首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 156 毫秒
1.
Bifurcation,Chaos and Control in Nervous System   总被引:2,自引:2,他引:0  
Bifurcation,Chaosand ControlinNervousSystemGongYunfan(龚云帆);XuJianxue(徐健学)(DepartmentofEngineeringMechanics,Xi'anJiaotongUnive...  相似文献   

2.
东北地区中生代化石木异木属及其古生态   总被引:5,自引:0,他引:5  
迄今为止,我国共了现异木属(Xenoxylon)化石木10种(包括2新种),它们是X.latiporosum,X.conchylianum,X.liaoningense,X.japonicum,X.ellipticum,X.hopeiense,X.peidense,X.yixianense,X.fuxinense sp.nov.,X.huolinhenese sp.nov.。文中对该属的古生态作了  相似文献   

3.
兴安盟山杏灌木草原的排序王晓江,章中,刘永军,章海波(内蒙古林业科学研究院,呼和浩特010010)OrdinationofPrunussibiricaShrub-SteppesinXinganLeague,InnerMongolia¥WangXiaojiang;ZhangZong;LiuYongjun;ZhangHaibo(InnerMongoliaAcademyofForestrySciences,Huhhot010010).Chi-neseJournalofEcology,1993,12(1):29-32。ThePrunussibiricashrub-steppesinXinganLeagueofInnerMongoliaarestudiedusinganumberofor-dinationmethods,includingpolarordination(PO),principalcomponentanalysis(PCA)ordinationandcorrespondenceanalysis(COA)ordination,22poltsofPrunussibiricashrub-steppesarec  相似文献   

4.
BIOLOG系统鉴定黄瓜根围促生菌的初步研究   总被引:8,自引:0,他引:8  
对筛选出的8株具有明显促生防病作用的黄瓜根围促生菌CN11,CN31,CN45,CN1 16,CN129,XB120,XB5,XB41通过BIOLOG法进行了分类鉴定,分别为:铜绿假单胞菌(Psendomonas aeruginosa),波纹假单胞菌(P. Corrugata),短芽孢杆菌(Bacillus brevis),荧光假单胞菌B型(P. Fluorescens type B),铜绿假单胞菌(P. Aeruginosa),荧光假  相似文献   

5.
马铃薯Y病毒复制酶基因的克隆和序列分析   总被引:6,自引:0,他引:6  
马铃薯Y病毒复制酶基因的克隆和序列分析彭学贤,项瑜,刘俊君,莽克强(中国科学院微生物研究所,北京1000080)MolecularcloningandsequenceanalysisofPVYNIbgene¥PenXuexian;XiangYu;Li...  相似文献   

6.
我国自然保护区的生态旅游开发   总被引:42,自引:0,他引:42  
我国自然保护区的生态旅游开发袁兴中,刘红,高天刚(山东曲阜师范大学273165)DevelopmentofEcotourisminNaturalReservesofChina¥YuanXingzhong;LiuHong;GaoTiangang(Quf...  相似文献   

7.
QuantitativeChangesinMainParametersofSecondaryXylemduringAgingProcessinPinusbugeanaLINJin-xing;(林金星),LINYue-hui;(林月惠),WEILin-...  相似文献   

8.
视网膜色素变性(retinitis pigm entosa,RP)是一组与多个基因相关而任一单基因突变可致病的视网膜退化疾病,是造成失明的常见病因之一。患者多初起夜盲,随之发现周边视野逐渐缩小,成为管状视野,最终至完全失明。它以视网膜进行性感光细胞和色素上皮功能丧失为共同表现。临床上以眼底色素沉着和视网膜电图异常或无波为特征。不同基因所致的RP病在临床上无特征性差异。全球约有400 万人患有此病,我国的发病率约是1/3500。该病的遗传方式有:常染色体隐性(Autosom alRecessive,AR);常染色体显性(Autosom alDom inant,AD);X连锁隐性(X-linkedRecessive,XR)和X连锁显性(X-linked Dom inant,XD);Y连锁RP家系也有报道。X连锁RP发病率较低,在我国约为7.7% (美国为6% ),但它发病早,进展快,病情严重,30- 45 岁就有严重视力损伤甚至失明。临床上大部为隐性,散发病例可以认为属于隐性遗传,因为无先辈病史的患者可以认为是新突变,无后代患者的不会是显性遗传,而隐性纯合体患者的配偶若不携带同一突变基因,则后代无患者,本人于是表现为散发。未成年无家史患者则难以判断。照此计算,这部分约占患者总数的81.3% (美国为84% );其次为常染色体显性遗传,约占11% (美国为10% )[1,2]。已发现的RP相关基因有27个。位于X染色体上的RP基因有5 个。RP3 位于X染色体短臂Xp21.1,是一种隐性遗传RP病。RPGR(retinitis pigm entosa GTPase regulator,视网膜色素变性GTP酶调节物)基因是RP3的致病基因,已于1996 年被克隆 。  相似文献   

