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Bacterial diversity in deep-sea sediments from different depths   总被引:38,自引:0,他引:38  
Seven sediment samples have been examined, taken from different depths of the deep-sea in the range of 1159m to 6482m. A total of 75 different 16S rDNA sequences (149 clones) analyzed clustered into the Proteobacteria, Gram-positive bacteria, Cytophaga, Planctomyces, and Actinomycetes and many sequences were from microorganisms that showed no phylogenetic affiliation with known bacteria. Clones identical to 16S rDNA sequences of members of the genus Pseudomonas were observed in all of the sediments examined. The second group of common sequences cloned from six sediment samples was related to the 16S rDNA sequence of a chemoautotrophic bacterium, the Solemya velum symbiont. Five 16S rDNA sequences from three sediments were related to those of the Alvinella pompejana epibiont which is a member of the -Proteobacteria. Only one sequence was obtained that was closely related to the 16S rDNA of the barophilic bacterium, Shewanella benthica, which might be a minor population in the deeper sediments. -Proteobacteria-related sequences were cloned from sediments obtained from sites near man-made garbage deposits and a Calyptogena community. These environments obviously would be richer in nutrients than other sites, and might be expected to show more types of bacteria than other deep-sea sediments. A large number of cloned sequences in this study showed very low identity to known sequences. These sequences may represent communities of as-yet-uncultivated microorganisms in the sediments.  相似文献
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采用普通牛肉汁培养基和 10倍稀释的普通牛肉汁培养基 (以下简称稀释培养基 )研究太湖沉积物中细菌多样性 ,发现在稀释培养基上生长的细菌数量普遍是在普通牛肉汁琼脂培养基上生长的细菌数量的 3~ 5倍。分离得到纯培养物的 16SrDNA部分序列 (5′端约 5 0 0bp)分析表明 ,不同培养基上生长的优势细菌类群存在差别 :普通培养基生长的细菌主要为γ_Proteobacteria(35. 1% ) ,其次为Actinobacteria(2 4 5 % )和Firmicutes(2 2 . 3% )等类群 ,其中大部分细菌与假单胞菌属 (Pseudomoas)、芽孢杆菌属 (Bacillus)和节杆菌属 (Archrobacter)细菌的系统关系密切 ;稀释培养基生长的细菌则主要为Actinobacteria(2 7. 1% )、Firmicutes(2 5 . 7% )、α_Proteobacteria(2 1. 4 % )和γ_Proteobacteria(15. 7% )等类群 ,与芽孢杆菌属 (Bacillus) (2 5. 7% )发育系统关系密切的细菌为优势属。研究结果表明同时采用两种培养基有助于从太湖沉积物中分离到更多种微生物。  相似文献
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太湖地区典型菜地土壤微生物16S rDNA的PCR-RFLP分析   总被引:22,自引:1,他引:21       下载免费PDF全文
土壤微生物多样性是土壤生态功能的基础,但长期以来缺乏对高强度土地利用条件下的土壤微生物多样性的认识.作者采用间接法提取了江苏省太湖地区典型菜地土壤微生物的总DNA,以细菌的通用引物27F和1492R扩增16S rDNA片段,将扩增产物与T-载体酶连,转化大肠杆菌,建立土壤微生物16S rDNA克隆文库.PCR扩增基因文库中插入的16S rDNA外源片段,用两种限制性内切酶Hha I和Rsa I分别酶切,获得该土壤173个克隆的酶切指纹图谱.结果表明,Hha I和Rsa I联合酶切产生了63个基因分型,文库的覆盖度达76.30%,单一酶切产生的基因分型少,但文库的覆盖度高;克隆文库中存在两种优势类群,分别占总克隆的16%和12%.16S rDNA测序结果表明,太湖地区菜地土壤细菌在分类方面主要属于α-和γ-变形杆菌亚门.以上结果为进一步研究太湖地区菜地土壤微生物生态功能提供了基础资料.  相似文献
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The microbial community of a deep (to 234 m below the sea floor) sediment gas hydrate deposit (Cascadia Margin Ocean Drilling Program Site 889/890, Leg 146) was analysed for the first time by molecular genetic techniques. Both bacterial and methanogen diversity were determined by phylogenetic analysis of ribosomal DNA sequences. High molecular mass DNA, indicative of active bacteria, was present in all of the samples. Ribosomal RNA genes were amplified from extracted DNA extracted from sediment using bacteria, and methanogen specific PCR primers, the latter designed in this study. Phylogenetic analysis of approximately 400 bacterial clones demonstrated that 96% were members of the Proteobacteria. These clones were affiliated with the alpha, beta and gamma subdivisions, with Caulobacter (Zymomonas group), Ralstonia and Pseudomonas phylotypes predominating. The methanogen clones were of low diversity and clustered in three sub-groups. Two of these sub-groups (contained 96% of the 400 clones) were closely related to Methanosarcina mazeii, while the third sub-group clustered in the Methanobacteriales. This analysis of a deep sediment gas hydrate environment shows a bacteria and methanogen community of limited diversity and confirms that the gas hydrate zone is biogeochemically active. These results are consistent with the presence of bacterial populations capable of methanogenesis throughout the core, and suggest that the methane hydrate at this site is at least partially biogenic in origin.  相似文献
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Using different techniques of molecular biology we investigated the bacterial diversity of the chemocline of the meromictic Lake Cadagno. Cloning of a total community 16S rDNA PCR product and subsequent screening with a combination of amplified ribosomal DNA restriction analysis and temporal temperature gradient gel electrophoresis (TTGE) analysis revealed that 30 of 47 randomly selected clones were unique. Partial sequencing and comparative analysis indicated a high bacterial diversity dominated by the gamma-Proteobacteria (33.3%). Most of these rDNA clone sequences were not closely related to any 16S rDNA sequence in the database. In a second approach, the TTGE pattern from an environmental sample was compared with the migration of the cloned 16S rDNA fragments. Four clone types were identified on the environmental pattern by excising and sequencing comigrating bands, three of which were well represented in the library: two Chromatiaceae species and one sequence affiliated with the Desulfobulbus assemblage. Using the fluorescent in situ hybridization technique we essentially confirmed the results of the cloning experiments and the TTGE analysis.  相似文献
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