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Quantifying the natural growth rate of hepatocellular carcinoma:A real-world retrospective study in southwestern China
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作者 Li Tu Hong Xie +6 位作者 Qi Li Ping-Gui Lei Pei-Ling Zhao Fan Yang Chi Gong Yuan-Lin Yao Shi Zhou 《World Journal of Hepatology》 2024年第5期800-808,共9页
BACKGROUND In recent years,approximately half of the newly diagnosed cases and mortalities attributed to hepatocellular carcinoma(HCC)have been reported in China.Despite the high incidence of HCC,there remains a pauci... BACKGROUND In recent years,approximately half of the newly diagnosed cases and mortalities attributed to hepatocellular carcinoma(HCC)have been reported in China.Despite the high incidence of HCC,there remains a paucity of data regarding the natural growth pattern and the determination of optimal surveillance intervals specific to the Chinese population.AIM To quantify the natural tumor growth pattern of HCC in regional China.METHODS A retrospective analysis was performed on patients from a single institution in Southwest China who had undergone two or more serial dynamic computed tomography or magnetic resonance imaging scans between 2014 and 2020,without having received any anti-cancer therapy.Tumor growth was assessed using tumor volume doubling time(TVDT)and tumor growth rate(TGR),with volumes measured manually by experienced radiologists.Simple univariate linear regression and descriptive analysis were applied to explore associations between growth rates and clinical factors.RESULTS This study identifies the median TVDT for HCC as 163.4 d,interquartile range(IQR)72.1 to 302.3 d,with a daily TGR of 0.42%(IQR 0.206%-0.97%).HCC growth patterns reveal that about one-third of tumors grow indolently with TVDT exceeding 270 d,another one-third of tumors exhibit rapid growth with TVDT under 90 d,and the remaining tumors show intermediate growth rates,with TVDT ranging between 3 to 9 months.CONCLUSION The identified TGRs support biannual surveillance and follow-up for HCC patients in certain regions of China.Given the observed heterogeneity in HCC growth,further investigation is warranted. 展开更多
关键词 Hepatocellular carcinoma natural tumor growth pattern Tumor volume doubling time Tumor growth rate Realworld retrospective study
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A study of hydrate plug formation in a subsea natural gas pipeline using a novel high-pressure flow loop 被引量:11
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作者 Li Wenqing Gong Jing +3 位作者 Lü Xiaofang Zhao Jiankui Feng Yaorong Yu Da 《Petroleum Science》 SCIE CAS CSCD 2013年第1期97-105,共9页
The natural gas pipeline from Platform QKI8-1 in the southwest of Bohai Bay to the onshore processing facility is a subsea wet gas pipeline exposed to high pressure and low temperature for a long distance. Blockages i... The natural gas pipeline from Platform QKI8-1 in the southwest of Bohai Bay to the onshore processing facility is a subsea wet gas pipeline exposed to high pressure and low temperature for a long distance. Blockages in the pipeline occur occasionally. To maintain the natural gas flow in the pipeline, we proposed a method for analyzing blockages and ascribed them to the hydrate formation and agglomeration. A new high-pressure flow loop was developed to investigate hydrate plug formation and hydrate particle size, using a mixture of diesel oil, water, and natural gas as experimental fluids. The influences of pressure and initial flow rate were also studied. Experimental results indicated that when the flow rate was below 850 kg/h, gas hydrates would form and then plug the pipeline, even at a low water content (10%) of a water/oil emulsion. Furthermore, some practical suggestions were made for daily management of the subsea pipeline. 展开更多
关键词 natural gas hydrate BLOCKAGE flow assurance high-pressure loop water cut flow rate
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Effects of acupuncture treatment on natural killer cell activity,pulse rate,and pain reduction for older adults:an uncontrolled,observational study 被引量:9
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作者 Hidetoshi Mori Hiroshi Kuge +3 位作者 Tim Hideaki Tanaka Eiichi Taniwaki Kazuyo Hanyu Tateyuki Morisawa 《Journal of Integrative Medicine》 SCIE CAS CSCD 2013年第2期101-105,共5页
