检索结果-南通市图书馆

Progress in Natural Science:Materials International 2006年第2期16卷 192-200页

作者： ZHOU Ling and chen Bin (Key Laboratory of Orogenic Belts and Crustal Evolution, MOE, school of earth and Space {3., Peking university, beijing 100871, china) Key Laboratory of Orogenic Belts and Crustal Evolution MOE School of Earth and Space Sciences Peking University Beijing 100871 China

The Hongshan syenitic pluton (South Taihang) is mainly made up of hornblende syenite and minor granite. SHRIMP zircon dating yields a U-Pb age of 13.±2.7 Ma for the emplacement of the pluton, while biotite Rb-Sr isotopic data give an isochron of 120. 3.2.4 Ma. Hongshan syenites show low silica, high alkalis and LILE such as Sr, and exhibit negligible Eu anomalies or slightly positive anomalies in the REE patterns. The syenites show quite enriched isotopic compositions with Isr from 0.7052 to 0. 7102 and εNd(t) from -7.5 to - 11.1. Petrogenesis of the pluton can be that partial melting of an enriched lithospheric mantle gave birth to an alkali basaltic magma, which subsequently underplated in the lower crust and experienced a coupled fractionation of ferromagnesian phases like pyroxene and hornblende and minor (china Plateau" in the Mesozoic.

关键词： syenite zircon SHRIMP Nd-Sr isotopes Taihang North china craton.

Nature of the Precambrian metamorphic blocks in the eastern segment of Central Tianshan:Constraint from geochronology and Nd isotopic geochemistry

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Science china earth sciences 2004年第12期47卷 1085-1094页

作者： liu Shuwen,guo Zhaojie,ZHANG Zhicheng,LI Qiugen & ZHENG Haifei The Key Laboratory of Orogenic Belts and Crustal Evolution,Ministry of Education,{3. school of earth and Space sciences,Peking university,beijing 100871,{3. The Key Laboratory of Orogenic Belts and Crustal Evolution Ministry of Education China school of earth and Space sciences Peking University Beijing China

Granitoid gneisses are widespread in Precambrian metamorphic blocks of eastern segment of the Central Tianshan Tectonic Zone, and they have intrusive contact relationships with their metamorphic sedimentary country rocks of Proterozoic Xingxingxia and Kawabulag groups. Zircon U-Pb ages from a granodioritic gneiss (IW11-1) and a parametamorphic schist (W05-9) are determined at the Weiya area. Euhedral prismatic zircons from the granodioritic gneiss (IW11-1) provide U-Pb isotopic discordia intercept ages of 1218±17 Ma and 426±26 Ma, respectively, and euhedral prismatic zircons from the parametamorphic schist (W05-9) display U-Pb isotopic discordia intercept ages of 1216±74 Ma and 290±15 Ma, respectively. A whole-rock Sm-Nd isotopic isochron is determined in augen granitoid gneiss samples at the Gang- gou-Kumishi area and we obtain the isochron age of 1142±120 Ma, and its ε Nd (t) = -4.3. These geochronological data suggest that these Precambrian metamorphic basement blocks within eastern segment of the Central Tianshan Tectonic Zone can be produced during 1140—1220 Ma, and occur a nearly homochronous metamorphism. Integrated to these geochronological data, Nd depleted mantle model ages (T DM ) and epsilon Nd(t) values of these granitoid gneiss samples indicate that they can derive from mixing in various scales both magmas from mantle and crust sources at a late Mesoproterozoic active continental margin tectonic environment. Similarity in geochronology, Sm-Nd isotopic geochemistry between Weiya-Xingxingxia, Pargangtag and Ganggou-Kumishi areas suggests that they could be a bigger uniform metamorphic basement block, which could be formed by the assembly of the supercontinent Rodinia and be separated by late geological processes.

关键词： Central Tianshan Tectonic Zone, Precambrian metamorphic blocks, granitoid gneisses, isotopic chronolo-gy, active continental margin, supercontinent Rodinia.

