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1.
图聚类用于蛋白质分类问题可以获得较好结果,其前提是将蛋白质之间复杂的相互关系转化为适当的相似性网络作为图聚类分类的输入数据。本文提出一种基于BLAST检索的相似性网络构建方法,从目标蛋白质序列出发,通过若干轮次的BLAST检索逐步从数据库中提取与目标蛋白质直接或间接相关的序列,构成关联集。关联集中序列之间的相似性关系即相似性网络,可作为图聚类算法的分类依据。对Pfam数据库中依直接相似关系难以正确分类的蛋白质的计算表明,按本文方法构建的相似性网络取得了比较满意的结果。  相似文献   

2.
中国昆虫区系的多元相似性聚类分析和地理区划   总被引:3,自引:0,他引:3  
为了总结分析中国昆虫的分布规律, 为昆虫地理区划提出依据, 作者2008年创建了新的多元相似性聚类分析方法, 它与传统的聚类分析方法的主要不同是直接计算任意多个地区之间的相似性系数, 从而摈弃原来的合并环节。我们应用这种方法对中国823科17 018属93 662种昆虫的分布进行了定量分析。当种级水平相似性系数分别为0.19和0.14时, 全国64个基础地理单元聚类为20个小单元群和9个大单元群。根据聚类分析结果, 提出我国第一个由定量分析产生的9个昆虫区20个昆虫亚区的中国昆虫地理区划的初步方案。西北昆虫区、 东北昆虫区、 华北昆虫区、 青藏昆虫区稳定地组成中国北方昆虫大区, 江淮昆虫区、 华中昆虫区、 西南昆虫区、 华东昆虫区、 华南昆虫区稳定地组成中国南方昆虫大区。江淮昆虫区的设立是因为这里多平原和丘陵, 为重要农业区, 昆虫区系简单, 种类显著少于华东、 华中、 华南昆虫区, 而和华北昆虫区相当; 包括台湾在内的华东昆虫区是昆虫多样性最丰富地区之一, 显著高于邻近的华北、 江淮、 华南昆虫区。最后, 对昆虫地理定量分析中的重要环节进行讨论, 还对今后昆虫区系调查的薄弱地区提出建议。这项研究证明多元相似性聚类分析方法是简便、 快捷、 实用的, 能够在更广泛的范围应用, 这预示着生物地理学研究将会由定性研究进入到定量研究阶段。  相似文献   

3.
目的:探讨A和B两神教学方法在护理专业人体形态学教学中的应用及比较.方法:通过应用A和B两种教学法,对全日制护理学专科2010-2班和护理学专科2011-2班的人体形态学期末考试平均成绩和及格率进行比较和分析.结果:采用A教学法的护理学专科2011-2班的最高分为88分,最低分为42,平均成绩为75.45分,标准差为10.34.采用B教学法的护理学专科2010-2班的最高分为84分,最低分为36,平均成绩为64.34分,标准差为11.65.对护理学专科2011-2班和2010-2班的平均成绩进行F检验,F=1.12<1.50,故P>0.10,方差齐,敌可用方差相等情形的两样本t检验,t=5.36>2.66,故P<0.01,两组平均成绩之间差异有统计学意义;采用A教学法的护理学专科2011-2班的及格率为81.54%,采用B教学法的护理学专科2010-2班的及格率为65.15%.对于以上两个班及格率进行卡方检验,x=4.49>3.84,故P<0.05,两组及格率之间差异有统计学意义.以上结果说明采用A教学法的护理学专科2011-2班的平均成绩和及格率明显高于采用B教学法的护理学专科2010-2班.结论:在人体形态学教学中,A教学法跟B教学法比具有明显的优势,同时A教学法自身也有不足之处.  相似文献   

4.
陈昭 《人类学学报》2013,32(3):264-273
随着人体组成学中文版的发行和人体组成测量培训班在中国的举行, 中国生物人类学家对人体组成测量方法在科研中的运用有了更大的兴趣。该文对人类学家,如Jindr?ich Matiegka和Stanley MarionGarn在人体组成学发展中的历史贡献做了基本的介绍。此外, 作者还以Garn博士的工作为例, 去激励中国生物人类学家开展人体组成学的研究工作。文章讨论了人体组成成分的测量方法在生物人类学中的用途, 并介绍了人体组成学的基本理论和概念及近年来人体组成学的变化: 如影像技术的发展, 影像技术作为"金标准"对评估其他人体组成测量方法的用途, 双能量x线吸收法的优势, 生物电阻分析法的广泛运用, 和多种人体组成测量方法相辅相成的现象。作者对常用的人体组成测量方法的优缺点做了比较, 并指出人体组成成分测量是人体测量方法的自然延续, 人体组成学和生物人类学的关系渊源已久; 因此中国人类学家应当更多地利用人体组成测量方法对人体差异做更深入的研究, 并注重人体差异同健康疾病和生物医学的关系, 以便让生物人类学更好地为当今社会服务。  相似文献   

