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71.
Michael Kessler Dietrich Hertel Hermann F. Jungkunst Jürgen Kluge Stefan Abrahamczyk Merijn Bos Damayanti Buchori Gerhard Gerold S. Robbert Gradstein Stefan K?hler Christoph Leuschner Gerald Moser Ramadhanil Pitopang Shahabuddin Saleh Christian H. Schulze Simone G. Sporn Ingolf Steffan-Dewenter Sri S. Tjitrosoedirdjo Teja Tscharntke 《PloS one》2012,7(10)
Managing ecosystems for carbon storage may also benefit biodiversity conservation, but such a potential ‘win-win’ scenario has not yet been assessed for tropical agroforestry landscapes. We measured above- and below-ground carbon stocks as well as the species richness of four groups of plants and eight of animals on 14 representative plots in Sulawesi, Indonesia, ranging from natural rainforest to cacao agroforests that have replaced former natural forest. The conversion of natural forests with carbon stocks of 227–362 Mg C ha−1 to agroforests with 82–211 Mg C ha−1 showed no relationships to overall biodiversity but led to a significant loss of forest-related species richness. We conclude that the conservation of the forest-related biodiversity, and to a lesser degree of carbon stocks, mainly depends on the preservation of natural forest habitats. In the three most carbon-rich agroforestry systems, carbon stocks were about 60% of those of natural forest, suggesting that 1.6 ha of optimally managed agroforest can contribute to the conservation of carbon stocks as much as 1 ha of natural forest. However, agroforestry systems had comparatively low biodiversity, and we found no evidence for a tight link between carbon storage and biodiversity. Yet, potential win-win agroforestry management solutions include combining high shade-tree quality which favours biodiversity with cacao-yield adapted shade levels. 相似文献
72.
Temudo MF Muyzer G Kleerebezem R van Loosdrecht MC 《Applied microbiology and biotechnology》2008,80(6):1121-1130
Anaerobic fermentation by an open mixed culture was investigated at different pH values (4–8.5) and with three substrates
(glucose, glycerol and xylose). The populations established in each condition were assessed by denaturing gradient gel electrophoresis
analysis of the 16S ribosomal RNA gene fragments. The fermentation pattern and the composition of the microbial population
were also evaluated when operational variations were imposed (increase of substrate concentration or introduction of a second
substrate). The experimental results demonstrated that at low and high pH values, a clearly different fermentation pattern
was associated with the dominance of a specialised group of clostridiae. At intermediate pH values, the product spectrum was
rather variable and seemed to be sensitive to variations in the microbial community. Different substrates resulted in the
establishment of different microbial communities. When fed with a mixture of two substrates, mixotrophic microorganisms (capable
of degrading both substrates) were found to overgrow the originally dominant specialists. Overall, the experiments have shown
that some operational variables have a clear impact on the fermentation pattern and on the population established. However,
a uniform relationship between the process characteristics (associated to a metabolic response) and the microbial population
present is not always possible.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
73.
Using hierarchical levels for urban ecology 总被引:1,自引:0,他引:1
74.
Andrew J Vickers Rebecca W Rees Catherine E Zollman Rob McCarney Claire M Smith Nadia Ellis Peter Fisher Robbert Van Haselen 《BMJ (Clinical research ed.)》2004,328(7442):744
Objective To determine the effects of a policy of “use acupuncture” on headache, health status, days off sick, and use of resources in patients with chronic headache compared with a policy of “avoid acupuncture.”Design Randomised, controlled trial.Setting General practices in England and Wales.Participants 401 patients with chronic headache, predominantly migraine.Interventions Patients were randomly allocated to receive up to 12 acupuncture treatments over three months or to a control intervention offering usual care.Main outcome measures Headache score, SF-36 health status, and use of medication were assessed at baseline, three, and 12 months. Use of resources was assessed every three months.Results Headache score at 12 months, the primary end point, was lower in the acupuncture group (16.2, SD 13.7, n = 161, 34% reduction from baseline) than in controls (22.3, SD 17.0, n = 140, 16% reduction from baseline). The adjusted difference between means is 4.6 (95% confidence interval 2.2 to 7.0; P = 0.0002). This result is robust to sensitivity analysis incorporating imputation for missing data. Patients in the acupuncture group experienced the equivalent of 22 fewer days of headache per year (8 to 38). SF-36 data favoured acupuncture, although differences reached significance only for physical role functioning, energy, and change in health. Compared with controls, patients randomised to acupuncture used 15% less medication (P = 0.02), made 25% fewer visits to general practitioners (P = 0.10), and took 15% fewer days off sick (P = 0.2).Conclusions Acupuncture leads to persisting, clinically relevant benefits for primary care patients with chronic headache, particularly migraine. Expansion of NHS acupuncture services should be considered. 相似文献
75.
76.
Sleep deprivation is a common feature in modern society, and one of the consequences of sleep loss is the impairment of cognitive function. Although it has been widely accepted that sleep deprivation affects learning and memory, only recently has research begun to address which molecular signaling pathways are altered by sleep loss and, more importantly, which pathways can be targeted to reverse the memory impairments resulting from sleep deprivation. In this review, we discuss the different methods used to sleep deprive animals and the effects of different durations of sleep deprivation on learning and memory with an emphasis on hippocampus-dependent memory. We then review the molecular signaling pathways that are sensitive to sleep loss, with a focus on those thought to play a critical role in the memory and synaptic plasticity deficits observed after sleep deprivation. Finally, we highlight several recent attempts to reverse the effects of sleep deprivation on memory and synaptic plasticity. Future research building on these studies promises to contribute to the development of novel strategies to ameliorate the effects of sleep loss on cognition. 相似文献
77.
