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991.
Chen LL Gabarra V Cho S Browning B Cao X Huet H Cheung A Morena R Ramirez M Shields M Blake Pepinsky R McLachlan K 《Cell communication & adhesion》2008,15(4):317-331
Integrin alpha6beta4-mediated adhesion interactions play key roles in keratinocyte and epithelial tumor cell biology. In order to evaluate how alpha6beta4 adhesion interactions contribute to these important cellular processes, the authors generated soluble versions of the integrin by recombinant expression of the subunit ectodomains fused to a human immunoglobulin G (IgG) Fc constant domain. Coexpression of the appropriate subunits enabled dimerization, secretion and purification of stable Fc-containing alpha6beta4 heterodimers. The soluble proteins exhibited the same metal ion and ligand dependency in their binding characteristics as intact alpha6beta4. Using these reagents in combination with anti-beta4 antibodies, the authors identified two distinct functional epitopes on the beta4 subunit. They demonstrated the involvement of one epitope in adhesion interactions and the other in regulating adhesion-independent growth in alpha6beta4-expressing tumor cell lines. The availability of these soluble integrin reagents and the data provided herein help to further delineate the structure-function relationships regulating alpha6beta4 signaling biology. 相似文献
992.
Mobiluncus curtisii was isolated from the blood of a 35-year-old man with a medical history of ulcerative colitis who was admitted unconscious to the Intensive Care Unit (ICU). A CT scan revealed massive intracerebral hemorrhage in the left hemisphere. Temperature remained constant over 38.5 degrees C; therefore, two sets of blood cultures were collected. One anaerobic bottle BacT/ALERT SN (bioMerieux, France) was detected as positive after 5 days of incubation and a Gram stain confirmed a gram variable curved-shaped rod. The patient died 18 h after being admitted to the hospital. 相似文献
993.
994.
Wide-confocal-cytometry (WCC) is a new method developed in this paper that uses a standard confocal system to gather quantitative
information on contents and fine structural details of cells. The system is operated under conditions of non-confocality,
in order to capture the maximum amount of light emitted by the specimen (comparable to LSC). After analysis of macromolecule
content (DNA, RNA, specific proteins, lipids, etc.), cells can be sampled using conventional confocal microscopy. We analyzed
the illumination and acquiring capabilities of WCC. The quantitative power of WCC was validated by analysis of cell cycle
stage in Hela cells, looking at DNA content and markers for S phase and mitosis. As an example of the potential of this methodology
we have documented changes in cell nucleus during the cell cycle. After mitosis the cell nucleus changes its shape from elongated
to ellipsoid and remains constant until G2. This change is associated with nuclear volume increase. As nuclear volume increases,
chromatin becomes decondensed in an isometric manner, probably due to the increase in gene expression and factors necessary
for RNA metabolism. 相似文献
995.
Azospirillum amazonense inoculation: effects on growth, yield and N2 fixation of rice (Oryza sativa L.) 总被引:1,自引:0,他引:1
Elisete Pains Rodrigues Luciana Santos Rodrigues André Luiz Martinez de Oliveira Vera Lucia Divan Baldani Kátia Regina dos Santos Teixeira Segundo Urquiaga Veronica Massena Reis 《Plant and Soil》2008,302(1-2):249-261
Bacteria of the genus Azospirillum are considered to be plant-growth promoting bacteria (PGPR) and stimulate plant growth directly either by synthesising phyto-hormones
or by promoting nutrition by the process of biological nitrogen fixation (BNF). Although this genus extensively studied, the
effects of inoculation and the possible BNF contribution of the Azospirillum amazonense specie are very scarce. The aim of this study was to isolate, characterise and evaluate auxin production and nitrogenase
activity of this species and to select, by inoculation of rice plants, promising isolates based on their ability to improve
plant growth, yield and the BNF contribution. One hundred and ten isolates obtained from rice were characterised and grouped
according to colony features. Forty-two isolates, confirmed as A. amazonense by the fluorescent in situ hybridization (FISH) technique, were tested for auxin production and nitrogenase activity in vitro.