Track Fading and Its Applications in Archaeology, Tectonics and Geothermal Chronology in china

在线全文

学校读者我要写书评

暂无评论

Journal of earth Science 2013年第4期24卷 645-651页

作者：郭士伦袁万明陈宝流黄慰文刘顺生 Department of Nuclear Physics China Institute of Atomic Energy school of earth sciences and Resourses China University of Geosciences Department of Radioisotopes China Institute of Atomic Energy Institute of Vertebrate Paleontology and Paleoanthropology Chinese Academy of Sciences Guangzhou Institute of Geochemistry Chinese Academy of Sciences

Track fading is a basic phenomenon in track science and has been the source of informa- tion in geosciences. This article summarizes the knowledge of track fading and gives some examples of successful applications of track fading in archaeology, tectonics and geothermal chronology in china. The applications of track fading are classified into 5 modes：（1） mode of complete fading （annealing）; （2） mode of partial fading; （3. use of the dependence of track fading on time and temperature; （4） use of the differences of track fading between coexisting minerals; and （5） use of fading-reduced track length. Track fading mechanisms hints that scientists in geothermal chronology should adopt microprobes for quantitative elemental analysis to determine the detailed chemical compositions of each mineral grain or at least of the grains from each position of geological structures in order that one becomes well aware of the relation between the track fading behavior and chemical compositions of the mineral used.

关键词： track fading archaeology tectonics geothermal chronology.

Zircon SHRIMP U-Pb Dating and Neoproterozoic Metamorphism of Kangding and Yuanmou Intrusive Complexes,Sichuan and Yunnan

在线全文

学校读者我要写书评

暂无评论

Journal of earth Science 2009年第6期20卷 897-908页

作者：李大鹏陈岳龙罗照华赵俊香 school of the earth sciences and Resources China University of Geosciences Institute of Crustal Dynamics China Earthquake Administration

To clarify the relationship of the metamorphic intrusions along the west margin of the Yangtze craton and their metamorphic history after crystallization, the petrochemical and trace element geochemical characters, zircon SHRIMP U-Pb dating, and the chemical compositions of coexisting hornblendes and plagioclases from Neoproterozoic metamorphic intrusions in Kangding （康定）, Sichuan （四川） Province, and Yuanmou （元谋）, Yunnan （云南） Province, were studied. Combined with the former published data, it is indicated that the Kangding granitic plutons and Yuanmou complex in the west margin of the Yangtze craton generally formed at the same period. Metamorphic event at ~700 Ma existed extensively, at least covering from Kangding area in Sichuan to the Eshan （峨山） area in Central Yunnan. Moreover, amphibolite facies may represent the peak regional metamorphic condition.

关键词： Yangtze craton Kangding-Yuanmou complex SHRIMP metamorphic history.

Unveiling factuality and injecting knowledge for LLMs via reinforcement learning and data proportion

在线全文

学校读者我要写书评

暂无评论

Science china(Information sciences) 2024年第10期67卷 389-390页

作者： Wenjun KE Ziyu SHANG Zhizhao LUO Peng WANG Yikai guo Qi liu Yuxuan chen school of Computer Science and Engineering Southeast University Key Laboratory of New Generation Artificial Intelligence Technology and Its Interdisciplinary Applications(Southeast university) beijing Institute of Technology Zhuhai beijing Institute of Computer Technology and Application

Large language models(LLMs) have demonstrated remarkable effectiveness across various natural language processing(NLP) tasks, as evidenced by recent studies [1, 2]. However, these models often produce responses that conflict with reality due to the unreliable distribution of facts within their training data, which is particularly critical for applications requiring high credibility and accuracy [3..

关键词：

同方期刊数据库

Natural evidence of coronaviral 2′-O-methyltransferase activity affecting viral pathogenesis via improved substrate RNA binding

在线全文

学校读者我要写书评

暂无评论

Signal Transduction and Targeted Therapy 2024年第6期9卷 2819-2834页

作者： Jikai Deng Shimin Yang Yingjian Li Xue Tan Jiejie liu Yanying Yu Qiang Ding chengpeng Fan Hongyun Wang Xianyin chen Qianyun liu Xiao guo Feiyu Gong Li Zhou Yu chen State Key Laboratory of Virology RNA InstituteCollege of Life Sciences and Frontier Science Center for Immunology and MetabolismWuhan UniversityWuhanChina school of Medicine Tsinghua UniversityBeijingChina school of Basic Medical sciences Wuhan UniversityWuhanChina Animal Bio-Safety Level Ⅲ Laboratory/Institute for Vaccine Research Wuhan University School of MedicineWuhanChina

