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Journal of Rare Earths 2018年第3期36卷 231-237页

作者： Xiangzhou Zhang Yongjin Li Rui Hu Zuyuan Xu Jianbei qiu Zhengwen Yang Zhiguo Song School of Materials Science and Engineering Kunming University of Science and Technology School of Materials Science and Engineering Sun Yat-sen University

BiOCl crystal shows potential as efficient optical host due to its special layered structure. Here,the luminescence properties of the Er^3＋/Sm^3＋ co-doped BiOCl phosphors as single-phase phosphors were reported. Upon near ultraviolet excitation（NUV, 380 nm corresponding the ^4 I15/2→ ^4 G11/2 transition of Er^3＋ ions）, the phosphors exhibit the efficient characteristic emissions of Er^3＋ and Sm^3＋ ions simultaneously. The energy transfer（ET） from Er^3＋ to Sm^3＋ ions in the layered crystals has been validated by the variation of emission intensities and decay lifetimes respectively, which is ascribed to be a dipoledipole interaction. By virtue of the ET behavior and increasing Sm^3＋ ion concentration, the enhancing emission intensity of Sm^3＋ and the tunability of emission color from yellowish-green（0.318, 0.420） to white（0.343, 0.347） are realized. The results of our work indicate that the Er^3＋/Sm^3＋ co-doped BiOCI phosphor has a promising application serving as single component white emitting phosphors for NUV excited WLEDs.

关键词： BiOCl Er^3+ Sm^3+ Color tunable Photoluminescence Energy transfer

Attack Behavior Extraction Based on Heterogeneous Cyberthreat Intelligence and Graph Convolutional Networks

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Computers, Materials & Continua 2023年第1期74卷 235-252页

作者： Binhui Tang Junfeng Wang Huanran qiu Jian Yu Zhongkun Yu Shijia Liu School of Cyber Science and Engineering Sichuan UniversityChengdu610065China College of Computer Science Sichuan UniversityChengdu610065China Jincheng College of Sichuan University Chengdu610065China Institute for Infocomm Research A∗STAR SingaporeSingapore

The continuous improvement of the cyber threat intelligence sharing mechanism provides new ideas to deal with Advanced Persistent Threats(APT).Extracting attack behaviors,i.e.,Tactics,Techniques,Procedures(TTP)from Cyber Threat Intelligence(CTI)can facilitate APT actors’profiling for an immediate ***,it is difficult for traditional manual methods to analyze attack behaviors from cyber threat intelligence due to its heterogeneous *** on the Adversarial Tactics,Techniques and Common Knowledge(ATT&CK)of threat behavior description,this paper proposes a threat behavioral knowledge extraction framework that integrates Heterogeneous Text Network(HTN)and Graph Convolutional Network(GCN)to solve this *** leverages the hierarchical correlation relationships of attack techniques and tactics in the ATT&CK to construct a text network of heterogeneous cyber threat *** the help of the Bidirectional EncoderRepresentation fromTransformers(BERT)pretraining model to analyze the contextual semantics of cyber threat intelligence,the task of threat behavior identification is transformed into a text classification task,which automatically extracts attack behavior in CTI,then identifies the malware and advanced threat *** experimental results show that F1 achieve 94.86%and 92.15%for the multi-label classification tasks of tactics and *** the experiment to verify the method’s effectiveness in identifying the malware and threat actors in APT *** F1 for malware and advanced threat actors identification task reached 98.45%and 99.48%,which are better than the benchmark model in the experiment and achieve state of the *** model can effectivelymodel threat intelligence text data and acquire knowledge and experience migration by correlating implied features with a priori knowledge to compensate for insufficient sample data and improve the classification performance and recognition ability of threat behavior in text.

