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An Efficient Method for Identifying Lower Limb Behavior Intentions Based on Surface Electromyography 被引量:1
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作者 liuyi ling Yiwen Wang +5 位作者 Fan Ding li Jin Bin Feng Weixiao li Chengjun Wang xianhua li 《Computers, Materials & Continua》 SCIE EI 2023年第12期2771-2790,共20页
Surface electromyography(sEMG)is widely used for analyzing and controlling lower limb assisted exoskeleton robots.Behavior intention recognition based on sEMG is of great significance for achieving intelligent prosthe... Surface electromyography(sEMG)is widely used for analyzing and controlling lower limb assisted exoskeleton robots.Behavior intention recognition based on sEMG is of great significance for achieving intelligent prosthetic and exoskeleton control.Achieving highly efficient recognition while improving performance has always been a significant challenge.To address this,we propose an sEMG-based method called Enhanced Residual Gate Network(ERGN)for lower-limb behavioral intention recognition.The proposed network combines an attention mechanism and a hard threshold function,while combining the advantages of residual structure,which maps sEMG of multiple acquisition channels to the lower limb motion states.Firstly,continuous wavelet transform(CWT)is used to extract signals features from the collected sEMG data.Then,a hard threshold function serves as the gate function to enhance signals quality,with an attention mechanism incorporated to improve the ERGN’s performance further.Experimental results demonstrate that the proposed ERGN achieves extremely high accuracy and efficiency,with an average recognition accuracy of 98.41%and an average recognition time of only 20 ms-outperforming the state-of-the-art research significantly.Our research provides support for the application of lower limb assisted exoskeleton robots. 展开更多
关键词 SEMG movement intention efficient network convolutional neural network
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Multi-Branch High-Dimensional Guided Transformer-Based 3D Human Posture Estimation
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作者 xianhua li Haohao Yu +2 位作者 Shuoyu Tian Fengtao lin Usama Masood 《Computers, Materials & Continua》 SCIE EI 2024年第3期3551-3564,共14页
The human pose paradigm is estimated using a transformer-based multi-branch multidimensional directed the three-dimensional(3D)method that takes into account self-occlusion,badly posedness,and a lack of depth data in ... The human pose paradigm is estimated using a transformer-based multi-branch multidimensional directed the three-dimensional(3D)method that takes into account self-occlusion,badly posedness,and a lack of depth data in the per-frame 3D posture estimation from two-dimensional(2D)mapping to 3D mapping.Firstly,by examining the relationship between the movements of different bones in the human body,four virtual skeletons are proposed to enhance the cyclic constraints of limb joints.Then,multiple parameters describing the skeleton are fused and projected into a high-dimensional space.Utilizing a multi-branch network,motion features between bones and overall motion features are extracted to mitigate the drift error in the estimation results.Furthermore,the estimated relative depth is projected into 3D space,and the error is calculated against real 3D data,forming a loss function along with the relative depth error.This article adopts the average joint pixel error as the primary performance metric.Compared to the benchmark approach,the estimation findings indicate an increase in average precision of 1.8 mm within the Human3.6M sample. 展开更多
关键词 Key point detection 3D human posture estimation computer vision deep learning
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Efficacy of Carbamazepine Combined with Botulinum Toxin A in the Treatment of Blepharospasm and Hemifacial Spasm 被引量:2
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作者 xianhua li Shaochun lin +3 位作者 Yanfei Hu liya liu Jubo liu Yichun Hong 《Eye Science》 CAS 2012年第4期178-181,共4页
