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931.
An Amino Acid Substitution at Position 740 in σ70 of Ralstonia solanacearum Strain OE1-1 Affects Its In Planta Growth
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Ayami Kanda Kazuhiro Tsuneishi Ai Mori Kouhei Ohnishi Akinori Kiba Yasufumi Hikichi 《Applied microbiology》2008,74(18):5841-5844
Growth of Ralstonia solanacearum strain OE1-1 in roots after invasion is required for virulence. An Arg740Cys substitution in σ70 of OE1-1 resulted in loss of in planta growth and virulence. The negative dominance of mutant σ70 over the wild-type protein suggested that the amino acid substitution may affect the in planta growth of OE1-1, leading to a lack of virulence. 相似文献
932.
Kuga T Hoshino M Nakayama Y Kasahara K Ikeda K Obata Y Takahashi A Higashiyama Y Fukumoto Y Yamaguchi N 《Experimental cell research》2008,314(10):2040-2054
Protein-tyrosine phosphorylation is regulated by protein-tyrosine kinases and protein-tyrosine phosphatases (PTPs). Src-family tyrosine kinases (SFKs) participate in the regulation of the actin cytoskeleton. Actin filaments can be accumulated in a cap at the dorsal cell surface, which is called the cortical actin cap. Here, we show that SFKs play an important role in formation of the cortical actin cap. HeLa cells normally exhibit the cortical actin cap, one of the major sites of tyrosine phosphorylation. The cortical actin cap is disrupted by SFK inhibitors or overexpression of the Lyn SH3 domain. Csk-knockout cells form the cortical actin cap when the level of tyrosine phosphorylation is increased by Na3VO4, a PTP inhibitor, and the formation of the cortical actin cap is inhibited by SFK inactivation with re-introduction of Csk. SYF cells lacking SFKs minimally exhibit the cortical actin cap even in the presence of Na3VO4, and transfection with Lyn restores the cortical actin cap in the presence of Na3VO4. Disruption of the cortical actin cap by dominant-negative Cdc42 causes loss of tyrosine phosphorylation at the cell top. These results suggest that SFK(s) is involved in formation of the cortical actin cap, which may serve as a platform of tyrosine phosphorylation signaling. 相似文献
933.
Kochetov AV Ahmad S Ivanisenko V Volkova OA Kolchanov NA Sarai A 《FEBS letters》2008,582(9):1293-1297
It is known that eukaryotic ribosomes are able to translate small ORFs and reinitiate translation at downstream start codons. However, this mechanism is widely considered to be inefficient and it is not commonly taken into account. We compiled a sample of human mRNAs containing small upstream ORFs overlapping with annotated protein coding sequences. Statistical analysis supported the hypothesis on reinitiation of translation at downstream AUG codons and functional significance of potential alternative ORFs. It may be assumed that some 5'UTR-located upstream ORFs can deliver ribosomes to alternative translation starts, and they should be taken into consideration in the prediction of human mRNA coding potential. 相似文献
934.
Systematic identification and sequence analysis of the genomic islands of the enteropathogenic Escherichia coli strain B171-8 by the combined use of whole-genome PCR scanning and fosmid mapping
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Ogura Y Abe H Katsura K Kurokawa K Asadulghani M Iguchi A Ooka T Nakayama K Yamashita A Hattori M Tobe T Hayashi T 《Journal of bacteriology》2008,190(21):6948-6960
Enteropathogenic Escherichia coli (EPEC) and enterohemorrhagic E. coli (EHEC) are diarrheagenic pathogens that colonize the intestinal tract through the formation of attaching and effacing lesions, induced by effectors translocated via a type III secretion system (T3SS) encoded on the locus of enterocyte effacement (LEE). In EHEC O157, numerous virulence factors, including around 40 T3SS effectors, have been identified. Most of them are encoded on genomic islands (GEIs) such as prophages and integrative elements. For EPEC, however, no systematic search of GEIs and virulence-related genes carried therein has been done, and only a limited number of virulence factors have been identified so far. In this study, we performed a systemic and genome-wide survey of the GEIs in strain B171-8, one of the prototype strains of EPEC, by the combined use of whole-genome PCR scanning and fosmid mapping and identified 22 large GEIs, including nine lambda-like prophages, three P2-like prophages, the LEE, and three additional integrative elements. On these prophages and integrative elements, we found genes for a set of T3SS proteins, a total of 33 T3SS effectors or effector homologues, and 12 other virulence factors which include five nonfimbrial adhesins. Most of the T3SS effector families identified are also present in EHEC O157, but B171-8 possesses a significantly smaller number of effectors. Not only the presence or absence of Shiga toxin genes but also the difference in the T3SS effector repertoire should be considered in analyzing the pathogenicity of EPEC and EHEC strains. 相似文献
935.
