期刊文献+
共找到777篇文章
< 1 2 39 >
每页显示 20 50 100
Group Size and Composition of Black-and-White Snub-nosed Monkey (Rhinopithecus bieti) Estimated by Faecesof Sleeping Sites at Baima Snow Mountain 被引量:8
1
作者 崔亮伟 钟泰 +1 位作者 肖林 肖文 《Zoological Research》 CAS CSCD 北大核心 2006年第4期337-343,共7页
This study was designed to introduce a new method of estimating group size and composition of black-andwhite snub-nosed monkeys (Rhinopithecus bieti ) on the basis of faecal amount at sleeping sites at Mt. Baima Nat... This study was designed to introduce a new method of estimating group size and composition of black-andwhite snub-nosed monkeys (Rhinopithecus bieti ) on the basis of faecal amount at sleeping sites at Mt. Baima Nature Reserve. The monkeys spend nights in the form of one-male, multi-female units (OMUs) and all-male units (AMU), and their faecal pellets can be classified into three categories: adult males (the largest), adult females (moderate) and immatures (the smallest) based on their size. Total pellets were counted under sleeping trees used for two nights at Nanren village (99°04′E, 28°34′N, northwest of Yunnan Province, China) in each of four seasons in 2000- 2001. Moreover, data on group composition were collected when the monkeys were passing through an open gully in November 2001. Since the number of adults in OMUs shows a positive significant correlation with the amount of pellets amount in each season, the mean number of feces produced per night per individual is the slope of the regression lines. Thus, group size and composition can be relatively reliably and accurately estimated by the faeces under trees compared with the previous methods of estimation, including the use of monkeys' activities and tracks such as broken branches on steep slopes, in deep gorges and under lower visibility. The use of pellets for population estimates displayed 9.4% deviation in regards to population size of adult females. Some causes of the bias were also discussed. The method might be applicable to other monkey groups of this species if their habitats and main foods are similar to those of the study group. 展开更多
关键词 FECES group composition group size Rhinopithecus bieti Sleeping site
下载PDF
New Discovery and Zircon Hf Isotopic Composition of the Early Yanshannian Monzogranite in the Yingyangguan Group of Eastern Guangxi, China 被引量:2
2
作者 LI Xiang TU Bing +3 位作者 WANG Lingzhan TIAN Yang XIE Guogang ZHANG Jianyu 《Acta Geologica Sinica(English Edition)》 CAS CSCD 2018年第4期1653-1655,共3页
Objective The Yingyangguan Group is widely exposed in the southwestern segment of boundary belt between Yangtze and Cathaysian blocks and is mainly composed of a suit of lower-grade metamorphic marine volcanoclastic-... Objective The Yingyangguan Group is widely exposed in the southwestern segment of boundary belt between Yangtze and Cathaysian blocks and is mainly composed of a suit of lower-grade metamorphic marine volcanoclastic- sedimentary rocks (Zhou Hanwen et al., 2002). Its forming age and petrogenesis are critical for better understanding the orogenic process and relationship of the Yangtze and Cathaysian blocks since the Neoproterozoic. However, few zircon U-Pb ages of samples from the Yingyangguan Group have been reported, which are much debated, such as the metamorphic spilite (819±11 Ma), keratophyre (415.1±2.1 Ma) and ignimbrite (821.3±3.9 Ma) (Tian Yang et al., 2015 and references in). In this study, we focus on the new discovered Early Yanshannian monzogranite and its mafic enclaves from the Yingyangguan Group, and conducted zircon U-Pb dating and in-situ Hf isotopic analyses to constrain their petrogenesis. 展开更多
关键词 Hf ICP MS Pb New Discovery and Zircon Hf Isotopic composition of the Early Yanshannian Monzogranite in the Yingyangguan group of Eastern Guangxi China
下载PDF
Evaluate All the Order of Every Element in the Higher Order of Group for Addition and Multiplication Composition
3
作者 Md. Abdul Mannan Nazmun Nahar +3 位作者 Halima Akter Momtaz Begum Md. Amanat Ullah Shabnam Mustari 《International Journal of Modern Nonlinear Theory and Application》 2022年第2期11-30,共20页
This paper aims at treating a study on the order of every element for addition and multiplication composition in the higher order of groups for different algebraic structures as groups;order of a group and order of el... This paper aims at treating a study on the order of every element for addition and multiplication composition in the higher order of groups for different algebraic structures as groups;order of a group and order of element of a group in real numbers. Here we discuss the higher order of groups in different types of order which will give us practical knowledge to see the applications of the addition and multiplication composition. If G is a finite group, n is a positive integer and a &isins;G, then the order of the products na. When G is a finite group, every element must have finite order. However, the converse is false: there are infinite groups where each element has finite order. For example, in the group of all roots of unity in C<sup>×</sup> each element has finite order. Finally, we find out the order of every element of a group in different types of higher order of group. 展开更多