Purpose:To observe the efficacy of the combined treatment of carbamazepine and botulinum toxin A for blepharospasm and hemifacial spasm. Methods:Fifty-eight patients with either blepharospasm or hemifacial spasm were ... Purpose:To observe the efficacy of the combined treatment of carbamazepine and botulinum toxin A for blepharospasm and hemifacial spasm. Methods:Fifty-eight patients with either blepharospasm or hemifacial spasm were randomly divided into treatment and control groups. In the treatment group, 30 patients were administered with local intramuscular injections of botulinum toxin A and oral carbamazepine 100 mg/time,3 times/day for 60 days. Twenty-eight subjects in the control group under-went local intramuscular injections of botulinum toxin A only. Results:After combined treatment, the complete remission rate was 90%, which was significantly higher than that of the of the control group (67.9% , P<0.05,χ2 =4.733). However, no statistical significance was noted regarding the duration of therapeutic effects between the treatment group (range 14~40 weeks; 19.2 weeks on average) and control group (range 12~36 weeks; 18 weeks on average). Conclusion:The combined therapy of carbamazepine and topical injections of botulinum toxin A had increased efficacy in the treatment of blepharospasm or hemifacial spasm, but had no significant effect in terms of the duration of the therapeutic effect. 展开更多
关键词 A型肉毒毒素 综合治疗 卡马西平 肌痉挛 眼睑 和面 功效 肉毒杆菌毒素
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Low diastolic blood pressure and adverse outcomes in inpatients with acute exacerbation of chronic obstructive pulmonary disease: A multicenter cohort study
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作者 Chen Zhou Qun Yi +15 位作者 Yuanming Luo Hailong Wei Huiqing Ge Huiguo liu xianhua li Jianchu Zhang Pinhua Pan Mengqiu Yi lina Cheng liang liu Jiarui Zhang lige Peng Adila Aili Yu liu Jiaqi Pu Haixia Zhou 《Chinese Medical Journal》 SCIE CAS CSCD 2023年第8期941-950,共10页
Background:Although intensively studied in patients with cardiovascular diseases(CVDs),the prognostic value of diastolic blood pressure(DBP)has little been elucidated in patients with acute exacerbation of chronic obs... Background:Although intensively studied in patients with cardiovascular diseases(CVDs),the prognostic value of diastolic blood pressure(DBP)has little been elucidated in patients with acute exacerbation of chronic obstructive pulmonary disease(AECOPD).This study aimed to reveal the prognostic value of DBP in AECOPD patients.Methods:Inpatients with AECOPD were prospectively enrolled from 10 medical centers in China between September 2017 and July 2021.DBP was measured on admission.The primary outcome was all-cause in-hospital mortality;invasive mechanical ventilation and intensive care unit(ICU)admission were secondary outcomes.Least absolute shrinkage and selection operator(LASSO)and multivariable Cox regressions were used to identify independent prognostic factors and calculate the hazard ratio(HR)and 95%confidence interval(CI)for adverse outcomes.Results:Among 13,633 included patients with AECOPD,197(1.45%)died during their hospital stay.Multivariable Cox regression analysis showed that low DBP on admission(<70 mmHg)was associated with increased risk of in-hospital mortality(HR=2.16,95%CI:1.53–3.05,Z=4.37,P<0.01),invasive mechanical ventilation(HR=1.65,95%CI:1.32–2.05,Z=19.67,P<0.01),and ICU admission(HR=1.45,95%CI:1.24–1.69,Z=22.08,P<0.01)in the overall cohort.Similar findings were observed in subgroups with or without CVDs,except for invasive mechanical ventilation in the subgroup with CVDs.When DBP was further categorized in 5-mmHg increments from<50 mmHg to≥100 mmHg,and 75 to<80 mmHg was taken as reference,HRs for in-hospital mortality increased almost linearly with decreased DBP in the overall cohort and subgroups of patients with CVDs;higher DBP was not associated with the risk of in-hospital mortality.Conclusion:Low on-admission DBP,particularly<70 mmHg,was associated with an increased risk of adverse outcomes among inpatients with AECOPD,with or without CVDs,which may serve as a convenient predictor of poor prognosis in these patients.Clinical Trial Registration:Chinese Clinical Trail Registry,No.ChiCTR2100044625. 展开更多
关键词 Acute exacerbation of chronic obstructive pulmonary disease Diastolic blood pressure Prognostic factors INPATIENTS In-hospital mortality
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深时重大生物和气候事件与全球变化:进展与挑战 被引量:6
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作者 沈树忠 张飞飞 +11 位作者 王文倩 王向东 樊隽轩 陈吉涛 王博 曹剑 杨石岭 张华 李高军 邓涛 李献华 陈骏 《科学通报》 EI CAS CSCD 北大核心 2024年第2期268-285,共18页
