期刊文献+
共找到76,162篇文章
< 1 2 250 >
每页显示 20 50 100
Natural Tourism in Kosovo and the Potentials of the Dukagjin Region
1
作者 Alberta Tahiri Anela Džogović +13 位作者 Idriz Kovaçi Thëllëza Latifi Sadrija Nora Draga Elvira Misini Ardiana Hyseni Selvije Lajqi Doresa Mulaj Fatbardha Shala Hyrije Bajramaj Kushtrim Agaj Flaka Muriqi Mimoza Mekuli Ismet Berisha Mendim Nimonaj 《Journal of Environmental & Earth Sciences》 2025年第3期274-285,共12页
This study aims to assess the potential of natural tourism in Kosovo,especially in the Dukagjin region as a case study.The main objective is to identify and analyze this region’s tourism potential to understand its i... This study aims to assess the potential of natural tourism in Kosovo,especially in the Dukagjin region as a case study.The main objective is to identify and analyze this region’s tourism potential to understand its impact and importance.180 respondents from the Dukagjin region participated in this study,and the quantitative method was used as a methodology.The measurement instrument consisted of 30 closed questions,which aimed to collect detailed information on the potential of natural tourism in this area.The study results showed that mountain,cultural,winter,healing,and rural tourism are especially important for developing the Dukagjin region.Furthermore,the analysis shows that 30%of the tourism potential is explained by rural tourism,underlining its importance in the local economy.Finally,the study’s findings are discussed,emphasizing their practical value for promoting and developing sustainable tourism in the region. 展开更多
关键词 Development Dukagjin Region Natural Tourism Rural Tourism Tourist potentials Tourism Promotion
在线阅读 下载PDF
Delocalized Nonlinear Vibrational Modes in Bcc Lattice for Testing and Improving Interatomic Potentials
2
作者 Denis S.Ryabov IgorV.Kosarev +2 位作者 Daxing Xiong Aleksey A.Kudreyko Sergey V.Dmitriev 《Computers, Materials & Continua》 2025年第3期3797-3820,共24页
Molecular dynamics(MD)is a powerful method widely used in materials science and solid-state physics.The accuracy of MD simulations depends on the quality of the interatomic potentials.In this work,a special class of e... Molecular dynamics(MD)is a powerful method widely used in materials science and solid-state physics.The accuracy of MD simulations depends on the quality of the interatomic potentials.In this work,a special class of exact solutions to the equations of motion of atoms in a body-centered cubic(bcc)lattice is analyzed.These solutions take the form of delocalized nonlinear vibrational modes(DNVMs)and can serve as an excellent test of the accuracy of the interatomic potentials used in MD modeling for bcc crystals.The accuracy of the potentials can be checked by comparing the frequency response of DNVMs calculated using this or that interatomic potential with that calculated using the more accurate ab initio approach.DNVMs can also be used to train new,more accurate machine learning potentials for bcc metals.To address the above issues,it is important to analyze the properties of DNVMs,which is the main goal of this work.Considering only the point symmetry groups of the bcc lattice,34 DNVMs are found.Since interatomic potentials are not used in finding DNVMs,they are exact solutions for any type of potential.Here,the simplest interatomic potentials with cubic anharmonicity are used to simplify the analysis and to obtain some analytical results.For example,the dispersion relations for small-amplitude phonon modes are derived,taking into account interactions between up to the fourth nearest neighbor.The frequency response of the DNVMs is calculated numerically,and for some DNVMs examples of analytical analysis are given.The energy stored by the interatomic bonds of different lengths is calculated,which is important for testing interatomic potentials.The pros and cons of using DNVMs to test and improve interatomic potentials for metals are discussed.Since DNVMs are the natural vibrational modes of bcc crystals,any reliable interatomic potential must reproduce their properties with reasonable accuracy. 展开更多
关键词 Interatomic potentials molecular dynamics bcc lattice long-range interactions dispersion relation nonlinear dynamics exact solution delocalized nonlinear vibrational mode
在线阅读 下载PDF
Event-related potentials reveal hypnotherapy's impact on attention bias in social anxiety disorder
3
作者 Han Zhang Mi Zhang +8 位作者 Ni Li Wen-Zhuo Wei Lin-Xi Yang Yong-Yi Li Zhen-Yue Zu Li-Jun Ma Hui-Xue Wang Kai Wang Xiao-Ming Li 《World Journal of Psychiatry》 2025年第5期241-256,共16页
