检索结果-南通市图书馆

Durable Ru Nanocrystal with HfO_(2)Modification for Acidic Overall Water Splitting

在线全文

学校读者我要写书评

暂无评论

Nano-Micro Letters 2024年第9期16卷 462-477页

作者： Xiangkai kong jie Xu Zhicheng Ju Changle Chen School of Materials and Physics China University of Mining and TechnologyXuzhou 221116JiangsuPeople’s Republic of China Anhui Province Key Laboratory of Pollutant Sensitive Materials and Environmental Remediation Huaibei Normal UniversityHuaibei 235000AnhuiPeople’s Republic of China School of Chemistry and Materials Science University of Science and Technology of ChinaHefei 230026AnhuiPeople’s Republic of China School of Chemistry and Chemical Engineering Nanjing UniversityNanjing 210023JiangsuPeople’s Republic of China

Durable and efficient bi-functional catalyst,that is capable of both oxygen evolution reaction and hydrogen evolution reaction under acidic condition,are highly desired for the commercialization of proton exchange membrane water ***,we report a robust L-Ru/HfO_(2)heterostructure constructed via confining crystalline Ru nanodomains by HfO_(2)*** assembled with a proton exchange membrane,the bi-functional L-Ru/HfO_(2)catalyst-based electrolyzer presents a voltage of 1.57 and 1.67 V to reach 100 and 300 mA cm^(-2)current density,prevailing most of previously reported Ru-based materials as well as commercial Pt/C||RuO_(2)*** is revealed that the synergistic effect of HfO_(2)modification and small crystalline domain formation significantly alleviates the over-oxidation of *** importantly,this synergistic effect facilitates a dual-site oxide path during the oxygen evolution procedure via optimization of the binding configurations of oxygenated *** a result,the Ru active sites maintain the metallic state along with reduced energy barrier for the rate-determining step(^(*)O→^(*)OOH).Both of water adsorption and dissociation(Volmer step)are strengthened,while a moderate hydrogen binding is achieved to accelerate the hydrogen desorption procedure(Tafel step).Consequently,the activity and stability of acidic overall water splitting are simultaneously enhanced.

关键词： Ruthenium Hafnium dioxide Oxygen evolution catalysis Anti-oxidation

凡纳滨对虾大水面高盐养殖水体叶绿素a的变化及与环境因子的关系

在线全文

学校读者我要写书评

暂无评论

渔业科学进展 2024年第1期45卷 118-127页

作者：孙怡茹张继红吴文广杜彦秋孙威冯旭康秦梓孔杰中国水产科学研究院黄海水产研究所、农业农村部海洋渔业与可持续发展重点实验室山东青岛266071 海洋渔业科学与食物产出过程功能实验室山东青岛266071 中国农业科学院研究生院北京100081

“渔盐一体化”是山东省滨州市凡纳滨对虾(Litopenaeus vannamei)盐田养殖的重要模式。为了解该模式下养殖水体浮游植物的叶绿素a(Chl-a)浓度、粒径结构的变化特征及主要影响因子,于2021年5—7月分别在养殖的初期、中期和收获期,测定高... 详细信息

