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Lahav O Naim A Buta RJ Corwin HG de Vaucouleurs G Dressler A Huchra JP van den Bergh S Raychaudhury S Sodré L Storrie-Lombardi MC 《Science (New York, N.Y.)》1995,267(5199):859-862
The quantitative morphological classification of galaxies is important for understanding the origin of type frequency and correlations with environment. However, galaxy morphological classification is still mainly done visually by dedicated individuals, in the spirit of Hubble's original scheme and its modifications. The rapid increase in data on galaxy images at low and high redshift calls for a re-examination of the classification schemes and for automatic methods. Here are shown results from a systematic comparison of the dispersion among human experts classifying a uniformly selected sample of more than 800 digitized galaxy images. These galaxy images were then classified by six of the authors independently. The human classifications are compared with each other and with an automatic classification by an artificial neural network, which replicates the classification by a human expert to the same degree of agreement as that between two human experts. 相似文献
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运用对比分析法、文献研究法等,阐释开发区土地利用分类的形式、内容及与其他分类的区别,探讨开发区土地利用分类的实用性。结果表明:开发区土地按照土地建设状况和供应状况划分为2类,统一编码排列;分类反映了不同的土地基本特性和本质差异,体现了由大到小、由一般到特殊、由高级到低级的等级层次,存在明显的从属和逻辑关系,且2种分类之间存在明显的并列关系;开发区土地利用分类与其他土地利用分类系统在分类目的、适用对象、分类标准、层次设定等方面都有所不同,且应在土地分类中以科学方式增加一些新兴产业地类的分类。 相似文献
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灰色聚类法在湿地水体富营养化评价中的应用 总被引：14，自引：0，他引：14
将灰色聚类法应用到湿地水体富营养化评价中，旨在建立起一套比较完善、适合于湿地水体富营养化的评价体系。把湿地水体富营养化程度划分为6个级别，其阚值参照中国湖泊富营养化评价标准和湿地富营养化的特点。利用灰类白化权函数描述水体富营养化分级界限，正确地选择了各参评指标对于各等级的聚类权，在此基础上构建了湿地水体富营养化灰色聚类法综合评判模型。并以扎龙湿地为例进行了实例计算与分析，验证了此模型的准确性、可比性和实用性。 相似文献
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分类法在网络环境下的应用现状分析 总被引：4，自引：0，他引：4
文章以《杜威十进分类法》(DDC)、《中图法》等中外著名传统分类法为例,对传统分类法在网络环境下的应用现状以及中文浏览型网站中的分类系统、英文分类目录型网站中的分类体系进行了分析和对比,进而说明在网络环境下分类法如何充分发挥在组织网络信息资源上具有的潜力,从而保持其旺盛的生命力。 相似文献
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应用木材解剖学对长白松、樟子松、赤松木材进行了全面解剖研究。发现三种木材的射线管胞内壁具有深锯齿,其平均高度达5.70μm,交叉场纹孔均为窗格状和松型;筛选出彼此不同的15个解剖特征采用数量分类学系统分类法进行运算,得出长白松同樟子松相近即与欧洲赤松(paals syvestris linn)相近,故确认其当归属于欧洲赤松种群范畴。 相似文献
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水生无脊椎动物血淋巴细胞分类及免疫研究进展 总被引：3，自引：0，他引：3
水生无脊椎动物的血淋巴细胞是机体免疫防御屏障的重要组成部分,但对不同水生无脊椎动物的血淋巴细胞分类和功能的研究整体上比对脊椎动物的研究落后。本研究中系统地归纳和综述了贝类、甲壳类、棘皮动物等水生无脊椎动物血淋巴细胞的分类及其免疫功能的研究进展,贝类血淋巴细胞的分类主要以染色后细胞质中颗粒物质的有无作为指标,一般分为颗粒细胞(granulocyte)和透明细胞(hyalinocyte),其防御机制主要通过包囊作用、伤口修复、吞噬作用等方面体现;甲壳动物血淋巴细胞的分类主要依据血淋巴细胞的形态特征和胞质中颗粒物质的有无、大小和密度等特征,一般将其分为无颗粒细胞(hyaline cell)、小颗粒细胞(semi-granular cell)和大颗粒细胞(granular cell),透明细胞和小颗粒细胞共同介导吞噬作用,小颗粒细胞还介导包囊作用,大颗粒细胞主要介导细胞毒作用;棘皮动物的细胞免疫主要由体腔细胞即变形吞噬细胞或颗粒细胞完成。建议未来应使用多种方法和技术以及结合血淋巴细胞表面受体对水生无脊椎动物血淋巴细胞进行分类和功能研究。 相似文献
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为了提高陆地卫星TM数据在山区林地的分类精度,利用4个季节的帽儿山TM数据进行植被分类,并辅助以物候特征和地面GIS专题信息 采用由简单到复杂的信息提取过程,先利用基于光谱知识的林地提取模型提取林地边界,再用有监分类方法分别进行林地和非林地内部类型信息的提取,生成多季相综合分类图 分类精度比单时相提高了19 6% 相似文献
