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Johnson DA Sharma RK Allan K Ray R Johnson LR 《Cell motility and the cytoskeleton》2004,58(4):269-280
In order to form and maintain a protective barrier for photoreceptors, the retinal pigment epithelium relies on integrin signaling and related pathways to form adhesion complexes, undergo cell spreading, and establish a confluent cellular monolayer. Polyamines are multifunctional polycations that are essential for cell attachment and spreading, although their exact mechanisms of action are as yet unclear. We report new immunocytochemical evidence suggesting that in the cells of retinal pigment epithelium and also the intestinal epithelium, polyamines are present in a population of intracellular vesicles that appear transiently during initial stages of cell spreading. In newly attached cells with minimal spreading, the vesicles are seen near the nucleus, whereas in more highly spread cells, the vesicles are localized to the plasma membrane, near, but not precisely co-localized with an enzyme marker for adhesion complexes, focal adhesion kinase. We also observe pronounced nuclear staining in newly attached cells that have not spread, whereas this staining is decreased in cells that have spread. Nuclear staining has been previously reported in other cell types and has been attributed to DNA binding of polyamines, which is known to stabilize chromatin structure. We hypothesize that the appearance of polyamine vesicles near focal adhesions of cells undergoing attachment and spreading may reflect the mechanism by which polyamine pools are targeted to appropriate interaction sites necessary for the assembly of adhesion complexes. Alternatively, the vesicles could represent the mechanism by which polyamines are removed from the nucleus and possibly released from the cell. 相似文献
975.
Srimoyee Ghosh Allan J Yates Michael C Fruhwald Jeffrey C Miecznikowski Christoph Plass Dominic J Smiraglia 《Epigenetics》2010,5(6):527-538
Although most CpG islands are generally thought to remain unmethylated in all adult somatic tissues, recent genome-wide approaches have found that some CpG islands have distinct methylation patterns in various tissues, with most differences being seen between germ cells and somatic tissues. Few studies have addressed this among human somatic tissues and fewer still have studied the same sets of tissues from multiple individuals. In the current study, we used Restriction Landmark Genomic Scanning to study tissue specific methylation patterns in a set of 12 human tissues collected from multiple individuals. We identified 34 differentially methylated CpG islands among these tissues, many of which showed consistent patterns in multiple individuals. Of particular interest were striking differences in CpG island methylation, not only among brain regions, but also between white and grey matter of the same region. These findings were confirmed for selected loci by quantitative bisulfite sequencing. Cluster analysis of the RLGS data indicated that several tissues clustered together, but the strongest clustering was in brain. Tissues from different brain regions clustered together, and, as a group, brain tissues were distinct from either mesoderm or endoderm derived tissues which demonstrated limited clustering. These data demonstrate consistent tissue specific methylation for certain CpG islands, with clear differences between white and grey matter of the brain. Furthermore, there was an overall pattern of tissue specifically methylated CpG islands that distinguished neural tissues from non-neural.Key words: Tissue specific methylation, CpG island methylation, neural, brain tissue, grey matter, white matter 相似文献
976.
Antagonism against the grey mould pathogen Botrytis cinerea by Pseudomonas antimicrobica was demonstrated in vitro and in vivo. Cell-free filtrates showed activity against B. cinerea growing on Potato Dextrose Agar (PDA) in a media-dependent manner with the most distinct antagonism being produced in Czapek Dox Broth (CDB). Cell-free filtrates of CDB-grown cultures also significantly reduced conidial germination of B. cinerea. An assays based on the inhibition of conidial germination was compared with two assays measuring the antagonism of mycelial growth on PDA. The conidial germination bioassay was more sensitive in the detection of this antifungal activity than the Petri dish bioassay while a bioassay using Microdetection plates did not detect antagonism due to the small loading capacity of the latter. The conidial germination bioassay was modified for detection of antibiosis on the surface of strawberry leaves. Significant reductions in percentage conidial germination were recorded on the surface of leaves of both micropropagated and glasshouse grown strawberry plants when the antifungal compounds of Ps. antimicrobica were applied to the leaf tissue with the conidia. In addition, antifungal compounds were also detectable when conidia were applied to leaf tissue which had previously been sprayed with cells of Ps. antimicrobica. These tests indicate that Ps. antimicrobica would be a suitable biocontrol agent for the control of B. cinerea. 相似文献
977.
