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11.
Cafaro MJ Poulsen M Little AE Price SL Gerardo NM Wong B Stuart AE Larget B Abbot P Currie CR 《Proceedings. Biological sciences / The Royal Society》2011,278(1713):1814-1822
Fungus-growing ants (tribe Attini) engage in a mutualism with a fungus that serves as the ants' primary food source, but successful fungus cultivation is threatened by microfungal parasites (genus Escovopsis). Actinobacteria (genus Pseudonocardia) associate with most of the phylogenetic diversity of fungus-growing ants; are typically maintained on the cuticle of workers; and infection experiments, bioassay challenges and chemical analyses support a role of Pseudonocardia in defence against Escovopsis through antibiotic production. Here we generate a two-gene phylogeny for Pseudonocardia associated with 124 fungus-growing ant colonies, evaluate patterns of ant-Pseudonocardia specificity and test Pseudonocardia antibiotic activity towards Escovopsis. We show that Pseudonocardia associated with fungus-growing ants are not monophyletic: the ants have acquired free-living strains over the evolutionary history of the association. Nevertheless, our analysis reveals a significant pattern of specificity between clades of Pseudonocardia and groups of related fungus-growing ants. Furthermore, antibiotic assays suggest that despite Escovopsis being generally susceptible to inhibition by diverse Actinobacteria, the ant-derived Pseudonocardia inhibit Escovopsis more strongly than they inhibit other fungi, and are better at inhibiting this pathogen than most environmental Pseudonocardia strains tested. Our findings support a model that many fungus-growing ants maintain specialized Pseudonocardia symbionts that help with garden defence. 相似文献
12.
Ceribelli A Yao B Dominguez-Gutierrez PR Nahid MA Satoh M Chan EK 《Arthritis research & therapy》2011,13(4):229
MicroRNAs (miRNAs) are endogenous, non-coding, single-stranded RNAs about 21 nucleotides in length. miRNAs have been shown
to regulate gene expression and thus influence a wide range of physiological and pathological processes. Moreover, they are
detected in a variety of sources, including tissues, serum, and other body fluids, such as saliva. The role of miRNAs is evident
in various malignant and nonmalignant diseases, and there is accumulating evidence also for an important role of miRNAs in
systemic rheumatic diseases. Abnormal expression of miRNAs has been reported in autoimmune diseases, mainly in systemic lupus
erythematosus and rheumatoid arthritis. miRNAs can be aberrantly expressed even in the different stages of disease progression,
allowing miRNAs to be important biomarkers, to help understand the pathogenesis of the disease, and to monitor disease activity
and effects of treatment. Different groups have demonstrated a link between miRNA expression and disease activity, as in the
case of renal flares in lupus patients. Moreover, miRNAs are emerging as potential targets for new therapeutic strategies
of autoimmune disorders. Taken together, recent data demonstrate that miRNAs can influence mechanisms involved in the pathogenesis,
relapse, and specific organ involvement of autoimmune diseases. The ultimate goal is the identification of a miRNA target
or targets that could be manipulated through specific therapies, aiming at activation or inhibition of specific miRNAs responsible
for the development of disease. 相似文献
13.
Satoh M Krzyszczak ME Li Y Ceribelli A Ross SJ Chan EK Segal MS Bubb MR Sobel ES Reeves WH 《Arthritis research & therapy》2011,13(3):R73
Introduction
The presence of anti-topoisomerase I (topo I) antibodies is a classic scleroderma (SSc) marker presumably associated with a unique clinical subset. Here the clinical association of anti-topo I was reevaluated in unselected patients seen in a rheumatology clinic setting. 相似文献14.
Jennifer L Bowen Bess B Ward Hilary G Morrison John E Hobbie Ivan Valiela Linda A Deegan Mitchell L Sogin 《The ISME journal》2011,5(9):1540-1548
Functional redundancy in bacterial communities is expected to allow microbial assemblages to survive perturbation by allowing continuity in function despite compositional changes in communities. Recent evidence suggests, however, that microbial communities change both composition and function as a result of disturbance. We present evidence for a third response: resistance. We examined microbial community response to perturbation caused by nutrient enrichment in salt marsh sediments using deep pyrosequencing of 16S rRNA and functional gene microarrays targeting the nirS gene. Composition of the microbial community, as demonstrated by both genes, was unaffected by significant variations in external nutrient supply in our sampling locations, despite demonstrable and diverse nutrient-induced changes in many aspects of marsh ecology. The lack of response to external forcing demonstrates a remarkable uncoupling between microbial composition and ecosystem-level biogeochemical processes and suggests that sediment microbial communities are able to resist some forms of perturbation. 相似文献
15.
16.
