全文获取类型
收费全文 | 88篇 |
免费 | 3篇 |
国内免费 | 1篇 |
出版年
2023年 | 1篇 |
2022年 | 1篇 |
2021年 | 2篇 |
2020年 | 1篇 |
2019年 | 1篇 |
2018年 | 1篇 |
2016年 | 4篇 |
2015年 | 8篇 |
2014年 | 5篇 |
2013年 | 7篇 |
2012年 | 7篇 |
2011年 | 8篇 |
2010年 | 5篇 |
2009年 | 1篇 |
2008年 | 3篇 |
2007年 | 2篇 |
2006年 | 6篇 |
2005年 | 3篇 |
2004年 | 2篇 |
2003年 | 5篇 |
2002年 | 6篇 |
2001年 | 2篇 |
1999年 | 1篇 |
1998年 | 1篇 |
1996年 | 1篇 |
1992年 | 1篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1987年 | 1篇 |
1984年 | 1篇 |
1939年 | 1篇 |
1905年 | 1篇 |
1903年 | 1篇 |
排序方式: 共有92条查询结果,搜索用时 15 毫秒
41.
Pedro Fernández-Soto Prosper Obolo Mvoulouga Jean Paul Akue Julio López Abán Belén Vicente Santiago Miguel Cordero Sánchez Antonio Muro 《PloS one》2014,9(4)
The filarial parasite Loa loa, the causative agent of loiasis, is endemic in Central and Western Africa infecting 3–13 million people. L. loa has been associated with fatal encephalopathic reactions in high Loa-infected individuals receiving ivermectin during mass drug administration programs for the control of onchocerciasis and lymphatic filariasis. In endemic areas, the only diagnostic method routinely used is the microscopic examination of mid-day blood samples by thick blood film. Improved methods for detection of L. loa are needed in endemic regions with limited resources, where delayed diagnosis results in high mortality. We have investigated the use of a loop-mediated isothermal amplification (LAMP) assay to facilitate rapid, inexpensive, molecular diagnosis of loiasis. Primers for LAMP were designed from a species-specific repetitive DNA sequence from L. loa retrieved from GenBank. Genomic DNA of a L. loa adult worm was used to optimize the LAMP conditions using a thermocycler or a conventional heating block. Amplification of DNA in the LAMP mixture was visually inspected for turbidity as well as addition of fluorescent dye. LAMP specificity was evaluated using DNA from other parasites; sensitivity was evaluated using DNA from L. loa 10-fold serially diluted. Simulated human blood samples spiked with DNA from L. loa were also tested for sensitivity. Upon addition of fluorescent dye, all positive reactions turned green while the negative controls remained orange under ambient light. After electrophoresis on agarose gels, a ladder of multiple bands of different sizes could be observed in positive samples. The detection limit of the assay was found to be as little as 0.5 ag of L. loa genomic DNA when using a heating block. We have designed, for the first time, a highly sensitive LAMP assay for the detection of L. loa which is potentially adaptable for field diagnosis and disease surveillance in loiasis-endemic areas. 相似文献
42.
Meeting cholera's challenge to Haiti and the world: a joint statement on cholera prevention and care
Farmer P Almazor CP Bahnsen ET Barry D Bazile J Bloom BR Bose N Brewer T Calderwood SB Clemens JD Cravioto A Eustache E Jérôme G Gupta N Harris JB Hiatt HH Holstein C Hotez PJ Ivers LC Kerry VB Koenig SP Larocque RC Léandre F Lambert W Lyon E Mekalanos JJ Mukherjee JS Oswald C Pape JW Gretchko Prosper A Rabinovich R Raymonville M Réjouit JR Ronan LJ Rosenberg ML Ryan ET Sachs JD Sack DA Surena C Suri AA Ternier R Waldor MK Walton D Weigel JL 《PLoS neglected tropical diseases》2011,5(5):e1145
43.
