期刊文献+
共找到22篇文章
< 1 2 >
每页显示 20 50 100
Deterministic processes drive turnover-dominated beta diversity of breeding birds along the central Himalayan elevation gradient
1
作者 zhifeng ding Jianchao Liang +3 位作者 Le Yang Cong Wei Huijian Hu Xingfeng Si 《Avian Research》 SCIE CSCD 2024年第2期163-171,共9页
Beta diversity,the variation of community composition among sites,bridges alpha and gamma diversity and can reveal the mechanisms of community assembly through applying distance-decay models and/or partitioning beta d... Beta diversity,the variation of community composition among sites,bridges alpha and gamma diversity and can reveal the mechanisms of community assembly through applying distance-decay models and/or partitioning beta diversity into turnover and nestedness components from functional and phylogenetic perspectives.Mountains as the most natural experiment system provide good opportunities for exploring beta diversity patterns and the underlying ecological processes.Here,we simultaneously consider distance-decay models and multiple di-mensions of beta diversity to examine spatial variations of bird communities,and to evaluate the relative importance of niche-based and neutral community assembly mechanisms along a 3600-m elevational gradient in the central Himalayas,China.Our results showed that species turnover dominates taxonomic,functional,and phylogenetic beta diversity.We observed strongest evidence of spatial distance decays in taxonomic similarities of birds,followed by its phylogenetic and functional analogues.Turnover component was highest in taxonomic beta diversity,while nestedness component was highest in functional beta diversity.Further,all correlations of assemblage similarity with climatic distance were higher than that with spatial distances.Standardized values of overall taxonomic,functional,and phylogenetic beta diversity and their turnover components increase with increasing elevational distance,while the standardized values of taxonomic and phylogenetic nestedness decreased with increasing elevational distance.Our results highlighted the niche-based deterministic processes in shaping elevational bird diversity patterns that were determined by the relative roles of decreasing trend of environmental filtering and increasing trend of limiting similarity along elevation distances. 展开更多
关键词 Beta diversity BIRD Community assembly Functional trait HIMALAYA Nestedenss Phylogenetic distance TURNOVER
下载PDF
Upper-mantle velocity structures beneath the Tibetan Plateau and surrounding areas inferred from triplicated P waveforms 被引量:9
2
作者 RiSheng Chu LuPei Zhu zhifeng ding 《Earth and Planetary Physics》 CSCD 2019年第5期444-458,共15页
P-wave waveforms in the distance range between 12°and 30°were analyzed to investigate upper-mantle P velocity structures beneath the Tibetan Plateau and surrounding areas.The waveform data from 504 earthquak... P-wave waveforms in the distance range between 12°and 30°were analyzed to investigate upper-mantle P velocity structures beneath the Tibetan Plateau and surrounding areas.The waveform data from 504 earthquakes with magnitudes larger than 5.0 between 1990 and 2005 that occurred within 30°from the center of the Plateau were modelled.We divided the study area into 6 regions and modeled upper-mantle-distance P waveforms with turning points beneath each region separately.The results show that the uppermantle P-wave velocity structures beneath India,the Himalayas,and the Lhasa Terrane are similar and contain a high-velocity lid about 250 km thick.The upper-mantle velocities down to 200 km beneath the Qiangtang Terrane,the Tarim Basin,and especially the Songpan-GarzêTerrane are lower than those in the south.The 410-km discontinuity beneath these two terranes is elevated by about 20 km.Highvelocity anomalies are found in the transition zone below 500 km under the Lhasa and Qiangtang Terranes.The results suggest that the Tibetan Plateau was generated by thrusting of the Indian mantle lithosphere under the southern part of Tibet.Portions of the thickened Eurasian mantle lithosphere were delaminated;they are now sitting in the transition zone beneath southern Tibet and atop of the 410-km discontinuity underneath northern Tibet. 展开更多
关键词 TIBETAN Plateau upper MANTLE structure triplication waveform modelling
下载PDF
Joint inversion of Rayleigh group and phase velocities for S-wave velocity structure of the 2021 M_(S)6.0 Luxian earthquake source area,China
3
