期刊文献+
共找到49,394篇文章
< 1 2 250 >
每页显示 20 50 100
Co-Occurring Plant Species of the West African Critically Endangered Aubregrinia taïensis Heine, in Côte d’Ivoire
1
作者 Doudjo Noufou Ouattara Hermann Hippolyte Tro +3 位作者 Dofoungo Koné Akoua Emilia Afanvi Doh Amed Coulibaly Adama Bakayoko 《American Journal of Plant Sciences》 2023年第8期915-928,共6页
The Upper Guinea Forest is subject to heavy deforestation. In this context, many endemic and/or rare plant species are threatened with extinction. This is the case of Aubregrinia taïensis (Aubrév. & Pell... The Upper Guinea Forest is subject to heavy deforestation. In this context, many endemic and/or rare plant species are threatened with extinction. This is the case of Aubregrinia taïensis (Aubrév. & Pellegr.) Heine, a critically endangered Sapotaceae species, endemic to Côte d’Ivoire and Ghana. After 3 years of investigation in and around the Tai National Park (TNP) in the West of Côte d’Ivoire, only one individual of this species was located and no sexual reproductive organs (fruits, seeds) were observed. Woody plant species around this individual were inventoried in order to know the species that can co-occur with Aubregrinia taïensis. For that a plot of 30 m of diameter was established around the individual and all of the woody species of this circle were inventoried. Then, the taxonomic diversity, the chorology of the species, the conservation status and their life-form were recorded. A total of 130 woody plant species belonging to 51 families were collected in the site. The most represented families are Euphorbiaceae (12 spp.), Rubiaceae (10 spp.), Annonaceae (7 spp.), Fabaceae, Moraceae, Malvaceae (6 spp. each) while the most represented genera are Diospyros L. (4 spp.), Cola Schott & Endl. and Vitex L. (3 spp.). Species from the Guineo-Congolese Region (GC) are the most abundant (72%). They are followed by West African endemic species (GCW, 19%). Microphanerophytes (mp) are the most abundant and represent more than 40% of the species. Three vulnerable species were found in this plot: Campylospermum amplectens, Placodiscus boya and Trichoscypha cavalliensis. Thus, the preservation of this forest is more than necessary. 展开更多
关键词 Co-Occurring species Aubregrinia taïensis Forest Threatened species Côte d’Ivoire
下载PDF
The Current Conservation Efforts and Future Prospects for the Endangered Nubian Ibex (Capra nubiana ibex) in Sudan
2
作者 Lubna Mohammed Abdallah Hassan Mutasim Essa Abdallah Adam +1 位作者 Latifa Altigani Adam Abakar Nasir Yousif Gaboush Brema 《Journal of Environmental Protection》 2024年第1期39-62,共24页
A comprehensive action plan for the conservation of the endangered species, the Nubian ibex in Sudan, can be developed by gaining a thorough understanding of their current status, conservation strategy, and relevant l... A comprehensive action plan for the conservation of the endangered species, the Nubian ibex in Sudan, can be developed by gaining a thorough understanding of their current status, conservation strategy, and relevant laws and regulations, as well as raising awareness about the importance of protecting endangered species. The Nubian ibex is listed as an endangered species on The International Union for Conservation of Nature (IUCN) Red List, highlighting the need for further research on population conservation efforts due to insufficient population data. To address this knowledge gap, a questionnaire was conducted with various stakeholders, including police officers, researchers, and lecturers, representing a diverse range of organizations and universities. The findings revealed that hunting is the primary factor contributing to endangerment. Mammals account for 80% of endangered species, while reptiles comprise less than one-tenth. Research centers are recognized as the main governing body, and 85% of participants are concerned about the declining population. Hunting accounted for less than half of the threats to the ibex population in Sudan, while habitat loss made up a quarter. Mining, climate change, human activity, and agriculture were also identified as risks. However, there were no plans, strategies, procedures, or measures in place to conserve the Nubian ibex. There were also no initiatives to preserve its biodiversity, and awareness about endangered species was lacking. Although participants believed that laws were effective in protecting the ibex, no licenses were issued for its conservation, and annual surveys were not conducted. Additionally, there were no recorded instances of Mukhalfat related to the Nubian ibex. In light of these findings, we propose various conservation measures to address these challenges. These measures include the implementation of laws and regulations, conducting annual surveys to monitor population trends, protecting habitats, establishing breeding and releasing programs, launching awareness campaigns, undertaking rehabilitation efforts, enhancing research efforts, and developing comprehensive conservation strategies. Additionally, it is crucial to foster cooperation among wildlife institutes to ensure the effective implementation of these conservation measures. 展开更多
