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1.
粗糙集神经网络在昆虫总科阶元分类学上的应用 总被引：2，自引：0，他引：2
为研究粗糙集和神经网络相结合方法的实践性,以及昆虫的数学形态特征在总科阶元上作为分类特征的可行性、可靠性和重要性。从总科角度对鳞翅目(Lepidoptera)和鞘翅目(Coleoptera)5个总科23种虫体图像中提取的昆虫面积、周长等11项数学形态特征进行粗糙集神经网络分析。结果表明:在总科阶元上,11项特征的可靠性大小为,面积、亮斑数>周长、横轴长、形状参数、圆形性、似圆度、偏心率>纵轴长、叶状性、球状性,与赵汗青等的统计分析结果中属性特征的重要性大多数一致;神经网络模式识别结果与传统分类结果完全一致。应用粗糙集理论进行昆虫数学形态特征分类结果准确;在昆虫总科阶元分类上粗糙集神经网络较统计学方法具有优势。 相似文献
2.
利用翅的数学形态特征对蛾类昆虫进行分类鉴定的系统研究Ⅰ——在总科级阶元上的应用 总被引：1，自引：1，他引：0
以农林业主要蛾类害虫为研究对象,应用其翅的数学形态特征在总科阶元上进行分类鉴定。对鳞翅目5总科40种蛾类的右前翅和右后翅的偏心率、球状性、叶状性、似圆度、矩形度、延长度以及不变矩Hu1、Hu2等共计26项与大小和方向均无关的数学形态特征,利用方差分析、逐步判别分析和聚类分析等方法论证各项数学形态特征在总科阶元上进行分类的可行性、可靠性和重要性,并且从数学形态学角度对同阶元昆虫类群的亲缘关系做了描述。结果表明:在总科阶元上可筛选出6个形态特征作为分类变量,它们的作用大小依次为:(FW矩形度、FWHu5、HW偏心率)>HW似圆度>(HW矩形度、HWHu5),回归判别和交叉判别的结果其正确率分别为100%和97.5%。 相似文献
3.
Network motifs: simple building blocks of complex networks 总被引：4，自引：0，他引：4
Milo R Shen-Orr S Itzkovitz S Kashtan N Chklovskii D Alon U 《Science (New York, N.Y.)》2002,298(5594):824-827
Complex networks are studied across many fields of science. To uncover their structural design principles, we defined "network motifs," patterns of interconnections occurring in complex networks at numbers that are significantly higher than those in randomized networks. We found such motifs in networks from biochemistry, neurobiology, ecology, and engineering. The motifs shared by ecological food webs were distinct from the motifs shared by the genetic networks of Escherichia coli and Saccharomyces cerevisiae or from those found in the World Wide Web. Similar motifs were found in networks that perform information processing, even though they describe elements as different as biomolecules within a cell and synaptic connections between neurons in Caenorhabditis elegans. Motifs may thus define universal classes of networks. This approach may uncover the basic building blocks of most networks. 相似文献
4.
Development of the animal body plan is controlled by large gene regulatory networks (GRNs), and hence evolution of body plans must depend upon change in the architecture of developmental GRNs. However, these networks are composed of diverse components that evolve at different rates and in different ways. Because of the hierarchical organization of developmental GRNs, some kinds of change affect terminal properties of the body plan such as occur in speciation, whereas others affect major aspects of body plan morphology. A notable feature of the paleontological record of animal evolution is the establishment by the Early "Cambrian of virtually all phylum-level body plans. We identify a class of GRN component, the kernels" of the network, which, because of their developmental role and their particular internal structure, are most impervious to change. Conservation of phyletic body plans may have been due to the retention since pre-Cambrian time of GRN kernels, which underlie development of major body parts. 相似文献
5.
zpyue@yahoo.com.cn。 《勤云标准版测试》2006,(3)
选择素是一种非免疫来源的多价糖类结合蛋白,为细胞粘附分子(celladhesionmolecules,cAMs)超家族的一员,选择素家族有3个结构类似的成员:E-选择素、L-选择素、P-选择素,它们在炎症发生时可介导白细胞与血管内皮细胞之间、白细胞与白细胞及白细胞与血小板之间的粘附。近年来研究发现,选择素及其配体还在精卵识别、滋养层细胞和子宫内膜的相互识别、滋养层细胞侵入、胎盘形成等过程中发挥重要作用。在此,主要对E-选择素、L-选择素及它们的配体在哺乳动物胚胎着床过程中发挥的作用及其表达调节作一综述。 相似文献
6.
