A knowledge discovery method based on analysis of multiple co-occurrence relationships in collections of journal papers

Purpose: This paper explores a method of knowledge discovery by visualizing and analyzing co-occurrence relations among three or more entities in collections of journal articles.Design/methodology/approach: A variety of methods such as the model construction,system analysis and experiments are used. The author has improved Morris' crossmapping technique and developed a technique for directly describing,visualizing and analyzing co-occurrence relations among three or more entities in collections of journal articles.Findings: The visualization tools and the knowledge discovery method can efficiently reveal the multiple co-occurrence relations among three entities in collections of journal papers. It can reveal more and in-depth information than analyzing co-occurrence relations between two entities. Therefore,this method can be used for mapping knowledge domain that is manifested in association with the entities from multi-dimensional perspectives and in an all-round way.Research limitations: The technique could only be used to analyze co-occurrence relations of less than three entities at present.Practical implications: This research has expanded the study scope of co-occurrence analysis.The research result has provided a theoretical support for co-occurrence analysis.Originality/value: There has not been a systematic study on co-occurrence relations among multiple entities in collections of journal articles. This research defines multiple co-occurrence and the research scope,develops the visualization analysis tool and designs the analysis model of the knowledge discovery method.

The reflection of hierarchical cluster analysis of co-occurrence matrices in SPSS

Purpose： To discuss the problems arising from hierarchical cluster analysis of co-occurrence matrices in SPSS, and the corresponding solutions. Design/methodology/approach： We design different methods of using the SPSS hierarchical clustering module for co-occurrence matrices in order to compare these methods. We offer the correct syntax to deactivate the similarity algorithm for clustering analysis within the hierarchical clustering module of SPSS. Findings： When one inputs co-occurrence matrices into the data editor of the SPSS hierarchical clustering module without deactivating the embedded similarity algorithm, the program calculates similarity twice, and thus distorts and overestimates the degree of similarity. Practical implications： We offer the correct syntax to block the similarity algorithm for clustering analysis in the SPSS hierarchical clustering module in the case of co-occurrence matrices. This syntax enables researchers to avoid obtaining incorrect results. Originality/value： This paper presents a method of editing syntax to prevent the default use of a similarity algorithm for SPSS＇s hierarchical clustering module. This will help researchers, especially those from China, to properly implement the co-occurrence matrix when using SPSS for hierarchical cluster analysis, in order to provide more scientific and rational results.

Spatio-Temporal Variations in Co-Occurrence Patterns of Fish Communities in Haizhou Bay, China: Null Model Analysis

Co-occurrence pattern of fish species plays an important role in understanding the spatio-temporal structure and the stability of fish community.Species coexistence may vary with time and space.The co-occurrence patterns of fish species were examined using the C-score under fixed-fixed null model for fish communities in spring and autumn over different years in the Haizhou Bay,China.The results showed that fish assemblages in the whole bay had non-random patterns in spring and autumn over different years.However,the fish co-occurrence patterns were different for the northern and southern fish assemblages in spring and autumn.The northern fish assemblage showed structured pattern,whereas the southern assemblage were randomly assembled in spring.The co-occurrence patterns of fish communities were relatively stable over different years,and the number of significant species pairs in northern assemblage was more than that in the southern assemblage.Environmental heterogeneity played an important role in determining the distributions of fish species that formed significant species pairs,which might affect the co-occurrence patterns of northern and southern assemblages further in the Haizhou Bay.

Patterns of Mortality Occurrence in a Cardiology Unit of a Low-Income Country: A Critical Analysis at the YaoundéCentral Hospital