地球自5.4亿年前现代生态系统形成至今,发生了多次与碳循环扰动有关的重大气候事件.这些事件的触发机制、发展过程、环境变化及其伴随的生物响应型式为科学评估当今全球变化背景下生物多样性现状提供重要借鉴.然而,古-今生态系统变化时... 地球自5.4亿年前现代生态系统形成至今,发生了多次与碳循环扰动有关的重大气候事件.这些事件的触发机制、发展过程、环境变化及其伴随的生物响应型式为科学评估当今全球变化背景下生物多样性现状提供重要借鉴.然而,古-今生态系统变化时间尺度大不相同,高分辨率关键环境因子(温度、CO_(2)、降雨量、海洋氧化还原条件等)在深时记录中亦难以获取,深时海陆生物多样性模式尚缺乏高分辨率记录.因此,当今全球变化与深时记录对比存在巨大鸿沟.地球5.4亿年以来大部分时间处于两极无冰的温室状态,期间伴随多次极冷和极热气候事件,但地球深时重大生物演化和气候事件的关系复杂.生物多样性在变冷的奥陶纪早期、晚古生代大冰期、晚新生代大冰期以及中-晚三叠世和白垩纪热室期均呈现稳定增加,而在奥陶纪末冰期快速降温期间和二叠纪末、三叠纪末、白垩纪末火山排气作用导致的快速升温过程中急剧下降.地质时期生物多样性对气候变化的不同响应型式表明,生物多样性变化的根本驱动因素可能不是简单的温度、大气CO_(2)浓度等环境因子的背景值高或低,而是环境因子的变化速率(环境变率).变率较小,环境相对稳定,生物有足够的时间适应环境变化,生物多样性不会丧失,甚至繁盛.反之,若环境因子变率过大,超出了生态系统的承受力,生物来不及适应,生物多样性就会显著降低,甚至引发大灭绝.已有模拟和计算表明,当今地球碳排放的速度有可能超过了地质历史时期任何一次生物大灭绝事件.因此,避免环境突变事件和生物大灭绝的再次发生成为政界、科学界和普通民众关注的焦点.打通地球多圈层界限,开展古-今地质记录、冷-热极端气候、海-陆生态系统和长-短时间尺度的综合对比研究,并通过建立适用于深时的地球系统模型,模拟重大生物和环境事件的背景与发生过程,是地球系统科学未来发展的重要方向. 展开更多
关键词 深时极端气候 重大生物事件 环境变率 全球变化 地球系统模拟
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Geological context of the Chang’e-6 landing area and implications for sample analysis
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作者 Zongyu Yue Sheng Gou +8 位作者 Shujuan Sun Wei Yang Yi Chen Yexin Wang Honglei lin Kaichang Di Yangting lin xianhua li Fuyuan Wu 《The Innovation》 EI 2024年第5期64-71,63,共9页
Research on returned samples can provide ground truth for the study of the geological evolution history of the Moon.However,previous missions all collected samples from the near side of the Moon,which is significantly... Research on returned samples can provide ground truth for the study of the geological evolution history of the Moon.However,previous missions all collected samples from the near side of the Moon,which is significantly different from the far side of the Moon in terms of the thickness of the lunar crust,magma activity,and composition.Therefore,the samples from the far side of the Moon are of great significance for a comprehensive understanding of the history of the Moon.China’s Chang’e-6(CE-6)probe has successfully landed on the lunar far side and will return samples in the coming days.With the precise location of the CE-6 landing site,a detailed analysis of the geological background is conducted in this research.The landing site of CE-6 is within the Apollo crater,which is inside the largest impact basin on the Moon,i.e.,the South Pole-Aitken(SPA)basin.According to the numerical simulation of the formation process of the SPA basin,CE-6 landed at the edge of the SPA impact melting zone,which is presumably composed of impact melt of the lunar mantle.The Apollo crater subsequently excavated deep material again,which constitutes the basement of the CE-6 landing area.Later,erupted basalt covered these basement rocks,and they also constitute the main source of the CE-6 samples.Based on the dating method of crater size-frequency distribution,we find that the basalt is2.50 Ga.The CE-6 samples also possibly contain basement rocks as excavated and ejected by craters,and they can provide crucial information for our understanding of lunar geological history along with the basalt samples. 展开更多
关键词 basalt basement constitute
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Homogeneous Management and Application of Appropriate Technology for TCM Care in County Medical Communities
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作者 liyuan Chen Zhenhua Luo +2 位作者 xianhua li Ya Chen Mengyu Chang 《Journal of Intelligent Medicine and Healthcare》 2022年第2期69-77,共9页
Objective:Explore the homogeneous management of appropri-ate technology for Traditional Chinese Medicine(TCM)care based on the county medical community platform.Methods:The hospital has formed a county medical communi... Objective:Explore the homogeneous management of appropri-ate technology for Traditional Chinese Medicine(TCM)care based on the county medical community platform.Methods:The hospital has formed a county medical community since 2020,based on which the platform develops homogeneous management of appropriate technologies for TCM nursing,establishes a medical training center,a remote consultation center and a TCM nursing quality control center,strengthens the construction of TCM nursing specialties,integrates TCM with public health and consolidates information support.The“321”model was developed,with January 2021 to December 2021 as the post-implementation period and January 2020 to December 2020 as the pre-implementation period,to compare the application of TCM nursing techniques before and after the implementation.Results:After the implementation of homogeneous management of TCM nursing techniques in the medical community units,the TCM nursing competence of primary care staff,patient compliance and satisfaction were significantly improved.Conclusion:The implementation of homogeneous management of TCM nursing techniques in the medical community units can enhance the TCM service capacity of primary care staff and improve the“sense of access to care”of patients. 展开更多
