期刊文献+
共找到626篇文章
< 1 2 32 >
每页显示 20 50 100
Cumulative effects of excess high-normal alanine aminotransferase levels in relation to new-onset metabolic dysfunction-associated fatty liver disease in China 被引量:7
1
作者 Jing-Feng Chen Zhuo-Qing Wu +5 位作者 Hao-Shuang Liu Su Yan You-Xiang Wang Miao Xing Xiao-Qin Song Su-Ying Ding 《World Journal of Gastroenterology》 SCIE CAS 2024年第10期1346-1357,共12页
BACKGROUND Within the normal range,elevated alanine aminotransferase(ALT)levels are associated with an increased risk of metabolic dysfunction-associated fatty liver disease(MAFLD).AIM To investigate the associations ... BACKGROUND Within the normal range,elevated alanine aminotransferase(ALT)levels are associated with an increased risk of metabolic dysfunction-associated fatty liver disease(MAFLD).AIM To investigate the associations between repeated high-normal ALT measurements and the risk of new-onset MAFLD prospectively.METHODS A cohort of 3553 participants followed for four consecutive health examinations over 4 years was selected.The incidence rate,cumulative times,and equally and unequally weighted cumulative effects of excess high-normal ALT levels(ehALT)were measured.Cox proportional hazards regression was used to analyse the association between the cumulative effects of ehALT and the risk of new-onset MAFLD.RESULTS A total of 83.13%of participants with MAFLD had normal ALT levels.The incidence rate of MAFLD showed a linear increasing trend in the cumulative ehALT group.Compared with those in the low-normal ALT group,the multivariate adjusted hazard ratios of the equally and unequally weighted cumulative effects of ehALT were 1.651[95%confidence interval(CI):1.199-2.273]and 1.535(95%CI:1.119-2.106)in the third quartile and 1.616(95%CI:1.162-2.246)and 1.580(95%CI:1.155-2.162)in the fourth quartile,respectively.CONCLUSION Most participants with MAFLD had normal ALT levels.Long-term high-normal ALT levels were associated with a cumulative increased risk of new-onset MAFLD. 展开更多
关键词 Metabolic dysfunction-associated fatty liver disease High-normal alanine aminotransferase level cumulative effect Cox proportional hazards regression Cohort study
下载PDF
Study on cumulative effects of biological craniocerebral trauma under repeated blast
2
作者 Xingyuan Huang Bingchen Xia +3 位作者 Lijun Chang Zhikang Liao Hui Zhao Zhihua Cai 《Theoretical & Applied Mechanics Letters》 CAS CSCD 2024年第3期174-183,共10页
Repeated blast impacts on personnel in explosive environments can exacerbate craniocerebral trauma.Most existing studies focus on the injury effects of a single blast,lacking in-depth analysis on the injury effects an... Repeated blast impacts on personnel in explosive environments can exacerbate craniocerebral trauma.Most existing studies focus on the injury effects of a single blast,lacking in-depth analysis on the injury effects and cumulative effects of repeated blasts.Therefore,rats were used as the experimental samples to suffer from explosion blasts with different peak air overpressures(167 kPa~482 kPa)and varying number of repeated blasts.The cumulative effect of craniocerebral trauma was most pronounced for moderate repeated blast,showing approximately 95%increase of trauma severity with penta blast,and an approximately 85%increase of trauma severity with penta minor blast.The cumulative effect of craniocerebral trauma from severe,repeated blast has a smaller rate of change compared to the other two conditions.The severity of trauma from penta blast increased by approximately 69%compared to a single blast.Comprehensive physiological,pathological and biochemical analysis show that the degree of neurological trauma caused by repeated blasts is higher than that of single blasts,and the pathological trauma to brain tissue is more extensive and severe.The trauma degree remains unchanged after double blast,increases by one grade after triple or quadruple blast,and increases by two grades after penta blast. 展开更多
关键词 Repeated blast Craniocerebral trauma Trauma severity grade cumulative effects
下载PDF
Correlation between the cumulative analgesic effect of electroacupuncture intervention and synaptic plasticity of hypothalamic paraventricular nucleus neurons in rats with sciatica 被引量:6
3
作者 Qiuling Xu Tao Liu +4 位作者 Shuping Chen Yonghui Gao Junying Wang Lina Qiao Junling Liu 《Neural Regeneration Research》 SCIE CAS CSCD 2013年第3期218-225,共8页
