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Climate change and the conservation of marmots 被引量:1
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作者 Kenneth B. Armitage 《Natural Science》 2013年第5期36-43,共8页
Conservation of marmots, large ground-dwelling squirrels restricted to the northern hemisphere, was impacted by direct human activity through hunting or modifying ecosystem dynamics. Regulating human activities reduce... Conservation of marmots, large ground-dwelling squirrels restricted to the northern hemisphere, was impacted by direct human activity through hunting or modifying ecosystem dynamics. Regulating human activities reduced the threat of extinction. Climate change, an indirect human impact, threatens marmot survival through global warming and extreme weather events. Most marmot species occupy a harsh environment characterized by a short growing season and a long, cold season without food. Marmots cope with seasonality by hibernating. Their large size increases the efficiency of fat accumulation and its use as the sole energy source during hibernation. Marmot physiology is highly adapted to coping with low environmental temperatures;they are stressed by high heat loads. Global warming since the last ice age reduced the geographic distribution of some of the 15 species of marmots. Recent warming resulted in a movement upslope of their lower elevation boundary. This process likely will continue because warming is associated with drier unpalatable vegetation. Drought reduces reproduction and increases mortality;thus decreased summer rainfall in the montane environments where marmots live may cause local extinction. Snow cover, a major environmental factor, is essential to insulate hibernation burrows from low, stressful temperatures. However, prolonged vernal snow cover reduces reproduction and increases mortality. Montane areas currently lacking marmot populations because vernal snow cover persists beyond the time that marmots must begin foraging may become colonized if warming causes earlier snow melt. This benefit will be short-lived because decreased precipitation likely will result in unpalatable vegetation. Although some marmot populations are physiologically adapted to a warmer climate, global warming will increase too rapidly for any significant evolutionary response to dryness. The species that live in high, alpine meadows where tree and shrub invasions occur are most threatened with extinction. Captive breeding can preserve marmot species in the shortrun, but is impractical over the long-term. Widespread species are unlikely to be endangered in the foreseeable future, but local, low elevation populations will be lost. 展开更多
关键词 Climate Change Global WARMING MARMOT SNOWMELT HIBERNATION Temperature
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Value Disclosure of Young Adults Through Social Media in the Iraqi Kurdistan Region as an Emerging Democracy
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作者 Goran Sabah Ghafour 《Journalism and Mass Communication》 2014年第5期303-317,共15页
This study examines how accurate young adults in the Iraqi Kurdistan Region, as an emerging democracy in the Middle East, express their core values through social media (Facebook in this context). It also explores w... This study examines how accurate young adults in the Iraqi Kurdistan Region, as an emerging democracy in the Middle East, express their core values through social media (Facebook in this context). It also explores whether privacy affects with value disclosure. Findings show that value disclosure and definition of privacy varied greatly among respondents and from one value to another. Based on in-depth interview with 12 young adults, the study finds that religious, social, and cultural values have been easily and freely expressed on Facebook accounts by the majority of young adults, whereas other values such as honesty, freedom of speech, and political beliefs are being held by others mainly for privacy issues and political reasons. Democracy was a core value for some young adults seeking to make sense of the western principles of democracy and that reflect on their Facebook account. Results suggest that male respondents practice more freedom and less caution about their privacy than the female respondents on Facebook. 展开更多
关键词 social media DEMOCRACY Iraq PRIVACY FACEBOOK
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APPLICATION OF HIGH-RESOLUTION MAGNETIC METHOD AND GRADIENT METHOD TO LOCATE ABANDONED BRINE-WELLS IN HUTCHINSON, KANSAS, U.S.A.
