全文获取类型
收费全文 | 518篇 |
免费 | 41篇 |
专业分类
559篇 |
出版年
2023年 | 12篇 |
2022年 | 16篇 |
2021年 | 24篇 |
2020年 | 11篇 |
2019年 | 20篇 |
2018年 | 16篇 |
2017年 | 12篇 |
2016年 | 26篇 |
2015年 | 42篇 |
2014年 | 50篇 |
2013年 | 40篇 |
2012年 | 55篇 |
2011年 | 44篇 |
2010年 | 21篇 |
2009年 | 21篇 |
2008年 | 32篇 |
2007年 | 17篇 |
2006年 | 20篇 |
2005年 | 8篇 |
2004年 | 11篇 |
2003年 | 7篇 |
2002年 | 7篇 |
2001年 | 3篇 |
2000年 | 2篇 |
1998年 | 4篇 |
1997年 | 2篇 |
1996年 | 1篇 |
1995年 | 2篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1989年 | 1篇 |
1988年 | 2篇 |
1985年 | 5篇 |
1984年 | 6篇 |
1982年 | 2篇 |
1981年 | 2篇 |
1978年 | 1篇 |
1977年 | 2篇 |
1976年 | 2篇 |
1975年 | 3篇 |
1974年 | 1篇 |
1972年 | 1篇 |
1967年 | 1篇 |
1957年 | 1篇 |
1948年 | 1篇 |
排序方式: 共有559条查询结果,搜索用时 15 毫秒
91.
Bouyer F Hamadou S Adakal H Lancelot R Stachurski F Belem AM Bouyer J 《PLoS neglected tropical diseases》2011,5(8):e1276
Background
Restricted application of insecticides to cattle is a cheap and safe farmer-based method to control tsetse. In Western Africa, it is applied using a footbath, mainly to control nagana and the tick Amblyomma variegatum. In Eastern and Southern Africa, it might help controlling the human disease, i.e., Rhodesian sleeping sickness as well. The efficiency of this new control method against ticks, tsetse and trypanosomoses has been demonstrated earlier. The invention, co-built by researchers and farmers ten years ago, became an innovation in Burkina Faso through its diffusion by two development projects.Methodology/Principal Findings
In this research, we studied the process and level of adoption in 72 farmers inhabiting the peri-urban areas of Ouagadougou and Bobo-Dioulasso. Variables describing the livestock farming system, the implementation and perception of the method and the knowledge of the epidemiological system were used to discriminate three clusters of cattle farmers that were then compared using indicators of adoption. The first cluster corresponded to modern farmers who adopted the technique very well. The more traditional farmers were discriminated into two clusters, one of which showed a good adoption rate, whereas the second failed to adopt the method. The economic benefit and the farmers'' knowledge of the epidemiological system appeared to have a low impact on the early adoption process whereas some modern practices, as well as social factors appeared critical. The quality of technical support provided to the farmers had also a great influence. Cattle farmers'' innovation-risk appraisal was analyzed using Rogers'' adoption criteria which highlighted individual variations in risk perceptions and benefits, as well as the prominent role of the socio-technical network of cattle farmers.Conclusions/Significance
Results are discussed to highlight the factors that should be taken into consideration, to move discoveries from bench to field for an improved control of trypanosomoses vectors. 相似文献92.
Steinstraesser L Koehler T Jacobsen F Daigeler A Goertz O Langer S Kesting M Steinau H Eriksson E Hirsch T 《Molecular medicine (Cambridge, Mass.)》2008,14(7-8):528-537
Host defense peptides are effector molecules of the innate immune system. They show broad antimicrobial action against gram-positive and -negative bacteria, and they likely play a key role in activating and mediating the innate as well as adaptive immune response in infection and inflammation. These features make them of high interest for wound healing research. Non-healing and infected wounds are a major problem in patient care and health care spending. Increasing infection rates, growing bacterial resistance to common antibiotics, and the lack of effective therapeutic options for the treatment of problematic wounds emphasize the need for new approaches in therapy and pathophysiologic understanding. This review focuses on the current knowledge of host defense peptides affecting wound healing and infection. We discuss the current data and highlight the potential future developments in this field of research. 相似文献
93.