关键词 Medical community homogeneous nursing
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Return to the Moon:New perspectives on lunar exploration
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作者 Yangting lin Wei Yang +24 位作者 Hui Zhang Hejiu Hui Sen Hu Long Xiao Jianzhong liu Zhiyong Xiao Zongyu Yue Jinhai Zhang Yang liu Jing Yang Honglei lin Aicheng Zhang Dijun Guo Sheng Gou lin Xu Yuyang He Xianguo Zhang liping Qin Zongcheng ling Xiongyao li Aimin Du Huaiyu He Peng Zhang Jinbin Cao xianhua li 《Science Bulletin》 SCIE EI CAS CSCD 2024年第13期2136-2148,共13页
Lunar exploration is deemed crucial for uncovering the origins of the Earth-Moon system and is the first step for advancing humanity’s exploration of deep space.Over the past decade,the Chinese Lunar Exploration Prog... Lunar exploration is deemed crucial for uncovering the origins of the Earth-Moon system and is the first step for advancing humanity’s exploration of deep space.Over the past decade,the Chinese Lunar Exploration Program(CLEP),also known as the Chang’e(CE)Project,has achieved remarkable milestones.It has successfully developed and demonstrated the engineering capability required to reach and return from the lunar surface.Notably,the CE Project has made historic firsts with the landing and on-site exploration of the far side of the Moon,along with the collection of the youngest volcanic samples from the Procellarum KREEP Terrane.These achievements have significantly enhanced our understanding of lunar evolution.Building on this success,China has proposed an ambitious crewed lunar exploration strategy,aiming to return to the Moon for scientific exploration and utilization.This plan encompasses two primary phases:the first crewed lunar landing and exploration,followed by a thousand-kilometer scale scientific expedition to construct a geological cross-section across the lunar surface.Recognizing the limitations of current lunar exploration efforts and China’s engineering and technical capabilities,this paper explores the benefits of crewed lunar exploration while leveraging synergies with robotic exploration.The study refines fundamental lunar scientific questions that could lead to significant breakthroughs,considering the respective engineering and technological requirements.This research lays a crucial foundation for defining the objectives of future lunar exploration,emphasizing the importance of crewed missions and offering insights into potential advancements in lunar science. 展开更多
关键词 Crewed lunar exploration Water and volatiles Composition and structure of lunar interior Volcanic activity and evolution of lunar MANTLE Space weathering and radiation environments Exploration technology
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Age of granulite from Huangtuling, Dabie Mountain:Pb-Pb dating of garnet by a stepwise dissolution technique 被引量:15
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作者 Hanwen Zhou xianhua li +3 位作者 Ying liu Zhendong You Shutian Suo Zengqiu Zhong 《Chinese Science Bulletin》 SCIE EI CAS 1999年第10期941-944,共4页
A new stepwise dissolution scheme, involving acids with different properties, enables the selective recovery of radiogenic and common Pb from a mineral, and makes single-mineral Pb-Pb dating possible. Garnet from a gr... A new stepwise dissolution scheme, involving acids with different properties, enables the selective recovery of radiogenic and common Pb from a mineral, and makes single-mineral Pb-Pb dating possible. Garnet from a granulite sample from Huangtuling, northern Dabie Mountain yields a Pb-Pb isochron age of (1098 ± 35) Ma, which is interpreted as the timing of peak metamorphism of granulite facies. 展开更多
关键词 GARNET STEPWISE dissolution technique PB-PB isochron age DATING of metamorphic rocks GRANULITE DABIE Mountain.