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作者 CHEN Chao XIA Jianghai +2 位作者 XIA Sihao David Laflen Stephen L. Williams 《工程地球物理学报》 2004年第1期17-25,共9页
After successfully locating one abandoned brine well by an electromagnetic method during testing in 2001 and five abandoned brine wells by a high resolution magnetic method during 2002, a high resolution magnetic meth... After successfully locating one abandoned brine well by an electromagnetic method during testing in 2001 and five abandoned brine wells by a high resolution magnetic method during 2002, a high resolution magnetic method was again proposed to search for wells in 2003 when a second sensor was employed to acquire data for calculating the pseudo vertical gradient of magnetic fields. Total area surveyed in 2003 was 1,024,000 ft 2, which was divided into grids with an average size of 10,000 ft 2 and distributed across eight different sites. Magnetic anomalies and their vertical gradients from known brine wells were first recorded as signatures to identify anomalies caused by possible buried brine wells. Of fifty one verified anomalies, thirty one anomalies were due to wells buried at depths from 0 to 8.5 ft: twenty one 6 to 9 inch abandoned brine wells, seven 1.5 to 3 inch probable water wells, one 16 inch dewatering well for a construction site at a depth of 3 ft, and two 4 inch wells on the ground surface. Approximate monopole shaped anomalies were observed from all these wells after data corrections. However, the range of amplitudes of magnetic anomalies from 7,000 to 28,000 nT from these abandoned brine wells was measured. This range of anomalies is mainly due to the thickness and depth of buried wells. Anomaly amplitudes from 1.5 to 3 inch wells are 4,000 to 8,000 nT and linearly correlate with the buried depth. One 3 inch well that caused an anomaly of 13,000 nT could be the inner pipe of a brine well. Gradient anomalies are roughly in a range of 100 to 200 nT/inch for 1.5 to 3 inch wells and 200 to 300 nT/inch for brine wells.As indicated by the potential field theory, gradient data possess higher horizontal resolution than the magnetic field itself. Gradient data provide valuable assistance in determining horizontal locations of anomaly sources for excavation. In practice, however, improvement in the horizontal resolution is limited by survey line spacing. If only one sensor is used in a survey, there is rapid decrease in the horizontal resolution when sensor height increases from 14 to 44 inches. This indicates that it is critical to keep the sensor as close to the ground as possible when hunting buried wells that are close to each other. It also suggests that the downward continuation is useful to increase the horizontal resolution in well hunting. 展开更多
关键词 High resolution magnetic method Magnetic gradient method Brine Well
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Mating system and genetic diversity of a rare desert legume Ammopiptanthus nanus (Leguminosae) 被引量:2
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作者 Guo-Qing CHEN Hong-Wen HUANG +2 位作者 Daniel J CRAWFORD Bo-Rong PAN Xue-Jun GE 《Journal of Systematics and Evolution》 SCIE CSCD 北大核心 2009年第1期57-66,共10页
Ammopiptanthus nanus is an endangered evergreen shrub endemic to the deserts of central Asia and plays an important role in delaying further desertification. We examined allozyme variation and AFLP diversity in A. nan... Ammopiptanthus nanus is an endangered evergreen shrub endemic to the deserts of central Asia and plays an important role in delaying further desertification. We examined allozyme variation and AFLP diversity in A. nanus populations and investigated the mating system of this species using progeny arrays assayed for polymorphic allozyme loci. Mating system analysis in the Keyi'eryongke'er population showed low levels of outcrossing, and strong inbreeding depression. Low levels of genetic variation were detected at both population (allozyme, Pp=14.0%, A=l.14, He=0.031; AFLP, Pp=14.5%, Shannon's information index I=0.063) and species (allozyme, Pp=21.1%, A=1.21, He=0.040; AFLP, Pp=20.9%, I=0.083) levels; while moderate genetic differentiation existed among populations, as indicated by allozymes (Gsa-=0.081) and AFLP (GST=0.151-0.193). Founder effect, bottlenecks in evolutionary history, the mixed mating system and co-ancestry may have influenced the level of genetic diversity in A. nanus. Markers of both types provide new insights for conservation management, indicating that the Biao'ertuokuoyi and Keyi'eryongke'er populations should be given priority for in situ conservation and regarded as seed sources for ex situ conservation. 展开更多
关键词 AFLP ALLOZYME AMMOPIPTANTHUS conservation endangered plant genetic structure outcrossing rate.