In the present study, a rat model of chronic neuropathic pain was established by ligation of the sciatic nerve and a model of learning and memory impairment was established by ovariectomy to investigate the analgesic ... In the present study, a rat model of chronic neuropathic pain was established by ligation of the sciatic nerve and a model of learning and memory impairment was established by ovariectomy to investigate the analgesic effect of repeated electroacupuncture stimulation at bilateral Zusanfi (ST36) and Yanglingquan (GB34). In addition, associated synaptic changes in neurons in the paraventricular nucleus of the hypothalamus were examined. Results indicate that the thermal pain threshold (paw withdrawal latency) was significantly increased in rats subjected to 2-week electroacupuncture intervention compared with 2-day electroacupuncture, but the analgesic effect was weakened remarkably in ovariectomized rats with chronic constrictive injury. 2-week electroacupuncture intervention substantially reversed the chronic constrictive injury-induced increase in the synaptic cleft width and thinning of the postsynaptic density. These findings indicate that repeated electroacupuncture at bilateral Zusanfi and Yanglingquan has a cumulative analgesic effect and can effectively relieve chronic neuropathic pain by remodeling the synaptic structure of the hypothalamic paraventricular nucleus. 展开更多
关键词 neural regeneration acupuncture and moxibustion Chronic neuropathic pain electroacupuncture acupuncture analgesia cumulative effect synaptic plasticity HYPOTHALAMUS learning and memory NEUROBIOLOGY grants-supported paper photographs-containing paper neuroregeneration
下载PDF
The cumulative analgesic effect of repeated electroacupuncture involves synaptic remodeling in the hippocampal CA3 region 被引量:5
4
作者 Qiulinq Xu Tao Liu +4 位作者 Shuping Chen Yonghui Gao Junying Wang Lina Qiao Junling Liu 《Neural Regeneration Research》 SCIE CAS CSCD 2012年第18期1378-1385,共8页
In the present study, we examined the analgesic effect of repeated electroacupuncture at bilateral Zusanfi (ST36) and Yanglingquan (GB34) once a day for 14 consecutive days in a rat model of chronic sciatic nerve ... In the present study, we examined the analgesic effect of repeated electroacupuncture at bilateral Zusanfi (ST36) and Yanglingquan (GB34) once a day for 14 consecutive days in a rat model of chronic sciatic nerve constriction injury-induced neuropathic pain. In addition, concomitant changes in calcium/calmodulin-dependent protein kinase II expression and synaptic ultrastructure of neurons in the hippocampal CA3 region were examined. The thermal pain threshold (paw withdrawal latency) was increased significantly in both groups at 2 weeks after electroacupuncture intervention compared with 2 days of electroacupuncture. In ovariectomized rats with chronic constriction injury, the analgesic effect was significantly reduced. Electroacupuncture for 2 weeks significantly diminished the injury-induced increase in synaptJc cleft width and thinning of the postsynaptJc density, and it significantly suppressed the down-regulation of intracellular calcium/ calmodulin-dependent protein kinase II expression in the hippocampal CA3 region. Repeated electroacupuncture intervention had a cumulative analgesic effect on injury-induced neuropathic pain reactions, and it led to synaptic remodeling of hippocampal neurons and upregulated calcium/calmodulin-dependent protein kJnase II expression in the hippocampal CA3 region. 展开更多
关键词 chronic neuropathic pain acupuncture analgesia cumulative effect synaptic plasticity hippocampal CA3 region calcium/calmodulin-dependent protein kinase II NEUROBIOLOGY ELECTROACUPUNCTURE neural regeneration
下载PDF
Seasonal Cumulative Effect of Ural Blocking Episodes on the Frequent Cold events in China during the Early Winter of 2020/21 被引量:9
5
作者 Yao YAO Wenqi ZHANG +2 位作者 Dehai LUO Linhao ZHONG Lin PEI 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2022年第4期609-624,共16页
Starting in mid-November,China was hit by several cold events during the early winter of 2020/21.The lowest temperature observed at Beijing station on 7 January reached−19.6°C.In this paper,we show that the outbr... Starting in mid-November,China was hit by several cold events during the early winter of 2020/21.The lowest temperature observed at Beijing station on 7 January reached−19.6°C.In this paper,we show that the outbreak of the record-breaking extreme cold event can be attributed to a huge merging Ural blocking(UB)ridge over the Eurasian region.The sea-ice cover in the Kara and East Siberia Seas(KESS)in autumn was at its lowest value since 1979,which could have served as a precursor signal.Further analysis shows that several successive UB episodes occurred from 1 September 2020 to 10 January 2021.The persistent UB that occurred in late September/early October 2020 may have made an important contribution to the October historical minimum of sea ice in the KESS region.Our results also show that,after each UB episode in winter,significant upward propagation of wave activity occurred around 60°E,which resulted in weakening the stratospheric vortex.Meanwhile,each UB episode also caused a significant reduction in sea-ice extent in KESS and a significant weakening of the westerly jet in mid-high-latitude Eurasia.Results suggest that the Arctic vortex,which is supposed to enhance seasonally,became weaker and more unstable than the climatic mean under the seasonal cumulative effects of UB episodes,KESS warming,and long-lasting negative-phase North Atlantic Oscillation(NAO-).Those seasonal cumulative effects,combined with the impact of La Niña winter,led to the frequent occurrence of extreme cold events. 展开更多
