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排序方式: 共有316条查询结果,搜索用时 203 毫秒
61.
Masahiro Kusumoto Dai Fukamizu Yoshitoshi Ogura Eiji Yoshida Fumiko Yamamoto Taketoshi Iwata Tadasuke Ooka Masato Akiba Tetsuya Hayashi 《Applied and environmental microbiology》2014,80(4):1394-1402
Insertion sequences (ISs) are the simplest transposable elements and are widely distributed in bacteria; however, they also play important roles in genome evolution. We recently identified a protein called IS excision enhancer (IEE) in enterohemorrhagic Escherichia coli (EHEC) O157. IEE promotes the excision of IS elements belonging to the IS3 family, such as IS629, as well as several other families. IEE-mediated IS excision generates various genomic deletions that lead to the diversification of the bacterial genome. IEE has been found in a broad range of bacterial species; however, among sequenced E. coli strains, IEE is primarily found in EHEC isolates. In this study, we investigated non-EHEC pathogenic E. coli strains isolated from domestic animals and found that IEE is distributed in specific lineages of enterotoxigenic E. coli (ETEC) strains of serotypes O139 or O149 isolated from swine. The iee gene is located within integrative elements that are similar to SpLE1 of EHEC O157. All iee-positive ETEC lineages also contained multiple copies of IS629, a preferred substrate of IEE, and their genomic locations varied significantly between strains, as observed in O157. These data suggest that IEE may have been transferred among EHEC and ETEC in swine via SpLE1 or SpLE1-like integrative elements. In addition, IS629 is actively moving in the ETEC O139 and O149 genomes and, as in EHEC O157, is promoting the diversification of these genomes in combination with IEE. 相似文献
62.
Despite detailed studies of marine sulfur-oxidizing bacteria, our knowledge concerning their counterparts in freshwater lake ecosystems is limited. Genome sequencing of the freshwater sulfur-oxidizing betaproteobacteria Sulfuricella denitrificans skB26 and Sulfuritalea hydrogenivorans sk43H have been completed. Strain skB26 possessed a circular plasmid of 86.6-kbp in addition to its chromosome, and an approximate 18-kbp region of the plasmid was occupied by an arxA-like operon, encoding a new clade of anaerobic arsenite oxidase. Multilocus sequence analysis showed that strain skB26 could not be assigned to any existing order; thus a novel order, Sulfuricellales, is proposed. The genomes of strains skB26 and sk43H were examined, focusing on the composition and the phylogeny of genes involved in the oxidation of inorganic sulfur compounds. Strains skB26 and sk43H shared a common pathway, which consisted of Sqr, SoxEF, SoxXYZAB, Dsr proteins, AprBA, Sat, and SoeABC. Comparative genomics of betaproteobacterial sulfur oxidizers showed that this pathway was also shared by the freshwater sulfur oxidizers Thiobacillus denitrificans and Sideroxydans lithotrophicus. It also revealed the presence of a conserved gene cluster, which was located immediately upstream of the betaproteobacterial dsr operon. 相似文献
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64.
Masanori Fujii Yoshinori Takano Hisaya Kojima Tamotsu Hoshino Ryouichi Tanaka Manabu Fukui 《Microbial ecology》2010,59(3):466-475
“Red snow” refers to red-colored snow, caused by bloom of cold-adapted phototrophs, so-called snow algae. The red snow found in Langhovde, Antarctica, was investigated from several viewpoints. Various sizes of rounded red cells were observed in the red snow samples under microscopy. Pigment analysis demonstrated accumulation of astaxanthin in the red snow. Community structure of microorganisms was analyzed by culture-independent methods. In the analyses of small subunit rRNA genes, several species of green algae, fungus, and various phylotypes of bacteria were detected. The detected bacteria were closely related to psychrophilic or psychrotolerant heterotrophic strains, or sequences detected from low-temperature environments. As predominant lineage of bacteria, members of the genus Hymenobacter were consistently detected from samples obtained in two different years. Nitrogen isotopic compositions analysis indicated that the red snow was significantly 15N-enriched. Based on an estimation of trophic level, it was suggested that primary nitrogen sources of the red snow were supplied from fecal pellet of seabirds including a marine top predator of Antarctica. 相似文献
65.
Yogesh Bhattarai Brianna B. Williams Eric J. Battaglioli Weston R. Whitaker Lisa Till Madhusudan Grover David R. Linden Yasutada Akiba Karunya K. Kandimalla Nicholas C. Zachos Jonathan D. Kaunitz Justin L. Sonnenburg Michael A. Fischbach Gianrico Farrugia Purna C. Kashyap 《Cell host & microbe》2018,23(6):775-785.e5
66.
