|
|
|
题名
|
作者
|
年代
|
出处
|
被引量
|
| 1 | Geochronology and Petrogenesis of Triassic High-K Calc-Alkaline Granodiorites in the East Kunlun Orogen,West China:Juvenile Lower Crustal Melting during Post-Collisional Extension显示文摘This study reports zircon U-Pb and Hf isotopes and whole-rock elemental data for granodiorites from the East Kunlun orogen. The zircon U-Pb dating defines their crystallization age of 235 Ma. The rocks are characterized by high-K calc-alkaline, magnesian and metaluminous with(K_2O+Na_2O)=6.38 wt.%–7.01 wt.%, Mg#=42–50 [Mg#=100×molar Mg/(Mg+Fe OT)], A/CNK=0.92–0.98, coupled with high εHf(t) values from-0.65 to-1.80. The rocks were derived from partial melting of a juvenile mafic crustal source within normal crust thickness. The juvenile lower crust was generated by mixing lithospheric mantle-derived melt(55%–60%) and supracrustal melt(40%–45%) during the seafloor subduction. Together with available data from the East Kunlun, it is proposed that the studied Middle Triassic granodiorites were formed in post-collisional extension setting, in which melting of the juvenile lower crust in response to the basaltic magma underplating resulted in the production of high-K granodioritic melts. | Fuhao Xiong Changqian Ma Hong’an Jiang Hang Zhang | 2016 | Journal of Earth Science2016，27，3： | 16 |
| 2 | Tianwen-1 MINPA observations in the solar wind显示文摘The Mars Ion and Neutral Particle Analyzer(MINPA)is one of the three scientific instruments onboard the Tianwen-1 orbiter to investigate the Martian space environment.During Tianwen-1’s transfer orbit to Mars,the MINPA was switched on to measure the solar wind ions.Here,we present the first results of the MINPA observations in the solar wind.During cruise,nearly half of the MINPA ion field-of-view(FOV)was blocked by the lander capsule;thus only the solar-wind ions with azimuthal speeds pointing towards the unblocked FOV sectors could be detected.We perform a detailed comparison of the MINPA’s solar wind observations with data from Earth-based missions when MINPA reached its count-rate peak,finding a general consistency of the ion moments between them.The blocking effect due to the lander is evaluated quantitatively under varying solar-wind velocity conditions.Despite the blocking effect,the MINPA’s solar wind measurements during the transfer orbit suggest a good performance. | AiBing Zhang LingGao Kong WenYa Li Lei Li BinBin Tang ZhaoJin Rong Yong Wei JiJie Ma YiTeng Zhang LiangHai Xie YuXian Wang JianSen He Bin Liu WenJing Wang Bin Su JiaWei Li Xu Tan Fang Wang TaiFeng Jin FuHao Qiao Peter Wurz Yan Zhu YunFei Bai YiRen Li XinBo Zhu YueQiang Sun YongLiao Zou Chi Wang | 2022 | Earth and Planetary Physics2022，6，1： | 5 |
| 3 | Geology, Geochronology, and Hf Isotopic Composition of the Pha Lek Fe Deposit, Northern Laos: Implications for Early Permian Subduction-Related Skarn Fe Mineralization in the Truong Son Belt显示文摘The Truong Son metallogenic belt in central Laos and Vietnam is an important Fe-Cu-Sn-Au polymetallic ore district. The Pha Lek Fe deposit is closely related to Late Carboniferous– Early Permian I-type granitic magmatism, and contains >50 Mt @ 45% to 50% of Fe ore. Ore minerals occur mainly as magnetite and hematite in the skarn alteration zone between a granitic pluton and metamorphosed Middle–Upper Devonian carbonates. The granitic pluton comprises granodiorite and granite, with zircon U-Pb dating indicating synchronous emplacement at 288.2±1.3 and 284.9±1.2 Ma, respectively. Zircons from these granitoids have ε_(Hf)(t) values of 2.9–11.2 and relatively young TDM2 ages(<1.0 Ga), indicating an origin by partial melting of depleted mafic crust or magma mixing. Previous studies have shown that these granitoids have high Y, Yb, and K_2O contents, and low Sr and Na_2O contents, which are interpreted as the melting of mafic continental crust. Pyrite of the main mineralization stage yields an ^(187)Re/^(188)Os-^(187)Os/^(188)Os isochron age of 287±17 Ma, indicating that mineralization is associated with Pha Lek granitic magmatism. A Late Carboniferous–Early Permian subduction-related skarn-type Fe mineralization model is proposed for the Pha Lek deposit. More evidence is needed to verify a hypothesis of volcanic overprinting during Late Triassic post-collisional extension. | Lin Hou Shusheng Liu Linnan Guo Fuhao Xiong Chao Li Meifeng Shi Qiming Zhang Siwei Xu Songyang Wu | 2019 | Journal of Earth Science2019，30，1： | 2 |