9.
人乳头瘤病毒研究的新进展   总被引:2,自引:0,他引:2  
人乳头瘤病毒研究的新进展于修平,卞继峰(山东医科大学微生物学教研室,济南250012)ResearchProgressonHumanPapillomaViruses¥YuXiuping;BianJifeng(DepartmentofMicrobiol...  相似文献   

10.
InsituLocalizationandIsolationofActinFilamentsfromPollenTubesofAmaryllisvittataAitCAlXue(蔡雪);DONGYun-zhou(董云洲)(CollegeofLifeS...  相似文献   

11.
研究香溪河大型底栖无脊椎动物群落结构和季节动态特征情况,发现高翔蜉、萝卜螺、河蚬、湖沼股蛤、四节蜉为香溪河水系优势分类单元,各季节底栖动物优势种的组成存在显著差异。冬季的生物密度、生物量、生物多样性指数显著高于其他季节,说明冬季的河流生境最适宜大型底栖无脊椎动物生存。香溪河刮食者丰度最高,撕食者最低,表明香溪河着生藻类丰富;固着型底栖动物在香溪河底栖类群中丰度最高,说明香溪河河流流速较快,生境更适宜固着型动物栖居。不同季节环境因子对大型底栖动物群落结构有显著影响。  相似文献   

12.
《Acta Oecologica》1999,20(4):333-342
The suprabenthic fauna of the Mondego river estuary (western Portugal) was sampled monthly between June 1996 and June 1997. Quantitative samples were taken, with a suprabenthic 500-μm mesh size net, at regularly spaced stations covering the entire south arm of the estuary. The diversity of the samples and the distribution of the species were assessed. Suprabenthic communities were identified using a divisive multivariate statistical technique and species composition, density and biomass of the dominant species of each community were compared among communities. Diversity was highest in the mouth of the estuary where density and biomass were lowest. Diversity decreased upstream and was lowest in the mid and inner estuary where density and biomass reached maximal values. Suprabenthic animals, mainly the mysid Mesopodopsis slabberi, reached high densities in inner and upstream stations, whereas the more seaward stations had lower densities but a higher number of species. The spatial patterns dominated over the temporal patterns.  相似文献   

13.
珠江口底栖动物生态学研究   总被引:20,自引:1,他引:19  
采泥样调查所获底栖动物一般为体形较小,活动能力较弱的种类,往往是一些底层鱼类和虾类等良好的天然饵料。珠江口海域渔业资源丰富,是中国南海区的主要渔场之一,因此,对该海域饵料底栖动物进行研究有重要意义。通过1999年9月和2000年4月分别对珠江口底栖生物进行的两个航次的采泥样调查,分别鉴定出底栖动物15衙睡21种,共计32种。底栖动物的优势种,秋季为光滑河篮蛤Potamocorbula laevis(Hinds)(Y=0.387),春季为光滑河篮蛤(Y=0.464)和欧虫Owenia fusformis Delle Chiaje(Y=0.120)。平均个体数量和生物量,春季为591.7ind./m^2和26.7g/m^2,秋季为85.0ing./m^2和7.4g/m^2;而在各类群生物中,软体动物占绝大部分,其次为多毛类,其它各类群所占比例都不足5%。生物多样性,个体数量和生物量的分布均呈由北向南增加的趋势。另外,与近20a中的历史资料相比,珠江口底栖动物个体数量变化不大,除2000年春季较高为591.7ind./m^2外,其变化范围在72.4-128ing./m^2之间。春季生物量除1991年较高为27.0g/m^2外,变化不是很大,大约10g/m^2;但秋季生物量呈明显下降趋势,1980年为30.1g/m^2,1990年为27.8g/m^2,1999年秋季急剧下降至7.4g/m^2。此外,从底栖动物各大类群的百分组成变化情况来看,一般以软体动物个体数量(22.7%-83.2%)和生物量(57.9%-82.5%)都最高;多毛类的个体数量百分组成占第二倍,其范围是13.4%-52.3%;其它各类群的百分组成除个别时候所占比例较大外,一般都较小。  相似文献   