BACKGROUND Exploring hypnotherapy's potential to modulate attention bias offers promising avenues for treating social anxiety disorder(SAD).AIM To determine if hypnotherapy can alleviate social anxiety by influenc... BACKGROUND Exploring hypnotherapy's potential to modulate attention bias offers promising avenues for treating social anxiety disorder(SAD).AIM To determine if hypnotherapy can alleviate social anxiety by influencing attention bias,specifically identifying the aspects of attention processes affected by hypnosis.METHODS In this study,69 SAD participants were divided into three groups based on their Liebowitz Social Anxiety Scale scores:Experimental group,control group,and baseline group.The experimental group(n=23)underwent six weekly hypnosis sessions,while the control(n=23)and baseline groups(n=23)received no treatment.To evaluate alterations in SAD severity and attention bias towards threatening stimuli following hypnotherapy,we employed a combination of self-report questionnaires,an odd-one-out task,and electroencephalography recordings.RESULTS The experimental group showed significant reductions in P1,N170,N2pc,and late positive potential(LPP)brain wave activities during attention sensitivity and disengagement conditions.This indicates that hypnotherapy modulates early-stage face processing and later-stage emotional evaluation of threat-related stimuli in SAD patients.CONCLUSION Our findings highlight P1,N170,N2pc,and LPP as key neural markers in SAD treatment.By identifying these neural markers influenced by hypnotherapy,we offer insight into the mechanisms by which this treatment modality impacts attentional processes,potentially easing SAD symptoms. 展开更多
关键词 Social anxiety disorder Attention bias HYPNOTHERAPY Event-related potentials Face processing
暂未订购
A comprehensive review of meal replacement from dining table to sickbed:beyond biomedical potentials
4
作者 Hao Qiang Tianshu Xu +4 位作者 Peng Ma Siyuan Zhang Guanhua Du Guifen Qiang Tengfei Ji 《Food Science and Human Wellness》 2025年第3期822-834,共13页
The emergence of meal replacement(MR)originates from physical exercise or fitness as a substitute for one or all meals and later expands to the field of weight loss.Indeed,the main application of current meal replacem... The emergence of meal replacement(MR)originates from physical exercise or fitness as a substitute for one or all meals and later expands to the field of weight loss.Indeed,the main application of current meal replacement is to lose body weight,whether patients with obesity,diabetes,fatty liver,infertile or pregnant women can benefit from weight loss.In addition,MRs still exhibit more biomedical potential in preventing and treating diseases,like anti-diabetes,improving fatty liver and kidney disease,preventing cancer,conceiving and reducing pregnancy complications,and improving life quality.Indeed,there are also disadvantages to meal replacement,including causing adverse effects,although most are acceptable and tolerated.To date,various commercially-developed MRs are walking from dining table to sickbed.Therefore,a scientific understanding of the advantages and disadvantages of meal replacements is crucial for their extensive application beyond biomedical potentials. 展开更多
关键词 Meal replacement Weight loss Biomedical potentials
在线阅读 下载PDF
Three-component soliton states in spinor F=1 Bose-Einstein condensates with PT-symmetric generalized Scarf-Ⅱpotentials
5
作者 Zhang-Lei Han Jun-Yi Lao +1 位作者 Jia-Rui Zhang Yu-Jia Shen 《Communications in Theoretical Physics》 2025年第4期1-11,共11页
Introducing PT-symmetric generalized Scarf-Ⅱpotentials into the three-coupled nonlinear Gross-Pitaevskii equations offers a new way to seek stable soliton states in quasi-onedimensional spin-1 Bose-Einstein condensat... Introducing PT-symmetric generalized Scarf-Ⅱpotentials into the three-coupled nonlinear Gross-Pitaevskii equations offers a new way to seek stable soliton states in quasi-onedimensional spin-1 Bose-Einstein condensates.In scenarios where the spin-independent parameter c_(0)and the spin-dependent parameter c_(2)vary,we use both analytical and numerical methods to investigate the three-coupled nonlinear Gross-Pitaevskii equations with PT-symmetric generalized Scarf-Ⅱpotentials.We obtain analytical soliton states and find that simply modulating c_(2)may change the analytical soliton states from unstable to stable.Additionally,we obtain numerically stable double-hump soliton states propagating in the form of periodic oscillations,exhibiting distinct behavior in energy exchange.For further investigation,we discuss the interaction of numerical double-hump solitons with Gaussian solitons and observe the transfer of energy among the three components.These findings may contribute to a deeper understanding of solitons in Bose-Einstein condensates with PT-symmetric potentials and may hold significance for both theoretical understanding and experimental design in related physics experiments. 展开更多