Background: In-hospital mortality is high in low-income countries. Currently, little is known in Cameroon concerning the characteristics of patients who die in cardiology units. Our objectives were to determine the in-hospital mortality rate;describe the general characteristics of death patients, and factors associated with mortality. Material and Methods: We conducted a retrospective cross-sectional study by reviewing the medical records of all patients admitted to the cardiology unit of the Yaoundé Central Hospital (CHY) between January 2018 andJanuary 2019. The files of all death patients were studied for socio-demographical, clinical and therapeutical variables. Bivariate analysis was conducted to order to check the association between independents variables and time of death. A p-value < 0.05 was considered statistically significant. Results: A total number of 860 patients were admitted in the cardiology unit of CHY during the study period. Amongst the 860 patients admitted 78 had a fatal outcome, hence, an in-hospital mortality rate of 9.06%. The male gender was predominant amongst the deceased patients (n = 45). The mean age at death was 69 ± 15.19 years. The median time before death was 6 days and they ranged between 1 to 25 days. Hypertension was the most frequent comorbidity (65.4%). Stroke was the principal cause of admission (40.3%), whereas the main presenting complaint was dyspnea (26.9%). Before being admitted to the cardiology department, the majority of the deceased patients were from the emergency department. The major clinical sign of death was respiratory distress (39.74%). Shock on admission was the sole factor found to be associated with the mean time of death (p = 0.012). The patients with deep venous thrombosis compared to other diagnoses were less like to die early (r = 16, p = 0.016). Conclusion: The patient admitted in the cardiology unit of Yaoundé Central Hospital died mainly from stroke and the death is earlier when the patient has signs of shock on admission. These results emphasize the need for a good primary evaluation at the emergency room, to better manage patients with cardiovascular diseases in the cardiology ward.

A Metric Approach to Hot Topics in Biomedicine via Keyword Co-occurrence

Purpose:To reveal the research hotpots and relationship among three research hot topics in b iomedicine,namely CRISPR,iPS(induced Pluripotent Stem)cell and Synthetic biology.Design/methodology/approach:We set up their keyword co-occurrence networks with using three indicators and information visualization for metric analysis.Findings:The results reveal the main research hotspots in the three topics are different,but the overlapping keywords in the three topics indicate that they are mutually integrated and interacted each other.Research limitations:All analyses use keywords,without any other forms.Practical implications:We try to find the information distribution and structure of these three hot topics for revealing their research status and interactions,and for promoting biomedical developments.Originality/value:We chose the core keywords in three research hot topics in biomedicine by using h-index.

Effect of Climate Change on Cotton Lugus lucorum Occurrence Degree

[Objective] The aim was to analyze effect of climate change on occurrence degree of cotton Lugus lucorum in coastal areas of Jiangsu Province, in order to provide authentic references for better prevention. [Method] Statistical analysis was conducted on Information about occurrence degree of cotton Lugus lucorum in Binhai County in Jiangsu Province from 1985 to 2007 under guidance of Integral regression method. [Result] Because of climate change, cotton Lugus lucorum occurrence de- grees differed in different generations and growth stages in Binhai County. Tempera- ture and humidity constituted the main climate factors. In general, climate change hindered occurrence degree from increasing. We could make use of the period when occurrence degree of cotton Lugus lucorum is prone to significant increase and choose some periods, such as early April, late June and middle August, to improve prevention effect. In addition, attention should be paid to comprehensive measures, such as adjustment of industrial structure, which will reduce pesticide and minimize cotton Lugus lucorum damage and adverse impact from prevention measures. [Conclusion] The results provided authentic references for cotton Lugus lucorum preven- tion in Jiangsu coastal areas.

Modes of Occurrence and Cleaning Potential of Trace Elements in Coals from the Northern Ordos Basin and Shanxi Province, China