Goëffon A Richer JM Hao JK 《IEEE/ACM transactions on computational biology and bioinformatics / IEEE, ACM》2008,5(1):136-145
The Maximum Parsimony (MP) problem aims at reconstructing a phylogenetic tree from DNA sequences while minimizing the number of genetic transformations. To solve this NP-complete problem, heuristic methods have been developed, often based on local search. In this article, we focus on the influence of the neighborhood relations. After analyzing the advantages and drawbacks of the well-known Nearest Neighbor Interchange (NNI), Subtree Pruning Regrafting (SPR) and Tree-Bisection-Reconnection (TBR) neighborhoods, we introduce the concept of Progressive Neighborhood (PN) which consists in constraining progressively the size of the neighborhood as the search advances. We empirically show that applied to the Maximum Parsimony problem, this progressive neighborhood turns out to be more efficient and robust than the classic neighborhoods using a descent algorithm. Indeed, it allows to find better solutions with a smaller number of iterations or trees evaluated. 相似文献
94.
95.
96.
Frantz A Plantegenest M Simon JC 《Proceedings. Biological sciences / The Royal Society》2006,273(1603):2887-2891
The evolutionary maintenance of sex, despite competition from asexual reproduction, has long intrigued the evolutionary biologists owing to its numerous apparent short-term costs. In aphids, winter climate is expected to determine the maintenance of sexual lineages in the high latitude zones owing to their exclusive ability to produce frost-resistant eggs. However, diverse reproductive modes may coexist at a local scale where climatic influence is counteracted by microgeographical factors. In this study, we tested the influence of local habitat characteristics on regional coexistence of reproductive modes in the pea aphid, Acyrthosiphon pisum. In the laboratory, the induction of sexual morph production of many pea aphid genotypes from the local fields of annual (pea and faba bean) and perennial (alfalfa and red clover) crops in Western France indicated that A. pisum lineages from annual crops had a significantly higher investment in sexual reproduction than A. pisum lineages from the perennial hosts. We propose that temporal habitat variability exerts a selective pressure to maintain the sexual reproduction in A. pisum. The ecological and evolutionary consequences of the association between the mode of reproduction and the host population on gene flow restriction and on ecological specialization are discussed. 相似文献
97.
Loucif AJ Bonnavion P Macri B Golmard JL Boni C Melfort M Leonard G Lesch KP Adrien J Jacquin TD 《Journal of neurobiology》2006,66(13):1475-1488
Agonists at G-protein-coupled receptors in neurons of the dorsal raphe nucleus (DRN) of knock-out mice devoid of the serotonin transporter (5-HTT(-/-)) exhibit lower efficacy to inhibit cellular discharge than in wild-type counterparts. Using patch-clamp whole-cell recordings, we found that a G-protein-gated inwardly rectifying potassium (GIRK) current is involved in the inhibition of spike discharge induced by 5-HT1A agonists (5-carboxamidotryptamine (5-CT) and (+/-)-2-dipropylamino-8-hydroxy-1,2,3,4-tetrahydronaphthalene hydrobromide (8-OH-DPAT); 50 nM-30 microM) in both wild-type and 5-HTT(-/-) female and male mice. These effects were mimicked by 5'-guanylyl-imido-diphosphate (Gpp(NH)p; 400 microM) dialysis into cells with differences between genders. The 5-HTT(-/-) knock-out mutation reduced the current density induced by Gpp(NH)p in females but not in males. These data suggest that the decreased response of 5-HT1A receptors to agonists in 5-HTT(-/-) mutants reflects notably alteration in the coupling between G-proteins and GIRK channels in females but not in males. Accordingly, gender differences in central 5-HT neurotransmission appear to depend-at least in part-on sex-related variations in corresponding receptor-G protein signaling mechanisms. 相似文献
98.
99.
Laser Speckle Contrast Imaging (LSCI) is a simple yet powerful technique that is used for full-field imaging of blood flow. The technique analyzes fluctuations in a dynamic speckle pattern to detect the movement of particles similar to how laser Doppler analyzes frequency shifts to determine particle speed. Because it can be used to monitor the movement of red blood cells, LSCI has become a popular tool for measuring blood flow in tissues such as the retina, skin, and brain. It has become especially useful in neuroscience where blood flow changes during physiological events like functional activation, stroke, and spreading depolarization can be quantified. LSCI is also attractive because it provides excellent spatial and temporal resolution while using inexpensive instrumentation that can easily be combined with other imaging modalities. Here we show how to build a LSCI setup and demonstrate its ability to monitor blood flow changes in the brain during an animal experiment.Download video file.(31M, mov) 相似文献
100.
Bérénice A. Benayoun Sandrine Caburet Aurélie Dipietromaria Adrien Georges Barbara D'Haene P. J. Eswari Pandaranayaka David L'H?te Anne-Laure Todeschini Sankaran Krishnaswamy Marc Fellous Elfride De Baere Reiner A. Veitia 《PloS one》2010,5(1)