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明代哈密“哈剌灰”及其与裕固族关系考辨
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作者 杨富学 海霞 《内蒙古社会科学》 北大核心 2024年第3期77-83,F0002,共8页
关于明代文献所见哈密“哈剌灰”之名与义,学界多有争议。揆诸《华夷译语·委兀儿译语·地名》中有“黑羊群—噶剌塊”之谓,可以推定“哈剌灰”这一称谓应出自维吾尔语qaraqoi,意为“黑羊群”。作为蒙古豳王家族的属部,元明时... 关于明代文献所见哈密“哈剌灰”之名与义,学界多有争议。揆诸《华夷译语·委兀儿译语·地名》中有“黑羊群—噶剌塊”之谓,可以推定“哈剌灰”这一称谓应出自维吾尔语qaraqoi,意为“黑羊群”。作为蒙古豳王家族的属部,元明时期哈剌灰一直与信仰伊斯兰教的回回和信仰佛教的畏兀儿共处哈密,经历了由伊斯兰教改宗佛教的过程。“哈剌灰”指的就是1276年以后由中亚迁居哈密原本信仰伊斯兰教后皈依佛教的蒙古人。他们在皈依藏传佛教后,仍葆有浓重的伊斯兰文化情结。明正德年间,东迁河西走廊,后融合于裕固族之中。 展开更多
关键词 哈剌灰 蒙古豳王 安定王 宗教信仰
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20个玉米品种在安定区的适应性研究及营养价值评价
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作者 杨文静 赵聖明 +2 位作者 王霞 樊霞 蓝志斌 《饲料研究》 CAS 北大核心 2024年第8期143-149,共7页
试验于2021年-2022年对20个玉米品种的生产性能和饲用品质进行综合评价,旨在筛选出适宜安定区或同类地区种植的青贮玉米品种。2021年对20个参试玉米品种的株高、茎粗、叶片数、单株重、果穗长、果穗粗和穗行数等农艺性状和饲草产量进行... 试验于2021年-2022年对20个玉米品种的生产性能和饲用品质进行综合评价,旨在筛选出适宜安定区或同类地区种植的青贮玉米品种。2021年对20个参试玉米品种的株高、茎粗、叶片数、单株重、果穗长、果穗粗和穗行数等农艺性状和饲草产量进行测定,利用隶属函数法对其营养成分进行综合分析,并结合饲草相对饲喂价值(RFV)和饲草分级指数(GI),对参试品种进行综合评价,初步筛选出兴贮88、先玉1321、中农大2118、京科青贮516、京科968、京九青贮16、同康1号、京科青贮932和先玉1225共9个综合指标较好的品种,于2022年进行第二次试验。2022年采用同样的方法对选出的9个参试品种进一步综合评价,结果表明:京科青贮932、京科青贮516、京九青贮16和兴贮88的适应性好,农艺性状和产量优异,相对饲用价值较高,适宜在安定区或者同类地区推广种植。 展开更多
关键词 玉米品种 安定区 适应性研究 营养价值评价
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高性能材料和耐久性设计在大跨度斜拉桥中的应用与实践
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作者 林全富 《交通节能与环保》 2024年第4期234-238,共5页
高性能材料和工艺的应用,是一种理念创新,也是一种技术创新。本文采用实证分析法,论述了高性能耐久材料在大跨度斜拉桥中的应用细节与实施效果,得到如下结论:高性能混凝土的应用可以极大地提高材料使用效率,减小断面尺寸和结构自重,简... 高性能材料和工艺的应用,是一种理念创新,也是一种技术创新。本文采用实证分析法,论述了高性能耐久材料在大跨度斜拉桥中的应用细节与实施效果,得到如下结论:高性能混凝土的应用可以极大地提高材料使用效率,减小断面尺寸和结构自重,简化结构配筋,简化施工流程,适合各类结构形式与安装方法,特别是在钢-混组合结构中,其优点更加突出;采用高强度钢结构可以有效降低构件的自身重量,降低施工难度;综合长效防腐体系的斜拉索有效满足了桥梁的耐久性和抗风动力性能需求,有效兼顾了运营期构件更换的便利性,对交通限制时间更短、影响更小;新型高性能桥墩防船撞消能装置的正撞碰撞力消减幅度达38.0%。 展开更多
关键词 高性能材料 耐久性设计 大跨度斜拉桥 全生命周期 提质降碳
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2023年甘肃省安定区牛羊布鲁氏菌病的流行病学调查
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作者 张玲萍 马永国 +1 位作者 田华 王振华 《养殖与饲料》 2024年第7期69-72,共4页
[目的]明确甘肃安定区牛羊布鲁氏菌病的感染状况及流行趋势,分析疫情发生的原因和传播途径,为制定针对性的防控措施提供科学依据。[方法]从安定区牛羊规模化养殖场和散养户中随机抽取未进行布病免疫接种的牛羊,2023年1-12月共采集21 01... [目的]明确甘肃安定区牛羊布鲁氏菌病的感染状况及流行趋势,分析疫情发生的原因和传播途径,为制定针对性的防控措施提供科学依据。[方法]从安定区牛羊规模化养殖场和散养户中随机抽取未进行布病免疫接种的牛羊,2023年1-12月共采集21 010份血清样本,其中羊血清样本为13 284份,牛血清样本为7 726份。对安定区牛羊布鲁氏菌病流行病学进行分析,结合实验室检测,确诊疑似病例。[结果]在不同的养殖场地中,种畜场阳性检出率最低,其中种羊场总阳性检出率为0.11%,种牛场总阳性检出率为0。在1年监测周期内,羊布病在3、9、10月的阳性检出率较高,分别为0.37%、0.36%、0.27%;牛布病在4、8、9月阳性检出率较高,分别为0.28%、0.32%、0.31%。[结论]在春秋季节,牛羊布病更容易流行,因此应从监测净化、消毒灭源、养殖管理等方面入手,采取有效的防控措施,减轻牛羊布病的危害。 展开更多
关键词 安定区 牛羊布鲁氏菌病 流行病学调查 布病净化 防控措施
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针对ANDES油田的抗高温高盐二元复合驱油体系研究 被引量:2
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作者 庄天琳 宋考平 +2 位作者 赵宇 王纪伟 宋丽阳 《油田化学》 CAS CSCD 北大核心 2015年第3期392-395,共4页
ANDES油田属于高温(96℃)、高盐(71.5 g/L)油藏。在此条件下,将耐温耐盐理想的疏水缔合聚合物AP-P5与4种表面活性剂复配,发现0.3%的磺酸盐(MJ2)或大庆石油磺酸盐(DQ)与2500mg/LAP-P5形成的二元体系界面张力可以达到10^(-3)mN/m数量级。... ANDES油田属于高温(96℃)、高盐(71.5 g/L)油藏。在此条件下,将耐温耐盐理想的疏水缔合聚合物AP-P5与4种表面活性剂复配,发现0.3%的磺酸盐(MJ2)或大庆石油磺酸盐(DQ)与2500mg/LAP-P5形成的二元体系界面张力可以达到10^(-3)mN/m数量级。考察了温度、矿化度对这两种二元复合体系黏度的影响。结果表明,两种二元复合体系黏度随着温度、矿化度的增加而降低。在96℃、矿化度为70 g/L的条件下,3000 mg/L AP-P5+0.3%MJ2+稳定剂硫脲二元复合体系的黏度为99.4mPa·s,达到现场要求。并且该二元体系在此条件下放置两个月后,黏度趋于稳定,界面张力波动幅度不大。室内物理模拟驱油实验中,当二元复合体系注入体积为0.65 PV时,采收率增幅最大(24.5%)。前期水驱至含水85%+0.65 PV(3000 mg/L AP-P5+0.3%MJ2)+后期水驱至出口含水98%为最佳驱油方案。 展开更多
关键词 andES油田 高温高盐 二元复合驱 疏水缔合聚合物 表面活性剂
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Early-Middle Paleozoic Andes-type Continental Margin in the Chifeng Area, Inner Mongolia: Framework, Geochronology and Geochemistry and Implications for Tectonic Evolution of the Central Asian Orogenic Belt 被引量:5