关键词 Order of Element of a group Addition composition Multiplication composition Modulo
下载PDF
Characteristics Evaluation of Modern Bituminous Binders in Group Hydrocarbon Composition and Their Application in Construction
4
作者 Vasily Koshkarov Ilya Shunyaev Evgeny Koshkarov 《Materials Sciences and Applications》 2023年第8期407-415,共9页
The article is the result of theoretical and experimental studies aimed at determining the structural groups of modern bituminous materials in order to assess the raw materials, production technology, rational directi... The article is the result of theoretical and experimental studies aimed at determining the structural groups of modern bituminous materials in order to assess the raw materials, production technology, rational directions for their use in construction, the road industry and waterproofing. Commercial oil bitumen, raw tars and heavy oil residues (semi-finished products) of oil refineries aimed at meeting large-tonnage needs have been studied. The assessment was carried out according to the group hydrocarbon composition, by liquid chromatography using model compounds. Comparative analysis showed a general trend for all studied samples of petroleum bitumen: low content of asphaltenes (from 3.9 to 23.9 wt.%), low content of resins (from 11 to 19.07 wt%), insufficient for the formation of stable structuring layers, and a significant content of aromatic hydrocarbons, including heavy aromatic compounds (more than 20 wt.%). An assumption was made about the influence of the origin and the structure obtained during the processing of asphaltenes and resins on the transition from one type of bituminous structure to another based on the lyophility of high-molecular group components. A comparative structural characteristic of heavy oil residues from gasoline and oil production is considered in comparison with bitumens of various viscosities. Recommendations are given on the technology of processing petroleum feedstock and the use of heavy oils in order to obtain a given bitumen structure for the production of rational bitumen products for construction and waterproofing. 展开更多
关键词 Bitumen TAR CONSTRUCTION WATERPROofING Oil Refining group Hydrocarbon composition Viscosity ASPHALTENES
下载PDF
The Microarea Composition of Garnet and Biotite from the Ji'an Group in Tonghua District and Its Significance as an Indicator of Metamorphic P-T-t Path
5
作者 卢良兆 靳是琴 +1 位作者 胡大千 董永胜 《Chinese Journal Of Geochemistry》 EI CAS 1997年第4期304-307,共4页
The garnet (Grt) and biotite (Bt) from gneisses of the Ji’ an Group are characterized by diffusion zoning at the rim, but equilibrium composition of metamorphic peak is usually remained in extensive interior area. Ga... The garnet (Grt) and biotite (Bt) from gneisses of the Ji’ an Group are characterized by diffusion zoning at the rim, but equilibrium composition of metamorphic peak is usually remained in extensive interior area. Garnet with growth zoning is also found in the kyanite zone.In the light of microarea compositional variation of Grt and Bt, the temperatuIe and pressuIe at the progressive, peak and post peak metamorphic stages are determined by correctly using GrtBt thermometer and GASP barometer. On this basis, a counterclockwise P-T-t path can be constructed, which reflects the closing process of an ensialic rift belt in this region during the Early Proterozoic. 展开更多
关键词 石榴石 黑云母 P-T-T轨迹 温度 压力 变质作用
下载PDF
Effect of Graphene Surface Functional Groups on the Mechanical Property of PMMA Microcellular Composite Foams 被引量:4
6
作者 LI Meijuan SHEN Qiang 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2019年第3期717-722,共6页
