期刊文献+
共找到17,635篇文章
< 1 2 250 >
每页显示 20 50 100
Application of closed-vessel microwave digestion method for the determination of multi-elements in environmental samples by sequential ICP-AES
1
作者 Xu Liqiang, Shen Wangxing and Zhu Jingfang Shanghai Institute of Metallurgy,Academia Sinica,Shanghai 200050,China 《Journal of Environmental Sciences》 SCIE EI CAS CSCD 1989年第2期69-75,共7页
A closed-vessel microwave digestion method is described for the rapid dissolution of environmental samples such as foods, soils and sediments. Depending on the sample type, 0.1-0.2 g sample was decomposed with HNO3/H2... A closed-vessel microwave digestion method is described for the rapid dissolution of environmental samples such as foods, soils and sediments. Depending on the sample type, 0.1-0.2 g sample was decomposed with HNO3/H2O2 or HNO3 / H2O2/HF acid mixture in a PTFE digestion vessel by using microwave heating for 2-3 min at 500W of microwave power. The solution, or to which 0.5 g of boric acid was added, was diluted to 25-50 ml and directly determined by sequential ICP-AES. The accuracy of the procedure was validated by the analysis of six standard reference materials for 10 elements. Ail results were in a good agreements with the certified values. 展开更多
关键词 microwave digestion environmental sampl sequential icp-aes elemental analysis.
在线阅读 下载PDF
ICP-AES法与邻菲罗啉分光光度法测松香中铁元素含量比较分析
2
作者 莫淇斐 莫锦涛 +3 位作者 黄卫强 陈秋虹 莫建光 卢安根 《林产工业》 北大核心 2025年第8期63-66,共4页
随着新兴应用领域的开发和市场需求的持续增长,松香市场将继续保持增长态势。为保证松香产品的质量和销量,解决企业成本倒挂等问题,本研究采用ICP-AES法和邻菲罗啉分光光度法对松香中的铁进行同步检测。结果显示:ICP-AES法的回收率为98.... 随着新兴应用领域的开发和市场需求的持续增长,松香市场将继续保持增长态势。为保证松香产品的质量和销量,解决企业成本倒挂等问题,本研究采用ICP-AES法和邻菲罗啉分光光度法对松香中的铁进行同步检测。结果显示:ICP-AES法的回收率为98.8%,相对标准偏差为4.02%(n=6);邻菲罗啉分光光度法的回收率为97.7%,相对标准偏差为3.35%(n=6),可见两种方法具有相关性,但是在检测效果上没有显著差异。邻菲罗啉分光光度法因所用仪器价格低廉、操作简单、灵敏度较高,更适用于松香中铁元素含量的测定,且效果良好,可在企业中推广使用。 展开更多
关键词 icp-aes 邻菲罗啉分光光度法 松香 铁元素 比较分析
在线阅读 下载PDF
电感耦合等离子体原子发射光谱(ICP-AES)法测定锆英砂选矿流程样品中8种主次成分
3
作者 刘闫 孙启亮 +3 位作者 张丽萍 倪文山 张宏丽 刘磊 《中国无机分析化学》 北大核心 2025年第6期858-866,共9页
锆英砂是一种难以分解的矿物,且其中Zr、Ti、Hf等元素易水解,准确分析其选矿流程样品中的元素含量对采选和评价锆矿资源具有指导作用。实验筛选出最优前处理方法,采用碳酸钠-硼酸熔融,稀盐酸-酒石酸溶液微热提取,优化了熔剂用量、熔融... 锆英砂是一种难以分解的矿物,且其中Zr、Ti、Hf等元素易水解,准确分析其选矿流程样品中的元素含量对采选和评价锆矿资源具有指导作用。实验筛选出最优前处理方法,采用碳酸钠-硼酸熔融,稀盐酸-酒石酸溶液微热提取,优化了熔剂用量、熔融时间、熔融温度等实验条件,建立了电感耦合等离子体原子发射光谱(ICP-AES)法测定锆英砂选矿流程样品中Zr、Ti、Hf、Fe、Mn、Sn、Ba、Al的分析方法。采用基体匹配法克服了测试过程中的基体干扰,优选了Zr 339.198 nm、Ti 336.121 nm、Hf 277.336 nm、Fe 259.940 nm、Mn 257.610 nm、Sn 189.989 nm、Ba 233.527 nm、Al 396.152 nm为分析谱线。实验结果表明,各元素校准曲线的相关系数在0.9993~0.9999,方法检出限为0.0008~0.011μg/g,测定下限为0.003~0.034μg/g。按照实验方法对GBW07156、GBW07157中Zr、Ti、Hf、Fe、Mn、Sn、Ba、Al进行准确度与精密度考察,得出相对标准偏差(RSD,n=9)为0.56%~3.4%,加标回收率为95.0%~104%。同时对锆英砂选矿流程样品进行分析,相对标准偏差(RSD,n=9)为0.94%~3.2%,加标回收率在95.0%~105%。经与其他测定方法比对,结果表明,方法可实现Zr、Ti、Hf、Fe、Mn、Sn、Ba、Al共8种元素的准确测定,可为评价锆英砂选矿流程样品提供理论依据。 展开更多
关键词 锆英砂 碳酸钠 硼砂 电感耦合等离子体原子发射光谱(icp-aes)
在线阅读 下载PDF
碱熔-电感耦合等离子体原子发射光谱法(ICP-AES)法测定锡矿中的锡、硅、锌、铜、铁、铅、砷、铋、锑 被引量:3
4
作者 郑程 陈雯 +2 位作者 周峰 毛林夏 张鸟飞 《中国无机分析化学》 北大核心 2025年第2期264-270,共7页
为解决锡矿石主次元素常规分析法流程长、过程复杂、成本高、仅能单元素测定等问题,通过考察熔剂种类、混合溶剂比例、熔剂与试样质量比例、熔样温度、熔样时间等条件,建立了电感耦合等离子体原子发射光谱法(ICP-AES)法同时测定锡矿中... 为解决锡矿石主次元素常规分析法流程长、过程复杂、成本高、仅能单元素测定等问题,通过考察熔剂种类、混合溶剂比例、熔剂与试样质量比例、熔样温度、熔样时间等条件,建立了电感耦合等离子体原子发射光谱法(ICP-AES)法同时测定锡矿中锡、硅、锌、铜、铁、铅、砷、铋、锑等9种主次元素的方法。实验表明,采用混合熔剂(四硼酸锂∶偏硼酸锂为1∶4)与试样质量比为20∶1,在铂坩埚中1050℃熔融60 min,60 mL盐酸(1+2)溶液中加热浸取,各元素标准工作曲线的线性相关系数均大于0.9999,方法检出限为0.004~0.08μg/mL,测定标准物质的相对标准偏差在1.0%~5.5%,相对误差在0~9.2%。方法检出限低、精密度好、准确度高,能够满足难溶锡矿中多种元素的同时测定。 展开更多