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作者 YAN Linjie XU Bei +1 位作者 ZHANG Jiaming WANG Yanyang 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2020年第1期57-74,共18页
Three tectonic units have been recognized in the Chifeng area, Inner Mongolia, from north to south, including the Qiganmiao accretionary prism, Jiefangyingzi arc belt and Sidaozhangpeng molasse basin, which formed an ... Three tectonic units have been recognized in the Chifeng area, Inner Mongolia, from north to south, including the Qiganmiao accretionary prism, Jiefangyingzi arc belt and Sidaozhangpeng molasse basin, which formed an Andeantype active continent margin during the early to middle Paleozoic. The Qiganmiao accretionary prism is characterized by a mélange that consists of gabbro, two-mica quartz schist and basic volcanic rock blocks and heterogeneously deformed marble matrix. Two zircon U-Pb ages of 446.0±6.3 Ma and 1104±27 Ma have been acquired and been interpreted as the metamorphic and forming ages for the gabbro and two-mica quartz schist, respectively. The prism formed during the early to middle Paleozoic southward subduction of the Paleo Asian Ocean(PAO) and represents a suture between the North China craton(NCC) and Central Asian Orogenic Belt(CAOB). The Jiefangyingzi arc belt consists of pluton complex and volcanic rocks of the Xibiehe and Badangshan Formations, and Geochronology analysis indicates that the development of it can be divided into two stages. The first stage is represented by the Xibiehe Formation volcanic rocks, which belong to the subalkaline series, enriched LREE and LILE and depleted HFSE, with negative Eu anomalies, and plot in the volcanic arc field in discrimination diagrams. These characters indicate that the Xibiehe Formation results from to the continental arc magmatic activity related to the subduction of the PAO during 400–420 Ma. Magmatism of the second stage in 380–390 Ma consists of the Badangshan Formation volcanic rocks. Geochemistry analysis reveals that rhyolite, basaltic andesite and basalt of the Badangshan Formation were developed in continental margin arc setting. Moreover, the basaltic andesite and basalt display positive Sr anomalies, and the basalt have very low Nb/La values, suggesting that fluid is involved in magma evolution and the basalts were contaminated by continental crust. The sequence of Sidaozhangpeng molasse basin is characterized by proximity, coarseness and large thickness, similar to the proximity molasses basin. According to our field investigation, geochronological and geochemical data, combined with previous research in this area, a tectonic evolutionary model for Andes-type active continental margin of the CAOB has been proposed, including a development of the subduction-free PAO before 446 Ma, a subduction of the PAO and arc-related magmatism during 446–380 Ma, and formation of a molasse basin during 380–360 Ma. 展开更多
关键词 Chifeng area andes-type continental margin early-middle PALEOZOIC tectonic evolution Central Asian OROGENIC Belt
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Finite element modelling of the geodynamic processes of the Central Andes subduction zone:A Reference Model 被引量:2
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作者 Chris Salomon 《Geodesy and Geodynamics》 2018年第3期246-251,共6页