Previous studies through targeted mutagenesis of K-D-K-E motif have demonstrated that 2′-O-MTase activity is essential for efficient viral replication and immune ***,the K-D-K-E catalytic motif of 2′-O-MTase is highly conserved across numerous viruses,including flaviviruses,vaccinia viruses,coronaviruses,and extends even to ***,we observed a stronger 2′-O-MTase activity in SARS-CoV-2 compared to SARS-CoV,despite the presence of a consistently active catalytic *** further identified critical residues(Leu-3.,Asn-13. and Ile-153.which served as determinants of discrepancy in 2′-O-MTase activity between SARS-CoV-2 and *** residues significantly enhanced the RNA binding affinity of 2′-O-MTase and boosted its versatility toward RNA *** interest,a triple substitution(Leu^(3.)→Ile^(3.),Asn^(13.)→His^(13.),Ile^(153.→Leu^(153.,from SARS-CoV-2 to SARS-CoV)within nsp16 resulted in a proportional reduction in viral 2′-O-methylation and impaired viral ***,it led to a significant upregulation of type I interferon(IFN-I)and proinflammatory cytokines both in vitro and vivo,relying on the cooperative sensing of melanoma differentiation-associated protein 5(MDA5)and laboratory of genetics and physiology 2(LGP2).In conclusion,our findings demonstrated that alterations in residues other than K-D-K-E of 2′-O-MTase may affect viral replication and subsequently influence *** changes in nsp16 residues is crucial as it may aid in identifying and assessing future alteration in viral pathogenicity resulting from natural mutations occurring in nsp16.

关键词： pathogenesis impaired alterations

Precise determination of the pole position of the exotic Z_(c)(3.00)

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Science china(Physics,Mechanics & Astronomy) 2024年第9期67卷 84-90页

作者： Yun-Hua chen Meng-Lin Du Feng-Kun guo school of Mathematics and Physics University of Science and Technology BeijingBeijing 100083China school of Physics University of Electronic Science and Technology of ChinaChengdu 611731China CAS Key Laboratory of Theoretical Physics Institute of Theoretical PhysicsChinese Academy of SciencesBeijing 100190China school of Physical sciences University of Chinese Academy of SciencesBeijing 100049China Peng Huanwu Collaborative Center for Research and Education Beihang UniversityBeijing 100191China

We perform a unified description of the experimental data of the π^(+)π^(-)and J/ψπ^(±)invariant mass spectra for e^(+)e^(-)→J/ψπ^(+)π^(-)and the D^(0)D^(*-)mass spectrum for e^(+)e^(-)→D^(0)D^(*-)π^(+)at e^(+)e^(-)center-of-mass energies 4.23.and 4.26 *** analysis takes into account open-charm meson loops that contain triangle singularities,the J/ψπ-DD^(*)coupled-channel interaction respecting unitarity,and the strong ππ-KK final state interaction using dispersion *** analysis leads to a precise determination of the Z_(c)(3.00)pole with the pole mass and width(3.80.7±1.7_(stat)±22.4_(syst))MeV and(3..9±1.4_(stat)±15.3.(syst))MeV,respectively,and hints at that the DD^(*)molecular and non-molecular components are of similar importance in the Z_(c)(3.00)formation.

关键词： exotic hadrons dispersion relations final state interaction triangle singularity

Cosmological interpretation for the stochastic signal in pulsar timing arrays

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Science china(Physics,Mechanics & Astronomy) 2024年第4期67卷 43-50页

作者： Yu-Mei Wu Zu-cheng chen Qing-guo Huang school of Fundamental Physics and Mathematical sciences Hangzhou Institute for Advanced StudyUniversity of Chinese Academy of SciencesHangzhou 310024China school of Physical sciences University of Chinese Academy of SciencesBeijing 100049China Department of Astronomy Beijing Normal UniversityBeijing 100875China Advanced Institute of Natural sciences Beijing Normal UniversityZhuhai 519087China Department of Physics and Synergistic Innovation Center for Quantum Effects and Applications Hunan Normal UniversityChangsha 410081China CAS Key Laboratory of Theoretical Physics Institute of Theoretical PhysicsChinese Academy of SciencesBeijing 100190China

The pulsar timing array(PTA)collaborations have recently reported compelling evidence for a stochastic signal consistent with a gravitational-wave *** this paper,we combine the latest data sets from NANOGrav,PPTA,and EPTA to explore cosmological interpretations for the PTA signal from first-order phase transitions,domain walls,and cosmic strings,*** find that the domain wall model is strongly disfavored with the Bayes factors compared with the first-order phase transitions and cosmic strings being 1/90 and 1/189,respectively,breaking the degeneracy among these models in individual data *** also find that:(1)a strong phase transition at temperatures below the electroweak scale is favored,and the bubble collisions make the dominant contribution to the energy density spectrum;(2)a small reconnection probability p<1.55×10^(-1)allowed by strings in(super)string theory is favored at the 95%confidence level,and ground-based detectors can further constrain the parameter space.