Based on the analyses of 43 elements in 16 samples of the raw coal and feed coal collected from the northern Ordos basin and Shanxi Province, the modes of occurrence of these elements were studied using the method of cluster analysis and factor analysis, and the cleaning potential of the hazardous elements relatively enriched in the coals was discussed by analyzing six samples of the cleaned coal from the coal-washing plants and coal cleaning simulation experiments. The results shows that the elements Br and Ba show a strong affinity to the organic matter, Cs, Cd, Pb, Zn and Hg partly to the organic matter, and the other trace elements are mainly associated with the mineral matter. Cs, Mo, P, Pb, Zn and S have positive correlations with the two principal factors, reflecting the complexity of their modes of occurrence. Some elements that were thought to show a faint relationship (Be with S and Sb with carbonates) in other rocks are found to have a strong interrelation in the coals. Clay minerals (mainly kaolinite) dominate in the coals, and Ta, Th, Ti, Sc, REE, Hf, U, Se, W, V, Nb, Mo, Al, P, Cr, Pb and Zn are distributed mostly in kaolinite, while K, Rb, Cs, and Na have much to do with illite. Conventional cleaning can reduce the concentrations of most hazardous elements in various degrees. The hazardous elements S, As, Sb, Se, Mo, Pb, Cd and Hg relatively enriched in some coals from the area studied have a relatively high potential of environmental risks. However, by physical coal cleaning processes, more than 60% of As and Hg were removed, showing a high degree of removal, more than 30% of Sb, as well as S, Pb and Cd partly associated with the inorganic matter were removed. Se and Mo showing a relatively low degree of removal could be further removed by deep crushing of the coal during physical cleaning processes, and the concentrations of S, Pb, Cd and Hg with a partial association with the organic matter could be decreased in such ways as the coal blending. Cluster analysis together with factor analysis is a rapid and effective way to deduce the mode of occurrence of an element from bulk samples, and the removability data of most hazardous elements are basically consistent with their modes of occurrence suggested, which indicates that the statistical analysis could predict the cleaning potential of hazardous elements during the physical coal cleaning.

Occurrence Rule and Forecast Method of Cotton Aphid in Poyang Lake Area in Jiujiang City

[Objective] The aim was to explore occurrence rules and forecast methods of cotton aphid in Poyang Lake Area in Jiujiang City to enrich prediction methods of cotton aphid in the area. [Method] The occurrence rules and influencing factors of cotton aphid in Pengze County in 28 years were analyzed with comparative analysis, correlation analysis and wavelet analysis. Furthermore, a long-term forecast model of occurrence grade of cotton aphid and a short-term forecast model of weather condi- tion suitability were established based on stepwise regression. In addition, a forecast test was conducted in cotton area in the north of Poyang Lake. [Result] The wavelet analysis showed that in recent 28 years, oscillating period at 4 years was significant for the occurrence grade of cotton aphid in the north of Poyang Lake, but insignifi- cant for cotton at seedling stage. The comparative and correlation analyses suggest- ed that occurrence of cotton aphid is of significant correlation with winter climate and weather conditions at middle and short periods. The prediction test indicated that long-term forecast model of occurrence grade of cotton aphid and short-term forecast model of weather condition suitability based on stepwise regression can be made use of in the areas with similar climate. [Conclusion] The research provides theoreti- cal references for prevention against cotton aphid in cotton-planting area.

Reliability Analysis of Repairable Systems Using Stochastic Point Processes

In order to analyze the failure data from repairable systems, the homogeneous Poisson process (HPP) is usually used. In general, HPP cannot be applied to analyze the entire life cycle of a complex, re-pairable system because the rate of occurrence of failures (ROCOF) of the system changes over time rather than remains stable. However, from a practical point of view, it is always preferred to apply the simplest method to address problems and to obtain useful practical results. Therefore, we attempted to use the HPP model to analyze the failure data from real repairable systems. A graphic method and the Laplace test were also used in the analysis. Results of numerical applications show that the HPP model may be a useful tool for the entire life cycle of repairable systems.

