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71.
Pete Beckman Kamil Iskra Kazutomo Yoshii Susan Coghlan Aroon Nataraj 《Cluster computing》2008,11(1):3-16
We investigate operating system noise, which we identify as one of the main reasons for a lack of synchronicity in parallel
applications. Using a microbenchmark, we measure the noise on several contemporary platforms and find that, even with a general-purpose
operating system, noise can be limited if certain precautions are taken. We then inject artificially generated noise into
a massively parallel system and measure its influence on the performance of collective operations. Our experiments indicate
that on extreme-scale platforms, the performance is correlated with the largest interruption to the application, even if the
probability of such an interruption on a single process is extremely small. We demonstrate that synchronizing the noise can
significantly reduce its negative influence.
相似文献
Aroon NatarajEmail: |
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We propose operational definitions of reproductive optimism and pessimism; optimism involves behaving in a way that gives too much weight (in terms of producing surviving offspring) to positive events, pessimism gives too much weight to negative events. Natural selection maximizes the long-term growth of a lineage rather than short-term measures such as numbers of offspring. Consequently, optimism or pessimism can be favoured by natural selection, even though such biases appear irrational from a short-term perspective. We investigate the evolution of optimism in a metapopulation. The circumstances of a patch change over time, independently of other patches. With sufficient dispersal between patches, stochasticity affects members of a lineage largely independently and optimism is favoured. With little dispersal, the temporal fluctuations of a patch affect many members similarly; pessimism is then favoured. Our results establish that the spatial and temporal structure of the environment is crucial in determining the direction of evolved biases. 相似文献
75.
Andy D. Robertson Pete Smith Andy W. Stott Emily L. Clark Niall P. McNamara 《Bioenergy Research》2017,10(1):86-101
The carbon (C) dynamics of a bioenergy system are key to correctly defining its viability as a sustainable alternative to conventional fossil fuel energy sources. Recent studies have quantified the greenhouse gas mitigation potential of these bioenergy crops, often concluding that C sequestration in soils plays a primary role in offsetting emissions through energy generation. Miscanthus is a particularly promising bioenergy crop and research has shown that soil C stocks can increase by more than 2 t C ha?1 yr?1. In this study, we use a stable isotope (13C) technique to trace the inputs and outputs from soils below a commercial Miscanthus plantation in Lincolnshire, UK, over the first 7 years of growth after conversion from a conventional arable crop. Results suggest that an unchanging total topsoil (0–30 cm) C stock is caused by Miscanthus additions displacing older soil organic matter. Further, using a comparison between bare soil plots (no new Miscanthus inputs) and undisturbed Miscanthus controls, soil respiration was seen to be unaffected through priming by fresh inputs or rhizosphere. The temperature sensitivity of old soil C was also seen to be very similar with and without the presence of live root biomass. Total soil respiration from control plots was dominated by Miscanthus-derived emissions with autotrophic respiration alone accounting for ~50 % of CO2. Although total soil C stocks did not change significantly over time, the Miscanthus-derived soil C accumulated at a rate of 860 kg C ha?1 yr?1 over the top 30 cm. Ultimately, the results from this study indicate that soil C stocks below Miscanthus plantations do not necessarily increase during the first 7 years. 相似文献
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77.
Zhao X Deyanova EG Lubbers LS Zafian P Li JJ Liaw A Song Q Du Y Settlage RE Hickey GJ Yates NA Hendrickson RC 《Journal of proteome research》2008,7(10):4373-4383
Estrogens are a class of steroid hormones that interact with two related but distinct nuclear receptors, estrogen receptor (ER) alpha and beta. To identify potential ER biomarkers, we profiled the rat plasma glycoproteome after treatment with vehicle or 17beta-estradiol (E2) or an ERalpha-selective agonist PPT by differential mass spectrometry. Our comparative proteomic experiment identifies novel E2- and PPT-responsive proteins, such as serine protease inhibitor family members. 相似文献
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Shaista Nisar Eamonn Kelly Pete J. Cullen Stuart J. Mundell 《Traffic (Copenhagen, Denmark)》2010,11(4):508-519
The activity and traffic of G‐protein coupled receptors (GPCRs) is tightly controlled. Recent work from our laboratory has shown that P2Y1 and P2Y12 responsiveness is rapidly and reversibly modulated in human platelets and that the underlying mechanism requires receptor trafficking as an essential part of this process. However, little is known about the molecular mechanisms underlying P2Y receptor traffic. Sorting nexin 1 (SNX1) has been shown to regulate the endosomal sorting of cell surface receptors either to lysosomes where they are downregulated or back to the cell surface. These functions may in part be due to interactions of SNX1 with the mammalian retromer complex. In this study, we investigated the role of SNX1 in P2Y receptor trafficking. We show that P2Y1 receptors recycle via a slow recycling pathway that is regulated by SNX1, whereas P2Y12 receptors return to the cell surface via a rapid route that is SNX1 independent. SNX1 inhibition caused a dramatic increase in the rate of P2Y1 receptor recycling, whereas inhibition of Vps26 and Vps35 known to be present in retromer had no effect, indicating that SNX1 regulation of P2Y1 receptor recycling is retromer independent. In addition, inhibition of SNX4, 6 and 17 proteins did not affect P2Y1 receptor recycling. SNX1 has also been implicated in GPCR degradation; however, we provide evidence that P2Y receptor degradation is SNX1 independent. These data describe a novel function of SNX1 in the regulation of P2Y1 receptor recycling and suggest that SNX1 plays multiple roles in endocytic trafficking of GPCRs. 相似文献
80.
The interleukin-1 gene family encodes a group of related proteins that exhibit a remarkable pleiotropy in the context of health and disease. The set of indispensable functions they control suggests that these genes should be found in all eukaryotic species. The ligands and receptors of this family have been primarily characterised in man and mouse. The genomes of most non-mammalian animal species sequenced so far possess all of the IL-1 receptor genes found in mammals. Yet, strikingly, very few of the ligands are identifiable in non-mammalian genomes. Our recent identification of two further IL-1 ligands in the chicken warranted a critical reappraisal of the evolution of this vitally important cytokine family. This review presents substantial data gathered across multiple, divergent metazoan genomes to unambiguously trace the origin of these genes. With the hypothesis that all of these genes, both ligands and receptors, were formed in a single ancient ancestor, extensive database mining revealed sufficient evidence to confirm this. It therefore suggests that the emergence of mammals is unrelated to the expansion of the IL-1 family. A thorough review of this cytokine family in the chicken, the most extensively studied amongst non-mammalian species, is also presented. 相似文献