| 4 | Inactive Al^(3+)-doped La(CoCrFeMnNiAl_(x))_(1/(5+x))O_(3)high-entropy perovskite oxides as high performance supercapacitor electrodes显示文摘A series of high-entropy perovskite oxides(HEPOs)La(CoCrFeMnNiAl_(x))_(1/(5+x))O_(3-δ)(x=0.4,0.5,0.6,and 0.7)have been synthesized by coprecipitation method combined with calcination process and explored as electrodes for supercapacitors.The crystal structure,microstructure,and elemental composition of HEPOs were investigated by X-ray diffraction(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM),and energy-dispersive X-ray spectroscopy(EDS)in detail.The electrochemical properties of HEPOs as supercapacitor electrodes were elucidated.The specific capacitances of HEPOs(x=0.4,0.5,0.6,and 0.7)are 281.84,353.65,325.60,and 259.30 F/g at the current density of 1 A/g,respectively.After 2000 cycles,the specific capacitances of HEPOs(x=0.4,0.5,0.6,and 0.7)remain 85.01%,88.61%,86.37%,and 91.25%,respectively.Such outstanding electrochemical properties can be attributed to the entropy-stabilized structure caused by mixed six cations in B-site and the Al^(3+)-doping suppressing active ion aggregation during charge-discharge process.This research highlights the potential of HEPOs as electrodes for supercapacitors. | Meng GUO Yufeng LIU Fengnian ZHANG Fuhao CHENG Chufei CHENG Yang MIAO Feng GAO Jun YU | 2022 | Journal of Advanced Ceramics2022，11，5： | 2 |
| 5 | Preparation and electrical conductivity of(Zr,Hf,Pr,Y,La)O high entropy fluorite oxides显示文摘A series of compositionally complex fluorite oxides(CCFOs)were prepared by ball milling the mixture of ZrO_(2),HfO_(2),Y_(2)O_(3),La_(2)O_(3),and Pr_(6)O_(11)followed by conventional solid-state sintering.Both XRD and TG-DSC results demonstrated that single-phase(Zr_(0.2)Hf_(0.2)Pr_(0.2)Y_(0.2)La_(0.2))O_(2-)δwas formed at 1400°C.Elements in bulk ceramic were uniformly distributed without evident accumulation according to SEM-EDS pictures.TEM results revealed that polycrystalline ceramic powder was assignable to cubic Fm-3m fluorite structure.The electrical conductivity(σ)was measured via EIS technology and activation energy(E_(a))of CCFOs was calculated in Arrhenius plots.In the temperature range of 300-750°C,CCFOs preserved the same conduction mechanism and(Zr_(0.1667)Hf_(0.1667)Pr_(0.1667)Y_(0.25)La_(0.25))O_(2-)δpossessed higherσand lower E_(a) than other high entropy fluorite oxides which is related to the incorporation of Pr element or the connection of cation-V_(o) complex. | Fengnian Zhang Fuhao Cheng Chufei Cheng Meng Guo Yufeng Liu Yang Miao Feng Gao Xiaomin Wang | 2022 | Journal of Materials Science & Technology2022，，10： | 2 |
| 6 | Two Contrasting Ophiolites in One Suture Zone: a Case Study from East Kunlun Orogenic Belt, North Tibetan Plateau显示文摘Ophiolites are fragments of upper mantle and oceanic crust(Dewey and Bird,1971;Coleman,1977;Nicolas,1989)that were consisting of mantle peridotites and a suite of magmatic rocks.Importantly,ophiolite suite is the key sign for the boundary between two terranes,and could be produced in varied settings,such as | ZHANG Hang MA Changqian XIONG Fuhao JIANG Hongan LIU Bin GUO Pan | 2015 | Acta Geologica Sinica(English Edition)2015，89，A02： | 2 |