Analysis of Extreme Precipitation Events over Central Plateau of Iran

This paper describes the results of an analysis of extreme rainfall events in the central plateau of Iran. To study the extreme events, daily records of eighteen stations’ rainfalls in the region for different initial dates up to 2005 gathered from the bureau of meteorology. Then, the extreme rainfall threshold was calculated for each individual station using the statistical index of Gamble type I. Lastly, 22 mm was determined as the extreme rainfall value for the entire stations, and eventually 17 out of 169 extreme precipitation events were extracted in accordance with three factors including a) days with precipitation in not less than 50% of the stations, b) maximum rainfall is 22 mm or more in at least one of the stations, and c) mean precipitation of the basin is more than 3 mm. In the next step to analyze the synoptic features, the relevant meteorological data i.e. relative vorticity, geopotential height, sea level pressure, u and v wind components, relative humidity, vertical velocity, and precipitable water content at multiple levels of the atmosphere were examined from the NCEP/NCAR reanalysis dataset. The synoptic findings indicate that two patterns of deep trough and high ridge of the eastern Mediterranean were responsible for making the heavy precipitation events over the central plateau of Iran. The most and severest rainfall events occurred via deep tough pattern, which covered 76% of days with extreme precipitations during the examined period. Furthermore, the results suggest that the main moisture resources, which identified by HYSPLIT model’s outputs and moisture convergence/divergence zones for the rainy systems in the first pattern (deep trough) including Persian Gulf, Oman Sea, Indian Ocean, and Red Sea, while for the second pattern (high ridge) Persian Gulf and Red Sea play a significant role in feeding the storms in the central regions of Iran. Moreover, the southward movement of Polar Vortex is also considered as those important factors to produce extreme precipitation events over the central plateau of Iran. In general, the HYSPLIT trajectories model’s outputs confirmed the observed synoptic features in particular for the systems’ moisture feeding discussed in the patterns.

A study on clinical nursing research trends and hotspots based on bibliometric analysis

Objective: This study was conducted to understand the trends and research hotspots of clinical nursing in China and abroad, thereby to provide guidance for nursing practice and studies.Methods: We retrieved clinical nursing literature(excluding literature related to psychological nursing and traditional Chinese medicine nursing) cited in Wanfang Data(www.wanfangdata.com.cn) and PubMed between 2007 and 2015 and subsequently performed bibliometric analyses on article volume,journal, clustering of high-frequency keywords, and co-occurrence of keywords.Results: A total of 10374 publications, excluding those related to psychological nursing, were retrieved via a PubMed search. The literature displayed a rising trend in terms of annual publication volume. The journal distribution of clinical nursing publications overall was consistent with Bradford's Law. The main contents of clinical nursing literature between 2007 and 2009 included:(1) studies on effects of the midwife and midwifery methods for natural childbirth;(2) studies on emergency nursing care;(3)studies on dementia care;(4) studies on bandage dressing in trauma nursing; and(5) studies on quality of life in cancer patients nursing. The main contents of clinical nursing literature between 2010 and 2012 included:(1) studies on obstetric nurse-patient relationships;(2) studies on patients' medical team in stroke nursing;(3) studies on cancer nursing methods;(4) studies on nursing patients with trauma related to urinary incontinence; and(5) studies on the quality of life of caregivers of dementia patients.The main contents of clinical nursing literature between 2013 and 2015 included(1) studies on skin care and bandaging in trauma nursing;(2) studies on evidence-based nursing in AIDS care;(3) studies on nurses' role in obstetric nurse-patient relationships; studies on cancer nursing methods;(4) studies on nursing for Alzheimer's disease and dementia; and(5) studies on caregivers and nursing of stroke patients. A Wanfang Data search retrieved a total of 85570 publications, whose volume also exhibited an annual rising trend, in particular with regard to those in core journals. However, percentage of total publication volume, mean cited frequency per article, and total ranking of clinical nursing publications overall displayed a decreasing trend. The main contents of clinical nursing literature between 2007 and 2009 included:(1) diabetes nursing;(2) nursing for cancer;(3) nursing for senility-related diseases;(4)nursing in the event of complications;(5) nursing for hypertension;(6) studies on quality of life after nursing interventions;(7) chemotherapy nursing;(8) studies on compliance after nursing interventions;(9) constipation nursing; and(10) nursing for stroke patients. The main contents of clinical nursing literature between 2010 and 2012 included:(1) diabetes nursing;(2) nursing for cancer;(3) nursing for senility-related diseases;(4) studies on quality of life after nursing interventions;(5) nursing in the event of complications;(6) nursing for hypertension;(7) prevention nursing;(8) perioperative nursing;(9)pain nursing; and(10) studies on compliance after nursing interventions. The main contents of clinical nursing literature between 2013 and 2015 included:(1) diabetes nursing;(2) nursing in the event of complications;(3) cancer nursing;(4) studies on quality of life after nursing interventions;(5) nursing for stroke patients;(6) nursing for the elderly;(7) studies on compliance after nursing interventions;(8)nursing for hypertension;(9) constipation nursing; and(10) prevention nursing.Conclusions: Clinical nursing research in China is in a rapid development stage as defined by Price's law whereby there is a rapid growth in publication volume. By comparison, clinical nursing research in developed countries is in the stable development stage or maturation phase, which is characterized by a flat curve of publication volume and stable development rate. There is a gap of 25-30 years between China and these countries in terms of the growth phases of clinical nursing literature.