关键词 Nubian Ibex SUDAN endangered species Conservation Status Law REGULATIONS AWARENESS
下载PDF
Community structure and species diversity dynamics of a subtropical evergreen broad-leaved forest in China:2005 to 2020 被引量:1
3
作者 Shi-Guang Wei Lin Li +3 位作者 Kun-Dong Bai Zhi-Feng Wen Jing-Gang Zhou Qin Lin 《Plant Diversity》 SCIE CAS CSCD 2024年第1期70-77,共8页
Here,we characterize the temporal and spatial dynamics of forest community structure and species diversity in a subtropical evergreen broad-leaved forest in China.We found that community structure in this forest chang... Here,we characterize the temporal and spatial dynamics of forest community structure and species diversity in a subtropical evergreen broad-leaved forest in China.We found that community structure in this forest changed over a 15-year period.Specifically,renewal and death of common species was large,with the renewal of individuals mainly concentrated within a few populations,especially those of Aidia canthioides and Cryptocarya concinna.The numbers of individual deaths for common species were concentrated in the small and mid-diameter level.The spatial distribution of community species diversity fluctuated in each monitoring period,showing a more dispersed diversity after the 15-year study period,and the coefficient of variation on quadrats increased.In 2010,the death and renewal of the community and the spatial variation of species diversity were different compared to other survey years.Extreme weather may have affected species regeneration and community stability in our subtropical monsoon evergreen broad-leaved forests.Our findings suggest that strengthening the monitoring and management of the forest community will help better understand the long-and short-term causes of dynamic fluctuations of community structure and species diversity,and reveal the factors that drive changes in community structure. 展开更多
关键词 Community structure Death and renewal dynamics species diversity dynamics South subtropical forest
下载PDF
Seedling potential of trees species along the elevational gradient in temperate hill forest of central Nepal
4
作者 DANI Ram Sharan BANIYA Chitra Bahadur 《Journal of Mountain Science》 SCIE CSCD 2024年第4期1329-1344,共16页
Regeneration status of tree species along elevation gradient in temperate hill forest was not understood greatly.Present research examined the tree diversity and its regeneration patterns along an elevation gradient i... Regeneration status of tree species along elevation gradient in temperate hill forest was not understood greatly.Present research examined the tree diversity and its regeneration patterns along an elevation gradient in temperate hill forest,central Nepal.Data were collected from 300 sample plots within vertical elevation bands of 10,ranging from 1365 to 2450 m asl.A random sampling method was used for data collection in three seasons,winter,pre-monsoon and post monsoon seasons.Diameter at breast height(DBH)was used to broadly categorize the plant individual into trees,saplings and seedlings.The tree species richness ranged from 12 to 25 with density of 350 to 1200 individuals per hectare.Species richness of tree and sapling showed statistically significant unimodal pattern,which peaked at mid-elevation.Elevation showed a strong and positive linear correlation with the seedling density(Deviance=0.99,p<0.001)and a significant hump-shaped relationship with sapling density(Deviance=0.95,p<0.001).Similarly,elevations showed a statistically significant negative hump-shaped relationship with all trees,saplings and seedling stages(Deviances=0.89,0.87 and 0.57).The highest values of the Shannon-Wiener index and the lowest value of the Simpson index were found at mid-elevation for all growth forms.Nearly 92%of tree species were found at regenerating stage;49%in a good renewal regeneration status,32%in fair renewal regeneration,and 11%at a poor regenerating condition.Nevertheless,4%of tree species were reported as non-regenerating stages and 4%were newly introduced species.Hence,the regeneration status of the study area was considered fairly well since sapling(78.5%)>seedling(10.6%)≤mature(10.9%).Among tested environmental variables,elevation and annual mean rainfall were the most influential factors in the regeneration of tree species. 展开更多
关键词 Regeneration potential Chandragiri hill Altitudinal gradient species diversity Tree species richness
下载PDF
Climate-change habitat shifts for the vulnerable endemic oak species(Quercus arkansana Sarg.)