“渔盐一体化”是山东省滨州市凡纳滨对虾(Litopenaeus vannamei)盐田养殖的重要模式。为了解该模式下养殖水体浮游植物的叶绿素a(Chl-a)浓度、粒径结构的变化特征及主要影响因子,于2021年5—7月分别在养殖的初期、中期和收获期,测定高盐组(S=54)和对照组(S=32)养殖水体的分级Chl-a浓度[小型浮游植物(micro Chl-a)、微型浮游植物(nano Chl-a)、微微型浮游植物(pico Chl-a)、总Chl-a浓度]及相关环境参数的日变化和月变化。结果显示,日变化:对于总Chl-a浓度,高盐组无显著日变化(P>0.05),对照组在5月和6月存在显著的日差异(P<0.05)。对于浮游植物粒径结构,高盐组7月的pico Chl-a日变化显著(P<0.05);对照组7月的micro Chl-a和6月的nano Chl-a日变化显著(P<0.05)。月变化:两盐度组pico Chl-a、nano Chl-a和total Chl-a最低值和最高值都分别出现在6月和7月。且7月的总Chl-a显著高于5月和6月(P<0.05)。高盐组水体中nanoChl-a占主要优势,随着养殖的进行粒径结构特性出现了演替,其中,picoChl-a对总Chl-a贡献率由5月的6.43%提高至7月的16.81%,超过了micro Chl-a的贡献率。对照组5月和6月以micro Chl-a占主要优势,分别占59.64%和57.49%,其次是nano Chl-a,分别占35.46%和36.90%,7月以nano Chl-a占主要优势,贡献率达53.09%。冗余分析(RDA)显示,Chl-a浓度与水温显著正相关,nanoChl-a的贡献率随温度升高而增加。高盐组总Chl-a浓度与硅酸盐浓度呈显著正相关,与磷酸盐、溶解有机氮、溶解有机磷浓度呈显著负相关;对照组总Chl-a与溶解有机氮显著正相关,与硅酸盐、亚硝酸盐浓度呈显著负相关。总体来讲,高盐组水体Chl-a浓度日变化较小,浮游植物粒级随养殖进行逐渐趋于小型化,可能与温度升高和较高的有机氮水平有关。

关键词：凡纳滨对虾叶绿素a 粒级结构营养盐海水养殖池塘

同方期刊数据库博看期刊

Single source precursor derived SiBCNHf ceramic with enhanced high-temperature microwave absorption and antioxidation

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2022年第31期126卷 215-227页

作者： Yan Song Ziyu Liu Xicheng Zhang Runqiu Zhu Youwei Zhang Pinggui Liu Lihua He jie kong MOE Key Laboratory of Space Applied Physics and Chemistry School of Chemistry and Chemical EngineeringNorthwestern Polytechnical UniversityXi’an 710072China AECC Beijing Institute of Aeronautical Materials Beijing 100095China

Electromagnetic(EM)wave-absorbing materials with high-temperature-resistance are urgently desirable to eliminate EM interference in extreme *** derived ceramics(PDC)route is being evolved as an effective strategy to solve the ***,a single source hyperbranched polyborosi-lazane precursor containing hafnium(hb-PBSZ-Hf)is introduced and the SiBCNHf ceramic is obtained by further *** micro-sized tissues including HfC,SiC,HfB 2 nanocrystals and segregated carbons are in situ generated during annealing which not only increase EM wave absorption ability(minimum re-flection coefficient(RC_(min))is-56.71 dB with a thickness of 2.5 mm,effective absorption bandwidth(EAB)is 3.4 GHz),but also improve antioxidation property(less than 2 wt.%mass fluctuation at 1400℃in air).Theoretical simulation of complex permittivity suggests that SiBCNHf ceramic has an RC_(min)of less than-5 dB for the whole X-band even at 1100℃.Such SiBCNHf ceramic with superior high-temperature-resistance and antioxidation performance derived from single source precursors possesses great potential for EM wave absorbing coatings in high-temperature and harsh environments.

关键词： hb-PBSZ-Hf precursor SiBCNHf ceramic EM wave absorption Antioxidation performance

围产期孕期饮食营养干预指导对妊娠期糖尿病孕妇体重及妊娠结局的影响

在线全文

学校读者我要写书评

暂无评论

四川生理科学杂志 2024年第5期46卷 1030-1031,1067页

作者：孔鹏杰郭珊珊王多多信阳市妇幼保健院产科河南信阳464000

目的:探讨围产期孕期饮食营养干预指导对妊娠期糖尿病(Gestational diabetes mellitus,GDM)孕妇体重及妊娠结局的影响。方法:选取本院2022年1月至2023年1月期间收治的GDM孕妇98例作为研究对象。以随机数字表法将患者分为对照组和研究组,... 详细信息