关键词 extreme cold events Ural blocking Arctic sea ice Arctic vortex cumulative effect
下载PDF
Enhancement effect of cumulative second-harmonic generation by closed propagation feature of circumferential guided waves 被引量:1
6
作者 Guang-Jian Gao Ming-Xi Deng +1 位作者 Ning Hu Yan-Xun Xiang 《Chinese Physics B》 SCIE EI CAS CSCD 2020年第2期301-308,共8页
On the basis of second-order perturbation approximate and modal expansion approach,we investigate the enhancement effect of cumulative second-harmonic generation(SHG)of circumferential guided waves(CGWs)in a circular ... On the basis of second-order perturbation approximate and modal expansion approach,we investigate the enhancement effect of cumulative second-harmonic generation(SHG)of circumferential guided waves(CGWs)in a circular tube,which is inherently induced by the closed propagation feature of CGWs.An appropriate mode pair of primary-and double-frequency CGWs satisfying the phase velocity matching and nonzero energy flux is selected to ensure that the second harmonic generated by primary CGW propagation can accumulate along the circumference.Using a coherent superposition of multi-waves,a model of unidirectional CGW propagation is established for analyzing the enhancement effect of cumulative SHG of primary CGW mode selected.The theoretical analyses and numerical simulations performed directly demonstrate that the second harmonic generated does have a cumulative effect along the circumferential direction and the closed propagation feature of CGWs does enhance the magnitude of cumulative second harmonic generated.Potential applications of the enhancement effect of cumulative SHG of CGWs are considered and discussed.The theoretical analysis and numerical simulation perspective presented here yield an insight previously unavailable into the physical mechanism of the enhancement effect of cumulative SHG by closed propagation feature of CGWs in a circular tube. 展开更多
关键词 CIRCUMFERENTIAL guided wave second-harmonic generation(SHG) enhancement effect of cumulative SHG CLOSED PROPAGATION FEATURE
下载PDF
The Impact of Meteorological Factors on the Short-term Cumulative Effect of Air Particulate in Tianjin 被引量:1
7
作者 Wang Wei Liu Lili Wang Yan 《Meteorological and Environmental Research》 CAS 2019年第2期27-32,40,共7页
In order to reveal the rapid increase mechanism of particulate concentration in short time,a notion of short-term cumulative effect of air particulate is defined as the significant increase of pollutant concentration ... In order to reveal the rapid increase mechanism of particulate concentration in short time,a notion of short-term cumulative effect of air particulate is defined as the significant increase of pollutant concentration in a short time under the condition of breeze,stable weather and constant emission caused by human being's activities. Subsequently,an index of short-term cumulative effect is established with air diffusive equation,and then the macro-scale meteorological situation and micro-scale factors of forming the short-term cumulative effect are discussed with the observation data. The macro-scale meteorological variables contain upper-level weather situations and surface weather situations. The micro-scale factors mainly include the boundary-layer height and boundary-layer stability. The analyses show that boundary-layer factors and weather variables have a significant influence on the short-term cumulative effect. The notion of short-term cumulative effect will play an important role in interpreting the severe pollution weather. 展开更多
关键词 AIR PARTICULATE SHORT-TERM cumulative effect METEOROLOGICAL factor cumulative index
下载PDF
Blasting cumulative damage effects of underground engineering rock mass based on sonic wave measurement 被引量:5
8
作者 闫长斌 《Journal of Central South University of Technology》 EI 2007年第2期230-235,共6页
