共查询到20条相似文献,搜索用时 15 毫秒
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Some basic fallacies in the computation of the paternity index have been pointed out. The general finding that the true fathers' mean paternity index is greater than that of nonfathers is a necessary consequence of an algebraic identity, having nothing to do with paternity or nonpaternity. It has also been shown that the paternity index is not a likelihood ratio as claimed. The fact that a paternity index may frequently take values less than unity leads to absurd conclusions regarding the probability of paternity. A formula relating prior and posterior probabilities of paternity, based solely on genetic marker testing results (exclusion or nonexclusion), is reiterated as a substitute for the current paternity index. 相似文献
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海南万宁青皮林群落多样性特征研究 总被引:8,自引:0,他引:8
根据样方调查,对海南万宁青皮林群落的种类组成、外貌、结构特征和物种多样性进行分析。结果表明:(1)海南万宁青皮林自然保护区有维管植物137种,隶属于62科110属,其中热带性分布种达95.5%,群落属于热带雨林植被类型中的海岸单优青皮群落。(2)群落的优势种为青皮,外貌常绿,生活型以小高位芽为主(占35.04%),青皮种群表现为增长趋势。(3)群落的物种丰富度Magarlef指数为34.30,Shannon-Wienner指数为2.31,Simpson指数为0.99,均匀度Pielou指数为1.08。(4)群落各层次的丰富度表现为乔木层>灌木层>藤本植物>草本层,Simpson指数表现为灌木层>草本层>藤本植物>乔木层,Shannon-Wienner指数表现为灌木层>藤本植物>草本层>乔木层,均匀度表现为草本层>灌木层>藤本植物>乔木层,表明乔木层的物种丰富度最高,但分布最不均匀,优势种的优势地位突出。 相似文献
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Characterization of the folding degree of proteins 总被引:1,自引:0,他引:1
Estrada E 《Bioinformatics (Oxford, England)》2002,18(5):697-704
MOTIVATION: The characterization of the folding degree of chains is central to the elucidation of structure--function relationships in proteins. Here we present a new index for characterizing the folding degree of a (protein) chain. This index shows a range of features that are desirable for the study of the relation between structure and function in proteins. RESULTS: A novel index characterizing the folding degree of (protein) chains is developed based on the spectral moments of a matrix representing the dihedral angles (phi, omega and epsilon) of the protein main chain. The proposed index is normalized to the chain size, is not correlated to the gyration radius of the backbone chain and is able to distinguish between structures for which the sum of the main-chain dihedral angles is identical. The index is well correlated to the percentages of helix and strand in proteins, shows a linear dependence with temperature changes, and is able to differentiate among protein families. AVAILABILITY: On request from the author. 相似文献
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An index is presented of 375 articles which appeared in Vol. 51–73 of Vegetatio. A Source index is followed by a Keyword index, a Discipline index, a Vegetation type index, a Geographical index, and a Latin name index for taxa and syntaxa. The codes used for discipline, vegetation type and geographic area are the same as those used in the Index Vol. 1–50. After a short introduction a history of the journal is presented, followed by some statistics on the origin of the authors and the type of article, for seven periods covering the entire history of the journal since 1948. Finally the codes are elucidated. 相似文献
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俄罗斯族体质特征分析 总被引:28,自引:4,他引:24
本文报道了内蒙古地区336名俄罗斯族成年人(男186,女150)的体质特征,包括9项形态观察项目,58项测量项目,38项指数及其分型,并与国内外一些群体的体质特征进行了比较。俄罗斯族的主要特征是:绝大多数人具上眼睑褶皱,约1/3的人有蒙古褶。头圆、高、阔,鼻根高,鼻翼中等,鼻狭长,黑发与浅黄肤色较多,眼色的性别差异明显。男性平均身高167.7cm,女性平均身高155.9cm。宽胸型、宽肩型、宽骨盆型、中躯干型、中腿型出现率较高,指距长,体型多属矮胖型,女性更明显。俄罗斯族体质特征与乌孜别克族较接近,其体格健壮程度相对接近俄罗斯北部地区人群。 相似文献
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This paper proposes maneuverability indexes for a control stick that are based on consierations of muscle characteristics.
The indexes are defined on the basis of muscle forces: stiffness of the musculoskeletal system and torque for accelerating
the stick. Measuring muscle forces with electromyography, we examine the effectiveness of the proposed indexes experimentally.
In a slow tracking operation, the index based on stiffness conforms to the subjective evaluation, but the index based on the
torque is inadequate as an index of maneuverability; we therefore use the index based on stiffness as the maneuverability
index. In experiments on a step operation, we divided the operation into two phases: moving and holding. The index in the
holding operation is in good agreement with the subjective evaluation. In both tracking and step operations the characteristics
of the index are appropriate whether or not the controlled object has a first-order lag element. As a result, it is shown
that the index can indicate the maneuverability in the low-frequency tracking operation of the stick.