Robbins MM Gray M Fawcett KA Nutter FB Uwingeli P Mburanumwe I Kagoda E Basabose A Stoinski TS Cranfield MR Byamukama J Spelman LH Robbins AM 《PloS one》2011,6(6):e19788
As wildlife populations are declining, conservationists are under increasing pressure to measure the effectiveness of different management strategies. Conventional conservation measures such as law enforcement and community development projects are typically designed to minimize negative human influences upon a species and its ecosystem. In contrast, we define "extreme" conservation as efforts targeted to deliberately increase positive human influences, including veterinary care and close monitoring of individual animals. Here we compare the impact of both conservation approaches upon the population growth rate of the critically endangered Virunga mountain gorillas (Gorilla beringei beringei), which increased by 50% since their nadir in 1981, from approximately 250 to nearly 400 gorillas. Using demographic data from 1967-2008, we show an annual decline of 0.7%±0.059% for unhabituated gorillas that received intensive levels of conventional conservation approaches, versus an increase 4.1%±0.088% for habituated gorillas that also received extreme conservation measures. Each group of habituated gorillas is now continuously guarded by a separate team of field staff during daylight hours and receives veterinary treatment for snares, respiratory disease, and other life-threatening conditions. These results suggest that conventional conservation efforts prevented a severe decline of the overall population, but additional extreme measures were needed to achieve positive growth. Demographic stochasticity and socioecological factors had minimal impact on variability in the growth rates. Veterinary interventions could account for up to 40% of the difference in growth rates between habituated versus unhabituated gorillas, with the remaining difference likely arising from greater protection against poachers. Thus, by increasing protection and facilitating veterinary treatment, the daily monitoring of each habituated group contributed to most of the difference in growth rates. Our results argue for wider consideration of extreme measures and offer a startling view of the enormous resources that may be needed to conserve some endangered species. 相似文献
44.
Yann Mathieu Pascalita Prosper Marc Buée Stéphane Dumar?ay Frédérique Favier Eric Gelhaye Philippe Gérardin Luc Harvengt Jean-Pierre Jacquot Tiphaine Lamant Edgar Meux Sandrine Mathiot Claude Didierjean Mélanie Morel 《The Journal of biological chemistry》2012,287(46):39001-39011
Glutathione S-transferases (GSTs) form a superfamily of multifunctional proteins with essential roles in cellular detoxification processes. A new fungal specific class of GST has been highlighted by genomic approaches. The biochemical and structural characterization of one isoform of this class in Phanerochaete chrysosporium revealed original properties. The three-dimensional structure showed a new dimerization mode and specific features by comparison with the canonical GST structure. An additional β-hairpin motif in the N-terminal domain prevents the formation of the regular GST dimer and acts as a lid, which closes upon glutathione binding. Moreover, this isoform is the first described GST that contains all secondary structural elements, including helix α4′ in the C-terminal domain, of the presumed common ancestor of cytosolic GSTs (i.e. glutaredoxin 2). A sulfate binding site has been identified close to the glutathione binding site and allows the binding of 8-anilino-1-naphtalene sulfonic acid. Competition experiments between 8-anilino-1-naphtalene sulfonic acid, which has fluorescent properties, and various molecules showed that this GST binds glutathionylated and sulfated compounds but also wood extractive molecules, such as vanillin, chloronitrobenzoic acid, hydroxyacetophenone, catechins, and aldehydes, in the glutathione pocket. This enzyme could thus function as a classical GST through the addition of glutathione mainly to phenethyl isothiocyanate, but alternatively and in a competitive way, it could also act as a ligandin of wood extractive compounds. These new structural and functional properties lead us to propose that this GST belongs to a new class that we name GSTFuA, for fungal specific GST class A. 相似文献
45.
Maryke Gray Alastair McNeilage Katie Fawcett Martha M. Robbins Benard Ssebide Deo Mbula Prosper Uwingeli 《African Journal of Ecology》2010,48(3):588-599
The mountain gorillas (Gorilla beringei beringei) of the Virunga Volcanoes Range of Rwanda, Uganda, and the Democratic Republic of Congo are one of the most endangered ape populations in the world. Following a dramatic decline during the 1960s, and relative stability in the 1970s, the population steadily increased during the 1980s. Due to political instability and war, a complete census had not been conducted since 1989. Here we compare the results of a complete census using the ‘sweep method’ conducted in 2003 with those from a monitoring program, to estimate the size and distribution of the gorilla population. A total of 360 gorillas were counted from census measurements and known habituated groups. Based on quantitative assessments of the census accuracy, we calculated that an additional 20 gorillas were not counted, leading to an estimated population of 380 individuals, and a 1.15% annual growth rate since 1989. The Ranger Based Monitoring programme yielded similar results. The encouraging results must be viewed with caution, however, because the growth was concentrated almost entirely in one section of the Virungas. Additionally, the distribution of gorilla groups was negatively correlated with the frequency of human disturbances, which highlights the need to continue strengthening conservation efforts. 相似文献
46.
47.
