首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 13 毫秒
1.
The option of weighting impact categories according to ISO 14042 on Life Cycle Impact Assessment (LCIA) is particularly difficult for global organizations, as they have to consider a wide range of values. The motivation for employing weighting is usually based on the desire to simplify LCIA output, especially in circumstances where product system tradeoffs occur. Looking globally at regional variations in legislation, consumer values, monetary valuation, existing weighting sets and expert opinions, no globally agreed upon weighting set is likely to be derived. This is due to both the inherent subjectivity of weighting and local variations in environmental imperatives. Hence, the authors recommend that LCIA quantitative weighting, especially those provided in pre-packaged software instruments, should not be employed. Admittedly, to use a spectrum of LCIA results for internal design decisions, some kind of tradeoff analysis has to be performed, especially if comparing competing design alternatives. However, this trade-off analysis should be done separately from the technical LCA study and should reflect values and visions of the global organization, as well as the circumstances of the targeted market, in a qualitative way. For any external communication, none of the quantitative weighting sets can be used.  相似文献   

2.
中国松杉类植物濒危等级划分的比较   总被引:19,自引:0,他引:19  
本文根据世界保护监测中心(WCMC)和国际松杉类植物专家(CSG)编制的濒危植物名录,以及中国植物红皮书(第1卷)列出中国受威胁松杉类植物共141种及变种。通过对上述三者濒危等级的比较表明,它们在中国松杉类植物濒危等级的划分上并不完全一致,主要原因是划分物种濒危等级的标准不同或资料依据不完全等。最后,作者根据1994年IUCN提出的物种受威胁等级划分标准草案(2.3版本),对中国松杉类一些濒危种类的等级划分作了初步分析和讨论。  相似文献   

3.
Germination of barley is accompanied by changes in water-soluble seed proteins. 2-DE was used to describe spatio-temporal proteome differences in dissected seed tissues associated with germination and the subsequent radicle elongation. Protein identification by MS enabled assignment of proteins and functions to the seed embryo, aleurone, and endosperm. Abundance in 2-DE patterns was monitored for 48 different proteins appearing in 79 gel spots at 8 time-points up to 72 h post imbibition (PI). In embryo, a beta-type proteasome subunit and a heat shock protein 70 fragment were among the earliest proteins to appear (at 4 h PI). Other early changes were observed that affected spots containing desiccation stress-associated late embryogenesis abundant and abscisic acid (ABA)-induced proteins. From 12 h PI proteins characteristic for desiccation stress disappeared rapidly, as did a putative embryonic protein and an ABA-induced protein, suggesting that these proteins are also involved in desiccation stress. Several redox-related proteins differed in spatio-temporal patterns at the end of germination and onset of radicle elongation. Notably, ascorbate peroxidase that was observed only in the embryo, increased in abundance at 36 h PI. The surprisingly early changes seen in the protein profiles already 4 h after imbibition indicate that germination is programmed during seed maturation.  相似文献   

4.
Phenice (Am J Phys Anthropol 30 (1969):297–301) reported a success rate of 96% for his method of sex determination based on three morphological features of the pelvis. Numerous studies have tested and evaluated the method with affirmative results. The results of the study by MacLaughlin and Bruce (J Forensic Sci 35 (1990):1384–1392) were inconsistent with other studies, reporting far lower rates of accuracy and a greater degree of interobserver error. The authors believe that this may be the result of the inclusion of an “ambiguous” classification category. Revised modelling using forced classification of sex provides much higher classification rates with the implication that the poor results reported by MacLaughlin and Bruce were due to methodological error for the most part. Am J Phys Anthropol 159:182–183, 2016. © 2015 Wiley Periodicals, Inc.  相似文献   

5.
In this article, we describe a conditional score test for detecting a monotone dose‐response relationship with ordinal response data. We consider three different versions of this test: asymptotic, conditional exact, and mid‐P conditional score test. Exact and asymptotic power formulae based on these tests will be studied. Asymptotic sample size formulae based on the asymptotic conditional score test will be derived. The proposed formulae are applied to a vaccination study and a developmental toxicity study for illustrative purposes. Actual significance level and exact power properties of these tests are compared in a small empirical study. The mid‐P conditional score test is observed to be the most powerful test with actual significance level close to the pre‐specified nominal level.  相似文献   