OBJECTIVE: The aim of this study was to examine the changes in natural killer (NK) cell activity, pulse rate, and pain intensity among older adults before and after acupuncture treatment. METHODS: Fifty-six indivi... OBJECTIVE: The aim of this study was to examine the changes in natural killer (NK) cell activity, pulse rate, and pain intensity among older adults before and after acupuncture treatment. METHODS: Fifty-six individuals (16 males and 40 females), aged 60 to 82 years (mean age 72.4 + 5.0), who were experiencing pain in the shoulder, low back, or knee, participated in the study. NK cell activity, leukocyte differentiation (granulocytes and lymphocytes), pulse rate, and blood pressure values were obtained. Pain intensity was evaluated by using the visual analog scale (VAS). The Wilcoxon test was used to analyze NK cell activity, leukocytes (granulocyte counts and granulocyte-to-lymphocyte ratio), and the VAS score in accordance with the location of pain complaints before and after acupuncture treatment. RESULTS: NK cell activity decreased after acupuncture treatment for pain in the shoulder-pain and knee-pain groups. Further, the lymphocyte and granulocyte counts increased after acupuncture treatment for the shoulder-pain group. Pulse rate decreased for the shoulder-pain, low-back- pain, and knee-pain groups after acupuncture treatment. The VAS score decreased after acupuncture treatment for the shoulder-pain, low-back-pain, and knee-pain groups. CONCLUSION: This study showed that in older adults, acupuncture treatment decreases pulse rate, relieves pain in the shoulder, low back, and knee, and reduces NK-cell activity. 展开更多
关键词 acupuncture therapy killer cells natural leukocytes heart rate pain measurement clinical trial
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RECENT ADVANCES IN HYDRATE-BASED TECHNOLOGIES FOR NATURAL GAS STORAGE——A REVIEW 被引量:27
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作者 Yasuhiko H.Mori 《化工学报》 EI CAS CSCD 北大核心 2003年第z1期1-17,共17页
Interest in the possibility of storing and transporting natural gas in the form of clathrate hydrates has been increasing in recent years, particularly in some gas-importing and exporting countries.The technologies ne... Interest in the possibility of storing and transporting natural gas in the form of clathrate hydrates has been increasing in recent years, particularly in some gas-importing and exporting countries.The technologies necessary for realizing this possibility may be classified into those relevant to the four serial processes (a) the formation of a hydrate, (b) the processing (dewatering, pelletizing, etc. ) of the formed hydrate, (c) the storage and transportation of the processed hydrate, and (d) the regasification (dissociation) of the hydrate. The technological development of any of these processes is still at an early stage. For hydrate formation, for example, various rival operations have been proposed. However,many of them have never been subjected to actual tests for practical use. More efforts are required for examining the different hydrate-formation technologies and for rating them by comparison. The general design of the processing of the formed hydrate inevitably depends on both the hydrate-formation process and the storage/transportation process, hence it has a wide variability. The major uncertainty in the storage-process design lies in the as-yet unclarified utility of the "self-preservation" effect of the naturalgas hydrates. The process design as well as the relevant cost evaluation should strongly depend on whether the hydrates are well preserved at atmospheric pressure in large-scale storage facilities. The regasification process has been studied less extensively than the former processes. The state of the art of the technological development in each of the serial processes is reviewed, placing emphasis on the hydrate formation process. 展开更多
关键词 into rate or AS of that RECENT ADVANCES IN HYDrate-BASED TECHNOLOGIES FOR natural GAS STORAGE A REVIEW been
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Experimental Study on Preparation of Natural Gas Hydrate by Crystallization 被引量:7
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作者 Ma Shihui Pan Zhen +4 位作者 Li Ping Wu Yuguo Li Bingfan Kang Jinke Zhang Zhien 《China Petroleum Processing & Petrochemical Technology》 SCIE CAS 2017年第1期106-113,共8页
In this paper, the saturated solution crystallization method is proposed to promote the formation of hydrate by means of the known similarities between the hydrate formation process and the crystallization process. In... In this paper, the saturated solution crystallization method is proposed to promote the formation of hydrate by means of the known similarities between the hydrate formation process and the crystallization process. In this method,adding the second phase crystals was used to replace the spontaneous formation of hydrate crystal nuclei to form hydrate.The effects of saturated Na_2SO_4, MgSO_4, NH_4HCO_3 and CuSO_4 solutions on the formation rates of natural gas hydrate and gas storage capacity were investigated. The results showed that the saturated solution had an influence on the hydrate formation process. Under the given experimental conditions, the saturated Na_2SO_4 solution showed a highest increase in the hydrate formation rate, and the average hydrate formation rate in its presence was 11.8 times higher than that obtained in the deionized