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Coping with the Impact of Climate Change: A Dive into Precision Agriculture in the United States
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作者 Oluwaseun Ibukun Kehinde Oke Olawale Oluwafemi 《Journal of Agricultural Chemistry and Environment》 2024年第2期208-222,共15页
With the continued increase in the number of people that are food insecure globally, which could be increasing because of the ongoing Ukraine-Russia war, leading to reduction in international agribusinesses, coupled w... With the continued increase in the number of people that are food insecure globally, which could be increasing because of the ongoing Ukraine-Russia war, leading to reduction in international agribusinesses, coupled with drastic climate change exacerbating the problem of food insecurity, there is a constant need to come up with innovative approaches to solve this global issue. In this article, we articulated how precision agriculture can be a tool for ensuring food security in the United States. This study aims to reiterate the significance of precision agriculture in solving global food insecurity. 展开更多
关键词 United States Food Insecurity Precision Agriculture positioning Systems Climate change
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Monitoring of Coastal Subsidence Changes Based on GNSS Positioning and GNSS-IR
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作者 Xiaolei WANG Zijin NIU +1 位作者 Xiufeng HE Runchuan LI 《Journal of Geodesy and Geoinformation Science》 CSCD 2023年第2期71-80,共10页
Coastal subsidence monitoring typically employs Global Navigation Satellite System(GNSS)positioning technology.This method provides information only about subsidence below the station base.Sediments in coastal areas t... Coastal subsidence monitoring typically employs Global Navigation Satellite System(GNSS)positioning technology.This method provides information only about subsidence below the station base.Sediments in coastal areas tend to accumulate quickly,and subsidence can change significantly due to compaction and alluvium.Therefore,monitoring subsidence above the base is essential to obtain overall coastal subsidence.A new technology called GNSS-Interferometric Reflectometry(GNSS-IR)has been recently developed,which can utilize multipath effects to monitor reflector height.Since the base of the GNSS station is deep and the base length remains constant,the height changes measured by the GNSS-IR technology can reflect subsidence above the base.Accordingly,this paper employs GNSS-IR technology to measure subsidence changes above the base.Additionally,GNSS positioning technology is used to obtain subsidence changes below the base,and the overall subsidence change is then calculated using both GNSS-IR and GNSS positioning technology.The Mississippi River Delta,known for its significant sediment thickness,was selected as the study area,and data from FSHS,GRIS,and MSIN stations was analyzed.The results demonstrate that GNSS-IR can be used to measure the subsidence rate above the base,and the corrected overall subsidence rate is equivalent to the relative sea level rise rate. 展开更多
关键词 GNSS-IR GNSS positioning coastal subsidence changes subsidence changes above the base overall subsidence changes
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Change of Teachers' Roles in the Intensive Reading Class
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作者 李喜芬 《河南教育学院学报(哲学社会科学版)》 2001年第4期148-150,共3页
This paper gives an account of characteristics of the intensive reading in English teaching, and change of teachers’ roles in the learner-centered teaching approach. Suggestions are put forward as to how to be a qual... This paper gives an account of characteristics of the intensive reading in English teaching, and change of teachers’ roles in the learner-centered teaching approach. Suggestions are put forward as to how to be a qualified teacher in the intensive reading class accordingly. 展开更多
关键词 teachers roles change intensive reading
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Characteristics and utility of combined duplex color-coded ultrasonography in the cervical rotational position with head MRI and MRA in the differential diagnosis of apogeotropic direction-changing positional nystagmus 被引量:1
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作者 Tessei Kuruma Mariko Arimoto Yasushi Fujimoto 《Journal of Otology》 CSCD 2023年第2期85-90,共6页
Objective:To determine whether cervical ultrasonography,magnetic resonance imaging(MRI),and magnetic resonance angiography(MRA)are useful in the differential diagnosis of etiology and understanding the pathophysiology... Objective:To determine whether cervical ultrasonography,magnetic resonance imaging(MRI),and magnetic resonance angiography(MRA)are useful in the differential diagnosis of etiology and understanding the pathophysiology in cases of apogeotropic direction-changing positional nystagmus(DCPN).Methods:Thirty patients with apogeotropic DCPN were classified into 11 cases of central disease,seven cases of mixed central and peripheral disease,and 12 cases of peripheral disease by differential diagnosis based on various balance function,neuro-otological,and imaging tests.Cervical