| 7 | In-situ experimental investigation of the influence of structure characteristics on subway-induced building vibrations显示文摘Many types of buildings have been widely constructed in the vicinity of subway lines in China.Normal life and business activities are hampered by excessive subway-induced vibrations.This study aims to determine the influence of structure characteristics on structure-borne vibrations,generally based on experimental results.Vibration measurements were performed in four typical sites in Wuxi,China,involving over-track buildings,along-track buildings,frame structure buildings and a masonry building.Special structure designs like structure transfer floor were also included.Then,the captured data was analyzed in the time domain and the frequency domain.Furthermore,the influence of building location,structure type and structure layout was investigated.Finally,vibrations were evaluated with ISO and Chinese criteria and structure optimization for vibration attenuation was proposed.It is found that over-track buildings are more severely affected than along-track buildings.Higher frequency contents(20‒60 Hz)in over-track buildings and lower frequency contents(0‒10 Hz)in along-track buildings should be seriously considered in vibration control.Weaker structure member joints and lower material strength would be beneficial to over-track buildings while the inverse situation would be beneficial to along-track buildings.The application of structure transfer floor‒generally stiffer structure members and structure discontinuity‒is also beneficial. | Feng Shijin Li Fuhao Zhang Xiaolei Dong Guowei Li Jianping | 2021 | Earthquake Engineering and Engineering Vibration2021，20，3： | 1 |
| 8 | Permian Radiolarians from the A'nyemaqen Mélange Zone in the Huashixia Area of Madoi County,Qinghai Province,Western China,and Their Implications on Regional Tectonism显示文摘The Huashixia area in the Madoi County, Qinghai Province, western China is one of the most important areas for the studies of the formation and evolution of the A'nyemaqen mélange zone due to the well exposed, relatively complete tectonostratigraphic successions. However, the timing and evolutionary process of the A'nyemaqen paleo-ocean has long been poorly understood. Recently, we obtained abundant radiolarians from the siliceous rocks of the Maerzheng Formation of this mélange zone in Huashixia. Total 19 species in 10 radiolarian genera have been identified. They belong mainly to the Albaillellaria, Spumellaria, Entactinaria, and Latentifistularia. Four radiolarian assemblage zones are established, including: the Pseudoalbaillella rhombothoracata, Pseudoalbaillella scalprata, Ruzhencevispongus uralicus, and Follicucullus bipartitus-Follicucullus sp. cf. F. ventricosus zones. Radiolarian faunal correlations suggest a late Artinskian–early Kungurian age and late Capitanian–early Wuchiapingian age for the first two zones from the lower part and the last two zones from the upper parts of the Maerzheng Formation, respectively. All radiolarians are typical of deep water elements living in deep oceans in low latitudes during the Permian. Previously, the radiolarians of Early Carboniferous to Early Permian age and fusulinids of Early–Middle Permian age have also been reported from the A'nyemaqen mélange successions. The combination of the newly found radiolarians with the previously reported faunal and microfloral assemblages as well as radiometric ages obtained from the same stratigraphic units indicates that the A'nyemaqen paleo-ocean may have opened initially during the Early Carboniferous, expanded from the Early–Middle Permian, reached its acme in the early Late Permian, shrunk during the latest Permian to Early Triassic, and eventually was closed in the Middle Triassic. | Zhigang Zhao Xing Huang Xionghua Zhang Bing Yang Zhong-Qiang Chen Fuhao Xiong | 2016 | Journal of Earth Science2016，27，4： | 1 |
| 9 | The origin of maficmicrogranular enclaves and their host granodiorites from East Kunlun,northern Qinghai-Tibet Plateau:Implications for magma mixing during subduction of Paleo-Tethyan lithosphere显示文摘 | Xiong Fuhao Ma Changqian Zhang Jinyang | 2012 | Mineralogy and Petrology2012，104，34： | 1 |