5
作者 Suresh Chandra Subedi Seth Drake +1 位作者 Binaya Adhikari Mark V.Coggeshall 《Journal of Forestry Research》 SCIE EI CAS CSCD 2024年第1期117-127,共11页
Quercus arkansana(Arkansas oak)is at risk of becoming endangered,as the total known population size is represented by a few isolated populations.The potential impact of climate change on this species in the near futur... Quercus arkansana(Arkansas oak)is at risk of becoming endangered,as the total known population size is represented by a few isolated populations.The potential impact of climate change on this species in the near future is high,yet knowledge of its predicted effects is limited.Our study utilized the biomod2 R package to develop habi-tat suitability ensemble models based on bioclimatic and topographic environmental variables and the known loca-tions of current distribution of Q.arkansana.We predicted suitable habitats across three climate change scenarios(SSP1-2.6,SSP2-4.5,and SSP5-8.5)for 2050,2070,and 2090.Our findings reveal that the current suitable habitat for Q.arkansana is approximately 127,881 km^(2) across seven states(Texas,Arkansas,Alabama,Louisiana,Mississippi,Georgia,and Florida);approximately 9.5%is encompassed within state and federally managed protected areas.Our models predict that all current suitable habitats will disap-pear by 2050 due to climate change,resulting in a northward shift into new regions such as Tennessee and Kentucky.The large extent of suitable habitat outside protected areas sug-gests that a species-specific action plan incorporating pro-tected areas and other areas may be crucial for its conserva-tion.Moreover,protection of Q.arkansana habitat against climate change may require locally and regionally focused conservation policies,adaptive management strategies,and educational outreach among local people. 展开更多
关键词 Biomod2 Climate change CONSERVATION Habitat loss Habitat shift species distribution modeling Oak species
下载PDF
An unprotected vulnerable relict subtropical conifer-Keteleeria evelyniana: Its forests, populations, growth and endangerment by invasive alien plant species in China
6
作者 Cindy Q.Tang Min-Rui Du +10 位作者 Huan-Chong Wang You-Cai Shi Jia-Le Zeng Shu-Li Xiao Peng-Bin Han Jian-Ran Wen Shi-Qian Yao Ming-Chun Peng Chong-Yun Wang Yong-Ping Li Jordi López-Pujol 《Plant Diversity》 SCIE CAS CSCD 2024年第5期648-660,共13页
Relict subtropical coniferous forests in China face severe fragmentation,resulting in declining populations,and some are under significant threat from invasive alien species.Despite the crucial importance of understan... Relict subtropical coniferous forests in China face severe fragmentation,resulting in declining populations,and some are under significant threat from invasive alien species.Despite the crucial importance of understanding forest dynamics,knowledge gaps persist,particularly regarding the impact of invasive plants on vulnerable natives like Keteleeria evelyniana.In this study,we investigated the impact of invasive plants on the regeneration of forests dominated by K.evelyniana,a subtropical relict species in southwestern China.For this purpose,we characterized forest dynamics of 160 forest plots featuring K.evelyniana as the primary dominant species and determined whether the presence of invasive plants was correlated with regeneration of K.evelyniana.We identified four distinct forest types in which K.evelyniana was dominant.We found that radial growth of K.evelyniana trees is faster in younger ageclasses today than it was for older trees at the same age.The population structure of K.evelyniana in each forest type exhibited a multimodal age-class distribution.However,three forest types lacked established saplings younger than 10 years old,a situation attributed to the dense coverage of the invasive alien Ageratina adenophora.This invasive species resulted in a reduction of understory species diversity.Additionally,our analysis uncovered a significant negative correlation in phylogenetic relatedness(net relatedness index)between native and invasive alien plant species in eastern Yunnan.This suggests closely related invasive species face heightened competition,hindering successful invasion.Taken together,our findings indicate that successful establishment and habitat restoration of K.evelyniana seedling/saplings require effective measures to control invasive plants. 展开更多
关键词 Keteleeria evelyniana Age structure Regeneration species diversity Invasive alien species Phylogenetic relatedness
下载PDF