Estate Sokhadze Joshua Baruth Allan Tasman Lonnie Sears Grace Mathai Ayman El-Baz Manuel F. Casanova 《Applied psychophysiology and biofeedback》2009,34(1):37-51
To better understand visual processing abnormalities in autism we studied the attention orienting related frontal event potentials
(ERP) and the sustained attention related centro-parietal ERPs in a three stimulus oddball experiment. The three stimulus
oddball paradigm was aimed to test the hypothesis that individuals with autism abnormally orient their attention to novel
distracters as compared to controls. A dense-array 128 channel EGI electroencephalographic (EEG) system was used on 11 high-functioning
children and young adults with autism spectrum disorder (ASD) and 11 age-matched, typically developing control subjects. Patients
with ASD showed slower reaction times but did not differ in response accuracy. At the anterior (frontal) topography the ASD
group showed significantly higher amplitudes and longer latencies of early ERP components (e.g., P100, N100) to novel distracter
stimuli in both hemispheres. The ASD group also showed prolonged latencies of late ERP components (e.g., P2a, N200, P3a) to
novel distracter stimuli in both hemispheres. However, differences were more profound in the right hemisphere for both early
and late ERP components. Our results indicate augmented and prolonged early frontal potentials and a delayed P3a component
to novel stimuli, which suggest low selectivity in pre-processing and later-stage under-activation of integrative regions
in the prefrontal cortices. Also, at the posterior (centro-parietal) topography the ASD group showed significantly prolonged
N100 latencies and reduced amplitudes of the N2b component to target stimuli. In addition, the latency of the P3b component
was prolonged to novel distracters in the ASD group. In general, the autistic group showed prolonged latencies to novel stimuli
especially in the right hemisphere. These results suggest that individuals with autism over-process information needed for
the successful differentiation of target and novel stimuli. We propose the potential application of ERP evaluations in a novelty
task as outcome measurements in the biobehavioral treatment (e.g., EEG biofeedback, TMS) of autism. 相似文献
978.
Allan M. Ramirez Cherry Wongtrakool Teresa Welch Andreas Steinmeyer Ulrich Zügel Jesse Roman 《The Journal of steroid biochemistry and molecular biology》2010,118(3):142-150
The mechanisms that control fibroproliferation and matrix deposition in lung fibrosis remain unclear. We speculate that vitamin D deficiency may contribute to pulmonary fibrosis since vitamin D deficiency has been implicated in several diseases. First, we confirmed the presence of vitamin D receptors (VDRs) in cultured NIH/3T3 and lung fibroblasts. Fibroblasts transfected with a vitamin D response element–reporter construct and exposed to the active vitamin D metabolite, 1,25(OH)2D3, showed increased promoter activity indicating VDR functionality in these cells. Testing the effects of 1,25(OH)2D3 on fibroblasts treated with transforming growth factor β1 (TGFβ1), considered a driver of many fibrotic disorders, we found that 1,25(OH)2D3 inhibited TGFβ1-induced fibroblast proliferation in a dose-dependent fashion. 1,25(OH)2D3 also inhibited TGFβ1 stimulation of α-smooth muscle actin expression and polymerization and prevented the upregulation of fibronectin and collagen in TGFβ1-treated fibroblasts. Finally, we examined how 1,25(OH)2D3 affects epithelial–mesenchymal transformation of lung epithelial cells upon exposure to TGFβ1. We showed that the TGFβ1-induced upregulation of mesenchymal cell markers and abnormal expression of epithelial cell markers were blunted by 1,25(OH)2D3. These observations suggest that under TGFβ1 stimulation, 1,25(OH)2D3 inhibits the pro-fibrotic phenotype of lung fibroblasts and epithelial cells. 相似文献
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980.
Herbivory in global climate change research: direct effects of rising temperature on insect herbivores 总被引:19,自引:0,他引:19
Jeffery S. Bale Gregory J. Masters Ian D. Hodkinson Caroline Awmack † T. Martijn Bezemer Valerie K. Brown ‡ Jennifer Butterfield Alan Buse John C. Coulson John Farrar John E. G. Good Richard Harrington Susane Hartley § T. Hefin Jones Richard L. Lindroth Malcolm C. Press Ilias Symrnioudis Allan D. Watt John B. Whittaker 《Global Change Biology》2002,8(1):1-16
This review examines the direct effects of climate change on insect herbivores. Temperature is identified as the dominant abiotic factor directly affecting herbivorous insects. There is little evidence of any direct effects of CO2 or UVB. Direct impacts of precipitation have been largely neglected in current research on climate change. Temperature directly affects development, survival, range and abundance. Species with a large geographical range will tend to be less affected. The main effect of temperature in temperate regions is to influence winter survival; at more northerly latitudes, higher temperatures extend the summer season, increasing the available thermal budget for growth and reproduction. Photoperiod is the dominant cue for the seasonal synchrony of temperate insects, but their thermal requirements may differ at different times of year. Interactions between photoperiod and temperature determine phenology; the two factors do not necessarily operate in tandem. Insect herbivores show a number of distinct life‐history strategies to exploit plants with different growth forms and strategies, which will be differentially affected by climate warming. There are still many challenges facing biologists in predicting and monitoring the impacts of climate change. Future research needs to consider insect herbivore phenotypic and genotypic flexibility, their responses to global change parameters operating in concert, and awareness that some patterns may only become apparent in the longer term. 相似文献