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A NOVEL EOR POLYMER (Ⅱ)——INVESTIGATION ON IN-SITU GELATION OF SMRF SYSTEM IN BEREA CORE
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作者 庄银凤 Stanley McCool +1 位作者 G.Paul Willhite Don W.Green 《Chinese Journal of Polymer Science》 SCIE CAS CSCD 1995年第1期66-73,共8页
In-situ gelation of aqueous sulfomethylated resorcinol formaldehyde (SMRF) system inBerea core has been investigated. Two sets of displacement experiments were conducted with thissystem (containing 5% NaCl, 0. 036% Ca... In-situ gelation of aqueous sulfomethylated resorcinol formaldehyde (SMRF) system inBerea core has been investigated. Two sets of displacement experiments were conducted with thissystem (containing 5% NaCl, 0. 036% CaCl_2. 2H_2O). The brine permeabilities of the coreswere reduced significantly from about 600 to 0.1 md. The in-situ gelation in Berea core occurreda little bit earlier than gelation anticipated from bulk test in the experiments. The gel time waseasier to control at initial pH between 6 and 8. During injection of SMRF system, the apparentviscosity was less than 1 mPa·s at 41℃. 展开更多
关键词 In-situ gelation EOR polymer Oil recovery Sulfomethylated resorcinol formaldehyde
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A NOVEL EOR POLYMER (Ⅰ)—STUDY ON GELATION OF RESORCINOL-FORMALDEHYDE SYSTEMS
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作者 庄银凤 Stanley McCool +1 位作者 G.Paul Willhite Don W.Green 《Chinese Journal of Polymer Science》 SCIE CAS CSCD 1995年第1期59-65,共7页
Factors affecting the gelation of resorcinol-formaldehyde systems have been examined overvariable ranges applicable to oilfield use. Gelation of resorcinol-formaldehyde (RF) system wassensitive to pH,salinity and hard... Factors affecting the gelation of resorcinol-formaldehyde systems have been examined overvariable ranges applicable to oilfield use. Gelation of resorcinol-formaldehyde (RF) system wassensitive to pH,salinity and hardness. Generally,this gel system could be used in fresh water orlow salinity brine at pH higher than about 9. The application would require careful monitoring ofinjection fluids to avoid premature gelation or prolonged shut-in times,especially under conditionsof low salinity and high pH. Salinity and hardness compatibilities of the system were improved bysulfomethylation of resorcinol. Aqueous sulfomethylated resorcinol formaldehyde (SMRF)system could be used in brine with higher salinity and hardness and at a wider pH range of 5--10. 展开更多
关键词 GELATION Resorcinol formaldehyde Oil recovery EOR polymer
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Restrictions on the Material Coefficients in the Constitutive Theories for Non-Classical Viscous Fluent Continua
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作者 K. S. Surana A. D. Joy J. N. Reddy 《Applied Mathematics》 2018年第1期44-85,共42页
This paper considers conservation and balance laws and the constitutive theories for non-classical viscous fluent continua without memory, in which internal rotation rates due to the velocity gradient tensor are incor... This paper considers conservation and balance laws and the constitutive theories for non-classical viscous fluent continua without memory, in which internal rotation rates due to the velocity gradient tensor are incorporated in the thermodynamic framework. The constitutive theories for the deviatoric part of the symmetric Cauchy stress tensor and the Cauchy moment tensor are derived based on integrity. The constitutive theories for the Cauchy moment tensor are considered when the balance of moments of moments 1) is not a balance law and 2) is a balance law. The constitutive theory for heat vector based on integrity is also considered. Restrictions on the material coefficients in the constitutive