FDN型防振锤混合安装方式对大... 防振锤安装方式是架空大跨越输电线路防振设计的重要问题。设计制作了防振锤-大跨越输电线体系的微风振动试验模型,研究了不同张力作用下防振锤-输电线体系的振动响应,分析了FR4型防振锤锤头朝向、FR4型和FDN型防振锤混合安装方式对大跨越导线的振动影响。试验结果表明:(1)相同激励下,安装防振锤的导线振动幅值要小于未安装防振锤的裸导线,但随着导线张力的增大,防振锤的防振频段收窄,防振效果降低;(2)FR4型防振锤对15-25Hz激励频段的防振效果较好,其大小锤头朝向对导线振动影响较大,锤头朝向不同,防振锤的防振效果不尽相同;(3)采用混合式安装防振锤的防振效果优于同型号的安装方式。 展开更多
关键词 大跨越导线 微风振动 混合安装 防振锤 模拟试验
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应用角膜地形图仪观察老年干眼患者最早泪膜破裂位置
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作者 张鹏 韩坤岭 +1 位作者 王延铮 王延岭 《国际眼科杂志》 CAS 北大核心 2022年第2期340-342,共3页
目的:观察老年干眼患者最早泪膜破裂位置的特征。方法:横断面研究。选取2019-07/12在我院诊治的老年干眼患者154例267眼,143眼为右眼,124眼为左眼。其中男71例,女83例,年龄68~90(平均73.40±4.13)岁。应用角膜地形图仪对患者进行最... 目的:观察老年干眼患者最早泪膜破裂位置的特征。方法:横断面研究。选取2019-07/12在我院诊治的老年干眼患者154例267眼,143眼为右眼,124眼为左眼。其中男71例,女83例,年龄68~90(平均73.40±4.13)岁。应用角膜地形图仪对患者进行最早发生泪膜破裂位置的测量,破裂位置以仪器观察的角膜方位按逆时针顺序分为4个区域,分别对应右眼的鼻上、颞上、颞下、鼻下4个区域和左眼的颞上、鼻上、鼻下、颞下4个区域。记录哪个区域泪膜最先出现破裂,同时记录最早破裂位置距角膜中心的距离。结果:右眼出现泪膜首先破裂最多的区域为鼻下(28.7%),然后是颞下(27.3%)、鼻上(20.3%)、颞上(11.2%),同时出现2~3个区域泪膜破裂占12.6%。左眼出现泪膜首先破裂最多的区域也为鼻下(31.5%),然后是颞下(25.0%)、鼻上(23.4%)、颞上(11.3%),同时出现2~3个区域泪膜破裂占8.9%。双眼之间泪膜破裂区域构成比的比较无差异(χ2=1.443,P=0.837)。双眼鼻下方泪膜破裂位置距角膜中心距离均以>1.5~2mm和>2~2.5mm为主。结论:老年干眼患者泪膜的破裂位置有一定的规律,双眼泪膜首次破裂均以角膜鼻下方为主,双眼没有显著性差异。 展开更多
关键词 干眼 泪膜 角膜地形图仪 老年 角膜
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高分散Co_(0.2)Ni_(1.6)Fe_(0.2)P助催化剂改性P掺杂g-C_(3)N_(4)纳米片高效光催化析氢的研究 被引量:7
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作者 沈荣晨 郝磊 +3 位作者 陈晴 郑巧清 张鹏 李鑫 《物理化学学报》 SCIE CAS CSCD 北大核心 2022年第7期26-35,共10页
随着化石燃料使用的增加和温室气体排放量持续上升,20世纪以来气温上升得更快。开发环境友好型能源取代传统化石燃料是当务之急。氢能源作为-种清洁、高效的能源,被认为是最有希望取代传统化石燃料的能源。光催化水分解水产氢作为为一... 随着化石燃料使用的增加和温室气体排放量持续上升,20世纪以来气温上升得更快。开发环境友好型能源取代传统化石燃料是当务之急。氢能源作为-种清洁、高效的能源,被认为是最有希望取代传统化石燃料的能源。光催化水分解水产氢作为为一种环保型技术被认为是最有前景的氢能生产方法。提高光生电子-空穴对分离效率是构建高效光催化剂的关键。然而,利用高度分散的助催化剂构建高效、稳定的产氢光催化剂仍然是-一个挑战。本文首次成功地采用--步原位高温磷化法制备了高度分散的非贵金属三金属过度金属磷化Co_(0.2)Ni_(1.6)Fe_(0.2)P助催化剂(PCNS-CoNiFeP)掺杂P的石墨相氮化碳纳米片(PCNS)。有趣的是,PCNS-CoNiFeP与传统氢氧前驱体磷化法制备的CoNiFeP相比,没有聚集性,分散性高。X射线衍射(XRD).X射线光电子能谱(XPS).元素映射图像和高分辨率透射电镜(HRTEM)结果表明,PCNS-CoNiFeP已成功合成。紫外-可见吸收光谱结果表明,PCNS-CoNiFeP在200--800 nm波长范围内较PCNS略有增加。