This paper presents preliminary results of three-dimensional thermomechanical finite-element models of a parameter study to compute the current temperature and stress distribution in the subduction zone of the central... This paper presents preliminary results of three-dimensional thermomechanical finite-element models of a parameter study to compute the current temperature and stress distribution in the subduction zone of the central Andes (16°S-26°S) up to a depth of 400 km, the bottom of the asthenosphere. For this purpose a simulation running over c. 50,000 years will be realized based on the geometry of a generic subduction zone and an elasto-viscoplastic Drucker-Prager rheology. The kinematic and thermal boundary conditions as well as the rheological parameters represent the current state of the study area. In future works the model will be refined using a systematic study of physical parameters in order to estimate the influence of the main parameters (e.g. viscosity, fault friction, velocity, shear heating) on the results of the reference model presented here. The reference model is kept as simple as possible to be able to estimate the influence of the parameters in future studies in the best possible way, whilst minimizing comnutational time. 展开更多
关键词 ABAQUS andes subduction zone Finite element modelling Thermomechanical models VISCOPLASTICITY
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Bank erosion in an Andean páramo river system: Implications for hydro-development and carbon dynamics in the neotropical Andes 被引量:1
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作者 Derek J.MARTIN Christopher ELY Beverley C.WEMPLE 《Journal of Mountain Science》 SCIE CSCD 2019年第2期243-255,共13页
The páramo of the Northern Andes provide critically important ecosystem services to the Northern Andean region in the form of water provisioning and carbon sequestration, both of which are a result of the pá... The páramo of the Northern Andes provide critically important ecosystem services to the Northern Andean region in the form of water provisioning and carbon sequestration, both of which are a result of the páramo?s organic-rich soils. Little is known, however, about the hydro-geomorphic characteristics of the rivers that drain these ecosystems. With impending plans for widespread hydro-development and increasing implementation of carbon-sequestering compensation for ecosystem services programs in the region it is imperative that we develop a thorough understanding of the hydrogeomorphic role that rivers play in this unique ecosystem. The objective of this study was to quantify bank erosion along an Amazonian headwater stream draining a small, relatively undisturbed páramo catchment to gain a better understanding of the natural erosion regime and the resulting sediment contributions from this unique ecosystem. This study implemented a combination of field, laboratory, and Geographic Information Systems techniques to quantify bank erosion rates and determine a bank erosion sediment yield from the Ningar River, a small páramo catchment(22.7 km^2) located in the eastern Andean cordillera of Ecuador. Results show that bank erosion rates range from 3.0 to ≥ 390.0 mm/yr, are highly episodic, and yield at least 487 tons of sediment annually to the Ningar River. These results imply that 1) páramo ecosystems substantially contribute to the sediment load of the Amazon River basin; 2) bank erosion is a potentially significant flux component of basin-scale carbon cycles in páramo ecosystems; and 3) hydrologic alteration campaigns(dam building) will likely critically alter these contributions and concomitantly disconnect a critical source of sediment and nutrients to downstream ecosystems. 展开更多
关键词 BANK EROSION Páramo FLUVIAL GEOMORPHOLOGY andES
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An Andean tectonic cycle:From crustal thickening to extension in a thin crust(34°-37°SL) 被引量:2
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作者 Victor A.Ramos Vanesa D.Litvak +1 位作者 Andrés Folguera Mauro Spagnuolo 《Geoscience Frontiers》 SCIE CAS CSCD 2014年第3期351-367,共17页