关键词： Attack behavior extraction cyber threat intelligence(CTI) graph convolutional network(GCN) heterogeneous textual network(HTN)

Selective Dealkenylative Functionalization of Styrenes via C-C Bond Cleavage

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Research 2020年第1期2020卷 1420-1428页

作者： Jianzhong Liu Jun Pan Xiao Luo Xu qiu Cheng Zhang Ning Jiao State Key Laboratory of Natural and Biomimetic Drugs Peking University100191 BeijingChina State Key Laboratory of Organometallic Chemistry Chinese Academy of SciencesShanghai 200032China

As a readily available feedstock,styrene with about 25 million tons of global annual production serves as an important building block and organic synthon for the synthesis of fine chemicals,polystyrene plastics,and ***,in the past decades,many direct transformations of this costless styrene feedstock were disclosed for the preparation of high-value chemicals,which to date,generally performed on the functionalization of styrenes through the allylic C-H bond,C(sp2)-H bond,or the C=C double bond ***,the dealkenylative functionalization of styrenes via the direct C-C single bond cleavage is so far challenging and still ***,we report the novel and efficient C-C amination and hydroxylation reactions of styrenes for the synthesis of valuable aryl amines and phenols via the site-selective C(Ar)-C(alkenyl)single bond *** chemistry unlocks the new transformation and application of the styrene feedstock and provides an efficient protocol for the late-stage modification of substituted styrenes with the site-directed dealkenylative amination and hydroxylation.

关键词： styrene cleavage synthesis

Two new olean-type triterpene fatty esters from Scorzonera mongolica

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Chinese Chemical Letters 2007年第6期18卷 708-710页

作者： Bin Wang Guo Qiang Li Pei Ju qiu Hua Shi Guan Institute of Marine Drugs and Food of Ocean University of China Qingdao 266003 China

Two new triterpene fatty esters, 3β-tetradecanoyl moradiol 1 and 3β-dodecanoyl moradiol 2, were isolated from Scorzonera mongolica. Their structures were elucidated as 3β-tetradecanoyloxy-28-hydroxylolean-18-ene and 3β-dodecanoyl-28-hydroxyl-olean-18-ene on the basis of IR, MS, 1D NMR and extensive 2D NMR spectroscopic analyses.

关键词： Scorzonera mongolica Moradiol Triterpene fatty esters

Quality of experience evaluation of HTTP video streaming based on user interactive behaviors

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The Journal of China Universities of Posts and Telecommunications 2017年第3期24卷 24-32页

作者： Li Wenjing Yu Peng Wang Ruiyi Feng Lei Dong Ouzhou qiu Xuesong Institute of Network Technology Beijing University of Posts and Telecommunications

User interactive behaviors play a dual role during the hypertext transfer protocol （HTTP） video service： reflection and influence. However, they are seldom taken into account in practices. To this end, this paper puts forward the user interactive behaviors, as subjective factors of quality of experience （QoE） from viewer level, to structure a comprehensive multilayer evaluation model based on classic network quality of service （QoS） and application QoS. First, dual roles of user behaviors are studied and the characteristics are extracted where the user experience is correlated with user interactive behaviors. Furthermore, we categorize QoE factors into three dimensions and build the metric system. Then we perform the subjective tests and investigate the relationships among network path quality, user behaviors, and QoE. Ultimately, we employ the back propagation neural network （BPNN） to validate our analysis and model. Through the simulation experiment of mathematical and BPNN, the dual effects of user interaction behaviors on the reflection and influence of QoE in the video stream are analyzed, and the QoE metric system and evaluation model are established.

关键词： HTTP video streaming QoE user interactive behaviors BPNN

Syntheses and Bioactivities of 4-Ar-2-oxo-glutaric Acids

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Chemical Research in Chinese Universities 2007年第3期23卷 284-288页

作者： CHEN qiu-yun ZHANG Rong-xian LIU Qing-shan Schofield Christopher Institute of Chemistry and Engineering Jiangsu University Zhenjiang 212013 P. R. China CRL University of Oxford South Parks Road Oxford OX1 3QY UK

Fourteen novel compounds were synthesized and characterized by using NMR and ESI-MS methods. The bioactivities of the four novel 4-Ar-2-oxo-glutaric acids were studied by using the LC-MS method. The experimental results show that 3-nitrobenzyl-2-oxo-glutaric acid is a mild inhibitor for the hydroxylation reaction catalyzed by PHD2. The decarboxylated peak for 3-fluorobenzyl-2-oxo-glutaric acid was observed by using the negative LC-MS method, indicating that it can be used as a mild cosubstrate to replace 2-OG, but this is possible only in the presence of the prime peptide CODD 19 mer.