The functional groups on graphene sheets surface affect their dispersion and interfacial adhesion in polymer matrix. We compared the mechanical property of polymethymethacrylate(PMMA) microcellular foams reinforced ... The functional groups on graphene sheets surface affect their dispersion and interfacial adhesion in polymer matrix. We compared the mechanical property of polymethymethacrylate(PMMA) microcellular foams reinforced with graphene oxide(GO) and reduced graphene oxide(RGO) to investigate this influence of functional groups. RGO sheets were fabricated by solvent thermal reduction in DMF medium. UV-Vis, FT-IR and XPS analyses indicate the difference of oxygen-containing groups on GO and RGO sheets surface. The observation of SEM illustrates that the addition of a smaller number of GO or RGO sheets causes a fine cellular structure of PMMA foams with a higher cell density(about 1011 cells/cm3) and smaller cell sizes(about 1-2 μm) owing to their remarkable heterogeneous nucleation effect. Compared to GO reinforced foams, the RGO/PMMA foams own lower cell density and bigger cell size in their microstructure, and their compressive strength is lower even when the reinforcement contents are the same and the foam bulk density is higher. These results indicate that the oxygen-containing groups on GO sheets’ surface are beneficial to adhere CO2 to realize a larger nucleation rate, and their strong interaction with PMMA matrix improves the mechanical property of PMMA foams. 展开更多
关键词 GRAPHENE surface functional groupS PMMA MICROCELLULAR COMPOSITE FOAMS mechanical property
下载PDF
Effects of natural forest conversion and plantation tree species composition on soil macrofauna communities in Northeast China mountains 被引量:2
7
作者 Shuangjiao Ma Qingcheng Wang +3 位作者 Yong Zhang Limei Yan Donghai Cui Liqing Xu 《Journal of Forestry Research》 SCIE CAS CSCD 2023年第5期1475-1489,共15页
As primary and secondary forests are being replaced by plantations across the globe,the soil macrofauna community structure is also affected,but little is known about the impact of mixed culture plantations compared w... As primary and secondary forests are being replaced by plantations across the globe,the soil macrofauna community structure is also affected,but little is known about the impact of mixed culture plantations compared with monocultures on the soil macrofauna.To determine the impact of forest conversion on soil macrofauna,we surveyed the soil macrofauna in two broad-leaved and three coniferous monoculture stands and four coniferous-broadleaved mixed stands,and in adjacent reserved secondary stands as a reference.Soil macro fauna community composition was significant affected by forest type,season and their interaction(P<0.05).The abundance,taxa richness and diversity of soil macro fauna changed to different degrees depending on the plantation type.Broadleaved monoculture stands and secondary stands had similar macrofauna abundance and taxa richness,but values were lower in coniferous stands than in secondary stands.The Shannon index for macrofauna in coniferous stands was also the lowest,but the Pielou index did not differ between forest types.The negative effects of the conifer monoculture on soil macro fauna were not present in the mixed stands with broad-leaved trees.Forest conversion impacted soil properties;soil moisture,NO_(3)^(-),and pH were significant drivers of soil macrofauna community structure.The impact of forest conversion on soil macrofauna was closely dependent on tree species composition and diversity.The macro fauna community structure in the broadleaved and the mixed stands were relatively similar to that in the natural forest,and thus recommended for forest conversion in the study area. 展开更多
关键词 Forest conversion Plantation forest Tree species composition Soil macrofauna DIVERSITY Functional group
下载PDF
Magma Chamber Process of Post-collisional Magmatism: Insight from Textural and Elemental Characteristics of Plagioclase from the Tatun Volcanic Group, Northern Taiwan Volcanic Zone 被引量:1
8
作者 ZHANG Xia GUO Kun +4 位作者 ZHANG Yu LAI Zhiqing JIANG Shulong JIANG Wenpeng LI Jingbo 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2022年第5期1587-1599,共13页
The Taiwan mountain belt, one of the youngest orogenies in the world, is caused by the collision of the Luzon arc with the Eurasian margin, which leads to post-collisional extension and magmatism in the Northern Taiwa... The Taiwan mountain belt, one of the youngest orogenies in the world, is caused by the collision of the Luzon arc with the Eurasian margin, which leads to post-collisional extension and magmatism in the Northern Taiwan Volcanic Zone(NTVZ). The magma chamber process in this region has not previously been elucidated in detail. In this paper, the textural and compositional features of plagioclase phenocrysts in basalt from the Tatun Volcanic Group(TTVG) were studied to restrict the dynamics of magma system. Results show that the magma melts in TTVG are mainly sourced from the underlying MORB-like mantle wedge but influenced by incorporation of subduction components, causing the elevated Sr/Y and Ba/Y ratios in magma melts. The subduction components are mainly transported in the form of sediment melt. The plagioclase phenocrysts in the TTVG volcanic rocks are generally coarsely core-sieved with a clear rim. The An contents in the rims of plagioclase are much lower than those of cores, and elevated FeO concentrations