Several orogenic cycles of mountain building and subsequent collapse associated with periods of shal- lowing and steepening of subduction zones have been recognized in recent years in the Andes. Most of them are chara... Several orogenic cycles of mountain building and subsequent collapse associated with periods of shal- lowing and steepening of subduction zones have been recognized in recent years in the Andes. Most of them are characterized by widespread crustal delamination expressed by large calderas and rhyolitic flare-up produced by the injection of hot asthenosphere in the subduction wedge. These processes are related to the increase of the subduction angle during trench roll-back. The Payenia paleoflat-slab, in the southern Central Andes of Argentina and Chile (34° -37°S) recorded a complete cycle from crustal thickening and mountain uplift to extensional collapse and normal faulting, which are related to changes in the subduction geometry. The early stages are associated with magmatic expansion and migration, subsequent deformation and broken foreland. New ages and geochemical data show the middle to late Miocene expansion and migration of arc volcanism towards the foreland region was associated with important deformation in the Andean foothills. However, the main difference of this orogenic cycle with the previously described cycles is that the steepening of the oceanic subducted slab is linked to basaltic flooding of large areas in the retroarc under an extensional setting. Crustal delamination is concentrated only in a narrow central belt along the cordilleran axis. The striking differences between the two types of cycles are interpreted to be related to the crustal thickness when steepening the subducting slab, The crustal thickness of the Altiplano is over 60-80 km, whereas Payenia is less than 42 km in the axial part, and near 30 km in the retroarc foothills. The final extensional regime associated with the slab steepening favors the basaltic flooding of more than 8400 km3 in an area larger than 40,000 km2, through 800 central vents and large fissures. These characteristics are unique in the entire present-day Andes. 展开更多
关键词 andes Retroarc magmatism Basaltic floods Crustal delamination Flat-slab
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Phylogeny and evolution of Perezia(Asteraceae:Mutisieae:Nassauviinae)
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作者 Beryl B.SIMPSON Mary T.K.ARROYO +2 位作者 Sandra SIPE Marta DIAS de MORAES Joshua McDILL 《Journal of Systematics and Evolution》 SCIE CSCD 北大核心 2009年第5期431-443,共13页
A molecular phylogenetic analysis of most of the species of Perezia reveals that, as traditionally defined, the genus is not monophyletic with two species more closely related to Nassauvia than to Perezia. In addition... A molecular phylogenetic analysis of most of the species of Perezia reveals that, as traditionally defined, the genus is not monophyletic with two species more closely related to Nassauvia than to Perezia. In addition, our results show that Burkartia (Perezia) lanigera is related to Acourtia and is the only member of that clade in South America. The remaining species are monophyletic and show a pattern of an early split between a western temperate and an eastern subtropical clade of species. Within the western clade, the phylogeny indicates a pattern of diversification that proceeded from southern, comparatively low-elevation habitats to southern high-elevation habitats, and ultimately into more northern high-elevation habitats. The most derived clades are found in the high central Andes, where significant radiation has occurred. 展开更多
关键词 andES BIOGEOGRAPHY MUTISIEAE Nassauviinae Perezia.
