99 resultados para AK44-5000


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高原急性影响中 ,出现体重暂时性下降 ,食欲减退等现象。随习服的产生 ,代谢变化明显减弱或消失。人类在5000m以上时代谢变化变得更为明显并不断发展则体脂和蛋白储备明显减少 ,血液中红细胞大量增加、血液粘稠度增大等。与此同时也产生一系列神经内分泌改变。下丘脑 腺垂体 甲状腺轴是调节体内代谢的重要因素之一 ,因而HPT轴低氧应答的研究对低氧习服和内环境的适应性反应有着重要价值。

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黑颈鹤的种群总量有5000~6000 只个体,主要分布在青藏高原和云贵高原,分布区约22 ×105km2 ,占有面积约5400 km2 。青藏高原北部和西部为其繁殖区,越冬区主要在雅鲁藏布江河谷中段、喜马拉雅山脉南坡及云贵高原部分区域,青藏高原东部为其迁徙途径之地。越冬时以家族、同种群及混合群(主要与灰鹤Grus grus 和斑头雁A nser indicus) 形式集群活动。繁殖期分化为非繁殖群和繁殖对(Breeding pair) 两种类型。繁殖对能否成功地占有领域是繁殖成败的关键。笔者认为该物种依IUCN(1994) 标准应列为易危级(Vulnerable ,VU)

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Adaptation to hypoxia is regulated by hypoxia-inducible factor 1 (HIF-1), a heterodimeric transcription factor consisting of an oxygen-regulated a-subunit and a constitutively expressed beta-subunit. How animals living on Qinghai-Tibetan plateau adapt to the extreme hypoxia environment is known indistinctly. In this study, the Qinghai yak which has been living at 3000-5000 m attitude for at least two millions of years was selected as the model of high hypoxia-tolerant adaptation species. The HIF-1 alpha ORFs (open reading frames) encoding for two isoforms of HIF-1 alpha have been cloned from the brain of the domestic yak. Its expression of HIF-1 alpha was analyzed at both mRNA and protein levels in various tissues. Both its HIF-1 alpha mRNA and protein are tissue specific expression. Its HIF-1 alpha protein's high expression in the brain, lung, and kidney showed us that HIF-1 alpha protein may play an important role in the adaptation to hypoxia environment. (c) 2006 Elsevier Inc. All rights reserved.

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Leptin, an adipocyte-derived hormone, plays all important role in body energy homeostasis. Plateau pika (Ochotona curzoniae), an endemic and keystone species living only at 3000-5000 in above sea level oil Qinghai-Tibet Plateau, is a typically high hypoxia and low temperature tolerant mammal with high resting metabolic rate (RMR), non-shivering thermogenesis (NST), and high ratio of oxygen utilization to cope with harsh plateau environment. To explore the molecular mechanism of ecological acclimation in plateau pika, we first cloned pika leptin cDNA and compared its mRNA expression in different altitudes (3200 and 3900 in) using real-time RTPCR (Taqman probe) technology. The full-length pika leptin cDNA was 3015 with 504 bp open-reading frame encoding the precursor peptide of 167 amino acids including 21 residues of signal peptide. Pika leptin was 70-72% homologous to that of other species and was of similarly structural characteristics with other species. The pika-specific genetic diversity in leptin sequence occurred at twenty sites. With the increase in attitude, there were larger fat store and high level of ob gene expression in plateau pika. Our results indicated that leptin is sensitive to cold and hypoxia plateau environment and may play one of important roles in pika's ecological adaptation to harsh plateau environment. (c) 2006 Elsevier Inc. All rights reserved.

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The effects of hypoxia on the levels of essential macroelements and trace elements (K, Na, Ca, Mg, Cu, Zn, Fe, and Mn) in the heart muscles of Wistar rats and plateau pikas (Ochotona curzoniae) were studied by atomic absorption spectrometry. Unlike the rat, the plateau pika is tolerant to hypoxia. The levels of K, Na, and the trace element Mn were not significantly changed in rat or pika hearts after exposure to hypoxia for 1, 10, or 25 d at simulated altitudes of 5000 and 7000 m. Other minerals (Ca, Mg, Cu, Zn, and Fe) were significantly affected by hypoxia and the levels followed different time-courses under different hypoxic regimes in these two animals. There were marked differences between the rat and pika in myocardial accumulation of essential elements such as Ca, which was increased to high levels in the rat but not affected in the pika. The results suggest that hypoxia affects animal physiological mechanisms by regulating the levels of essential elements.