Received: 5 August 1995 / Accepted in revised form: 25 March 1996 相似文献
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Rasmus Nielsen 《Molecular phylogenetics and evolution》1997,7(3):346-351
If substitutions in DNA sequences follow a Poisson process, the ratio of the variance in the number of substitutions to the mean number of substitutions (the index of dispersion) should equal 1. In this paper, the robustness of the commonly applied estimator of the index of dispersion in replacement sites and silent sites to various assumptions regarding DNA evolution is explored using simulation methods. The estimate of the index of dispersion may be strongly biased if the assumptions of the model of substitution are violated. However, the results of this study support the conclusions of studies by Gillespie and Ohta that the process of substitution in replacement sites is overdispersed. This result contradicts those of a recent study and shows that the high index of dispersion for replacement sites is not an artifact caused by the method of estimation. 相似文献
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植被指数的地形效应研究进展 总被引:2,自引:0,他引:2
植被指数是定性、定量评估绿色植被的关键指标,已经广泛应用于地表植被的监测.森林多分布在地形复杂山区,利用植被指数进行森林植被信息反演时地形对其影响较大.本文从几何光学模型原理分析了冠层反射率的地形效应,分析比较完全比值型植被指数(简单比值植被指数SR、归一化植被指数NDVI和湿度调整植被指数MAVI)、非完全比值型植被指数(增强型植被指数EVI和土壤调整植被指数SAVI)、非比值型植被指数(减化比值植被指数RSR、修正归一化植被指数MNDVI和绿度植被指数GVI),以及地形调节植被指数TAVI对地形的响应,试图为复杂地形山区选取植被指数提供参考.最后分析了植被指数地形效应研究的不足并对未来发展进行展望. 相似文献
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Several groups of investigators are measuring transcapillary protein flux in the lung using noninvasive methods. Results from these studies are reported using several different protein transport indexes, including pulmonary transvascular transfer coefficient, relative extravascular protein, pulmonary transcapillary escape rate, protein leak index, lung transferrin index, slope index, and lung-to-heart count ratios. The purpose of this study is to discover the relationships between these indexes by employing a two-compartment theory of protein transcapillary transport in the lung. We found that all the above indexes can be related to a single index, which we call the normalized slope index. This index is the time rate of change of radioactivity originating from protein in lung interstitium divided by radioactivity arising from protein in lung plasma, normalized by this ratio at time 0, and corrected for blood volume changes. In particular the normalized slope index is shown to be the same as pulmonary transcapillary escape rate under normal sampling conditions and is relatively unaffected by changes in interstitial volume. The response of the normalized slope index to changes in microvascular pressure and microvascular permeability is explored by applying a two-pore model of the microvascular barrier. Results indicate that the normalized slope index is relatively insensitive to changes in microvascular pressure but is greatly affected by changes in microvascular permeability (i.e., changes in large-pore size or number). Since all published leak indexes are related, we would encourage all investigators in the field to adopt a single leak index. We recommend that when a two-compartment model is applied to external detection data, the results be expressed as pulmonary transcapillary escape rate.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
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《农业工程》2022,42(5):467-475