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Cenozoic basin evolution of the Central Patagonian Andes:Evidence from geochronology, stratigraphy, and geochemistry
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作者 A.Encinas A.Folguera +6 位作者 R.Riffo P.Molina L.Fernández Paz V.D.Litvak D.A.Colwyn V.A.Valencia M.Carrasco 《Geoscience Frontiers》 SCIE CAS CSCD 2019年第3期1139-1165,共27页
The Central Patagonian Andes is a particular segment of the Andean Cordillera that has been subjected to the subduction of two spreading ridges during Eocene and Neogene times. In order to understand the Cenozoic geol... The Central Patagonian Andes is a particular segment of the Andean Cordillera that has been subjected to the subduction of two spreading ridges during Eocene and Neogene times. In order to understand the Cenozoic geologic evolution of the Central Patagonian Andes, we carried out geochronologic(U-Pb and^(40)Ar/^(39)Ar), provenance, stratigraphic, sedimentologic, and geochemical studies on the sedimentary and volcanic Cenozoic deposits that crop out in the Meseta Guadal and Chile Chico areas(~47°S). Our data indicate the presence of a nearly complete Cenozoic record, which refutes previous interpretations of a hiatus during the middle Eocene-late Oligocene in the Central Patagonian Andes. Our study suggests that the fluvial strata of the Ligorio Marquez Formation and the flood basalts of the Basaltos Inferiores de la Meseta Chile Chico Formation were deposited in an extensional setting related to the subduction of the Aluk-Farallon spreading ridge during the late Paleocene-Eocene. Geochemical data on volcanic rocks interbedded with fluvial strata of the San Jose Formation suggest that this unit was deposited in an extensional setting during the middle Eocene to late Oligocene. Progressive crustal thinning allowed the transgression of marine waters of Atlantic origin and deposition of the upper Oligocene-lower Miocene Guadal Formation. The fluvial synorogenic strata of the Santa Cruz Formation were deposited as a consequence of an important phase of compressive deformation and Andean uplift during the early-middle Miocene. Finally, alkali flood basalts of the late middle to late Miocene Basaltos Superiores de la Meseta Chile Chico Formation were extruded in the area in response to the suduction of the Chile Ridge under an extensional regime. Our studies indicate that the tectonic evolution of the Central Patagonian Andes is similar to that of the North Patagonian Andes and appears to differ from that of the Southern Patagonian Andes, which is thought to have been the subject of continuous compressive deformation since the late Early Cretaceous. 展开更多
关键词 CENTRAL Patagonian andES U-Pb GEOCHRONOLOGY Ar-Ar GEOCHRONOLOGY GEOCHEMISTRY STRATIGRAPHY SEDIMENTOLOGY
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Petrogenesis of Quebrada de la Mina and Altar North porphyries (Cordillera of San Juan, Argentina): Crustal assimilation and metallogenic implications
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作者 Laura Maydagán Marta Franchini +4 位作者 Massimo Chiaradia Verónica Bouhier Noelia Di Giuseppe Roger Rey Luis Dimieri 《Geoscience Frontiers》 SCIE CAS CSCD 2017年第5期1135-1159,共25页
We investigate the geology of Altar North(Cu-Au) and Quebrada de la Mina(Au) porphyry deposits located in San Juan Province(Argentina), close to the large Altar porphyry copper deposit(995 Mt,0.35% Cu, 0.083 g/t Au), ... We investigate the geology of Altar North(Cu-Au) and Quebrada de la Mina(Au) porphyry deposits located in San Juan Province(Argentina), close to the large Altar porphyry copper deposit(995 Mt,0.35% Cu, 0.083 g/t Au), to present constraints on the magmatic processes that occurred in the parental magma chambers of these magmatic-hydrothermal systems. Altar North deposit comprises a plagioclase-amphibole-phyric dacite intrusion(Altar North barren porphyry) and a plagioclaseamphibole-biotite-phyric dacite stock(Altar North mineralized porphyry, 11.98 ± 0.19 Ma). In Quebrada de la Mina, a plagioclase-amphibole-biotite-quartz-phyric dacite stock(QDM porphyry,11.91±0.33 Ma) crops out. High Sr/Y ratios(92-142) and amphibole compositions of Altar North barren and QDM porphyries reflect high magmatic oxidation states(fO_2= NNO+1.1 to+1.6) and high fH_2O conditions in their magmas. Zones and rims enriched in anorthite(An_(37-48))), SrO(0.22-0.33 wt.