water. Moreover, the largest formation rate of gas hydrates observed in the saturated Na_2SO_4 solution was 386 times bigger than that in the deionized water, and the gas storage capacity increased by 10 times. In addition, the average hydrate formation rate in the saturated Mg SO_4 solution was faster than that in water by 20 times. The largest formation rate of gas hydrates in the saturated MgSO_4 solution was 165 times faster than that obtained in the deionized water, and the gas storage capacity increased by 6.2 times. The saturated NH_4HCO_3 and saturated CuSO_4 solutions also influenced the formation process of hydrate. Therefore, the crystallization method of saturated solution can be used to achieve a highefficiency preparation of natural gas hydrates, which provides theoretical guidance for the storage of natural gas in the form of hydrate. 展开更多
关键词 natural gas hydrate saturated solution crystal seeds formation rate gas storage capacity phase equilibrium
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Energy spectrum measurement and dose rate estimation of natural neutrons in Tibet region 被引量:1
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作者 吴建华 徐勇军 +1 位作者 刘森林 汪传高 《Nuclear Science and Techniques》 SCIE CAS CSCD 2015年第6期25-28,共4页
In this work, natural neutron spectra at nine sites in Tibet region were measured using a multi-sphere neutron spectrometer. The altitude-dependence of the spectra total fluence rate and ambient dose equivalent rate w... In this work, natural neutron spectra at nine sites in Tibet region were measured using a multi-sphere neutron spectrometer. The altitude-dependence of the spectra total fluence rate and ambient dose equivalent rate were analyzed. From the normalized natural neutron spectra at different altitudes, the spectrum fractions for neutrons of greater than 0.1 MeV do not differ obviously, while those of the thermal neutrons differ greatly from each other. The total fluence rate, effective dose rate and the ambient dose equivalent rate varied with the altitude according to an exponential law. 展开更多
关键词 中子能谱测量 西藏地区 剂量率 剂量当量率 估算 天然 能量密度 高度变化
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Stochastic Optimal Economic Growth Model with Natural Resources
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作者 ZHOU Shaobo HU Shigeng WANG Maofa 《Wuhan University Journal of Natural Sciences》 EI CAS 2006年第3期511-514,共4页
The paper examines an economic growth problem how social planners reasonably open up and retain natural resources. The objective is to maximize the total expected discounted utility of comsumption. Social planners' o... The paper examines an economic growth problem how social planners reasonably open up and retain natural resources. The objective is to maximize the total expected discounted utility of comsumption. Social planners' optimal decision and optimal expected rates at the steady state are derived. At last, how productivity and productivity shock affect on the expected growth rate, consumption-resources ratio and the fraction of exploited resources, are analyzed. 展开更多
关键词 natural resources optimal portfolio expected growth rate
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A New Method to Predict Erythrocyte Sedimentation Rate with Natural Geographical Factors and Location by Case-based Reasoning: A Case Study of China
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作者 YANG Qingsheng YOU Xibin +3 位作者 ZHANG Hongxian Kevin MWENDA WANG Yuandong HUANG Ying 《Chinese Geographical Science》 SCIE CSCD 2020年第1期157-169,共13页
Reference values of erythrocyte sedimentation rate(ESR)are the key to interpret ESR blood test in clinic.The common local reference ESR values are more accuracy in blood test that are established with natural geograph... Reference values of erythrocyte sedimentation rate(ESR)are the key to interpret ESR blood test in clinic.The common local reference ESR values are more accuracy in blood test that are established with natural geographical factors by using the multiple linear regression(MLR)model and the artificial neural network(ANN).These knowledge-based methods have limitations since the knowledge domains of ESR and natural geographical factors are limited.This paper presents a new cases-depended model to establish reference ESR values with natural geographical factors and location using case-based reasoning(CBR)since knowledge domain of ESR and geographical factors is weak.Overall 224 local normal ESR values of China that calculated from 13623 samples were obtained,and the corresponding natural geographical factors and location that include altitude,sunshine hours,relative humidity,temperature,precipitation,annual temperature range and annual average wind speed were obtained from the National Geomatics Center of China.CBR was used to predict the unseen local reference ESR values with cases.The average absolute deviation(AAD),mean