ultrasonography using the cervical rotation method and MRI and MRA of the head and neck were performed in most patients with apogeotropic DCPN.We reviewed the presence of abnormal imaging findings according to the disease etiology.Results:Of the 30 patients with apogeotropic DCPN,23 showed vascular abnormalities or central lesions on imaging.Vascular lesions were found in six of the 12 patients with peripheral disease.Cervical ultrasonography with cervical rotation detected blood flow disturbance in the vertebral artery in eight patients in whom the disturbance could not be detected by MRI or MRA of the head and neck.Discussion:We hypothesize that the causative disease of apogeotropic DCPN may be strongly associated with circulatory insufficiency of the vertebrobasilar and carotid arteries,and that impaired blood flow in these vessels may affect peripheral vestibular and central function.In patients with apogeotropic DCPN,examinations of vestibular function,central nervous system symptoms,and brain hemodynamics are valuable for differential diagnosis. 展开更多
关键词 Apogeotropic direction changing positional NYSTAGMUS Vertebrobasilar artery Vertebrobasilar insufficiency(VBI) ULTRASONOGRAPHY MRI MRA
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THE POSITIVE SOLUTION OF CLASSICAL GELFAND MODEL WITH COEFFICIENT THAT CHANGE SIGN
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作者 YAO Qing-liu(姚庆六) 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI 2002年第12期1458-1463,共6页
The existence and iteration of positive solution for classical Gelfand models are considered, where the coefficient of nonlinear term is allowed to change sign in [0, 1]. By using the monotone iterative technique, an ... The existence and iteration of positive solution for classical Gelfand models are considered, where the coefficient of nonlinear term is allowed to change sign in [0, 1]. By using the monotone iterative technique, an existence theorem of positive solution is obtained, corresponding iterative process and convergence rate are given. This iterative process starts off with zero function, hence the process is simple, feasible and effective. 展开更多
关键词 Gelfand model coefficient changed sign positive solution existence monotone iterative technique
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Damage Position of Concrete Beam Based on Test of Even Change Point
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作者 张开鹏 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2004年第3期72-73,共2页
The quantitative analysis of damage position of concrete beam is established.The method of damage position free of models used in this paper is based on the variations of strain mode and test of even change point.The ... The quantitative analysis of damage position of concrete beam is established.The method of damage position free of models used in this paper is based on the variations of strain mode and test of even change point.The discrete model and the position criterion are presented.Numerical example is conducted,the result demonstrates that the method of damage position is correct and effective. 展开更多
关键词 test of even change point strain mode damage position
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Changes in Barents Sea Ice Edge Positions in the Last 442 Years. Part 2: Sun, Moon and Planets
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作者 Jan-Erik Solheim Stig Falk-Petersen +2 位作者 Ole Humlum Nils-Axel Mö rner 《International Journal of Astronomy and Astrophysics》 2021年第2期279-341,共63页
This is the second paper in a series of two, which analyze the position of the Barents Sea ice-edge (BIE) based on a 442-year long dataset to understand its time variations. The data have been collected from ship-logs... This is the second paper in a series of two, which analyze the position of the Barents Sea ice-edge (BIE) based on a 442-year long dataset to understand its time variations. The data have been collected from ship-logs, polar expeditions, and hunters in addition to airplanes and satellites in recent times. Our main result is that the BIE position alternates between a southern and a northern position followed by Gulf Stream Beats (GSBs) at the occurrence of deep solar minima. We decompose the low frequency BIE position variations in cycles composed of dominant periods which are related to the Jose period of 179 years, indicating planetary forcings. We propose that the mechanism transferring planetary signals into changes in BIE position is the solar wind (SW), which provides magnetic shielding of the Earth in addition to geomagnetic disturbances. Increase in the solar wind produces pressure which decelerates the Earth’s rotation. It also transfers electrical energy to the ring current in the earth’s magnetosphere. This current magnetizes the earth’s solid core and makes it rotate faster. To conserve angular momentum the earth’s outer fluid mantle rotates slower with a delay of about 100 years. In addition will geomagnetic storms, initiated by solar coronal mass ejections (CMEs) penetrate deep in the Earth’s atmosphere and change pressure pattern in the Arctic. This effect is larger during solar minima since the magnetic shielding then is reduced. The Arctic may then experience local warming. The transition of solar activities to a possibly deep and long minimum in the present century may indicate Arctic cooling and the BIE moving south this century. For the North Atlantic region, effects of the BIE expanding southward will have noticeable consequences for the ocean bio-production from about 2040. 展开更多
