5 resultados para 370500 Demography
em Chinese Academy of Sciences Institutional Repositories Grid Portal
Resumo:
辽东栎是我国暖温带落叶阔叶林主要优势种之一。它具有很强的萌蘖能力,在东灵山地区存在于多种林分中,并成为辽东栎林和落叶阔叶混交林的优势种。本文以植物种群构件理论为基础,对辽东栎的种子、幼苗、幼树和成体四个阶段不同侧面进行了调查统计和试验分析。初步得出如下结果: 1. 种子库统计表明:(1)种子雨持续时间短、强度大,种子散落总密度为123个m~2。(2)土壤种子库存在时间约100天左右,种子密度最高时为42.7个/m~2。(3)土壤种子库输出途径主要有死亡后腐烂、发芽、动物当场取食和搬运,其中动物搬运是影响种子库动态的最重要因子。(4)动物搬运和取食是影响种子命运的主要因素,如果没有该因素的影响,辽东栎能够完成从种子到幼苗的过程;(5)被啮齿动物贮藏的种子大多被取食,极少存活;(6)地表覆盖物能减少动物搬运、取食的影响,但对成苗效果不明显。 2. 干旱处理和模拟去叶试验的结果表明:(1)干旱将显著降低单叶面积、叶面积比和叶比重,从而也显著降低了单株生物量,但根比重却较对照组有显著上升;(2)去叶显著提高了单株叶数、叶面积比和叶比重,尽管单株生物量只稍高于对照组。这说明了辽东栎幼苗在去叶后具有一定的补偿能力。 3. 芽的命运调查发现:(1)辽东栎的芽或保持休眠状态,或死亡后脱落,或分化为营养枝、雄花枝、雄花序、雌花枝和两花枝等;(2)不同生境中芽的命运不同,生活在林窗中的幼树上的芽分化为具有生殖功能的枝条的比例高于郁闭林中的幼树,而与成熟个体接近;(3)同一个体内部,上层芽分化为生殖枝的比例明显大于中、下层;(4)芽的命运与枝长关系密切,长枝上的芽分化为生殖枝的可能性较大;(5)结实枝的平均枝长、枝上平均叶数都明显高于非结实枝。 4. 构型分析表明:(1)不同发育阶段的辽东栎个体的分枝格局不同:幼苗阶段,高生长显著,枝条伸长较快,但分枝率低;幼树阶段,分枝率显著小于成株阶段;但上层枝条的平均枝节倾角大于其它两阶段,上层枝条的长度也大于成株阶段;成株阶段,冠幅迅速扩展,分枝率较前两时期显著增加,同时顶端优势减弱,引起休眠芽萌生苗的发生。(2)不同生境的辽东栎个体分枝格局也有较大差异:混交林中的辽栎个体多生活在林隙中,同灌丛中的个体相比,枝冠窄小,枝倾角较大,第一枝级枝条(上层)较长,但分枝率较小叶面积指数较低;枝、叶的方位角,叶倾角(上层)在不同生境中未发生显著变化。 5. 叶群体统计表明:(1)不同个体,同一个体内部不同层次,叶数量动态趋势都基本一致。现叶期和叶落半衰期很短,现叶方式为爆发型;(2)不同个体间叶期差异很大,暗示在辽东栎种群内部或许存在有强烈的遗传分化。 6. 对叶的生长和光合作用测定发现:(1)辽东栎叶的长度、面积和干重的增加有共同趋势:即在叶生长早期增加很快,其后渐渐降低,叶长度、面积约在六月初达极大值,叶干重稍后达极大值;(2)净光合速率在整个生生季里随叶的生长发育是先上升,至七月中旬达极大值,然后逐渐下降;而暗呼吸速率除在落叶前有微弱上升外,一直都处在下降状态;(3)叶的净光合速率日进程具“午休”现象,可能由高温和强光照引起;(4)叶的形成初期,碳的输入较高,展叶后约十天左右,输入输出达到平衡;碳输出在七月中旬达极大值,随后下降。可见:(5)叶的光合能力与叶的生长发育状况有密切关系。 7. 对叶养分季节动态的测定表明:(1)N、P、K、Ca、Mg、Fe等6种元素的浓度和贮量在叶的生活史中都发生了明显的季节变化,其中N、P、K等3种元素的浓度在展叶初期下降很快,随后逐渐下降的,但贮量是在7月下旬达到最大值;(2)Ca浓度和贮量整个生长季中一直保持上升趋势,Mg的季节变化无一定规律;(3)N、P、K、Mg都有一定程度的回收,其中N、P的回收率分别为67%和,Ca、Fe在叶中有所积累。 对栎属植物养分动态的比较分析表明:(1)落叶植物成熟叶中的N浓度显著高于常绿植物,但N、P的回收率与成熟叶中的浓度无明显相关性;(2)栎属植物的成熟叶和落叶中的N、P浓度间呈显著相关。
Resumo:
P-J Fit and P-O Fit are focus problems in the investigation field of industry and organization psychology. They have distinct influences on staff job performance and job attitude. In a certain extend,these influences are moderated by some variables. LMX(Leader-member Exchange) and TMX(Team-member exchange) are two most important personal relationship types in job scene. Post investigations indicated that they are equal to forecasting variables and moderating variables of staff job performance and job attitude. From actualities, although there are many investigations about the relationships between P-J Fit, P-O Fit, LMX, TMX and job attitude, these investigations only focused on some aspects, and they discussed little about four aspects at one time and mutual influences. Using hierarchical regression analysis to analyze the survey data collected from 592 employees in a big governmental telecom company, we got some results as follows: (1)After controlling demography variables, standardized regression coefficients on P-J Fit, P-O Fit, LMX, TMX and job satisfaction, organization commitment are all positive, and reach distinct levels. (2) LMX could distinctly moderate the influences of P-J Fit, P-O Fit on job satisfaction, but couldn’t distinctly moderate the influences of the two on organization commitment. Specifically, as LMX increased,the effect of P-J on job satisfaction decreased gradually,while the effect of P-O increased. (3) TMX could not distinctly moderate the relationships between P-J Fit, P-O Fit, job satisfaction and organization commitment. The theoretical implication of this investigation lies in enriching and developing investigations in these fields in a certain extend, through conforming the influences of P-J Fit, P-O Fit, LMX, and TMX on job satisfaction and organization commitment. The practical implication lies in revealing these aspects for corporation governors: When selecting applications for a job, they should try their best to realize the best fit of personal ability and the job requirements, personal value and organization culture. They should enhance staff job satisfaction and organization commitment through furthering the relationship between the leader and members, team members each other. They should cushion disadvantage influences of non-P-J Fit on staff job satisfaction and enhance positive influences of P-O Fit. 【Key words】 person-job fit; person-organization fit; leader-member exchange; team member exchange; job attitude
