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活络散结汤治疗痰瘀互结证渗出性年龄相关性黄斑变性临床效果 被引量:4
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作者 汪兵 《当代医学》 2018年第22期52-54,共3页
目的活络散结汤治疗痰瘀互结证渗出性年龄相关性黄斑变性临床效果。方法选取门诊治疗的58例患者(62眼),收治时间为2014年3月7日~2016年3月8日,采用电脑软件随机抽签的方式把患者分为对照组与观察组,每组29例(31眼),对照组采用维生素E+... 目的活络散结汤治疗痰瘀互结证渗出性年龄相关性黄斑变性临床效果。方法选取门诊治疗的58例患者(62眼),收治时间为2014年3月7日~2016年3月8日,采用电脑软件随机抽签的方式把患者分为对照组与观察组,每组29例(31眼),对照组采用维生素E+维生素C+葡萄糖酸锌片治疗,观察组采用活络散结汤进行治疗,对比两组治疗结果。结果观察组临床疗效82.76%,对照组临床疗效58.62%,观察组明显高于对照组,差异有统计学意义(P<0.05);观察组OCT疗效为80.65%,对照组OCT疗效为51.61%,观察组明显高于对照组,差异有统计学意义(P<0.05)。结论活络散结汤治疗痰瘀互结证渗出性年龄相关性黄斑变性效果显著,值得推广。 展开更多
关键词 活络散 痰瘀互证渗出性年龄相关性黄斑变性 临床效果
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人口因素对区域教育“十三五”规划制定的影响 被引量:1
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作者 肖庆顺 《天津市教科院学报》 2015年第5期12-13,共2页
人口对区域教育发展具有重要的影响,也是影响区域教育发展规划制定的重要因素。当前,各地正在制定本区域的教育事业发展"十三五"规划,人口因素是教育规划制定的重要依据。随着经济社会的发展和城镇化发展,人口因素本身日益呈... 人口对区域教育发展具有重要的影响,也是影响区域教育发展规划制定的重要因素。当前,各地正在制定本区域的教育事业发展"十三五"规划,人口因素是教育规划制定的重要依据。随着经济社会的发展和城镇化发展,人口因素本身日益呈现出复杂性的趋势,人口的数量、结构、流动和人口政策的调整都会影响到区域教育发展,影响到教育发展规划中战略重点、重点项目或工程的设计。在区域教育规划制定中,要做好科学的人口预测。 展开更多
关键词 人口因素 区域教育 教育规划 影响区域 人口政策 战略重点 重点项目 教育事业 人口预测 人口年龄结
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Development and Age Structure of Ramets of Kalimeris integrifolia Populations in the Songnen Plains, Northeast China 被引量:6
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作者 杨允菲 王升忠 李建东 《Acta Botanica Sinica》 CSCD 2003年第2期158-163,共6页
Kalimeris integrifolia Turcz. is a root sucker form perennial herb of Compositae. In die late period of growing season, fresh fleshy radicels grow up above the soil surface to develop root-borne buds, which in turn gr... Kalimeris integrifolia Turcz. is a root sucker form perennial herb of Compositae. In die late period of growing season, fresh fleshy radicels grow up above the soil surface to develop root-borne buds, which in turn grow into ramets and taproot. On the basis of observation on numerous samples, methods to classify the age of ramets and buds for the root sucker herbaceous plant population and to estimate the ages of taproots were established according to their morphology. The age of ramets was classified based on the regeneration times of taproot buds. Ramets developed from new root sucker buds were classified as 1 a. After 1 a ramets died, the ramets reproduced from the taproots were 2 a, and so on. New buds from a root sucker were 0 a buds, other age classes of buds were consistent with that of ramets, i.e. buds produced from taproots of I a ramets were 1 a buds, and so on. In the hay clipping meadows of the Songnen Plains, for K. integrifolia population, there are three age classes of ramets, representing a steady age structure. The maximal age of taproots of ramets is 4 a. Among all age classes, the population productivity of 2 a ramets was the highest, and that of I a ramets was the lowest. The ramet productivity increased with ramet age. During the early period of growing season, the productivity of 3 a ramets was the highest, but after the middle of growing season, I a ramets showed the greatest relative growth rate. The population size and age structure in the next year could be accurately forecasted by the number of fresh roots with budlet and present population in late autumn. The potential population in the bud banks was more than two times of the present population, which may provide sufficient substitution in the future. 展开更多
关键词 Kalimeris integrifolia CLONE RAMET TAPROOT bank of bud age structure productivity
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Analysis on age structure of Zoysia japonica (Poaceae) population 被引量:1
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作者 王艳 代保清 +1 位作者 梁永军 马连菊 《Journal of Forestry Research》 SCIE CAS CSCD 2003年第1期64-66,共3页