theories for the stress tensor, moment tensor, and heat vector are established using the conditions resulting from the entropy inequality, keeping in mind that the constitutive theories derived here based on integrity are in fact nonlinear constitutive theories. It is shown that in the case of the simplest linear constitutive theory for stress tensor used predominantly for compressible viscous fluids, Stokes' hypothesis or Stokes'?assumption has no thermodynamic basis, hence may be viewed incorrect. Thermodynamically consistent derivations of the restrictions on various material coefficients are presented for non-classical as well as classical theories that are applicable to nonlinear constitutive theories, which are inevitable if the constitutive theories are derived based on integrity. 展开更多
关键词 Non-Classical CONTINUA Polar CONTINUA EULERIAN Description VISCOUS Fluids MATERIAL COEFFICIENTS
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Measuring Light and Geometry Data of Roadway Environments with a Camera
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作者 Hongyi Cai Linjie Li 《Journal of Transportation Technologies》 2014年第1期44-62,共19页
Evaluation of the conspicuity of roadway environments for their environmental impact on driving performance is vital for roadway safety. Existing meters and tools for roadway measurements cannot record light and geome... Evaluation of the conspicuity of roadway environments for their environmental impact on driving performance is vital for roadway safety. Existing meters and tools for roadway measurements cannot record light and geometry data simultaneously in a high resolution. This study introduced a new method that adopted recently developed high dynamic range (HDR) photogrammetry to measure the luminance and XYZ coordinates of millions of points across a road scene with the same device—a camera, and a MatLab code for data treatment and visualization. To validate this method, the roadway environments of a straight and flat section of Jayhawk Boulevard (482.8 m long) at Lawrence, KS and a roundabout (15.3 m in diameter) at its end were measured under clear and cloudy sky in the daytime and at nighttime with dry and wet pavements. Eight HDR images of the roadway environments under different viewing conditions were generated using the HDR photogrammetric techniques and calibrated. From each HDR image, synchronous light and geometry data were extracted in Radiance and further analyzed to identify potential roadway environmental hazards using the MatLab code (http://people.ku.edu/~h717c996/research.html). The HDR photogrammetric measurement with current equipment had a margin of errors for geometry measurement that varied with the measuring distance, averagely 23.1% - 27.5% for the Jayhawk Boulevard and 9.3% - 16.2% for the roundabout. The accuracy of luminance measurement was proven in the literature as averagely 1.5% - 10.1%. The camera-aided measurement is fast, non-contact, non-destructive, and off the road, thus, it is deemed more efficient and safer than conventional ways using meters and tools. The HDR photogrammetric techniques with current equipment still need improvements on accuracy and speed of the data treatment. 展开更多
关键词 Measurement GEOMETRY LIGHT ROADWAY Environment High Dynamic RANGE PHOTOGRAMMETRY
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Modulated-Power Implantable Neuromodulation Devices and Their Impact on Surrounding Tissue Temperatures
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作者 John R. Stark Sergio R. Romero +2 位作者 John M. Gorman John P. Abraham Ephraim M. Sparrow 《Journal of Biomedical Science and Engineering》 2016年第12期545-562,共18页