are detected in the plagioclase rims. We propose there exists a double-layer magma chamber in this region. The core of the plagioclase was crystalized in the deeper quiescent magma chamber(~21 km), which was subsequently partially dissolved during the ascent of magma melt under H_(2)O-undersaturated condition, forming the typical coarsely sieved texture and synneusis. When this crystal-rich melt migrates into the shallower chamber, water saturation is reached and more sodic plagioclase formed as the rim of phenocryst. Due to the considerably higher fO_(2) in the shallow chamber than in the deeper one, and the distribution of Fe between plagioclase and melt positively correlates with fO_(2), the FeO content in the plagioclase rim elevates in conjunction with increasing fO_(2). 展开更多
关键词 PLAGIOCLASE textural and compositional features dynamics of magma system Tatun Volcanic group
下载PDF
Bucket Group Effect of the Composite Multi-bucket Structure
9
作者 Shucheng Jin Yanhua Yang Yongtao Zhang 《Journal of Marine Science and Application》 2014年第1期62-66,共5页
As a novel type of foundation in beach and shallow sea, the bucket structure is especially suitable for complex conditions such as soft clay ground and the worse types of sea environments. In this paper, the bearing c... As a novel type of foundation in beach and shallow sea, the bucket structure is especially suitable for complex conditions such as soft clay ground and the worse types of sea environments. In this paper, the bearing capacity of a multi-bucket structure is studied by experiments with a single bucket and four-bucket foundation in a saturated sand layer. Based on the experimental data and numerical analysis results, the bearing capacity behavior and the bucket group effect are compared and analyzed. Furthermore, some influential factors, such as the soil type, the ratio of length to diameter L/D, the ratio of the bucket spacing to the bucket diameter S/D, and the bucket number are introduced and their effects on the multi-bucket structural capacity are investigated. The vertical static capacity adjustment factor is introduced to evaluate the bucket group effects of the multi-bucket foundation. 展开更多
关键词 BUCKET group EFFECT COMPOSITE multi-bucket structure bearing capacity displacement control method vertical staticcapacity adjustment factor
下载PDF
Sequence stratigraphy and lithofacies paleogeography of the Middle–Upper Cambrian Xixiangchi Group in the Sichuan Basin and its adjacent area, SW China
10
作者 LI Wei FAN Ru +4 位作者 JIA Peng LU Yuanzheng ZHANG Zhijie LI Xin DENG Shenghui 《Petroleum Exploration and Development》 2019年第2期238-252,共15页
Based on isotopic, lithologic and electrical data and logging cycle analysis technique, stratigraphic sequences in the Middle-Upper Cambrian Xixiangchi Group in the Sichuan Basin and its adjacent area are divided, and... Based on isotopic, lithologic and electrical data and logging cycle analysis technique, stratigraphic sequences in the Middle-Upper Cambrian Xixiangchi Group in the Sichuan Basin and its adjacent area are divided, and its sedimentary characteristics and evolution are analyzed. The Xixiangchi Group can be divided into 5 third-order sequences(Sql-Sq5), of which sequences Ⅰ to Ⅲ(Sql-Sq3) are relatively complete, sequences Ⅳ and Ⅴ are denuded in the Late Cambrian because of the Dian-Chuan paleo-uplifts.Third-order sequences of the Xixiangchi Group in this area have the characteristics of thin in the west and thick in the east, showing that the Caledonian paleo-uplift is a synsedimentary paleo-uplift and the paleogeomorphology in the platform is a gentle slope. Sequence Ⅰdevelops high stand systems tract and transgressive systems tract. The other third-order sequences are dominated by highstand systems tracts, and the transgressive systems tracts last shortly in time and are limited in area. The basic features of evaporative-restricted platform of gentle slope type developed continuously in the sedimentary period of the Xixiangchi Group, its sedimentary environment of "high in west and low in east" and the change of micro paleogeomorphology in the platform control the continuous development of sedimentary facies. Open platform is developed only in sequence Ⅰ and sequence Ⅱ, and the inner beach of the platform and the edge beach of the platform are mostly developed in sequence Ⅱ and sequence Ⅲ. It indicates that there are two platform margin zones in the study area,a relatively stable, large-scale platform marginal zone in NE Guizhou-Western Hunan and Hubei, and a moving and small-scale platform marginal zone in North Chongqing-Western Hubei. 展开更多
关键词 Sichuan Basin Middle–Upper CAMBRIAN Xixiangchi group SEQUENCE STRATIGRAPHY third-order SEQUENCE carbon isotope composition lithofacies PALEOGEOGRAPHY sedimentary environment evolution