Osakada F Ikeda H Mandai M Wataya T Watanabe K Yoshimura N Akaike A Akaike A Sasai Y Takahashi M 《Nature biotechnology》2008,26(2):215-224
We previously reported the differentiation of mouse embryonic stem (ES) cells into retinal progenitors. However, these progenitors rarely differentiate into photoreceptors unless they are cultured with embryonic retinal tissues. Here we show the in vitro generation of putative rod and cone photoreceptors from mouse, monkey and human ES cells by stepwise treatments under defined culture conditions, in the absence of retinal tissues. With mouse ES cells, Crx+ photoreceptor precursors were induced from Rx+ retinal progenitors by treatment with a Notch signal inhibitor. Further application of fibroblast growth factors, Shh, taurine and retinoic acid yielded a greater number of rhodopsin+ rod photoreceptors, in addition to default cone production. With monkey and human ES cells, feeder- and serum-free suspension culture combined with Wnt and Nodal inhibitors induced differentiation of Rx+ or Mitf+ retinal progenitors, which produced retinal pigment epithelial cells. Subsequent treatment with retinoic acid and taurine induced photoreceptor differentiation. These findings may facilitate the development of human ES cell-based transplantation therapies for retinal diseases. 相似文献
936.
937.
Steroid hormones are essential for the normal function of most organ systems in vertebrates. Reproductive activities in females and males, such as the differentiation, growth and maintenance of the reproductive system, require signaling by sex steroid hormones. Although extensively studied in mammals and a few fish and bird species, the evolution and molecular mechanisms associated with the nuclear steroid hormone receptors are still poorly understood in amphibians and reptiles. Given our interest in environmental signaling of sex determination as well as a major interest in environmental contaminants that can mimic steroid hormone signaling, we have established an approach to study the molecular function (ligand binding and trans-activation) of steroid hormone receptors cloned from reptiles. This approach involves molecular cloning and sequencing of steroid hormone receptors, phylogenic analysis and in vitro trans-activation assays using endogenous or exogenous ligands. Comparing the in vitro trans-activation induced by different ligands with receptors cloned from different species would develop additional functional relationships (classification) among steroid hormone receptors. This approach can provide insight into understanding why each species could have different responses to exogenous ligands. Further, we have developed a novel and less invasive approach to obtaining mRNA for molecular cloning and sequencing of steroid hormone receptors in reptiles and other non-mammalian species, using blood cells as a source of genetic material. For example, white blood cells (WBCs) and red blood cells (RBCs) of the American alligator both express steroid hormone receptors and have adequate amounts of mRNA for molecular cloning. This approach would allow us to analyze components of endocrine function of steroid hormones without sacrificing animals. Especially in endangered species, this approach could provide an understanding of endocrine functions, elucidate the phylogenic relationships of various receptors in vitro, such as the steroid hormone receptors, and determine possible effects of environmental contaminants in a minimally invasive manner. 相似文献
938.
Structures and functions of the extrinsic proteins of photosystem II from different species 总被引:1,自引:0,他引:1
This minireview presents a summary of information available on the variety and binding properties of extrinsic proteins that form the oxygen-evolving complex of photosystem II (PSII) of cyanobacteria, red alga, diatom, green alga, euglena, and higher plants. In addition, the structure and function of extrinsic PsbO, PsbV, and PsbU proteins are summarized based on the crystal structure of thermophilic cyanobacterial PSII together with biochemical and genetic studies from various organisms. 相似文献
939.
The cause of influenza to the brain was investigated using the A/NWS/33 influenza virus infected BALB/c mouse model. NOS-2
mRNA levels in the infected mouse brain was greater than in control mice in all brain regions examined, particularly in the
olfactory bulb and hippocampus by 1 day p.i. On the contrary, no differences in NOS-1 or NOS-3 mRNA levels were found between
infected and control mice. There was also a marked increase in the levels of metabolites of nitric oxide in the olfactory
bulb and hippocampus. Immunohistochemistry showed positive staining for anti-NOS-2 primarily in the hippocampus of infected
mice. Further, anti-NOS-2 and GFAP staining was mostly found around capillary blood vessels of the hippocampus starting early
in the course of the disease. These results indicate that the NWS enhances the activation of astrocytes and NOS-2 expression
which in turn enhances NO production and the expansion of capillary blood vessels. 相似文献
940.
Habitat fragmentation seriously damages local biodiversity of widespread organisms, or so-called common species, in agricultural
habitats. We hypothesized that specialists adaptive to local particular conditions makes a population of generalists vulnerable
to habitat fragmentation. To evaluate the extinction-proneness of common rural species, we determined the extent of phenotypic
divergence using paddy fish, medaka, Oryzias latipes. Despite its wide geographical range, a rapid population decline threatens its persistence, and remnants persist in fragmented
patches. We studied niche profiling of populations from different habitats for a factor that possibly lies behind the species
being abundant within particular areas. Measurements of behavioral and morphological characteristics provided comparable variables
between populations. Principal component analysis summarized these variables into compounded elements relevant to foraging
and predator avoidance. Detection of association between behavioral and morphological traits showed a limited number of phenotypes
specific to a local habitat, through which individuals adapted to specific narrow niches. Medaka maintains its status by accumulating
a variety of local specialists. Because of the limited-dispersal ability, specialized individuals are vulnerable to isolation
in less suitable patches that are caused by the destruction of the habitat-network. From a conservation point of view, the
results suggest that preservation of habitats that also serve as corridors is recommended for enhancing the richness of common
species that are composed of adaptively diversified phenotypes. 相似文献