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Long-Term Reproducibility of SIMS Zircon U-Pb Geochronology 被引量:3
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作者 Wenhao Zhao Qiuli li +4 位作者 Yu liu Guoqiang Tang Xiaoxiao ling Jiao li xianhua li 《Journal of Earth Science》 SCIE CAS CSCD 2022年第1期17-24,共8页
Secondary ion mass spectrometry(SIMS) zircon U-Pb dating has been widely used to confine the absolute ages of the magmatic or metamorphic events and to distinguish multiple events.Here,a data set consisting of the zir... Secondary ion mass spectrometry(SIMS) zircon U-Pb dating has been widely used to confine the absolute ages of the magmatic or metamorphic events and to distinguish multiple events.Here,a data set consisting of the zircon standards dating data(~15 000 Ple?ovice and ~8 000 Qinghu items) accumulated for more than 8 years using the CAMECA IMS 1280 HR of the Institute of Geology and Geophysics,Chinese Academy of Sciences(IGGCAS) is compiled to evaluate the long-term external reproducibility.With Ple?ovice zircon as the calibration standard and Qinghu zircon as an unknown sample,the analytical uncertainties for single-spot(n = 7 723) and session analyses(n = 691,with more than 7 single spot analyses in one session) are 2.6% and 0.9%(2 RSD,relative standard deviation),respectively.It means that single-spot U-Pb dating for a standard-level zircon sample could vary 5.2% at 95% confidence level,while the average value(n > 7) for each session may vary 1.8%.Thus,these values should be considered as the minimum uncertainty when comparing single spot and individual session analysis results for multiple dating works on a certain geological event. 展开更多
关键词 ZIRCON U-Pb dating SIMS UNCERTAINTY REPRODUCIBILITY
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Effect of Al(OH)_(3) prepared from fly ash on the structural and catalytic properties of g-C_(3)N_(4)-based materials
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作者 Qingbo Yu xianhua li Qingping Wang 《Chinese Journal of Chemical Engineering》 SCIE EI CAS 2024年第10期44-51,共8页
In order to find the optimal combination method of secondary utilization of fly ash and graphite-phase carbon nitride(g-C_(3)N_(4))modification,an efficient composite photocatalyst of γ-Al_(2)O_(3)/g-C_(3)N_(4)was ob... In order to find the optimal combination method of secondary utilization of fly ash and graphite-phase carbon nitride(g-C_(3)N_(4))modification,an efficient composite photocatalyst of γ-Al_(2)O_(3)/g-C_(3)N_(4)was obtained by calcining the composite precursors of Al(OH)3/dicyandiamide(DCDA).The introduction of Al(OH)_(3)prepared by combining fly ash into the precursors causes hydrogen-bonding interactions between Al(OH)_(3)and DCDA,which facilitate the removal of N atoms from the edges of the CN framework of g-C_(3)N_(4)during condensation,and the composites prepared possess more cyano defects.In addition,γ-Al_(2)O_(3)and g-C_(3)N_(4)form a chemical bond at the interface,and this chemical bonding causes the density of the electron cloud in the vicinity of the N atoms to increase.Among them,the strongest chemical bonding between Al_(2)O_(3)and g-C_(3)N_(4)was observed in ACN-1,whereas the most cyanine defects were formed in ACN-1,which made ACN-1 exhibit the best photocatalytic degradation of methylene blue,which is 2.48 times higher than that of the pristine g-C_(3)N_(4). 展开更多
关键词 Precursors g-C_(3)N_(4) Waste treatment Catalyst Synthesis
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Insights into the origin of purely sediment-derived Himalayan leucogranites:Si-O isotopic constraints 被引量:8
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作者 Xiaochi liu xianhua li +5 位作者 Yu liu Lei Yang Qiuli li Fuyuan Wu Huimin Yu Fang Huang 《Science Bulletin》 SCIE EI CSCD 2018年第19期1243-1245,共3页