下载PDF
Effects of Composted and Thermally Dried Sewage Sludges on Soil and Soil Humic Acid Properties 被引量:6
11
作者 J. M. FERNNDEZ N. SENESI +2 位作者 C. PLAZA G. BRUNETTI A. POLO 《Pedosphere》 SCIE CAS CSCD 2009年第3期281-291,共11页
The effect of annual additions of composted sewage sludge (CS) and thermally dried sewage sludge (TS) at 80 t ha-1 on soil chemical properties was investigated for three years in a field experiment under semiarid cond... The effect of annual additions of composted sewage sludge (CS) and thermally dried sewage sludge (TS) at 80 t ha-1 on soil chemical properties was investigated for three years in a field experiment under semiarid conditions. Humic acids (HAs) isolated by conventional procedures from CS, TS, and unamended (SO) and sludge amended soils were analysed for elemental (C, H, N, S and O) and acidic functional groups (carboxylic and phenolic) and by ultraviolet-visible, Fourier transform infrared and fluorescence spectroscopies. With respect to CS, TS had similar pH and total P and K contents, larger dry matter, total organic C, total N and C/N ratio and smaller ash content and electrical conductivity. Amendment with both CS and TS induced a number of modifications in soil properties, including an increase of pH, electrical conductivity, total organic C, total N, and available P. The CS-HA had greater O, total acidity, carboxyl, and phenolic OH group contents and smaller C and H contents than TS-HA. The CS-HA and TS-HA had larger N and S contents, smaller C, O and acidic functional group contents, and lower aromatic polycondensation and humification degrees than SO-HA. Amended soil-HAs showed C, H, N and S contents larger than SO-HA, suggesting that sludge HAs were partially incorporated into soil HAs. These effects were more evident with increasing number of sludge applications. 展开更多
关键词 elemental composition fluorescence spectroscopy Fourier transform infrared spectroscopy functional group composition
下载PDF
Recent advances in the molecular genetics of type 2 diabetes mellitus 被引量:21
12
作者 Antonio Brunetti Eusebio Chiefari Daniela Foti 《World Journal of Diabetes》 SCIE 2014年第2期128-140,共13页
Type 2 diabetes mellitus(T2DM) is a complex disease in which both genetic and environmental factors interact in determining impaired β-cell insulin secretion and peripheral insulin resistance. Insulin resistance in m... Type 2 diabetes mellitus(T2DM) is a complex disease in which both genetic and environmental factors interact in determining impaired β-cell insulin secretion and peripheral insulin resistance. Insulin resistance in muscle, liver and fat is a prominent feature of most patients with T2DM and obesity, resulting in a reduced response of these tissues to insulin. Considerable evidence has been accumulated to indicate that heredity is a major determinant of insulin resistance and T2DM. It is believed that, among individuals destined to develop T2DM, hyperinsulinemia is the mechanism by which the pancreatic β-cell initially compensates for deteriorating peripheral insulin sensitivity, thus ensuring normal glucose tolerance. Most of these people will develop T2DM when β-cells fail to compensate. Despite the progress achieved in this field in recent years, the genetic causes of insulin resistance and T2DM remain elusive.Candidate gene association, linkage and genome-wide association studies have highlighted the role of genetic factors in the development of T2DM. Using these strategies, a large number of variants have been identified in many of these genes, most of which may influence both hepatic and peripheral insulin resistance, adipogenesis and β-cell mass and function. Recently, a new gene has been identified by our research group, the HMGA1 gene, whose loss of function can greatly raise the risk of developing T2DM in humans and mice. Functional genetic variants of the HMGA1 gene have been associated with insulin resistance syndromes among white Europeans, Chinese individuals and Americans of Hispanic ancestry. These findings may represent new ways to improve or even prevent T2DM. 展开更多
关键词 Genome-wide association study candidate gene Genetic variants High-mobility group A1 Insulin resistant diabetes
下载PDF
Effect of land use on soil nematode community composition and co-occurrence network relationship
13
作者 Xiaotong Liu Siwei Liang +3 位作者 Yijia Tian Xiao Wang Wenju Liang Xiaoke Zhang 《Journal of Integrative Agriculture》 SCIE CAS CSCD 2024年第8期2807-2819,共13页