作者 Wei Xu Pingping Wu +4 位作者 Dahu Li Huili Guo Qiyan Yang Laiyu Lu zhifeng ding 《Earthquake Science》 2023年第5期356-375,共20页
On September 16,2021,a MS6.0 earthquake struck Luxian County,one of the shale gas blocks in the Southeastern Sichuan Basin,China.To understand the seismogenic environment and its mechanism,we inverted a fine three-dim... On September 16,2021,a MS6.0 earthquake struck Luxian County,one of the shale gas blocks in the Southeastern Sichuan Basin,China.To understand the seismogenic environment and its mechanism,we inverted a fine three-dimensional S-wave velocity model from ambient noise tomography using data from a newly deployed dense seismic array around the epicenter,by extracting and jointly inverting the Rayleigh phase and group velocities in the period of 1.6–7.2 s.The results showed that the velocity model varied significantly beneath different geological units.The Yujiasi syncline is characterized by low velocity at depths of~3.0–4.0 km,corresponding to the stable sedimentary layer in the Sichuan Basin.The eastern and western branches of the Huayingshan fault belt generally exhibit high velocities in the NE-SW direction,with a few local low-velocity zones.The Luxian MS6.0 earthquake epicenter is located at the boundary between the high-and low-velocity zones,and the earthquake sequences expand eastward from the epicenter at depths of 3.0–5.0 km.Integrated with the velocity variations around the epicenter,distribution of aftershock sequences,and focal mechanism solution,it is speculated that the seismogenic mechanism of the main shock might be interpreted as the reactivation of pre-existing faults by hydraulic fracturing. 展开更多
关键词 Luxian earthquake ambient noise tomography S-wave velocity model SEISMICITY seismogenic mechanism joint inversion
下载PDF
Crustal stress field in Yunnan: implication for crust-mantle coupling 被引量:24
4
作者 Zhigang Xu Zhouchuan Huang +6 位作者 Liangshu Wang Mingjie Xu zhifeng ding Pan Wang Ning Mi Dayong Yu Hua Li 《Earthquake Science》 CSCD 2016年第2期105-115,共11页
We applied the g CAP algorithm to determine 239 focal mechanism solutions 3:0≤MW≤ 6:0) with records of dense Chin Array stations deployed in Yunnan,and then inverted 686 focal mechanisms(including 447 previous r... We applied the g CAP algorithm to determine 239 focal mechanism solutions 3:0≤MW≤ 6:0) with records of dense Chin Array stations deployed in Yunnan,and then inverted 686 focal mechanisms(including 447 previous results) for the regional crustal stress field with a damped linear inversion. The results indicate dominantly strike-slip environment in Yunnan as both the maximum(r1) and minimum(r3) principal stress axes are sub-horizontal. We further calculated the horizontal stress orientations(i.e., maximum and minimum horizontal compressive stress axes: S H and S h, respectively) accordingly and found an abrupt change near *26°N. To the north, S H aligns NW-SE to nearly E-W while S h aligns nearly N-S. In contrast, to the south, both S H and S h rotate laterally and show dominantly fan-shaped patterns. The minimum horizontal stress(i.e., maximum strain axis) S h rotates from NW-SE to the west of Tengchong volcano gradually to nearly E-W in west Yunnan, and further toNE-SW in the South China block in the east. The crustal strain field is consistent with the upper mantle strain field indicated by shear-wave splitting observations in Yunnan but not in other regions. Therefore, the crust and upper mantle in Yunnan are coupled and suffering vertically coherent pure-shear deformation in the lithosphere. 展开更多
关键词 TIBET YUNNAN Focal mechanism solution Stress field Crust-mantle coupling
下载PDF
Crustal and uppermost mantle structure of SE Tibetan plateau from Rayleigh-wave group-velocity measurements 被引量:23
5
作者 Yonghua Li Jiatie Pan +1 位作者 Qingju Wu zhifeng ding 《Earthquake Science》 2014年第4期411-419,共9页