目的:探讨围产期孕期饮食营养干预指导对妊娠期糖尿病(Gestational diabetes mellitus,GDM)孕妇体重及妊娠结局的影响。方法:选取本院2022年1月至2023年1月期间收治的GDM孕妇98例作为研究对象。以随机数字表法将患者分为对照组和研究组,各49例。对照组给予常规营养管理,研究组采用孕期饮食营养干预指导。分析比较两组干预前(孕28 w)、后(分娩前)血糖控制情况(空腹血糖、餐后2 h血糖),比较干预前(孕28 w)、干预后(分娩前)的体重变化及母婴不良妊娠结局。结果:干预后,研究组空腹血糖、餐后2h血糖均显著低于对照组(P<0.05);分娩前体重显著低于对照组(P<0.05);母婴不良妊娠结局总发生率(10.20%)显著低于对照组(53.06%)(P<0.05)。结论:围产期对GDM孕妇进行孕期饮食营养干预指导,可有效调控孕妇血糖水平,控制孕妇体重,改善母婴不良妊娠结局。

关键词：围产期孕期饮食营养干预妊娠期糖尿病妊娠结局

喀斯特山区筑坝河流水-气界面CO_(2)通量变化特征及影响因素分析

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

地球与环境 2024年第1期52卷 11-20页

作者：张富强周忠发孔杰丁圣君王翠谢江婷温朝程邹艳贵州师范大学地理与环境科学学院/喀斯特研究院贵阳550001 贵州喀斯特山地生态环境国家重点实验室培育基地贵阳550001

水库是内陆水域生态系统的重要组成部分,在调节区域和全球碳循环中发挥着重要作用,为了解喀斯特山区筑坝河流水-气界面CO_(2)扩散通量的变化特征及影响因素,本研究以贵州省黔中水利枢纽工程区平寨水库为对象,于2020年1月、5月、7月和11... 详细信息

水库是内陆水域生态系统的重要组成部分,在调节区域和全球碳循环中发挥着重要作用,为了解喀斯特山区筑坝河流水-气界面CO_(2)扩散通量的变化特征及影响因素,本研究以贵州省黔中水利枢纽工程区平寨水库为对象,于2020年1月、5月、7月和11月对其水体理化指标进行系统监测,运用TBL模型法计算水-气界面CO_(2)扩散通量。结果表明,平寨水库水化学类型为HCO_(3)+SO_(4)-Ca型,水化学特征主要受碳酸盐岩风化控制;表层水体pCO_(2)与CO_(2)扩散通量变化范围分别在124.64~558.76μatm和-18.85~15.90 mg/(m^(2)·d)之间,1月表现为大气CO_(2)的源,5月、7月、11月均表现为大气CO_(2)的汇;垂向上水体pCO_(2)变化范围为124.64~5409μatm,表现为表层低、底层高的差异特征。分析认为,影响平寨水库水-气界面CO_(2)扩散通量的因素主要是:碳酸盐岩平衡体系改变了水中碳化物的存在形态使其水体pCO_(2)发生变化、浮游植物光合作用对水体碳化合物的吸收从而抑制CO_(2)向大气扩散,以及水库热分层期时对底层水体CO_(2)暂封存和混合期时底层水体发生上覆脱气的影响。

关键词： CO_(2)扩散通量变化特征影响因素喀斯特水库

The modification toward excited-state dynamics and catalytic activity by isomeric Au_(44)clusters

在线全文

学校读者我要写书评

暂无评论

Nano Research 2023年第8期16卷 11383-11388页

作者： Tongxin Song jie kong Shisi Tang Xiao Cai Xu Liu Meng Zhou Wen Wu Xu Weiping Ding Yan Zhu School of Chemistry and Chemical Engineering Nanjing UniversityNanjing 210093China Hefei National Research Center for Physical Sciences at the Microscale University of Science and Technology of ChinaHefei 230026China School of Physical Science and Technology Ningbo UniversityNingbo 315211China