Land use influences soil biota community composition and diversity,and then belowground ecosystem processes and functions.To characterize the effect of land use on soil biota,soil nematode communities in crop land,for... Land use influences soil biota community composition and diversity,and then belowground ecosystem processes and functions.To characterize the effect of land use on soil biota,soil nematode communities in crop land,forest land and fallow land were investigated in six regions of northern China.Generic richness,diversity,abundance and biomass of soil nematodes was the lowest in crop land.The richness and diversity of soil nematodes were 28.8and 15.1%higher in fallow land than in crop land,respectively.No significant differences in soil nematode indices were found between forest land and fallow land,but their network keystone genera composition was different.Among the keystone genera,50%of forest land genera were omnivores-predators and 36%of fallow land genera were bacterivores.The proportion of fungivores in forest land was 20.8%lower than in fallow land.The network complexity and the stability were lower in crop land than forest land and fallow land.Soil pH,NH_(4)^(+)-N and NO_(3)^(–)-N were the major factors influencing the soil nematode community in crop land while soil organic carbon and moisture were the major factors in forest land.Soil nematode communities in crop land influenced by artificial management practices were more dependent on the soil environment than communities in forest land and fallow land.Land use induced soil environment variation and altered network relationships by influencing trophic group proportions among keystone nematode genera. 展开更多
关键词 soil nematode trophic groups community composition co-occurrence network land use
下载PDF
The Effect of Interfacial Interactions on a Structure and Properties of Polyurethane Elastomer/Poly(Vinyl Chloride) Blends 被引量:1
14
作者 T. L. Malysheva S. V. Golovan D. L. Starokadomsky 《Open Journal of Organic Polymer Materials》 2011年第1期1-7,共7页
The effect of chemical structure of segmented poly(urethane-urea)s on its interfacial interactions with poly(vinyl chloride) as well as supramolecular structure and the properties of prepared composites has been studi... The effect of chemical structure of segmented poly(urethane-urea)s on its interfacial interactions with poly(vinyl chloride) as well as supramolecular structure and the properties of prepared composites has been studied. A direct influence of flexible and rigid segments of elastomers on a compatibility, structure and the physical-mechanical properties of poly(urethane-urea)/poly(vinyl chloride) blends was investigated. A formation of intermolecular hydrogen bonds network in the poly(urethane-urea)/poly(vinyl chloride) systems was evaluated by FTIR analysis. Morphology studies have shown the effect of interfacial interactions on a size of thermoplastic phase dispersed within elastomer matrix. Obtained poly(urethane-urea)/poly(vinyl chloride) micro- and nanocomposites have improved tensile properties. 展开更多
关键词 Polymer Composites Compatibility MICROPHASE Separation Glass Transition Hard Domains CRYSTALLITES ASSOCIATES H-BONDS Urethane-Urea groups Interfacial Interactions
下载PDF
Characteristics of carbonatites from the northern part of the Korean Peninsula: A perspective from distribution, geology and geochemistry
15
作者 Jinkon Ju Yunsong Kim Mansik Gang 《Geoscience Frontiers》 SCIE CAS CSCD 2021年第1期173-181,共9页
The present study introduces the carbonatite in the northern part of the Korean Peninsula for the first time.Recent exploration and development of the phosphorus-bearing carbonate rocks in the area have accumulated ne... The present study introduces the carbonatite in the northern part of the Korean Peninsula for the first time.Recent exploration and development of the phosphorus-bearing carbonate rocks in the area have accumulated new geological data which gave us an opportunity to study origin of the carbonate rocks.We conducted geological survey,geochemical analyses of trace elements and rare earth elements,and carbon and oxygen isotope analyses for the carbonatites from Ssangryong,Pungnyon,Yongyu and Puhung districts of the northern part of the Korean Peninsula.This research confirms that the phosphorus-bearing carbonate rocks are carbonatite originating from the mantle.The studied carbonatites are distributed at the junctions of ring and linear structures or around their margins and contain a greater amount of REEs,Y,and Sr than carbonate rocks.The carbonatites in Yongyu and Puhung area show evidence that they were formed from mantle plume generated at the lower mantle and display similar fractionation characteristics to carbonatites in Barrado Itapirapua in Brazil and Kalkfeld and Ondurakorume in Namibia.REE patterns of the carbonatites are typical of carbonatites and the carbon and oxygen isotope analyses demonstrate that the carbonatites were originated from mantle.The carbonatites from the northern part of the Korean Peninsula have a great potential for sources of REE,Y,PGE(platinum group elements),copper,and gold. 展开更多