%)and FeO(0.21-0.37 wt.%) in plagioclase phenocrysts are evidences of magmatic recharge processes in the magma chambers. Altar North and Quebrada de la Mina intrusions have relatively homogeneous isotopic compositions(^(87)Sr/^(86)Sr_(t)= 0.70450-0.70466, ε_(ND)(t) = +0.2 to +1.2) consistent with mixed mantle and crust contributions in their magmas. Higher Pb isotopes ratios(^(207)Pb/^(204)Pb=15.6276-15.6294) of these intrusions compared to other porphyries of the district, reflect an increase in the assimilation of high radiogenic Pb components in the magmas. Ages of zircon xenocrysts(297,210,204,69 Ma) revealed that the magmas have experienced assimilation of Miocene, Cretaceous, Triassic and Carboniferous crustal rocks.Fluids that precipitated sulfides in the Altar deposit may have remobilized Pb from the host rocks, as indicated by the ore minerals being more radiogenic(207Pb/204 Pb = 15.6243-15.6269) than their host intrusions. Au/Cu ratio in Altar porphyries(average Au/Cu ratio of 0.14 ×10^(-4)by weight in Altar Central)is higher than in the giant Miocene porphyry deposits located to the south: Los Pelambres, Rio Blanco and Los Bronces(Chile) and Pachon(Argentina). We suggest that the increase in Au content in the porphyries of this region could be linked to the assimilation of high radiogenic Pb components in the magmas within these long-lived maturation systems. 展开更多
关键词 Porphyry High SULFIDATION EPITHERMAL Magmatic recharge Radiogenic isotopes Crustal assimilation Argentinian andES
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Glacier retreat, rock weathering and the growth of lichensin the Churup Valley, Peruvian Tropical Andes
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作者 Adam EMMER Anna JURICOVA Bijeesh Kozhikkodan VEETTIL 《Journal of Mountain Science》 SCIE CSCD 2019年第7期1485-1499,共15页
The most heavily glacierized tropical range in the world– the Peruvian Cordillera Blanca-has been losing ice since the end of the Little Ice Age(LIA).In this study,the decline of the Churup glacier(9°28’18"... The most heavily glacierized tropical range in the world– the Peruvian Cordillera Blanca-has been losing ice since the end of the Little Ice Age(LIA).In this study,the decline of the Churup glacier(9°28’18"S;77°25’02"W)and associated processes were documented employing multi-proxy approach including the analysis of remotely sensed images(1948-2016),the Schmidt hammer rock test and lichenometric dating.It is shown that Churup glacier has lost the vast majority of its estimated LIA extent(1.05±0.1 km^2;45.0×10^6-57.4×10^6 m^3).The rate of glacier retreat is documented to vary in space(SE,SW and NW-facing slopes)and time,with the peak between 1986 and 1995.With an area of 0.045 km^2 in 2016,it is expected that the complete deglaciation of the Churup valley is inevitable in the near future.Recently(post-LIA)exposed bedrock surfaces have shown higher R-values(54.2-66.4,AVG 63.3,STDEV 2.9)compared to pre-LIA exposed surfaces(46.1-59.3,AVG 50.1,STDEV 4.9),confirming the links to the duration of rock weathering.The Lichenometric dating is applied to recently exposed areas and elevations above 4800 m a.s.l.,revealing only limited reliability and agreement with the age of deglaciation estimated from remotely-sensed images in such an environment. 展开更多
关键词 CORDILLERA Blanca Tropical glaciers DEGLACIATION Geoenvironmental change Lichenometry Rhizocarpon geographicum SCHMIDT HAMMER andES
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Phylogeny and putative hybridization in the subtribe Paranepheliinae (Liabeae, Asteraceae), implications for classification, biogeography, and Andean orogeny
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作者 Akiko SOEJIMA Jun WEN +1 位作者 Mario ZAPATA Michael O. DILLON 《植物分类学报》 CSCD 北大核心 2008年第3期375-390,共16页