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植物自交不亲和反应(self-incompatibility,SI)是开花植物防止自交退化,保持遗传多样性的一种常见的生殖隔离现象。自交不亲和的机制具有多样性及独立性,各个科之间的自交不亲和机制起源不同而且不亲和基因之间也不存在同源性。归纳总结了植物自交不亲和的几种分类情况,并按其分类对不同种类的自交不亲和机制分别进行了阐述。在此基础上,对植物自交不亲和领域研究的难点和方向进行了分析和展望。 相似文献
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Mayr E 《Science (New York, N.Y.)》1981,214(4520):510-516
Currently a controversy is raging as to which of three competing methodologies of biological classification is the best: phenetics, cladistics, or evolutionary classification. The merits and seeming deficiencies of the three approaches are analyzed. Since classifying is a multiple-step procedure, it is suggested that the best components of the three methods be used at each step. By such a synthetic approach, classifications can be constructed that are equally suited as the basis of generalizations and as an index to information storage and retrieval systems. 相似文献
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Many farmers want to take advantage of modern technology to control fertilizer applications in large fields more precisely in smaller zones. We have investigated zonation on past yields by three forms of k-means clustering with geostatistical smoothing and compared the outcomes with yield response to added nitrogen. We had data on wheat yield for three years on 2187 10 × 10 m squares in a 29-ha field in the English midlands. Two of the methods grouped the squares by a ‘hard’ means technique, the first used their similarities which had been modified with their spatial covariance function and the second used their dissimilarities which had been modified with their variogram. The third method computed their memberships to fuzzy classes and smoothed the memberships with the variogram for final classification. The resulting spatially smoothed classifications were evaluated by the extent to which they responded differentially to applied nitrogen in a fourth year.The best compromise between spatial coherence and minimum variance seemed to be the smoothed fuzzy classification; it created reasonably compact zones that a well-equipped farmer might be able to manage. However, the nitrogen response functions were parallel, and it is unlikely that a farmer would benefit financially by fertilizing the zones separately. The soil map of the field also distinguished coherent compact zones, and these differed in the forms of the responses of their crops to fertilizer nitrogen. For this field, it might be more profitable to manage the nitrogen application according to soil type. 相似文献
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以赣十I,l市为例,先采用人均建设用地标准法和户均建设用地标准法测算其2020年的农村建设用地整理理论潜力,然后利用层次分析法并构建综合修正模型测算修正后赣州市2020的现实潜力,最后采用多因素综合评价法对全市18个县级行政区的整理潜力进行潜力分级。最终测算得出赣州市2020年农村建设用地整理现实潜力为15878．14hm2全市共划分为4个潜力等级。 相似文献
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土壤分类研究回顾与中国土壤分类系统的修编 总被引：6，自引：0，他引：6
