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1.
研究了不同生境条件下喜树和南方红豆杉混交群落中喜树和南方红豆杉的生活史型谱特征。结果表明,喜树和南方红豆杉在S生活史型得分和比例均为0。喜树和南方红豆杉生活史型V主成分得分均以山地2最高,而纯林的生活史型V主成分得分最低,C也表现为山地2最高,而纯林最低。喜树种群的生活史型比例按照从山地、坡地、平地、纯林排序,V型比例逐渐上升而C型比例逐渐下降的趋势,这就构成了混交群落中喜树种群的生活史型谱。南方红豆杉种群的生活史型谱特征,主要表现为山地2和坡地V型比例最小,而C型比例最大,纯林种植中V型比例较高,而以纯林1的V型比例最高,C型比例最小。  相似文献   

2.

A new definition of life is proposed and discussed in the present article. It is formulated by modifying and extending NASA’s working definition of life, which postulates that life is a “self-sustaining chemical system capable of Darwinian evolution”. The new definition includes a thermodynamical aspect of life as a far from equilibrium system and considers the flow of information from the environment to the living system. In our derivation of the definition of life we have assumed the hypothesis, that during the emergence of life evolution had to first involve autocatalytic systems that only subsequently acquired the capacity of genetic heredity. The new proposed definition of life is independent of the mode of evolution, regardless of whether Lamarckian or Darwinian evolution operated at the origins of life and throughout evolutionary history. The new definition of life presented herein is formulated in a minimal manner and it is general enough that it does not distinguish between individual (metabolic) network and the collective (ecological) one. The newly proposed definition of life may be of interest for astrobiology, research into the origins of life or for efforts to produce synthetic or artificial life, and it furthermore may also have implications in the cognitive and computer sciences.

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3.
郭泉水  江洪  王兵  阎洪 《生态学报》1999,19(4):573-577
采用C.Raunkiaer的生活型分类系统,对我国主要森林群落的生活谱资料进行整理,编制了全国划分标准统一的植被生活型谱,并应用聚类分析方法,对植物生活型谱进行数量分类,在此基础生态信息系统(GREEN)和地理信息系统(IDRISI)等现代信息处理技术,定义各谱系的生态气候适应参数区间,模拟并图象显示各类植物生活型谱在地理空间上的分布格局,通过聚类分析,将我国主要木 落的植物生活型谱划分了11种类  相似文献   

4.
改进实验种群生命表编制的方法——以黑肩绿盔盲蝽为例   总被引:5,自引:2,他引:3  
刘家莉  杨斌  陆永跃  黄寿山 《生态学报》2009,29(6):3206-3212
采用指形管单头饲养的方法,编制了稻飞虱的重要捕食性天敌黑肩绿盔盲蝽取食替代寄主米蛾卵的实验种群生命表.通过直接统计和加权平均2种方法的对比,推导出各虫龄历期的计算公式.针对特定时间生命表和特定年龄生命表两种编制方法中存在的不足进行了分析,并提出了可行的解决办法,即在特定时间生命表中导入幼期存活率,在特定年龄生命表中根据推导出的历期公式计算各个虫龄的历期,得到世代平均历期T(T=∑tx+tA ),进而得到rm值.通过对两种生命表编制方法的完善,为昆虫实验种群生命表的编制和参数的计算提供了方便和完整的计算方法.  相似文献   

5.
由于生命科学研究的复杂性,以及系统生物学的面向多个生物学水平进行研究的特点,对大规模、分布式应用资源进行整合是生命科学信息资源建设中面临的主要问题,分布式技术的应用使生物信息资源建设实现了高度的自动化,并行化。本文对分布式集成技术在生物学领域的应用和未来发展做了简要综述。并结合当今技术趋势给出了生物信息学项目进行分布式资源整合的解决方案。  相似文献   

6.
近几年来,肺癌的发病率呈现逐年上升的趋势,成为癌症中的头号杀手。临床上针对不同类型肺癌有不同的治疗策略,由于临床上大部分病人在确诊为肺癌时已经为晚期,对于常规治疗方法难以达到效果时,关注肺癌患者的生存质量就显地尤为必要。肺癌生存质量量表可以反映病人临床治疗后的生存质量状况,达到反馈治疗效果的目的。在临床实验中使用肺癌生存质量量表可以帮助临床医师制定最优化的治疗方案。国际上的研究大多不是以生存质量为主要终点的研究,生存质量也不能全面的反映病人预后的状况,希望在今后的研究中,肺癌生存质量量表能够在临床中的使用更加普及、更加全面。本文就肺癌生存质量量表在晚期肺癌中使用的研究进展作一综述,以期更加促进我们对于晚期肺癌患者生存质量的思考与关注,更有利于适合我国国情的生存质量量表的研究和发展。  相似文献   