square error(MSE),prediction accuracy(PA),and Pearson correlation coefficient(r)between the observed and estimated data of proposed model is 33.07%,9.02,66.93% and 0.78,which are better than those of ANN and MLR model.The results show that the proposed model provides higher prediction accuracy than those of the artificial neural network and multiple linear regression models.The predicted values are very close to the observed values.Model results show significant agreement of cases data.Consequently,the model is used to predict the unseen local reference ESR with natural geographical factors and location.In spatial,the highest ESR reference areas are distributed in the southern-western district of China that includes Sichuan,Chongqing,Guangxi and Guizhou provinces,and the reference ESR values are greater than 23 mm/60 min.The higher ESR reference values are distributed in the middle part and northern-eastern of China which include Hubei,Henan,Shaanxi,Shanxi,Jilin and Heilongjiang provinces,and the reference ESR values are greater than 18 mm/60min.The lowest ESR reference values are distributed in the northern-western of China that includes Tibet and Xinjiang,and the reference ESR values are lower than 5 mm/60min. 展开更多
关键词 erythrocyte sedimentation rate(ESR) natural geographical factors case-based reasoning(CBR) China
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Is It Wrong to Apply the Intrinsic Rate of Natural Increase to Individuals and Compare It among Genotypes?
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作者 Takahiro Miyo 《Open Journal of Genetics》 2018年第1期1-13,共13页
In order to gain insights into the seasonal dynamics of genetic variation in insecticide resistance within a natural population of Drosophila melanogaster during population growth, which we considered the most importa... In order to gain insights into the seasonal dynamics of genetic variation in insecticide resistance within a natural population of Drosophila melanogaster during population growth, which we considered the most important ecological factor there, we conducted a series of genetic analyses of resistance factors involved in that population and compared individual-based intrinsic rates of natural increase among resistance genotypes. However, some researchers have argued that it is a misconception to apply the intrinsic rate of natural increase to individuals, because it is a population parameter. We consider that their criticisms were incorrect. In this article, I described our research briefly and set forth the reasons why we conducted these studies. 展开更多
关键词 Drosophila MELANOGASTER INSECTICIDE Resistance Intrinsic rate of natural Increase natural Population
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Has Okun's Law Become Invalid in China?——Estimation of Potential GDP Growth Rates and Natural Rates of Unemployment Based on Dual Structure
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作者 邹沛江 《China Economist》 2014年第1期53-67,共15页
This paper calculates the potential GDP growth rates and the natural rates of unemployment in China using the dual decomposition of the simple Ohm's law.The results show that every 1%increase in China's urban ... This paper calculates the potential GDP growth rates and the natural rates of unemployment in China using the dual decomposition of the simple Ohm's law.The results show that every 1%increase in China's urban registered unemployment rate leads to a 1.98%drop of GDP,the potential growth rate of GDP of China is about 10%,and the average natural rate of unemployment is about 3.2%in China in the past three decades.The paper finds that Okun's law is still valid in China in the long run,but the Okun coefficient is about-3.79,overestimating the impact of the registered unemployment rate on GDP growth,and needs to be corrected based on China's dual economic structure. 展开更多
关键词 GDP增长率 失业率 中国 定律 自然 二元结构 国内生产总值 失效
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Study of Natural and Fishing Mortality and Exploitation Rate of Anchovy Kilka Clupeonella engraufiformis in Southeast Part of the Caspian Sea (Babolsar)
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作者 G. Karimzadeh 《Journal of Agricultural Science and Technology(B)》 2011年第2期272-277,共6页
关键词 自然死亡率 过度捕捞 里海 开采 东南部 系数估计 鳀鱼 凤尾鱼
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Capital Structure and Natural Rate of Unemployment: An Empirical analysis
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作者 Liu hui 《International English Education Research》 2014年第10期47-50,共4页
关键词 资本结构 失业率 自然 实证分析 马克思主义 循环模式 上升趋势 收入分配
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The migration of total dissolved solids during natural freezing process in Ulansuhai Lake 被引量:13
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作者 Yan ZHANG ChangYou LI +1 位作者 XiaoHong SHI Chao LI 《Journal of Arid Land》 SCIE 2012年第1期85-94,共10页