The structure determination of metal nanoclusters protected by ligands is critical in understanding their physical and chemical properties,yet it remains elusive how the metal core and ligand of metal clusters cooperatively contribute to the observed ***,with the successful synthesis of Au_(44)TBPA_(22)Cl_(2)cluster(TBPA=4-tert-butylphenylacetylene),the structural isomer of previously reported Au_(44)L_(28)clusters(L denoted as ligand)is filled,thereby providing an opportunity to explore the property evolution rules imparted by different metal core structures or different surface ***-resolved transient absorption spectroscopy reveals that the difference in the core structure between Au_(44)TBPA_(22)Cl_(2)and Au_(44)L_(28)can bring nearly 360 times variation of excited-state lifetime,while only 3–24 times differences in excited-state lifetimes of the three Au_(44)L_(28)nanoclusters with identical metal core but different ligands are observed,which is due to much stronger impact of the metal core than the surface ligands in the electronic energy bands of the *** addition,the Au_(44)clusters protected by alkyne ligands are shown to be highly effective toward the electrochemical oxidation of ethanol,compared to the Au_(44)clusters capped by thiolates,which is ascribed to smaller charge transfer impedance of the former *** anticipate that the study will enhance the process in controlling the nanomaterial properties by precisely tailoring metal core or surface patterns.

关键词： cluster metal core surface ligand excited-state dynamics catalysis

Hybrid Polymer Membrane Functionalized PBO Fibers/Cyanate Esters Wave‑Transparent Laminated Composites

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Advanced Fiber Materials 2022年第3期4卷 520-531页

作者： Zheng Liu Xiaoli Fan Lei Cheng Junliang Zhang Lin Tang Yusheng Tang jie kong Junwei Gu Shaanxi Key Laboratory of Macromolecular Science and Technology School of Chemistry and Chemical EngineeringNorthwestern Polytechnical UniversityXi’anShaanxi 710072People’s Republic of China State Key Laboratory of Solidifcation Processing Northwestern Polytechnical UniversityXi’anShaanxi 710072People’s Republic of China Aerospace Research Institute of Materials and Processing Technology Beijing 100076People’s Republic of China

Hybrid polymer membrane(TA-APTES),synthesized by tannic acid(TA)and aminopropyl trethoxysilane(APTES)based on the Schif’s base and Michael addition reaction,is deposited on the surface of poly(p-phenylene-2,6-benzobisoxazole)(PBO)fbers,and then grafted with epoxy-terminated polysesquisiloxane(POSS)to obtain POSS-g-PBO@TA-APTES *** POSS-g-PBO@TA-APTES fbers reinforced bisphenol A dicyanate ester(BADCy)resins(POSS-g-PBO@TAAPTES fbers/BADCy)wave-transparent laminated composites are *** interlaminar shear strength and fexural strength of POSS-g-PBO@TA-APTES fbers/BADCy composites are respectively enhanced from 36.7 and 587.4 MPa to 42.8 and 645.8 MPa,increased by 16.6%and 9.9%compared with those of PBO fbers/BADCy *** 1 MHz,the corresponding dielectric constant and dielectric loss are reduced to 2.85 and 0.0047,respectively,lower than those of PBO fbers/BADCy(3.06 and 0.006)***,the simulated wave transmittance rate of POSS-g-PBO@TA-APTES fbers/BADCy composites with the thicknesses of 1.5–3.5 mm is higher than 86.2%at 0.3–40 *** volume resistivity and breakdown strength of POSS-g-PBO@TA-APTES fbers/BADCy composites are 2.8×10^(15)Ω·cm and 19.80 kV/mm,higher than PBO fbers/BADCy composites(2.2×10^(15)Ω·cm and 17.69 kV/mm),*** the corresponding heat resistant index is 221.5℃,lower than PBO fbers/BADCy composites(229.6℃).