Subsequently plant growth promotion related to plant nutrition effect was evaluated, in vitro and in greenhouse experiments.
The BNF contribution to plant growth was evaluated using the 15N isotope dilution technique. All A. amazonense strains tested produced indoles, but only 10% of them showed high production, above 1.33 μM mg protein−1. The nitrogenase activity also was variable and only 9% of isolates showed high nitrogenase activity and the majority (54%)
exhibited a low potential. The inoculation of selected strains in rice under gnotobiotic conditions reduced the growth of
root and aerial part when compared to the control, showing the negative effects of excess of phytohormone accumulation in
the medium. However, in the greenhouse experiment, inoculation of strains of A. amazonense increased grain dry matter accumulation (7 to 11.6%), the number of panicles (3 to 18.6%) and nitrogen accumulation at grain
maturation (3.5 to 18.5%). BNF contributions up to 27% were observed for A. amazonense Y2 (wild type strain). The data presented here is the first report that the PGPR effect of A. amazonense for rice plants grown under greenhouse conditions is mainly due the BNF contribution as measured by 15N isotope dilution technique, in contrast to the hormonal effect observed with other Azospirillum species studied. 相似文献
996.
In this study, we analyzed the biological and physical organ dose equivalents for International Space Station (ISS) astronauts. Individual physical dosimetry is difficult in space due to the complexity of the space radiation environment, which consists of protons, heavy ions and secondary neutrons, and the modification of these radiation types in tissue as well as limitations in dosimeter devices that can be worn for several months in outer space. Astronauts returning from missions to the ISS undergo biodosimetry assessment of chromosomal damage in lymphocyte cells using the multicolor fluorescence in situ hybridization (FISH) technique. Individual-based pre-flight dose responses for lymphocyte exposure in vitro to gamma rays were compared to those exposed to space radiation in vivo to determine an equivalent biological dose. We compared the ISS biodosimetry results, NASA's space radiation transport models of organ dose equivalents, and results from ISS and space shuttle phantom torso experiments. Physical and biological doses for 19 ISS astronauts yielded average effective doses and individual or population-based biological doses for the approximately 6-month missions of 72 mSv and 85 or 81 mGy-Eq, respectively. Analyses showed that 80% or more of organ dose equivalents on the ISS are from galactic cosmic rays and only a small contribution is from trapped protons and that GCR doses were decreased by the high level of solar activity in recent years. Comparisons of models to data showed that space radiation effective doses can be predicted to within about a +/-10% accuracy by space radiation transport models. Finally, effective dose estimates for all previous NASA missions are summarized. 相似文献
997.
Global response of terrestrial ecosystem structure and function to CO2 and climate change: results from six dynamic global vegetation models 总被引:4,自引:0,他引:4
Wolfgang Cramer Alberte Bondeau F. Ian Woodward † I. Colin Prentice ‡ Richard A. Betts § Victor Brovkin † Peter M. Cox § Veronica Fisher ¶ Jonathan A. Foley ¶ rew D. Friend Chris Kucharik ¶ Mark R. Lomas † Navin Ramankutty ¶ Stephen Sitch Benjamin Smith †† rew White Christine Young-Molling¶ 《Global Change Biology》2001,7(4):357-373
The possible responses of ecosystem processes to rising atmospheric CO2 concentration and climate change are illustrated using six dynamic global vegetation models that explicitly represent the interactions of ecosystem carbon and water exchanges with vegetation dynamics. The models are driven by the IPCC IS92a scenario of rising CO2 ( Wigley et al. 1991 ), and by climate changes resulting from effective CO2 concentrations corresponding to IS92a, simulated by the coupled ocean atmosphere model HadCM2‐SUL. Simulations with changing CO2 alone show a widely distributed terrestrial carbon sink of 1.4–3.8 Pg C y?1 during the 1990s, rising to 3.7–8.6 Pg C y?1 a century later. Simulations