High total dissolved solids (TDS) content is one of the most important pollution contributors in lakes in arid and semiarid areas. Ulansuhai Lake, located in Urad Qianqi, Inner Mongolia, China, was selected as the o... High total dissolved solids (TDS) content is one of the most important pollution contributors in lakes in arid and semiarid areas. Ulansuhai Lake, located in Urad Qianqi, Inner Mongolia, China, was selected as the object of study. Temperatures and TDS contents of both ice and under-ice water were collected together with corresponding ice thickness. TDS profiles were drawn to show the distribution of TDS and to describe TDS migration. The results showed that about 80% (that is 3.602x108 kg) of TDS migrated from ice to water during the whole growth period of ice. Within ice layer, TDS migration only occurred during initial ice-on period, and then perished. The TDS in ice decreased with increasing ice thickness, following a negative exponential-like trend. Within un- der-ice water, the TDS migrated from ice-water interface to the entire water column under the effect of concentra- tion gradient until the water TDS content was uniform. In winter, 6.044x 107 kg (16.78% of total TDS) TDS migrated from water to sedirnent, which indicated that winter is the best time for dredging sediment. The migration effect gives rise to TDS concentration in under-ice water and sediment that is likely to affect ecosystem and water quality of the Yellow River. The trend of transfer flux of ice-water and water-sediment interfaces is similar to that of ice growth rate, which reveals that ice growth rate is one of the determinants of TDS migration. The process and mechanism of TDS migration can be referenced by research on other lakes with similar TDS content in cold and arid areas. 展开更多
关键词 arid and semiarid areas Ulansuhai Lake total dissolved solids (TDS) migration natural freezing process transferflux ice growth rate
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Gas-water-rock interactions and factors affecting gas storage capacity during natural gas storage in a low permeability aquifer 被引量:2
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作者 TOOSEH Esmaeel Kazemi JAFARI Arezou TEYMOURI Ali 《Petroleum Exploration and Development》 2018年第6期1123-1128,共6页
Gas-water-rock interactions during natural gas storage in a low permeability aquifer and main factors affecting the storage capacity were investigated in laboratory with core experiments. The results showed that gas i... Gas-water-rock interactions during natural gas storage in a low permeability aquifer and main factors affecting the storage capacity were investigated in laboratory with core experiments. The results showed that gas injection flow rate had a major impact on stored gas volume and stored gas volume is higher at high flow rate. Gas storage volume ranged between 6%-20% of the pore space at experimental condition. Enhancing injection pressure can enhance gas storage volume. Statistics showed that injection flow rate had a greater influence on the gas storage volume than pressure. The retention time also had an impact on the gas storage process. Most of the natural gas was trapped in the reservoir and could not be produced after long time of retention. Atomic absorption spectroscopy indicated that ions concentrations of the brine and water evaporation increased when gas was injected into brine saturated core, and precipitation might occur, reducing porosity and permeability of core. Gas chromatography analysis showed that the concentration of carbon dioxide in the natural gas decreased and the concentration of methane increased after storage in the core. 展开更多
关键词 UNDERGROUND GAS STORAGE natural GAS GAS STORAGE volume AQUIFER GAS INJECTION rate GAS INJECTION pressure
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An Analysis for Distribution of Natural Radionuclides in Soil, Sand and Sediment of Potenga Sea Beach Area of Chittagong, Bangladesh 被引量:1
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作者 Sabina Yasmin Bijoy Sonker Barua +1 位作者 Masud Kamal Md. Abdur Rashid 《Journal of Environmental Protection》 2014年第17期1553-1563,共11页
A HPGe (High Purity Germanium) detector based, low background gamma-ray counting system was used for activity measurement in soil, sand and sediment samples collected from Potenga sea beach area of Chittagong, Banglad... A HPGe (High Purity Germanium) detector based, low background gamma-ray counting system was used for activity measurement in soil, sand and sediment samples collected from Potenga sea beach area of Chittagong, Bangladesh. The specific radioactivities of Radium (226Ra), Thorium (232Th) and Potassium (40K) were measured in the above samples. The investigation reflects the lower deposition of minerals exist in the collected samples. From the measured specific radioactivities of the above three natural radionuclides, the radium equivalent activity (Raeq), the external hazard index (Hex), the external gamma absorbed dose rate and the annual effective dose were calculated. The obtained mean values of gamma absorbed dose rate in soil and sand samples and annual effective dose in soil, sand and sediment samples were found higher than the worldwide average as reported by United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR, 2000). The Raeq values were in the range of 47.86 to 293.76 Bq·kg-1 and the Hex varied from 0.13 - 0.81, which indicated that the study area was radiologically safe for human being. 展开更多