中国在第二次土壤普查（二普）中,由百余名土壤科学家共同制定了中国土壤分类系统,作为二普用规范性文档,二普后作为国标在全国推荐使用。对二普分县调查资料的首次汇总显示,从分县资料提取出的土壤分类名与国家标准发布的分类名存在一定差异。为对与国标不符的土壤类型名进行审核和修编,同时弄清中国现有两套土壤分类系统之间,以及这两套系统与世界土壤资源参比基础（WRB）之间的关联,对土壤分类研究进展及存在问题进行了回顾与分析。本研究显示,土壤发生学是各国进行土壤分类的共同基础,虽然理论基础相同,由于不同国家和地区所处气候带不同,拥有的土壤资源类型和人均资源量不同,经济与科技发展水平不同,采用的分类原则、命名规则、地面调查方法和采样量各有差异,最终形成的分类系统各不相同。受各国语言习惯和已有分类系统影响,也受近年来在土壤调查中对了解成土过程需求在弱化的影响,对各国土壤分类系统的整合进展并不顺利。对不同语言土壤分类系统的比较显示：中国国标分类系统更符合汉语语言特征,特别是高层级分类中的60个土类命名,能较好表达中国主要土壤类型的典型特征,易于专业及非专业人员对土壤类型及成土过程的认知,且推广应用时间已有30多年,在全国影响较大,应继续采用。国标分类系统不便进行国际交流的问题应通过建立其高层级分类,特别是国标中60个土类与世界参比基础的关联加以解决。研究表明,将土壤分类名限定于对成土过程的描述,有利于分类系统的稳定和对主要土壤类型成土过程的认知,在层级结构上对分类系统的不断调整,或将成土过程以外的土壤质量评价引入分类系统,将导致繁冗的土壤分类名,弱化对成土过程认知。由于土壤发生分类信息是进行土壤功能性状调查、评价和分类的重要辅助信息,将土壤分类限定于描述发生分类还有利于将其用于阐明土壤肥力、土壤环境和土壤健康功能性状。根据上述观点,对分县资料中土壤类型名进行了编审,土类按照国标发布的60个土类进行了归并,亚类进行了适度归并,在土属和土种名编审中,则对名称中源于现场调查的土壤分类信息尽量予以保留。 相似文献
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生态系统服务分类的研究进展 总被引：1，自引：0，他引：1
建立一套科学有效的生态系统服务分类体系不仅是生态系统服务研究的重点内容,也是全面客观地评估生态系统服务价值的重要前提。通过回顾生态系统服务及其分类体系的发展过程,对生态系统服务分类体系的研究现状进行了综合评述,探讨分析了现有分类体系中存在的问题及未来发展趋势。最后指出,只有不断提高对生态系统的认识,考虑人类福利与需求,结合决策背景与目的,才能得到合理的分类体系,进而精确评价生态系统服务。 相似文献
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In general, the analysis of hyperspectral remote sensing data by means of pattern recognition and/or classification is known to be data dependent. Thus, conventional methods for classifications may not be applicable due to the large amount of data collection used to characterize hyperspectral data in terms of optimality and computational time. In this paper, efficient classification methods of hyperspectral data are presented. Hyperspectral signatures are then extracted for eight different sample types (bare soil, soybean, mixed weeds, combination of soybean and weeds, sicklepod, entireleaf morning glory, pitted morning glory, and common cocklebur) and used for observing their spectral properties for detection and/or classification. The hyperspectral data that are analyzed in this paper are point source data collected from handheld spectrometers. The resulting data classification is reported accordingly and a comparative study among the various methods is made to ascertain their applicability to discriminate between the various sample types. 相似文献
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Ciccarelli FD Doerks T von Mering C Creevey CJ Snel B Bork P 《Science (New York, N.Y.)》2006,311(5765):1283-1287
We have developed an automatable procedure for reconstructing the tree of life with branch lengths comparable across all three domains. The tree has its basis in a concatenation of 31 orthologs occurring in 191 species with sequenced genomes. It revealed interdomain discrepancies in taxonomic classification. Systematic detection and subsequent exclusion of products of horizontal gene transfer increased phylogenetic resolution, allowing us to confirm accepted relationships and resolve disputed and preliminary classifications. For example, we place the phylum Acidobacteria as a sister group of delta-Proteobacteria, support a Gram-positive origin of Bacteria, and suggest a thermophilic last universal common ancestor. 相似文献