Occurrence,sources,and relationships of soil microplastics with adsorbed heavy metals in the Ebinur Lake Basin,Northwest China

There is a lack of research on soil microplastics in arid oases considering the rapid economic development of northwestern China.Here,we studied the occurrence and sources of microplastics in soil,as well as the relationships between microplastics and adsorbed heavy metals in the Ebinur Lake Basin,a typical arid oasis in China.Results showed that(1)the average microplastic content in all soil samples was 36.15(±3.27)mg/kg.The contents of microplastics at different sampling sites ranged from 3.89(±1.64)to 89.25(±2.98)mg/kg.Overall,the proportions of various microplastic shapes decreased in the following order:film(54.25%)>fiber(18.56%)>particle(15.07%)>fragment(8.66%)>foam(3.46%);(2)among all microplastic particles,white particles accounted for the largest proportion(52.93%),followed by green(24.15%),black(12.17%),transparent(7.16%),and yellow particles(3.59%).The proportions of microplastic particle size ranges across all soil samples decreased in the following order:1000-2000μm(40.88%)>500-1000μm(26.75%)>2000-5000μm(12.30%)>100-500μm(12.92%)>0-100μm(7.15%).FTIR(Fourier transform infrared)analyses showed that polyethylene terephthalate(PET),polypropylene(PP),polycarbonate(PC),polyethylene(PE),and polystyrene(PS)occurred in the studied soil;(3)random forest predictions showed that industrial and agricultural production activities and the discharge of domestic plastic waste were related to soil microplastic pollution,in which agricultural plastic film was the most important factor in soil pollution in the study area;and(4)seven heavy metals extracted from microplastics in the soil samples showed significant positive correlations with soil pH,EC,total salt,N,P,and K contents(P<0.01),indicating that these soil factors could significantly affect the contents of heavy metals carried by soil microplastics.This research demonstrated that the contents of soil microplastics are lower than other areas of the world,and they mainly come from industrial and agricultural activities of the Ebinur Lake Basin.

Research on the Probability of Earthquake Occurrence in the Daduhe Drainage Area

This paper applies the Seismic Hazard Analysis method for the cities of China to research on the probability of earthquake occurrence in the Daduhe drainage area,where the cascade dam system is located.This research is based on the potential seismic source scheme of the Seismic Ground Motion Parameter Zonation Map of China(2001),and uses Poisson distribution as an earthquake occurrence model.Earthquake magnitude obeys truncated exponential distribution.The spatial distribution function of the potential seismic source zone is taken as the first-class spatial probability distribution,and the homogeneous probability distribution in the potential seismic source zone as the second-class spatial probability distribution.Considering the seismic intensity attenuation relationship of western China,we compute the occurrence probability of an earthquake around magnitude 6.0(5.5～6.5),7.0(6.5～7.5)and over 7.5 in the Daduhe drainage area,where 22 series cascade dams will be built.The results can be used for hydropower plant planning,hydropower dam site selection and seismic fortification.

Content analysis of documents using neural networks: A study of Antarctic science research articles published in international journals

Content analysis of scientific papers emanating from Antarctic science research during the 25 years period （1980-- 2004） has been carried out using neural network based algorithm-CATPAC. A total of 10 942 research articles published in Science Citation Indexed （SCI） journals were used for the study. Normalized co-word matrix from 35 most-used significant words was used to study the semantic association between the words. Structural Equivalence blocks were constructed from these 35 most-used words. Four-block model solution was found to be optimum. The density table was dichotomized using the mean density of the table to derive the binary matrix, which was used to construct the network map. Network maps represent the thematic character of the blocks. The blocks showed preferred connection in establishing semantic relationship with the blocks, characterizing thematic composition of Antarctic science research. The analysis has provided an analytical framework for carrying out studies on the con- tent of scientific articles. The paper has shown the utility of co-word analysis in highlighting the important areas of research in Antarctic science.