| 10 | Single-cell RNA-sequencing reveals radiochemotherapy-induced innate immune activation and MHC-II upregulation in cervical cancer显示文摘Radiochemotherapy(RCT)is a powerful treatment for cervical cancer,which affects not only malignant cells but also the immune and stromal compartments of the tumor.Understanding the remodeling of the local ecosystem induced by RCT would provide valuable insights into improving treatment strategies for cervical cancer.In this study,we applied single-cell RNA-sequencing to paired pre-and post-RCT tumor biopsies from patients with cervical cancer and adjacent normal cervical tissues.We found that the residual population of epithelial cells post-RCT showed upregulated expression of MHC class II genes.Moreover,RCT led to the accumulation of monocytic myeloid-derived suppressor cells with increased pro-inflammatory features and CD16+NK cells with a higher cytotoxic gene expression signature.However,subclusters of T cells showed no significant increase in the expression of cytotoxic features post-RCT.These results reveal the complex responses of the tumor ecosystem to RCT,providing evidence of activation of innate immunity and MHC-II upregulation in cervical cancer. | Chao Liu Xiaohui Li Qingyu Huang Min Zhang Tianyu Lei Fuhao Wang Wenxue Zou Rui Huang Xiaoyu Hu Cong Wang Xiaoling Zhang Bing Sun Ligang Xing Jinbo Yue Jinming Yu | 2023 | Signal Transduction and Targeted Therapy2023，8，2： | 0 |
| 11 | Network Traffic Clustering with QoS-Awareness显示文摘Network traffic classification is essential in supporting network measurement and management.Many existing traffic classification approaches provide application-level results regardless of the network quality of service(QoS)requirements.In practice,traffic flows from the same application may have irregular network behaviors that should be identified to various QoS classes for best network resource management.To address the issues,we propose to conduct traffic classification with two newly defined QoSaware features,i.e.,inter-APP similarity and intraAPP diversity.The inter-APP similarity represents the close QoS association between the traffic flows that originate from the different Internet applications.The intra-APP diversity describes the QoS variety of the traffic even among those originated from the same Internet application.The core of performing the QoS-aware feature extraction is a Long-Short Term Memory neural network based Autoencoder(LSTMAE).The QoS-aware features extracted by the encoder part of the LSTM-AE are then clustered into the corresponding QoS classes.Real-life data from multiple applications are collected to evaluate the proposed QoS-aware network traffic classification approach.The evaluation results demonstrate the efficacy of the extracted QoS-aware features in supporting the traffic classification,which can further contribute to future network measurement and management. | Jielun Zhang Fuhao Li Feng Ye | 2022 | China Communications2022，19，3： | 0 |
| 12 | Vacancy engineering of oxidized Nb_(2)CTx MXenes for a biased nitrogen fixation显示文摘The artificial nitrogen(N_(2)) reduction reaction(NRR) via electrocatalysis is a newly developed methodology to produce ammonia(NH3) at ambient conditions,but faces the challenges in N_(2)activation and poor reaction selectivity.Herein,Nb-based MXenes are developed to remarkably enhance the NRR activity through the engineering of the stretched 3D structure and oxygen vacancies(VO).The theoretical studies indicate that N_(2)could be initially adsorbed on VOwith an end-on configuration,and the potential determining step might be the first hydrogenation step.The catalysts achieve an NH3production rate of 29.1 μg h^(-1)mg_(cat)^(-1)and excellent Faradic efficiency of 11.5%,surpassing other Nbbased catalysts.The selectivity of NRR is assigned to the unique structure of the catalysts,including(1) the layered graphitic structure for fast electron transfer and active site distribution,(2) the reactive VOfor N_(2)adsorption and activation,and(3) the expanded interlayer space for mass transfer. | Mengzhao Zhang Hanqing Yin Fuhao Jin Jingquan Liu Xuqiang Ji Aijun Du Wenrong Yang Zhen Liu | 2023 | Green Energy & Environment2023，8，4： | 0 |