关键词 锡矿 碱熔 四硼酸锂 偏硼酸锂 电感耦合等离子体原子发射光谱法(icp-aes)
在线阅读 下载PDF
沉淀分离-电感耦合等离子体发射光谱法(ICP-AES)测定Ag-Cu-Zn-Cd钎料中镍含量
5
作者 王飞 张永春 +2 位作者 李乔 祁俊杰 陈朝阳 《广州化工》 2025年第19期130-132,共3页
Ag-Cu-Zn-Cd钎料中镍含量作为钎料质量的重要指标,需要建立准确可靠的测定方法。本研究建立了沉淀分离银,电感耦合等离子体原子发射光谱法(ICP-AES)测定Ag-Cu-Zn-Cd钎料中镍含量的分析方法。称取样品0.1000 g,加入4 mL硝酸(1+1)溶解样品... Ag-Cu-Zn-Cd钎料中镍含量作为钎料质量的重要指标,需要建立准确可靠的测定方法。本研究建立了沉淀分离银,电感耦合等离子体原子发射光谱法(ICP-AES)测定Ag-Cu-Zn-Cd钎料中镍含量的分析方法。称取样品0.1000 g,加入4 mL硝酸(1+1)溶解样品,加入20 mL水,缓慢加入2 mL盐酸,搅拌,低温加热至溶液清亮,沉淀凝聚,氯化银沉淀法除银。滤液定容至100 mL,采用ICP-AES进行测定。实验考察了样品溶解条件、分离银实验条件、仪器工作条件,基体干扰、分析谱线等测定影响因素,确立最优实验条件。结果表明:该方法测定Ag-Cu-Zn-Cd钎料中镍的质量分数为0.12%~3.10%,相对标准偏差1.02%~3.87%(RSD,n=7),样品加标回收率97.5%~106.0%,方法简便,已应用于实际检测。 展开更多
关键词 银钎料 icp-aes
在线阅读 下载PDF
Safe flight corridor constrained sequential convex programming for efficient trajectory generation of fixed-wing UAVs 被引量:2
6
作者 Jing SUN Guangtong XU +2 位作者 Zhu WANG Teng LONG Jingliang SUN 《Chinese Journal of Aeronautics》 2025年第1期537-550,共14页
Generating dynamically feasible trajectory for fixed-wing Unmanned Aerial Vehicles(UAVs)in dense obstacle environments remains computationally intractable.This paper proposes a Safe Flight Corridor constrained Sequent... Generating dynamically feasible trajectory for fixed-wing Unmanned Aerial Vehicles(UAVs)in dense obstacle environments remains computationally intractable.This paper proposes a Safe Flight Corridor constrained Sequential Convex Programming(SFC-SCP)to improve the computation efficiency and reliability of trajectory generation.SFC-SCP combines the front-end convex polyhedron SFC construction and back-end SCP-based trajectory optimization.A Sparse A^(*)Search(SAS)driven SFC construction method is designed to efficiently generate polyhedron SFC according to the geometric relation among obstacles and collision-free waypoints.Via transforming the nonconvex obstacle-avoidance constraints to linear inequality constraints,SFC can mitigate infeasibility of trajectory planning and reduce computation complexity.Then,SCP casts the nonlinear trajectory optimization subject to SFC into convex programming subproblems to decrease the problem complexity.In addition,a convex optimizer based on interior point method is customized,where the search direction is calculated via successive elimination to further improve efficiency.Simulation experiments on dense obstacle scenarios show that SFC-SCP can generate dynamically feasible safe trajectory rapidly.Comparative studies with state-of-the-art SCP-based methods demonstrate the efficiency and reliability merits of SFC-SCP.Besides,the customized convex optimizer outperforms off-the-shelf optimizers in terms of computation time. 展开更多
关键词 Fixed-wing unmanned aerial vehicle Efficient trajectory planning Safe flight corridor sequential convex programming Customized convex optimizer
原文传递
微波消解-ICP-AES法测定镍铁中镍、硅、铬、钴、磷、铜 被引量:1
7
作者 张明 《特钢技术》 2025年第1期54-58,共5页
本试验采用正交试验分别确认微波消解的功率、温度、保持时间、混合消解酸比例,同时考察基体效应、镍铁中镍硅铬钴磷铜的分析谱线选择和共存元素干扰,测定各元素的线性方程和检出限,并进行了精密度试验和加标回收试验,建立了一套完整的... 本试验采用正交试验分别确认微波消解的功率、温度、保持时间、混合消解酸比例,同时考察基体效应、镍铁中镍硅铬钴磷铜的分析谱线选择和共存元素干扰,测定各元素的线性方程和检出限,并进行了精密度试验和加标回收试验,建立了一套完整的微波消解-ICP-AES法测定镍铁中镍硅铬钴磷铜的检测方法。结果表明,镍铁的最佳消解方案是为:消解功率600W,消解酸HNO_(3)+H_(2)SO_(4)+H_(2)O_(2)比例(mL)为8+4+1,反应温度220℃,保持时间25min。采用ICP-AES光谱仪测定时,当铁基量为0.05g时对镍铁中各待测元素无明显干扰,共存元素镍对磷的干扰可用IEC校正消除。方法检出限为0.0003%~0.011%,镍铁中镍、硅、铬、钴、磷、铜的线性关系均良好,相对标准偏差(RSD)均<5%,回收率在95.5%~104.5%。该试验方法的精密度和准确度良好,适用于镍铁中镍硅铬钴磷铜含量的检测。 展开更多