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The formation of civilization, one of great marks in the history of human's society development, has been remained one of the hottest topics in the world. Many theories have been put ford to explain its causes and mechanisms. Although more attentions have been paid to its development, the role of environmental change should not be ignored. In this paper, the level of ancient farming productivity was analyzed, the mechanisms and the process of Chinese ancient civilization formation was explored, and some causes why Chinese ancient civilization shows many different features from other 5 ancient civilizations of the world was analyzed. The main results and conclusions are presented as followed. 1. Compared with the productivity level of other five ancient civilizations, the productivity of ancient China characterized by a feature of extensive not intensive cultivation was lower than that of other five ancient civilizations whose agriculture were based on irrigation. 2. The 5 5000 a B.P. cold event may have facilitated the formation of Egypt and Mesopotamian ancient civilizations and also have had an influence on the development of Neolithic culture in China. 3. The 4 000 a B.P. cold event, which may be the coldest period since the Younger Dryas cold event and signifies the changes from the early Holocene Climate Optimum to late Holocene in many regions of the world, resulted in the great migration of the Indo-European peoples from north Europe to other part of the World and the collapses of ancient civilizations in Egypt, Indus and the Mesopotamian and the collapse of five Neolithic cultures around central China. More important than that is the emergence of Chinese civilization during the same period. Many theories have been put ford to explain why it was in Zhongyuan area not other places whose Neolithic cultures seem more advanced that gave rise to civilization. For now no theory could explain it satisfiedly. Archaeological evidence clearly demonstrate that war was prevailed the whole China especially during the late Longshan culture period, so it seemed war has played a very important role in the emergence of China ancient civilization. Carneiro sees two conditions as essential to the formation of complex societies in concert with warfare, i.e. population growth and environmental circumscription. It was generally through that China couldn't evolved into the environmental circumscription and population pressure because China has extensive areas to live, but that depends on situations. The environmental circumscription area was formed due to the 4000a B.P. cold event and companied flooding disasters, while the population pressure is formed due to three factors; 1) population grow rapidly because of the suitable environment provided by the Holocene Optimum and thus laid its foundations for the ancient human population; 2) population pressure is also related to the primitive agricultural level characterized by extensive not intensive cultivation; 3) population pressure was mainly related to the great migrations of people to the same areas; 4) population pressure was also related to productivity decrease due to the 4 000a B.P. cold event. 4. When population pressure is formed, war is the most possible way to solve the intensions between population and the limited cultivated land and then resulted in the formation of civilization. In this way the climate change during the 4 000a B.P. cold event may have facilitated the emergence of Chinese ancient civilization. Their detailed relations could also be further understood in this way: The first birth places of China ancient civilization could be in Changjiang areas or (and) Daihai area, Shandong province rather than in central China and the emergence time of ancient civilization formed in central China should be delayed if the 4 000a B.P. cold event and companied flooding disasters didn't occurred.