关键词 Barents Sea Ice Edge position Cyclic and Non-Linear changes Lunar and Solar Forcing Planetary Orbit Synchronization
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Dependence of Gravity Induced Absorption Changes on the Earth’s Magnetic Field as Measured during Parabolic Flight Campaigns
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作者 Werner Schmidt 《Journal of Modern Physics》 2013年第11期1546-1553,共8页
Various spectroscopic experiments performed on the AIRBUS ZERO G—located in Bordeaux, France—in the years 2002 to 2012 exhibit minute optical reflection/absorption changes (GIACs) as a result of gravitational change... Various spectroscopic experiments performed on the AIRBUS ZERO G—located in Bordeaux, France—in the years 2002 to 2012 exhibit minute optical reflection/absorption changes (GIACs) as a result of gravitational changes between 0 and 1.8 g in various biological species such as maize, oats, Arabidopsis and particularly Phycomyces sporangiophores. During a flight day, the AIRBUS ZERO G conducts 31 parabolas, each of which lasts about three minutes including a period of 22 s of weightlessness. So far, we participated in 11 parabolic flight campaigns including more than 1000 parabolas performing various kinds of experiments. During our campaigns, we observed an unexplainable variability of the measuring signals (GIACs). Using GPS-positioning systems and three dimensional magnetic field sensors, these finally were traced back to the changing earth’s magnetic field associated with the various flight directions. This is the first time that the interaction of gravity and the Earth’ magnetic field in the primary induction process in living system has been observed. 展开更多
关键词 MDWS(Micro Dual Wavelength Spectrometer) GIAC(Gravity Induced Absorption change) AIRBUS-300-ZERO-G Parabolic Flight Micro-and Hypergravity Three Dimensional Earth’s Magnetic Field Global positioning System(GPS) Google Earth
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The Kinematics Performance of Self-Propelled Full Freedom Filament in Wakes of Flow around Cylinder
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作者 Jiyao Yang Yun Liu Guoyi He 《Journal of Applied Mathematics and Physics》 2023年第10期2913-2922,共10页
In vortex streets, the kinematics performance of self-propelled full freedom filament is closely related to the length and the position of filaments in the flow field. In this paper, the changes of passive propulsion ... In vortex streets, the kinematics performance of self-propelled full freedom filament is closely related to the length and the position of filaments in the flow field. In this paper, the changes of passive propulsion velocity and pressure of full-degree-of-freedom filaments after cylindrical wake were analyzed by 15 sets of experiments when the length and position of filaments were changed. The results show that the propulsive velocity of the filament, it approximately increases first and then decreases with the filament length increasing, and the further away from the center of the cylinder, the smaller the propulsive velocity of the filament. In addition, the longer the filament length and the further it is from the center of the cylinder, the lower the pressure around the filament. Experiments show that filaments without energy input can obtain energy from the surrounding flow field to maintain self-propelled motion. Studying the influence of length and position on the kinematics of filaments is helpful to provide a reference for revealing the hydrodynamic mechanism on passive propulsion process and developing low resistance energy harvesting device in swimming fish movement. 展开更多
关键词 Length position change Full Freedom Filaments Passive Propulsion
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Coseismic gravity and displacement changes of Japan Tohoku earthquake(Mw 9.0) 被引量:2
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作者 Xinlin Zhang Shuhei Okubo +1 位作者 Yoshiyuki Tanaka Hui Li 《Geodesy and Geodynamics》 2016年第2期95-100,共6页
The greatest earthquake in the modern history of Japan and probably the fourth greatest in the last 100 years in the world occurred on March 11, 2011 off the Pacific coast of Tohoku.Large tsunami and ground motions ca... The greatest earthquake in the modern history of Japan and probably the fourth greatest in the last 100 years in the world occurred on March 11, 2011 off the Pacific coast of Tohoku.Large tsunami and ground motions caused severe damage in wide areas, particularly many towns along the Pacific coast. So far, gravity change caused by such a great earthquake has been reported for the 1964 Alaska and the 2010 Maule events. However, the spatial-temporal resolution of the gravity data for these cases is insufficient to depict a co-seismic gravity field variation in a spatial scale of a plate subduction zone. Here, we report an unequivocal co-seismic gravity change over the Japanese Island, obtained