关键词 微波消解 icp-aes 镍铁
在线阅读 下载PDF
ICP-AES法测定Ti175高温钛合金中9种元素方法探究
8
作者 康琼 罗策 +2 位作者 李震乾 白焕焕 卢凡 《化学工程师》 2025年第7期38-41,83,共5页
采用HCl-HF-HNO_(3)混合酸溶解试样,探究了电感耦合等离子体原子发射光谱法(ICP-AES)测定Ti175高温钛合金中Al、Mo、Zr、Sn、W、Si、Fe、Ni、Re 9种元素含量的分析方法。考察了分析谱线选择、仪器分析参数优化、合金元素对杂质元素的基... 采用HCl-HF-HNO_(3)混合酸溶解试样,探究了电感耦合等离子体原子发射光谱法(ICP-AES)测定Ti175高温钛合金中Al、Mo、Zr、Sn、W、Si、Fe、Ni、Re 9种元素含量的分析方法。考察了分析谱线选择、仪器分析参数优化、合金元素对杂质元素的基体效应影响,并通过基体合金匹配的方式消除基体效应及分析谱线的干扰。在优化的实验条件(激发功率1150W、雾化气流量0.65L·min^(-1))下,建立工作曲线,各元素线性相关系数r≥0.999,检出限为0.0005%~0.0098%。实际样品分析中,加标回收率为97.0%~102.0%,各元素RSD≤6.94%(n=7)。结果表明,方法精密度良好,准确度高。 展开更多
关键词 高温钛合金 icp-aes 基体干扰 钛合金
在线阅读 下载PDF
ICP-MS/ICP-AES测定矿物药龙骨中55种元素的含量及龙骨来源的鉴别
9
作者 彭韦楠 李丽敏 +4 位作者 曹帅 丁贝贝 胡青 毛秀红 季申 《理化检验(化学分册)》 北大核心 2025年第7期761-768,共8页
取0.1 g龙骨样品粉末置于聚四氟乙烯消解管中,加入5 mL硝酸,密封混匀,于220℃微波消解30 min,冷却,加少量水润洗并转移至50 mL容量瓶中,用水定容,离心。采用电感耦合等离子体原子发射光谱法(ICP-AES)测定上清液中P、S元素的含量,电感耦... 取0.1 g龙骨样品粉末置于聚四氟乙烯消解管中,加入5 mL硝酸,密封混匀,于220℃微波消解30 min,冷却,加少量水润洗并转移至50 mL容量瓶中,用水定容,离心。采用电感耦合等离子体原子发射光谱法(ICP-AES)测定上清液中P、S元素的含量,电感耦合等离子体质谱法(ICP-MS)联合内标法测定其余53种元素的含量。运用IBM SPSS Statistics 26.0软件对37批龙骨样品中检出的51种元素进行相关性分析,SIMCA14.1软件识别龙骨的来源及引起差异的元素。结果表明,P、S元素的质量浓度在一定范围内和对应的信号强度呈线性关系,其余53种元素的质量浓度在一定范围内和对应的信号强度与内标信号强度的比值呈线性关系,检出限(3s)为0.0002~7.916 mg·kg^(−1)。对实际龙骨样品溶液进行精密度试验,测定值的相对标准偏差(n=6)均小于13%。按照标准加入法进行回收试验,回收率为85.0%~114%。方法用于分析37批实际龙骨样品,结果显示龙骨中Ca、P元素含量最高且之间呈显著正相关,Ba、Na、Mg、S、Al、Sr、Fe等元素在不同批次中含量差异较大且元素之间存在不同程度相关,重金属及有害元素含量相对较低,Te、Os、Ru、Pt等元素均未检出;U、Sr、Mg及稀土元素可能是引起不同来源龙骨差异的标志性元素。 展开更多
关键词 矿物药龙骨 电感耦合等离子体质谱法(ICP-MS) 电感耦合等离子体原子发射光谱法(icp-aes) 元素
在线阅读 下载PDF
焙烧碱融-氯酸钠氧化-ICP-AES法测定有机废液中铱含量
10
作者 于惠琪 龚绘林 +5 位作者 田相亮 管有祥 彭鹏 何雄辉 陈名 黄蕾 《贵金属》 北大核心 2025年第S1期222-225,共4页
含铱有机废液成分繁杂,其中不仅包含大量有机溶剂与各类杂质,还含有不同浓度的铱元素。本文采用焙烧-碱融法对含铱有机废液进行分解处理,用氯酸钠溶液进行氧化,得到的试液用ICP-AES法测定废液中铱的含量。实验结果显示,焙烧-碱融法能够... 含铱有机废液成分繁杂,其中不仅包含大量有机溶剂与各类杂质,还含有不同浓度的铱元素。本文采用焙烧-碱融法对含铱有机废液进行分解处理,用氯酸钠溶液进行氧化,得到的试液用ICP-AES法测定废液中铱的含量。实验结果显示,焙烧-碱融法能够有效地分解含铱有机废液。在氧化环节,加入10 mL氯酸钠溶液时氧化效果最佳。在沉淀富集铱的过程中,以碲作为沉淀剂、二氯化锡作为还原剂,可使铱实现完全沉淀富集。方法的相对标准偏差为0.41%~0.76%,加标回收率在100.61%~104.55%之间,满足含铱有机废液中铱含量测定的精密度和准确度要求。本研究方法具有较高的准确性和可靠性,能够满足日常生产与科研工作中对含铱有机废液中铱含量测定的需求。 展开更多
关键词 有机废液 焙烧碱融 氯酸钠氧化 icp-aes
在线阅读 下载PDF
基于动态微波消解与ICP-AES法的土壤重金属元素测定研究 被引量:1
11
作者 马金晔 《中国资源综合利用》 2025年第8期18-20,共3页
为提高土壤中Cu、Mn、Zn、Pb四种重金属测定数据的准确性和可靠性,采用动态微波消解方法处理土壤样品,结合电耦合等离子体原子发射光谱(Inductively Coupled Plasma-Atomic Emission Spectrometry,ICP-AES)法测定重金属元素,并与国标法... 为提高土壤中Cu、Mn、Zn、Pb四种重金属测定数据的准确性和可靠性,采用动态微波消解方法处理土壤样品,结合电耦合等离子体原子发射光谱(Inductively Coupled Plasma-Atomic Emission Spectrometry,ICP-AES)法测定重金属元素,并与国标法进行对比。研究表明,该方法在复杂土壤样品中表现出较高的准确度,能够满足土壤重金属元素分析需求。 展开更多
关键词 动态微波消解 电耦合等离子体原子发射光谱(icp-aes) 土壤 重金属
在线阅读 下载PDF
Construction of a three-step sequential energy transfer system with selective enhancement of superoxide anion radicals for photocatalysis
12
作者 Yusong Bi Rongzhen Zhang +3 位作者 Kaikai Niu Shengsheng Yu Hui Liu Lingbao Xing 《Chinese Chemical Letters》 2025年第5期283-288,共6页