关键词 three-component soliton states PT-symmetric generalized Scarf-Ⅱpotentials Bose-Einstein condensates Three-coupled nonlinear Gross-Pitaevskii equations
原文传递
Effective nucleus-nucleus potentials for heavy-ion fusion reactions
6
作者 Ning Wang Jin-Ming Chen Min Liu 《Nuclear Science and Techniques》 2025年第2期103-111,共9页
Based on the Skyrme energy density functional and reaction Q-value,this study proposed an effective nucleus-nucleus poten-tial for describing the capture barrier in heavy-ion fusion processes.The 443 extracted barrier... Based on the Skyrme energy density functional and reaction Q-value,this study proposed an effective nucleus-nucleus poten-tial for describing the capture barrier in heavy-ion fusion processes.The 443 extracted barrier heights were well reproduced with a root-mean-square(RMS)error of 1.53 MeV,and the RMS deviations with respect to 144 time-dependent Hartree-Fock capture barrier heights were only 1.05 MeV.Coupled with the Siwek-Wilczyński formula,wherein three parameters were determined by the proposed effective potentials,the measured capture cross sections at energies around the barriers were reasonably well reproduced for several fusion reactions induced by nearly spherical nuclei as well as by nuclei with large deformations,such as^(154)Sm and^(238)U.The shallow capture pockets and small values of the average barrier radii resulted in the reduction of the capture cross sections for 52,54Cr-and 64 Ni-induced reactions,which were related to the synthesis of new super-heavy nuclei. 展开更多
关键词 Nucleus-nucleus potential Fusion reactions Superheavy nuclei Capture cross sections
在线阅读 下载PDF
An in-depth study of spin-and momentum-dependent interaction potentials between two spin-1/2 fermions mediated by light spin-0 particles
7
作者 Yang Zhong Zhi-Hui Guo Hai-Qing Zhou 《Communications in Theoretical Physics》 2025年第8期82-93,共12页
We present a calculation by including the relativistic and off-shell contributions to the interaction potentials between two spin-1/2 fermions mediated by the exchange of light spin-0 particles,in both momentum and co... We present a calculation by including the relativistic and off-shell contributions to the interaction potentials between two spin-1/2 fermions mediated by the exchange of light spin-0 particles,in both momentum and coordinate spaces.Our calculation is based on the four-point Green's function rather than the scattering amplitude.Among the sixteen potential components,eight that vanish in the non-relativistic limit are shown to acquire nonzero relativistic and off-shell corrections.In addition to providing relativistic and off-shell corrections to the operator basis commonly used in the literature,we introduce an alternative operator basis that facilitates the derivation of interaction potentials in the coordinate space.Furthermore,we calculate both the long-range and short-range components of the potentials,which can be useful for future experimental analyses at both macroscopic and atomic scales. 展开更多
关键词 AXION potential relativistic correction
原文传递
Quantum-mechanical understanding on structure dependence of image potentials of single-walled boron nitride nanotubes
8
作者 Yu Zhang Zhiman Zhang +2 位作者 Weiliang Wang Shaolin Zhang Haiming Huang 《Chinese Physics B》 SCIE EI CAS CSCD 2024年第12期467-475,共9页
The recent discovery of field emission devices based on one-dimensional nanostructures has attracted much interest in emerging applications on next-generation flat panel displays,molecule-based sensors,and so forth.To... The recent discovery of field emission devices based on one-dimensional nanostructures has attracted much interest in emerging applications on next-generation flat panel displays,molecule-based sensors,and so forth.To achieve a comprehensive understanding of surface potentials at the nano-emitters during the tunneling process,in this study we systematically investigated the image potentials of single-walled boron nitride nanotubes with different edges,diameters and lengths in the frame of a composite first-principles calculation.The image potentials of zigzag single-walled boron nitride nanotubes are found to be dependent on the non-equivalent sides.Only the image potentials of isolated armchair single-walled boron nitride nanotube can be well fitted with the image potential of an ideal metal sphere of a size comparable to the tube diameter.On the contrary,the image potentials of zigzag and grounded armchair single-walled boron nitride nanotubes exhibit a strong length-dependence characteristic and are significantly different from that of an ideal metal sphere,which originates from the significant axial symmetry breaking of induced charge at the tip for the long tube.The correlation between the testing electron and electronic structure of single-walled boron nitride nanotube has also been discussed. 展开更多