14.
At three stations in the shallow Semyachik Lagoon, Kronotskii Bay, Kamchatka, 72 species and intraspecific taxa of microalgae were found. Diatoms (55) were the dominant group. In the qualitative and quantitative respects, phytoplankton was mainly represented by casually planktonic (benthic) species of diatoms. The general features of diel dynamics of phytoplankton were similar at the three stations and depended on the fluctuations of the level of tidal currents. The highest biomass (up to 363 mg/m3) and density (up to 66000 cells/I) were observed between 12∶00 and 18∶00 at low tide; these characteristics were an order of magnitude lower than at high tide.  相似文献   

15.
乐清湾大型底栖生物群落特征及其对水产养殖的响应   总被引:8,自引:0,他引:8  
乐清湾大型底栖生物的四季采样研究。发现124种大型底栖生物,其中多毛类41种、软体动物37种、甲壳类22种、棘皮动物10种和其他类14种。乐清湾大型底栖生物年均生物量41.95g·m^-2年均密度85个·m^-2,生物量棘皮动物居首(约占60%);密度软体动物最大(约占35%)。生物量和密度分布春季为最高。对乐清湾大型底栖生物分布现状与以往资料及邻近海湾进行了比较,并将大型底栖生物群落对乐清湾牡蛎养殖和网箱养殖的响应做了分析探讨。  相似文献   

16.
Despite the dynamic nature of spatial pattern, the temporal variation of spatial structure of marine benthic assemblages is rarely assessed using several temporal scales. We quantified the variability of density and biomass of main benthic species in the intertidal soft-bottom flats at two bights in Chupa Inlet (Kandalaksha Bay, the White Sea). The data cover the 21-year period (1987–2008) of a long-term monitoring survey (1987–present) using a hierarchical sampling design with two temporal (year, season within a year) and three spatial scales (bights—7 km, stations within a bight—10–100 m, and replicate samples—10 s cm apart). We used nested ANOVA to test significance and variance components to compare the relative contribution of different scales of variability of density and biomass of 18 most occurring macrobenthic species. Some species demonstrated high large-scale variability, however, the majority showed high small-scale variability and residual variance. The interactive variability was at least as important as the temporal effects, indicating that the spatial pattern changes through time. The assemblages were more variable at small scales and more stable at larger scales. Potential implications for sampling design are discussed.  相似文献   

17.
Marine benthic communities are effective indicators of environmental change. Yet in the Arctic, there are few empirical tests of how sustained climatic change may influence community structure. Northern Svalbard is influenced by both warm Atlantic and cold Arctic water masses, providing an opportunity to assess potential effects of long-term environmental changes by examining spatial variation in community structure. We examined benthic macroinfaunal communities and sediment pigments under Atlantic and Arctic water masses on the northern shelf and fjords of Svalbard. We report on infaunal biomass, abundance, species composition, and diversity at 10 stations spanning 79°–81°N and ranging in depth from 200 to 500?m. Benthic biomass averaged 128?g?WW?m?2 (48–253?g?WW?m?2), mean density was 3,635?ind.?m?2 (780–7,660?ind.?m?2), and species richness varied from 45 to 136?taxa?stn.?1. Abundance-based community structure clustered stations in groups related to water mass characteristics, with Atlantic and Arctic shelf stations being well distinguished from each other. Dominant taxa were different in Atlantic- and Arctic-influenced locations. Faunal biomass was highest in the Atlantic-influenced fjords, followed by Arctic fjords and Arctic shelf stations, with Atlantic shelf stations having the lowest biomass. Species richness and diversity were inversely related to biomass. Patterns in faunal biomass were strongly correlated with sedimentary pigments (R 2?=?0.74 for chl a and R 2?=?0.77 for phaeopigments), with large differences in sedimentary pigment concentration among stations. These relationships suggest that benthic fauna on the northern Svalbard shelf are food limited and dependent on predictable, albeit episodic, delivery of organic matter from the water column.  相似文献   