Achieving artificial simulations of multi-step energy transfer processes and conversions in nature remains a challenge.In this study,we present a three-step sequential energy transfer process,which was constructed thr... Achieving artificial simulations of multi-step energy transfer processes and conversions in nature remains a challenge.In this study,we present a three-step sequential energy transfer process,which was constructed through host-vip interactions between a piperazine derivative(PPE-BPI)with aggregationinduced emission(AIE)and cucurbit[7]uril(CB[7])in water to serve as ideal energy donors.To achieve multi-step sequential energy transfer,we employ three distinct fluorescent dyes Eosin B(EsB),Sulforhodamine 101(SR101),and Cyanine 5(Cy5)as energy acceptors.The PPE-PBI-2CB[7]+EsB+SR101+Cy5 system demonstrates a highly efficient three-step sequential energy transfer mechanism,starting with PPEPBI-2CB[7]and transferring energy successively to EsB,SR101,and finally to Cy5,with remarkable energy transfer efficiencies.More interestingly,with the progressive transfer of energy in the multi-step energy transfer system,the generation efficiency of superoxide anion radical(O_(2)•-)increased gradually,which can be used as photocatalysts for selectively photooxidation of N-phenyltetrahydroisoquinoline in an aqueous medium with a high yield of 86%after irradiation for 18 h.This study offers a valuable investigation into the simulation of multi-step energy transfer processes and transformations in the natural world,paving the way for further research in the field. 展开更多
关键词 LIGHT-HARVESTING sequential energy transfer AIE ROS PHOTOCATALYSIS
原文传递
HyTiFRec:Hybrid Time-Frequency Dual-Branch Transformer for Sequential Recommendation
13
作者 Dawei Qiu Peng Wu +1 位作者 Xiaoming Zhang Renjie Xu 《Computers, Materials & Continua》 2025年第5期1753-1769,共17页
Recently,many Sequential Recommendation methods adopt self-attention mechanisms to model user preferences.However,these methods tend to focus more on low-frequency information while neglecting highfrequency informatio... Recently,many Sequential Recommendation methods adopt self-attention mechanisms to model user preferences.However,these methods tend to focus more on low-frequency information while neglecting highfrequency information,which makes them ineffective in balancing users’long-and short-term preferences.At the same time,manymethods overlook the potential of frequency domainmethods,ignoring their efficiency in processing frequency information.To overcome this limitation,we shift the focus to the combination of time and frequency domains and propose a novel Hybrid Time-Frequency Dual-Branch Transformer for Sequential Recommendation,namely HyTiFRec.Specifically,we design two hybrid filter modules:the learnable hybrid filter(LHF)and the window hybrid filter(WHF).We combine these with the Efficient Attention(EA)module to form the dual-branch structure to replace the self-attention components in Transformers.The EAmodule is used to extract sequential and global information.The LHF andWHF modules balance the proportion of different frequency bands,with LHF globally modulating the spectrum in the frequency domain and WHF retaining frequency components within specific local frequency bands.Furthermore,we use a time domain residual information addition operation in the hybrid filter module,which reduces information loss and further facilitates the hybrid of time-frequency methods.Extensive experiments on five widely-used real-world datasets show that our proposed method surpasses state-of-the-art methods. 展开更多