This project was intended to determine whether the preprogrammed time-varying recharge protocol for a battery incased in a neuromodulation implant can give rise to tissue temperatures that surpass a safe level or are ... This project was intended to determine whether the preprogrammed time-varying recharge protocol for a battery incased in a neuromodulation implant can give rise to tissue temperatures that surpass a safe level or are otherwise benign. The study included the development of a highly accurate model of all the thermal processes that are activated by the recharging of the battery contained within the neuromodulation implant. The model was implemented by numerical simulations performed for several realistic operating conditions. The computed spatial and temporal tissue temperature distributions were employed to estimate possible tissue damage by making use of two independent methodologies. Independent calorimeter-based experiments were performed to provide validation for the calculated rates of heat generation in the coils of the implant. Spatial and temporal tissue temperature distributions extracted from the numerical simulations revealed the thermal effects associated with several realistic operating protocols. None of the operating protocols gave rise to temperatures above 42℃. Numerical values of thermal tissue damage metrics were determined and compared with accepted values which correspond to the absence and the presence of tissue damage. The experimentally determined rate of heat generation in the implant coils validated that from electrical measurements to within 2%. Both the tissue temperature results and the thermal damage metrics found no evidence of tissue injury when time-varying preprogrammed protocols are used in the recharging of neuromodulation implant-encased batteries. 展开更多
关键词 Biological Heating NEUROSTIMULATION NEUROMODULATION Implant Recharge Thermal Injury Modulated-Power Implant
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多道面波分析方法在测量土壤压实度方面的应用研究 被引量:23
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作者 田钢 石战结 +1 位作者 Don.W.Steeples Jianghai XIA 《地球物理学进展》 CSCD 2003年第3期450-454,共5页
 在农业和工程领域,土壤压实度是一个重要问题.虽然采用钻孔方法可以探测土壤压实度情况,但费用较高.本文采用多道面波分析方法(MASW)研究了土壤压实度的问题,并将试验结果同电阻率测井数据、岩心数据、测井速度做了对比,结果表明该方...  在农业和工程领域,土壤压实度是一个重要问题.虽然采用钻孔方法可以探测土壤压实度情况,但费用较高.本文采用多道面波分析方法(MASW)研究了土壤压实度的问题,并将试验结果同电阻率测井数据、岩心数据、测井速度做了对比,结果表明该方法可以用于土壤压实度的探测,而且速度快、费用低、结果准确可信. 展开更多
关键词 土壤压实度 横波速度 多道面波分析 岩心数据 电阻率测井 测井速度
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沿断层逸出的氢气对地震的诱发作用 被引量:14
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作者 粟启初 E.Zeller E.Angino 《地震学报》 CSCD 北大核心 1992年第2期228-235,259,共8页
试验表明,方解石等非金属材料经短时、低压渗氢处理后显微硬度、晶格常数均明显减小,这意味着氢扩散可引起非金属材料的强度下降、材料弱化.地球内部各种化学反应所生成的氢气及地球形成时其内部所聚集的氢气都要沿断裂带向上迁移,逸出... 试验表明,方解石等非金属材料经短时、低压渗氢处理后显微硬度、晶格常数均明显减小,这意味着氢扩散可引起非金属材料的强度下降、材料弱化.地球内部各种化学反应所生成的氢气及地球形成时其内部所聚集的氢气都要沿断裂带向上迁移,逸出,在其逸出的同时将明显降低岩石、岩层的强度,使断层在低构造应力作用下有可能发生断裂.氢气浓度异常从现象上看是被动的、断层活动的反映,而氢气逸出本身对断层运动却有能动的诱发作用. 展开更多
关键词 氢气 异常 地震 前兆 断层 诱震
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Multi-hazard socio-physical resilience assessment of hurricane-induced hazards on coastal communities
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作者 Omar M.Nofal Kooshan Amini +7 位作者 Jamie E.Padgett John W.van de Lindt Nathanael Rosenheim Yousef M.Darestani Amin Enderami Elaina J.Sutley Sara Hamideh Leonardo Duenas-Osorio 《Resilient Cities and Structures》 2023年第2期67-81,共15页