Ulrike Fillinger Khadija Kannady George William Michael J Vanek Stefan Dongus Dickson Nyika Yvonne Geissbühler Prosper P Chaki Nico J Govella Evan M Mathenge Burton H Singer Hassan Mshinda Steven W Lindsay Marcel Tanner Deo Mtasiwa Marcia C de Castro Gerry F Killeen 《Malaria journal》2008,7(1):1-25
Background
As the population of Africa rapidly urbanizes, large populations could be protected from malaria by controlling aquatic stages of mosquitoes if cost-effective and scalable implementation systems can be designed.Methods
A recently initiated Urban Malaria Control Programme in Dar es Salaam delegates responsibility for routine mosquito control and surveillance to modestly-paid community members, known as Community-Owned Resource Persons (CORPs). New vector surveillance, larviciding and management systems were designed and evaluated in 15 city wards to allow timely collection, interpretation and reaction to entomologic monitoring data using practical procedures that rely on minimal technology. After one year of baseline data collection, operational larviciding with Bacillus thuringiensis var. israelensis commenced in March 2006 in three selected wards.Results
The procedures and staff management systems described greatly improved standards of larval surveillance relative to that reported at the outset of this programme. In the first year of the programme, over 65,000 potential Anopheles habitats were surveyed by 90 CORPs on a weekly basis. Reaction times to vector surveillance at observations were one day, week and month at ward, municipal and city levels, respectively. One year of community-based larviciding reduced transmission by the primary malaria vector, Anopheles gambiae s.l., by 31% (95% C.I. = 21.6–37.6%; p = 0.04).Conclusion
This novel management, monitoring and evaluation system for implementing routine larviciding of malaria vectors in African cities has shown considerable potential for sustained, rapidly responsive, data-driven and affordable application. Nevertheless, the true programmatic value of larviciding in urban Africa can only be established through longer-term programmes which are stably financed and allow the operational teams and management infrastructures to mature by learning from experience. 相似文献48.
Epiphytes and their contribution to canopy diversity 总被引:4,自引:0,他引:4
About ten percent of all vascular plant species world-wide are epiphytes and they are almost exclusively found in tropical forests. Therefore, they constitute a large part of the global plant biodiversity (10% of all species), and in tropical countries represent up to 25% of all vascular plant species. Focusing on the differences between epiphytes in the strict sense or holo-epiphytes (non-parasitic plants that use other plants – usually trees – as growing sites all through their life-cycle) and hemi-epiphytes (half epiphytes which only spend part of their life as epiphytes until their aerial roots become connected to the ground), horizontal and vertical distribution patterns of both in relation to some of their ecological requirements are compared. Vertical ecological gradients (i.e., insolation and humidity differences from the forest floor to the canopy surface) are relevant for the composition of the holo- epiphytic vegetation. For hemi-epiphytes, however, ecological differences between distinct forest habitats (i.e., horizontal gradients) are relevant, but not primarily the canopy structure, as the individual host tree structure is more important. The scale-dependence of epiphyte diversity assessment (relatively small study areas for holo-epiphytes, large study areas for hemi-epiphytes) is mainly due to the striking differences in plant sizes and related mechanical and physiological requirements. 相似文献
49.
In vitro differentiation of human processed lipoaspirate cells into early neural progenitors 总被引:35,自引:0,他引:35
Ashjian PH Elbarbary AS Edmonds B DeUgarte D Zhu M Zuk PA Lorenz HP Benhaim P Hedrick MH 《Plastic and reconstructive surgery》2003,111(6):1922-1931
Human processed lipoaspirate (PLA) cells are multipotent stem cells, capable of differentiating into multiple mesenchymal lineages (bone, cartilage, fat, and muscle). To date, differentiation to nonmesodermal fates has not been reported. This study demonstrates that PLA cells can be induced to differentiate into early neural progenitors, which are of an ectodermal origin. Undifferentiated cultures of human PLA cells expressed markers characteristic of neural cells such as neuron-specific enolase (NSE), vimentin, and neuron-specific nuclear protein (NeuN). After 2 weeks of treatment of PLA cells with isobutylmethylxanthine, indomethacin, and insulin, about 20 to 25 percent of the cells differentiated into cells with typical neural morphologic characteristics, accompanied by increased expression of NSE, vimentin, and the nerve-growth factor receptor trk-A. However, induced PLA cells did not express the mature neuronal marker, MAP, or the mature astrocyte marker, GFAP. It was also found that neurally induced PLA cells displayed a delayed-rectifier type K+ current (an early developmental ion channel) concomitantly with morphologic changes and increased expression of neural-specific markers. The authors concluded that human PLA cells might have the potential to differentiate in vitro into cells that represent early progenitors of neurons and/or glia. 相似文献
50.
Ellen De Langhe Frederic Cailotto Vanessa De Vooght Carolina Aznar-Lopez Jeroen Alfons Vanoirbeek Frank Prosper Luyten Rik Jozef Urbain Lories 《Respiratory research》2015,16(1)