In vivo effect of a TLR5 SNP (C1205T) on Salmonella enterica serovar Typhimurium infection in weaned,specific pathogen‐free Landrace piglets 下载免费PDF全文
Yoshihiro Muneta Nobuo Arai Yoko Yakabe Masahiro Eguchi Tomoyuki Shibahara Akiko Sakuma Hiroki Shinkai Hirohide Uenishi Kensuke Hirose Masato Akiba 《Microbiology and immunology》2018,62(6):380-387
67.
Special AT‐rich sequence binding protein 1 is required for maintenance of T cell receptor responsiveness and development of experimental autoimmune encephalomyelitis 下载免费PDF全文
Yasushi Akiba Taku Kuwabara Takanori Mukozu Tetuo Mikami Motonari Kondo 《Microbiology and immunology》2018,62(4):255-268
The genome organizer special AT‐rich sequence binding protein 1 (SATB1) regulates specific functions through chromatin remodeling in T helper cells. It was recently reported by our team that T cells from SATB1 conditional knockout (SATB1cKO) mice, in which the Satb1 gene is deleted from hematopoietic cells, impair phosphorylation of signaling molecules in response to T cell receptor (TCR) crosslinking. However, in vivo T cell responses upon antigen presentation in the absence of SATB1 remain unclear. In the current study, it was shown that SATB1 modulates T cell antigen responses during the induction and effector phases. Expression of SATB1 was upregulated in response to TCR stimulation, suggesting that SATB1 is important for this antigen response. The role of SATB1 in TCR responses and induced experimental autoimmune encephalomyelitis (EAE) was therefore examined using the myelin oligodendrocyte glycoprotein peptide 35‐55 (MOG35‐55) and pertussis toxin. SATB1cKO mice were found to be resistant to EAE and had defects in IL‐17‐ and IFN‐γ‐producing pathogenic T cells. Thus, SATB1 expression appears necessary for T cell function in the induction phase. To examine SATB1 function during the effector phase, a tamoxifen‐inducible SATB1 deletion system, SATB1cKO‐ER‐Cre mice, was used. Encephalitogenic T cells from MOG35‐55‐immunized SATB1cKO‐ER‐Cre mice were transferred into healthy mice. Mice that received tamoxifen before the onset of paralysis were resistant to EAE. Furthermore, no disease progression occurred in recipient mice treated with tamoxifen after the onset of EAE. Thus, SATB1 is essential for maintaining TCR responsiveness during the induction and effector phases and may provide a novel therapeutic target for T cell‐mediated autoimmune diseases. 相似文献
68.
69.
Purification and Properties of Extracellular Amylase from the Hyperthermophilic Archaeon Thermococcus profundus DT5432 总被引:2,自引:1,他引:1 下载免费PDF全文
A hyperthermophilic archaeon, Thermococcus profundus DT5432, produced extracellular thermostable amylases. One of the amylases (amylase S) was purified to homogeneity by ammonium sulfate precipitation, DEAE-Toyopearl chromatography, and gel filtration on Superdex 200HR. The molecular weight of the enzyme was estimated to be 42,000 by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The amylase exhibited maximal activity at pH 5.5 to 6.0 and was stable in the range of pH 5.9 to 9.8. The optimum temperature for the activity was 80(deg)C. Half-life of the enzyme was 3 h at 80(deg)C and 15 min at 90(deg)C. Thermostability of the enzyme was enhanced in the presence of 5 mM Ca(sup2+) or 0.5% soluble starch at temperatures above 80(deg)C. The enzyme activity was inhibited in the presence of 5 mM iodoacetic acid or 1 mM N-bromosuccinimide, suggesting that cysteine and tryptophan residues play an important role in the catalytic action. The amylase hydrolyzed soluble starch, amylose, amylopectin, and glycogen to produce maltose and maltotriose of (alpha)-configuration as the main products. Smaller amounts of larger maltooligosaccharides were also produced with a trace amount of glucose. Pullulan; (alpha)-, (beta)-, and (gamma)-cyclodextrins; maltose; and maltotriose were not hydrolyzed. 相似文献
70.
Transcriptional and morphological changes in the transition from mycetophagous to phytophagous phase in the plant‐parasitic nematode Bursaphelenchus xylophilus 下载免费PDF全文