关键词 boron nitride nanotubes quantum chemistry image potentials structure dependence
原文传递
Thermal conductivity of GeTe crystals based on machine learning potentials
9
作者 张健 张昊春 +1 位作者 李伟峰 张刚 《Chinese Physics B》 SCIE EI CAS CSCD 2024年第4期104-107,共4页
GeTe has attracted extensive research interest for thermoelectric applications.In this paper,we first train a neuroevolution potential(NEP)based on a dataset constructed by ab initio molecular dynamics,with the Gaussi... GeTe has attracted extensive research interest for thermoelectric applications.In this paper,we first train a neuroevolution potential(NEP)based on a dataset constructed by ab initio molecular dynamics,with the Gaussian approximation potential(GAP)as a reference.The phonon density of states is then calculated by two machine learning potentials and compared with density functional theory results,with the GAP potential having higher accuracy.Next,the thermal conductivity of a GeTe crystal at 300 K is calculated by the equilibrium molecular dynamics method using both machine learning potentials,and both of them are in good agreement with the experimental results;however,the calculation speed when using the NEP potential is about 500 times faster than when using the GAP potential.Finally,the lattice thermal conductivity in the range of 300 K-600 K is calculated using the NEP potential.The lattice thermal conductivity decreases as the temperature increases due to the phonon anharmonic effect.This study provides a theoretical tool for the study of the thermal conductivity of GeTe. 展开更多
关键词 machine learning potentials thermal conductivity molecular dynamics
原文传递
Tetrathiafulvalene esters with high redox potentials and improved solubilities for non-aqueous redox flow battery applications
10
作者 Weikang Hu Jiaqi Xu +3 位作者 Nanjie Chen Zongcai Deng Yuekun Lai Dongyang Chen 《Green Energy & Environment》 SCIE EI CAS CSCD 2024年第5期899-908,共10页
The exploitation of high performance redox-active substances is critically important for the development of non-aqueous redoxflow batteries.Herein,three tetrathiofulvalene(TTF)derivatives with different substitution gr... The exploitation of high performance redox-active substances is critically important for the development of non-aqueous redoxflow batteries.Herein,three tetrathiofulvalene(TTF)derivatives with different substitution groups,namely TTF diethyl ester(TTFDE),TTF tetramethyl ester(TTFTM),and TTF tetraethyl ester(TTFTE),are prepared and their energy storage properties are evaluated.It has been found that the redox potential and solubility of these TTF derivatives in conventional carbonate electrolytes increases with the number of ester groups.The battery with a catholyte of 0.2 mol L^(-1) of TTFTE delivers a specific capacity of more than 10 Ah L^(-1) at the current density of 0.5 C with two discharge voltage platforms locating at as high as 3.85 and 3.60 V vs.Li/Liþ.Its capacity retention can be improved from 2.34 Ah L^(-1) to 3.60 Ah L^(-1) after 100 cycles by the use of an anion exchange membrane to block the crossover of TTF species.The excellent cycling stability of the TIF esters is supported by their well-delocalized electrons,as revealed by the density function theory calculations.Therefore,the introduction of more and larger electron-withdrawing groups is a promising strategy to simultaneously increase the redox-potential and solubility of redox-active ma-terials for non-aqueous redoxflow batteries. 展开更多
关键词 Non-aqueous redox flow batteries Tetrathiofulvarene Redox potential SOLUBILITY Substituent effect
在线阅读 下载PDF
A robust method for evaluating the potentials of 15-minute cities:Implications for sustainable urban futures
11
作者 Jianying Wang Mei-Po Kwan +1 位作者 Gezhi Xiu Fangxu Deng 《Geography and Sustainability》 CSCD 2024年第4期597-606,共10页