关键词 natural RADIOACTIVITY Specific RADIOACTIVITY HPGE Γ-RAY Detector Radiation Hazard Index Dose rate Potenga SEA BEACH
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The 2010–2020 National Natural Science Foundation of China:Radiation Therapy 被引量:1
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作者 Jun LIU Yang LI Rong SHI 《Current Medical Science》 SCIE CAS 2022年第2期453-461,共9页
Objective This study explains the application number and funding rate of oncology projects undertaken by the National Natural Science Foundation of China(NSFC),with focus on tumor radiotherapy-related research over th... Objective This study explains the application number and funding rate of oncology projects undertaken by the National Natural Science Foundation of China(NSFC),with focus on tumor radiotherapy-related research over the past 11 years.Methods A stratified analysis was carried out on the application and funding status of tumor radiotherapy studies in different NSFC project categories,different research areas,and different tumor types.Research areas that required specific focus,such as immunology-related radiotherapy,multimodality imaging and radiomics,and post-radiotherapy organ injury,were separately analyzed.Results The status and development trends of various related research fields were studied,and the research results were presented with the support of the NSFC,in order to provide reference for future applications and funding allocations.Conclusion The number of applications for funding increases every year.Although the total number of funded projects has also increased every year,the funding rate has decreased year by year.Projects on radiotherapy and immunization have been at the forefront in recent years,and the funding rate for these projects increases yearly. 展开更多
关键词 National natural Science Foundation of China radiation therapy funding rate
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Plan C: China’s Development under the Scarcity of Natural Capital 被引量:4
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作者 Zhu Dajian Wu Yi 《Chinese Journal of Population,Resources and Environment》 北大核心 2007年第3期3-8,共6页
The critical issue of China’s modernization is whether it can free itself from the traditional modernization plan based on the relatively abundant natural capital, and innovatively create a developmental model of a l... The critical issue of China’s modernization is whether it can free itself from the traditional modernization plan based on the relatively abundant natural capital, and innovatively create a developmental model of a large country under the scarcity of natural capital. This is why China is so keen on circular economy and economical use of resources. Focused on this issue, this paper summarizes the theoretical elements of the development under the scarcity of natural capital, points out that Plan C is the strategic choice for China’s future development, emphasizes that China needs to enhance the new industrialization, new urbanization and new modernization based on the restriction of natural capital, and discusses the technological and mechanistic support required to realize the development under the scarcity of natural capital. 展开更多
关键词 中国 自然资源 现代化 发展 循环经济 C计划 工业化 城市化
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Changes in Natural Mortality of Atlantic Cod(Gadus morhua) on Eastern Georges Bank 被引量:1
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作者 WANG Yanjun 《Journal of Ocean University of China》 SCIE CAS 2016年第5期879-889,共11页
The assessment of Eastern Georges Bank cod with the assumption of a constant natural mortality of 0.2 has over-estimated stock productivity, resulting in a severe retrospective pattern since the late 2000 s. Comparing... The assessment of Eastern Georges Bank cod with the assumption of a constant natural mortality of 0.2 has over-estimated stock productivity, resulting in a severe retrospective pattern since the late 2000 s. Comparing relative exploitation rate(ratio of fishery catch at age to survey abundance indices at age) with total mortality calculated from the age distribution in surveys indicated a conflict when constant natural mortality was assumed. This inconsistency implies an increase in natural mortality since the mid-1990 s. In this paper, natural mortality estimated by Virtual Population Analysis(VPA) indicated that natural mortality for this stock has increased to 0.8 since the mid-1990 s for ages 6+. Potential factors contributing to this elevated natural mortality, including poor fish conditions and increased losses due to seal predation were discussed. 展开更多