Hurricane-induced hazards can result in significant damage to the built environment cascading into major impacts to the households,social institutions,and local economy.Although quantifying physical impacts of hurrica... Hurricane-induced hazards can result in significant damage to the built environment cascading into major impacts to the households,social institutions,and local economy.Although quantifying physical impacts of hurricane-induced hazards is essential for risk analysis,it is necessary but not sufficient for community resilience planning.While there have been several studies on hurricane risk and recovery assessment at the building-and community-level,few studies have focused on the nexus of coupled physical and social disruptions,particularly when char-acterizing recovery in the face of coastal multi-hazards.Therefore,this study presents an integrated approach to quantify the socio-physical disruption following hurricane-induced multi-hazards(e.g.,wind,storm surge,wave)by considering the physical damage and functionality of the built environment along with the population dynamics over time.Specifically,high-resolution fragility models of buildings,and power and transportation infrastructures capture the combined impacts of hurricane loading on the built environment.Beyond simulat-ing recovery by tracking infrastructure network performance metrics,such as access to essential facilities,this coupled socio-physical approach affords projection of post-hazard population dislocation and temporal evolution of housing and household recovery constrained by the building and infrastructure recovery.The results reveal the relative importance of multi-hazard consideration in the damage and recovery assessment of communities,along with the role of interdependent socio-physical system modeling when evaluating metrics such as housing recovery or the need for emergency shelter.Furthermore,the methodology presented here provides a foundation for resilience-informed decisions for coastal communities. 展开更多
关键词 Fragility analysis Hurricane damage Probabilistic damage assessment Transportation network Power network Housing recovery population impacts
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基于驾驶员路径选择的动态交通仿真模型 被引量:8
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作者 李强 缪立新 段进宇 《公路交通科技》 CAS CSCD 北大核心 2001年第6期65-69,共5页
描述一个基于路径的动态交通仿真模型 (RDTS) ,它使用一个微观交通流仿真器结合一个驾驶员路径策划器来实现路网中每辆车从出发地到目的地行程的模拟。应用开发的时间相关最短路模型 ,驾驶员在向目的地前进途中可以根据交通条件的动态... 描述一个基于路径的动态交通仿真模型 (RDTS) ,它使用一个微观交通流仿真器结合一个驾驶员路径策划器来实现路网中每辆车从出发地到目的地行程的模拟。应用开发的时间相关最短路模型 ,驾驶员在向目的地前进途中可以根据交通条件的动态变化而动态地选择和变更路径。RDTS模型采用一个路径选择模型来模拟详细的动态交通分配过程 ,并且致力于反映路网中个别车辆的行为表现及其相互作用 ,其中包含车辆生成、路径选择和车辆移动模型 ,可以很好地应用于驾驶员动态路径诱导领域。 展开更多
关键词 动态交通仿真 道路网络 车辆生成 路径选择 车辆移动仿真
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缝洞型油藏填充介质含水饱和度对CO_(2)和N_(2)溶解扩散影响实验 被引量:1
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作者 王志兴 侯吉瑞 +1 位作者 杨宇昊 朱桂良 《特种油气藏》 CAS CSCD 北大核心 2022年第1期91-98,共8页
为深入认识缝洞型油藏注CO_(2)、N_(2)启动缝洞体内部填充介质中剩余油的作用机理,采用压力衰竭实验方法,测量气体扩散系数和溶解度,研究含水饱和度对2种注入气的扩散压力、溶解度和扩散系数的影响规律,分析真实油藏条件下填充介质含水... 为深入认识缝洞型油藏注CO_(2)、N_(2)启动缝洞体内部填充介质中剩余油的作用机理,采用压力衰竭实验方法,测量气体扩散系数和溶解度,研究含水饱和度对2种注入气的扩散压力、溶解度和扩散系数的影响规律,分析真实油藏条件下填充介质含水饱和度对CO_(2)和N_(2)溶解扩散的作用机理。实验结果表明:填充介质内部含水饱和度由束缚水条件增至完全饱和,CO_(2)和N_(2)的压力降幅分别为41.62%、43.22%,溶解度降幅分别为40.16%、42.50%,扩散系数均降低一个数量级;填充介质中地层水的存在降低了注入气的溶解和扩散传质能力,地层流体物性和地层流体与多孔介质间的差异是其主要影响因素。该研究为缝洞型油藏高含水阶段的剩余油注气开发以及相关参数优化提供参考。 展开更多
关键词 缝洞型油藏 填充介质 含水饱和度 气体溶解与扩散 CO_(2) N_(2)
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Smart contract-enabled consortium blockchains for the control of supply chain information distortion 被引量:1
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作者 Corban Allenbrand 《Blockchain(Research and Applications)》 EI 2023年第3期11-17,共7页