The‘15-minute city’(15minC)concept,which aspires to bring essential services within reach via a 15-minute walk for all residents,represents a pivotal paradigm shift in sustainable urban development.However,the achie... The‘15-minute city’(15minC)concept,which aspires to bring essential services within reach via a 15-minute walk for all residents,represents a pivotal paradigm shift in sustainable urban development.However,the achievability of this concept for different cities varies considerably across diverse population distributions,urban contexts,and development priorities.In this study,we propose a robust method for evaluating a city’s 15minC potential-a city’s capability to achieve widespread 15-minute accessibility while maintaining an optimal balance between resource efficiency and resident accessibility.We employ the Location Set Covering Problem optimization model to analyze the resources required to achieve full coverage of 15-minute accessibility and the knee point detection algorithm to assess a city’s 15minC potential.Across 23 major Chinese cities,our method exhibits a sharp sensitivity to delineate distinct 15minC potentials.It reveals that cities’current 15minC development level doesn’t align with their inherent potential uniformly.Key determinants include how well current facility locations match population centers and the population density in remote areas.Further,reducing facility constructions by twothirds has only a marginal impact on accessibility,emphasizing the need for tailored,data-driven planning in effective and sustainable urban development based on the distinct potentials of cities.Our approach prioritizes resource efficiency,minimizing the inefficient use of facilities that serve only a small portion of residents while maximizing the benefits of the 15minC and therefore has significant implications for a sustainable urban future. 展开更多
关键词 15-Minute city Development potential SUSTAINABILITY Efficiency
在线阅读 下载PDF
Masseter Vestibular evoked myogenic potentials: A new tool to assess the vestibulomasseteric reflex pathway
12
作者 Aishwarya Nagarajan Sujeet Kumar Sinha 《Journal of Otology》 CAS CSCD 2024年第1期46-54,共9页
Purpose: This review article provides the readers with an in-depth insight in understanding and interpreting various research literatures on the masseter vestibular evoked myogenic potentials(mVEMP). The article also ... Purpose: This review article provides the readers with an in-depth insight in understanding and interpreting various research literatures on the masseter vestibular evoked myogenic potentials(mVEMP). The article also reviews the contemporary researches involving the clinical applications of the mVEMP. Conclusions: Masseter VEMP is an evolving yet clinically promising neuro-otology test tool that has recently gained more research interest and is considered an additional tool to diagnose various vestibular disorders. Masseter VEMP assesses the functional integrity of the acoustic-masseteric and vestibulo-masseteric reflex pathways. The mVEMP could be used as a complementary test to evaluate the same peripheral generator as the cervical VEMP but a different central pathway i.e., vestibulo-trigeminal pathway. Various research studies that have experimented on parameters such as the effect of different electrode montages(zygomatic vs mandibular configurations), stimulation rates, filter settings and stimuli used to evoke mVEMP have been discussed in this article that could assist in the optimization of a comprehensive clinical protocol. The latency and the amplitude of mVEMP waveforms serve as significant parameters in differentiating normals from those of the clinical populations. Along with the cVEMPs and oVEMPs, mVEMP might help diagnose brainstem lesions in REM Sleep behaviour disorders, Multiple Sclerosis and Parkinson's disease. However, further studies are required to probe in this area of research. 展开更多
关键词 Masseter vestibular evoked myogenic potentials(mVEMP) Vestibulo-masseteric pathway Acoustic-masseteric pathway
暂未订购
Game theory based finite-time formation control using artificial potentials for tethered space net robot
13
作者 Yifeng MA Yizhai ZHANG +2 位作者 Panfeng HUANG Ya LIU Fan ZHANG 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2024年第8期358-372,共15页