原位微区分析华北典型富锂煤中关键金属赋存规律

煤是特殊的沉积有机岩石,在其形成过程的特定地质条件下,可以富集战略性金属,并在煤系中形成大型或超大型金属矿床。目前已经在华北聚煤区多处煤田发现煤系锂矿化现象,为了查明锂的载体及其赋存规律,本文在矿物组成分析的基础上,采用微区原位分析的方法研究了不同矿物和显微组分中关键金属的赋存特征,为煤系关键金属的富集成因和勘查提供了新的思路。研究结果表明:高岭石是煤中锂的最重要载体,表现为Li-Ga、Li-Zr-Nb-Hf-Ta和Li-Y-Sr不同的元素组合特征,分别代表碎屑物源控制型、火山灰输入型和流体活动参与型三种不同的关键金属富集成因类型。镜质结构体中富集Zr-Hf-Th元素组合,胶质结构体表现为轻度的Li富集;脉状含钠黏土矿物富集Ga-Ba-Tl,脉状磷灰石表现为Ba-Sr-Y富集特征,这些脉体矿物元素的富集是成煤后期流体活动的产物。

基于CiteSpace可视化图谱的污泥土地利用现状研究分析

以2010—2020年间Web of Science(WoS)核心合集和中国知网(CNKI)数据库为数据源,运用CiteSpace软件对污泥土地利用研究发文量、研究力量和研究热点进行计量可视化分析,旨在探析当前国内外研究现状,探索前沿动态和未来发展趋势。结果表明,污泥土地利用研究总发文数量变化幅度较小,该领域研究热度处于平稳状态;在两大数据库中,美国和中国是该领域中合作研究多且影响力大的国家,最活跃的研究机构是中国科学院,作者及研究团队间的合作相对较少;国际上污泥土地利用研究趋于多元化发展,而我国在该领域的研究方向则比较单一,偏重于重金属研究。基于文献共现聚类和研究热点分析,提出污泥土地利用研究的未来展望:在多个层面开展合作研究,积极研发无害化污泥土地利用技术,全方面跟踪监测和评估污泥土地利用对陆地生态系统的影响,多部门联合制定污泥土地利用相关政策和技术规范。

表生水土环境铊污染成因研究现状与发展趋势

铊(Tl)是一种有毒的重金属,对人类的危害超过了汞、镉、铅、锌、铜等传统致毒重金属元素。本文总结了铊的元素特征及其地球化学行为、含铊矿床的全球分布及其成矿时代,对比分析了铊在三大类岩石中的分布差异性,系统回顾了铊的毒理性及其致病机理、铊污染源解析与示踪、表生环境铊的迁移与转化。通过研究发现,铊在三大类岩石中均有分布,且岩浆岩中铊元素呈规律性分布。铊与热液矿床关联性强,主要富集于与低温热液矿床有关的铅、锌等矿床中,且优先进入硫化物熔体,致使含硫化物矿床铊浓度较高。总体而言,我国土壤铊污染与铊矿产分布均具有“南高北低”的特征,显示铊污染与铊矿床的开采和冶炼具有显著关联性。水体中铊主要以Tl^(+)进行迁移,Tl^(+)可替代K^(+)进入黏土矿物,或通过微生物作用氧化成Tl^(3+)。铊从土壤中通过植物根系进入植物体后,将不均匀地分布于植物体内,^(203)Tl更容易向细胞膜表面动态扩散,植物根系优先吸收较轻的铊同位素(^(203)Tl),较重的铊同位素(^(205)Tl)留于生长层。通过对比铅与铊同位素示踪法,发现铊同位素法对于示踪物质来源及其迁移过程具有响应速度快、敏感性强等优势,但铊同位素技术的提升还有待铊同位素数据库的进一步完善。铊污染形成演化时空模拟是揭示污染来源、污染过程与发展趋势以及开展区域风险评估的重要手段,但数据获取、模型选择与验证、不确定性分析以及系统集成与决策支持等问题均有待进一步加强研究。