光致发光光谱、电化学阻抗谱(EIS)和光电流分析结果表明,CoNiFeP助催化剂能有效促进光生电子空穴对的分离,加速载流子的迁移。线性扫描伏安法(LSV)结果还表明,负载CoNiFeP助催化剂可大大降低CNS的过电位。结果表明,以三乙醇胺溶液为牺牲剂的PCNS-CoNiFeP最大产氢速率为1200 μmol-h^(-1).g^(-1),是纯CNS-Pt(320 μmol-h^(-1).g^(-1))的4倍。在420 nm处的表观量子效率为1.4%。PCNS-CoNiFeP在光催化反应中也表现出良好的稳定性。透射电镜结果表明,6-8 nm的CoNiFeP高度分散在PCNS表面。高度分散的CoNiFeP比聚集的CoNiFeP具有更好的电荷分离能力和更高的电催化析氢活性。由此可见,聚合的CoNiFeP-PCNs(300 μmol-h^(-1).g^(-1))的产氢速率远低于PCNS-CoNiFeP.此外,CNS的P掺杂可以改善其电导率和电荷传输。 展开更多
关键词 三金属磷化物 光催化产氢 无贵金属助催化剂 磷掺杂 石墨相氮化碳
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多孔Nafion膜离子聚合物金属复合材料的制备及性能 被引量:3
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作者 杜野 梁博 +8 位作者 张鹏 赵刚 赵金涛 王伟华 刘甲奇 马昊哲 王运鑫 王冠正 李政勋 《高分子材料科学与工程》 EI CAS CSCD 北大核心 2019年第7期132-140,共9页
离子聚合物金属复合材料(IPMC)是一种新型人工肌肉材料。传统IPMC的含水率较低,其电致动性能较差。文中采用微粒浸析法,利用纳米四氧化三铁粒子成功制备了多孔Nafion膜。多孔Nafion膜含水率是普通Nafion膜的2.5~4.3倍,并且随着纳米粒子... 离子聚合物金属复合材料(IPMC)是一种新型人工肌肉材料。传统IPMC的含水率较低,其电致动性能较差。文中采用微粒浸析法,利用纳米四氧化三铁粒子成功制备了多孔Nafion膜。多孔Nafion膜含水率是普通Nafion膜的2.5~4.3倍,并且随着纳米粒子含量的增加,含水率不断增大。多孔Nafion膜IPMC的输出位移、应变能密度(能量转换效率)和稳定工作时间分别是普通Nafion膜IPMC的1.6~2.5倍、2.8~4.8倍和1.7~2.1倍。总之,Nafion膜中多孔结构的存在提高了IPMC的电致动性能。 展开更多
关键词 离子聚合物金属复合材料 人工肌肉材料 多孔Nafion膜 电致动性能
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不同网格尺寸的聚乙烯醇水凝胶膜的制备及离子渗透性能 被引量:2
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作者 赵宝 马文中 +3 位作者 张鹏 徐荣 张琪 钟璟 《高分子材料科学与工程》 EI CAS CSCD 北大核心 2020年第7期149-157,共9页
聚乙烯醇(PVA)水凝胶膜由于交联网络结构而具有运输特性,通过网格尺寸来调控离子在其中的渗透扩散行为对其选择渗透功能具有重要意义。本文以戊二醛为交联剂制备了具有不同网格尺寸的PVA水凝胶膜,研究了离子在水凝胶膜中的渗透性能。通... 聚乙烯醇(PVA)水凝胶膜由于交联网络结构而具有运输特性,通过网格尺寸来调控离子在其中的渗透扩散行为对其选择渗透功能具有重要意义。本文以戊二醛为交联剂制备了具有不同网格尺寸的PVA水凝胶膜,研究了离子在水凝胶膜中的渗透性能。通过红外光谱、X射线衍射和扫描电镜表征了PVA水凝胶膜的微观结构,计算其凝胶含量、溶胀度和网格尺寸等参数,并将这些参数与离子在PVA水凝胶膜中的渗透扩散性相关联。结果表明,随着交联剂浓度的增加,PVA水凝胶膜的交联程度增加,网格尺寸随之下降,结晶度和溶胀性也明显下降。同时,当网格尺寸从15.07 nm调控到了3.76 nm时,K^+,Na^+,Ca^(2+)和Mg^(2+)的渗透系数也从19.5×10^(-7)cm^2/s,18.0×10^(-7)cm^2/s,12.2×10^(-7)cm^2/s,10.9×10^(-7)cm^2/s分别降到3.44×10^(-7)cm^2/s,2.84×10^(-7)cm^2/s,2.22×10^(-7)cm^2/s,1.76×10^(-7)cm^2/s,实现了对离子在PVA水凝胶膜中的渗透扩散行为的调控。 展开更多
关键词 聚乙烯醇 水凝胶膜 网格尺寸 渗透系数
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