The Tethered Space Net Robot(TSNR)is an innovative solution for active space debris capture and removal.Its large envelope and simple capture method make it an attractive option for this task.However,capturing maneuve... The Tethered Space Net Robot(TSNR)is an innovative solution for active space debris capture and removal.Its large envelope and simple capture method make it an attractive option for this task.However,capturing maneuverable debris with the flexible and elastic underactuated net poses significant challenges.To address this,a novel formation control method for the TSNR is proposed through the integration of differential game theory and robust adaptive control in this paper.Specifically,the trajectory of the TSNR is obtained through the solution of a real-time feedback pursuit-evasion game with a dynamic target,where the primary condition is to ensure the stability of the TSNR.Furthermore,to minimize tracking errors and maintain a specific configuration,a robust adaptive formation control scheme with Artificial Potential Field(APF)based on a Finite-Time Convergent Extended State Observer(FTCESO)is investigated.The proposed control method has a key advantage in suppressing complex oscillations by a new adaptive law,thus precisely maintaining the configuration.Finally,numerical simulations are performed to demonstrate the effectiveness of the proposed scheme. 展开更多
关键词 Game theory Formation control Artificial potential field Relative distance constraint Tethered space net robot(TSNR)
原文传递
Clinical characteristics and analysis of vestibular-evoked myogenic potentials in patients with sudden sensorineural hearing loss in different ages
14
作者 Yan-Zhuo Zhang Ya-Bo Wang +6 位作者 Jing-Lei Fang Yue-Tang Wang Gui-Fang Li Ran-Ran Liu Shu-Jing Shi Chun-Hua Wang Yong-Tao Tian 《World Journal of Clinical Cases》 SCIE 2024年第19期3760-3766,共7页
BACKGROUND Numerous studies have found that patients experiencing sudden sensorineural hearing loss(SSHL),with or without accompanying vertigo,often show impaired vestibular function.However,there is a dearth of studi... BACKGROUND Numerous studies have found that patients experiencing sudden sensorineural hearing loss(SSHL),with or without accompanying vertigo,often show impaired vestibular function.However,there is a dearth of studies analyzing vestibularevoked myogenic potentials(VEMPs)in SSHL patients across various age groups.AIM To investigate vestibular condition in SSHL patients across various age demographics.METHODS Clinical data of 84 SSHL patients were investigated retrospectively.Audiometry,cervical vestibular evoked myogenic potentials(c-VEMPs),and ocular vestibular evoked myogenic potentials(o-VEMPs)were conducted on these patients.Parameters assessed included the latencies of P1 and N1 waves,as well as the amplitudes of P1–N1 waves.Moreover,the study evaluated the influence of factors such as sex,affected side,configuration of hearing loss,and presence of accompanying vertigo.RESULTS Among the 84 SSHL patients,no significant differences were observed among the three groups in terms of gender,affected side,and the presence or absence of vertigo.Group II(aged 41–60 years)had the highest number of SSHL cases.The rates of absent o-VEMPs in the affected ears were 20.83%,31.58%,and 22.72%for the three age groups,respectively,with no statistically significant difference among them.The rates of absent c-VEMPs in the affected ears were 8.3%,34.21%,and 18.18%for the three age groups,respectively,with significant differences.In the unaffected ears,there were differences observed in the extraction rates of o-VEMPs in the unaffected ears among the age groups.In the three age groups,no significant differences were noted in the three age groups in the latencies of P1 and N1 waves or in the amplitude of N1–P1 waves for c-VEMPs and o-VEMPs,either on the affected side or on the unaffected side,across the three age groups.CONCLUSION The extraction rate of VEMPs is more valuable than parameters.Regardless of the presence of vertigo,vestibular organs are involved in SSHL.Notably,SSHL patients aged 41–60 appear more susceptible to damage to the inferior vestibular nerve and saccule. 展开更多
关键词 Sudden sensorineural hearing loss Cervical vestibular evoked myogenic potential Ocular vestibular evoked myogenic potential VERTIGO Pure tone audiometry
暂未订购
The Aharonov-Bohm Effect: An Exploration of Quantum Interference and Electromagnetic Potentials
15
作者 Bahman Zohuri 《Journal of Energy and Power Engineering》 CAS 2024年第3期79-87,共9页