关键词 CARBONATITE Rare-earth elements Stable isotope composition Phoscorite Platinum group elements Korean Peninsula
下载PDF
The Triggering Role of Carrier Mobility in the Fractional Quantum Hall Effect Formation—An Evidence in Graphene
16
作者 Janusz Jacak Lucjan Jacak 《Journal of Modern Physics》 2013年第12期1591-1596,共6页
Recent experiments with suspended graphene have indicated the crucial role of carrier mobility in the competition between Laughlin collective state and insulating state, probably of Wigner-crystal-type. Moreover, the ... Recent experiments with suspended graphene have indicated the crucial role of carrier mobility in the competition between Laughlin collective state and insulating state, probably of Wigner-crystal-type. Moreover, the fractional quantum Hall effect (FQHE) in graphene has been observed at a low carrier density where the interaction is reduced as a result of particles dilution. This suggests that the interaction may not be a sole factor in the triggering of FQHE as it was expected basing on the standard formulation of the composite fermion model. Here, the topological arguments are presented to explain the observed features of the FQHE in graphene and the triggering role of carrier mobility in formation of the Laughlin state. 展开更多
关键词 GRAPHENE FQHE Braid groups Composite Fermions
下载PDF
Components of Paraffin-Base and Naphthenic-Base Crude Oil and Their Effects on Interfacial Performance
17
作者 Zhu Yin Pingnan Yuan +2 位作者 Xiang Lian Yancheng Zheng Heng Zheng 《Open Journal of Yangtze Oil and Gas》 2019年第4期270-284,共15页
The saturate,aromatics,resin and asphaltene components of paraffin-base(PB)and naphthenic-base(HB)crude oil are separated by chromatographic column.The acidic components of crude oil are extracted by compounded polar ... The saturate,aromatics,resin and asphaltene components of paraffin-base(PB)and naphthenic-base(HB)crude oil are separated by chromatographic column.The acidic components of crude oil are extracted by compounded polar solvents and identified by methyl esterification of diazomethane.The acidic components before and after asphaltene removal are investigated by gas chromatography-mass spectrometer.The effect of four fractions in simulated oil on interfacial activity is discussed.The results show PB is rich in naphthalene series and tri-aromatic steroids,and HB has a high content of phenanthrene series,chrysene series and methylpyrene,besides higher content of naphthalene series.The long carbon chain acids in HB oil decrease significantly by asphaltenes removal,confirming the presence of heavy oil acids in asphaltene.A little amount of saturates and aromatics in simulated oil can reduce the interfacial tension(IFT).When the content of asphaltenes of simulated oil is increased,IFT is initially decreased and finally increased because of stability of asphaltenes.When resin is increased,IFT is initially increased and then decreased.Simulated oil containing the resin from naphthenic-base oil is more sensitive to alkali than that of paraffin-base resin,which can reduce the IFT between oil and water at a larger range. 展开更多
关键词 Component Separation Carboxylic Acids group composition Paraffin-Base OIL Naphthenic-Base OIL INTERFACIAL Activity
下载PDF
Comprehensive characterization of yam tuber nutrition and medicinal quality of Dioscorea opposita and D.alata from different geographic groups in China 被引量:16
18
作者 SHAN Nan WANG Pu-tao +7 位作者 ZHU Qiang-long SUN Jing-yu ZHANG Hong-yu LIU Xing-yue CAO Tian-xu CHEN Xin HUANG Ying-jin ZHOU Qing-hong 《Journal of Integrative Agriculture》 SCIE CAS CSCD 2020年第11期2839-2848,共10页
China is an important domestication center of yams,and two main yam species of Dioscorea opposita and D.alata are commonly cultivated in China.However,the differences of nutritional and medicinal characteristics betwe... China is an important domestication center of yams,and two main yam species of Dioscorea opposita and D.alata are commonly cultivated in China.However,the differences of nutritional and medicinal characteristics between the two species and their subgroups remain unclear,which would greatly affect the resource conservation and commercial utilization of yams.In this study,typical yam resources including the species of D.opposita(wild and cultivated Ruichang yam from southern China,and Tiegun yam from northern China)and two landraces of D.alata(Longyan yam and Anyuan yam from southern China)were selected as materials.Nutritional traits and medicinal characteristics were determined and analyzed respectively.The results showed that there was no significant differences in the content of most nutrients between D.opposita and