关键词： 2-Oxo-glutaric acid Bioactivity Inhibitor Synthesis

Ablative behavior and mechanism of SiC_(f) /SiBCZr composites prepared by PIP process

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Journal of Advanced Ceramics 2024年第1期13卷 124-134页

作者： Mingwei Chen Yuliang Zhao Haipeng qiu Shijian Liu Weijie Xie Yi Chen Qiyue Zhang AVIC Manufacturing Technology Institute Beijing 100130China

SiC_(f)/SiBCZr composites were prepared by polymer precursor impregnation and pyrolysis process with near stoichiometric ratio SiC fiber preform as reinforcement phase and SiBCZr multiphase ceramic precursor as impregnating *** results highlighted that the SiC_(f)/SiBCZr composites exhibited excellent ablative properties after ablative tests at 1200℃/3600 s and 1400℃/3600 s,and the strength retention rates of the composites reached 90%and 85%,*** was mainly due to the liquid sealing effect of the ablative products represented by B2O_(3) and SiO_(2)∙B_(2)O_(3),which inhibited the ablative reaction by reducing the diffusion rate of the oxidation medium,and the solid pinning effect of the substances represented by SiO_(2),ZrO_(2),and ZrSiO_(4),which could play high viscosity and high strength characteristics to improve anti-erosion *** above-mentioned SiC_(f)/SiBCZr composites with corrosion resistance,oxidation resistance,and ablative resistance provided a solid material foundation and technical support for the development of reusable spacecraft hot-end components.

关键词： near stoichiometric ratio SiC fiber SiC_(f)/SiBCZr composite liquid sealing effect solid pinning effect

Concentrations and isotopic characteristics of atmospheric reactive nitrogen around typical sources in Beijing,China

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Journal of Arid Land 2016年第6期8卷 910-920页

作者： LIU Jieyun ZHANG Ying LIU Xuejun TANG Aohan qiu Husen ZHANG Fusuo Center for Resources Environment and Food SecurityKey Laboratory of Plant-Soil InteractionsMinistry of EducationCollege of Resources & Environmental SciencesChina Agricultural University School of Environment and Surveying Engineering Suzhou University Changsha Research Station for Agricultural Environment Monitoring & Key Laboratory of Agro-Ecological Processes in Subtropical Region Institute of Subtropical AgricultureChinese Academy of Sciences

With rapid economic growth in China, anthropogenic reactive nitrogen （Nr） emissions have more than doubled over the last two or three decades. Atmospheric Nr pollution is an environmental concern in China especially in megacities such as Beijing. In order to identify the impact of emission sources on atmospheric Nr pollution, we measured atmospheric Nr concentrations and their isotopic composition （δ15N） dynamics at three typical sites： landfill, pig farm and road traffic sites in Beijing from April 2010 to March 2011. Passive samplers were used for monitoring ammonia （NH3） and nitrogen dioxide （NO2）, two major Nr species, while their δ15N values were measured by a diffusion method combined with mass spectrometer approach. The raw water pool of the landfill and fattening house of the pig farm were important NH3 sources with mean NH3 concentrations being 2,829 and 2,369 μg/m3, respectively, while the road traffic site was a minor NH3 source （10.6 μg/m3）. NH3 concentrations at sites besides the landfill and roads were high in summer and low in winter due to the annual variation of temperature and the change of emission source intensity. In contrast, the NH3 concentrations inside the pig farm house were high in winter and low in summer, for the barn windows were open in summer and closed in winter. The mean NO2 concentrations were 89.8, 32.9 and 23.0 μg/m3 at the road traffic, the landfill and pig farm sites, respectively. Due to vehicle fuel combustion, NO2 concentration at the road traffic was the highest among the three sources, and the road traffic was a main NO2 emission source. PM10, pNH4＊ and pNO3- concentrations in particulate matter were higher in summer than in winter （except PM10 for the pig farm）. The δ15NH3 values ranged from -19.14‰ to 7.82‰, with an average of-0.05‰ for the landfill site, and the lowest values were observed in June and July. The δ15NH3 values for the pig farm site ranged from -29.78‰ to-14.05‰ with an average of-24.51‰, and the 515NH3 va

关键词： atmospheric reactive N pollution emission sources NH3 NO2 particulate matter