A shear-wave velocity model of the crust and uppermost mantle beneath the SE Tibetan plateau was derived by inverting Rayleigh-wave group-velocity mea- surements of periods between 10 and 70 s. Rayleigh-wave group-vel... A shear-wave velocity model of the crust and uppermost mantle beneath the SE Tibetan plateau was derived by inverting Rayleigh-wave group-velocity mea- surements of periods between 10 and 70 s. Rayleigh-wave group-velocity dispersions along more than 3,000 inter- station paths were measured based on analysis of telese- ismic wavelbrm data recorded by temporary seismic stations. These observations were then utilized to construct 2D group-velocity maps in the period range of 10-70 s. Tile new group-velocity maps have an enhanced resolution compared with previous global and regional group-velocity models in this region because of the denser and more uniform data coverage. The lateral resolution across the region is about 0.5° for the periods used in this study. Local dispersion curves were then inverted for a 3D shear-wave velocity model of the region by applying a linear inversion scheme. Our 3D shear-wave model confirms the presence of low-velocity zones (LVZs) in the crust beneath the northern part of this region. Our irnaging shows that the upper-middle crustal LVZ beneath the Tengchong region is isolated from these LVZs beneath the eastern and northern part of this region. The upper-middle crustal LVZ may be regarded as evidence of a rnagma chamber in the crust beneath the Tengchong Volcanoes. Our model also reveals a slow lithospheric structure beneath Tengchong and a fast shield-like mantle beneath the stable Yangtze block. 展开更多
关键词 SE Tibetan plateau Shear-wave velocity Rayleigh-wave tomography Group velocity
下载PDF
Crustal velocity structures beneath North China revealed by ambient noise tomography 被引量:7
6
作者 Lihua Fang Jianping Wu +2 位作者 zhifeng ding Weilai Wang Giuliano Francesco Panza 《Earthquake Science》 CSCD 2010年第5期477-486,共10页
We collected continuous noise waveform data from January 2007 to February 2008 recorded by 190 broadband and 10 very broadband stations of the North China Seismic Array. The study region is divided into grid with inte... We collected continuous noise waveform data from January 2007 to February 2008 recorded by 190 broadband and 10 very broadband stations of the North China Seismic Array. The study region is divided into grid with interval 0.25°×0.25°, and group velocity distribution maps between 4 s and 30 s are obtained using ambient noise tomography method. The lateral resolution is estimated to be 20-50 km for most of the study area. We construct a 3-D S wave velocity model by inverting the pure path dispersion curve at each grid using a genetic algorithm with smoothing constraint. The crustal structure observed in the model includes sedimentary basins such as North China basin, Yanqing-Huailai basin and Datong basin. A well-defined low velocity zone is observed in the Beijing-Tianjin-Tangshan region in 22-30 km depth range, which may be related to the upwelling of hot mantle material. The high velocity zone near Datong, Shuozhou and Qingshuihe within the depth range of 1-23 km reveals stable characteristics of Ordos block. The Taihangshan front fault extends to 12 km depth at least. 展开更多
关键词 seismic noise surface wave tomography velocity structure genetic algorithm North China
下载PDF
Upper crustal velocity and seismogenic environment of the M7.0 Jiuzhaigou earthquake region in Sichuan, China 被引量:9
7
作者 DaHu Li zhifeng ding +3 位作者 Yan Zhan PingPing Wu LiJun Chang XiangYu Sun 《Earth and Planetary Physics》 CSCD 2021年第4期348-361,共14页
On August 8,2017,a magnitude 7.0 earthquake occurred in Jiuzhaigou County,Sichuan Province,China.The deep seismogenic environment and potential seismic risk in the eastern margin of Tibetan Plateau have once again att... On August 8,2017,a magnitude 7.0 earthquake occurred in Jiuzhaigou County,Sichuan Province,China.The deep seismogenic environment and potential seismic risk in the eastern margin of Tibetan Plateau have once again attracted the close attention of seismologists and scholars at home and abroad.The post-earthquake scientific investigation could not identify noticeable surface rupture zones in the affected area;the complex tectonic background and the reason(s)for the frequent seismicity in the Jiuzhaigou earthquake region are unclear.In order to reveal the characteristics of the deep medium and the seismogenic environment of the M7.0 Jiuzhaigou earthquake region,and to interpret the tectonic background and genesis of the seismicity comprehensively,in this paper,we have reviewed all available observation data recorded by the regional digital seismic networks and large-scale,dense mobile seismic array(China Array)for the northern section of the North-South Seismic Belt around Jiuzhaigou earthquake region.Using double-difference seismic tomography method to invert the three-dimensional P-wave velocity structure characteristics of the upper crust around the Jiuzhaigou earthquake region,we have