Detecting the distribution of and public attitudes to charismatic alien species based on media coverage
7
作者 Yuexuan Liu Ruichang Sun +1 位作者 Bo Li Zhijun Ma 《Avian Research》 SCIE CSCD 2024年第3期379-384,共6页
Charismatic species are often reported by the media,providing information for detecting population status and public perception.To identify the number and distribution of free-living Black Swan(Cygnus atratus),a chari... Charismatic species are often reported by the media,providing information for detecting population status and public perception.To identify the number and distribution of free-living Black Swan(Cygnus atratus),a charismatic alien species in Chinese mainland and to detect the public and the media attitudes to the species,we analyzed the reports and emotional tendency from media coverage in 2000-2022 using manual reading,crawler extraction and latent Dirichlet allocation.A total of 6654 Black Swans were reported at 711 sites,including 147 individuals at 30 nature reserves.Successful breeding was reported at one-fourth of the total sites,including five nature reserves.The proportion of positive emotional tendency to Black Swans was overwhelming in the reports and was higher than that to alien species in general,suggesting that the public and the media are unaware of the risk of biological invasion.Effective management of invasive species requires the media clarifies the invasion risk of charismatic alien species.Promoting the unity between the harmfulness of abstract concept of alien species and the charisma of a specific alien species among the public help effective management. 展开更多
关键词 Alien species Biological invasion Cygnus atratus Emotional tendency Invasive species Media coverage Public perception
下载PDF
Species’ geographical range, environmental range and traits lead to specimen collection preference of dominant plant species of grasslands in Northern China
8
作者 Jingya Zhang Cui Xiao +5 位作者 Xiaoyu Duan Xin Gao Hao Zeng Rong'an Dong Gang Feng Keping Ma 《Plant Diversity》 SCIE CAS CSCD 2024年第3期353-361,共9页
Many different factors,such as species traits,socio-economic factors,geographical and environmental factors,can lead to specimen collection preference.This study aims to determine whether grassland specimen collection... Many different factors,such as species traits,socio-economic factors,geographical and environmental factors,can lead to specimen collection preference.This study aims to determine whether grassland specimen collection in China is preferred by species traits(i.e.,plant height,flowering and fruiting period),environmental range(i.e.,the temperature and precipitation range)and geographical range(i.e.,distribution range and altitudinal range).Ordinary least squares models and phylogenetic generalized linear mixed models were used to analyze the relationships between specimen number and the explanatory variables.Random Forest models were then used to find the most parsimonious multivariate model.The results showed that interannual variation in specimen number between 1900 and 2020 was considerable.Specimen number of these species in southeast China was notably lower than that in northwest China.Environmental range and geographical range of species had significant positive correlations with specimen number.In addition,there were relatively weak but significant associations between specimen number and species trait(i.e.,plant height and flowering and fruiting period).Random Forest models indicated that distribution range was the most important variable,followed by flowering and fruiting period,and altitudinal range.These findings suggest that future floristic surveys should pay more attention to species with small geographical range,narrow environmental range,short plant height,and short flowering and fruiting period.The correction of specimen collection preference will also make the results of species distribution model,species evolution and other works based on specimen data more accurate. 展开更多
关键词 Biological specimen Collection preference Dominant plant species Environmental range Geographical range species traits
下载PDF
Biology of Flowering of Some Species of the Genus Phlomoides Moench
9
作者 Mukaddas Kholbutayeva Khislat Khaydarov +1 位作者 Nodira Nurullayeva Abdurakhmonova Ezoza Kakhramon Kizi 《American Journal of Plant Sciences》 CAS 2024年第4期268-273,共6页
The article presents the biology of flowering and the daily dynamics of flowering of two species from the Lamiaceae family: ph. anisochila va ph. sogdiana of the distribution out in the Nuratau Mountains range.