The nuclear ribosomal ITS region and the chloroplast trnL-trnF (trnLF) intergenic region were se-quenced for 45 accessions of Paranephelius and six accessions of Pseudonoseris, the two genera of the subtribe Paranephe... The nuclear ribosomal ITS region and the chloroplast trnL-trnF (trnLF) intergenic region were se-quenced for 45 accessions of Paranephelius and six accessions of Pseudonoseris, the two genera of the subtribe Paranepheliinae (Liabeae, Asteraceae) distributed in the alpine regions of the Andes. This data set was used to estimate relationships between these genera and within each genus to aid in evaluating morphological variation and classification. Our results with both ITS and trnLF markers support the monophyly of subtribe Paranephelii-nae, and place Pseudonoseris discolor as the first diverged taxon sister to the clade containing Paranephelius. Pseudonoseris szyszylowiczii exhibited intraspecific divergence supporting intergeneric hybridization between Pseudonoseris and Paranephelius. Within Paranephelius, genetic divergence is low and not adequate to fully resolve phylogenetic relationships at the species level, but two genetically and morphologically recognizable groups were revealed by the ITS data. Several accessions possessing multiple ITS sequences represent putative hybrids between the two groups. These putative hybrids have caused some taxonomic confusion and difficulties in establishing species boundaries in Paranephelius. The divergence time estimates based on ITS sequences indi-cated that the stem of subtribe Paranepheliinae dates to 13 million years ago, but the diversification of the crown clade of the extant members began in the early Pleistocene or late Pliocene, perhaps associated with the uplift of the Andes and the climatic changes of global cooling. 展开更多
关键词 系统演化 杂交 生物地理学 安第斯山脉 造山运动
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Effects of Conservation Tillage on Total and Aggregated Soil Organic Carbon in the Andes
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作者 Marcela Quintero Nicholas B. Comerford 《Open Journal of Soil Science》 2013年第8期361-373,共13页
Many Andisols of the Andes have been disturbed by traditional potato-based rotation agriculture disrupting soil structure, water retention capacity and organic matter content. This study was undertaken to investigate ... Many Andisols of the Andes have been disturbed by traditional potato-based rotation agriculture disrupting soil structure, water retention capacity and organic matter content. This study was undertaken to investigate the contribution of conservation farming technology or reduced tillage in potato-based rotations in the Colombian Andes in order to rehabilitate total and aggregated soil organic C in disturbed organic matter-rich Andisols. Soils were sampled from farms with 7-year of reduced tillage and farms with conventional farming practices. Ultrasound energy was applied to samples to disrupt aggregation and total soil C was determined in order to investigate the amount of carbon held inside the aggregates of different soil size classes. Results indicated that reduced tillage in potato-based crop rotations increased the soil C concentration and average C content in the whole profile (≈117 cm depth) by 50 and 33% (1636 t C ha?1 vs. 1224 t C ha?1), respectively, as compared to conventional farming practices. Carbon content increased 177% in the subsoil (A2 horizon, 78 -117 cm depth, from 215 to 596 t?ha?1), although most of the soil C was in the A1 horizon (between 0 -78 cm average thickness, 1097 t?ha?1). These increases show that reduced tillage enhances C stores in Andisols which are already high in organic matter. In addition, C in aggregates represented more than 80% of the total organic matter and it was positively affected by conservation practices. The C increase was preferential in the smaller macroaggregates ( 展开更多
关键词 Conservation TILLAGE SOIL Organic Carbon SOIL AGGREGATES andES POTATO
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Achieving exceptionally high strength and rapid degradation rate of Mg-Er-Ni alloy by strengthening with lamellar γ' and bulk LPSO phases 被引量:1
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作者 Chaoneng Dai Jingfeng Wang +7 位作者 Yuanlang Pan Kai Ma Yinhong Peng Ye Wang Danqian Wang Chunhua Ran Jinxing Wang Yanlong Ma 《Journal of Materials Science & Technology》 SCIE EI CAS CSCD 2024年第1期88-102,共15页