关键词 sequential recommendation frequency domain efficient attention
在线阅读 下载PDF
Enhancing diagnostic accuracy:Role of stomach-specific serum biomarkers in real-world risk-based sequential screening for malignant gastric lesions
14
作者 Yanna Chi Hongrui Tian +12 位作者 Chao Shi Zhen Liu Xue Li Miao Zhang Jun Liu Xianmei Chen Wenlei Yang Yaqi Pan Huanyu Chen Mengfei Liu Shengjuan Hu Zhonghu He Yang Ke 《Chinese Journal of Cancer Research》 2025年第2期154-164,共11页
Objective:A risk-based sequential screening strategy,from questionnaire-based assessment to biomarker measurement and then to endoscopic examination,has the potential to enhance gastric cancer(GC)screening efficiency.... Objective:A risk-based sequential screening strategy,from questionnaire-based assessment to biomarker measurement and then to endoscopic examination,has the potential to enhance gastric cancer(GC)screening efficiency.We aimed to evaluate the ability of five common stomach-specific serum biomarkers to further enrich high-risk individuals for GC in the questionnaire-identified high-risk population.Methods:This study was conducted based on a risk-based screening program in Ningxia Hui Autonomous Region,China.We first performed questionnaire assessment involving 23,381 individuals(7,042 outpatients and 16,339 individuals from the community),and those assessed as“high-risk”were then invited to participate in serological assays and endoscopic examinations.The serological biomarker model was derived based on logistic regression,with predictors selected via the Akaike information criterion.Model performance was evaluated by the area under the receiver operating characteristic curve(AUC).Results:A total of 2,011 participants were ultimately included for analysis.The final serological biomarker model had three predictors,comprising pepsinogenⅠ(PGI),pepsinogenⅠ/Ⅱratio(PGR),and anti-Helicobacter pylori immunoglobulin G(anti-H.pylori IgG)antibodies.This model generated an AUC of 0.733(95%confidence interval:0.655-0.812)and demonstrated the best discriminative ability compared with previously developed serological biomarker models.As the risk cut-off value of our model rose,the detection rate increased and the number of endoscopies needed to detect one case decreased.Conclusions:PGI,PGR,and anti-H.pylori Ig G could be jointly used to further enrich high-risk individuals for GC among those selected by questionnaire assessment,providing insight for the development of a multi-stage riskbased sequential strategy for GC screening. 展开更多
关键词 Diagnostic model gastric cancer sequential screening serological biomarker
暂未订购
Recent advances in phosphine-mediated sequential annulations
15
作者 Xuling Pan Wei Cai You Huang 《Chinese Chemical Letters》 2025年第5期32-51,共20页
Polycyclic compounds are widely found in natural products and drug molecules with important biological activities,which attracted the attention of many chemists.Phosphine-catalyzed nucleophilic addition is one of the ... Polycyclic compounds are widely found in natural products and drug molecules with important biological activities,which attracted the attention of many chemists.Phosphine-catalyzed nucleophilic addition is one of the most powerful tools for the construction of various cyclic