The age-structure of natural population of Zoysia japonica in Xiuyan County of Liaoning Province was studied by generational method. The results showed that the highest tiller age class was three, but 1st age class ti... The age-structure of natural population of Zoysia japonica in Xiuyan County of Liaoning Province was studied by generational method. The results showed that the highest tiller age class was three, but 1st age class tillers held dominant posi-tion with proportions over 95% in each month during the growing seasons. The 2nd age class and 3rd age class tillers were minority in the population. So Z. japonica population was an expanding population. The zero age class buds on the rhizomes were dominant in buds age structures. The proportion of buds to tillers on quantity in each month was about 30% to 40% and reached the highest at the end of September. The increasing of buds proportion before dormancy guaranteed the quantity of tillers in the next spring. The biomass of 1st age class tillers changed with time. The biomass kept increasing from April to July and reached the highest at the end of July and then decreased. 展开更多
关键词 Zoysia japonica Age structure Clonal population
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合理调配人力资源 加强人才队伍建设
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作者 徐全兵 《学习月刊》 2015年第22期83-,共1页
随着交通公路行业建设发展的不断推进,一方面新技术、新材料、新工艺的推广应用迫切需要行业人才素质不断提高,另一方面社会公众需求增高、产业结构升级等客观因素又使行业人才需求趋于多样化。这些都给公路行业人力资源管理带来新的挑... 随着交通公路行业建设发展的不断推进,一方面新技术、新材料、新工艺的推广应用迫切需要行业人才素质不断提高,另一方面社会公众需求增高、产业结构升级等客观因素又使行业人才需求趋于多样化。这些都给公路行业人力资源管理带来新的挑战和机遇。笔者就所在基层公路部门的现状,浅析如何合理调配人力资源,加强人才队伍建设。一、公路基层单位人力资源的现状1、职工年龄结构不合理。 展开更多
关键词 人力资源 公路基层 人才使用 行业建设 交通公路 行业人才 产业 人才资源开发 人才选拔 年龄结
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中兴财光华会计师事务所有限责任公司
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《党史博采(下)》 2010年第7X期4-4,共1页
中兴财光华会计师事务所有限责任公司是由河北光华会计师事务所、中兴财会计师事务所、天津中兴财会计师事务所、北京恒介会计师事务所、江西人和会计师事务所合并成立。
关键词 会计师事务所 高级会计师 江西人 税务师 管理咨询师 国际注册 交通运输 资深教授 经济管理 年龄结
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Status of two Coreius species in the Three Gorges Reservoir,China 被引量:3
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作者 夏雨果 J.LLORET +6 位作者 李钟杰 张堂林 叶少文 李为 苑晶 H.A.C.C.PERERA 刘家寿 《Chinese Journal of Oceanology and Limnology》 SCIE CAS CSCD 2016年第1期19-33,共15页
Dam construction alters natural flow regimes which,in turn,cause significant changes in fish communities during and after impoundment. The construction of the Three Gorges Reservoir,from impoundment of the Changjiang(... Dam construction alters natural flow regimes which,in turn,cause significant changes in fish communities during and after impoundment. The construction of the Three Gorges Reservoir,from impoundment of the Changjiang(Yangtze) River,China,may have affected native fish species. Thus,the status of two lotic freshwater fish species,Coreius heterodon and C.guichenoti,were monitored in the Three Gorges Reservoir,including fish abundance,individual composition,growth,condition,and mortality. Data on both species were gathered from upstream,midstream and downstream areas of the reservoir and,where available,from studies published before and after dam construction. Lower abundance,slower growth,a less diversified age structure,poorer fish condition(indicated by hepatosomatic index) and higher mortalities were recorded in sites nearest the dam compared with upstream areas. Furthermore,after final impoundment,individual Coreius species inhabiting the area changed,with young individuals becoming more abundant,while upstream of the reservoir the two Coreius species became smaller at a given age. The results show that the status of the two Coreius species was subject to dramatic changes after impoundment. 展开更多
关键词 Three Gorges Reservoir Coreius species STATUS age profile GROWTH IMPOUNDMENT
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Estimating time-based instantaneous total mortality rate based on the age-structured abundance index 被引量:1