关键词 Eastern Georges Bank cod natural mortality relative exploitation rate Virtual Population Analysis age structure fish condition seals predation
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Assessment of Exposure Due to Technologically Enhanced Natural Radioactivity in Various Samples of Moroccan Building Materials 被引量:1
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作者 Bouchaib Kassi Aziz Boukhair +3 位作者 Khadija Azkour Mohamed Fahad Mohammed Benjelloun Abdel-Mjid Nourreddine 《World Journal of Nuclear Science and Technology》 2018年第4期176-189,共14页
The aim of our present work is to measure the specific activities of the radionuclides 226Ra, 232Th, 40K and the exhalation rates in terms of area and mass of 222Rn in some samples of building materials commonly used ... The aim of our present work is to measure the specific activities of the radionuclides 226Ra, 232Th, 40K and the exhalation rates in terms of area and mass of 222Rn in some samples of building materials commonly used in Morocco in order to evaluate the radiological risk caused by natural radioactivity. To this end, the analyses were carried out, using two nuclear techniques, namely high resolution gamma spectrometry and alpha dosimetry based on the use of LR115, on 50 samples collected from large commercial suppliers in Morocco. The results of these analyses show that the average specific activities of 226Ra, 232Th and 40K in these materials vary from 9 to 52 Bq/kg, 3 to 63 Bq/kg and 68 to 705 Bq/kg respectively. These activities remain within the permissible limits of 35 Bq/kg, 30 Bq/kg and 370 Bq/kg respectively, with the exception of a few samples of red brick, gray cement, ceramic and granite. The activity of the radium equivalent (Raeq), the internal (Hin) and external (Hex) hazard indices, the absorbed dose rate, the total annual effective dose , the excess lifetime cancer risk (ELCR) as well as volumic activities, exhalation rates in terms of area (ES) and mass (EM) are calculated for the samples analyzed in this work in order to assess the radiological risks resulting from the use of these materials in various construction activities. It seems that the values of these indices vary from 19 to 196 Bq/kg, 0.08 to 0.67, 0.05 to 0.53, 9 to 91 nGy/h, 0.05 to 0.56 mSv/y, 0.19 × 10&minus;3 to 1.96 × 10&minus;3, 72 to 350 Bq/m3, 56 to 273 mBq&sdot;m&minus;2&sdot;h&minus;1 and 3 to 15 mBq&sdot;kg&minus;1&sdot;h&minus;1 respectively. The lowest values are identified for gypsum, while the highest are attributed to granite. All of the obtained results of these indices respect the permissible limits except for the Raeq in some granite samples, the ELCR index in all samples except gypsum and the radon volumic activity in some gray cement samples, ceramic and granite. As a result, the different types of building materials analyzed in our work do not present a health risk to the public and can be used in various construction activities, with the exception of a few samples of red brick, gray cement, ceramic and granite. The choice of the use of red brick, gray cement and ceramic should be monitored and adapted according to the criteria of the limitation of the doses whereas the use of the granite must be moderate in order to limit over time the health risk which increases with the duration of exposure of humans to these building materials. 展开更多
关键词 Building Materials natural RADIOACTIVITY RADIONUCLIDE RADON EXHALATION rate RADIUM Equivalent Annual Effective Dose
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NATURAL BACKGROUND RADIOACTIVITY LEVELS IN THE TERRESTRIAL ENVIRONMENT OF HONG KONG
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作者 关祖杰 余君岳 +1 位作者 杨健明 M.J.Stokes 《Nuclear Science and Techniques》 SCIE CAS CSCD 1993年第3期151-157,共7页
This paper analyses and summarizes the natural radionuclide contents of soil and building materials, radon concentrations and the penetrating radiation levels in Hong Kong. From these, a thorough and objective assessm... This paper analyses and summarizes the natural radionuclide contents of soil and building materials, radon concentrations and the penetrating radiation levels in Hong Kong. From these, a thorough and objective assessment for the terrestrial background irradiation level of Hong Kong was made. Finally, the annual effective dose equivalent received by Hong Kong people due to the natural background irradiation was calculated to be 3.2 mSv. 展开更多
关键词 natural RADIOACTIVITY Absorbed GAMMA DOSE rate Indoor RADON Soil and building materials Background levels Effective DOSE EQUIVALENT
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