关键词 Phlomoides Rare and Endemic species Nurata Mountain Systems Flowering Dynamics Abiotic Factors CENOPOPULATION
下载PDF
Caulerpa J. V. Lamouroux (1809) (Chlorophyta: Bryopsidales) Species and Sites in Eastern Samar, Central Philippines
10
作者 Ma. Natalia A. Ciasico 《Open Journal of Ecology》 2024年第10期747-753,共7页
A descriptive survey was conducted in Eastern Samar to identify the Caulerpa species, sites where these species exhibit massive populations, and the most preferred edible species. Results revealed that only four of th... A descriptive survey was conducted in Eastern Samar to identify the Caulerpa species, sites where these species exhibit massive populations, and the most preferred edible species. Results revealed that only four of the eleven species, C. racemosa, C. lentillifera, C. chemnitzia var. peltata, and C. cylindracea, have massive populations;The four Caulerpa sites are the municipalities of Arteche, Guiuan, Salcedo (Matarinao Bay) and Quinapondan, and species C. racemosa, C. lentillifera, and C. chemnitzia var. peltata are most preferred edible species which are considered in the local diet. The study concludes that the distribution of Caulerpa in Eastern Samar is area-specific and should therefore be considered in resource planning and management, particularly in relation to aquaculture. 展开更多
关键词 Caulerpa species Caulerpa Sites Caulerpa Massive Populations Edible species Central Philippines
下载PDF
Shells in the cabinet:four new species of Tellinidae(Mollusca:Bivalvia:Tellinoidea)identified from existing South China Sea collections
11
作者 Yuyan ZHANG Junlong ZHANG 《Journal of Oceanology and Limnology》 SCIE CAS CSCD 2024年第2期627-639,共13页
Four species new to science were identified in the Tellinidae museum collections in the Marine Biological Museum of Chinese Academy of Sciences.Pinguitellina triquetra sp.nov.,collected in 1981,has not previously been... Four species new to science were identified in the Tellinidae museum collections in the Marine Biological Museum of Chinese Academy of Sciences.Pinguitellina triquetra sp.nov.,collected in 1981,has not previously been described or reported.It differs from other Pinguitellina species by its trigonal shape,rose-colored valve interior,and deep and wide pallial sinus,which is confluent with the pallial line.Pinguitellina protuberangla sp.nov.has a broad and deep dorsal corner,short and straight posterodorsal margin,comparatively large adductor scars,depressed and fragile shells,and deep socket at the anterior edge of the right valve.Pinguitellina minuta sp.nov.was previously misidentified as Arcopella casta in China.It is a new species based on its unique characteristics,which include small,fragile,inflated,translucent,and triangularly ovate-shaped shells with acuminated and convex umboes.As the first species described in China within the genus Abranda Iredale,1924,Abranda xui sp.nov.has internal ligaments and thin,fragile,and translucent elliptical shells with fine radials on the surface.In this study,we reorganized the species currently contained in the two genera Pinguitellina and Abranda and created keys to the known species.We believe that numerous collected bivalve specimens have been overlooked in the South China Sea,and to date,mollusk has not been adequately sampled.Thus,further exploration and analysis are required to understand species diversity in this area. 展开更多
关键词 Abranda morphology Pinguitellina species diversity taxonomy Tellinidae
下载PDF
Polypore funga and species diversity in tropical forest ecosystems of Africa,America and Asia,and a comparison with temperate and boreal regions of the Northern Hemisphere
12
作者 Heng Zhao Yingda Wu +4 位作者 Zhirong Yang Honggao Liu Fang Wu Yucheng Dai Yuan Yuan 《Forest Ecosystems》 SCIE CSCD 2024年第4期391-400,共10页
Polypores play a cru cial role in energy recycling and forest regeneration in forest ecosystems.The majority of them are wood degraders;some are forest pathogens and others are ectomycorrhizal symbionts.The basidiocar... Polypores play a cru cial role in energy recycling and forest regeneration in forest ecosystems.The majority of them are wood degraders;some are forest pathogens and others are ectomycorrhizal symbionts.The basidiocarps provide food and shelter for many organisms,mostly invertebrates,but also some vertebrates,as well as food and medicine for humans.Despite extensive research on the species diversity and phylogenetic relationships of polypores in recent years,there remains a lack of comprehensive understanding of their distribution patterns and species composition at the large scale.Checklists of polypores from the tropical zone,including tropical Africa,tropical America,and tropical Asia,were analyzed for species diversity,distribution patterns,major taxa,and nutritional modes.A total of 1,902 polypore species was found