全文获取类型
收费全文 | 190篇 |
免费 | 6篇 |
出版年
2022年 | 1篇 |
2021年 | 2篇 |
2020年 | 5篇 |
2019年 | 3篇 |
2018年 | 6篇 |
2017年 | 2篇 |
2016年 | 8篇 |
2015年 | 5篇 |
2014年 | 12篇 |
2013年 | 15篇 |
2012年 | 20篇 |
2011年 | 12篇 |
2010年 | 2篇 |
2009年 | 5篇 |
2008年 | 8篇 |
2007年 | 16篇 |
2006年 | 9篇 |
2005年 | 5篇 |
2004年 | 6篇 |
2003年 | 4篇 |
2002年 | 5篇 |
2000年 | 5篇 |
1999年 | 1篇 |
1996年 | 1篇 |
1993年 | 1篇 |
1986年 | 1篇 |
1984年 | 2篇 |
1980年 | 2篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1976年 | 1篇 |
1975年 | 3篇 |
1973年 | 2篇 |
1972年 | 3篇 |
1970年 | 6篇 |
1969年 | 4篇 |
1968年 | 4篇 |
1967年 | 1篇 |
1966年 | 2篇 |
1965年 | 2篇 |
排序方式: 共有196条查询结果,搜索用时 15 毫秒
31.
Emily Woollen Casey M. Ryan Sophia Baumert Frank Vollmer Isla Grundy Janet Fisher Jone Fernando Ana Luz Natasha Ribeiro Sá N. Lisboa 《Philosophical transactions of the Royal Society of London. Series B, Biological sciences》2016,371(1703)
African woodlands form a major part of the tropical grassy biome and support the livelihoods of millions of rural and urban people. Charcoal production in particular is a major economic activity, but its impact on other ecosystem services is little studied. To address this, our study collected biophysical and social datasets, which were combined in ecological production functions, to assess ecosystem service provision and its change under different charcoal production scenarios in Gaza Province, southern Mozambique. We found that villages with longer histories of charcoal production had experienced declines in wood suitable for charcoal, firewood and construction, and tended to have lower perceived availabilities of these services. Scenarios of future charcoal impacts indicated that firewood and woody construction services were likely to trade-off with charcoal production. However, even under the most extreme charcoal scenario, these services were not completely lost. Other provisioning services, such as wild food, medicinal plants and grass, were largely unaffected by charcoal production. To reduce the future impacts of charcoal production, producers must avoid increased intensification of charcoal extraction by avoiding the expansion of species and sizes of trees used for charcoal production. This is a major challenge to land managers and policymakers in the area.This article is part of the themed issue ‘Tropical grassy biomes: linking ecology, human use and conservation’. 相似文献
32.
Caroline de Souza Barros Valeria Garrido Vanessa Melchiades Rafaela Gomes Max Willian Lisboa Gomes Valeria Laneuville Teixeira Izabel Christina Nunes de Palmer Paixão 《Journal of applied phycology》2017,29(2):769-773
Studies with diterpenes from marine brown alga Canistrocarpus cervicornis showed the antiviral potential of the products from this alga in controlling the replication of HSV-1 and maintaining low cytotoxicity. Hence, the aim of this work was to evaluate the anti-herpetic efficacy of C. cervicornis extract ointment in BALB/c mice. To test the anti-herpetic efficacy in vivo, four groups of BALB/c mice (n?=?5) were used: 1—untreated, 2—extract ointment (2 % or 0.4 mg cm?2 dose?1), 3—Acyclovir cream (5 % or 1.0 mg cm?2 dose?1), and 4—ointment base. The right midflank of each mouse was clipped and depilated with a chemical depilatory. After 2 days, the skin area was scratched and inoculated with HSV-1. The ointments and cream were applied three times a day over a 16-day period, beginning 1 h after virus inoculation. The development of skin lesions was continuously monitored and scored. To evaluate the effect of C. cervicornis topical treatment on biochemical parameters and on body weight, two uninfected groups were formed: an untreated group and a group treated with ointment C. cervicornis extract (2 %). The signs of infection appeared from the second day after infection, while on the 10th day of the experiment, the ointment base and untreated groups had significantly more severe lesions than did the groups that were treated with extract (p?<?0.05) or acyclovir (p?<?0,01). The topical application of extract ointment did not change body weight, hepatic, or renal function suggesting that the extract has a low toxicity in this route of administration. These results suggest that the extract may be useful in reducing the severity of HSV-1 cutaneous lesions. 相似文献
33.