The principle of sonic wave measurement was introduced, and cumulative damage effects of underground engineering rock mass under blasting load were studied by in situ test, using RSM-SY5 intelligent sonic wave apparat... The principle of sonic wave measurement was introduced, and cumulative damage effects of underground engineering rock mass under blasting load were studied by in situ test, using RSM-SY5 intelligent sonic wave apparatus. The blasting test was carried out for ten times at some tunnels of Changba Lead-Zinc Mine. The damage depth of surrounding rock caused by old blasting excavation (0.8-1.2 m) was confirmed. The relation between the cumulative damage degree and blast times was obtained. The results show that the sonic velocity decreases gradually with increasing blast times, hut the damage degree (D) increases. The damage cumulative law is non-linear. The damage degree caused by blast decreases with increasing distance, and damage effects become indistinct. The blasting damage of rock mass is anisotropic. The damage degree of rock mass within charging range is maximal. And the more the charge is, the more severe the damage degree of rock mass is. The test results provide references for researches of mechanical parameters of rock mass and dynamic stability analysis of underground chambers. 展开更多
关键词 sonic wave measurement cumulative damage effects damage degree blasting load surrounding rock of underground engineering RSM-SY5 intelligent sonic wave apparatus
下载PDF
Quantitative Evaluation of Ecological Cumulative Effects and Zoning Regulations for Prefectural Mining Units in China
9
作者 MA Li KANG Lei +1 位作者 TIAN Huazheng XU Die 《Chinese Geographical Science》 SCIE CSCD 2022年第1期49-63,共15页
Although the development of energy and mineral resources strongly supports China’s rapid industrialization and urbanization,it has led to a series of ecological and environmental problems.Strengthening the spatial re... Although the development of energy and mineral resources strongly supports China’s rapid industrialization and urbanization,it has led to a series of ecological and environmental problems.Strengthening the spatial regulation considering the ecological and environmental protection on energy and mineral resource development areas is an important aspect of realizing China’s sustainable development.In this study,we mapped,categorized,and analyzed the ecological cumulative effects of the Chinese 134 prefectural mining units based on the pressure-state-response model,which is demonstrated as impact of mining activities on ecological environment,ecological environmental fragility,and ecological function.This investigation developed a stress zoning typology of the mining units based on scores of three dimensions of the ecological cumulative effects and classified 134 prefectural mining units into eight types of stress zones.A series of regulation and policy suggestions have been proposed to different types of zones from three aspects:space control,intensity control,and development mode control.The application of this evaluation and spatial zoning system will contribute to the refined spatial management of China’s mining areas. 展开更多
关键词 ecological cumulative effects quantitative evaluation pressure-state-response model ZONING
下载PDF
Cumulative impact of dam constructions on streamflow and sediment regime in lower reaches of the Jinsha River, China 被引量:7
10
作者 HUANG Xiao-rong GAO Lin-yun +1 位作者 YANG Peng-peng XI Yuan-yuan 《Journal of Mountain Science》 SCIE CSCD 2018年第12期2752-2765,共14页
The cumulative effect of cascade hydropower stations on river ecological environment has been widely concerned because of the significant streamflow hydrology change induced by dam constructions. The characteristics o... The cumulative effect of cascade hydropower stations on river ecological environment has been widely concerned because of the significant streamflow hydrology change induced by dam constructions. The characteristics of the change in the lower reaches of the Jinsha River, China are analyzed based on long-term(1952–2015) hydrological and sedimentological data. The averaging coefficient, reservoir regulation coefficient(RRC), incoming sediment coefficient(ISC), and sediment transport modulus(STM), which reflect the variation of streamflow and sediment regimes, are defined and calculated. The results show that the construction and regulation of reservoirs reduces flow in flood season, increases flow in dry season, significantly altering the monthly discharge regimes. These alterations also led directly to changes in the timing of extreme flows at Pingshan Station. The monthly flow records at the basin outlet are reconstructed using stepwise regression, to reduce reservoir impacts. Comparisons of observed and reconstructed monthly flows demonstrate that the previous studies overestimated the cumulative effects of cascade reservoirs on flow processes. Furthermore, this study clearly illustrates that the reduction in sediment trapping and sediment transportation capacity together lead to the sharp reduction in annual sediment yield at the Pingshan Station. The earlier constructed reservoirs have more obvious effects on the ISC and STM than the more recent reservoirs and the effect of sediment trapping is related to reservoir location, on the main stream versus tributaries. 展开更多