眼斑双锯鱼(Amphiprion ocellaris)发育中体色花纹时序发生的色素细胞变化和控制基因表达的分析Ⅱ.仔稚幼鱼时期

眼斑双锯鱼(Amphiprion ocellaris)属于鲈形目、雀鲷科、双锯鱼属,是热带珊瑚礁观赏鱼类的首选品种,其不同发育时期各种色素细胞的动态变化及其控制基因表达情况有待深入研究。记录了眼斑双锯鱼仔稚幼鱼体色花纹模式建成的发育过程,对比不同发育时期体色变化的特点,筛选出仔稚幼鱼时期体色花纹变化较为明显的9个发育时期,并利用荧光定量PCR检测了眼斑双锯鱼各发育时期的10个体色控制基因的表达情况。结果显示:眼斑双锯鱼的体色发生存在明显的时序性,仔鱼时期鱼体呈现半透明状,黑色素细胞排列在身体两侧,随着生长发育数量逐渐增多;稚鱼时期,体表开始出现红色素细胞和黄色素细胞,身体慢慢变得不透明,9 dph开始出现第一道条纹,虹彩色素细胞数量逐渐增多,10 dph时期观察到第二道条纹出现;幼鱼时期,三道白色条纹完全形成,体表的橙红色和白色条纹被黑色素细胞分隔开来,界线逐渐清晰,长成完整的花纹。结合荧光定量PCR结果分析发现:在仔稚幼鱼阶段,10个体色控制基因在各发育时期均有表达,不同功能分类的基因在不同发育时期的表达变化趋势差异较大,在仔稚幼鱼前期表达量变化较大的基因主要为TYR、Dct、Ednrb、Sox10等与黑色素细胞迁移、分化、合成相关的基因;随着幼鱼不断的生长发育,白色条纹逐条出现,与虹彩色素细胞相关的Fms、Foxd3等基因也开始出现表达量显著上升的趋势。

光伏产业政策叙事主题时序演化特征研究

首先,定义光伏产业政策叙事的3W框架,抽取光伏产业政策结构化内容,基于词频-逆文档算法,挖掘2011—2022年光伏产业政策叙事主题关键词;其次,采用共现网络方法,可视化分析光伏产业政策叙事主题;最后,耦合时序要素,对应分析光伏产业政策叙事主题焦点。结果表明:2011—2019年光伏产业政策叙事主题聚焦于推广分布式光伏应用、解决光伏消纳等问题,而2020—2022年光伏产业政策叙事主题逐渐转向提升储能、保障消纳等方面。省域政策对国家政策的执行度较高,政策主题基本保持一致,但省域政策会根据自身发展实际因地制宜地施策,各地发展方向均有所侧重。从对应分析来看,不同阶段国家政策的叙事主题以及不同阶段省域政策的叙事主题均存在显著差异。省域政策年际间衔接紧密,政策执行力度强,政策寿命长;国家层级与省域层级的叙事主题和时间变量之间都存在非连续的局部相关性。

基于高压汞灯荧光显微观测的剩余油定量分析方法

为明确不同驱油阶段微观剩余油的分布状态,指导老油田在注水开发后期的剩余油挖潜,选取典型区块不同渗透率级别的岩心进行了驱油试验,采用液氮冷冻技术制作岩心薄片并利用高压汞灯荧光显微镜,分析了饱和油阶段、水驱至模型初见水阶段和水驱结束后阶段的微观剩余油赋存状态。经过图像处理,细分了剩余油赋存状态,并计算了不同状态剩余油的赋存比例。研究表明,中渗透率岩心水驱主要动用了自由态剩余油,水驱后残存的自由态剩余油较多,可作为继续挖潜对象;低渗透率岩心水驱过程中自由态微观剩余油含量进一步减少,水驱后束缚态的膜状剩余油及半束缚态的喉道状剩余油可作为接替开发对象。高压汞灯荧光显微观测法为剩余油分析提供了一种新的量化方法,可以为老油田的剩余油挖潜提供借鉴。