analyzed and discussed such scientific questions as the relationship between the velocity structure characteristics and seismicity in the Jiuzhaigou earthquake region,its deep tectonic environment,and the ongoing seismic risk in this region.We report that:the P-wave velocity structure of the upper crust around the Jiuzhaigoug earthquake region exhibits obvious lateral inhomogeneity;the distribution characteristics of the shallow P-wave velocity structure are closely related to surface geological structure and formation lithology;the M7.0 Jiuzhaigou earthquake sequence is closely related to the velocity structure of the upper crust;the mainshock of the M7.0 earthquake occurred in the upper crust;the inhomogeneous variation of the velocity structure of the Jiuzhaigou earthquake area and its surrounding medium appears to be the deep structural factor controlling the spatial distribution of the mainshock and its sequence.The 3D P-wave velocity structure also suggests that the crustal low-velocity layer of northeastern SGB(Songpan-GarzêBlock)stretches into MSM(Minshan Mountain),and migrates to the northeast,but the tendency to emerge as a shallow layer is impeded by the high-velocity zone of Nanping Nappe tectonics and the Bikou Block.Our results reveal an uneven distribution of high-and low-velocity structures around the Tazang segment of the East Kunlun fault zone.Given that the rupture caused by the Jiuzhaigou earthquake has enhanced the stress fields at both ends of the seismogenic fault,it is very important to stay vigilant to possible seismic hazards in the large seismic gap at the Maqu-Maqên segment of the East Kunlun fault zone. 展开更多
关键词 the M7.0 Jiuzhaigou earthquake 3D P-wave velocity structure deep tectonic seismogenic environment
下载PDF
Upper crustal anisotropy observed around the Longmenshan fault in the 2013 M_S7.0 Lushan earthquake region 被引量:3
8
作者 Lijun Chang zhifeng ding Chunyong Wang 《Earthquake Science》 CSCD 2018年第4期187-198,共12页
Based on the shear wave splitting analysis of the seismic recordings at 17 temporary stations and three permanent stations, we measured the shear wave splitting parameters(i.e., the polarization direction of fast shea... Based on the shear wave splitting analysis of the seismic recordings at 17 temporary stations and three permanent stations, we measured the shear wave splitting parameters(i.e., the polarization direction of fast shear wave and the time delay of slow wave) to perform a systematic analysis of the crustal seismic anisotropy around the Longmenshan fault in the 2013 M7.0 Lushan earthquake region. We observed apparent spatio-temporal characteristics in the shear wave splitting parameters. The spatial distribution of fast polarization directions showed a clear partitioning in the characteristics from northwest to southeast in the focal region,which changed from NW-SE to NE-SW. In the northwest of the focal region, the fast polarization direction was oriented to NW-SE, which was parallel to the maximum horizontal compressive stress direction. However, the NE-SW fast polarization direction in the southeast of the focal region was parallel to the Longmenshan fault strike. For station BAX on the Central fault in the middle of the focal region, the distribution of fast polarization directions showed a bimodal pattern, with one dominant in the NE-SW direction and the other in the NW-SE direction. With regard to the temporal variation, the time delays were large in the initial stage after the mainshock but then gradually decreased over time and tended to be stable in the later period. This indicated that stress in the focal region increased to a maximum when the main shock occurred, with the stress release caused by the mainshock and aftershock activity, and the stress gradually decreased after a period of time. The scatter of fast polarization directions was large after the main shock, but over time the scatter gradually decreased, indicating that the Lushan earthquake caused a large perturbation in the local stress field. As the stress gradually decreased and was adjusted by the aftershock activity, the perturbation gradually weakened. 展开更多
关键词 Lushan earthquake crustal anisotropy crustal stress fast polarization direction time delay
下载PDF
Effect of uneven noise source and/or station distribution on estimating the azimuth anisotropy of surface waves 被引量:2
9
作者 Laiyu Lu Kaiming Wang zhifeng ding 《Earthquake Science》 CSCD 2018年第4期175-186,共12页