| 13 | Nutritional,phytochemical and antioxidant properties of 24 mung bean(Vigna radiate L.)genotypes显示文摘This study aimed to investigate the proximate and phytochemicals present in seeds of 24 mung bean(Vigna radiate L.)genotypes from four provinces of China for estimating their nutritional and antioxidant properties.Proximate analysis of mung bean genotypes revealed that starch,protein,fat,ash and water-soluble polysaccharide ranged from 39.54–60.66,17.36–24.89,4.24–12.18,2.78–3.53 and 1.99–2.96 g/100 g respectively.The five principal fatty acids detected in mung beans were stearic acid,palmitic acid,linoleic acid,oleic acid,and linolenic acid.The contents of insoluble-bound phenolic compounds,soluble phenolic compounds,and flavonoids ranged from 0.78 to 1.5 mg GAE g^(-1),1.78 to 4.10 mg GAE g^(-1),and 1.25 to 3.52 mg RE g^(-1),respectively.The black seed coat mung bean genotype M13(Suheilv 1)exhibited highest flavonoid and phenolic contents which showed strong antioxidant activity.Two flavonoids(vitexin and isovitexin)and four phenolic acids(caffeic,syringic acid,p-coumaric,and ferulic acids)were identified by HPLC.Vitexin and isovitexin were the major phenolic compounds in all mung bean genotypes.The content of soluble phenolic compounds had positive correlation with DPPH(r2=0.713)and ABTS(r2=0.665)radical scavenging activities.Principal component analysis indicated that the first two principal components could reflect most details on mung bean with a cumulative contribution rate of 66.1%.Twenty-four mung bean genotypes were classified into four groups based on their phenolic compounds contents and antioxidant activities.The present study highlights the importance of these mung bean genotypes as a source of nature antioxidant ingredient for the development of functional foods or a source of health promoting food. | Fuhao Wang Lu Huang Xingxing Yuan Xiaoyan Zhang Luping Guo Chenchen Xue Xin Chen | 2021 | Food Production, Processing and Nutrition2021，3，1： | 0 |
| 14 | Asymmetric Dearomatization of Electron-Deficient Heteroarenes by a Phosphine-Catalyzed[3+2]Annulation with Vinylcyclopropanes显示文摘Asymmetric dearomatization reactions of various electron-deficient heteroarenes,including benzofurans,benzothiophenes,and indoles,have been described.Through a phosphine-catalyzed[3+2]annulation with vinylcyclopropanes,readily available heteroarene feedstocks undergo smooth dearomatization reactions,delivering a diverse array of valuable chiral cyclopentabenzodihydrofuran and cyclopentaindoline scaffolds in a highly diastero-and enantioselective manner.Notably,the employment of cyclopropanes in phosphine-mediated annulation for the dearomatization of electron-deficient arenes is unknown. | Xuan Dai Fuhao Zhang Lei Dai Yixin Lu | 2023 | CCS Chemistry2023，5，9： | 0 |
| 15 | Proton pitch angle distributions in the Martian induced magnetosphere: A survey of Tianwen-1 Mars Ion and Neutral Particle Analyzer observations显示文摘The pitch angle distributions of ions and electrons can be affected by various processes;thus,they can serve as an important indicator of the physical mechanisms driving the dynamics of space plasmas.From observations from the Mars Ion and Neutral Particle Analyzer onboard the Tianwen-1 orbiter,we calculated the pitch angle distributions of protons in the Martian induced magnetosphere by using information from the magnetohydrodynamically simulated magnetic field,and we statistically analyzed the spatial occurrence pattern of different types of pitch angle distributions.Even though no symmetrical features were seen in the dataset,we found the dominance of the field-aligned distribution type over the energy range from 188 to 6232 eV.Maps of the occurrence rate showed the preferential presence of a trapped-like distribution at the lower altitudes of the surveyed nightside region.Although our results are more or less restricted by the adopted magnetic field,they indicate the complexity of the near-Mars proton pitch angle distributions and infer the possibility of wave–particle interactions in the Martian induced magnetosphere. | TaiFeng Jin BinBin Ni LingGao Kong AiBing Zhang Lei Li Song Fu Xing Cao WenYa Li BinBin Tang LiangHai Xie YiTeng Zhang ShuYue Pang XiaoTong Yun HengLe Du FuHao Qiao LiMin Wang JiJie Ma | 2023 | Earth and Planetary Physics2023，7，5： | 0 |