in the three regions,representing 8 orders,46families,and 250 genera of Agaricomycetes.The orders Polyporales(especially the family Polyporaceae)and Hymenochaetales(especially the family Hymenochaetaceae)had the most prolific taxa,with their species accounting for 93.4%of the total polypores listed.Each of 1,565(or 82.3%)of the total 1,902 species were found in only one of the three regions studied,and we treat them temporarily as"regional endemic species".Only 141species were shared among all three regions,accounting for a mere 7.4%.Tropical Africa and tropical America had the greatest number of shared species and the highest S?rensen similarity index(SC)value.Tropical forests had a higher species richness compared with temperate to boreal forests of the Northern Hemisphere,and in addition,also a higher proportion of white rot polypores compared to brown rot and ectomycorrhizal species.This study outlines the distribution patterns and species diversity of polypores in the world,shedding light on their ecological significance in diverse ecosystems. 展开更多
关键词 AGARICOMYCETES MACROFUNGI species composition Wood-decay fungi
下载PDF
Influence of ion species on extraction characteristicsof mixed ion beams
13
作者 Ao Xu Pingping Gan +1 位作者 Xiang Wan Yuanjie Shi 《Chinese Physics B》 SCIE EI CAS CSCD 2024年第9期444-449,共6页
The spatial distributions of different kinds of ions are usually not completely the same in the process of extracting.In order to study the reason for the different characteristics of ion extraction, a simplified simu... The spatial distributions of different kinds of ions are usually not completely the same in the process of extracting.In order to study the reason for the different characteristics of ion extraction, a simplified simulation model of Cu+ andCr+ ions extraction process was established by 2D3V (two-dimensional in space and three- dimensional in velocity space)particle-in-cell (PIC) method. The effects of different extraction voltages from 0 V to 500 V on the density distribution ofCu+ and Cr+ ions and the change of plasma emission surface were analyzed. On the basis of this model, the ion densitydistribution characteristics of Cu+ ions mixed with Li+, Mg+, K+, Fe+, Y+, Ag+, Xe+, Au+, and Pb+ ions respectivelyunder 200-V extraction voltage are further simulated, and it is revealed that the atomic mass of the ions is the key reason fordifferent ion density distributions when different kinds of ions are mixed and extracted, which provides support for furtherunderstanding of ion extraction characteristics. 展开更多
关键词 EXTRACTION ion species density distribution atomic mass
下载PDF
Morphological and Molecular Data Revealed One New Species of the Short-legged Toads Brachytarsophrys Tian and Hu,1983(Anura,Megophryidae)from Yunnan,China
14
作者 Yanhong HE Renda AI +5 位作者 Junkai HUANG Xianqi LI Xiaolong LIU Junlin LAN Jinmin CHEN Zhiyong YUAN 《Asian Herpetological Research》 SCIE CSCD 2024年第1期22-30,共9页
A new species of the genus Brachytarsophrys,named Brachytarsophrys wenshanensis sp.nov.,has been identified in southeastern Yunnan,China.This new species can be readily distinguished from other known congeners by both... A new species of the genus Brachytarsophrys,named Brachytarsophrys wenshanensis sp.nov.,has been identified in southeastern Yunnan,China.This new species can be readily distinguished from other known congeners by both morphological criterion and molecular analysis of three mitochondrial gene segments:16S,COI,and Cytb.This classification is based on the following morphological characters:(1)medium body size(SVL 83.8–85.1 mm in two adult males);(2)enormous head,with head width nearly 1.2 times the length;(3)tongue pyriform,feebly notched;(4)non-meeting heels;(5)male lacking nuptial pad;(6)tibiotarsal articulation reaching angle of mouth when hindlimbs are extended forward alongside the body;(7)absence of outer metatarsal tubercle,inner metatarsal tubercle elliptic and approximately equal to first toe;(8)rudimentary toe webbing,webbing formula:Ⅰ(2–)–(2^(++))Ⅱ(2^(–))–(3^(++))Ⅲ(2^(½))–(4)Ⅳ(4^(+))–(2^(⅔))V;(9)lateral fringes narrow;(10)dermal ridge or glandular fold on dorsum absent;(11)pectoral glands distinct and irregular,femoral gland small.Our work increases the number of species within the genus Brachytarsophrys to 9. 展开更多
关键词 AMPHIBIANS molecular phylogeny species diversity taxonomy
下载PDF
A new species of Discostella guiyangensis sp.nov.(Bacillariophyta,Stephanodiscales)from Guiyang,China:morphology and phylogeny
15
作者 Yandan XIANG Fangru NAN +3 位作者 Xudong LIU Shulian XIE John Patrick KOCIOLEK Qi LIU 《Journal of Oceanology and Limnology》 SCIE CAS CSCD 2024年第4期1312-1324,共13页