from a hybrid gravity observation(combined absolute and relative gravity measurements). The time interval of the observation before and after the earthquake is within 1 year at almost all the observed sites, including 13 absolute and 16 relative measurement sites, which deduced tectonic and environmental contributions to the gravity change. The observed gravity agrees well with the result calculated by a dislocation theory based on a self-gravitating and layered spherical earth model. In this computation, a co-seismic slip distribution is determined by an inversion of Global Positioning System(GPS) data. Of particular interest is that the observed gravity change in some area is negative where a remarkable subsidence is observed by GPS, which can not be explained by simple vertical movement of the crust. This indicated that the mass redistribution in the underground affects the gravity change. This result supports the result that Gravity Recovery and Climate Experiment(GRACE) satellites detected a crustal dilatation due to the 2004 Sumatra earthquake by the terrestrial observation with a higher spatial and temporal resolution. 展开更多
关键词 Tohoku earthquake(Mw 9.0) Co-seismic gravity change Co-seismic displacement change Coseismic geoid change Dislocation theory Global positioning System Absolute gravity measurement Relative gravity measurement
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Closed circle DNA algorithm of change positive-weighted Hamilton circuit problem 被引量:5
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作者 Zhou Kang Tong Xiaojun Xu Jin 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2009年第3期636-642,共7页
Chain length of closed circle DNA is equal. The same closed circle DNA's position corresponds to different recognition sequence, and the same recognition sequence corresponds to different foreign DNA segment, so clos... Chain length of closed circle DNA is equal. The same closed circle DNA's position corresponds to different recognition sequence, and the same recognition sequence corresponds to different foreign DNA segment, so closed circle DNA computing model is generalized. For change positive-weighted Hamilton circuit problem, closed circle DNA algorithm is put forward. First, three groups of DNA encoding are encoded for all arcs, and deck groups are designed for all vertices. All possible solutions are composed. Then, the feasible solutions are filtered out by using group detect experiment, and the optimization solutions are obtained by using group insert experiment and electrophoresis experiment. Finally, all optimization solutions are found by using detect experiment. Complexity of algorithm is concluded and validity of DNA algorithm is explained by an example. Three dominances of the closed circle DNA algorithm are analyzed, and characteristics and dominances of group delete experiment are discussed. 展开更多
关键词 closed circle DNA computing model change positive-weighted Hamilton circuit problem group insert experiment group delete experiment.
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Investigating Translators' Positioning via the Appraisal Theory: A Case Study of the Q&A Part of a Speech Delivered by the U.S. Vice President Cheney 被引量:1
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作者 QIAN Hong 《Sino-US English Teaching》 2012年第12期1775-1787,共13页
Appraisal Theory is a part of the interpersonal metafunction in Systemic Functional Linguistics to reveal the speaker's attitudes and positionings. Some scholars in recent years have introduced this theory to the Chi... Appraisal Theory is a part of the interpersonal metafunction in Systemic Functional Linguistics to reveal the speaker's attitudes and positionings. Some scholars in recent years have introduced this theory to the Chinese reader and applied it to the study of different genres, but up to now, very little has been done to test this newly developed theory in translation studies. This paper attempts to use the Appraisal Theory as a tool to investigate speaker's positioning in ST (source text) and TT (target text). The translations of part of the Q&A (Question&Answer) section of the Vice President Cheney's speech at Fudan University and their STs will be investigated in the present study. The source and target texts are first described in the appraisal theoretical framework and then compared to find out the differences in terms of the speaker's positioning in ST and TT. Finally, a discussion is carried out to explore possible reasons that caused the speaker's changed positioning from ST and TT. Our findings indicate that translator's role, linguistic characteristics, and translation purpose might all contribute to speaker's changed positioning. 展开更多
关键词 Appraisal theory ENGAGEMENT changed positioning REASONS
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Coexistence of positive and negative magnetic entropy changes in CeMn_2(Si_(1-x)Ge_x)_2 compounds
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作者 左文亮 胡凤霞 +1 位作者 孙继荣 沈保根 《Chinese Physics B》 SCIE EI CAS CSCD 2015年第9期444-447,共4页