关键词： Poly(p-phenylene-2,6-benzobisoxazole)fbers Bisphenol A dicyanate ester resins Wave-transparent laminated composites Interlaminar shear strength Surface functionalization

线性上升速率对导管头端不稳定状态下行数字减影血管造影的影响

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

中华介入放射学电子杂志 2024年第2期12卷 161-165页

作者：项玉梅许少睿孔杰张金美李晗南京医科大学附属南京医院(南京市第一医院)介入血管科江苏南京210006

目的减少或消除选择性数字减影血管造影(digital subtraction angiography,DSA)时导管头端和靶血管开口的不稳定性,提高造影成功率和显示清晰度。方法选择2020年1月至2022年12月南京市第一医院在选择性脑血管DSA造影术中,导管头端有弹... 详细信息

目的减少或消除选择性数字减影血管造影(digital subtraction angiography,DSA)时导管头端和靶血管开口的不稳定性,提高造影成功率和显示清晰度。方法选择2020年1月至2022年12月南京市第一医院在选择性脑血管DSA造影术中,导管头端有弹离靶血管现象患者98例。根据血管直径大小,将椎动脉和颈总动脉造影分别收集样本入组,并按照使用线性上升速率参数的不同进行分组,并重新造影;对比使用不同线性上升速率导管头端的稳定性、靶血管显示的清晰度和对患者的刺激感。结果导管头端在椎动脉和颈总动脉开口处造影时,导管稳定性随线性上升速率的延长而增加,试验组与对照组稳定性对比,P=0.000,具有统计学意义;对比剂对患者的刺激感随线性上升速率的延长而降低;在对比剂注射总量不变的情况下,随着线性上升速率的延长,血管显影密度有下降的趋势;但根据线性上升速率时间长短,补偿相应注射总量,可克服这种密度下降趋势。结论通过设置线性上升速率,可保持造影时导管头端的稳定性,减少弹离血管开口机率和对比剂对血管内膜的刺激,提高造影成功率、清晰度和安全性。

关键词：血管造影导管头稳定性线性上升速率清晰度

Hollow hydrangea-like nitrogen-doped NiO/Ni/carbon composites as lightweight and highly efficient electromagnetic wave absorbers

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Nano Research 2022年第8期15卷 6831-6840页

作者： Jin Liang Chunwei Li Xin Cao Yuxiang Wang Zongcheng Li Benzheng Gao Zeyou Tong Bin Wang Shuchen Wan jie kong MOE Key Laboratory of Materials Physics and Chemistry in Extraordinary Conditions Shaanxi Key Laboratory of Macromolecular Science and TechnologySchool of Chemistry and Chemical EngineeringNorthwestern Polytechnical UniversityXi’an 710072China China Academy of Launch Vehicle Technology Beijing 100076China Minmetals exploration&development CO.LTD Beijing 100010China

Hierarchical hollow-structured magnetic–dielectric materials are considered to be promising and competitive functional absorbers for microwave absorption(MA).Herein,a hierarchical hollow hydrangea multicomponent metal oxides/metal-carbon was designed and successfully produced via a facile self-assembly method and calcination *** magnetic NiO and Ni nanoparticles were suspended within the hollow hydrangea-like nitrogen-doped carbon matrix(HH N-NiO/Ni/C),constructing a unique hierarchical hollow structured multicomponent magnetic–dielectric MA *** annealing temperature and oxidation time were carefully regulated to investigate the complex permittivity and *** N-NiO/Ni/C delivers exceptional MA properties with maximum reflection loss of–45.8 dB at 1.7 mm thickness and displays a wide effective absorption frequency range of 5.6 *** superior MA performance can be attributed to the following aspects:(1)The hierarchical hollow multicomponent structure offers plentiful of heterojunction interfaces triggering interfacial polarization;(2)nitrogen doped-carbon(N-C)facilitates the conductive loss by the unique electron migration path in the graphitized C and NiO/Ni;(3)magnetic NiO/Ni nanoparticles homogeneously dispersed within N-C form extensive C skeleton and strengthen the magnetic response ability;(4)hierarchical hollow wrinkled structures possess a large interspace and heterogeneous interface improving polarization loss and enhancing multireflection process and the unique structure satisfies magnetic and dielectric loss simultaneously resulting from synergistic effects of different components within the composites.

关键词： hierarchical magnetic-dielectric composites hollow hydrangea-like structure impedance matching nitrogen doped NiO/Ni/C microwave absorption