We describe a new species of Discostella from Guiyang based on light and scanning electron microscopic observations,as well as molecular analysis.This species is morphologically distinguished from other species by a r... We describe a new species of Discostella from Guiyang based on light and scanning electron microscopic observations,as well as molecular analysis.This species is morphologically distinguished from other species by a relatively smooth and slightly recessed central area with marginal striae of unequal lengths forked near the margin.Marginal fultoportulae and a single rimoportula are situated between every two costae or on the costae.Both morphological characters and the concatenated data of rbc L and SSU rDNA indicate that Discostella guiyangensis is a unique and new species.According to divergence time estimation analysis,Discostella guiyangensis is the oldest species among the Discostella species sequenced currently.In addition,we complement molecular data of Discostella asterocostata and Discostella stelligera. 展开更多
关键词 Discostella MORPHOLOGY molecular analysis divergence time estimation new species
下载PDF
Distribution and dynamics of niche and interspecific association of dominant phytoplankton species in the Feiyun River basin,Zhejiang,China
16
作者 Shengnan ZHU Zengchuan DONG +6 位作者 Guobin FU Shujun WU Jinyu MENG Weilin LIU Yupeng LIU Xun CUI Yuejiao ZHOU 《Journal of Oceanology and Limnology》 SCIE CAS CSCD 2024年第4期1157-1172,共16页
To investigate the dominant species and interspecific association in the phytoplankton community of the Feiyun River basin in Zhejiang Province,East China,the main stream and the Shanxi Zhaoshandu Reservoir in the dow... To investigate the dominant species and interspecific association in the phytoplankton community of the Feiyun River basin in Zhejiang Province,East China,the main stream and the Shanxi Zhaoshandu Reservoir in the downstream were chosen as the study area,for which 22 sampling sites were designated.Sampling was conducted in September 2021,January,May,and July 2022.Phytoplankton species were identified from both quantitative samples and in-vivo observations.Phytoplankton was quantified by direct counting.Results show that there were 98 species belonging to 6 phyla and 78 genera.In addition,to clarify the niches of the dominant phytoplankton species and their interspecific association,the dominance index was calculated,and a comprehensive analysis was conducted including niche width,niche overlap value,ecological response rate,overall association,chi-square test,and the stability.The phytoplankton community exhibited characteristics of a Cyanobacteria-Chlorophyta-Diatom type community,showing higher diversity in spring and lower diversity in summer.Among 11 dominants phytoplankton species from 3 phyla,both frequency and dominance degree varied seasonally,of which Microcystis sp.was the dominant species in Spring,Autumn,and Winter.The niche widths of the dominant species ranged from 0.234 to 0.933,and were categorized into three groups.The niche overlap values of the 11 dominant species ranged from 0.359 to 0.959,exhibiting significant seasonal differences-highest in winter followed by autumn,spring,and summer in turn.The overall correlation among dominant species in all four seasons revealed a non-significant negative association,resulting in an unstable community structure.A significant portion(84.2%)of species pairs displayed positive associations,suggesting a successional pattern where Diatoms dominated while other dominant species shared resources and space.Despite this pattern,stability measurements indicated that the dominant species community remained unstable.Therefore,careful monitoring is recommended for potential water environment issues arising from abnormal proliferation of dominant species in the watershed during winter.This research built a theoretical foundation with a data support to the early warning of eutrophication and provided a reference for water resources management in similar watersheds along the eastern coast of China. 展开更多
关键词 PHYTOPLANKTON dominant species NICHE interspecific association Feiyun River basin
下载PDF
Optimal Control for Age Distribution and Weighted Size Competitive Species in a Polluted Environment
17
作者 WANG Zhanping 《应用数学》 北大核心 2024年第4期1014-1026,共13页
In the paper,we study an optimal control for a system representing a competitive species model with fertility and mortality depending on a weighted size in a polluted environment.A fixed point theorem is applied to ob... In the paper,we study an optimal control for a system representing a competitive species model with fertility and mortality depending on a weighted size in a polluted environment.A fixed point theorem is applied to obtain the existence and uniqueness exhibited by a non-negative solution of above mentioned model.A maximum principle helps to carefully verify the existence of the optimal control policy,and tangent-normal cone techniques help to obtain the optimal condition specific to control issue. 展开更多