6.
To assess the pollen hosts of 60 western palaearctic bee species of the genus Colletes (Colletidae), we microscopically analysed 1336 pollen loads of collected females. Twenty‐six species (43.3%) were found to be specialized at the level of plant family, subfamily or genus. Thirty‐four species (56.7%) proved to be pollen generalists to varying degrees, visiting the flowers of up to 15 different plant families. Flowers of the subfamily Asteroideae (Asteraceae) are by far the most important pollen source, contributing 23.6% to the pollen‐plant spectrum of the whole bee genus. The high significance of Asteroideae pollen is due to the large number of specialists: 14 Colletes species belonging to four different taxonomic groups harvest pollen exclusively or predominantly on flowers of the Asteroideae. By striking contrast, Asteroideae pollen plays only a marginal role in the diets of the pollen generalists: it was recorded in only 2.7% of the pollen loads and in seven out of the 34 pollen generalists. Among the few generalists exploiting Asteroideae for pollen, three closely related species have ancestors which were possibly specialized on Asteraceae. The pattern of use of Asteroideae pollen by the Colletes bees supports recent findings that this pollen possesses unfavourable or protective properties, which render its digestion difficult, and suggests that bees need physiological adaptations to successfully utilize it. © 2008 The Linnean Society of London, Biological Journal of the Linnean Society, 2008, 95 , 719–733.  相似文献   

7.
Hamer  M.L.  Brendonck  L. 《Hydrobiologia》1997,359(1-3):1-12
Southern Africa is defined here as Africa south of the Zambezi and Kunene Rivers. Here, annual average rainfall, rainfall season, and effective temperature are climatic factors which influence anostracan distribution. The type of temporary pool also appears to have some effect on distribution. Areas of high species richness are not confined to any particular climatic region and such areas occur in arid, montane and subtropical regions of southern Africa. Forty-six anostracan species have been recorded from the subcontinent and 80% of these are endemic. IUCN Red Data assessment of species revealed that two species can be considered 'Critically Endangered', while a further four are 'Endangered', and three are 'Vulnerable'. Many parts of southern Africa have been inadequately sampled but in South Africa, where the anostracans are relatively well known, temporary pool inhabitants are threatened mainly by agriculture, urbanization, pollution and pesticides. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

8.
The learned songs of songbirds often cluster into population-wide types. Here, we test the hypothesis that male and female receivers respond differently to songs depending on how typical of those types they are. We used computational methods to cluster a large sample of swamp sparrow (Melospiza georgiana) songs into types and to estimate the degree to which individual song exemplars are typical of these types. We then played exemplars to male and female receivers. Territorial males responded more aggressively and captive females performed more sexual displays in response to songs that are highly typical than to songs that are less typical. Previous studies have demonstrated that songbirds distinguish song types that are typical for their species, or for their population, from those that are not. Our results show that swamp sparrows also discriminate typical from less typical exemplars within learned song-type categories. In addition, our results suggest that more typical versions of song types function better, at least in male–female communication. This finding is consistent with the hypothesis that syllable type typicality serves as a proxy for the assessment of song learning accuracy.  相似文献   

9.
For tropical forest restoration to result in long‐term biodiversity gains, native trees must establish self‐sustaining populations in degraded sites. While many have asked how seedling recruitment varies between restoration treatments, the long‐term fate of these recruits remains unknown. We address this research gap by tracking natural recruits of 27 species during the first 7 years of a tropical forest restoration experiment that included both planted and naturally regenerating plots. We used an individual‐based model to estimate the probability that a seedling achieves reproductive maturity after several years of growth and survival. We found an advantage for recruits in naturally regenerating plots, with up to 40% increased probability of reproduction in this treatment, relative to planted plots. The demographic advantage of natural regeneration was highest for mid‐successional species, with relatively minor differences between treatments for early‐successional species. Our research demonstrates the consequences of restoration decision making across the life cycle of tropical tree species.  相似文献   