Louise Pierneef Anouk van Hooij Anneke Taal Raisa Rumbaut Mauricio Lisboa Nobre Wim van Brakel Annemieke Geluk 《PLoS neglected tropical diseases》2021,15(8)
BackgroundLeprosy elimination primarily targets transmission of Mycobacterium leprae which is not restricted to patients’ households. As interruption of transmission is imminent in many countries, a test to detect infected asymptomatic individuals who can perpetuate transmission is required. Antibodies directed against M. leprae antigens are indicative of M. leprae infection but cannot discriminate between active and past infection. Seroprevalence in young children, however, reflects recent M. leprae infection and may thus be used to monitor transmission in an area. Therefore, this literature review aimed to evaluate what has been reported on serological tests measuring anti-M. leprae antibodies in children without leprosy below the age of 15 in leprosy-endemic areas.Methods and findingsA literature search was performed in the databases Pubmed, Infolep, Web of Science and The Virtual Health Library. From the 724 articles identified through the search criteria, 28 full-text articles fulfilled all inclusion criteria. Two additional papers were identified through snowballing, resulting in a total of 30 articles reporting data from ten countries. All serological tests measured antibodies against phenolic glycolipid-I or synthetic derivatives thereof, either quantitatively (ELISA or UCP-LFA) or qualitatively (ML-flow or NDO-LID rapid test). The median seroprevalence in children in endemic areas was 14.9% and was stable over time if disease incidence remained unchanged. Importantly, seroprevalence decreased with age, indicating that children are a suitable group for sensitive assessment of recent M. leprae infection. However, direct comparison between areas, solely based on the data reported in these studies, was impeded by the use of different tests and variable cut-off levels.ConclusionsQuantitative anti-PGL-I serology in young children holds promise as a screening test to assess M. leprae infection and may be applied as a proxy for transmission and thereby as a means to monitor the effect of (prophylactic) interventions on the route to leprosy elimination. 相似文献
34.
Rodolfo Assis Lisboa Felipe Assis Lisboa Guilherme de Castro Santos Marcus Vinícius Melo Andrade José Renan Cunha-Melo 《In vitro cellular & developmental biology. Animal》2009,45(10):614-621
Orthodontic force compresses the periodontal ligament promoting the expression of pro-inflammatory mediators and matrix metalloproteinases
responsible for tooth movement. The extent in time while periodontal cells are being treated and the increment in the amount
of mechanical stress caused by the orthodontic force is thought to regulate the levels of metalloproteinases in the periodontal
tissue. To study the possible regulation in the activity of metalloproteinases 2, 3, 7, 9, and 10 by simulated orthodontic
force, human periodontal ligament fibroblast cultures were centrifuged (141×g) for 30, 60, 90, and 120 min, simulating the orthodontic force. Cell viability, protein quantification, and activity of metalloproteinases
by zymography were evaluated at 24, 48, and 72 h after centrifugation in both cell lysates and growth medium. The activity
of the 72-kDa matrix metalloproteinase 2 was decreased at 24 h regardless of the duration of centrifugation and at 48 h in
cells centrifuged for 30 min only. Decrease in the amount of total protein in lysates was seen at 48 and 72 h with no change
in cell viability. The data seem to indicate that the amount of mechanical stress regulates the levels of secreted matrix
metalloproteinase 2. In addition, the centrifugation as a model for simulated orthodontic force may be used as a simple and
reliable method to study the role played by matrix metalloproteinases in periodontal ligament when submitted to mechanical
force as occurring during tooth movement. 相似文献
35.
Adrian Egli Deanna M. Santer Daire O'Shea Khaled Barakat Mohammedyaseen Syedbasha Madeleine Vollmer Aliyah Baluch Rakesh Bhat Jody Groenendyk Michael A. Joyce Luiz F. Lisboa Brad S. Thomas Manuel Battegay Nina Khanna Thomas Mueller D. Lorne J. Tyrrell Michael Houghton Atul Humar Deepali Kumar 《PLoS pathogens》2014,10(12)
Influenza is a major cause of morbidity and mortality in immunosuppressed persons, and vaccination often confers insufficient protection. IL-28B, a member of the interferon (IFN)-λ family, has variable expression due to single nucleotide polymorphisms (SNPs). While type-I IFNs are well known to modulate adaptive immunity, the impact of IL-28B on B- and T-cell vaccine responses is unclear. Here we demonstrate that the presence of the IL-28B TG/GG genotype (rs8099917, minor-allele) was associated with increased seroconversion following influenza vaccination (OR 1.99 p = 0.038). Also, influenza A (H1N1)-stimulated T- and B-cells from minor-allele carriers showed increased IL-4 production (4-fold) and HLA-DR expression, respectively. In vitro, recombinant IL-28B increased Th1-cytokines (e.g. IFN-γ), and suppressed Th2-cytokines (e.g. IL-4, IL-5, and IL-13), H1N1-stimulated B-cell proliferation (reduced 70%), and IgG-production (reduced>70%). Since IL-28B inhibited B-cell responses, we designed antagonistic peptides to block the IL-28 receptor α-subunit (IL28RA). In vitro, these peptides significantly suppressed binding of IFN-λs to IL28RA, increased H1N1-stimulated B-cell activation and IgG-production in samples from healthy volunteers (2-fold) and from transplant patients previously unresponsive to vaccination (1.4-fold). Together, these findings identify IL-28B as a key regulator of the Th1/Th2 balance during influenza vaccination. Blockade of IL28RA offers a novel strategy to augment vaccine responses. 相似文献
36.