7.
D K Bozhkov 《Parazitologiia》1976,10(5):428-433
On the basis of the analysis of regularities accompanying the secondary simplification of the life cycles of helminths on account of the reduction in the number of the animals-hosts 8 rules have been formulated. They are based on the following important regularities. 1. At the secondary simplification of the life cycles of helminths never fall out the first intermediate host in Trematoda and the definitive host in Nematoda. This phenomenon is suggested to be called "the host stability in the life cycle". 2. Mostly often from the life cycles fall secondarily out those hosts which join in the life cycle at its first complication later. 3. The phase of the helminth having transformed into a parasitic form at the first complication of its life cycle remains the same at the secondary simplification of this cycle.  相似文献   

8.
摘要 目的:探讨左心耳封堵术(LAAC)术后对房颤(AF)患者的生活质量的影响,并分析其影响因素。方法:回顾性分析兰州大学第二医院2019年3月至2022年3月期间接受LAAC治疗的213例AF患者的临床资料。根据简明健康调查量表(SF-36)将213例LAAC术后AF患者分为低生活质量组(总分≤50分,n=107)和高生活质量组(总分>50分,n=106)。收集并比较AF患者术前基线资料、实验室资料和影像学资料。采用多因素Logistic回归模型分析LAAC术后AF患者生活质量的影响因素。结果:低生活质量组心房颤动血栓发生危险度(CHA2DS2-VASc)评分高于高生活质量组(P<0.05)。低生活质量组的凝血酶原时间百分比高于高生活质量组(P<0.05)。高生活质量组红细胞水平高于低生活质量组(P<0.05)。高生活质量组的左心室射血分数(LVEF)高于低生活质量组(P<0.05)。多因素Logistic回归分析结果显示:CHA2DS2-VASc评分偏高、LVEF偏低是影响LAAC术后AF患者生活质量的危险因素(P<0.05)。结论:CHA2DS2-VASc评分偏高、LVEF偏低是影响LAAC术后AF患者生活质量的危险因素,可降低LAAC术后AF患者的生活质量。  相似文献   

9.
The relative species variety as a ratio of the species number known from the territory north of the polar circle and the species number in eastern Europe as a whole has been calculated for subgenera and life forms of Lymnaeidae. The largest value of this feature is a specific parameter for ampla-like life forms. The domination of one life form is a result of its adaptation for both life in places with wave activity and water respiration. The relatively high species variety of the subgenera Lymnaea and Peregriana is related to domination of the ampla-like life form arranged by the mentioned taxons.  相似文献   

10.
缙云山常绿阔叶林不同演替阶段植物生活型谱比较研究   总被引:9,自引:0,他引:9  
采用Raunkiner生活型分类系统,对缙云山常绿阔叶林不同演替阶段植物的生活型进行统计,编制了生活型谱,并与其他亚热带地区常绿阔叶林相比较。结果表明,缙云山植被属典型的中亚热带常绿阔叶林植被,高位芽植物占绝对优势,达80%以上,其中小高位芽植物最多,中高位芽与矮高位芽植物次之,藤本植物较丰富。缙云山不同演替阶段的植物的生活型谱不同。随着进展演替阶段的逐渐更替,高位芽植物的比例呈递增趋势,地面芽植物、地下芽植物成分有所减少。高位芽的常绿树种会逐渐代替针叶树种。  相似文献   

11.
Functional Morphology of Stylophoran Echinoderms   总被引:4,自引:1,他引:3  
The life orientation and mode of life of stylophorans are a subject of much ongoing debate. Examination of the ornamentation occurring both on the arm and theca in several cornutes and mitrates strongly supports the view that the life orientation was similar in all stylophorans and was ‘flat‐surface down’. The presence of an asymmetrical ornamentation adapted to hinder, or minimize, back slippage of the organism in all stylophorans gives strong support to their interpretation as mostly sessile organisms, feeding with the arm facing the current and the theca downstream. The examination of a wide array of thecal morphologies and sculpture patterns displayed by the various groups of cornutes and mitrates allows the identification of three main modes of life in stylophorans: (1) an epibenthic mode of life, with the theca as main anchor to the substrate (e.g. asymmetrical cornutes, Diamphidiocystis); (2) an epibenthic mode of life, with the arm as main anchor to the sediment (e.g. symmetrical cornutes, Peltocystis, primitive Mitrocystitida, some Kirkocystidae); (3) an infaunal mode of life, with the theca buried in a slightly inclined attitude (e.g. some Kirkocystidae, Mitrocystitida with cuesta‐shaped ribs). The partially buried mode of life of Lagynocystis is intermediate between 2 and 3.  相似文献   