关键词 Optimal control Competitive species POLLUTION Maximum principle
下载PDF
The role of reactive oxygen species in gastric cancer
18
作者 Yuqi Wang Jingli Xu +6 位作者 Zhenjie Fu Ruolan Zhang Weiwei Zhu Qianyu Zhao Ping Wang Can Hu Xiangdong Cheng 《Cancer Biology & Medicine》 SCIE CAS CSCD 2024年第9期740-753,共14页
Gastric cancer(GC)ranks fifth in cancer incidence and fourth in cancer-related mortality worldwide.Reactive oxygen species(ROS)are highly oxidative oxygen-derived products that have crucial roles in cell signaling reg... Gastric cancer(GC)ranks fifth in cancer incidence and fourth in cancer-related mortality worldwide.Reactive oxygen species(ROS)are highly oxidative oxygen-derived products that have crucial roles in cell signaling regulation and maintaining internal balance.ROS are closely associated with the occurrence,development,and treatment of GC.This review summarizes recent findings on the sources of ROS and the bidirectional regulatory effects on GC and discusses various treatment modalities for GC that are related to ROS induction.In addition,the regulation of ROS by natural small molecule compounds with the highest potential for development and applications in anti-GC research is summarized.The aim of the review is to accelerate the clinical application of modulating ROS levels as a therapeutic strategy for GC. 展开更多
关键词 Gastric cancer reactive oxygen species ROSantitumor therapy natural products PHARMACOLOGY
下载PDF
Reactive oxygen species and oxidative stress in acute pancreatitis:Pathogenesis and new therapeutic interventions
19
作者 Chuan-Chao Xia Hong-Tan Chen +2 位作者 Hao Deng Yi-Ting Huang Guo-Qiang Xu 《World Journal of Gastroenterology》 SCIE CAS 2024年第45期4771-4780,共10页
Acute pancreatitis(AP)is a common acute gastrointestinal disorder affecting approximately 20%of patients with systemic inflammatory responses that may cause pancreatic and peripancreatic fat necrosis.This condition of... Acute pancreatitis(AP)is a common acute gastrointestinal disorder affecting approximately 20%of patients with systemic inflammatory responses that may cause pancreatic and peripancreatic fat necrosis.This condition often progresses to multiple organ failure,significantly increasing morbidity and mortality.Oxidative stress,characterized by an imbalance between the body’s reactive oxygen species(ROS)and antioxidants,activates the inflammatory signaling pathways.Although the pathogenesis of AP is not fully understood,ROS are increasingly recognized as critical in the disease's progression and development.Modulating the oxidative stress pathway has shown efficacy in mitigating the progression of AP.Despite numerous basic studies examining this pathway,comprehensive reviews of recent research remain sparse.This systematic review offers an in-depth examination of the critical role of oxidative stress in the pathogenesis and progression of AP and evaluates the therapeutic potential of antioxidant interventions in its management. 展开更多
关键词 Acute pancreatitis Reactive oxygen species Oxidative stress TREATMENT MEDICINE
下载PDF
Impacts of Human Activities and Season on Species Diversity and Abundance of Butterflies in Mpanga Kipengere Game Reserve and Surrounding Farmlands, Tanzania
20
作者 Privatus M. Kasisi Nsajigwa Mbije Paul Lyimo 《Open Journal of Ecology》 2024年第4期274-291,共18页
Maintaining natural habitats is crucial for the preservation of insects and other species that indicate environmental changes. However, the Mpanga/Kipengere Game Reserve and its surrounding farmlands are facing distur... Maintaining natural habitats is crucial for the preservation of insects and other species that indicate environmental changes. However, the Mpanga/Kipengere Game Reserve and its surrounding farmlands are facing disturbance due to human activities, which is putting many wildlife species, particularly larger mammals, at risk. To determine the impact of human activities on butterfly species diversity and abundance in the reserve and its surrounding areas, we conducted a study from November 2021 to October 2023. We collected butterfly data using transect walks and baited traps in two habitat types. Our study yielded 2799 butterfly Individuals ranging in 124 species divided into five families habitat, season, and anthropogenic factors are significant environmental variables influencing species diversity and abundance of butterflies. Therefore, it’s important to protect habitat and dry-season water for the conservation of invertebrates such as butterflies. Our study findings provide essential information for ecological monitoring and future assessment of the Mpanga/Kipengere Game Reserve ecosystem health. 展开更多
关键词 Mpanga Kipengere Game Reserve species Diversity HABITAT Butterflies SEASON Human Activities
下载PDF
上一页 1 2 250 下一页 到第
使用帮助 返回顶部