10.
Locomotor diversity among lemurids has been ignored by placing most species into a category of arboreal quadrupeds. Recent field studies have shown that leaping behaviors comprise a relatively large amount of their travel. In this contribution I detail a study of captive lemurs locomoting on a designed support network and/or in outdoor enclosures. Associations between support context, leaping behaviors, and landing kinematics are detailed for Hapalemur griseus, Eulemur rubriventer, Eulemur fulvus, Eulemur mongoz, and Varecia variegata. In-air body position, including the amount and location of trunk flexion, coupled with the extent of shoulder and hip flexion dictates limb use at landing. Limb strike pattern when landing onto the same support type varies interspecifically. The kinematic variation in leaping behaviors may well have implications for functional analyses of the postcranium. © 1996 Wiley-Liss, Inc.  相似文献   

11.
自2019年末,新冠肺炎的全球大流行使蝙蝠(翼手目动物)倍受关注,甚至人们“谈蝠色变”。蝙蝠在生态和分类上多样性极高,占哺乳动物种类的20%左右。蝙蝠不仅在害虫控制、种子传播、植物授粉等方面具有重要的生态作用和经济价值,也在健康长寿、生物仿生和语言进化等方面具有重要的科研价值。中国是全世界蝙蝠物种多样性最丰富的国家之一,已知的物种超过了140种。近几十年来,中国学者在蝙蝠分类学、生态学、行为学、进化生物学、神经生物学和病毒病源学等研究领域取得了丰硕的成果,然而涉及蝙蝠的生态系统服务和资源保护的相关研究比较少。由于生境退化、过度捕杀、栖息地破坏、城市化、杀虫剂使用、气候变化等原因,中国蝙蝠受到极大的威胁,约51%的物种位于近危等级之上。为了有效地保护中国蝙蝠物种的多样性,建议加强基础研究,建立中国蝙蝠多样性监测网络,加强蝙蝠栖息地保护,完善相关法律法规,加强蝙蝠公众教育,以促进中国蝙蝠生物学研究和保护。  相似文献   

12.
The paper offers comments arising from the author's experience as a practising taxonomist on two aspects of what is often called the species problem: the reality of species and species as individuals. Three different meanings of reality are distinguished and discussed in this context: mental reality, biological reality and evolutionary reality. The author holds the view that, on all three definitions, species must be judged to be real. On the argument concerning species as individuals, the opinions ofHull, Ghiselin and others are carefully presented but rejected by the author, who retains the belief that species are classes and not individuals.Dedicated to the memory of JohnS. L. Gilmour.  相似文献   

13.
Conifers (the fast-growing softwoods of the world) occur as the dominant plants of most temperate rainforest communities. Almost all are tall forest trees, whose high commercial value creates conservation vulnerability for many local species in our increasingly resource-hungry world. Counting species, of an estimated 600 world total 362 would fall into this category and consequently appear on this list. This paper provides a preliminary analytical world census list of 416 conifer taxa (species, subspecies and varieties) considered to be of conservation concern.  相似文献   

14.
李玉凤  刘红玉  郑囡  曹晓 《生态学报》2011,31(4):1021-1028
以西溪国家湿地公园为研究案例,从景观功能分类入手,揭示城市湿地公园景观格局与功能特征。结果表明:(1)西溪湿地公园是以生态保护为主,兼顾合理利用为基本功能特征,其生态保护功能区面积占整个公园的53.7%,旅游休闲区面积占46.3%;(2)西溪湿地公园生态保护功能斑块在整个公园中所占面积为42.08%,且面积大、形状复杂、多样性较低;旅游休闲斑块面积占25.41%,并且表现为斑块面积小、形状规则、多样性高等特点;(3)西溪湿地公园生态保护廊道面积是旅游休闲廊道面积的一半左右,其网络结构比旅游休闲廊道复杂,有利于生态保护功能的发挥;(4)生态保护廊道缓冲区内主要由生态保护斑块组成,旅游休闲廊道的缓冲区内生态功能斑块和旅游休闲斑块所占面积相差不大。基于功能分类的景观格局研究方法有利于识别景观功能的空间特征,能够有效揭示景观生态保护与利用的空间关系。  相似文献   