Resumo:
Obsessive-Compulsive Symptoms, which are one of common factors effected on mental health of secondary school students, have been rarely studied at home and abroad. In accordance with the problems existed in these literature up till now, the thesis had mainly studied the measured tool, contents and structure, developmental features, psychosocial risk factors and integrated model of obsessive-compulsive symptoms from them by means of investigation with quetionnaires. The entire research was divided into three phases. 3185 students(age 14.68±1.75 years) were firstly measured with the 20-item Leyton Obsessional Inventory-Child Version(LOI-CV) at four secondary schools including six grades in Beijing city, which was applied to revise LOI-CV, and to study the structure and contents, developmental features and screen of obsessive-compulsive symptoms. Then, 216 subjects with obsessive-compulsive symptoms, paired with controls in the light of school, grade and gender, were investigated with 10 self-rating scales on obsessive-compulsive symptoms, anxiety, depression, personality, coping and attributional style, negative life events, parent's rearing style, family environment and life adaptation in school, and with an inventory on social demography. The results were used to explore psychosocial risk factors and integrated model of obsessive-compulsive symptoms. The third survey was only carried out, about two months after the second, among 264 subjects with obsessive-compulsive symptoms through MMOCI and Negative Life Event Scale for Adolescents, in order to probe into the integrated model. The research had mainly found: (1) LOI-CV can be used as a screen tool for obsessive-compulsive symptoms in urban adolescents in China; (2) Total screening-out ratio of obsessive-compulsive symptoms was 13.6% (male:15.0%, female:12.2%). The most common manifestations of obsessive-compulsive symptoms were hating dirt and contamination, doing things in exact manner, angry if someone messes desk, bad conscience but no one else, worry about cleanliness, repeated thoughts or words; the least were favorite or special number, spending extra time on homework, special number or words to avoid, talking or moving to avoid bad luck, fussy about hands. The checking and repetition, cleanliness and tidiness, general obsessions were more common forms than numbers-luck; (3) No differences were existed in serious degree of obsessive-compulsive symptoms, but the screening-out ratio in male was higher than it in female; (4) No differences were detected in the serious degree of obsessive-compulsive symptoms except the scores of cleanliness and tidiness among grades, but the screening-out ratio of the grades justly entering secondary school or going to graduate were higher than other ones; (5) The main psychosocial risk factors for obsessive-compulsive symptoms included anxiety, mother's over-protecting and over-interfering, fantasy, flexibility, self-actualization, peers relationship, sense of responsibility, negative life events, mother's occupation, help-seeking, and (6) The integrated model on psychosocial risk factors suggested that the possible developed and sustained mechanism of obsessive-compulsive symptoms was that personality, coping and attributional styles constructed the developmental diathesis foundation of obsessive-compulsive symptoms; negative life events were promoting factors of them. There was a dynamic interaction between personality and environmental factors. Negative emotion played a core role in the developmental process of them. The continued existence of obsessive-compulsive symptoms was related to pre-existed obsessive-compulsive symptoms and negative life events experienced by an individual. Therefore, this research not only let us get a deeper understanding of obsessive-compulsive symptoms and more entirely find out psychosocial risk factors, firstly applied diathesis-stress theory to comprehend the psychological mechanism of obsessive-compulsive symptoms and, moreover, elaborate and expand it, but also has more important practice significance of treatment, prevent and education for obsessive-compulsive symptoms in secondary school students.