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在峨眉山大火成岩省(ELIP)产出许多岩浆Cu-Ni-PGE岩浆硫化物矿床,如金宝山、杨柳坪、力马河、白马寨,以及大槽-阿布郎当矿化岩体。根据成矿元素组成特征,这些矿床可以区分为多种不同矿化类型,有以铂族元素为主贫铜镍的矿床,如金宝山Pt-Pd矿床;有含较高铂族元素和铜镍的矿床,如杨柳坪Ni-Cu-PGE矿床;也有贫铂族元素富铜镍的矿床,以力马河和白马寨Ni-Cu矿床最为典型。造成峨眉山大火成岩省中Ni-Cu-PGE岩浆硫化物矿床矿化类型变异的原因是什么?它们的母质岩浆性质如何,产生于怎样的熔融程度?既然能形成岩浆硫化物矿床,造成硫化物熔离的原因有哪些,什么因素起到了关键作用?这些矿化类型多样的Ni-Cu-PGE矿床的成矿岩浆有何差异?产生差异的原因是什么?带着这些疑问,通过借鉴国内外Ni-Cu-PGE岩浆硫化物矿床研究的经验,本文以金宝山铂钯矿、力马河镍矿及大槽-阿布郎当岩体的地球化学研究为基础,结合近几年来前人对杨柳坪,白马寨等矿床的系统研究,本文试图解决上述疑问。现在取得的主要认识有: 1) 根据成矿元素组成特征,可以把峨眉山大火成岩省中(ELIP)存在的Ni-Cu-PGE岩浆硫化物矿床分成多种不同的矿化类型,包括PGE矿床(例如金宝山Pt-Pd矿),Ni-Cu-PGE矿床(例如杨柳坪矿床),Ni-Cu矿床(例如力马河和白马寨矿床),以及弱矿化或不含矿的超镁铁质堆晶岩体(例如大槽-阿布郎当岩体)。通过对ELIP中几种类型Cu-Ni-PGE矿床成矿母岩浆的研究发现,它们均具有类似峨眉山苦橄岩的成分特征,表明母岩浆形成于较高程度的地幔部分熔融,并富集Ni和PGE。 2)硫化物熔离的多阶段性是导致矿床类型变异的一个重要因素。早期结晶矿物的分离结晶导致了金宝山母岩浆出现S的饱和,少量的浸染状硫化物被携带进入岩浆通道中发生了沉淀,继续富集PGE,形成了金宝山矿体。杨柳坪的母岩浆先发生了少量早期硫化物熔离丢失,PGE弱亏损的岩浆在后期上升过程中由于强烈的地壳混染,发生了大量硫化物熔离并发生堆积,形成杨柳坪矿体。力马河和白马寨的母岩浆在早期发生了较多的硫化物丢失,PGE强烈亏损的岩浆发生了二次以上的硫化物熔离,形成了力马河和白马寨矿体。 3) R因子(岩浆与熔离硫化物的比例)是决定ELIP中Cu-Ni-PGE矿床矿化类型变异的重要因素。金宝山矿床具有极高的R值(>10000),杨柳坪和朱布矿床具有中等的R值(2000~5000),而力马河矿床近似为在经过R=2000的硫化物熔离之后,残余岩浆再经过R=200的硫化物熔离。 4) 地壳混染程度的差异可能是造成ELIP中Ni-Cu-PGE矿床矿化类型发生变异的关键因素。金宝山矿床的地壳混染程度较低,可能主要是早期橄榄石和铬铁矿的分异结晶导致了岩浆中硫化物出现了饱和。对于大槽-阿布郎当矿化岩体,只是在岩体边缘的局部出现了硫化物熔离,可能是围岩混染造成的。对于杨柳坪Ni-Cu-PGE矿床、力马河和白马寨Ni-Cu矿床,从微量元素蛛网中明显的Nb-Ta负异常,高放射成因187Os丰度的初始Os同位素组成(γOs(t)=100~120),S同位素等反映出显著的地壳混染,因而出现大量硫化物熔离。

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泥炭是第四纪,特别是全新世以来的产物。它的形成和积累主要受控于气候,其次是地质、地貌、水文等因素。因此,泥炭形成过程中包含了大量的古气候、古环境演化信息。腐殖化度在国外早已用于古气候研究,国外学者将它作为湿度代用指标,用以恢复古湿度变迁。本文首次将之引入我国泥炭古气候研究,同时结合青藏高原的气候特点,及泥炭形成过程中温度、湿度对它的影响,赋予了泥炭腐殖化度新的气候内涵。即泥炭的腐殖化度高,指示气候温暖湿润;泥炭的腐殖化度低,指示气候干燥寒冷。本文通过对青藏高原东北部红原泥炭的腐殖化度研究,并与其它研究成果对比,得出如下结论:(1)红原泥炭腐殖化度记录了过去12000年以来当地气候干湿冷暖的变化。其气候变化大致可分为3个阶段:11.8-11.2 kaBP,气候干燥寒冷;11.2-5.5 ka BP,气候温暖湿润;5.5-0 ka BP,当地气候由早中全新世温暖湿润的气候向干燥寒冷的气候波动。红原泥炭腐殖化度记录的气候变化与高原青海湖沉积物、松西错沉积物、敦德冰芯、古里雅冰芯记录的气候变化相似,表明青藏高原12000年以来可能受同一气候系统影响,其气候变化的共同特点为干冷与暖湿交替。(2)泥炭腐殖化度记录了12000年以来印度西南季风在高原的强弱演化。新仙女木期(11.8-11.2kaBP),季风强度最弱;从11.2kaBP到10.8kaBP季风强度快速增强;在10.8ka即到5.5 ka BP,季风强度一直处于强势阶段;从5.5 ka BP开始,印度西南季风强度逐渐减弱,这期间腐殖化度同时记录了百年一千年尺度印度西南季风增强事件,但总体减弱的趋势不变。(3)泥炭腐殖化度记录的百年一千年气候突然变化事件与北大西洋浮冰事件存在遥相关。对应8次浮冰事件,红原地区气候同时变得干冷,而印度西南季风强度也减弱,这表明不但末次冰期印度西南季风与北大西洋气候密切相关,而且在全新世,这种相关性同样存在。(4)泥炭腐殖化度距平值较好的反映了西太平洋副热带高压近5000年来的活动变化。腐殖化度代用指标能很好地记录较长时间西太平洋副热带高压的变化,而对西太平洋副热带高压数十年到百年的频繁波动,则记录不明显。(5)泥炭腐殖化度时间序列的功率谱分析表明,太阳活动对红原地区气.候演化有重要影响,同时太阳活动通过影响全球水循环,进而驱动温盐环流的变化,进一步影响全球气候变化。(6)泥炭腐殖化度能同时记录温度、湿度的变化,并且测定方法简便、快捷,值得进一步研究。