A series of CeMn2(Si1-xGex)2(x = 0.2, 0.4, 0.6, 0.8) compounds are prepared by the arc-melting method. All the samples primarily crystallize in the Th Cr2Si2-type structure. The temperature dependences of zero-fie... A series of CeMn2(Si1-xGex)2(x = 0.2, 0.4, 0.6, 0.8) compounds are prepared by the arc-melting method. All the samples primarily crystallize in the Th Cr2Si2-type structure. The temperature dependences of zero-field-cooled(ZFC) and FC magnetization measurements show a transition from antiferromagnetic(AFM) state to ferromagnetic(FM) state at room temperature with the increase of the Ge concentration. For x = 0.4, the sample exhibits two kinds of phase transitions with increasing temperature: from AFM to FM and from FM to paramagnetic(PM) at around TN-197 K and T C-300 K,respectively. The corresponding Arrott curves indicate that the AFM–FM transition is of first-order character and the FM–PM transition is of second-order character. Meanwhile, the coexistence of positive and negative magnetic entropy changes can be observed, which are corresponding to the AFM–FM and FM–PM transitions, respectively. 展开更多
关键词 magnetocaloric effect CeMn2(Si0.6Ge0.4)2 compound metamagnetic transition positive entropy change
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Body Position Changes Influence Stroke Volume Variation in Mechanically Ventilated Patients with Sepsis 被引量:3
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《麻醉与监护论坛》 2012年第1期26-31,共6页
关键词 摘要 编辑部 编辑工作 读者
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The Issue of Self-concept:Perceptions of Chinese Student Teachers about Their Roles
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作者 Li Hui 《学术界》 CSSCI 北大核心 2013年第6期262-268,共7页
This article has presented some stereotypical views held by Western people about Chinese teachers,and then clarified these misperceptions caused by Western people's different understanding of the meanings of "... This article has presented some stereotypical views held by Western people about Chinese teachers,and then clarified these misperceptions caused by Western people's different understanding of the meanings of "teacher authority","double parental identities",and"strictness"compared to their Chinese counterparts.Then a case study of three Chinese student teachers studying in one Australian university is conducted to analyze their feelings and experiences of teaching in Australia.Finally,the study suggests that Chinese teacher must retain the essence of Chinese good teachers while adopting the advantages of Western teaching culture to improve his / her own teaching practice,and if so,these self changes could be significant to recreate themselves as new Chinese teachers. 展开更多
关键词 新中国 教师 学生 发行 澳大利亚 教学经验 教学文化 教学实践
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Reconstructing Prior Beliefs through Teacher Education Programs——Review of Research into Changes in Language Teacher Beliefs
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作者 WANG Rui 《海外英语》 2013年第5X期101-103,共3页
This review of research into changes in language teacher beliefs reveals that carefully designed language teacher education courses are effective in reconstructing teachers'prior beliefs. When teaching practices a... This review of research into changes in language teacher beliefs reveals that carefully designed language teacher education courses are effective in reconstructing teachers'prior beliefs. When teaching practices are added to the teacher education programs, when adjustments are made to the structure of teacher education courses, and when research practices are incorporated in teacher education programs, significant changes are seen in teachers'beliefs. 展开更多
关键词 TEACHER BELIEFS TEACHER EDUCATION reconstructing c
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Existence of Monotone Positive Solution for a Fourth-Order Three-Point BVP with Sign-Changing Green’s Function
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作者 Junrui Yue Yun Zhang Qingyue Bai 《Open Journal of Applied Sciences》 2024年第1期63-69,共7页
This paper is concerned with the following fourth-order three-point boundary value problem , where , we discuss the existence of positive solutions to the above problem by applying to the fixed point theory in cones a... This paper is concerned with the following fourth-order three-point boundary value problem , where , we discuss the existence of positive solutions to the above problem by applying to the fixed point theory in cones and iterative technique. 展开更多
关键词 Fourth-Order Three-Point Boundary Value Problem Sign-Changing Green’s Function Fixed Point Index Iterative Technique Monotone Positive Solution EXISTENCE
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Investigation of the binding behavior of human serum albumin and phosphorothioate oligodeoxynucleotide
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作者 叶国柱 张亮仁 张礼和 《Journal of Chinese Pharmaceutical Sciences》 CAS 2007年第1期9-13,共5页