compounds with the advantages of atom economy,mild reaction conditions and simplicity of operation.Allenolates,Morita−Baylis−Hillman(MBH)alcohols and their derivatives(MBHADs),electron-deficient olefins and alkynes are very efficient substrates in phosphine mediated annulations,which formed many phosphonium species such asβ-phosphonium enolates,β-phosphonium dienolates and vinyl phosphonium ylides as intermediates.This review describes the reactivities of these phosphonium zwitterions and summarizes the synthesis of polycycle compounds through phosphine-mediated intramolecular and intermolecular sequential annulations.Thus,a systematic summary of the research process based on the phosphine-mediated sequential annulations of allenolates,MBH alcohols and MBHADs,electron-deficient olefins and alkynes are presented in Chapters 2-6,respectively. 展开更多
关键词 Phosphine catalysis sequential annulations Polycyclic compounds Synthetic methods
原文传递
Linking Filial Piety to Adolescent Autonomy:The Sequential Mediating Roles of Depression and Well-Being in Taiwan region of China University Students
16
作者 Yao-Chung Cheng Wei-Sho Ho +2 位作者 Shu-Hua Lin Kai-Jie Chen Angel Hii 《International Journal of Mental Health Promotion》 2025年第8期1181-1202,共22页
Background:Recent scholarly attention has increasingly focused on filial piety beliefs'impact on youth's psychological development.However,the mechanisms by which filial piety indirectly influences adolescent ... Background:Recent scholarly attention has increasingly focused on filial piety beliefs'impact on youth's psychological development.However,the mechanisms by which filial piety indirectly influences adolescent autonomy through depression and well-being remain underexplored.This study aimed to test a sequential mediation model among filial piety beliefs,depression,well-being,and autonomy in Taiwan region of China university students.Methods:A total of 566 Taiwan region of China undergraduate and graduate students,comprising 390 females and 176 males,and including 399 undergraduates and 167 graduate students,were recruited through convenience sampling.Data were collected via an online questionnaire.Validated instruments were employed,including the Filial Piety Scale(FPS),the Center for Epidemiological Studies Depression Scale(CES-D),the Chinese Well-being Inventory(CHI),and the Adolescent Autonomy Scale-Short Form(AAS-SF).Statistical analyses included group comparisons,correlation analyses,and structural equation modeling to examine the hypothesized relationships and mediation effects.Results:The results revealed that filial piety beliefs exerted a significant positive impact on adolescent autonomy,with depression and well-being serving as key mediators in this relationship.A sequential mediation effect was confirmed through structural equation modeling(β=0.052,95%CI[0.028,0.091]),with good model fit indices(x^(2)/df=4.25,RMSEA=0.076,CFI=0.968),supporting the hypothesized pathway from filial piety to autonomy via depression and well-being.In terms of demographic differences,male students showed significantly higher autonomy than females(p<0.001);students from single-parent families reported significantly higher depression levels than those from two-parent families(p<0.05);and graduate students exhibited significantly