全文获取类型
收费全文 | 13345篇 |
免费 | 1057篇 |
国内免费 | 2篇 |
出版年
2023年 | 69篇 |
2022年 | 156篇 |
2021年 | 270篇 |
2020年 | 160篇 |
2019年 | 192篇 |
2018年 | 259篇 |
2017年 | 253篇 |
2016年 | 411篇 |
2015年 | 666篇 |
2014年 | 765篇 |
2013年 | 922篇 |
2012年 | 1253篇 |
2011年 | 1159篇 |
2010年 | 701篇 |
2009年 | 620篇 |
2008年 | 892篇 |
2007年 | 929篇 |
2006年 | 778篇 |
2005年 | 759篇 |
2004年 | 669篇 |
2003年 | 639篇 |
2002年 | 629篇 |
2001年 | 108篇 |
2000年 | 78篇 |
1999年 | 103篇 |
1998年 | 144篇 |
1997年 | 88篇 |
1996年 | 75篇 |
1995年 | 70篇 |
1994年 | 71篇 |
1993年 | 71篇 |
1992年 | 51篇 |
1991年 | 47篇 |
1990年 | 42篇 |
1989年 | 26篇 |
1988年 | 24篇 |
1987年 | 22篇 |
1986年 | 23篇 |
1985年 | 15篇 |
1984年 | 22篇 |
1983年 | 19篇 |
1982年 | 8篇 |
1981年 | 17篇 |
1980年 | 14篇 |
1979年 | 10篇 |
1978年 | 11篇 |
1975年 | 8篇 |
1971年 | 11篇 |
1969年 | 8篇 |
1966年 | 8篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
An unusual propionigenic bacterium was isolated from the intestinal tract of the soil-feeding termite Thoracotermes macrothorax. Strain TmPN3 is a motile, long rod that stains gram-positive, but reacts gram-negative in the KOH test. It forms terminal
endospores and ferments lactate, glucose, lactose, fructose, and pyruvate to propionate and acetate via the methyl-malonyl-CoA
pathway. Propionate and acetate are formed at a ratio of 2:1, typical of most propionigenic bacteria. Under a H2/CO2 atmosphere, the fermentation product pattern of glucose, fructose, and pyruvate shifts towards propionate formation at the
expense of acetate. Cell suspensions reduce oxygen with lactate, glucose, glycerol, or hydrogen as electron donor. In the
presence of oxygen, the product pattern of lactate fermentation shifts from propionate to acetate production. 16S rRNA gene
sequence analysis showed that strain TmPN3 is a firmicute that clusters among the Acidaminococcaceae, a subgroup of the Clostridiales
comprising obligately anaerobic, often endospore-forming bacteria that possess an outer membrane. Based on phenotypic differences
and less than 92% sequence similarity to the 16S rRNA gene sequence of its closest relative, the termite hindgut isolate Acetonema longum, strain TmPN3T is proposed as the type species of a new genus, Sporotalea
propionica gen. nov. sp. nov. (DSM 13327T, ATCC BAA-626T). 相似文献
993.
RNAmmer: consistent and rapid annotation of ribosomal RNA genes 总被引:7,自引:0,他引:7
Lagesen K Hallin P Rødland EA Staerfeldt HH Rognes T Ussery DW 《Nucleic acids research》2007,35(9):3100-3108
The publication of a complete genome sequence is usually accompanied by annotations of its genes. In contrast to protein coding genes, genes for ribosomal RNA (rRNA) are often poorly or inconsistently annotated. This makes comparative studies based on rRNA genes difficult. We have therefore created computational predictors for the major rRNA species from all kingdoms of life and compiled them into a program called RNAmmer. The program uses hidden Markov models trained on data from the 5S ribosomal RNA database and the European ribosomal RNA database project. A pre-screening step makes the method fast with little loss of sensitivity, enabling the analysis of a complete bacterial genome in less than a minute. Results from running RNAmmer on a large set of genomes indicate that the location of rRNAs can be predicted with a very high level of accuracy. Novel, unannotated rRNAs are also predicted in many genomes. The software as well as the genome analysis results are available at the CBS web server. 相似文献
994.
995.
996.
997.
998.
The Termite Group I Phylum Is Highly Diverse and Widespread in the Environment 总被引:1,自引:0,他引:1 下载免费PDF全文
The bacterial candidate phylum Termite Group I (TG-1) presently consists mostly of “Endomicrobia,” which are endosymbionts of flagellate protists occurring exclusively in the hindguts of termites and wood-feeding cockroaches. Here, we show that public databases contain many, mostly undocumented 16S rRNA gene sequences from other habitats that are affiliated with the TG-1 phylum but are only distantly related to “Endomicrobia.” Phylogenetic analysis of the expanded data set revealed several diverse and deeply branching lineages comprising clones from many different habitats. In addition, we designed specific primers to explore the diversity and environmental distribution of bacteria in the TG-1 phylum. 相似文献
999.
Varvara Mouchtouri Emmanuel Velonakis Andreas Tsakalof Christina Kapoula Georgia Goutziana Alkiviadis Vatopoulos Jenny Kremastinou Christos Hadjichristodoulou 《Applied microbiology》2007,73(5):1489-1492
The Legionella colonization frequency at 385 Greek hotel hot and cold water distribution systems was 20.8%. Legionella contamination was associated with the presence of an oil heater (odds ratio [OR] = 2.04, 95% confidence interval [CI] = 1.12 to 3.70), with the sample temperature (OR = 0.26, 95% CI = 0.1 to 0.5), with seasonal operation (OR = 3.23, 95% CI = 1.52 to 6.87), and with the presence of an independent disinfection system (OR = 0.30, 95% CI = 0.15 to 0.62). The same water temperatures, free-chlorine levels, and pHs differently affect the survival of various Legionella spp. 相似文献
1000.
Modelling radiation fluxes in simple and complex environments—application of the RayMan model 总被引:3,自引:0,他引:3
The most important meteorological parameter affecting the human energy balance during sunny weather conditions is the mean
radiant temperature Tmrt. It considers the uniform temperature of a surrounding surface giving off blackbody radiation, which results in the same
energy gain of a human body given the prevailing radiation fluxes. This energy gain usually varies considerably in open space
conditions. In this paper, the model ‘RayMan’, used for the calculation of short- and long-wave radiation fluxes on the human
body, is presented. The model, which takes complex urban structures into account, is suitable for several applications in
urban areas such as urban planning and street design. The final output of the model is, however, the calculated Tmrt, which is required in the human energy balance model, and thus also for the assessment of the urban bioclimate, with the
use of thermal indices such as predicted mean vote (PMV), physiologically equivalent temperature (PET) and standard effective
temperature (SET*). The model has been developed based on the German VDI-Guidelines 3789, Part II (environmental meteorology,
interactions between atmosphere and surfaces; calculation of short- and long-wave radiation) and VDI-3787 (environmental meteorology,
methods for the human-biometeorological evaluation of climate and air quality for urban and regional planning. Part I: climate).
The validation of the results of the RayMan model agrees with similar results obtained from experimental studies. 相似文献