Identification of MicroRNA Precursors with Support Vector Machine and String Kernel

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Genomics, Proteomics & Bioinformatics 2008年第2期6卷 121-128页

作者： Jian-Hua Xu Fei Li qiu-Feng Sun Department of Computer Science Nanjing Normal University Nanjing 210097 China Department ofEntomology Nanjing Agricultural University Nanjing 210095 China

MicroRNAs （miRNAs） are one family of short （21-23 nt） regulatory non-coding RNAs processed from long （70-110 nt） miRNA precursors （pre-miRNAs）. Identifying true and false precursors plays an important role in computational identification of miRNAs. Some numerical features have been extracted from precursor sequences and their secondary structures to suit some classification methods; however, they may lose some usefully discriminative information hidden in sequences and structures. In this study, pre-miRNA sequences and their secondary structures are directly used to construct an exponential kernel based on weighted Levenshtein distance between two sequences. This string kernel is then combined with support vector machine （SVM） for detecting true and false pre-miRNAs. Based on 331 training samples of true and false human pre-miRNAs, 2 key parameters in SVM are selected by 5-fold cross validation and grid search, and 5 realizations with different 5-fold partitions are executed. Among 16 independent test sets from 3 human, 8 animal, 2 plant, 1 virus, and 2 artificially false human pre-miRNAs, our method statistically outperforms the previous SVM-based technique on 11 sets, including 3 human, 7 animal, and 1 false human pre-miRNAs. In particular, premiRNAs with multiple loops that were usually excluded in the previous work are correctly identified in this study with an accuracy of 92.66%.

关键词： string kernel support vector machine microRNA precursor weighted Levenshteindistance

Detrital K-feldspar^(40)Ar/^(39)Ar Ages:Source Constraints of the Lower Miocene Sandstones in the Pearl River Mouth Basin,South China Sea

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Acta Geologica Sinica(English Edition) 2012年第2期86卷 383-392页

作者： LIU Zaisheng SHI Hesheng ZHU Junzhang qiu Huaning ZHANG Zhilin YUN Jianbing CNOOC China Limited Shenzhen Shenzhen 518067China State Key Laboratory of Isotopic Geochemistry Guangzhou Institute of GeochemistryChinese Academy of SciencesGuangzhou 510640China Hailaer Petroleum Exploration and Development Headquarters PetroChina Daqing Oilfield Company Ltd.Hailar 021000China

The South China Sea began to outspread in the Oligocene. A great quantity of terraneous detritus was deposited in the northern continental shelf of the sea, mostly in Pearl River Mouth Basin, which constituted the main paleo-Pearl River Delta. The delta developed for a long geological time and formed a superimposed area. Almost all the oil and gas fields of detrital rock reservoir distribute in this delta. Thirty-three oil sandstone core samples in the Zhujiang Formation, lower Miocene （23-16 Ma）, were collected from nine wells. The illite samples with detrital K feldspar （Kfs） separated from these sandstone cores in four sub-structural belts were analysed by the high-precision 40Ar/39Ar laser stepwise heating technique. All 33 illite 40Ar/39Ar data consistently yielded gradually rising age spectra at the low-temperature steps until reaching age plateaus at mid-high temperature steps. The youngest ages corresponding to the beginning steps were interpreted as the hydrocarbon accumulation ages and the plateau ages in mid-high temperature steps as the contributions of the detrital feldspar representing the ages of the granitic parent rocks in the provenances. The ages of the detrital feldspar from the Zhujiang Formation in the four sub-structural belts were different：（1） the late Cretaceous ages in the Lufeng 13 fault structural belt; （2） the late Cretaceous and early Cretaceous-Jurassic ages in the Huizhou 21 buried hill-fault belt; （3） the Jurassic and Triassic ages in the Xijiang 24 buried hill-fault belt; and （4） the early Cretaceous - late Jurassic ages in the Panyu 4 oil area. These detrital feldspar 4~Ar/39Ar ages become younger and younger from west to east, corresponding to the age distribution of the granites in the adjacent Guangdong Province, Southern China.

关键词： Illite detrital K feldspar 40Ar/39Ar dating parent rock sandstone reservoir Pearl River Mouth Basin