关键词 CASCADE RESERVOIRS cumulative effect HYDROLOGICAL REGIME Sediment load Jinsha River
下载PDF
Cumulative second-harmonic generation of Lamb waves propagating in a two-layered solid plate 被引量:2
11
作者 项延训 邓明晰 《Chinese Physics B》 SCIE EI CAS CSCD 2008年第11期4232-4241,共10页
The physical process of cumulative second-harmonic generation of Lamb waves propagating in a two-layered solid plate is presented by using the second-order perturbation and the technique of nonlinear reflection of aco... The physical process of cumulative second-harmonic generation of Lamb waves propagating in a two-layered solid plate is presented by using the second-order perturbation and the technique of nonlinear reflection of acoustic waves at an interface. In general, the cumulative second-harmonic generation of a dispersive guided wave propagation does not occur. However, the present paper shows that the second-harmonic of Lamb wave propagation arising from the nonlinear interaction of the partial bulk acoustic waves and the restriction of the three boundaries of the solid plates does have a cumulative growth effect if some conditions are satisfied. Through boundary condition and initial condition of excitation, the analytical expression of cumulative second-harmonic of Lamb waves propagation is determined. Numerical results show the cumulative effect of Lamb waves on second-harmonic field patterns. 展开更多
关键词 Lamb waves second harmonics cumulative effect layered plates
下载PDF
Cumulative radiation exposure from diagnostic imaging in intensive care unit patients
12
作者 Fiachra Moloney Daniel Fama +7 位作者 Maria Twomey Ruth O'Leary Conor Houlihane Kevin P Murphy Siobhan B O'Neill Owen J O'Connor Dorothy Breen Michael M Maher 《World Journal of Radiology》 CAS 2016年第4期419-427,共9页
AIM:To quantify cumulative effective dose of intensive care unit(ICU)patients attributable to diagnostic imaging.METHODS:This was a prospective,interdisciplinary study conducted in the ICU of a large tertiary referral... AIM:To quantify cumulative effective dose of intensive care unit(ICU)patients attributable to diagnostic imaging.METHODS:This was a prospective,interdisciplinary study conducted in the ICU of a large tertiary referral and level 1 trauma center.Demographic and clinical data including age,gender,date of ICU admission,primary reason for ICU admission,APACHE Ⅱ score,length of stay,number of days intubated,date of death or discharge,and re-admission data was collected on all patients admitted over a 1-year period.The overall radiation exposure was quantified by the cumulative effective radiation dose(CED)in millisieverts(mS v)and calculated using reference effective doses published by the United Kingdom National Radiation Protection Board.Pediatric patients were selected for subgroupanalysis.RESULTS:A total of 2737 studies were performedin 421 patients.The total CED was 1704 m Sv with a median CED of 1.5 mS v(IQR 0.04-6.6 mS v).Total CED in pediatric patients was 74.6 mS v with a median CED of 0.07 mS v(IQR 0.01-4.7 mS v).Chest radiography was the most commonly performed examination accounting for 83% of all studies but only 2.7% of total CED.Computed tomography(CT)accounted for 16% of all studies performed and contributed 97% of total CED.Trauma patients received a statistically significant higher dose [median CED 7.7 mS v(IQR 3.5-13.8 mS v)] than medical [median CED 1.4 m Sv(IQR 0.05-5.4 m Sv)] and surgical [median CED 1.6 mS v(IQR 0.04-7.5 mS v)] patients.Length of stay in ICU [OR = 1.12(95%CI:1.079-1.157)] was identified as an independent predictor of receiving a CED greater than 15 mS v.CONCLUSION:Trauma patients and patients with extended ICU admission times are at increased risk of higher CEDs.CED should be minimized where feasible,especially in young patients. 展开更多
关键词 cumulative effective DOSE PEDIATRIC PATIENTS COMPUTED tomography Radiation DOSE INTENSIVE care unit
下载PDF
Experimental investigation of the cyclic degradation of the one-way shape memory effect of NiTi alloys
13
作者 Tian-xing Zhao Guo-zheng Kang +1 位作者 Chao Yu Qian-hua Kan 《International Journal of Minerals,Metallurgy and Materials》 SCIE EI CAS CSCD 2019年第12期1539-1550,共12页