15.
ABSTRACT

This article treats the pairing of “transgender” and “transracial” in the intertwined discussion of Caitlyn Jenner and Rachel Dolezal as an intellectual opportunity rather than a political provocation. I situate the Dolezal affair in the context of the massive destabilization of long taken-for-granted categorical frameworks, which has significantly enlarged the scope for choice and self-fashioning in the domains of race, ethnicity, sex, gender, and sexuality. Anxieties about opportunistic, exploitative, or fraudulent identity claims have generated efforts to “police” unorthodox claims – as well as efforts to defend such claims against policing – in the name of authentic, objective, and unchosen identities. Instead of a shift from given to chosen identities, as posited by theories of reflexive modernity, we see a sharpened tension between idioms of choice, autonomy, subjectivity, and self-fashioning on the one hand and idioms of givenness, essence, objectivity, and nature on the other.  相似文献   

16.
The leafy spurges, Euphorbia subgenus Esula, have one of their diversity centres in the Mediterranean, which is considered to be one of the 25 biodiversity hot‐spots. The eastern Mediterranean, in particular, is characterized by its high species richness and is therefore considered to be a cradle for lineage diversification. However, the area remains neglected in phylogenetic studies. Using nuclear ribosomal internal transcribed spacer (ITS) and plastid trnTtrnF sequences, we explored the phylogenetic relationships in the predominantly eastern Mediterranean E. hierosolymitana group, which is characterized by a woody habit. The widespread shrublets E. acanthothamnos, E. glabriflora and E. spinosa, which are similar in habit, are not most closely related, the last two forming a sister clade to other taxa. From the E. acanthothamnos alliance, dendroid shrubs evolved at least two, but possibly four, times, giving rise to widespread E. bivonae and E. hierosolymitana, the Cretan endemic E. sultan‐hassei and the here newly described and genetically most divergent E . lemesiana , endemic to Cyprus. We provide a taxonomic treatment and morphological comparison with the similar, but not most closely related, E. hierosolymitana. Our study underlines the phytogeographical peculiarity of Cyprus and contributes to our current knowledge on the diversification patterns in the eastern Mediterranean. © 2015 The Linnean Society of London, Botanical Journal of the Linnean Society, 2015, 179 , 295–307.  相似文献   

17.
The history of the deme terminology is outlined,John Gilmour's leading role in inventing and publicising it is explained, and its relative failure discussed. The rather different reactions of zoologists and botanists to advocacy of the terminology byGilmour and others are described and some explanation of these differences is attempted. A limited use of first-order deme terms, especially gamodeme, topodeme and cytodeme, is advocated as being a reasonable and practical procedure.Dedicated to the memory of JohnS. L. Gilmour.  相似文献   

18.
We compared the abundance of litter categories (coarse particulate organic matter 1–16 mm, leaves >16 mm, and small woody detritus 16–100 mm) and macroinvertebrate assemblages between natural litter patches in pools and riffles in a headwater stream. Litter patches in pools were formed under conditions of almost no current (<6 cm s−1), but in riffles they were formed under variable current velocities (13–89 cm s−1). Although the abundance of each litter category exhibited seasonal change, leaves were more abundant in riffles, and coarse particulate organic matter and small woody detritus were more abundant in pools throughout the study period. Macroinvertebrate assemblages in pools and riffles also changed seasonally but distinctly differed from each other. Shredders, collector-gatherers, and predators were the dominant functional groups in abundance in both pools and riffles, but the dominant shredders were caddisflies in pools and stoneflies in riffles. It is considered that the hydraulic conditions affected macroinvertebrate assemblages directly and indirectly through influences on the characteristics of litter retained in the patches. Our results suggest that the relative abundance of litter patches in pools and riffles largely affects the macroinvertebrate community structure of the headwater stream. Received: July 19, 2001 / Accepted: December 19, 2001  相似文献   

19.
The usual definitions of sensitivity, specificity and predictive value of a diagnostic test T refer only to the situation of the presence or absence of disease. There is then question of the appropriate extensions of these definitions in cases where there are more than two diagnostic categories, especially with ordered or graded responses. This paper deals with some aspects of this problem. An example with the data of BERGESON and STEINFELD (1974) on gradings of fever in children by palpation is analyzed, using the methods discussed in this paper.  相似文献   

20.
A survey into the practice of fine needle aspiration cytology of the breast amongst members of the British Society for Clinical Cytology in 1990 and 1991 was performed. This paper presents their reported use of diagnostic categories in reporting and the criteria found useful in the diagnosis of benign and malignant disease. A wide variety of diagnostic categories are in use. the criteria used in diagnosis largely follow recommendations found in standard textbooks, but some less well recognized features were also suggested.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号