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作者 王迎宾 JIAO Yan 《Chinese Journal of Oceanology and Limnology》 SCIE CAS CSCD 2015年第3期559-576,共18页
The instantaneous total mortality rate(Z) of a fish population is one of the important parameters in fisheries stock assessment. The estimation of Z is crucial to fish population dynamics analysis,abundance and catch ... The instantaneous total mortality rate(Z) of a fish population is one of the important parameters in fisheries stock assessment. The estimation of Z is crucial to fish population dynamics analysis,abundance and catch forecast,and fisheries management. A catch curve-based method for estimating time-based Z and its change trend from catch per unit effort(CPUE) data of multiple cohorts is developed. Unlike the traditional catch-curve method,the method developed here does not need the assumption of constant Z throughout the time,but the Z values in n continuous years are assumed constant,and then the Z values in different n continuous years are estimated using the age-based CPUE data within these years. The results of the simulation analyses show that the trends of the estimated time-based Z are consistent with the trends of the true Z,and the estimated rates of change from this approach are close to the true change rates(the relative differences between the change rates of the estimated Z and the true Z are smaller than 10%). Variations of both Z and recruitment can affect the estimates of Z value and the trend of Z. The most appropriate value of n can be different given the effects of different factors. Therefore,the appropriate value of n for different fisheries should be determined through a simulation analysis as we demonstrated in this study. Further analyses suggested that selectivity and age estimation are also two factors that can affect the estimated Z values if there is error in either of them,but the estimated change rates of Z are still close to the true change rates. We also applied this approach to the Atlantic cod(G adus morhua) fishery of eastern Newfoundland and Labrador from 1983 to 1997,and obtained reasonable estimates of time-based Z. 展开更多
关键词 instantaneous total mortality rate (Z) catch per unit effort (CPUE) time-based change trend SIMULATION SELECTIVITY incorrect age estimation
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Predisposing factors for atrial fibrillation in the elderly 被引量:5
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作者 Kristina Wasmer Lars Eckardt Gunter Breithardt 《Journal of Geriatric Cardiology》 SCIE CAS CSCD 2017年第3期179-184,共6页
Atrial fibrillation (AF) in the elderly occurs as a consequence of cardiovascular aging and an age related increase of comorbidity. Several predisposing factors for AF have been identified for the overall AF populat... Atrial fibrillation (AF) in the elderly occurs as a consequence of cardiovascular aging and an age related increase of comorbidity. Several predisposing factors for AF have been identified for the overall AF population. Most of them, cardiovascular disease in particular, play a role in younger and older patients. The longer time period during which these risk factors can cause structural changes that ultimately lead to AF may, at least in part, explain the association between age and AF. In addition, less well defined age-related changes in cellular electrophysi- ologic properties and structure predispose to AF in the elderly. 展开更多
关键词 Atrial fibrillation Atrial fibrosis MECHANISMS Risk factors STROKE The elderly
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Failed biliary cannulation: Clinical and technical outcomes after tertiary referral endoscopic retrograde cholangiopancreatography 被引量:6
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作者 Michael P Swan Michael J Bourke +4 位作者 Stephen J Williams Sina Alexander Alan Moss Rick Hope David Ruppin 《World Journal of Gastroenterology》 SCIE CAS CSCD 2011年第45期4993-4998,共6页