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The research objectives were to investigate the psychological structure of employees' organizational commitments(OCs), and its antecedents, and to examine the relative effects of employees' OCs to their performances. In order to deeply uncover the nature of OCs, some standard methods, such as in-depth interview, focus-group, semi-open questionnaire, standard questionnaire etc., were employed. In data analysis, not only some common statistical methods, such as multivariate analysis of variance, cross-table analysis, factor analysis, but also some forefront ones, such as confirmatory factor analysis and path analysis of SEM, were used. The paper covers six chapters: 1) In the first chapter, Firstly some previous empirical studies, which examined structures, antecedents, correlates, and/or consequences of organizational commitment in China and Western countries, were summarized. This summary covers most of the respectable researchers' works of this field, such as H.S.Becker, B.Buchanan, L.W.Porter, G. Ritzer, H.M.Trice, J.A.Alutto, L.G.Hrebiniak, R.T.Mowday, J.P.Meyer, N.J.Allen, G.W.McGee, R.C.Ford, R.Eisenberger, etc. Then three theoretical hypothesis were put forward as following: ① In China, OCs should be multidimensional psychological structures, which means there should exist more than one type of OCs; ② There should be some different antecedents to different OCs; ③ Employees with different types of OC should perform differently in their works. Finally the theoretical and practical significance were discussed. 2) In the second chapter, great efforts were made to investigate the OC types. Firstly, in-depth interview with managers and employees, semi-open questionnaire, and some other methods were used in the pilot research to gather much qualitative material. Then OC questionnaire was designed to get quantitative data in about 20 enterprises, including state-owned, collective-owned, wholly foreign-funded, and joint-ventures. During revising of this questionnaire, there were about 5000 samples surveyed. after factor analysis, the data shows that there should be 5 types of OCs in China, which were respectively named as Affective Commitment, Normative commitment, Ideal Commitment, Economic Commitment, Choice Commitment. Thirdly, confirmatory factor analysis method was used to successfully confirm this 5-factor model. Finally, Cronbach a and test-retest correlate indicate that this questionnaire is reliable. Since factor analysis result has show its construct validity, a simple criterion-related validity research was conducted. 3) In order to investigate the correlation between different OC and employee performance and different antecedents of OC, 5 other questionnaires, such as Employee Satisfaction Questionnaire, Perceived Organizational Support Questionnaire, Social Exchange Questionnaire, Altruism Scale, and Leader Confidence Scale were revised in the third chapter. 4)In the fourth chapter, a lot of correlates, cross-table analysis were conducted to show the correlation between different OCs and 10 performances, which indicate employees with different OCs will show different performance in 10 variables, such as altruism, etc. 5) In the fifth chapter, correlate analysis, multivariate of analysis, and path analysis of SEM were used to investigate the antecedents of OC. A satisfactory model showing the correlation between OC and their antecedents was confirmed. 6) In the last chapter, all researches about OC, and its limitations were summarized.