Based on stress-and strain-controlled cyclic tension-unloading-heat-cooling tests,cyclic degradation of the one-way shape memory effect(OWSME)of NiTi shape memory alloys(SMAs)was investigated.It was seen,in thermo-mec... Based on stress-and strain-controlled cyclic tension-unloading-heat-cooling tests,cyclic degradation of the one-way shape memory effect(OWSME)of NiTi shape memory alloys(SMAs)was investigated.It was seen,in thermo-mechanical coupled cyclic tests,that residual strain after each cycle accumulated,but the martensite reorientation stress and dissipation energy-per-cycle decreased as the number of cycles increased.Meanwhile,the cyclic degradation of OWSME was aggravated by increasing the stress/strain amplitude.In addition,the stress-strain response of NiTi SMAs was further investigated by performing simultaneous thermo-mechanical coupled cyclic tests with various phase-angle differences between the mechanical and thermal cyclic loadings.It can be concluded that such cyclic response depends significantly on prescribed phase-angle differences.Obtained experimental results are helpful for both the development of constitutive models and engineering applications of NiTi SMAs. 展开更多
关键词 NITI SHAPE MEMORY alloys one-way SHAPE MEMORY effect CYCLIC degradation THERMO-MECHANICAL coupling MARTENSITE orientation
下载PDF
Shaking table test and cumulative deformation evaluation analysis of a tunnel across the hauling sliding surface
14
作者 Lifang Pai Honggang Wu Xu Wang 《Deep Underground Science and Engineering》 2023年第4期371-393,共23页
To explore the cumulative deformation effect of the dynamic response of a tunnel crossing the hauling sliding surface under earthquakes,the shaking table test was conducted in this study.Combined with the numerical ca... To explore the cumulative deformation effect of the dynamic response of a tunnel crossing the hauling sliding surface under earthquakes,the shaking table test was conducted in this study.Combined with the numerical calculations,this study proposed magnification of the Arias intensity(MIa)to characterize the overall local deformation damage of the tunnel lining in terms of the deformation characteristics,frequency domain,and energy.Using the time‐domain analysis method,the plastic effect coefficient(PEC)was proposed to characterize the degree of plastic deformation,and the applicability of the seismic cumulative failure effect(SCFE)was discussed.The results show that the low‐frequency component(f1 and f2≤10 Hz)and the high‐frequency component(f3 and f4>10 Hz)acceleration mainly cause global and local deformation of the tunnel lining.The local deformation caused by the high‐frequency wave has an important effect on the seismic damage of the lining.The physical meaning of PEC is more clearly defined than that of the residual strain,and the SCFE of the tunnel lining can also be defined.The SCFE of the tunnel lining includes the elastic deformation effect stage(<0.15g),the elastic–plastic deformation effect stage(0.15g–0.30g),and the plastic deformation effect stage(0.30g–0.40g).This study can provide valuable theoretical and technical support for the construction of traffic tunnels in high‐intensity earthquake areas. 展开更多
关键词 magnification of Arias intensity plastic effect coefficient seismic action seismic cumulative failure effect shaking table test tunnel engineering
下载PDF
Ecological risk assessment and early warning of heavy metal cumulation in the soils near the Luanchuan molybdenum polymetallic mine concentration area,Henan Province,central China 被引量:13
15
作者 Zhen-yu Chen Yuan-yi Zhao +3 位作者 Dan-li Chen Hai-tao Huang Yu Zhao Yu-jing Wu 《China Geology》 CAS CSCD 2023年第1期15-26,共12页
The Luanchuan molybdenum polymetallic mine concentration area is rich in mineral resources and has a long history of mining.The environmental impact of long-term mining activities cannot be ignored.It is of great sign... The Luanchuan molybdenum polymetallic mine concentration area is rich in mineral resources and has a long history of mining.The environmental impact of long-term mining activities cannot be ignored.It is of great significance to study the ecological risk and the accumulation trends of heavy metals in the soil of mining areas for scientific prevention and control of heavy metal pollution.Taking the Taowanbeigou River Basin in the mine concentration area as the research object,the ecological pollution risk and cumulative effect of heavy metals in the soil of the basin were studied by using the comprehensive pollution index method,potential ecological risk assessment method and geoaccumulation index method.On this basis,the cumulative exceeding years of specific heavy metals were predicted by using the early warning model.The comprehensive potential ecological risk of heavy metals in the soil near the Luanchuan mine concentration area is moderate,and the single element Cd is the main ecological risk factor,with a contribution rate of 53.6%.The overall cumulative degrees of Cu