5.
更新教学理念,构建人体形态学实验教学新体系   总被引:1,自引:0,他引:1  
怀化医学高等专科学校医学形态学实验学中心,以现代教育教学理念为指导,以"三基"训练为基础,以综合素质培养为核心,以创新能力提高为主线.以适应社会能力为目标来重点培养学生的探索精神、科学思维、实践能力、创新能力,构建了"统一规划、三个层次、分类实施、开放教学"的医学形态学实验教学体系.  相似文献   

6.
郭依泉  赵志模 《生态学杂志》1992,11(3):65-68,71
群落是指一定地段或生境里各种生物种群构成的结构单元。群落内各物种不是孤立存在的,它们之间存在着极为复杂的营养联系。一种植物常有多种害虫取食,一种害虫可取食多种植物,同时又被多种天敌捕食或寄  相似文献   

7.
张继宗 《人类学学报》1991,10(3):231-237
本文对106名中国东北汉族女性进行了活体测量,并拓取了掌指纹。样本的年龄范围为18—34岁。所分析的人体测量指标共41项,掌指纹指标共59项。将人体测量指标与掌指纹指标同时输入电子计算机,进行了100项实验指标间的相关分析,并做了相关显著性检验。在41项人体测量指标中,有35项指标与掌指纹特征有相关关系。其中与掌指纹特征同时相关的人体测量特征有18项,与指纹特征相关的人体测量指标有2项,与掌纹相关的人体测量指标有15项。与掌指纹特征同时相关的人体测量特征,与遗传因素之间的相互关系大于与指纹相关的人体测量特征。与指纹相关的人体测量特征,与遗传因素的关系,要大于与掌纹相关的人体测量特征。  相似文献   

8.
目的 根据中医人体形态学科特点构建以生命观为核心,结合中西医解剖学史为两翼的1+2+N的课程思政模式,线上线下与专业课程教学有机结合.方法 比较了相同教学背景下连续3年学生的形成性成绩和期末成绩,在线调查医学生对课程思政的满意度.结果 通过课程思政,学生形成性成绩和期末成绩总体都有提高,调查统计显示绝大多数医学生赞成课...  相似文献   

9.
不同地点蒙古栎群落相似性的研究   总被引:3,自引:0,他引:3  
通过13个地点蒙古栎群落物种相似性与两地之间距离的回归比较,发现蒙古栎群落物种相似性的大小一般决定于不同地点之间的地理位置,两地之间距离越近,其相似性越高,反之则越低,但是群落不同的演替阶段也影响群落的相似性。通过分析蒙古栎群落物种组成的差异及物种相似性系数的比较,蒙古栎群落可分为大兴安岭蒙古栎群落、长白山蒙古栎群落、辽西蒙古栎群落和辽冀蒙古栎群落等几种类型。  相似文献   

10.
疾病相似性研究对于复杂疾病发病机制的理解、诊断、预测和药物研发具有重要意义.最近,研究人员通过集成多种疾病术语库,构建了描述疾病关系的疾病本体(disease ontology,DO),这为从DO角度研究疾病相似性打下了基础.本文综述了基于DO及其注释信息的疾病相似性计算方法,探讨了疾病相似性计算存在的问题和挑战,为疾病相似性进一步的研究提供有益参考.  相似文献   

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Abstract

Conformational switching in the secondary structure of RNAs has recently attracted considerable attention, fostered by the discovery of ‘riboswitches’ in living organisms. These are genetic control elements that were found in bacteria and offer a unique regulation mechanism based on switching between two highly stable states, separated by an energy barrier between them. In riboswitches, the energy barrier is crossed by direct metabolite binding, which facilitates regulation by allosteric means. However, other event triggers can cause switching to occur, such as single-point mutations and slight variations in temperature. Examples of switches with these event triggers have already been reported experimentally in the past. Here, the goal is to computationally design small RNA switches that rely on these triggers. Towards this end, our computer simulations utilize a variety of different similarity measures to assess the distances between an initial state and triggered states, based on the topology of the secondary structure itself. We describe these combined similarity measures that rely on both coarse-grained and fine-grained graph representations of the RNA secondary structure. As a result of our simulations, we provide some candidate sequences of approximately 30–50 nt, along with the exact triggers that drive the switching. The event triggers under consideration can be modelled by Zuker's mfold or the Vienna package. The proposed methodology that rely on shape measures can further be used to computationally generate more candidates by simulating various event triggers and calculating their effect on the shape.  相似文献   

14.
磨盘山遗址是分布在云南省楚雄彝族自治州元谋盆地的一处新石器时代聚落。本文通过对遗址出土的6例新石器时代人骨的体质人类学研究,得出以下结论:磨盘山组颅骨的形态特征可以概括为中颅型与正颅型相结合,阔额型、阔上面型、阔鼻型、中眶型并伴有颇大的面部扁平度;磨盘山组应属于亚洲蒙古人种范畴,在次级分类比较中与南亚类型在鼻眶形态和上面部形态上表现出更多的相似性;在与亚洲蒙古人种各近代组的比较中,磨盘山组与广西壮族组关系最为密切,与蒙古组关系最为疏远;在与其他新石器对比组的比较中,磨盘山组与代表"古华南类型"的甑皮岩组、鲤鱼墩组和昙石山组表现出更多的一致性,与"古中原类型"和"古华北类型"关系疏远。  相似文献   