With the development of the dense array,the surface wave velocity and azimuthal anisotropy under the array can be directly obtained by beamforming the noise cross-correlation functions(NCFs). However, the retrieval of... With the development of the dense array,the surface wave velocity and azimuthal anisotropy under the array can be directly obtained by beamforming the noise cross-correlation functions(NCFs). However, the retrieval of the Green’s function by cross-correlating the seismic noise requires that the noise source has a uniform distribution. For the case with uneven noise source, the azimuthal dependence on the sources in the expression for the spatial coherence function, which corresponds to the NCF in the time domain,has the same form as the azimuthal dependence of the surface wave velocity in weakly anisotropic media. Therefore, the uneven noise source will affect the surface wave anisotropy extraction. In this study, three passive seismic methods, i.e.,beamforming, SPAC(spatial autocorrelation), and NCF, are compared to demonstrate that an uneven source distribution and uneven station distribution have equivalent effects on the outcome from each method. A beamforming method is proposed to directly extract the velocity and azimuthal anisotropy of surface waves. The effect of uneven noise source and/or station distribution on estimating the azimuth anisotropy of surface waves was investigated using data from the ChinArray Phase Ⅱ. A method for correcting the apparent anisotropy in beamforming results caused by an uneven station distribution is suggested. 展开更多
关键词 BEAMFORMING uneven seismic noise source uneven station distribution azimuthal anisotropy
下载PDF
Brood sex ratio in the Yellow-bellied Prinia(Prinia flaviventris) 被引量:2
10
作者 zhifeng ding Fang Ji +7 位作者 Qiuli Huang Longwu Wang Aiwu Jiang Chunlan Zhang Yongjun Feng Yuan Tian Huijian Hu Wei Liang 《Avian Research》 CSCD 2017年第2期76-82,共7页
Background:The adjustment of sex ratios in birds can occur at the egg and nestling stages. Previous studies showed that the sex ratio was affected by environmental factors and parental condition; it may result in seas... Background:The adjustment of sex ratios in birds can occur at the egg and nestling stages. Previous studies showed that the sex ratio was affected by environmental factors and parental condition; it may result in seasonal and ecosystem differences.Methods:In this study, the brood sex ratio of the Yellow-bellied Prinia(Prinia flaviventris) in the Nonggang area, Guangxi, southwestern China, was investigated during the breeding season from May to June in 2013 using PCR amplification from whole-genome DNA extracted from blood samples. A total of 31 nests of Yellow-bellied Prinia, including 132 brood fledglings and 31 pairs, were sampled.Results:The results showed that the brood sex ratio of the Yellow-bellied Prinia was 1:1, and sex ratios of different nests were evenly distributed within the study area. No significant relationship was found between parental quality and nest characteristics with the brood sex ratio.Conclusions:The present study indicated that no brood sex ratio bias in the Yellow-bellied Prinia highlighted the complexity of sex ratio adjustment in birds. In spite of our negative results, the lack of an association between brood sex ratio and parental quality and environmental factors in the Yellow-bellied Prinia provides valuable information on the adjustment of sex ratios in birds. 展开更多
关键词 Brood sex ratio Parental quality Yellow-bellied Prinia Prinia flaviventris Sex ratio adjustment
下载PDF
Preface to the special issue China Seismic Experimental Site(CSES):on-going progresses and future prospects 被引量:2
11
作者 Zhongliang Wu zhifeng ding 《Earthquake Science》 2021年第3期189-191,共3页
In 2018,the International Conference for the Decade Memory of the Wenchuan Earthquake in connection to the 4th International Conference on Continental Earthquakes(4th ICCE)and the 12th Assembly of Asian Seismological ... In 2018,the International Conference for the Decade Memory of the Wenchuan Earthquake in connection to the 4th International Conference on Continental Earthquakes(4th ICCE)and the 12th Assembly of Asian Seismological Commission(ASC)officially announced the establishment of China Seismic Experimental Site(CSES)in the Sichuan-Yunnan region.CSES focuses on the field experiments on a broad spectra of scientific problems in earthquake science,from the tectonics and physics of