Ana Maria B. Menezes Rogelio Pérez-Padilla Fernando César Wehrmeister Maria Victorina Lopez-Varela Adriana Mui?o Gonzalo Valdivia Carmen Lisboa José Roberto B. Jardim Maria Montes de Oca Carlos Talamo Renata Bielemann Mariana Gazzotti Ruy Laurenti Bartolomé Celli Cesar G. Victora for the PLATINO team 《PloS one》2014,9(10)
Objective
To determine whether the presence of chronic obstructive lung disease (COPD) and reduction of lung function parameters were predictors of mortality in a cohort.Materials/Patients and Methods
Population based cohorts were followed in Montevideo, Santiago and Sao Paulo during 5, 6 and 9 years, respectively. Outcomes included all-cause, cardiovascular, respiratory and cancer mortality; exposures were COPD, forced expiratory volume in one second (FEV1) and forced vital capacity (FVC). Cox regression was used for analyses. Sensitivity, specificity, positive and negative predictive values, receiver operator characteristics curves and Youden''s index were calculated.Results
Main causes of death were cardiovascular, respiratory and cancer. Baseline COPD was associated with overall mortality (HR = 1.43 for FEV1/FVC<LLN; 2.01 for GOLD 2-4; 1.46 for GOLD 1-4; 1.50 for FEV1/FEV6 <LLN). For cardiovascular mortality, significant associations were found with GOLD 2-4 (HR = 2.68) and with GOLD 1-4 (HR = 1.78) for both genders together (not among women). Low FEV1 was risk for overall and respiratory mortality (both genders combined). FVC was not associated with overall mortality. For most COPD criteria sensitivity was low and specificity high. The area under the curve for FEV1 was greater than for FVC for overall and cardiovascular mortality.Answer to the Question
COPD and low FEV1 are important predictors for overall and cardiovascular mortality in Latin America. 相似文献37.
Carolina C. Lisboa Richard T. Conant Michelle L. Haddix Carlos Eduardo P. Cerri Carlos C. Cerri 《Ecosystems》2009,12(7):1212-1221
The effect of conversion from forest-to-pasture upon soil carbon stocks has been intensively discussed, but few studies focus
on how this land-use change affects carbon (C) distribution across soil fractions in the Amazon basin. We investigated this
in the 20 cm depth along a chronosequence of sites from native forest to three successively older pastures. We performed a
physicochemical fractionation of bulk soil samples to better understand the mechanisms by which soil C is stabilized and evaluate
the contribution of each C fraction to total soil C. Additionally, we used a two-pool model to estimate the mean residence
time (MRT) for the slow and active pool C in each fraction. Soil C increased with conversion from forest-to-pasture in the
particulate organic matter (>250 μm), microaggregate (53–250 μm), and d-clay (<2 μm) fractions. The microaggregate comprised
the highest soil C content after the conversion from forest-to-pasture. The C content of the d-silt fraction decreased with
time since conversion to pasture. Forest-derived C remained in all fractions with the highest concentration in the finest
fractions, with the largest proportion of forest-derived soil C associated with clay minerals. Results from this work indicate
that microaggregate formation is sensitive to changes in management and might serve as an indicator for management-induced
soil carbon changes, and the soil C changes in the fractions are dependent on soil texture. 相似文献
38.
Aleksandra do Socorro da Silva Silvana Rossy de Brito Nandamudi Lankalapalli Vijaykumar Cláudio Alex Jorge da Rocha Maurílio de Abreu Monteiro Jo?o Crisóstomo Weyl Albuquerque Costa Carlos Renato Lisboa Francês 《PloS one》2016,11(1)
The published literature reveals several arguments concerning the strategic importance of information and communication technology (ICT) interventions for developing countries where the digital divide is a challenge. Large-scale ICT interventions can be an option for countries whose regions, both urban and rural, present a high number of digitally excluded people. Our goal was to monitor and identify problems in interventions aimed at certification for a large number of participants in different geographical regions. Our case study is the training at the Telecentros.BR, a program created in Brazil to install telecenters and certify individuals to use ICT resources. We propose an approach that applies social network analysis and mining techniques to data collected from Telecentros.BR dataset and from the socioeconomics and telecommunications infrastructure indicators of the participants’ municipalities. We found that (i) the analysis of interactions in different time periods reflects the objectives of each phase of training, highlighting the increased density in the phase in which participants develop and disseminate their projects; (ii) analysis according to the roles of participants (i.e., tutors or community members) reveals that the interactions were influenced by the center (or region) to which the participant belongs (that is, a community contained mainly members of the same region and always with the presence of tutors, contradicting expectations of the training project, which aimed for intense collaboration of the participants, regardless of the geographic region); (iii) the social network of participants influences the success of the training: that is, given evidence that the degree of the community member is in the highest range, the probability of this individual concluding the training is 0.689; (iv) the North region presented the lowest probability of participant certification, whereas the Northeast, which served municipalities with similar characteristics, presented high probability of certification, associated with the highest degree in social networking platform. 相似文献
39.
40.