18.
2012 年6 月在南麂大檑山岛厚壳贻贝增殖区潮间带布设2 个断面,进行潮间带底栖生物调查。定量采集到底栖生物16 种,其中软体动物6 种,藻类、甲壳类各3 种,腔肠动物、多毛类各2 种。潮间带底栖生物平均丰度为1 592 inds/m2,平均生物量17 326.48 g/m2,以厚壳贻贝的生物量及丰度为最高。大檑山岛潮间带底栖生物的Shannon-Weiner 多样性指数(H')、Simpson 多样性指数(D)、Pielou 均匀度指数(J)和Margalef 丰富度指数(d)分别为1.25~1.53、0.46~0.54、0.49~0.75、0.92~1.25,平均值分别是1.48、0.50、0.57、1.13,多样性指数都比较低,潮间带底栖生物群落受到中度干扰。底栖生物ABC 曲线分析表明,大檑山岛潮间带底栖生物群落处于稳定状态。厚壳贻贝壳长频数分布分析表明,大檑山岛潮间带厚壳贻贝以1~2 龄为主。  相似文献   

19.
孟昭翠  徐奎栋 《生态学报》2013,33(21):6813-6824
利用Ludox-QPS方法并结合沉积环境因子的综合分析,研究了2011年4月采自长江口及东海10个站位以底栖硅藻、纤毛虫和异养小鞭毛虫为代表的微型底栖生物及小型底栖生物的组成、丰度和生物量、分布及生态特点。结果表明,底栖硅藻的丰度 (5.92 ? 104 ind/10 cm2) 和生物量 (83.29 ?g C/10 cm2) 远高于纤毛虫 (丰度为1036 ind/10 cm2,生物量为3.33 ?g C/10 cm2)、异养小鞭毛虫 (丰度为4451 ind/10 cm2,生物量为2.51 ?g C/10 cm2) 和小型底栖生物 (丰度为1947 ? 849 ind/10 cm2,生物量为49.01? 22.05 ?g C/10 cm2)。在鉴定出的11个小型底栖生物类群中,线虫占小型底栖生物总丰度的90%和总生物量的37%。底栖硅藻生物量在长江口及东海海域呈由近岸向外海逐渐降低的分布特点,而底栖纤毛虫、异养小鞭毛虫及小型底栖生物的分布则正相反。在垂直分布上,76%的硅藻和80%的线虫分布在0–2 cm沉积物表层,仅1%的硅藻和6%的线虫分布在5–8 cm分层。统计分析表明,底栖硅藻的现存量与沉积物中叶绿素a含量呈极显著的正相关,与底层水温度呈弱的正相关;该海域底栖原生动物和小型底栖生物的分布受多个因子而非单一环境因子的共同作用。对比分析表明,长江口及东海单位体积沉积物中的硅藻丰度较水体中的硅藻丰度高2个数量级,沉积物中相当部分的叶绿素a含量可能系底栖硅藻所贡献;表层8 cm沉积物中纤毛虫的丰度约是上层30 m水柱中纤毛虫丰度的30倍,生物量约是后者的40倍。尽管纤毛虫在生物量上远小于小型底栖生物,但其估算的生产力约是后者的3倍;而异养小鞭毛虫由于个体更小,其周转率可能较纤毛虫更高。长江口及东海陆架区原生动物和小型底栖生物的高现存量及生产力预示着其在该海域生态系统中的重要作用。  相似文献   

20.
A monthly survey was carried out for two years on the epifaunal community in Tolo Harbour and Tolo Channel, Hong Kong, a subtropical embayment subjected to a gradient of organic pollution. The number of animals and species, biomass and species diversity (Shannon's function H′ and evenness J), were higher at less polluted stations in the outer Harbour and Channel than at the polluted stations in the inner Harbour. The Channel community was dominated by the crab Portunus hastatoides Fabricius and the gastropod Nassarius crematus (Hinds). Along an increasing gradient of organic pollution, N. crematus was gradually replaced by the crab Charybdis vadorum (Alcock), and a community dominated by Portunus hastatoides and Charybdis vadorum was found in the polluted inner Harbour. The abundance and dominance of predatory gastropods also showed a decrease from the Channel to the inner Harbour, reflecting changes in the trophic structure of the community in relation to pollution. No significant change in the percentage of deposit-feeders was found along the pollution gradient. Summer mortality of benthos appeared to occur regularly in inner Tolo Harbour, and was attributed to summer oxygen depletion resulting from eutrophication. The benthic community was, however, soon restored to its original state by rapid winter recolonization. It is postulated that the cyclic phenomenon of summer mortality followed by winter recovery may be a common characteristic in subtropical benthic communities subjected to a high level of organic pollution.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号