Granite is the dominant rock type in Earth’s continental crust.The origin of granite can be directly or indirectly related to the fractional crystallization of mantle-derived basaltic melt or the reworking of pre-exi... Granite is the dominant rock type in Earth’s continental crust.The origin of granite can be directly or indirectly related to the fractional crystallization of mantle-derived basaltic melt or the reworking of pre-existing continental or oceanic crust, which contribute to the growth of continental crust. Among the various types of granites, the peraluminous leucogranites in the Himalayan orogen, which are high in SiO_2(>73%) and low in mafic minerals (<5%), 展开更多
关键词 起源 同位素 沉积 岩石类型 花岗石 外壳 大陆 玄武岩
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Barium isotope evidence for the role of magmatic fluids in the origin of Himalayan leucogranites 被引量:9
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作者 Fang Huang Ruixia Bai +2 位作者 Gengxin Deng Xiaochi liu xianhua li 《Science Bulletin》 SCIE EI CSCD 2021年第22期2329-2336,M0004,共9页
As an important post-collisional magmatic product in the orogenic belt, the Himalayan leucogranites are the critical host rocks for a number of rare-metal mineralization(such as Li, Be, Cs, Rb, Nb, Ta, and Sn).However... As an important post-collisional magmatic product in the orogenic belt, the Himalayan leucogranites are the critical host rocks for a number of rare-metal mineralization(such as Li, Be, Cs, Rb, Nb, Ta, and Sn).However, there is still a lack of good understanding on the formation and evolution of the leucogranites.Particularly, the role of the magmatic fluids in transporting and enriching the rare elements is not clear.Here we measure Ba isotope compositions for leucogranites from the Kampa Dome of the Himalayan belt to understand the fluid activity and behavior of fluid-mobile elements during leucogranite formation. Our results show that the δ138/134 Ba of leucogranites range from -1.32‰ to +0.12‰, much lower than the literature values for S-type granites and various sedimentary materials, suggesting that the Ba isotope compositions of the leucogranites does not reflect the sedimentary source signatures. Instead, their low δ138/134 Ba is accompanied by non-charge-and-radius-controlled(CHARAC) twin-element(such as Nb/Ta) behaviors, clearly showing the involvement of magmatic fluids during magma evolution.Experimental studies suggest that the low δ138/134 Ba of the magmatic fluids most likely results from exsolution from a large deep magma reservoir. Such fluids not only modified Ba isotope compositions of the leucogranites, but also transported many fluid-mobile metal elements which may help form the rare metal ore deposits. Therefore, Ba isotope data provide new insights into formation and evolution of magmatic fluids and exploration of the rare-metal mineralization. 展开更多
关键词 HIMALAYA LEUCOGRANITE Barium isotopes Fluid interaction Rare-metal mineralization
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High resolution Porites Mg/Ca thermometer for the north of the South China Sea 被引量:2
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作者 Gangjian Wei xianhua li +2 位作者 Baofu Nie Min Sun Haichen liu 《Chinese Science Bulletin》 SCIE EI CAS 1999年第3期273-276,共4页
High resolution Mg/Ca ratios in the skeleton of a Porites lutea from the coastal area in the North of the South China Sea were precisely analyzed by ICP-MS. Compared with the instrument measured SST records, the Mg/Ca... High resolution Mg/Ca ratios in the skeleton of a Porites lutea from the coastal area in the North of the South China Sea were precisely analyzed by ICP-MS. Compared with the instrument measured SST records, the Mg/Ca ratios strongly correlate with the SSTs, even in time of 1982/83 EI N(?)io. Therefore, a coral Mg/Ca thermometer for the North of the South China Sea was established.Based on ICP-MS technique it can report sea surface temperatures to an accuracy of±0.5℃. 展开更多
关键词 PORITES lutea MG/CA THERMOMETER NORTH of the SOUTH China Sea.