and Pb in the soil are“none-moderate”,Zn and Cd are moderate,Mo has reached an extremely strong cumulative level,Hg,As and Cr risks are not obvious,and the overall cumulative risks order is Mo>Cd>Zn>Cu>Pb>Hg.According to the current accumulation rate and taking the risk screening values for soil contamination of agricultural land as the reference standard,the locations over standard rates of Cu,Zn and Cd will exceed 78%in 90years,and the over standard rate of Pb will reach approximately 57%in 200 years.The cumulative exceeding standard periods of As,Cr and Hg are generally long,which basically indicates that these elements do not pose a significant potential threat to the ecological environment.Mining activities will accelerate the accumulation of heavy metals in soil.With the continuous development of mining activities,the potential pollution risk of heavy metals in the soil of mining areas will also increase. 展开更多
关键词 Soil Heavy metals Mining impact cumulative effect Potential ecological risk cumulation early warning Luanchuan mine concentration area Environmental geological survey engineering
下载PDF
Acupuncture effects on the hippocampal cholinergic system in a rat model of neuropathic pain 被引量:4
16
作者 Junying Wang Junling Liu Shuping Chen Yonghui Gao Fanying Meng Lina Qiao 《Neural Regeneration Research》 SCIE CAS CSCD 2012年第3期212-218,共7页
The present study observed the effects of repeated electroacupuncture of Zusanli (ST36) and Yanglingquan (GB34) on expression of hippocampal acetylcholinesterase, vesicular acetylcholine transporter, and muscarini... The present study observed the effects of repeated electroacupuncture of Zusanli (ST36) and Yanglingquan (GB34) on expression of hippocampal acetylcholinesterase, vesicular acetylcholine transporter, and muscarinic M1 receptor mRNA in chronic constrictive injury (neuropathic pain) and/or ovariotomy rats. Results demonstrated increased expression of hippocampal acetylcholinesterase, vesicular acetylcholine transporter, and muscarinic M1 receptor mRNA, as well as decreased pain threshold, in a rat model of chronic neuropathic pain after electroacupuncture. The effects of electroacupuncture increased with prolonged time, but the above-mentioned effects decreased in memory-deficient animals. Results indicated that repeated electroacupuncture has a cumulative analgesic effect, which is closely associated with upregulation of acetylcholinesterase and vesicular acetylcholine transporter activity, as well as M1 receptor mRNA expression and memory. 展开更多
关键词 ACETYLCHOLINESTERASE chronic pain cumulative effect electroacupuncture analgesia HIPPOCAMPUS M1R mRNA expression vesicular acetylcholine transporter
下载PDF
Utilizing a new soil effective temperature scheme and archived satellite microwave brightness temperature data to estimate surface soil moisture in the Nagqu region, Tibetan Plateau of China 被引量:1
17
作者 TIAN Hui Mudassar IQBAL 《Journal of Arid Land》 SCIE CSCD 2018年第1期84-100,共17页
Since the early 2000s, many satellite passive microwave brightness temperature (BT) archives, such as the Advanced Microwave Scanning Radiometer for the Earth Observing System (AMSR-E) BTs, have become the useful ... Since the early 2000s, many satellite passive microwave brightness temperature (BT) archives, such as the Advanced Microwave Scanning Radiometer for the Earth Observing System (AMSR-E) BTs, have become the useful resources for assessing the changes in the surface and deep soil moistures over both arid and semi-arid regions. In this study, we used a new soil effective temperature (T scheme and the archived AMSR-E BTs to estimate surface soil moisture (SM) over the Nagqu region in the central Tibetan Plateau, China. The surface and deep soil temperatures required for the calculation of regional-scale T were obtained from outputs of the Community Land Model version 4.5 (CLM4.5). In situ SM measurements at the CEOP-CAMP/Tibet (Coordinated Enhanced Observing Period Asia-Australia Monsoon Project on the Tibetan Plateau) experimental sites were used to validate the AMSR-E-based SM estimations at regional and single-site scales. Furthermore, the spatial distribution of monthly mean surface SM over the Nagqu region was obtained from 16 daytime AMSR-E BT observations in July 2004 over the Nagqu region. Results revealed that the AMSR-E-based surface SM estimations agreed well with the in situ-based surface SM measurements, with the root mean square error (RMSE) ranging from 0.042 to 0.066 m3/m3 and the coefficient of determination (R2) ranging from 0.71 to 0.92 during the nighttime and daytime. The regional surface soil water state map showed a clear spatial pattern related to the terrain. It indicated that the lower surface SM values occurred in the mountainous areas of the northern, mid-western and southeastern parts of Nagqu region, while the higher surface SM values appeared in the low elevation areas such as the Tongtian River Basin, Namco Lake and bog meadows in the central part of Nagqu region. Our analysis also showed that the new T^scheme does not require special fitting parameters or additional assumptions, which simplifies the data requirements for regional-scale applications. This scheme combined with the archived satellite passive microwave BT observations can be used to estimate the historical surface SM for hydrological process studies over the Tibetan Plateau regions. 展开更多