Viral persistence alters CD8 T-cell immunodominance and tissue distribution and results in distinct stages of functional impairment 总被引:13,自引:0,他引:13 下载免费PDF全文
Wherry EJ Blattman JN Murali-Krishna K van der Most R Ahmed R 《Journal of virology》2003,77(8):4911-4927
Chronic viral infections often result in ineffective CD8 T-cell responses due to functional exhaustion or physical deletion of virus-specific T cells. However, how persisting virus impacts various CD8 T-cell effector functions and influences other aspects of CD8 T-cell dynamics, such as immunodominance and tissue distribution, remains largely unknown. Using different strains of lymphocytic choriomeningitis virus (LCMV), we compared responses to the same CD8 T-cell epitopes during acute or chronic infection. Persistent infection led to a disruption of the normal immunodominance hierarchy of CD8 T-cell responses seen following acute infection and dramatically altered the tissue distribution of LCMV-specific CD8 T cells in lymphoid and nonlymphoid tissues. Most importantly, CD8 T-cell functional impairment occurred in a hierarchical fashion in chronically infected mice. Production of interleukin 2 and the ability to lyse target cells in vitro were the first functions compromised, followed by the ability to make tumor necrosis factor alpha, while gamma interferon production was most resistant to functional exhaustion. Antigen appeared to be the driving force for this loss of function, since a strong correlation existed between the viral load and the level of exhaustion. Further, epitopes presented at higher levels in vivo resulted in physical deletion, while those presented at lower levels induced functional exhaustion. A model is proposed in which antigen levels drive the hierarchical loss of different CD8 T-cell effector functions during chronic infection, leading to distinct stages of functional impairment and eventually to physical deletion of virus-specific T cells. These results have implications for the study of human chronic infections, where similar T-cell deletion and functional dysregulation has been observed. 相似文献
78.
Citric acid (CA) was evaluated as a functionality-enhancing monomer in biobased polyesters suitable for coating applications. Model reactions of CA with several primary and secondary alcohols and diols, including the 1,4:3,6-dianhydrohexitols, revealed that titanium(IV) n-butoxide catalyzed esterification reactions involving these compounds proceed at relatively low temperatures, often via anhydride intermediates. Interestingly, the facile anhydride formation from CA at temperatures around CA's melting temperature ( T m = 153 degrees C) proved to be crucial in modifying sterically hindered secondary hydroxyl end groups. OH-functional polyesters were reacted with CA in the melt between 150 and 165 degrees C, yielding slightly branched carboxylic acid functional materials with strongly enhanced functionality. The acid/epoxy curing reaction of the acid-functional polymers was simulated with a monofunctional glycidyl ether. Finally, the CA-modified polyesters were applied as coatings, using conventional cross-linking agents. The formulations showed rapid curing, resulting in chemically and mechanically stable coatings. These results demonstrate that citric acid can be applied in a new way, making use of its anhydride formation to functionalize OH-functional polyesters, which is an important new step toward fully biobased coating systems. 相似文献
79.
Anniek B. van der Waart Walter J. F. M. van der Velden Astrid G. S. van Halteren Marij J. L. G. Leenders Ton Feuth Nicole M. A. Blijlevens Robbert van der Voort Harry Dolstra 《PloS one》2012,7(12)
The C-type lectin-like receptor CD161 is a well-established marker for human IL17-producing T cells, which have been implicated to contribute to the development of graft-versus-host disease (GVHD) after allogeneic stem cell transplantation (allo-SCT). In this study, we analyzed CD161+ T cell recovery, their functional properties and association with GVHD occurrence in allo-SCT recipients. While CD161+CD4+ T cells steadily recovered, CD161hiCD8+ T cell numbers declined during tapering of Cyclosporine A (CsA), which can be explained by their initial growth advantage over CD161neg/lowCD8+ T cells due to ABCB1-mediated CsA efflux. Interestingly, occurrence of acute and chronic GVHD was significantly correlated with decreased levels of circulating CD161+CD4+ as well as CD161hiCD8+ T cells. In addition, these subsets from transplanted patients secreted high levels of IFNγ and IL17. Moreover, we found that CCR6 co-expression by CD161+ T cells mediated specific migration towards CCL20, which was expressed in GVHD biopsies. Finally, we demonstrated that CCR6+ T cells indeed were present in these CCL20+ GVHD-affected tissues. In conclusion, we showed that functional CD161+CCR6+ co-expressing T cells disappear from the circulation and home to GVHD-affected tissue sites. These findings support the hypothesis that CCR6+CD161-expressing T cells may be involved in the immune pathology of GVHD following their CCL20-dependent recruitment into affected tissues. 相似文献
80.
Pier Woudstra Peter Damman Wichert J. Kuijt Wouter J. Kikkert Maik J. Grundeken Peter M. van Brussel An K. Stroobants Jan P. van Straalen Johan C. Fischer Karel T. Koch José P. S. Henriques Jan J. Piek Jan G. P. Tijssen Robbert J. de Winter 《PloS one》2014,9(5)