Inspiration is an essential service within cultural ecosystem services. However, there is little research on the inspirational value due to the limitations of the available data. A large number of Chinese poetries mention a variety of ecological elements that inspired poets' creativity. This collection of poetries is the embodiment of the inspirational cultural ecosystem service and provides a new data source for evaluating the inspirational value of cultural ecosystem services. We established the ecological element diversity index and inspirational value index model to evaluate inspirational service. We investigated the poetry from the West Lake in Hangzhou City and the Yunlong Lake in Xuzhou City, China. The results showed the following: (1) The calculation of the ecological elements yielded four levels. The value of the first level was more than four times that of the fourth level. (2) The inspirational value index of plants is the highest in the classification of the ecological elements, followed by meteorological elements, animals, bodies of water, and topography. (3) Among the specific ecological elements, the wood-inspired value index is the highest, 108,855.24, followed by wind and birds, which are 100,665.80 and 89,305.85, respectively, and 71.05% of the value index is between 0 and 10,000. (4) The inspirational value index of the West Lake is 7076.13, and it is 17.08 for the Yunlong Lake. Therefore, the research method of this study provides a new way to evaluate the inspirational value of cultural ecosystem services. 相似文献
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The Harmonic Ratio (HR) is an index based on the spectral analysis of lower trunk accelerations that is commonly used to assess the quality of gait. However, it presents several issues concerning reliability and interpretability. As a consequence, the literature provides very different values albeit corresponding to the same populations. In the present work, an improved harmonic ratio (iHR) was defined, relating the power of the intrinsic harmonics (i.e. associated with the symmetric component of gait) to the total power of the signal for each stride, leading to a normalised index ranging from 0 to 100%. The effect of the considered number of harmonics and strides on the estimate of both HR and iHR was assessed. The gait of three groups of volunteers was investigated: young healthy adults, elderly women and male trans-femoral amputees. Both HR and iHR were able to discriminate gait deviations from the gait of young healthy adults. Moreover, iHR proved to be more robust with respect to the number of considered harmonics and strides, and to exhibit a lower inter-stride variability. Additionally, using a normalised index as iHR led to a more straightforward interpretation and improved comparability. The importance of standardised conditions for the index evaluation was unveiled, and, in order to enhance the future comparability of the index, the following guidelines were presented: considering at least 20 harmonics and 20 strides; expressing the acceleration components in a repeatable, anatomical, local system of reference; and evaluating the iHR index, rather than the traditional HR. 相似文献
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月亮山景区景观格局分析研究 总被引:5,自引:0,他引:5
根据景观生态学原理,区域的景观空间格局与生态过程具有较大关系。运用GIS技术,选取了景观多样性指数(H)、优势度(D)、均匀度(E)、景观破碎度(C)、景观分离度(I)五个景观指数,分析了"三江并流"国家级风景名胜区月亮山景区规划前后的格局变化。结果表明:规划后,景区内增加了风景游赏用地、游赏设施用地、交通设施用地、滞留用地等四种新的土地利用类型,形成了新的景观格局。景观层面:整体优势度下降、多样性上升、均匀度上升;斑块层面:林地、灌木林、荒草地和水域的破碎度上升,耕地的破碎度下降。林地的分离度上升,灌木林、荒草地的分离度下降。总的来说,规划对生态环境的影响不明显,且增加了景区趣味性,有利于生态保护及旅游活动的开展。 相似文献
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小菜蛾颗粒体病毒对小菜蛾防治作用的评价 总被引:6,自引:1,他引:5
用以作用因子组配的生命表,种群趋势指数和控制指数评价小菜蛾颗粒体病毒对小菜蛾种群动态的作用。结果表明,施用该病毒对小菜蛾种群动态有明显的控制作用,种群趋势指数为0.97,干扰作用控制指数为0.19,即施用病毒后,其种群趋势指数相当于对照的0.19,施用化学杀虫剂的种群趋势指数为7.20,干扰作用控制指数为1.43,即种群趋势指数将增长为对照的1.43倍。 相似文献
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Numerous studies have linked individual nutrient loadings from the Mississippi and Atchafalaya Rivers to the growth of the hypoxic, or oxygen depleted, zone in the northern Gulf of Mexico. However, in the discussion of policy to remediate Gulf hypoxia, it is beneficial for stakeholders and policymakers to obtain a single measure for water quality that characterizes information from multiple water pollutants. This study aggregates loadings from six nutrients measured at the entrance to the Gulf of Mexico into a single time-varying index of water quality. The index is constructed using traditional index number theory originating from economic production theory, mainly, Shephard’s distance functions calculated using data envelopment