AIM: Prospective evaluation of repeat endoscopic retrograde cholangiopancreatography (ERCP) for failed Schutz grade 1 biliary cannulation in a high-volume center. METHODS: Prospective intention-to-treat analysis of pa... AIM: Prospective evaluation of repeat endoscopic retrograde cholangiopancreatography (ERCP) for failed Schutz grade 1 biliary cannulation in a high-volume center. METHODS: Prospective intention-to-treat analysis of patients referred for biliary cannulation following recent unsuccessful ERCP. RESULTS: Fifty-one patients (35 female; mean age: 62.5 years; age range: 40-87 years) with previous failed biliary cannulation were referred for repeat ERCP. The indication for ERCP was primarily choledocholithiasis (45%) or pancreatic malignancy (18%). Successful biliary can- nulation was 100%. The precut needle knife sphincterotomy (NKS) rate was 27.4%. Complications occurred in 3.9% (post-ERCP pancreatitis). An identif iable reason for initial unsuccessful biliary cannulation was present in 55% of cases. Compared to a cohort of 940 nave pa-pilla patients (female 61%; mean age: 59.9 years; age range: 18-94 years) who required sphincterotomy over the same time period, there was no statistical difference in the cannulation success rate (100% vs 98%) or postERCP pancreatitis (3.1% vs 3.9%). Precut NKS use was more frequent (27.4% vs 12.7%) (P = 0.017). CONCLUSION: Referral to a high-volume center following unsuccessful ERCP is associated with high technical success, with a favorable complication rate, compared to routine ERCP procedures. 展开更多
关键词 Failed endoscopic retrograde cholangiopancreatography Failed biliary cannulation Unsuccessful biliary cannulation Tertiary referral endoscopic retrograde cholangiopancreatography Needle knife sphincterotomy Biliary cannulation Precut sphincterotomy Post endoscopic retrograde cholangiopancreatography pancreatitis
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Why Does China's Labor Income Share Tend to Decline?- From the Perspective of Population Age Structure Change 被引量:2
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作者 魏下海 董志强 赵秋运 《China Economist》 2013年第3期52-63,共12页
Using a theoretical model, this article concludes that age structures influence people's propensity to save and thereby influence their capital intensity. In the context that capital and labor are in a substitutional... Using a theoretical model, this article concludes that age structures influence people's propensity to save and thereby influence their capital intensity. In the context that capital and labor are in a substitutional relation, increased capital intensity may lead to a drop of labor income share. We perform empirical research with provincial-level data from 1990 to 2007 and have proved that the rising of the old dependency ratio and the decrease of the children dependency rate both contribute to the fall of labor income share. This assumption still holds true after the authors control the influences of other potential factors that may influence labor income share 展开更多
关键词 population age structure labor income share AGING
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Constraints on sedimentary ages of the Chuanlinggou Formation in the Ming Tombs, Beijing, North China Craton: LA-ICP-MS and SHRIMP U–Pb dating of detrital zircons 被引量:5
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作者 Jing Ding Yuruo Shi +1 位作者 Alfred Kroner J. Lawford Anderson 《Acta Geochimica》 EI CAS CSCD 2018年第2期257-280,共24页