关键词： puslar timing arrays gravitational-wave background first-order phase transitions domain walls cosmic strings

Evaluation and attribution of trends in compound dry-hot events for major river basins in china

在线全文

学校读者我要写书评

暂无评论

Science china earth sciences 2024年第1期67卷 79-91页

作者： Shaotang XIONG Tongtiegang ZHAO chengchao guo Yu TIAN Fang YANG Wenlong chen Xiaohong chen Key Laboratory of Water Security Guarantee in Guangdong-Hong Kong-Marco Greater Bay Area of Ministry of Water Resources&Sun Yatsen university/Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai) Guangzhou 510275China china Institute of Water Resource and Hydropower Research Beijing 100038China Pearl River Hydraulic Research Institute Guangzhou 510611China

Concurrent compound dry and hot events(CDHEs)amplified more damange on the ecosystems and human society than individual *** climate change,compound dry and hot events become more frequent on a global *** paper proposes a mathematical method to quantitatively attribute changes of CDHEs to changes of precipitation,change in temperature and change in the dependence between precipitation and *** attribution is achieved by formulating the total differential equation of the return period of CDHEs among Meta-gaussian model.A case study of china is devised based on monthly precipitation and temperature data during the period from 1921 to 2020 for 80 major river *** is found that temperature is the main driving factor of increases in CDHEs for 49 major river basins in china,except for the upper and middle reaches of the Yangtze *** West china,precipitation changes drove the increase in CDHEs in 18 river basins(23.),particularly in parts of North Xinjiang,Qinghai and *** the other hand,dependence between precipitation and temperature dominated changes of CDHEs in 13.river basins(16%)of china with other factors,including parts of South china,East china and Northwestern ***,changes in both the mean and spread of precipitation and temperature can also contribute to changes in CDHEs.

关键词： Climate extreme Compound dry and hot extreme Precipitation Temperature Return period

Sugarcane leaves-derived polyphenols alleviate metabolic syndrome and modulate gut microbiota of ob/ob mice

在线全文

学校读者我要写书评

暂无评论

Food Science and Human Wellness 2024年第2期13卷 633-648页

作者： Li Sun Tao Wang Baosong chen Cui guo Shanshan Qiao Jinghan Lin Huan Liao Huanqin Dai Bin Wang Jingzu Sun Hongwei liu State Key Laboratory of Mycology Institute of MicrobiologyChinese Academy of SciencesBeijing 100101China Savaid Medicine school University of Chinese Academy of SciencesBeijing 100101China Guangxi Academy of sciences Nanning 530007China

Sugarcane leaves-derived polyphenols(SLP)have been demonstrated to have diverse health-promoting benefits,but the mechanism of action has not been fully *** study aimed to investigate the anti-metabolic disease effects of SLP and the underlying mechanisms in *** the current study,we prepared the SLP mainly consisting of three flavonoid glycosides,three phenol derivatives,and two lignans including one new compound,and further demonstrated that SLP reduced body weight gain and fat accumulation,improved glucose and lipid metabolism disorders,ameliorated hepatic steatosis,and regulated short-chain fatty acids(SCFAs)production and secondary bile acids metabolism in ob/ob ***,SLP largely altered the gut microbiota composition,especially enriching the commensal bacteria Akkermansia muciniphila and Bacteroides *** gavage with the above two strains ameliorated metabolic syndrome(MetS),regulated secondary bile acid metabolism,and increased the production of SCFAs in high-fat diet(HFD)-induced obese *** results demonstrated that SLP could be used as a prebiotic to attenuate MetS via regulating gut microbiota composition and further activating the secondary bile acids-mediated gut-adipose axis.

关键词： Sugarcane leaves-derived polyphenols Metabolic syndrome Bacteroides acidifaciens Akkermansia muciniphila Secondary bile acids metabolism