12.
A correlation is known to exist in yeast and other organisms between the cellular resistance to stress and the life span. The aim of this study was to examine whether stress treatment does affect the generative life span of yeast cells. Both heat shock (38 degrees C, 30 min) and osmotic stress (0.3 M NaCl, 1 h) applied cyclically were found to increase the mean and maximum life span of Saccharomyces cerevisiae. Both effects were more pronounced in superoxide dismutase-deficient yeast strains (up to 50% prolongation of mean life span and up to 30% prolongation of maximum life span) than in their wild-type counterparts. These data point to the importance of the antioxidant barrier in the stress-induced prolongation of yeast life span.  相似文献   

13.
Richardson J 《Bioethics》1987,1(3):226-240
The author, an economist, rebuts the contention that human life cannot and should not be economically evaluated and argues that such evaluations are made implicitly and inconsistently, resulting in a reduction of human welfare. He presents an economic framework for the analysis of costs and benefits in which the focal point, as in most value systems, is the tradeoff between life and quality of life. Therefore, as the quality of life decreases, society's efforts to preserve life should decrease. If the valuation of life includes self evaluation, then there should be less effort to preserve the life of an individual who wishes to die. Richardson concludes that voluntary euthanasia is a limiting case in which society accepts the individual's valuation of life.  相似文献   

14.
植物生活史型的划分及其相互转化   总被引:5,自引:6,他引:5  
基于环境条件的变化,分析了植物在完成生活史过程中,营养生长、克隆生殖和有性生殖过程的权衡的结果直接导致的植物生活史型形成以及相互转化过程。根据胁迫和扰动程度将植物的生境划分为基本生境型、特殊过渡型和过渡型,其中过渡型(EDF)在自然界中具有普遍意义;与生境过渡型(EDF)相对应,植物形成的生活史型也为过渡生活史型(VCS),其基本型V、C和S以及特殊过渡型VC、VS和CS是其特例。植物的生活史型过渡型(VCS)具有普适性意义,在生境调控下的任一种植物生活史型均可表示为Vx1Cx2Sx3。植物生活史型的相互转化与其生境类型的相互转变是完全对应的,这种相互转化的过程和途径是复杂的,且具有可逆性的特点。  相似文献   

15.
The Moon and the Earth were bombarded heavily by planetesimals and asteroids that were capable of interfering with chemical evolution and the origin of life. In this paper, we explore the frequency of giant terrestrial impacts able to stop prebiotic chemistry in the probable regions of chemical evolution. The limited time available between impacts disruptive to prebiotic chemistry at the time of the oldest evidence of life suggests the need for a rapid process for chemical evolution of life. The classical hypothesis for the origin of life through the slow accumulation of prebiotic reactants in the primordial soup in the entire ocean may not be consistent with constraints imposed by the impact history of Earth. On the other hand, rapid chemical evolution in cloud systems and lakes or other shallow evaporating water bodies would have been possible because reactants could have been concentrated and polymerized rapidly in this environment. Thus, life probably could have originated near the surface between frequent surface sterilizing impacts. There may not have been continuity of life depending on sunlight because there is evidence that life, existing as early as 3.8 Gyr ago, may have been destroyed by giant impacts. The first such organisms on Earth where probably not the ancestors of present life.  相似文献   

16.
Mark T. Brown 《Bioethics》2019,33(9):1035-1041
The somatic integration definition of life is familiar from the debate on the determination of death, with some bioethicists arguing that it supports brain death while others argue that some brain‐dead bodies exhibit sufficient somatic integration for biological life. I argue that on either interpretation, the somatic integration definition of life implies that neither the preimplantation embryo nor the postimplantation embryo meet the somatic integration threshold condition for organismal human life. The earliest point at which a somatic integration determination of life could be made would be the beginning of the fetal stage, 9 weeks postfertilization. Bioethical implications are considered, specifically with respect to the moral status of the postimplantation embryo in embryo research and abortion.  相似文献   