The AB(Aharonov-Bohm)effect is a pivotal quantum mechanical phenomenon that illustrates the fundamental role of the electromagnetic vector potential A in determining the phase of a charged particle’s wave function,ev... The AB(Aharonov-Bohm)effect is a pivotal quantum mechanical phenomenon that illustrates the fundamental role of the electromagnetic vector potential A in determining the phase of a charged particle’s wave function,even in regions where the magnetic field B is zero.This effect demonstrates that quantum particles are influenced not only by the fields directly present but also by the potentials associated with those fields.In the AB effect,an electron beam is split into two paths,with one path encircling a solenoid and the other bypassing it.Despite the absence of a magnetic field in the regions traversed by the beams,the vector potential A associated with the magnetic flux Φ through the solenoid induces a phase shift in the electron’s wave function.This phase shift,quantified by △φ=qΦ/hc,manifests as a change in the interference pattern observed in the detection screen.The phenomenon underscores the principle of gauge invariance in QED(quantum electrodynamics),where physical observables remain invariant under local gauge transformations of the vector and scalar potentials.This reinforces the notion that the vector potential A has a profound impact on quantum systems,beyond its classical role.This article outlines the AB effect,including its theoretical framework,experimental observations,and implications.The focus on the role of the vector potential in quantum mechanics provides a comprehensive understanding of this important phenomenon. 展开更多
关键词 AB effect vector potential(A) magnetic flux(Φ) quantum phase shift gauge invariance electromagnetic potentials interference pattern scalar fields longitudinal waves QED
在线阅读 下载PDF
Mass Increase with Strong and Gravitational Potentials, and Mass Defect with Electromagnetic Potential
16
作者 Hany Ali Hussein 《Journal of High Energy Physics, Gravitation and Cosmology》 CAS 2024年第3期1079-1094,共16页
The proposal is “mass increases due to strong and gravitational potentials, while it decreases due to Electromagnetic potential”. This proposal explains the big difference in mass between hadrons (protons, neutrons,... The proposal is “mass increases due to strong and gravitational potentials, while it decreases due to Electromagnetic potential”. This proposal explains the big difference in mass between hadrons (protons, neutrons, & mesons) and their components (quarks), mass difference between nucleus and its individual components (protons and neutrons), massless of gamma photons, abnormal masses of mesons and bosons, and the excess in galaxy masses (dark matter). Also, this proposal shows the exact relation between mass and energy: Strong Potential=−3.04mc2| Electric Potential |=−5.57×10−3mc2Gravitational Potential=−1.22×10−7mc2where m represents the excess in mass due to strong potential, or gravitational potential and represents the decrease in mass due to electromagnetic potential. Released energy here equals potential energy and doesn’t equal decrease in mass using the formula E = mc2. Released energy is transferred to heat, photons, kinetic energy… Finally, proposal will try to describe the relation between photon energy and mass of its components using the general equation of kinetic energy: Photon Energy=1/2mc2m is the sum of the individual masses of its components, while the total mass of photon is zero. 展开更多
关键词 Mass Defect Dark Matter PHOTON Gamma Photon Strong Potential Gravitational Potential Electromagnetic Potential QUARKS Mesons BOSONS Deuterium Proton Neutron
在线阅读 下载PDF
Median Nerve Somatosensory Evoked Potentials in Patients with Chiari Malformation
17
作者 Mustafa Harun Sahin Gonul Vural +1 位作者 Serdar Barakli Sadiye Gumusyayla 《World Journal of Neuroscience》 CAS 2024年第1期24-32,共9页
Abnormal SEP reflects dysfunction of the medial lemniscus and posterior cervical cord. These structures are likely to be affected in Chiari malformation. Therefore, SEP abnormalities may provide valuable information i... Abnormal SEP reflects dysfunction of the medial lemniscus and posterior cervical cord. These structures are likely to be affected in Chiari malformation. Therefore, SEP abnormalities may provide valuable information in patients with CM. However, the consistency of SEP abnormality or normality with the damage is a matter of research. Knowing whether median nerve somatosensory evoked potential (SEP) is useful in revealing subclinical damage in patients with Chiari malformation is important in the treatment and follow-up plan of the disease. The aim of this study was to investigate the relationship between median nerve SEP values and the severity of cerebellar ectopia in patients with Chiari type 1 malformation. Median nerve SEP values were obtained from 30 healthy individuals and 146 individuals with Chiari malformation. The cerebellar ectopia degree and McRae line length were measured. SEP