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Zircon Xenocrysts from the Shaka Ridge Record Ancient Continental Crust:New U-Pb Geochronological and Oxygen Isotopic Data 被引量:1
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作者 Sergey G.Skublov Natalia A.Rumyantseva +3 位作者 Qiuli li Boris G.Vanshtein Dmitriy I.Rezvukhin xianhua li 《Journal of Earth Science》 SCIE CAS CSCD 2022年第1期5-16,共12页
Over the past two decades, a significant number of discoveries of ancient zircon xenocrysts in ocean-floor magmatic rocks have been reported. These findings provide compelling evidence for the presence of ancient cont... Over the past two decades, a significant number of discoveries of ancient zircon xenocrysts in ocean-floor magmatic rocks have been reported. These findings provide compelling evidence for the presence of ancient continental crust within young oceanic lithosphere. Almost all finds of ancient zircon xenocrysts within oceanic crust are from the Mid-Atlantic Ridge. For other localities, however, similar data are very limited. This report presents the first age determinations(U-Pb, SHRIMPII) and isotope-geochemical data(oxygen, trace and rare earth elements) for zircon xenocrysts from gabbro-diorites of the Shaka Ridge, in the vicinity of the Shaka fracture zone, near the western end of the Southwest Indian Ridge. The work is based on a study of bottom rock material dredged during expeditionary research on the R/V"Akademik Fedorov"(Russia) in 2016. The U-Pb isotope system of the zircon xenocrysts recorded a crystallization age of ~2.8 Ga at an upper discordia intercept and an age of ~600 Ma interpreted as the timing of a superimposed thermal event at a lower discordia intercept.The zircon xenocrysts show geochemical signatures of magmatic origin, i.e., fractionated REE distribution spectra with an increase in chondrite-normalized values from light to heavy REE, positive Ce anomalies and negative Eu anomalies, and high Th/U ratios(0.59-7.77). In discrimination diagrams based on a series of inter-element relationships, zircon compositions fall into the fields of zircons from rocks of continental crust, mostly granitoids. The Li content of the zircons is high(1.8 ppm-50 ppm),adding further evidence to their derivation from rocks of continental crust. During their residence within young oceanic crust, the zircon xenocrysts experienced alterations under the influence of submarine high-temperature hydrothermal fluids, which selectively affected the distribution of trace elements in the zircons and reduced the δ;O values to 1.75‰-3.15‰. The presence of obviously older zircons in Shaka gabbro-diorites clearly demonstrates the presence of ancient continental fragments and their recycling into the mantle at the western end of the Southwest Indian Ridge. 展开更多
关键词 ZIRCON U-Pb geochronology oxygen isotopes trace elements rare earth elements Shaka Ridge South Atlantic Southwest Indian Ridge
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Dynamic simulation of the tractor HMCVT under typical working conditions based on AMESim 被引量:1
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作者 Maohua Xiao Yuanfang Zhao +3 位作者 xianhua li Ghulam Hussain Shengjie Wang Yejun Zhu 《International Journal of Agricultural and Biological Engineering》 SCIE CAS 2022年第2期102-110,共9页
In order to study the dynamic characteristics of hydro-mechanical continuously variable transmission(HMCVT)under ploughing and sowing conditions,a complete simulation model of HMCVT is established based on AMESim soft... In order to study the dynamic characteristics of hydro-mechanical continuously variable transmission(HMCVT)under ploughing and sowing conditions,a complete simulation model of HMCVT is established based on AMESim software,including mechanical transmission model,pump controlled hydraulic motor speed control model and section changing hydraulic system model.In addition,the dynamic model of tractor is established.In order to verify the correctness of the simulation model,a test-bed is established.The test of tractor running speed and the test of pump controlled hydraulic motor system were carried out on the test-bed.The test results show that the simulation model of pump control hydraulic system can correctly reflect the change of transmission ratio of pump controlled hydraulic motor,and the simulation model can reflect the actual working condition change of clutch.Thus,the correctness of the previous simulation model based on AMESim is verified.Based on the simulation model established by AMESim,the dynamic characteristics of HMCVT under ploughing and sowing conditions are studied.The results show that:Under ploughing condition,the planetary platoon will have strong impact at the moment of throttle opening and changing section.Under sowing condition,the HMCVT will have a great impact at the time of variable cross section,but the variation range of rodent force decreases and the changing trend tends to be stable. 展开更多
关键词 TRACTOR HMCVT AMESIM dynamics simulation TEST
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Discovery of the highly depleted N-MORB-type volcanic rocks: new evidence for the Mianlue paleo-ocean 被引量:7
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作者 Jifeng Xu Xueyuan Yu +3 位作者 xianhua li Yinwen Han Jihu Shen Benren Zhang 《Chinese Science Bulletin》 SCIE EI CAS 1998年第6期510-514,共5页
The highly depleted N-MORB-type volcanic rocks have been discovered in Mianlue mélange of Qinling orogenic belt, central China. These mafic rocks are associated with the meta-peridotites, showing LREE-depleted pa... The highly depleted N-MORB-type volcanic rocks have been discovered in Mianlue mélange of Qinling orogenic belt, central China. These mafic rocks are associated with the meta-peridotites, showing LREE-depleted pattern, similar to N-MORB and typical ophiolites. It is indicated that an ancient ocean existed in the Mianlue area of Qinling orogenic belt during the late Paleozoic. 展开更多
关键词 N-MORB-type ROCKS OPHIOLITE QINLING Mianlue belt.
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