Detrital zircons in five sedimentary samples, MC1 to MC5, from the bottom of the Chuanlinggou Formation in the Ming Tombs District, Beijing, were dated with the LA-ICP-MS and SHRIMP U-Pb methods. Age spectra of the fi... Detrital zircons in five sedimentary samples, MC1 to MC5, from the bottom of the Chuanlinggou Formation in the Ming Tombs District, Beijing, were dated with the LA-ICP-MS and SHRIMP U-Pb methods. Age spectra of the five samples show a major peak at 2500 Ma and a secondary peak at 2000 Ma, suggesting their provenances were mainly from the crystalline basement of the North China Craton and the Trans-North China Orogen. The youngest zircon has an age of 1673 d: 44 Ma, indicating that the Chuanlinggou Formation was deposited after this age. From sample MC4 to MC5, lithology changed from a clastic rock (fine-grained sandstone) to a carbonate rock (fine-grained dolomite), suggesting that the depositional basin became progressively deeper. The age spectrum of sample MC5 shows a major peak at 2500 Ma and a secondary peak at 2000 Ma. Sample MC4, which is stratigraphically lower than sample MC5, only had one peak at 2500 Ma. We conclude that there was a transgressive event when sediments represented by MC5 was deposited, and seawater carried ca. 2000 Ma clastic materials to the basin where the Chuanlinggou Formation was deposited, leading to the addition of ca. 2000 Ma detritus. Our research indicates that the source area for the sediments became more extensive with time. We conclude that the Chuanlinggou Formation in the Ming Tombs District was deposited in a low-energy mud fiat sedimentary environment in the inter-supra tidal zone because it is mainly composed of silty mudstone and fine-grained sandstone with relatively simple sedimentary structures. 展开更多
关键词 Detrital zircon LA-ICP-MS U-Pb ages SHRIMP Chuanlinggou Formation Ancient sedimentary environment North China Craton
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Retrospective Studies on Clinical Features of Melanosis of the Colon and Its Correlation with the Polypus and Carcinoma of Large Intestine 被引量:2
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作者 Qiong Nan Lei Zhang +3 位作者 Jian Shen Xiaoyan Li Yumei Yang Haiyan Jiang 《Chinese Journal of Clinical Oncology》 CSCD 2009年第2期138-141,共4页
OBJECTIVE To investigate the clinical characteristics of melanosis of the colon (MC) and its correlation with polypus and carcinoma of the large intestine. METHODS Clinical feature and colonoscopic findings of 156 M... OBJECTIVE To investigate the clinical characteristics of melanosis of the colon (MC) and its correlation with polypus and carcinoma of the large intestine. METHODS Clinical feature and colonoscopic findings of 156 MC patients were retrospectively analyzed. Final diagnosis of MC case was made after colonoscopic and pathological examination, and data of the case history was recorded. RESULTS The overall detection rate of MC was 1.12%, with 0.46% in males, 0.66% in females. An 82.69% of the patients suffered various constipations and had a history of taking cathartics. The clinical manifestation of total-colon melanosis occurred in 83.97% of the patients. There was no significant difference between the rate of concomitant polypus (27.56%) in the MC patients and the detection rate of polypus in the patients who underwent a synchronous colonoscopy (χ^2 = 1.205, P = 0.298). Also there was no significant difference between the detection rate of carcinoma of the large intestine (8.97%) in MC patients and the detection rate of the same disease in the patients who underwent synchronous colonoscopy (χ^2 = 0.268, P = 0.604). A logistic regression analysis has shown that the older the age of MC patients is, the more opportunities of MC and the concomitant polypus would occur. CONCLUSION MC may be related to constipations and a long-term administration of cathartics, among which total-colon melanosis ranks first in the cases. There is an earlier age of onset in the females, with a higher detection rate. The older the age of the patients is, the higher the detection rate of MC is, and the more possibility the onset of the concomitant polypus. 展开更多
关键词 melanosis of the colon large intestine intestinal polypus carcinoma of bowels retrospective study.