higher autonomy and well-being than undergraduates(p<0.05).Conclusions:These findings underscore not only the importance of filial piety beliefs for developing youth autonomy but also the critical role that mental health factors,such as depression and well-being,play in this process.The study concludes with a discussion of both theoretical implications and practical recommendations.These include strategies to foster reciprocal filial piety,strengthen parent-child relationships,and promote mental health.Additionally,the study outlines its limitations and proposes directions for future research. 展开更多
关键词 Filial piety adolescent autonomy DEPRESSION WELL-BEING sequential mediation model
在线阅读 下载PDF
A Hierarchical-Based Sequential Caching Scheme in Named Data Networking
17
作者 Zhang Junmin Jin Jihuan +3 位作者 Hou Rui Dong Mianxiong Kaoru Ota Zeng Deze 《China Communications》 2025年第5期48-60,共13页
Named data networking(NDNs)is an idealized deployment of information-centric networking(ICN)that has attracted attention from scientists and scholars worldwide.A distributed in-network caching scheme can efficiently r... Named data networking(NDNs)is an idealized deployment of information-centric networking(ICN)that has attracted attention from scientists and scholars worldwide.A distributed in-network caching scheme can efficiently realize load balancing.However,such a ubiquitous caching approach may cause problems including duplicate caching and low data diversity,thus reducing the caching efficiency of NDN routers.To mitigate these caching problems and improve the NDN caching efficiency,in this paper,a hierarchical-based sequential caching(HSC)scheme is proposed.In this scheme,the NDN routers in the data transmission path are divided into various levels and data with different request frequencies are cached in distinct router levels.The aim is to cache data with high request frequencies in the router that is closest to the content requester to increase the response probability of the nearby data,improve the data caching efficiency of named data networks,shorten the response time,and reduce cache redundancy.Simulation results show that this scheme can effectively improve the cache hit rate(CHR)and reduce the average request delay(ARD)and average route hop(ARH). 展开更多
关键词 hierarchical router named data networking sequential caching
在线阅读 下载PDF
基于ICP-AES的冶金工业钼铁原料硼元素检测研究
18
作者 袁宏甦 《山西冶金》 2025年第8期42-43,46,共3页
为了对冶金工业中钼铁硼元素进行有效检测,采用感耦合等离子体原子发射光谱法检测原料中的硼元素,分析不同溶解剂硝酸以及分析普波长对检测精度的影响。结果表明,当分析普波长设置为249 nm时,检测元素波峰平滑且峰形清晰。在样品溶解分... 为了对冶金工业中钼铁硼元素进行有效检测,采用感耦合等离子体原子发射光谱法检测原料中的硼元素,分析不同溶解剂硝酸以及分析普波长对检测精度的影响。结果表明,当分析普波长设置为249 nm时,检测元素波峰平滑且峰形清晰。在样品溶解分析中,硝酸容量为8 mL时,硼检测质量分数接近0.0022%。最后在检测精度以及准确度实验分析中,研究技术检测硼质量分数相对标准偏差控制在4%以内,且回收率最高为101.2%,表现出了优异检测效果。该技术在冶金工业中具有良好应用效果,可为工业原材料检测提供技术支持。 展开更多
关键词 icp-aes 钼铁 检测 硼检测
在线阅读 下载PDF
Achieving 20%Toluene‑Processed Binary Organic Solar Cells via Secondary Regulation of Donor Aggregation in Sequential Processing
19
作者 Yufei Wang Chuanlin Gao +15 位作者 Wen Lei Tao Yang Zezhou Liang Kangbo Sun Chaoyue Zhao Lu Chen Liangxiang Zhu Haoxuan Zeng Xiaokang Sun Bin He Hanlin Hu Zeguo Tang Mingxia Qiu Shunpu Li Peigang Han Guangye Zhang 《Nano-Micro Letters》 2025年第9期75-93,共19页