17.
目的:探讨食管癌传统开胸手术中不同术式对术后长期生活质量(QOL)影响。方法:回顾性调查2010年4月1日至2011年4月1日在我科例行传统开胸手术颈部吻合和胸内吻合的160食管癌患者,将其分为两组,A组:颈部吻合手术;B组:胸内吻合手术。采用生活质量测定量表核心量表(QLQ-C30),对其术前和术后3,6和12个月的QLQ-C30得分与参考值进行比较。结果:术后情绪功能,体力功能显着下降;症状方面,术后呼吸困难,疼痛明显加重;术后第3个月疲乏及经济困难明显加重;术后第12个月起,经济困难状况好转,较术前无明显差异;术后颈部吻合手术组较胸内吻合手术组在体力功能、角色功能、情绪功能及总体状况显著的降低;症状方面,颈部吻合手术组较胸内吻合手术组,术后疲乏显著升高,呼吸困难术后显著升高直至术后第12个月才基本恢复,无统计学差异。结论:术后生活质量与术前比较,颈部吻合对患者生活质量影响明显。比较两种方法,颈部吻合患者较胸内吻合患者术后长期生活质量下降明显。  相似文献   

18.
This article proposes new terminology that distinguishes between different concepts involved in the discussion of the shelf life of pharmaceutical products. Such comprehensive and common language is currently lacking from various guidelines, which confuses implementation and impedes comparisons of different methodologies. The five new terms that are necessary for a coherent discussion of shelf life are: true shelf life, estimated shelf life, supported shelf life, maximum shelf life, and labeled shelf life. These concepts are already in use, but not named as such. The article discusses various levels of "product" on which different stakeholders tend to focus (e.g., a single-dosage unit, a batch, a production process, etc.). The article also highlights a key missing element in the discussion of shelf life-a Quality Statement, which defines the quality standard for all key stakeholders. Arguments are presented that for regulatory and statistical reasons the true product shelf life should be defined in terms of a suitably small quantile (e.g., fifth) of the distribution of batch shelf lives. The choice of quantile translates to an upper bound on the probability that a randomly selected batch will be nonconforming when tested at the storage time defined by the labeled shelf life. For this strategy, a random-batch model is required. This approach, unlike a fixed-batch model, allows estimation of both within- and between-batch variability, and allows inferences to be made about the entire production process. This work was conducted by the Stability Shelf Life Working Group of the Product Quality Research Institute.  相似文献   

19.
Abstract. Historically, characters from early animal development have been a potentially rich source of phylogenetic information, but many traits associated with the gametes and larval stages of animals with complex life cycles are widely suspected to have evolved frequent convergent similarities. Such convergences will confound true phylogenetic relationships. We compared phylogenetic inferences based on early life history traits with those from mitochondrial DNA sequences for sea stars in the genera Asterina, Cryptasterina , and Patiriella (Valvatida: Asterinidae). Analysis of these two character sets produced phylogenies that shared few clades. We quantified the degree of homoplasy in each character set when mapped onto the phylogeny inferred from the alternative characters. The incongruence between early life history and nucleotide characters implies more homoplasy in the life history character set. We suggest that the early life history traits in this case are most likely to be misleading as phylogenetic characters because simple adaptive models predict convergence in early life histories. We show that adding early life history characters may slightly improve a phylogeny based on nucleotide sequences, but adding nucleotide characters may be critically important to improving inferences from phylogenies based on early life history characters.  相似文献   

20.
目的:探讨慢性心力衰竭(CHF)患者生活质量与社会支持的关系及其影响因素。方法:选取我院于2019年1月~2020年5月期间收治的230例CHF患者纳入研究组,选取同期来我院行常规心血管体检的健康志愿者100例作为对照组。采用明尼苏达州心力衰竭生活质量问卷(MLHFQ)评价两组生活质量,选用社会支持评定量表对两组的社会支持进行评价。采用Pearson相关性分析CHF患者生活质量与社会支持的相关性,采用单因素以及多因素Logistic回归分析CHF患者的生活质量的影响因素。结果:研究组的症状、体力、情绪、社会经济、总分均高于对照组(P0.05)。研究组客观支持、个体对支持的利用度、主观支持、总分均高于对照组(P0.05)。Pearson相关性分析结果表明,CHF患者生活质量总分与社会支持总分呈正相关(P0.05)。单因素分析结果可知,CHF患者生活质量与年龄、性别、文化程度、日常生活能力、病程、心功能分级、主要照顾者身份、照顾者健康状况有关(P0.05),而与婚姻状况、居住情况无关(P0.05)。多因素Logistic回归分析结果显示:年龄、文化程度、日常生活能力、主要照顾者身份及照顾者健康状况为CHF患者生活质量的影响因素(P0.05)。结论:CHF患者的生活质量与社会支持密切相关,且年龄、文化程度、日常生活能力、主要照顾者身份及照顾者健康状况为CHF患者生活质量的影响因素,临床医护人员应采取有针对性的干预措施以提高CHF患者的生活质量。  相似文献   

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