测得梅花鹿(Cervus nippon)、坡鹿(Cervuse eldi)、原麝(Moschus moschiferus)和林麝(Moschus berezovskii)线粒体12S rRNA基因全序列,与GenBank中检索到的鼷鹿(Tragulus napu)、长颈鹿(Giraffa camelopardalis)和牛(Bos taurus)12S rRNA基因全序列比对后,以鼷鹿为外群,分别应用ME、ML、MP方法重建系统树,3种树拓扑结构一致.结果显示:①麝、鹿、牛、长颈鹿均各自为单系群;②新反刍下目各上科之间的12S rRNA基因序列分歧为11.6%～16.5%,麝与牛、鹿及长颈鹿的序列分歧(11.5%～13.7%)处于上科的分歧范围(差异不显著,P＞0.94).③麝作为一个单系进化,未与鹿成为姐妹群,而与牛聚为姐妹群(BCL:68%～86%).本研究结果支持Hamilton(1978b),Webb和Taylor(1980)将麝类作为新反刍下目中的麝上科,与鹿上科、牛上科和长颈鹿上科并列的观点. 相似文献
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李红梅 《仲恺农业技术学院学报》2006,19(4):62-67
对蝽次目内总科之间以及蝽总科、缘蝽总科和长蝽总科内的各科等科间的分类和系统发育关系进行了综述．有关蝽次目的系统发育关系，目前大多数学者根据形态学特征的研究一般接受“扁蝽总科＋（蝽总科＋其余的毛点类）”观点．但是各个总科之间，特别是毛点类之间、总科内各科之间的系统发生关系以及皮蝽科的地位还存在争议．迄今为止，从分子水平上对蝽次目系统发育的研究较少． 相似文献
9.
李白的《清平调》三章诗问世千多年来,注释家蜂起,各家所见不一,是三章难解亦难译的诗。作者较深入地研究了本诗,于文中提出了“花人合一”之说,并将其译成英文。本文阐述了作者这一观点:译诗者必须具有译诗的素质,诗是随着时间的不断推移、人类交际空间的不断缩小、人类相互了解的不断深化而越来越可译。 相似文献
10.
Social networks have the surprising property of being "searchable": Ordinary people are capable of directing messages through their network of acquaintances to reach a specific but distant target person in only a few steps. We present a model that offers an explanation of social network searchability in terms of recognizable personal identities: sets of characteristics measured along a number of social dimensions. Our model defines a class of searchable networks and a method for searching them that may be applicable to many network search problems, including the location of data files in peer-to-peer networks, pages on the World Wide Web, and information in distributed databases. 相似文献
11.
Sustaining production and strengthening the agritourism product: Linkages among Michigan agritourism destinations 总被引：3，自引：0，他引：3
Agricultural restructuring has disproportionately impacted smaller US farms, such as those in Michigan where the average farm size is 215 acres. To keep agricultural land in production, entrepreneurial Michigan farmers are utilizing agritourism as a value-added way to capitalize on their comparative advantages, their diverse agricultural products, and their locations near large, urban, tourist-generating areas. Using focus groups, this paper illustrates how entrepreneurial farmers have strengthened Michigan agritourism by fostering producer networks through brochures and web linkages, information sharing in refining the agritourism product, referrals to other agritourism businesses that serve different markets or offer different products, purchase linkages, and a regional approach to establishing agritourism destinations and increase visitation. Successful entrepreneurial, agritourism developers thus work cooperatively, rather than individualistically and competitively. Agritourism destinations facing stiff competition from alternative venues for leisure time and food purchases benefit from supportive linkages that help sustain a critical mass of producers who offer diverse goods, maintain land in agriculture, and thus, reinforce Michigans image for agritourism. 相似文献
12.
GLO3是一种不依赖辅助因子就可分解丙酮醛的酶,有研究表明大肠杆菌的EcHsp31和人的HsDJ 1均属于这种GLO3。丙酮醛是细胞糖酵解过程中产生的一种有毒的副产物,乙二醛酶Ⅰ(GLO1)和乙二醛酶Ⅱ(GLO2)在谷胱甘肽(GSH)的辅助下可以降解细胞内丙酮醛,乙二醛酶Ⅲ(GLO3)不需要GSH的辅助可以直接降解MG。研究真菌的GLO3降解丙酮醛的机制,对认识和研究因丙酮醛引起的疾病具有重要的指导意义。研究表明,真菌中GLO3同源蛋白十分复杂,Hsp31在真菌中广泛存在,DJ 1只在部分真菌中存在,进化树结果支持GLO3的同源蛋白Hsp31和DJ 1是一种趋同进化。对模式真菌酿酒酵母的ScHsp31和裂殖酵母SpDJ 1进行GLO3的酶活测定和HPLC产物检测表明,这两种蛋白均具有GLO3的特性。 相似文献
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14.
Understanding species' interactions and the robustness of interaction networks to species loss is essential to understand the effects of species' declines and extinctions. In most studies, different types of networks (such as food webs, parasitoid webs, seed dispersal networks, and pollination networks) have been studied separately. We sampled such multiple networks simultaneously in an agroecosystem. We show that the networks varied in their robustness; networks including pollinators appeared to be particularly fragile. We show that, overall, networks did not strongly covary in their robustness, which suggests that ecological restoration (for example, through agri-environment schemes) benefitting one functional group will not inevitably benefit others. Some individual plant species were disproportionately well linked to many other species. This type of information can be used in restoration management, because it identifies the plant taxa that can potentially lead to disproportionate gains in biodiversity. 相似文献
15.