D.alata,but most cultivated Ruichang yam of D.opposita showed higher levels of starch,soluble sugar,sucrose,and ascorbate in tuber than that in yam from D.alata.Moreover,an UPLC-MS method was developed for identification and determination of medicinal characteristics in the two species.The results showed that allantoin can be detected in all selected samples.Cultivated Ruichang yam of D.opposita possessed the highest allantoin content among the tested materials,and was significantly different with that in Tiegun yam and D.alata.Dioscin was not detected in D.alata.Overall,there was little difference in nutritional composition between D.opposita and D.alata,but the medicinal quality of D.opposita was better than that of D.alata.Due to the outstanding comprehensive quality,the local variety of cultivated Ruichang yam can be further developed and utilized. 展开更多
关键词 geographic groups yam tuber nutritional traits UPLC-MS medicinal composition
下载PDF
Taipingite-(Ce),(Ce73+,Ca2)∑9Mg(SiO4)3[SiO3(OH)]4F3,a new mineral from the Taipingzhen REE deposit,North Qinling Orogen,central China 被引量:1
19
作者 Kai Qu Xianzhang Sima +7 位作者 Guang Fan Guowu Li Ganfu Shen Huakai Chen Xing Liu Qingqing Yin Ting Li Yanjuan Wang 《Geoscience Frontiers》 SCIE CAS CSCD 2020年第6期2339-2346,共8页
A new cerite group mineral species,taipingite-(Ce),ideally(Ce7^3+,Ca2)∑9Mg(SiO4)3[SiO3(OH)]4 F3,has been found in the Taipingzhen rare earth element(REE)deposit in the North Qinling Orogen(NQO),Central China.It forms... A new cerite group mineral species,taipingite-(Ce),ideally(Ce7^3+,Ca2)∑9Mg(SiO4)3[SiO3(OH)]4 F3,has been found in the Taipingzhen rare earth element(REE)deposit in the North Qinling Orogen(NQO),Central China.It forms subhedral grains(up to approximately 100 μm×200 μm)commonly intergrown with the REE mineral assemblages and is closely associated with allanite-(Ce),gatelite-(Ce),tornebohmite-(Ce),fluocerite-(Ce),fluocerite-(La),fluorite,bastnasite-(Ce),parisite-(Ce)and calcite.Taipingite-(Ce)is light red to pinkish brown under a binocular microscope and pale brown to colorless in thin section,and it is translucent to transparent with a grayish-white streak and vitreous luster.This mineral is brittle with conchoidal fracture;has a Mohs hardness value of approximately 51/2 and exhibits no cleavage twinning or parting.The calculated density is 4.900(5)g/cm3.Optically,taipingite-(Ce)is uniaxial(+),withω=1.808(5),ε=1.812(7),c=ε,and a=b=ω.Furthermore,this mineral is insoluble in HCl,HNO3 and H2 SO4.Electron microprobe analysis demonstrated that the sample was relatively pure,yielding the empirical formula(with calculated H2 O):(Ce4.02La1.64Nd1.49Pr0.41Sm0.10Gd0.02Ho0.02Tm0.01Lu0.02Y0.03Ca0.66Mg0.05Th(0.01-0.51∑9(Mg0.75Fe0.253+)∑1(SiO4)3{[SiO3(OH)]3.98[PO3(OH)]0.02}∑4(F1.81OH1.17Cl0.02∑3.Taipingite-(Ce)is trigonal and exhibits space group symmetry R3 c with unit cell parameters a=10.7246(3)Å,c=37.9528(14)Å,V=3780.39(20)Å3 and Z=6.The strongest eight lines in the X-ray diffraction pattern are[d in A(I)(hkl)]:4.518(50)(202),3.455(95)(122),3.297(85)(214),3.098(35)(300),2.941(100)(02,10),2.683(65)(220),1.945(40)(238)and 1.754(40)(30,18).The crystal structure has been refined to a R1 factor of 0.025,calculated for the 2312 unique observed reflections(Fo≥4σ).The mineral is named after its discovery locality and is characterized as the F-dominant analogue of cerite-(Ce). 展开更多
关键词 Taipingite-(Ce) Cerite group New mineral species Chemical composition Crystal structure North Qinling Orogen
下载PDF
Research on the Terrane Tectonics in China 被引量:1
20
作者 郭令智 舒良树 +4 位作者 施央申 卢华复 马瑞士 张庆龙 贾东 《Chinese Journal Of Geochemistry》 EI CAS 1996年第3期193-202,共10页
This paper summarizes the lalest advances in research on the terrane tectonics of China. The terranes of China distributed around various plates may be divided into four terrane belts of different ages and sizes, i. e... This paper summarizes the lalest advances in research on the terrane tectonics of China. The terranes of China distributed around various plates may be divided into four terrane belts of different ages and sizes, i. e., the East China, Northwest China, Southwest China and Qinling-Dabie terrane belts. Among them, the East China belt may be subdivided into three composite terrane groups; each terrane group is composed of several terranes that were formed roughly at the same time and have distinct geologic histories. The accretion of China’s terranes involves three types: the collision type, the flake-thrusting type, and the docking type. The results of the latest study in the five widening fields and some advances in the metheds of research on the terrane tectonics in China are presented in the present paper. 展开更多
关键词 岩层构造 中国 秦岭-大别山地区 地质构造 华东地区 西北地区 西南地区
下载PDF
上一页 1 2 39 下一页 到第
使用帮助 返回顶部