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Evaluation of deriving fire cycle of forested landscape based on time-since-fire distribution
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作者 ZHANG Quan-fa Kurt S. Pregitzer +1 位作者 JIANG Ming-xi CHEN wen-jun 《Journal of Forestry Research》 SCIE CAS CSCD 2006年第4期263-268,共6页
Estimation of fire cycle has been conducted by using the negative exponential function as an approximation of time-since-fire distribution of a landscape assumed to be homogeneous with respect to fire spread processes... Estimation of fire cycle has been conducted by using the negative exponential function as an approximation of time-since-fire distribution of a landscape assumed to be homogeneous with respect to fire spread processes. The authors imposed predefined fire cycles on a virtual landscape of 100 cell×100 cell, and obtained a mosaic composing of patches with different stand ages (i.e. time since fire). Graphical and statistical methods (Van Wagner 1978; Reed et al. 1998) were employed to derive fire cycle from the virtual landscape. By comparing the predefined and the derived fire cycles, the two methods and tested the effects of sample size and hazard of burning (i.e., stand's susceptibility to fire in relation to its stand age) were evaluated on fire cycle deviation. The simulation results indicated a minimum sample size of l0 times of the annual burnt area would be required for.partitioning time-since-fire distribution into homogeneous epochs indicating temporal change in fire cycle. Statistically, there was significant difference among the imposed and the derived fire cycle, regardless of sample sizes with or without consideration of hazard of burning. Both methods underestimated the more recent fire cycle without significant difference between them. The results imply that deviation of fire cycle based on time-since-fire distribution warrants cautious interpretation, especially when a landscape is spatially partitioned into small units and temporal changes in fire cycle are involved. 展开更多
关键词 Fire cycle Simulation Time-since-fire distribution EVALUATION
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Stable Solution of Nonlinear Age-structured Forest Evolution System
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作者 WANGDing-jiang ZHAOTing-fang 《Chinese Quarterly Journal of Mathematics》 CSCD 2004年第3期309-313,共5页
This paper studies the dynamical behavior of a class of total area dependent nonlinear age-structured forest evolution model. We give the problem of equal value for the forest system, and discuss the stable solution o... This paper studies the dynamical behavior of a class of total area dependent nonlinear age-structured forest evolution model. We give the problem of equal value for the forest system, and discuss the stable solution of system. We obtained the necessary and sufficient conditions for there exists the stable solution. 展开更多
关键词 NONLINEAR age-structured forest model stable solution
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Age distribution,polyps and rectal cancer in the Egyptian population-based cancer registry 被引量:14
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作者 Darlene Veruttipong Amr S Soliman +5 位作者 Samuel F Gilbert Taylor S Blachley Ahmed Hablas Mohamed Ramadan Laura S Rozek Ibrahim A Seifeldin 《World Journal of Gastroenterology》 SCIE CAS CSCD 2012年第30期3997-4003,共7页
AIM:To describe the clinical and epidemiologic profiles of the disease and to compare the findings with those generated from the previous hospital-based studies.METHODS:The Gharbiah cancer registry is the only populat... AIM:To describe the clinical and epidemiologic profiles of the disease and to compare the findings with those generated from the previous hospital-based studies.METHODS:The Gharbiah cancer registry is the only population-based cancer registry in Egypt since 1998.We analyzed the data of all colorectal cancer patients included in the registry for the period of 1999-2007.All medical records of the 1364 patients diagnosed in Gharbiah during the study period were retrieved and the following information abstracted:age,residence,diagnosis date,grade,stage,topology,clinical characteristics,and histology variables.Egyptian census data for 1996 and 2006 were used to provide the general population's statistics on age,sex,residence and other related demographic factors.In addition to age-and sex-specific incidence rate analyses,we analyze the data to explore the incidence distribution by rural-urban differences among the 8 districts of the province.We also compared the incidence rates of Gharbiah to the rates of the Surveillance Epidemiology and End Results(SEER) data of the United States.RESULTS:Over the 9 year-period,1364 colorectal cancer cases were included.The disease incidence under age 40 years was relatively high(1.3/10 5) while the incidence in the age groups 40 and over was very low(12.0/10 5,19.4/10 5 and 21.2/10 5 in the age groups 40-59 years,60-69 years and > 70 years,respectively).The vast majority of tumors(97.2%) had no polyps and 37.2% of the patients presented with primary lesions in the rectum.Colorectal cancer was more common in patients from urban(55%) than rural(45%) areas.Regional differences in colon and rectal cancer incidence in the 8 districts of the study province may reflect different etiologic patterns in this population.The registry data of Egypt shows a slightly higher incidence of colorectal cancer than the United States in subjects under age 40 years.The results also shows significantly lower incidence of colorectal cancer in subjects over age 40 years compared to the same age group in the United States SEER.CONCLUSION:Low rate of polyps,low incidence in older subjects,and high rate of rectal cancer in Egypt.Future studies should explore clinical and molecular disease patterns. 展开更多