earthquakes and faulting to the engineering countermeasures for disaster risk reduction.In spring of 2021,approved by the Standing Committee of the National People's Congress of China,CSES as a key state scientific infrastructure was enlisted in the 14th national five-year plan(2021–2025)of economic and social development and the long-term vision of 2035,which is considered as a major step for promoting earthquake science in China.Since 2018,the planning,construction and functioning of CSES have attracted much attention in earthquake science(CSES,2020a,b,c;Wu ZL et al.,2021a,b,c,d).This special issue of Earthquake Science,similar to other publications(e.g.,Li YG et al.,2021),reflects a profile of the on-going works of CSES,by CSES,and for CSES.Totally 8 articles are included in the present issue,covering some aspects of research scopes of CSES. 展开更多
关键词 China SEISMIC EARTHQUAKE
下载PDF
Bird guild loss and its determinants on subtropical land-bridge islands, China 被引量:1
12
作者 zhifeng ding Kenneth James Feeley +1 位作者 Huijian Hu Ping ding 《Chinese Birds》 CSCD 2015年第2期99-106,共8页
Background: The guild concept is useful for understanding the community structure in a land-bridge island system,but most fragmentation studies have focused only on the importance of island area and isolation, other i... Background: The guild concept is useful for understanding the community structure in a land-bridge island system,but most fragmentation studies have focused only on the importance of island area and isolation, other island attributes such as perimeter-area ratio(PAR) were overlooked or understudied.Methods: We have adopted a guild approach to investigate the impacts of island attributes on bird guild richness on a set of 41 recently isolated land-bridge islands in the Thousand Island Lake(TIL), China.Results: We found insectivores had the largest number of species(34 species), fol owed by understory foraging guilds(28 species), omnivores(27 species) and canopy guilds(25 species). Furthermore, our data showed that migrants and residents responded equal y to island area, insectivores and understory guilds were sensitive to island area but omnivores and canopy guilds were not very sensitive. Most guild richness was determined by island area, except for omnivores and canopy guilds.Conclusions: Although PAR or habitat diversity found to be important for bird species richness, our results highlight the importance of island area in maintaining bird diversity in fragmented island systems. 展开更多
关键词 BIRD GUILDS ISLAND area Land-bridge islands PAR Thousand ISLAND Lake z values
下载PDF
通过接收函数和瑞利波联合反演揭示青藏高原东南缘两个壳内低速通道
13
作者 Xuewei Bao Xiaoxiao Sun +13 位作者 Mingjie Xu David W.Eaton Xiaodong Song Liangshu Wang zhifeng ding Ning Mi Hua Li Dayong Yu Zhouchuan Huang Pan Wang 孙晓晓(译) 鲍学伟(译) 徐鸣洁(校) 朱玉萍(复校) 《世界地震译丛》 2016年第4期329-343,共15页
目前解释青藏高原东缘的生长与扩张有诸多动力学模型,如:刚性块体挤出模型、连续变形和中下地壳流模型。由于受到岩石层结构模型分辨率的限制,青藏高原演化和变形的动力学过程仍不清楚。我们利用最新布设在青藏高原东南缘的地震台阵,通... 目前解释青藏高原东缘的生长与扩张有诸多动力学模型,如:刚性块体挤出模型、连续变形和中下地壳流模型。由于受到岩石层结构模型分辨率的限制,青藏高原演化和变形的动力学过程仍不清楚。我们利用最新布设在青藏高原东南缘的地震台阵,通过接收函数和瑞利波联合反演得到了该区高分辨率三维岩石层横波速度模型,更好地揭示了壳内低速带(LVZ)分布特征。我们的速度模型显示研究区壳内存在两个低速通道,这两个低速通道边界与该区主要走滑断裂相对应,且沿着东喜马拉雅构造结顺时针分布,这与该区地壳物质顺时针运动模式比较一致。此外,我们观测到该区域主要大地震分布在这两个低速通道边界区域。据此,我们提出塑性流动和剪切变形在青藏高原的隆升和变形过程中都起了重要作用。 展开更多
关键词 青藏高原 低速带 地壳流 瑞利波 接收函数 联合反演
下载PDF
青藏高原东南缘远震S波分裂:对地壳上地幔复杂变形的启示
14
作者 zhouchuan huang liangshu wang +10 位作者 mingjie xu zhifeng ding yan wu pan wang ning mi dayong yu hua li 曹旭(译) 韩青(译) 黄周传(校) 吴何珍(复校) 《世界地震译丛》 2016年第5期443-456,共14页
利用位于青藏高原东南缘云南地区的中国地震科学探测台站(C h in A ra y )一期3 0 0 多个宽频带流动台站记录到的X K S 波形(包括SKS,S K K S, PKS)进行了 S 波分裂分析.X K S 分裂结果最主要的特征是快波偏振方向(φ) 在26-27&... 利用位于青藏高原东南缘云南地区的中国地震科学探测台站(C h in A ra y )一期3 0 0 多个宽频带流动台站记录到的X K S 波形(包括SKS,S K K S, PKS)进行了 S 波分裂分析.X K S 分裂结果最主要的特征是快波偏振方向(φ) 在26-27°N 附近,从北部的近N -S 向突变为南部的近E-W 向.研究区西部喜马拉雅东构造结附近的结果较好地反映了岩石层左旋剪切变形下发育的各向异性.26°N 以南地区,快波分裂方向以E-W 向为主,与中上地壳最大张应力的方向一致,表明云南地区整个岩石层都可能处于纯剪切变形环境.但是该区岩石层厚度不足80k m ,产生的X K S 分裂快慢波时差(〈0.7s)仅能解释部分观测值(0.9-1.5s) .因此,软流层中的各向异性对于该地区的S 波分裂结果(快波偏振方向为N W -S E 和近E-W 向)可能产生了重要的作用.一方面,N W - S E 向快波偏振方向可能反映了缅甸块体的俯冲及其随后撤退引起的上地幔流动造成的各向异性.另一方面,伴随着高原构造演化发生的从青藏高原向中国东部的软流层物质流动,以及由于绝对板块运动造成的软流层顶部的剪切作用,将产生快波方向为近E-W 向的各向异性.本研究结果为研究青藏高原东南缘不同深度的变形特征及其差异提供了重要的信息,尤其在研究青藏高原的构造抬升及其向东南缘的扩展方面产生了新的认识. 展开更多
关键词 滇藏 中国地震科学探测台站 S波分裂 地震各向异性 岩石层耦合 软流层流动
下载PDF
基于全球定位系统、第四纪断层滑动速率和横波分裂测量数据分析喜马拉雅东构造结岩石层垂直连贯变形
15
作者 lijun chang lucy m.flesch +3 位作者 chun-yung wang zhifeng ding 常利军(译) 朱玉萍(校) 《世界地震译丛》 2016年第3期234-242,共9页