Sequential processing(SqP)of the active layer offers independent optimization of the donor and acceptor with more targeted solvent design,which is considered the most promising strategy for achieving efficient organic... Sequential processing(SqP)of the active layer offers independent optimization of the donor and acceptor with more targeted solvent design,which is considered the most promising strategy for achieving efficient organic solar cells(OSCs).In the SqP method,the favorable interpenetrating network seriously depends on the fine control of the bottom layer swelling.However,the choice of solvent(s)for both the donor and acceptor have been mostly based on a trial-and-error manner.A single solvent often cannot achieve sufficient yet not excessive swelling,which has long been a difficulty in the high efficient SqP OSCs.Herein,two new isomeric molecules are introduced to fine-tune the nucleation and crystallization dynamics that allows judicious control over the swelling of the bottom layer.The strong non-covalent interaction between the isomeric molecule and active materials provides an excellent driving force for optimize the swelling-process.Among them,the molecule with high dipole moment promotes earlier nucleation of the PM6 and provides extended time for crystallization during SqP,improving bulk morphology and vertical phase segregation.As a result,champion efficiencies of 17.38%and 20.00%(certified 19.70%)are achieved based on PM6/PYF-T-o(all-polymer)and PM6/BTP-eC9 devices casted by toluene solvent. 展开更多
关键词 Organic solar cells Non-halogen solvent sequential processing Secondary nucleation Stability
在线阅读 下载PDF
Smart gradient coating suitable for bone growth prepared on plasma-electrolytically oxidised Mg and its sequential degradation behaviour
20
作者 Jiaping Han Kai Fu +6 位作者 Zhiqiang Jiang Hao Zhang Hongshan San Hui Chen Xiaopeng Lu Carsten Blawert Mikhail.L.Zheludkevich 《Journal of Magnesium and Alloys》 2025年第1期356-378,共23页
A gradient coating containing collagen and inorganic strontium/calcium phosphate(Sr/CaP)was fabricated on plasma-electrolytically oxidised magnesium via one-step cathodic electrodeposition.First,Sr-doped dicalcium pho... A gradient coating containing collagen and inorganic strontium/calcium phosphate(Sr/CaP)was fabricated on plasma-electrolytically oxidised magnesium via one-step cathodic electrodeposition.First,Sr-doped dicalcium phosphate dihydrate and hydroxyapatite(DCPD and HA)was deposited,followed by a collagen/CaP layer.The morphological evolution,sequential degradation behaviour,and in vitro bio-properties of the coatings were investigated.The incorporation of collagen remarkably refined the morphology of the CaP,and a more aggregated nano-spherical morphology was observed with increasing collagen concentration.Sr could partially replace Ca in the CaP crystals.Collagen combined with CaP formed a relatively stable skeletal frame,which provided sufficient barrier properties and more sites for the re-precipitation of bone tissue,as well as a more promising proliferation and differentiation ability of osteoblasts.A gradient coating that matches the requirements of bone growth at various periods is suggested for implantation. 展开更多
关键词 Biomedical magnesium alloys Gradient coating sequential degradation Barrier property Bone formation BIOCOMPATIBILITY
在线阅读 下载PDF
上一页 1 2 250 下一页 到第
使用帮助 返回顶部