As-extruded Mg-Er-Ni alloys with different volume fractions of long-period stacking ordered(LPSO)phase and density of lamellar γ' phase were prepared,and the microstructure,mechanical,and degradation properties w... As-extruded Mg-Er-Ni alloys with different volume fractions of long-period stacking ordered(LPSO)phase and density of lamellar γ' phase were prepared,and the microstructure,mechanical,and degradation properties were investigated.Coupling the bulk LPSO phase and the lamellar γ' phase,and controlling the dynamic recrystallization processes during deformation by adjusting the volume fraction of LPSO and the density of the γ' phase,a synergistic increase in strength and degradation rate can be achieved.On the one hand,the increase in corrosion rate was related to the increased volume fraction of the bulk LPSO phase and the densities of the lamellar γ' phase,which provide more galvanic corrosion.Moreover,high densities of the lamellar γ' phase can provide more corrosion interface by inhibiting the recrystallization process to refine dynamic recrystallized(DRXed)grains during the hot extrusion.On the other hand,the ultimate tensile strength(UTS)and tensile yield strength(TYS)of the Mg-Er-Ni alloy increased from 345 and 265 MPa to 514 MPa and 358 MPa,respectively,which was mainly attributed to grain boundary and texture strengthening,bulk LPSO phase and lamellar γ' phase strengthening.Overall,Mg^(-1)4Er-4Ni alloy,which contains the highest volume fraction bulk LPSO phase and the densities of lamellar γ' phase,re-alized a synergistic enhancement of strength and degradation rate.The UTS,TYS,and degradation rate of Mg^(-1)4Er-4Ni were 514 MPa,358 MPa,and 142.5 mg cm^(-2)h^(-1)(3 wt%KCl solution at 93◦C),respectively.This research provides new insight into developing Mg alloys with high strength and degradation rates for fracturing tool materials in the application of oil and gas exploitation in harsh environments. 展开更多
关键词 Mg-Er-Ni alloy Lamellarγ'and bulk LPSO phases Rapid degradation rate High strength Mechanical and corrosion mechanism
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基于英语学科的高中生文化理解力的内涵、价值与培养策略
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作者 高琦悦 刘鹂 《课程.教材.教法》 北大核心 2023年第10期105-110,共6页
基于英语学科的高中生文化理解力指的是高中生对英语学科所蕴含的中外文化的理解能力,其价值体现在助力高中生英语听、说、读、看、写语言技能的提升,加强高中生对中华优秀文化的认同和传承,促进高中生的跨文化交际与传播。为培养基于... 基于英语学科的高中生文化理解力指的是高中生对英语学科所蕴含的中外文化的理解能力,其价值体现在助力高中生英语听、说、读、看、写语言技能的提升,加强高中生对中华优秀文化的认同和传承,促进高中生的跨文化交际与传播。为培养基于英语学科的高中生文化理解力,教师要扩充学生中外文化知识,奠定文化理解基础;研读英语教材语篇,深挖语篇文化内容;依托单元文化主题,开展项目化学习;组织丰富的文化活动,增强学生文化体验。 展开更多
关键词 高中英语 文化理解力 核心素养
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乡村振兴背景下定西市安定区马铃薯产业链优化提升策略研究 被引量:2
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作者 党一 《智慧农业导刊》 2023年第4期68-71,75,共5页
马铃薯产业作为定西市安定区优势特色产业,在增加群众收入、打赢脱贫攻坚战、推进区域经济社会发展中起到重要作用。乡村振兴战略提出产业兴旺要求,要实现马铃薯产业兴旺,必须优化提升马铃薯产业链。一要构建“企业+合作社+村集体+农户... 马铃薯产业作为定西市安定区优势特色产业,在增加群众收入、打赢脱贫攻坚战、推进区域经济社会发展中起到重要作用。乡村振兴战略提出产业兴旺要求,要实现马铃薯产业兴旺,必须优化提升马铃薯产业链。一要构建“企业+合作社+村集体+农户”种植模式,优化提升生产链;二要构建马铃薯系列产品加工车间,优化提升加工链;三要构建“线上+线下”销售模式,优化提升营销链;四要构建覆盖村社的物流服务体系,优化提升流通链;五要构建“产业+文旅”融合发展模式,优化提升体验链;六要构建党委政府推动保障机制,优化提升保障链。 展开更多
关键词 安定区 马铃薯产业链 优化提升 对策 乡村振兴
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农膜回收利用防治农膜残留污染的研究 被引量:1
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作者 张喜龙 《农业技术与装备》 2023年第11期112-114,共3页
现代农业生产中,覆膜栽培技术得到广泛应用,使用覆膜栽培不仅能够提高地温、保持土壤湿度、促进种子发芽,还能抑制杂草生长,利于农作物生长,但也带来了农业面源的污染。以定西市安定区为例,概述了农膜回收利用的意义,分析了农膜回收利... 现代农业生产中,覆膜栽培技术得到广泛应用,使用覆膜栽培不仅能够提高地温、保持土壤湿度、促进种子发芽,还能抑制杂草生长,利于农作物生长,但也带来了农业面源的污染。以定西市安定区为例,概述了农膜回收利用的意义,分析了农膜回收利用现状与问题,探讨了加快推进农膜回收利用、防治农膜残留污染的策略。 展开更多
关键词 农膜 回收 利用 安定区
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西汉安定郡彭阳、安定、抚夷三县治所考
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作者 王博文 《文博》 北大核心 2023年第1期66-70,共5页
本文依据文献及考古资料,重新探讨了西汉安定郡彭阳、安定、抚夷县治的具体位置,认为彭阳县治在今甘肃省镇原县太平镇茹河北岸的阳湾遗址,抚夷县治在今三岔镇蒲河北岸的梁台遗址。笔者认同《中国历史地图集》关于彭阳、抚夷两县治所方... 本文依据文献及考古资料,重新探讨了西汉安定郡彭阳、安定、抚夷县治的具体位置,认为彭阳县治在今甘肃省镇原县太平镇茹河北岸的阳湾遗址,抚夷县治在今三岔镇蒲河北岸的梁台遗址。笔者认同《中国历史地图集》关于彭阳、抚夷两县治所方位的标注,并为之提供了新的考古资料进行佐证,且进一步确认其位置。本文对标注在今泾川县的安定县重新进行了考证,认为县治在今镇原县东南10千米处城关镇茹河北岸的后河遗址。 展开更多
关键词 西汉 彭阳 安定 抚夷 县治
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