1 Interoduction

Microorganisms maintain the dynamic balance of the biosphere in the process of material cycling in nature,and many microorganisms maintain symbiotic or epiphytic relationships with marine animals and plants.The symbiotic microorganisms in marine animals and plants show unique metabolic pathways and physiological activities due to their different host environments.Co epiphytic microorganisms are considered as the important source of natural active products[1].At present,it’s found that many marine bioactive substanceswereisolated from marine microorganisms,and found some previously considered bioactive substances of marine animals and plants produced are actually composed of plant and animal host commensal microorganismsproduced.Marine microorganism is a huge treasure house for searching natural active substances.Its special living environment and ecosystem make its metabolites many novel structures and surprising biological activity.Based on this,marine microbial metabolites will greatly promote the discovery of new drugs[2-4],environmental protection,biological materials,aquaculture and other fields.

2 The sources of data

Literature data from the retrieval results of China National Knowledge Infrastructure CNKI database,with the retrieval time ranged from 2001 to 2016,and the retrieval date on May 30,2017,is hired in the present study.As comprehensive as possible to search the epiphytic microorganisms in marine research in the related literature,the retrieval 1"set theme:epiphytic microorganisms and theme:epiphytic marine microorganisms,to be consistent with the retrieval type paper which consists of 102,and the paper carries on the statistical analysis from the published annual distribution,research level distribution,keywords,research institutions,fund sources,subject distribution,source distribution and so on;at the same time,retrieval 2"set theme:epiphytic microorganisms of marine microorganisms,to analyze the epiphytic microorganisms of microorganisms accounted for the proportion of research.Thomson Data Analyzer software is used to visually analyze the correlation degree of subject words according to the frequency of occurrence.

3 Infusions and analysis

3.1 Document overview

When the retrieval strategy was set up as retrieval set 2 102 papers on symbiotic and epiphytic microorganisms were obtained,and only 94 papers were retrieved with the retrieval set 1,accounting for 8.8%of the total number of related research papers on epiphytic marine microorganisms.Papers were published in the past 1 year,as shown in Fig.1,and a research paper was published in 2001,which is the screening of Marine Actinomycetes against tumor active strains.In 2009,only one research paper was published,while 2012 had 17 articles;from 2010 to 2015,the total number increased by 70.2%,showing the enthusiasm of researchers in this field study.Among them,Guo Shoudong's 2010 doctoral dissertation at the Ocean University of China was cited with the highest frequency (25 times).However,since 2016,the number of related literatures has dropped to 4,and no more than 4 articles are expected in 2017.This may be related to the development of new antimicrobial agents.

3.2 Keyword analysis

The key words of the literature can reflect the content,methods and objects of the study,and the focus of the research can be seen from the distribution of high-frequency keywords.In this study,the key words of 94 research papers were searched,and the synonymswerecleaned manually accordingtothemeaningof keywords.Marine microorganisms,secondary metabolites,biological activity of keyword frequency is high,but they are searching words whichis to be excluded,and ultimately determine the characterization of epiphytic marine microorganisms on the appearance frequency and in accordance with the metabolites of strain,type,function,resistance identification,structure analysis and classification.It can be seen from Fig.2,a total of epiphytic marine microbial research focus mainly concentrated on the antibacterial activity and biological activity of antioxidant activity,in addition to the analysis of isolation and identification of strains,optimization of fermentation conditions such as the theme of the study;the major strain including sponges,marine fungi,actinomycetes,marine microorganisms;structure analysis mainly including the structure characteristics,structure identification and chemical analysis etc.Based on the statistical sorting of CO word,the key words of these searches can get the visualization graph of association between keywords(Fig.3).

公路桥梁工程上部构造加固是其加固质量控制的核心所在。具体而言，构件截面扩大、纵梁增设是其加固的两种基本方式。就构件截面扩大过程而言，桥面补强法、配筋加固法、粘贴炭纤维布加固法等都是其常用的技术应用形式[3]。相比而言，桥面补强的操作较为简单，且经济成本较低；而配筋加固法在加固质量方面具有突出优势；此外，在力学性能、化学稳定性、材料质量和施工操作方面，粘贴炭纤维布加固法的应用效果较为突出。实践过程中，工程建设人员只有系统掌握这些加固方式的应用要点，并在工程加固指标的基础上，进行加固技术的高效化、结合应用，才能实现其加固质量的有效提升，从而确保工程管理经济效益和社会效益的有效获得。

Fig.1 Annual growth of papers included in CNKI database

Fig.2 The distribution of keywords in epiphytic marine microbial research

The dots in Fig.3 represent the topic of study.The connection between dots and their distances represents the degree of association between the contents of each other.The closer the line is,the closer the distance is,and the higher the correlation between them is.It issuggested that there isa strong association between extracellular polysaccharide and antioxidantactivity,extracellularpolysaccharide and structural characteristics between marine microorganisms and extracellular polysaccharides,indicating that there is a large correlation between these research hotspots.