Aim To study the binding behavior between human serum albumin (HSA) and phosphorothioate oligodeoxynucleotide (PS- ODN) and the effects of bivalent cations on the interaction. Methods Surface plasma resonance, cir... Aim To study the binding behavior between human serum albumin (HSA) and phosphorothioate oligodeoxynucleotide (PS- ODN) and the effects of bivalent cations on the interaction. Methods Surface plasma resonance, circular dichroism and fluorescence experiments were conducted. Results ( 1 ) the binding ability was decreased along with the increase of pH; (2) Zn^2+and Ni^2+ enhanced the interaction between PS-ODN and HSA; (3) Upon PS-ODN binding, the conformation of HSA was changed with an increase of β - sheet. Conclusion The results provide experimental evidences to the hypothesis that PS-ODN binds with HSA in the positive potential region, and histidine residues located in the region play a crucial rule in the interaction. 展开更多
关键词 Phosphoruthioate oligodeoxynucleotide Human serum albumin Positive potential region Conformational changes
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Water storage changes in North America retrieved from GRACE gravity and GPS data 被引量:2
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作者 Wang Hansheng Xiang Longwei +4 位作者 Jia Lulu Wu Patrick Steffen Holger Jiang Liming Shen Qiang 《Geodesy and Geodynamics》 2015年第4期267-273,共7页
As global warming continues,the monitoring of changes in terrestrial water storage becomes increasingly important since it plays a critical role in understanding global change and water resource management.In North Am... As global warming continues,the monitoring of changes in terrestrial water storage becomes increasingly important since it plays a critical role in understanding global change and water resource management.In North America as elsewhere in the world,changes in water resources strongly impact agriculture and animal husbandry.From a combination of Gravity Recovery and Climate Experiment(GRACE) gravity and Global Positioning System(GPS) data,it is recently found that water storage from August,2002 to March,2011 recovered after the extreme Canadian Prairies drought between 1999 and 2005.In this paper,we use GRACE monthly gravity data of Release 5 to track the water storage change from August,2002 to June,2014.In Canadian Prairies and the Great Lakes areas,the total water storage is found to have increased during the last decade by a rate of 73.8 ± 14.5 Gt/a,which is larger than that found in the previous study due to the longer time span of GRACE observations used and the reduction of the leakage error.We also find a long term decrease of water storage at a rate of-12.0 ± 4.2 Gt/a in Ungava Peninsula,possibly due to permafrost degradation and less snow accumulation during the winter in the region.In addition,the effect of total mass gain in the surveyed area,on present-day sea level,amounts to-0.18 mm/a,and thus should be taken into account in studies of global sea level change. 展开更多
关键词 Canadian Prairies Great Lakes Ungava Peninsula Water storage changes Gravity Recovery and Climate Experiment (GRACE) data Global positioning System (GPS) data Glacial isostatic adjustment Separation approach
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Dependence of epoch-wise two-way nested ANOVA estimates of variances of unmodeled effects present in relative GPS positioning on satellite elevation cutoff angle and PDOP mask
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作者 Darko Andic Radovan Durovic 《Geodesy and Geodynamics》 CSCD 2022年第5期473-491,共19页
Impact of satellite elevation cutoff angle and position dilution of precision(PDOP)mask change on epoch-wise variance components of unmodeled effects that accompany relative Global Positioning System(GPS)positioning i... Impact of satellite elevation cutoff angle and position dilution of precision(PDOP)mask change on epoch-wise variance components of unmodeled effects that accompany relative Global Positioning System(GPS)positioning is presented herein.Data used for this study refer to the winter and summer periods of the years with minimal(2008)and maximal(2013)solar activity.These data were collected every 30 s in static mode,at two permanent GPS stations located in Montenegro,establishing a mediumdistance(116-km-long)baseline with a height difference of approximately 760 m between its endpoints.The study showed that changing satellite elevation cutoff angle,with a fixed PDOP mask,affects epochwise two-way nested ANOVA estimates of variances related to the‘far-field’multipath(considered as the nested factor herein)and the combined unmodeled effect of tropospheric and ionospheric refraction(considered as the nesting factor herein).However,changing of PDOP mask,with a fixed satellite elevation cutoff angle,doesn’t affect epoch-wise two-way nested ANOVA estimate of variance of the combined unmodeled effect of tropospheric and ionospheric refraction,but,generally,affects the estimate of variance of the‘far-field’multipath(possibly mixed with a part of a‘shorter-term’ionospheric refraction),which is especially pronounced for the summer period.It should also be noted that there is a significant influence of satellite elevation cutoff angle change on both epoch-wise horizontal and vertical position accuracy,only for the summer period,especially in the presence of maximal solar activity,while there is no significant impact of PDOP mask change on epoch-wise positional accuracy. 展开更多
关键词 Unmodeled effects in relative GPS positioning 2-way nested ANOVA Epoch-wise variance components Satellite elevation cutoff angle change PDOP mask change
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