测量了喜马拉雅东构造结59个新的地震台站的SKS/SKKS波分裂参数,并结合前人在该区域得到的69个台站的横波分裂结果,以此来分析东构造结的地幔变形场特征。密集各向异性测量结果显示,快波方向在东构造结核心部位的南迦巴瓦为NE—SW方向,... 测量了喜马拉雅东构造结59个新的地震台站的SKS/SKKS波分裂参数,并结合前人在该区域得到的69个台站的横波分裂结果,以此来分析东构造结的地幔变形场特征。密集各向异性测量结果显示,快波方向在东构造结核心部位的南迦巴瓦为NE—SW方向,其周边地区为绕南迦巴瓦顺时针旋转的特征。我们基于全球定位系统(GPS)和第四纪断层滑动速率测量数据确定了一个连续的地表变形场,并以此来模拟每个台站预测的快波方向。通过快波方向的测量值和预测值对比分析,南迦巴瓦11个台站快波方向的测量值和预测值的平均角度差达60.8°,而其周边地区的角度差只有11.7°,这说明除南迦巴瓦以外,东构造结岩石层变形特征主要为垂直连贯变形模式,而南迦巴瓦不符合垂直连贯变形模式。地幔各向异性的复杂性和地表观察表明南迦巴瓦应变场的局部变形岩石层可能与印度板块在其下方俯冲作用有关。 展开更多
关键词 全球定位系统 断层滑动速率 测量数据 喜马拉雅 横波分裂 构造结 岩石层 变形场
下载PDF
Modeling the effects of extreme high-temperature stress at anthesis and grain filling on grain protein in winter wheat
16
作者 Raheel Osman Yan Zhu +5 位作者 Weixing Cao zhifeng ding Meng Wang Leilei Liu Liang Tang Bing Liu 《The Crop Journal》 SCIE CSCD 2021年第4期889-900,共12页
Extreme high-temperature stress(HTS) associated with climate change poses potential threats to wheat grain yield and quality. Wheat grain protein concentration(GPC) is a determinant of wheat quality for human nutritio... Extreme high-temperature stress(HTS) associated with climate change poses potential threats to wheat grain yield and quality. Wheat grain protein concentration(GPC) is a determinant of wheat quality for human nutrition and is often neglected in attempts to assess climate change impacts on wheat production. Crop models are useful tools for quantification of temperature impacts on grain yield and quality.Current crop models either cannot simulate or can simulate only partially the effects of HTS on crop N dynamics and grain N accumulation. There is a paucity of observational data on crop N and grain quality collected under systematic HTS scenarios to develop algorithms for model improvement as well as evaluate crop models. Two-year phytotron experiments were conducted with two wheat cultivars under HTS at anthesis, grain filling, and both stages. HTS significantly reduced total aboveground N and increased the rate of grain N accumulation, while total aboveground N and the rate of grain N accumulation were more sensitive to HTS at anthesis than at grain filling. The observed relationships between total aboveground N, rate of grain N accumulation, and HTS were quantified and incorporated into the WheatGrow model. The new HTS routines improved simulation of the dynamics of total aboveground N, grain N accumulation, and GPC by the model. The improved model provided better estimates of total aboveground N, grain N accumulation, and GPC under HTS(the normalized root mean square error was reduced by 40%, 85%, and 80%, respectively) than the original WheatGrow model. The improvements in the model enhance its applicability to the assessment of climate change effects on wheat grain quality by reducing the uncertainties of simulating N dynamics and grain quality under HTS. 展开更多
关键词 Heat stress Total aboveground N Grain N accumulation Grain protein concentration Model improvement WheatGrow model
下载PDF
粤港澳大湾区城市化进程对区域内鸟类分布及栖息地连通性的影响 被引量:6
17
作者 张琼悦 邓卓迪 +9 位作者 胡学斌 丁志锋 肖荣波 修晨 吴政浩 汪光 韩东晖 张语克 梁健超 胡慧建 《生物多样性》 CAS CSCD 北大核心 2023年第3期68-80,共13页
粤港澳大湾区经济快速发展和城市迅速扩张引起土地利用类型的剧烈转变,这对当地物种的栖息地、物种分布区乃至区域生物多样性均造成了影响。本研究基于82种鸟类的分布数据和15个环境变量数据,利用最大熵(maximumentropy,MaxEnt)模型及... 粤港澳大湾区经济快速发展和城市迅速扩张引起土地利用类型的剧烈转变,这对当地物种的栖息地、物种分布区乃至区域生物多样性均造成了影响。本研究基于82种鸟类的分布数据和15个环境变量数据,利用最大熵(maximumentropy,MaxEnt)模型及等效连接面积(the equivalent connected area,ECA)指数分析了粤港澳大湾区鸟类多样性的空间分布格局及连通性。结果表明:2000-2015年,大湾区林地、水体、耕地等用地类型分别减少3.22%、0.97%和23.19%,草地、建设用地、裸地与滩涂用地类型分别增加33.95%、80.34%和453.52%。30种以森林、农田为主要栖息生境的鸟类分布区面积减少,52种常见的城市鸟类及各类水鸟分布面积增加,鸟类分布面积与土地利用类型密切相关。此外,鸟类栖息地连接度表现出与分布区相一致的变化趋势。其中,对4种分布面积变化最大的鸟类的分析结果显示,乌鹃(Surniculuslugubris)与栗耳凤鹛(Yuhina castaniceps)分布面积及栖息地连通性随城市化进程(包括土地利用类型、植被覆盖度、水源距离和干扰距离等的变化)而下降,而牛背鹭(Bubulcus ibis)与苍鹭(Ardea cinerea)的分布面积及栖息地连通性则随城市化进程而上升。此外栖息地斑块面积的增加也显著提高了栖息地的连通性。因此建议对城市化进程中粤港澳大湾区的生境质量变化进行评估,根据评估结果构建鸟类生态廊道和生物多样性保护网络,从而维持大湾区区域生态系统的安全和稳定。 展开更多
关键词 连通性 MaxEnt模型 鸟类分布 栖息地斑块 土地利用变化 粤港澳大湾区
原文传递
中国陆生脊椎动物野外调查的发展现状与文献分析 被引量:5
18
作者 吴政浩 丁志锋 +5 位作者 周智鑫 梁健超 王卓婷 章亚宁 胡一鸣 胡慧建 《生物多样性》 CAS CSCD 北大核心 2023年第3期198-215,共18页