| 16 | Geochronology and Geochemistry of the Triassic Mafic Complexes from the Western Garzê-Litang Ophiolitic Mélange and Implications for the Melt Evolution of a Continental Margin显示文摘There is a general consensus that most ophiolites on the earth formed above a subduction zone and they often display a characteristic,sequential evolution of MORB to island arc tholeiities(IAT)to bonnites(Dilek et al.,2010,2009;Pearce et al.,2003).However,ophiolites occurred | LIU Bin MA Changqian ZHANG Xin GUO Pan ZHANG Hang XIONG Fuhao | 2015 | Acta Geologica Sinica(English Edition)2015，89，A02： | 0 |
| 17 | A pair of G-type lectin receptor-like kinases modulates nlp20-mediated immune responses by coupling to the RLP23 receptor complex显示文摘Plant cells recognize microbial patterns with the plasma-membrane-localized pattern-recognition receptors consisting mainly of receptor kinases(RKs) and receptor-like proteins(RLPs). RKs, such as bacterial flagellin receptor FLS2, and their downstream signaling components have been studied extensively. However, newly discovered regulatory components of RLP-mediated immune signaling, such as the nlp20 receptor RLP23, await identification. Unlike RKs, RLPs lack a cytoplasmic kinase domain, instead recruiting the receptor-like kinases(RLKs) BAK1 and SOBIR1. SOBIR1 specifically works as an adapter for RLP-mediated immunity. To identify new regulators of RLP-mediated signaling, we looked for SOBIR1-binding proteins(SBPs) in Arabidopsis thaliana using protein immunoprecipitation and mass spectrometry,identifying two G-type lectin RLKs, SBP1 and SBP2, that physically interacted with SOBIR1.SBP1 and SBP2 showed high sequence similarity,were tandemly repeated on chromosome 4, and also interacted with both RLP23 and BAK1. sbp1 sbp2 double mutants obtained via CRISPR-Cas9 gene editing showed severely impaired nlp20-induced reactive oxygen species burst, mitogenactivated protein kinase(MAPK) activation, and defense gene expression, but normal flg22-induced immune responses. We showed that SBP1 regulated nlp20-induced immunity in a kinase activityindependent manner. Furthermore, the nlp20-induced the RLP23–BAK1 interaction, although not the flg22-induced FLS2–BAK1 interaction, was significantly reduced in sbp1 sbp2. This study identified SBPs as new regulatory components in RLP23 receptor complex that may specifically modulate RLP23-mediated immunity by positively regulating the interaction between the RLP23 receptor and the BAK1 co-receptor. | Yazhou Bao Yixin Li Qin Chang Rubin Chen Weijie Wang Qian Zhang Shuxian Chen Guangyuan Xu Xiaodan Wang Fuhao Cui Daolong Dou Xiangxiu Liang | 2023 | Journal of Integrative Plant Biology2023，65，5： | 0 |
| 18 | Ti4+-incorporated fluorite-structured high-entropy oxide (Ce,Hf,Y,Pr,Gd)O_(2−δ): Optimizing preparation and CMAS corrosion behavior显示文摘Environmental barrier coatings(EBCs)with excellent chemical resistance and good high-temperature stability are of great significance for their applications in next-generation turbine engines.In this work,a new type of high-entropy fluorite-structured oxide(Ce_(0.2)Hf_(0.2)Y_(0.2)Pr_(0.2)Gd_(0.2))O_(2−δ)(HEFO-1)with different Ti^(4+)contents were successfully synthesized.Minor addition of Ti4+could be dissolved into a high-entropy lattice to maintain the structure stable,effectively reducing the phase formation temperature and promoting the shrinkage of bulk samples.Heat treatment experiments showed that all the samples remained a single phase after annealing at 1200–1600℃for 6 h.In addition,high-entropy(Ce_(0.2)Hf_(0.2)Y_(0.2)Pr_(0.2)Gd_(0.2)Ti_(0.2x)O_(2−δ)demonstrated great resistance to calcium–magnesium–alumina–silicate(CMAS)thermochemical corrosion.When the content of Ti was increased to x=0.5,the average thickness of the reaction layer was about 10.5µm after being corroded at 1300℃for 10 h.This study reveals that high-entropy(Ce_(0.2)Hf_(0.2)Y_(0.2)Pr_(0.2)Gd_(0.2)Ti_(0.2x)O_(2−δ)is expected to be a candidate for the next-generation EBC materials with graceful resistance to CMAS corrosion. | Fuhao CHENG Fengnian ZHANG Yufeng LIU Meng GUO Chufei CHENG Jiadong HOU Yang MIAO Feng GAO Xiaomin WANG | 2022 | Journal of Advanced Ceramics2022，11，11： | 0 |
您所在的机构暂未开通此部分的功能，请联系管理员