including climate change show a reduced sink both today (0.6–3.0 Pg C y?1) and a century later (0.3–6.6 Pg C y?1) as a result of the impacts of climate change on NEP of tropical and southern hemisphere ecosystems. In all models, the rate of increase of NEP begins to level off around 2030 as a consequence of the ‘diminishing return’ of physiological CO2 effects at high CO2 concentrations. Four out of the six models show a further, climate‐induced decline in NEP resulting from increased heterotrophic respiration and declining tropical NPP after 2050. Changes in vegetation structure influence the magnitude and spatial pattern of the carbon sink and, in combination with changing climate, also freshwater availability (runoff). It is shown that these changes, once set in motion, would continue to evolve for at least a century even if atmospheric CO2 concentration and climate could be instantaneously stabilized. The results should be considered illustrative in the sense that the choice of CO2 concentration scenario was arbitrary and only one climate model scenario was used. However, the results serve to indicate a range of possible biospheric responses to CO2 and climate change. They reveal major uncertainties about the response of NEP to climate change resulting, primarily, from differences in the way that modelled global NPP responds to a changing climate. The simulations illustrate, however, that the magnitude of possible biospheric influences on the carbon balance requires that this factor is taken into account for future scenarios of atmospheric CO2 and climate change. 相似文献
998.
Min‐Xu Li Min Jia Li‐Xia Yang Veronica Dunlap Phillip G. Nelson 《Developmental neurobiology》2002,52(3):241-250
We have used a three compartment tissue culture system that involved two separate populations of cholinergic neurons in the side compartments that converged on a common target population of myotubes in the center compartment. Activation of the axons from one population of neurons produced selective down‐regulation of the synaptic inputs from the other neuronal population (when the two inputs innervated the same myotubes). The decrease in heterosynaptic inputs was mediated by protein kinase C (PKC). An activity‐dependent action of protein kinase A (PKA) was associated with the stimulated input and this served to selectively stabilize this input. These changes associated with PKA and PKC activation were mediated by alterations in the number of acetylcholine receptors at the neuromuscular junction. These results suggest that neuromuscular electrical activity produces postsynaptic activation of both PKA and PKC, with the latter producing generalized synapse weakening and the former a selective synapse stabilization. Treatment of the neuronal cell body and axon to increase PKC activity by putting phorbal ester (PMA) in the side chamber did not affect synaptic transmission (with or without stimulation). By contrast, PKA blockade in the side compartment did produce an activity‐dependent decrease in synaptic efficacy, which was due to a decrease in quantal release of neurotransmitter. Thus, when the synapse is activated, it appears that presynaptic PKA action is necessary to maintain transmitter output. Published 2002 Wiley Periodicals, Inc. J Neurobiol 52: 241–250, 2002 相似文献
999.
The red harvester ant, Pogonomyrmex barbatus, is a monogynous, polyandrous species: each ant colony is founded by a single queen that has mated with one or more males. To study levels of polyandry within a colony, as well as relationships among colonies, we developed 10 polymorphic microsatellite loci for P. barbatus. With the number of alleles per locus ranging from 3 to 39, and expected heterozygosities of 0.58–0.95, these markers promise to be useful in the study of colony and population genetic structure. 相似文献
1000.
Complete genome sequence of the industrial bacterium Bacillus licheniformis and comparisons with closely related Bacillus species 总被引:2,自引:0,他引:2 下载免费PDF全文
Rey MW Ramaiya P Nelson BA Brody-Karpin SD Zaretsky EJ Tang M Lopez de Leon A Xiang H Gusti V Clausen IG Olsen PB Rasmussen MD Andersen JT Jørgensen PL Larsen TS Sorokin A Bolotin A Lapidus A Galleron N Ehrlich SD Berka RM 《Genome biology》2004,5(10):r77-12