新中国成立以来,我国已开展了大量陆生脊椎动物的本底调查和多样性研究项目,取得了一系列成果,并有学者针对兽类、鸟类和两栖爬行类的野外调查监测进行了总结和展望,但尚缺乏对所有陆生脊椎动物类群的调查历史和现状的分析及基于文献收... 新中国成立以来,我国已开展了大量陆生脊椎动物的本底调查和多样性研究项目,取得了一系列成果,并有学者针对兽类、鸟类和两栖爬行类的野外调查监测进行了总结和展望,但尚缺乏对所有陆生脊椎动物类群的调查历史和现状的分析及基于文献收集的研究,特别是对调查方法和技术手段的对比与总结。因此,本文通过文献收集的方法,基于中国知网、Web of Science核心合集和以图书检索为主的读秀学术搜索,以“兽类”“鸟类”“爬行类”“两栖类”“动物资源”“调查”“监测”“新种”“新记录”和“物种多样性”作为检索词,检索并筛选了与兽类、鸟类、爬行类及两栖类陆生脊椎动物调查相关的文献资料共3,504篇,对陆生脊椎动物调查的研究文献在全国各省级行政区、生物多样性热点地区的分布,及其运用的调查方法和技术手段进行了系统的分析和比较。结果表明:相较兽类和两栖爬行类的调查,我国鸟类多样性的调查最多,发表文献占所有文献的70.26%。四川、云南的陆生脊椎动物调查最多,分别发表285篇、260篇文献。分布于我国的4个全球生物多样性热点地区的调查强度存在显著差异,印缅生物多样性热点地区和中国西南山地的研究文献较多,分别为348篇、324篇文献;中亚山地、喜马拉雅山地的研究文献较少,分别为71篇、66篇文献。陆生脊椎动物调查方法主要采用样线法、样点法、样方法和直接计数法,或将上述几种方法综合应用,样线法在所有场景(如:高山冻原、农田、城市等)中应用频率最高;技术手段以直接观察法、采集法、红外相机陷阱法为主,其中直接观察法在所有场景(如城市、湿地、草原等)中应用频率最高。当前,我国陆生脊椎动物调查已取得很多新进展,包括新兴物种采集和物种识别技术的发展(如无人机技术在大型兽类和集群水鸟上的应用、卫星追踪在迁徙鸟类上的应用等)、大数据时代下调查方法的改善和数据管理的提升等。未来我国的陆生脊椎动物调查,应拓宽新兴物种采集方法和识别技术的应用范围,进一步关注和发掘脊椎动物的新调查技术,以大数据为基础完善种群数据分析与调查管理体系,并朝着面向大众、服务社会的方向发展,以引起全社会对生物多样性保护的重视。本文以整体的视角概述了陆生脊椎动物各类群调查的情况,评估了不同地区调查强度的差异,并在调查方法和技术手段方面作了总结和展望,可为未来国内陆生脊椎动物野外调查工作的总体方向、调查侧重、方法运用等方面提供一定的参考。 展开更多
关键词 陆生脊椎动物 野外调查 调查方法 技术手段 生物多样性热点地区
原文传递
Immobilization and characterization of the Lactarius deliciosus mycelia-embedded polylysine-alginate beads and their decolorization performance
19
作者 Yiwen Jin Jie Yuan +4 位作者 Caixia Liu Jiacheng Sun Youbin Liu zhifeng ding Qingxi Wu 《Frontiers of Chemical Science and Engineering》 SCIE EI CSCD 2023年第12期2001-2013,共13页
Liquid fermented fungal mycelia with decolorization capability have potential applications in scale-up. In this work, the Lactarius deliciosus mycelia were immobilized on ε-polylysine-alginate beads, and the decolori... Liquid fermented fungal mycelia with decolorization capability have potential applications in scale-up. In this work, the Lactarius deliciosus mycelia were immobilized on ε-polylysine-alginate beads, and the decolorization effects of ε-polylysine-alginate beads were demonstrated along with Coomassie brilliant blue G-250 as a model dye. Morphology observation confirmed the beads had an exterior film and interior capsule with honeycomb microstructures suitable for mycelia growth. It was manifested that the maximum decolorization efficiency for mycelia was 98.5% at a removal rate of 0.68 mg·L^(-1)·h after 3 days. In comparison, the decolorization efficiency of the immobilized mycelia reached the maximum value of 97.3% at a removal rate of 6.1 mg·L^(-1)·h after 8 h. The enzyme activities of lignin peroxidase and laccase tested in the immobilized mycelia were significantly higher than in that of the free ones, such as the lignin peroxidase had the highest enzyme activity of 77.6 ± 7.4 U·L^(-1) in the former, while of 27.4 ± 8.7 U·L^(-1) in the latter. The immobilization of L. deliciosus mycelia could improve the decolorization of Coomassie brilliant blue G-250 efficiently. The prepared ε-polylysine-alginate beads embedded with L. deliciosus mycelia have very good reusability and a great potential in decolorizing analog dyes. 展开更多
关键词 Lactarius deliciosus mycelia IMMOBILIZATION DECOLORIZATION polylysine-alginate beads Coomassie brilliant blue G-250
原文传递
Insights into enhanced electrochemiluminescence of a multiresonance thermally activated delayed fluorescence molecule
20
作者 Liuqing Yang Lihui Dong +4 位作者 David Hall Mahdi Hesari Yoann Olivier Eli Zysman‐Colman zhifeng ding 《SmartMat》 2023年第2期106-119,共14页
The electrochemiluminescence(ECL)behavior of a multiresonance thermally activated delayed fluorescence molecule has been investigated for the first time by means of ECL‐voltage curves,newly designed ECL‐time observa... The electrochemiluminescence(ECL)behavior of a multiresonance thermally activated delayed fluorescence molecule has been investigated for the first time by means of ECL‐voltage curves,newly designed ECL‐time observatory,and ECL spectroscopy.The compound,Mes3DiKTa,shows complex ECL behavior,including a delayed onset time of 5 ms for ECL generation in both the annihilation pathway and the coreactant route,which we attribute to organic long‐persistent ECL(OLECL).Triplet‐triplet annihilation,thermally activated delayed fluorescence and uncompensated solution resistance cannot be ruled out as contributing mechanisms to the ECL.A very long ECL emission decay was attributed to OLECL as well.The absolute ECL efficiencies of Mes3DiKTa were enhanced and reached 0.0013%in annihilation route and 1.1%for the coreactant system,which are superior to those of most other organic ECL materials.It is plausible that ECL materials with comparable behavior as Mes3DiKTa are desirable in applications such as ECL sensing,imaging,and light‐emitting devices. 展开更多
关键词 ELECTROCHEMILUMINESCENCE multiresonant thermally activated delayed fluorescence organic long‐persistent electrochemiluminescence triplet‐triplet annihilation
原文传递
上一页 1 2 下一页 到第
使用帮助 返回顶部