关键词 soil effective temperature archived AMSR-E brightness temperature CLM4.5 soil temperature output cumulative Distribution Function (CDF) matching surface soil moisture Tibetan Plateau
下载PDF
Anaerobic biodegradability of terephthalic acid and its inhibitory effect on anaerobic digestion 被引量:3
18
作者 Kuang Xin Wang Jusi(Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China) 《Journal of Environmental Sciences》 SCIE EI CAS CSCD 1994年第2期180-188,共9页
The behavior of terephthalic acid (TPA) in anaerobic system has been studied bysemicontinuous bioassays under mesophilic condition with artificial TPA production wastewater. Theeffect of different loading rate of TPA ... The behavior of terephthalic acid (TPA) in anaerobic system has been studied bysemicontinuous bioassays under mesophilic condition with artificial TPA production wastewater. Theeffect of different loading rate of TPA on anaerobic digestion was studied under certain CODloading rate. The results showed that the TPA could be degraded anaerobically within a relativelylow range. The degradable concentration of TPA was less than 500 mg/L in the digester, higherconcentration of TPA could not be degraded totally and the rate of degradation might decrease withthe increase of feed amount. The inhibition is related to both loading rate and accumulatedconcentration of TPA in the digesters. 展开更多
关键词 anaerobic biodegradability terephthalic acid inhibitory effect semi-continuous bioassay ac-cumulated concentration .
下载PDF
Empirical Analysis of the Market Effects of China's Listed—— Company's Dividend Policy ——Empirical Evidences from Shanghai Stock Exchange from 2004 to 2005
19
作者 Shufeng Li Di Liu 《Journal of Modern Accounting and Auditing》 2006年第4期10-21,共12页
Dividend policy is one of the three core contents of financial management in listed companies. On one hand, it is the extension of financial and investment activities; on the other hand, appropriate dividend policy ca... Dividend policy is one of the three core contents of financial management in listed companies. On one hand, it is the extension of financial and investment activities; on the other hand, appropriate dividend policy can not only set up a good company reputation, but also arouse enthusiasm of many investors to continue invest in this company, consequently acquire long and stable development opportunities and conditions. In this paper, the author has put forward some suggestions in order to solve the problems which existing in Chinese listed companies' dividend policies based on the result of positive test. Firstly, optimize the structure of equity title and perfect the corporate governance. Secondly, to establish wholesome shareholder protection mechanism, and also it is important measure for investors, especially medium and small investors to protect their rights and interests. According to the present situation of Chinese stock market, the authors consider we can protect the shareholder's benefits by carrying out cumulative vote system, establishing hortative derive lawsuit system, perfecting civil compensation system and establishing shareholder voting removing system and so on. Thirdly, the establishment of listed companies' dividend policy and the release of message should be standardized for the sake of good relationship of melon-cutting and corporation's refinancing plan. Finally, listed companies' dividend policy can be optimized by modifying and perfecting stock dividend distribution mode of accounting management, perfecting exit mechanism of listed companies. 展开更多
关键词 dividend policy market effect cumulative abnormal return
下载PDF
家庭风险因素对青少年自伤的累积效应及其性别差异 被引量:1
20
作者 王玉龙 赵婧斐 蔺秀云 《心理发展与教育》 CSSCI 北大核心 2024年第2期240-247,共8页
以累积风险模型为基础,以453名初一学生为被试进行间隔10个月的追踪研究,考察家庭风险因素对青少年当前和10个月后自伤行为的累积效应及其性别差异。结果表明:(1)家庭风险因素对青少年当前和10个月后的自伤均有明显的累积效应,且均以线... 以累积风险模型为基础,以453名初一学生为被试进行间隔10个月的追踪研究,考察家庭风险因素对青少年当前和10个月后自伤行为的累积效应及其性别差异。结果表明:(1)家庭风险因素对青少年当前和10个月后的自伤均有明显的累积效应,且均以线性模式发挥作用;(2)在累积家庭风险与青少年当前自伤之间的线性关系中有明显的性别差异,女生有更高的家庭累积风险,且女生的自伤更容易受家庭累积风险的影响。 展开更多
关键词 青少年 自伤 家庭风险因素 性别差异 累积效应
下载PDF
上一页 1 2 32 下一页 到第
使用帮助 返回顶部