values were not significantly different between groups. The McRae line was found to be significantly shorter in the control group than in the Chiari malformation group (p = 0.031). There was no correlation between the degree of cerebellar ectopia and the length of the McRae line (r = 0.002, p = 0.979). Neither cerebellar ectopy degree nor McRae line length had a relationship with SEP values (r = -0.153, p = 0.066;r = -0.056, p = 0.500, respectively). There was no difference in cerebellar ectopy degree or SEP values between the groups with cerebellar ectopy with and without a syrinx (p = 0.899;p = 0.080, respectively). Likewise, McRae line length was not found to be related to the presence of a syrinx (p = 0.139). Median nerve SEP examination was not beneficial for diagnosing asymptomatic-oligosymptomatic Chiari malformation as a subclinical injury, whether accompanied by syringomyelia or not. 展开更多
关键词 Chiari Malformation Cerebellar Ectopy Somatosensory Evoked Potential
暂未订购
Entrepreneurship training:its influences on innovation potentials among nursing students
18
作者 Asmaa Abdel Rahman Abdel Rahman Dalia Abdallah Abdelatief 《Frontiers of Nursing》 2024年第1期85-98,共14页
Objective:To evaluate the influences of entrepreneurship training on the innovation potential among nursing students.Methods:A quasi-experimental design was utilized to conduct this study.The study was conducted in th... Objective:To evaluate the influences of entrepreneurship training on the innovation potential among nursing students.Methods:A quasi-experimental design was utilized to conduct this study.The study was conducted in the classroom at the faculty of nursing,and the“i Hub”center at Ain Shams University(ASU)in Cairo,Egypt.A purposive sample of 42 nursing students who participated in the“Ain Shams University-innovate”competition from the Faculty of Nursing of ASU were included in this study.Data collection tools included(1)Nursing students'innovation skills assessment questionnaire and(2)Innovative projects evaluation tool.Results:There was a statistically significant difference between the mean scores of nursing students'total innovation skills pre-and post-implementation of entrepreneurship training,where P-value<0.05.Conclusions:The results of the current study support the research hypothesis because the implementation of entrepreneurship training positively affects nursing students'innovation potential.Developing entrepreneurship education in nursing and integrating it into nursing programs will stimulate creativity,innovation,and entrepreneurship among nursing students and health care services. 展开更多
关键词 entrepreneurship training innovation potentials nursing students creative skills energy/motivation
在线阅读 下载PDF
中国镍钴矿产资源禀赋条件与找矿潜力 被引量:6
19
作者 张照伟 吴华英 +3 位作者 谭文娟 王亚磊 邵继 李文渊 《岩石学报》 北大核心 2025年第2期416-430,共15页
镍、钴属于新能源金属,在高端制造业、合金材料、新能源电池等领域具有不可替代性,需求量逐年陡增。但国内镍钴矿产资源原料极度短缺,对外依存度已高达93%和99%,潜在资源安全威胁凸显,加强国内镍钴矿产资源勘查已迫在眉睫。本文系统分... 镍、钴属于新能源金属,在高端制造业、合金材料、新能源电池等领域具有不可替代性,需求量逐年陡增。但国内镍钴矿产资源原料极度短缺,对外依存度已高达93%和99%,潜在资源安全威胁凸显,加强国内镍钴矿产资源勘查已迫在眉睫。本文系统分析了我国镍钴矿产资源成矿特征,无论是成矿类型,还是构造背景特征,与全球均存在显著不同。全球60%的镍资源主要赋存于红土型镍钴矿床中,40%的镍资源则储存在岩浆镍钴硫化物矿床内,而我国镍资源的93%赋存在岩浆镍钴硫化物矿床中。世界上60%的钴资源来自沉积型铜钴矿床、23%的岩浆型镍钴矿床、15%的红土型镍钴矿床及2%的热液型含钴矿床,而我国钴资源45%赋存于岩浆镍钴硫化物矿床内、40%的钴资源赋存在与热液相关矿床中,受赋存状态及开发利用条件限制,这部分赋存在热液矿床中的钴资源尚不能有效利用。可见,我国镍钴资源关键来源是岩浆型镍钴矿床。对比我国岩浆镍钴硫化物矿床成矿特征及地质分布特点,本文提出我国岩浆镍钴硫化物矿床独特的资源禀赋条件,重要结合带旁侧滞后发育的铁质系列镁铁-超镁铁质侵入岩是镍钴资源赋存的关键空间,明确勘查工作的重点方向。另外,分析认为,加强钴矿赋存状态研究,创新破解开发利用条件限制,是实现钴资源增储上产的关键路径。这为指导镍钴资源勘查、助力找矿新突破提供了重要依据。 展开更多
关键词 镁铁-超镁铁质岩 镍钴矿床 资源禀赋 找矿潜力 勘查空间
在线阅读 下载PDF
森林土壤储碳与增汇的不确定性分析 被引量:2
20
作者 王晖 刘世荣 +2 位作者 周正虎 陈亮 王健 《生态学报》 北大核心 2025年第8期3626-3644,共19页
森林具有类型多样、结构复杂以及随环境变化等特征,1 m深森林土壤储存的碳约占全球森林生态系统总碳储量的45%,约占全球土壤碳库的52%。目前对森林土壤固碳潜力和关键过程机制的认识还十分有限。因此,森林土壤储碳与增汇的估算仍存在很... 森林具有类型多样、结构复杂以及随环境变化等特征,1 m深森林土壤储存的碳约占全球森林生态系统总碳储量的45%,约占全球土壤碳库的52%。目前对森林土壤固碳潜力和关键过程机制的认识还十分有限。因此,森林土壤储碳与增汇的估算仍存在很大不确定性。研究梳理了森林土壤有机碳(SOC)储量、密度、含量、增量、固定和碳汇等术语定义;综述了SOC稳定性的机制,包括化学结构稳定性、团聚体物理保护、金属氧化物和粘土矿物吸附,生物与环境主导有机碳稳定固持,以及最新研究相继提出的森林SOC组分多样性及功能复杂性维持碳稳定的学术观点。研究还分析了森林SOC储量和增量不同测定方法的主要原理、优点和不足。根据已有文献数据分析,全球森林1 m深SOC储量变化范围为383—787 Pg C(Pg=10^(15)g),年变化范围为每年降低349 Tg C(Tg=10^(12)g)到每年增加498 Tg C。中国森林1 m深SOC储量评估范围为16.0—34.2 Pg C,年变化范围为每年降低64.5 Tg C到增加217.3 Tg C。说明目前对森林SOC储量和增量的估算还存在很大不确定性。最新研究表明全球森林碳容量和固碳潜力巨大,但不同研究对SOC是否存在上限仍具不同观点,气候变化对森林SOC储量及其持续固碳潜力的影响也存在较大的不确定性。未来建议通过学科交叉深入探索森林群落结构与土壤固碳过程之间的联系,从碳组分多样性和功能复杂性的新视角理解森林SOC的形成与稳定机制;将SOC监测纳入国家森林资源清查体系、建立国家尺度的SOC长期监测网络、设立我国森林SOC增汇大科学计划;提出保持SOC稳定固持的天然林保护修复及经营提升途径;建立培育高固碳树种,优化林分结构,合理采伐以及轮伐期延长等人工林土壤固碳增汇经营技术体系。 展开更多
关键词 森林土壤 储碳 增汇 固碳潜力 不确定性
在线阅读 下载PDF
上一页 1 2 250 下一页 到第
使用帮助 返回顶部