关键词 Colorectal cancer Young-onset Polyps Developing countries Egypt
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Effects of Trawl Selectivity and Genetic Parameters on Fish Body Length Under Long-Term Trawling
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作者 YU Yang SUN Peng +4 位作者 CUI He SHENG Huaxiang ZHAO Fenfang TANG Yanli CHEN Zelin 《Journal of Ocean University of China》 SCIE CAS 2015年第5期835-840,共6页
Long-term fishing pressure affects the biological characteristics of exploited fish stocks. The biological characteristics of hairtail(Trichiurus lepturus) in the East China Sea are unable to recover because of long-t... Long-term fishing pressure affects the biological characteristics of exploited fish stocks. The biological characteristics of hairtail(Trichiurus lepturus) in the East China Sea are unable to recover because of long-term trawling. Fishing induces evolutionary effects on the fish's biological characteristics. Evidence of these changes includes small size at age, a shift to earlier age structure, and early maturation. Natural and artificial selection usually affect the fish's life history. Selection can induce different chances of reproduction, and individual fish can give a different genetic contribution to the next generation. In this study, analysis of time-dependent probability of significance and test of sensitivity were used to explore the effects of fish exploitation rate, mesh size, and heritability with long-term trawling. Results showed that fishing parameters were important drivers to exploited fish population. However, genetic traits altered by fishing were slow, and the changes in biological characteristics were weaker than those caused by fishing selection. Exploitation rate and mesh size exhibited similar evolutionary trend tendency under long-term fishing. The time-dependent probability of significance trend showed a gradual growth and tended to be stable. Therefore, the direction of fishing-induced evolution and successful management of fish species require considerable attention to contribute to sustainable fisheries in China. 展开更多
关键词 trawling pressure fish biological characteristics fishery management
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The Continuous Solutions of an Age-structured Host-Vector Epidemic Model
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作者 周义仓 蒋里强 《Chinese Quarterly Journal of Mathematics》 CSCD 1997年第4期91-97, ,共7页
In this paper the continuous solutions for an age-structured host-vector epidemic model are introduced and studied. The continuous solutions of the age-structured epidemic model are easy to investigate and use. The su... In this paper the continuous solutions for an age-structured host-vector epidemic model are introduced and studied. The continuous solutions of the age-structured epidemic model are easy to investigate and use. The sufficient conditions for existence and uniqueness of the continuous so lutions are established. 展开更多
关键词 EPIDEMIC age structure WELL-POSEDNESS
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Reexamining China's Demographic Transition and Age Structure
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作者 马瀛通 《China Economist》 2012年第4期20-28,共9页
This paper discusses the shortcomings of Western theories on demographic transition by comparing transitions in demographic structure for Europe and China. This paper further proposes several criteria for judging the ... This paper discusses the shortcomings of Western theories on demographic transition by comparing transitions in demographic structure for Europe and China. This paper further proposes several criteria for judging the direction of demographic transition and whether or not it has finished. Apart from establishing new theories of demographic transition and the trasition of demographic structure, this paper differentiates the concepts of "relative surplus population" and "relative suitable population," and "relative insufficient population" and identifies key demographic differences along the way. In doing so, this paper argues that China's demographic strueture is undergoing a process of rebalancing. 展开更多
关键词 relative surplus population demographic transition trasition ofdemographic structure unstable population quasi-stationary population
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Relating Demography to Trade Imbalances through Theoretical Modeling and Numerical Simulation
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作者 杨继军 马野青 《China Economist》 2011年第6期92-101,共10页
Demographic transitions occur at different times and speed across different economies, and age structures consequently differ across regions. Using a solvable four-phase model, we show that economies with a higher pro... Demographic transitions occur at different times and speed across different economies, and age structures consequently differ across regions. Using a solvable four-phase model, we show that economies with a higher proportion of working-age force and a lower dependency ratio tend to have higher savings rates. Because the demographic " center of gravity"for investment demand falls at a younger point in the age distribution than that of savings supply, countries with a younger age-distribution like those described above generate national savings in excess of domestic investment, resulting in a current account surplus. Numerical simulation supports this hypothesis. But the relative youth or age of a country's population reflects temporary demographic trends which change continuously. Therefore, while trade imbalances caused by demographic factors are structural and long-term, they are not permanent, and may be reversed by changes in age structure. 展开更多
关键词 age structure dependency ratio demographic transition current account balance
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