Fig.3 The association visualization graph of Keywords

3.3 Research field and periodical distribution

The distribution of the top 16 important journals in the paper is shown in Figure 5,and the most published papers are from Ocean University of China.A total of 21 papers were published,accounting for 32.3%of the total number of publications.The Journal of Microbiology,Biotechnology Bulletin,Taiwan Strait and Marine Bulletin are the core Chinese journals in the field of marine science.The number of publications in these journals is basically the same,and the impact factors are also less significant.Data show that in the epiphytic marine microbial research,Ocean University of China and Xiamen University are the main contributors to the publications,while Ocean University of China research mainly focuses on the epiphytic marine microbial structure and active substances,and Xiamen University mainly engaged in metabolic and chemical composition analysis.This is probably related to the difference of marine resources between the south and the north China.

Fig.4 The distribution of subjects

Field and periodical distribution of the core Chinese statistical retrieval,and statistical analysis were made according to the published by major subject areas (Fig.4)and the distribution of important source journals were collected and analyzed (Fig.5).Data show that biological and pharmaceutical research papers involved in many subjects,of which the most published subject of traditional Chinese Medicine published a total of 38,accounting for 37.6%of the total number of publications.The subject area of biology is secondary,and 27 papers were published,accounting for 26.7%of the total number of publications.Among the top five subjects,a total of 83 papers were published,accounting for 88.3%of the total number of publications.Biology,environmental science and resource utilization,and fisheries were paid more attention to in the field of marine microbiology.

Fig.5 The distribution of literature sources

3.4 The analysis of research level

According to Fig.7 and Fig.8 analysis,author and research institutions ranked in the top five,in addition to Shanghai Jiao Tong University and other institutions from marine research field,Ocean University of China ranked first,and the contribution rate was 31.9%;followed by Guangdong Ocean University,Xiamen University and the Chinese Academy of Sciences Institute of Oceanography,and the contribution rate were 5.3%,4.3%and 4.3%,respectively.

According to Fig.9 the source of fund is mainly from national science foundation.There are 30 articles from the National Natural Science Foundation,totallying 31.9%;the second issupported by the National High Technology Research and Development Program of China,accounting for 20.2%of the total number,the National Key Basic Research and Development Foundation,the Natural Science Foundation of Shandong Province,the doctoral program of higher education fund contribution rate were 5.3%,3.2%and 3.2%,respectively.

3.5 The analysis of author sources and research institutions

Fig.6 The study of hierarchical distribution

It can be seen from Figure 6 that the symbiotic marine microorganisms are mainly divided into four research levels,and the basic and applied basic research is the most important source of publications,which published 79 papers,accounting for 87.7%of the total number of publications.

Fig.7 The author's distribution

3.6 The analysis of project fund sources

其遵循“磁阻最小原理”，定子绕组通电后，磁路有向磁阻最小路径变化的趋势。当转子凸极与定子凸极错位时，气隙大、磁阻大，一旦定子绕组通电，就会形成对转子凸极的磁拉力，使气隙变小，磁路磁阻变小。与此同时用电子开关按一定逻辑关系切换定子绕组的通电相序，即可形成连续旋转的力矩。开关磁阻电机调速系统的调速功能是由开关磁阻电动机转子位置检测器、功率变换器和控制器（微处理控制器）共同配合实现的。

Fig.8 The distribution of research institutions

Fig.9 The distribution of project fund sources

4 Expectations

例13标题中的Ties That Bind（收紧绳索）比喻通过政策工具来发展有益于竞争的专利联营；此外，Pool（水池、联营）具有双关，在译文中译为联营。例14也是运用比喻来表明KSR案所确立的专利法上“显而易见性”（我国专利法称“创造性”）标准的荒谬性，但如果直译该修辞，则汉译后的标题过长且与译文的正式文体不太协调。译文根据论文的观点，将设问句改译为陈述句，观点明确、语言庄重。

Bibliometric studies for a subject may be influenced by the type of database,the key words,the time of retrieval,and the tools of statistical analysis.

This article uses the literature metrology method for the two time analysis of epiphytic marine microorganisms related literature,the overall situation to help fishery science and technology workers,producers,marine biologists and marine drug production enterprises to understand and grasp the domestic epiphytic marine microbial research,understand the dynamic mechanism and its related research areas,strengthen academic exchanges in the field and effectively carry out cooperation,inspire new research ideas and new researches.

All the data are from the CNKI database,but because of the different retrieval conditions,it may be different from the other two research results.Due to the author's knowledge level in the field of research,the analysis of the literature inevitably has omissions,and the analysis of the details is not perfect,which needs further study.

1.3 资料收集与统计学处理 由培训合格的调查员按调查计划参与角膜移植专科门诊复诊工作，对符合条件的患者进行问卷调查，如实填写调查表。调查结束后，进行5%左右的问卷复查，以核准调查信息的准确性。所得数据运用 SPSS 16.0软件进行统计学分析。

Uncertainties exist in this paper analyzes: (1)retrieval style setting cannot fully include the target literature,and different articles have multiple expressions of the same meaning,and words are diversified;(2)domestic scientific research continuously updated literature database,thus with time goes by,retrieval needs to be conducted again given the fact of new literature,and literature increased in a certain field the study can only be locked in a specific time range;(3)the existence of error analysis,such as the different authors with the same name confusion or the same author who mistakenly to be viewed as different authors and other circumstances.

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