Conflicts between supply chain members emerge because individual strategic actions may not be jointly optimal.Efforts to forecast consumer demand represent a source of conflict.The coordination of forecasts requires a... Conflicts between supply chain members emerge because individual strategic actions may not be jointly optimal.Efforts to forecast consumer demand represent a source of conflict.The coordination of forecasts requires a powerful incentive alignment approach.This work proposes a smart contract equipped consortium blockchain system that creates an incentive structure that makes coordination with respect to forecasts economically appealing.Distortions of demand information due to uncoordinated forecasting are captured by a bullwhip measure that factors both forecast error and variance.Cooperation under the system is shown to help minimize this bullwhip measure,thus generating new outcomes for the participants that allow for a higher reward.Under a fixed payout structure,the system achieves credibility of continued cooperation,thus promoting an optimally coordinated equilibrium between the retailer and supplier.Blockchain technology represents a novel information system and consensus formation mechanism that can intermediate the behavior of a supply chain network. 展开更多
关键词 Game theory BULLWHIP Information systems Supply chain coordination Demand forecasting Blockchain applications
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雌、雄草原田鼠外周骨骼肌肌球蛋白重链的表达(英文) 被引量:1
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作者 Andrew C. FRY Michael H. FERKIN +4 位作者 Brian K. SCHILLING Stuart T. LEONARD Matthew P. HARBER Martyn R. RUBIN J. Chadwick SMITH 《动物学报》 SCIE CAS CSCD 北大核心 2008年第1期104-110,共7页
已往的研究对于实验室应用的各种啮齿类动物,如大鼠和小鼠骨骼肌蛋白表达的特性已有报道。然而,至今不清楚其它啮齿类动物如野生鼠骨骼肌蛋白的表达或性双态性的特征,而这些野生鼠的行为学、形态学及生理学特点均已有报道。已知骨骼肌... 已往的研究对于实验室应用的各种啮齿类动物,如大鼠和小鼠骨骼肌蛋白表达的特性已有报道。然而,至今不清楚其它啮齿类动物如野生鼠骨骼肌蛋白的表达或性双态性的特征,而这些野生鼠的行为学、形态学及生理学特点均已有报道。已知骨骼肌的肌球蛋白重链( MHC)成分与其功能特性有关。我们研究了草原田鼠的肱三头肌、胫骨前肌、腓肠肌和比目鱼肌MHC蛋白表达的性别特性。应用SDS聚丙烯酰胺凝胶电泳法测定MHCⅠ型、Ⅱa型、Ⅱd/x和Ⅱb型的蛋白表达相对含量。结果表明:与雌鼠相比,雄鼠的比目鱼肌湿重较大,胫骨前肌的MHCⅡa蛋白量表达较高。未见骨骼肌重量及MHC蛋白表达含量在雌雄鼠间的性别差异。血中睾酮的浓度差异可能不影响外周骨骼肌蛋白的表达特性。然而,与过去在大鼠、兔和小鼠中的已报道的结果相比,草原田鼠骨骼肌MHC的表达显示了更多异质性。推测这可能与草原田鼠和其它小型哺乳类动物生存的自然环境和功能需要有关。 展开更多
关键词 性二态性 骨骼肌 蛋白同分异构 性别
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川东地区早中三叠世海水碳氧同位素特征及其成钾意义
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作者 丁婷 刘成林 +2 位作者 郭福生 袁苗 Robert Goldstein 《盐湖研究》 CAS CSCD 2023年第4期23-29,共7页
早中三叠世是地球发展史上的一个特殊时期,主要在于其特殊的海陆分布及气候特征,其海水的演化特征一直为人们所关注。文章对四川盆地东部地区的85个碳酸盐岩碳、氧同位素地球化学特征进行了研究,也对海水原始性进行了分析和判断,同时对... 早中三叠世是地球发展史上的一个特殊时期,主要在于其特殊的海陆分布及气候特征,其海水的演化特征一直为人们所关注。文章对四川盆地东部地区的85个碳酸盐岩碳、氧同位素地球化学特征进行了研究,也对海水原始性进行了分析和判断,同时对海水原始性好的样品进行了碳氧同位素的测试,并运用其结果对古水温进行了估算。研究结果表明,四川盆地东部早中三叠世海相碳酸盐岩沉积期海水温度比较高,飞仙关组期的平均温度为42.30℃,嘉陵江组期的平均温度为43.89℃,雷口坡组期的温度为43.61℃。这与该区测试的石盐流体包裹体的均一温度具有一致性,说明当时早中三叠世的古海水具有较高的温度,高温的气候特征有利于海水的蒸发和浓缩,为钾镁盐的形成提供了气候条件。 展开更多
关键词 古气候 成钾效应 早中三叠世 四川东部
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一类7次Z2-等变平面Hamilton系统相图的分类
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作者 孔德强 郭洪霞 张明吉 《科技信息》 2006年第04S期139-140,共2页
考虑了一类7次一等面Hamikon向量场,通过定性分析和数值计算获得如下结果:具有最多奇点个数时此向量场的相图至少有9种:
关键词 相图 相轨道 等平面Hamilton向量场
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Vision-based fatigue crack detection using global motion compensation and video feature tracking
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作者 Rushil Mojidra Jian Li +3 位作者 Ali Mohammadkhorasani Fernando Moreu Caroline Bennett William Collins 《Earthquake Engineering and Engineering Vibration》 SCIE EI CSCD 2023年第1期19-39,共21页
Fatigue cracks that develop in civil infrastructure such as steel bridges due to repetitive loads pose a major threat to structural integrity.Despite being the most common practice for fatigue crack detection,human vi... Fatigue cracks that develop in civil infrastructure such as steel bridges due to repetitive loads pose a major threat to structural integrity.Despite being the most common practice for fatigue crack detection,human visual inspection is known to be labor intensive,time-consuming,and prone to error.In this study,a computer vision-based fatigue crack detection approach using a short video recorded under live loads by a moving consumer-grade camera is presented.The method detects fatigue