analysis (DEA). The methodology is an advance over other index construction schemes because the determined metric weights are endogenous, calculated from the data itself, and do not require external user input. To validate the index, May values of the index are used within a statistical regression model to model the areal extent of Gulf hypoxia using mid-July cruise measurements from 1985 to 2013, excluding 1989 when no cruise data were available. Regression results (R2adj = 0.81) suggest the index is successful at aggregating multiple pollutants into a single measure of water quality and may be useful for tracking their aggregated effect on the growth of the hypoxia area in the northern Gulf of Mexico. Calculation of the water quality index described here is automatic in the sense that no human intervention is required for variable selection, statistical analysis or assignment of weights. This is very useful for specifying a water quality objective in a multiple objective optimization for watershed management. 相似文献
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三峡水库运行后洞庭湖洲滩 小型兽类群落状况 总被引:1,自引:0,他引:1
为了探究三峡工程建成运行后洞庭湖区洲滩生境中小型兽类的群落状况,对洞庭湖区洲滩生境的小型兽类进行调查。调查采用铗日法,于2010至2018年,对洞庭湖区洲滩小型兽类群落的多样性进行了调查,并计算优势度、群落多样性指数、均匀性指数。对多样性指数采用t值法进行比较,各年份、生境的捕获率及鼠种组成差异则采用卡方检验。2010至2018年,共布放34 116铗日,捕获可以分辨种类的样本2 129只,主要有啮齿目(Rodentia)和鼩形目(Soricomorpha)2类,共7种,分别是啮齿目的东方田鼠(Microtus fortis)、黑线姬鼠(Apodemus agrarius)、褐家鼠(Rattus norvegicus)、巢鼠(Micromys minutes)、社鼠(Niviventer confucianus)、黄毛鼠(R. losea)和鼩形目的臭鼩(Suncus murinus)。总捕获率为6.36%,东方田鼠、黑线姬鼠捕获率较高,分别为1.83%、3.94%。从小型兽类组成看,黑线姬鼠和东方田鼠在群落中组成的比例较高,分别为63.18%和29.26%。在调查的5类生境中,植被组成以苔草(Carex sp.)、南荻(Miscanthus sp.)和美洲黑杨(Populus deltoides)为主的生境小型兽类群落多样性指数(1.0772)和均匀度指数(0.6662)均最大,其次是以苔草为主的生境(多样性指数和均匀度指数分别为0.9275、0.5723)、以南荻为主的生境(多样性指数和均匀度指数分别为0.8856、0.550 2)和以苔草加南荻为主的生境(多样性指数和均匀度指数分别为0.775 6、0.481 9),以美洲黑杨为主的生境多样性指数(0.323 6)和均匀度指数(0.180 6)最低,但其优势度最高,为0.881 2。结果表明,随着三峡工程的运行,洞庭湖区植被演替发生了变化,从而引起小型兽类群落动态的变化。在洞庭湖洲滩上,生境越复杂,小型兽类物种多样性越高。单一生境下,人类活动干扰程度越大,小型兽类物种多样性越低。目前,黑线姬鼠已经成为洞庭湖洲滩生境的第一优势鼠种。 相似文献
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塔里木河下游植物群落的物种数量变化与生态系统动态研究 总被引:13,自引:1,他引:13
物种多样性是指物种及其集合体的生物学多样性。物种多样性研究的核心是物种的数量变化和物种的生物学多样性程度。本文根据野外采集的数据 ,运用Simpson指数、McIn tosh指数以及Margalef指数 ,对塔里木河下游英苏、阿布达勒、喀尔达依、阿拉干、依干不及麻等地区的物种多样性指数分别进行了计算 ,并根据计算得到的生物多样性指数探讨了干旱区退化生态系统的物种多样性以及在干旱区物种多样性与生态系统稳定性之间的关系。结果表明 ,塔里木河下游从英苏至依干不及麻 ,Simpson多样性指数的变化范围为 0 82~ 0 2 6 ,McIn tosh均匀度指数的变化范围为 0 6 0~ 0 1 8,Margalef丰富度指数的变化范围为 1 4 7~ 0 38,物种数的变化范围是 9~ 2。分析表明塔里木河下游生态系统退化十分严重 ,并据此讨论了塔里木河下游生态系统退化的特征、演替动态及稳定性 相似文献
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孟家岗林场森林景观结构动态分析 总被引:2,自引:0,他引:2
以黑龙江省孟家岗林场1989年和2006年两期森林资源二类调查数据为基础,结合林相图,利用GIS技术和景观格局分析软件包FRAGSTATS进行分析,提取森林景观要素内部结构指标等景观指数,并对孟家岗林场近20年的景观格局的动态特征进行了系统的分析。研究结果表明:由于孟家岗林场森林景观要素类型的增加以及多样性和优势度指数的增高,使得森林景观的分离度和破碎度也在增加;虽然落叶松林为该研究区域的优势景观要素类型,但其优势度却在逐渐降低,表明落叶松景观要素在向其它景观要素类型转化;首次对孟家岗林场进行景观内部结构指数分析,表明阔叶树和混交林景观要素类型是以成、过熟林为主,三大主要针叶树种以中龄林和近熟林为主。人为干扰的加剧,使针叶林年龄结构趋于单一化。 相似文献
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From 31 children with acute lymphoblastic leukaemia the mitosis index in the bone-marrow was determined before the onset of therapy and during the clinical progress. Initially, the mean white mitosis index lay with 3.4% below that of the normal test persons, it rose significantly in the hematologic full remission and showed a decreasing tendency with a great range of dispersion in the recidive. The most lowered mitosis index was found in the final stage. Strong shifts in the kariologic distributions make a remaining in the prophase of the mitosis evident. The influence of polychemotherapy on the mitosis index and the phases of mitosis is discussed. Correlations between the mitosis index and clinical as well as paraclinical parameters were only to be found with respect to granulocytes and lymphoblasts. The considerable ranges of fluctuations of the mitosis index and the lack of congruity with the clinical progress of ALL allow no ensured assertions to be made for the single patient. It seems to be important in eosinophilia and in leukaemoid reactions. 相似文献