HIV-1 within the CNS produces a neuroAIDS syndrome and may act as a reservoir for reinfection of the peripheral tissues. Study of how HIV-1 crosses the blood-brain barrier (BBB) has been hampered by the lack of nonprimate animal models. However, BBB transport of HIV-1 does not involve any of the known steps conferring species specificity, including binding to CD4 receptors. In vivo and in vitro studies show that HIV-1 and its glycoprotein coat, gp120, are taken up and transported across the BBB of the mouse. Here, we compared the ability of gp120 and HIV-1 to be taken up by isolated brain microvessels (IBM) freshly isolated from mice, from post-mortem human brain, and from mice that had been treated in a manner analogous to the human material (mouse post-mortem). Freshly isolated mouse IBM took up more gp120 and HIV-1 than the human or mouse post-mortem cells. We found no difference between the ability of mouse post-mortem and human IBM to take up either gp120 or HIV-1. Wheatgerm agglutinin has been previously shown to stimulate gp120 and HIV-1 uptake by the BBB; here, it stimulated the uptake of gp120 and of HIV-1 by both mouse post-mortem and human IBM, although stimulated uptake was greatest for fresh mouse IBM. These results show that the mouse can be used to study the initial phases of HIV-1 uptake by the BBB. 相似文献
17.
Dominant Microbial Populations in Limestone-Corroding Stream Biofilms, Frasassi Cave System, Italy 总被引:3,自引:2,他引:1 下载免费PDF全文
Jennifer L. Macalady Ezra H. Lyon Bess Koffman Lindsey K. Albertson Katja Meyer Sandro Galdenzi Sandro Mariani 《Applied microbiology》2006,72(8):5596-5609
Waters from an extensive sulfide-rich aquifer emerge in the Frasassi cave system, where they mix with oxygen-rich percolating water and cave air over a large surface area. The actively forming cave complex hosts a microbial community, including conspicuous white biofilms coating surfaces in cave streams, that is isolated from surface sources of C and N. Two distinct biofilm morphologies were observed in the streams over a 4-year period. Bacterial 16S rDNA libraries were constructed from samples of each biofilm type collected from Grotta Sulfurea in 2002. β-, γ-, δ-, and -proteobacteria in sulfur-cycling clades accounted for ≥75% of clones in both biofilms. Sulfate-reducing and sulfur-disproportionating δ-proteobacterial sequences in the clone libraries were abundant and diverse (34% of phylotypes). Biofilm samples of both types were later collected at the same location and at an additional sample site in Ramo Sulfureo and examined, using fluorescence in situ hybridization (FISH). The biomass of all six stream biofilms was dominated by filamentous γ-proteobacteria with Beggiatoa-like and/or Thiothrix-like cells containing abundant sulfur inclusions. The biomass of -proteobacteria detected using FISH was consistently small, ranging from 0 to less than 15% of the total biomass. Our results suggest that S cycling within the stream biofilms is an important feature of the cave biogeochemistry. Such cycling represents positive biological feedback to sulfuric acid speleogenesis and related processes that create subsurface porosity in carbonate rocks. 相似文献
18.
19.
Mitochondria lack the ability to repair certain helix-distorting lesions that are induced at high levels in mitochondrial DNA (mtDNA) by important environmental genotoxins and endogenous metabolites. These lesions are irreparable and persistent in the short term, but their long-term fate is unknown. We report that removal of such mtDNA damage is detectable by 48 h in Caenorhabditis elegans, and requires mitochondrial fusion, fission and autophagy, providing genetic evidence for a novel mtDNA damage removal pathway. Furthermore, mutations in genes involved in these processes as well as pharmacological inhibition of autophagy exacerbated mtDNA damage-mediated larval arrest, illustrating the in vivo relevance of removal of persistent mtDNA damage. Mutations in genes in these pathways exist in the human population, demonstrating the potential for important gene-environment interactions affecting mitochondrial health after genotoxin exposure. 相似文献
20.
JINDŘIŠKA BOJKOVÁ KLÁRA KOMPRDOVÁ TOMÁŠ SOLDÁN SVĚTLANA ZAHRÁDKOVÁ 《Freshwater Biology》2012,57(12):2550-2567
1. Rapid expansion and intensification of anthropogenic activities in the 20th century has caused profound changes in freshwater assemblages. Unfortunately, knowledge of the extent and causes of species loss (SL) is limited due to the lack of reliable historical data. An unusual data set allows us to compare changes in the most sensitive of aquatic insect orders, the Plecoptera, at some 170 locations in the Czech Republic between two time periods, 1955–1960 and 2006–2010. Historical data (1890–1911) on assemblages of six lowland rivers allow us to infer even earlier changes. 2. Regional stonefly diversity decreased in the first half of the 20th century. Streams at lower altitudes lost a substantial number of species, which were never recovered. In the second half of the century, large‐scale anthropogenic pressure caused SL in all habitats, leading to a dissimilarity of contemporary and previous assemblages. The greatest changes were found at sites affected by organic pollution and a mixture of organic pollution and channelisation or impoundment. Colonisation of new habitats was observed in only three of the 80 species evaluated. 3. Species of moderate habitat specialisation and tolerance to organic pollution were most likely to be lost. Those with narrow specialisations in protected habitats were present in both historical and contemporary collections. 4. Contemporary assemblages are the consequence of more than a 100 years of anthropogenic impacts. In particular, streams at lower altitude and draining intensively exploited landscapes host a mere fragment of the original species complement. Most stonefly species are less frequently present than before, although their assemblages remain almost intact in near‐natural mountain streams. Our analyses demonstrate dramatic restriction of species ranges and, in some cases, apparent changes in altitudinal preference throughout the area. 相似文献