叶飞 《农业图书情报学刊》2012,24(4):14-18
研究以随机抽样方式选择11份由各级政府出台的＂十一五＂规划文本为语料,以研究者编制的编码工具对这些资料进行了内容分析,结合分析中各项数据,研究者对＂规划涉及的具体公共文化机构、资源保障与支持途径、规划实施过程中的联动机制、规划目标和规划实施的评估＂等5个方面的问题进行分析和讨论。 相似文献
16.
湖北省栽培植物线虫种类的鉴定(续) 总被引：2，自引：0，他引：2
王明祖 《华中农业大学学报》1988,(4)
五、Hoplolaimidae(纽带科) 1.Basirolaimus Shamsi,1979(基狭纽带线虫属),隶属于Hoplolaiminae(纽带亚科)。1)Basirolaimus indicus(Sher,1963)Shamsi,1979 ♀♀(8)L=980-1200μm a=27-30 b=8-10 b′=6.1-8.0 c=35-40V=52-57% ST=32-36μm ♂(1)L=1040μm a=32 b=9.5 b′=6.8 c=35 c′=1.4 ST=33μm sp.=34μmG=20μm 雌虫:大型虫,体呈圆筒状,稍向腹面弯曲,体环粗,宽1.5-2.0μm。侧线2条,侧带内及其外围有不规则的断续纵纹。唇区半圆形,缢缩明显(图6:1),14-16μm宽,7—9μm高,具有3-4个唇环。唇区常有不规则稍斜生的纵纹,形成大小不均匀的网格,唇基片上有纵纹7-12条。头架强壮并硬化,常呈黄色。口针强大,基部球呈郁金香花瓣 相似文献
17.
After 4 years of operation the NERComP network is now a self-supporting success. Some of the reasons for its success are that (i) the network started small and built up utilization; (ii) the members, through monthly trustee meetings, practiced "participatory management" from the outset; (iii) unlike some networks, NERComP appealed to individual academic and research users who were terminal-oriented and who controlled their own budgets; (iv) the compactness of the New England region made it an ideal laboratory for testing networking concepts; and (v) a dedicated staff was willing to work hard in the face of considerable uncertainty. While the major problems were "political, organizational and economic" (1) we have found that they can be solved if the network meets real needs. We have also found that it is difficult to proceed beyond a certain point without investing responsibility and authority in the networking organization. Conversely, there is a need to distribute some responsibilities such as marketing and user services back to the member institutions. By adopting a modest starting point and achieving limited goals the necessary trust and working relationships between institutions can be built. In our case the necessary planning has been facilitated by recognizing three distinct network functions: governance, user services, and technical operations. Separating out the three essential networing tasks and dealing with each individually through advisory committees, each with its own staff coordinator, has overcome a distracting tendency to address all issues at once. It has also provided an element of feedback between the end user and the supplier not usually present in networking activity. The success of NERComP demonstrates that a distributive-type network can work. Our experiences in New England-which, because of its numerous colleges and universities free from domination by any single institution, is a microcosm for academic computing in the United States-indicate that such networks are best structured in a hierarchical form. This suggests that national networking should be based in part on the more than 30 existing state and regional networks (15). With the groundwork now laid, we expect to see links among existing regional networks to complement development efforts now occurring at the national level. With Greenberger and others, we believe that one or more networking organizations devoted to the management issues discussed in this article will be required to facilitate resource sharing on a national scale. Because of their experience with these problems and their ability to provide service in many areas of the country through existing facilities, regional networks have a major role to play. 相似文献
18.
"关注妇女,抗击艾滋"的"世界艾滋病日"主题,使得全世界将目光聚焦在妇女所受的艾滋病威胁之上。本文笔者在调查河南省部分农村地区艾滋病问题的基础上,运用社会支持理论全面地分析农村女性艾滋病患者社会支持网络的现状,论述了造成其社会支持网络断裂的原因。 相似文献
19.
DsbA, a thioredoxin superfamily member, introduces disulfide bonds into newly translocated proteins. This process is thought to occur via formation of mixed disulfide complexes between DsbA and its substrates. However, these complexes are difficult to detect, probably because of their short-lived nature. Here we show that it is possible to detect such covalent intermediates in vivo by a mutation in DsbA that alters cis proline-151. Further, this mutant allowed us to identify substrates of DsbA. Alteration of the cis proline, highly conserved among thioredoxin superfamily members, may be useful for the detection of substrates and intermediate complexes in other systems. 相似文献
20.
随着科技进步和计算机网络飞速发展,党中央高度重视大学生思想政治工作的创新。本文结合当前时代背景,从多个角度分析研究了大学生恩政网络构建的必要性、可能性及深远意义,详细介绍了河北农业大学信息科学与技术学院“E路同行”网的实际建设和未来规划情况,提出“打造一个平台、实现两大交流、构筑四大栏目、传达五“E理念”,为更好地推进高校思想政治工作网络化提供参考。 相似文献