15.
The eight diagnostic morphological traits of the Sundadont and Sinodont divisions of the Mongoloid dental complex are identified. Intra- and intergroup variation for these crown and root features is plotted. The univariate frequency distributions provide useful evidence for several suggestions about East Asian prehistory, dental microevolution, and intergroup relationships. The case for local evolution of Sundadonty is strengthened by finding Australian teeth to be very similar to this pattern. Australian Aboriginal teeth are also generally like those of Jomonese and some Ainus, suggesting that members of the late Pleistocene Sundaland population could have initially colonized Sahulland as well as the continental shelf of East Asia northward to Hokkaido.  相似文献   

16.
Morphology and the classification of the so-called Cladocera   总被引:7,自引:7,他引:0  
The validity as a monophyletic taxon of the group of branchiopod crustaceans long regarded as constituting the Cladocera is questioned. This seems in fact to be a heterogeneous assemblage whose members probably merit assignment to four separate orders. The Onychopoda and Haplopoda (the so-called Gymnomera) clearly stand apart from the Ctenopoda and Anomopoda (the so-called Calyptomera) and differ in important respects from each other. While sharing several characters, some doubtless indicative of distant ancestral similarities, others probably convergent, the Ctenopoda and Anomopoda differ in many respects, have clearly evolved along different lines, and are probably much less closely related than is generally assumed.  相似文献   

17.
This paper is focused on quantification (morphometry) and modeling of neuronal morphological complexity. First, computer-aided methods for reconstruction, processing, and analysis of raw morphological data are reviewed. Then, topological and metrical measures are touched upon. Fractal measures (together with the extension of multiscale fractal dimension) are presented more explicitly. Models of neuronal arborizations are differentiated between reconstruction models and growth models (stochastic or mechanistic). The growth model approach is discussed in more detail. The methods presented are applied to several types of neurons and shown to have considerable discriminative power. Recent developments stress the importance of these methods for optimizing virtual neuronal trees in view of functional characteristics of the neurons. Neirofiziologiya/Neurophysiology, Vol. 40, No. 4, pp. 366–372, July–August, 2008.  相似文献   

18.
A dog’s craniofacial diversity is the result of continual human intervention in natural selection, a process that began tens of thousands of years ago. To date, we know little of the genetic underpinnings and developmental mechanisms that make dog skulls so morphologically plastic. In this Perspectives, we discuss the origins of dog skull shapes in terms of history and biology and highlight recent advances in understanding the genetics of canine skull shapes. Of particular interest are those molecular genetic changes that are associated with the development of distinct breeds.  相似文献   

19.
Repeated gesturing on touchscreen computing devices has become part of professional, personal, or school use by persons of all ages. Few studies have compared kinematics among joint motions and gestures during touchscreen interaction. We aimed to quantify the relative contributions of the shoulder, elbow and wrist to completion of several gestures to aid understanding of touchscreen ergonomics. Joint angles of the shoulder, elbow, and wrist were recorded for 22 seated participants while they interacted with a 10.1″ tablet computer held on an easel. Joint excursions at the shoulder, elbow, and wrist were all on average ≤20° during touchscreen interaction. The greatest excursion measured was shoulder rotation for swipe right with a mean of 15.5(±6.0)°. Index finger tap on a touchscreen was completed by participants with less than 5° of mean joint excursion at the shoulder, elbow and wrist. Tap, pinch and stretch gestures demonstrated significantly more wrist flexion/extension (p < 0.05) than shoulder flexion/extension, ab/adduction and rotation. Also, swipe left, right and up involved more shoulder rotation (p < 0.05) than wrist flexion/extension. These results suggest that when gestures are repeated frequently, the relative risk of overuse injury at the shoulder, elbow, or wrist may depend on the gesture being repeated.  相似文献   

20.
研究龟鳖的两性异形对理解形态适应具有重要意义。通过测量41只(21♀,20♂)成体四眼斑水龟(Sacalia quadriocellata)的20个形态特征指标,研究四眼斑水龟个体大小和体形的两性异形。结果表明:除头长、头宽、尾长和尾长肛前段长外,四眼斑水龟其他的形态特征均与背甲长呈正相关。雌性的背甲长、腹甲长、腹甲中线长、腹甲曲线长显著大于雄性;雄性的头长、头宽、后肢长、尾长和尾长肛前段长显著大于雌性;雌雄两性的体重、体周长、前肢长、腹甲宽、肛盾切口长、肛盾切口宽以及除背甲长外的所有背甲形态特征指标均无显著差异。研究结果表明,四眼斑水龟存在个体大小和体形两性异形。  相似文献   

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