crack by tracking surface motion and identifies the differential motion pattern caused by opening and closing of the fatigue crack.However,the global motion introduced by a moving camera in the recorded video is typically far greater than the actual motion associated with fatigue crack opening/closing,leading to false detection results.To overcome the challenge,global motion compensation(GMC)techniques are introduced to compensate for camera-induced movement.In particular,hierarchical model-based motion estimation is adopted for 2D videos with simple geometry and a new method is developed by extending the bundled camera paths approach for 3D videos with complex geometry.The proposed methodology is validated using two laboratory test setups for both in-plane and out-of-plane fatigue cracks.The results confirm the importance of motion compensation for both 2D and 3D videos and demonstrate the effectiveness of the proposed GMC methods as well as the subsequent crack detection algorithm. 展开更多
关键词 global motion compensation fatigue crack detection computer vision parallax effect distortion induced fatigue crack video stabilization camera motion in-plane fatigue crack out-of-plane fatigue crackanalysis
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Chronic training status affects muscle excitation of the vastus lateralis during repeated contractions
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作者 Sunggun Jeon Stephanie A.Sontag +1 位作者 Trent J.Herda Michael A.Trevino 《Sports Medicine and Health Science》 2023年第1期42-49,共8页
This study examined electromyographic amplitude(EMGRMS)-force relationships during repeated submaximal knee extensor muscle actions among chronic aerobically-(AT),resistance-trained(RT),and sedentary(SED)individuals.F... This study examined electromyographic amplitude(EMGRMS)-force relationships during repeated submaximal knee extensor muscle actions among chronic aerobically-(AT),resistance-trained(RT),and sedentary(SED)individuals.Fifteen adults(5/group)attempted 20 isometric trapezoidal muscle actions at 50%of maximal strength.Surface electromyography(EMG)was recorded from vastus lateralis(VL)during the muscle actions.For the first and last successfully completed contractions,linear regression models were fit to the log-transformed EMGRMS-force relationships during the linearly increasing and decreasing segments,and the b terms(slope)and a terms(antilog of y-intercept)were calculated.EMGRMS was averaged during steady force.Only the AT completed all 20 muscle actions.During the first contraction,the b terms for RT(1.3010.197)were greater than AT(0.9100.123;p?0.008)and SED(0.9120.162;p?0.008)during the linearly increasing segment,and in comparison to the linearly decreasing segment(1.0180.139;p?0.014),respectively.For the last contraction,the b terms for RT were greater than AT during the linearly increasing(RT?1.3730.353;AT?0.8830.129;p?0.018)and decreasing(RT?1.5260.328;AT?0.9700.223;p?0.010)segments.In addition,the b terms for SED increased from the linearly increasing(0.9680.144)to decreasing segment(1.2680.126;p?0.015).There were no training,segment,or contraction differences for the a terms.EMGRMS during steady force increased from the first-([64.0851.68]μV)to last-contraction([86.7349.55]μV;p?0.001)collapsed across training statuses.The b terms differentiated the rate of change for EMGRMS with increments in force among training groups,indicating greater muscle excitation to the motoneuron pool was necessary for the RT than AT during the linearly increasing and decreasing segments of a repetitive task. 展开更多
关键词 ELECTROMYOGRAPHY Fatigue Isometric trapezoidal muscle action Motor unit control properties Natural log-transformed model Vastus lateralis
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