首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   36篇
  免费   2篇
  2022年   1篇
  2021年   6篇
  2020年   1篇
  2019年   1篇
  2018年   3篇
  2017年   3篇
  2016年   1篇
  2015年   2篇
  2013年   1篇
  2012年   5篇
  2011年   2篇
  2010年   2篇
  2009年   1篇
  2008年   2篇
  2007年   1篇
  2006年   1篇
  2005年   1篇
  2004年   1篇
  2003年   1篇
  1996年   1篇
  1995年   1篇
排序方式: 共有38条查询结果,搜索用时 15 毫秒
21.
Chemical insecticides released into the environment may have adverse biological effects. Therefore, there is a need for ecofriendly insecticides for mosquito control. Xerophytic plant extracts that may provide more ecofriendly active component were evaluated against Culex pipiens 4th instars. Plant extracts prepared using different solvents with a Soxhlet apparatus and different concentrations were tested against Culex pipiens larvae. The effects were observed at 24 h and 72 h intervals and LD50 and LD90 values determined. Chloroform (CHCl3) and ethyl acetate (EtOAc) extracts of Althaea ludwigii were the most effective against Cx. pipiens 4th instars, but were highly dependent on extract concentrations and exposure time. Results suggest that A. ludwigii extracts contain bioactive compounds, such as phenols and saponins, that may provide effective Cx. pipiens larval control. However, the extract was found to be toxic to zebrafish larvae, and may be toxic to other aquatic fauna. Further studies to determine the active components and toxicity to other fauna are needed.  相似文献   
22.

Introduction

Ultrasound examination coupled with fine-needle aspiration (FNA) cytology is the gold standard for the diagnosis of thyroid cancer. However, about 10–40% of these analyses cannot be conclusive on the malignancy of the lesions and lead to surgery. The cytological indeterminate FNA biopsies are mainly constituted of follicular—patterned lesions, which are benign in 80% of the cases.

Objectives

The development of a FNAB classification approach based on the metabolic phenotype of the lesions, complementary to cytology and other molecular tests in order to limit the number of patients undergoing unnecessary thyroidectomy.

Methods

We explored the potential of a NMR-based metabolomics approach to improve the quality of the diagnosis from FNABs, using thyroid tissues collected post-surgically.

Results

The NMR-detected metabolites were used to produce a robust OPLSDA model to discriminate between benign and malignant tumours. Malignancy was correlated with amino acids such as tyrosine, serine, alanine, leucine and phenylalanine and anti-correlated with myo-inositol, scyllo-inositol and citrate. Diagnosis accuracy was of 84.8% when only indeterminate lesions were considered.

Conclusion

These results on model FNAB indicate that there is a clear interest in exploring the possibility to export NMR metabolomics to pre-surgical diagnostics.
  相似文献   
23.
The study of the interplay between speciation and hybridization is of primary importance in evolutionary biology. Octocorals are ecologically important species whose shallow phylogenetic relationships often remain to be studied. In the Mediterranean Sea, three congeneric octocorals can be observed in sympatry: Eunicella verrucosa, Eunicella cavolini and Eunicella singularis. They display morphological differences and E. singularis hosts photosynthetic Symbiodinium, contrary to the two other species. Two nuclear sequence markers were used to study speciation and gene flow between these species, through network analysis and Approximate Bayesian Computation (ABC). Shared sequences indicated the possibility of hybridization or incomplete lineage sorting. According to ABC, a scenario of gene flow through secondary contact was the best model to explain these results. At the intraspecific level, neither geographical nor ecological isolation corresponded to distinct genetic lineages in E. cavolini. These results are discussed in the light of the potential role of ecology and genetic incompatibilities in the persistence of species limits.  相似文献   
24.

Background

Media plays a vital role in shaping public policies and opinions through disseminating health-related information. This study aims at exploring the role of media in informing health policies in Lebanon, identifying the factors influencing health reporting and investigating the role of evidence in health journalism and the quality of health reporting. It also identifies strategies to enhance the use of evidence in health journalism and improve the quality of health reporting.

Methods

Media analysis was conducted to assess the way media reports on health-related issues and the quality of reporting using a quality assessment tool. Semi-structured interviews were also conducted with 27 journalists, researchers and policymakers to explore their perception on the role of media in health policymaking and the factors influencing health reporting. In addition, a validation workshop was conducted.

Results

Out of 1,279 health-related news articles identified, 318 articles used certain type of evidence to report health issues 39.8% of which relied on experts’ opinions as their source of evidence while only 5.9% referenced peer-reviewed research studies. The quality of health reporting was judged to be low based on a quality assessment tool consisting of a set of ten criteria. Journalists raised concerns about issues impeding them from referring to evidence. Journalists also reported difficulties with the investigative health journalism. Policymakers and researchers viewed media as an important tool for evidence-informed health policies, however, serious concerns were voiced in terms of the current practice and capacities.

Conclusion

Our study provides a structured reflection on the role of media and the factors that influence health reporting including context-specific strategies that would enhance the quality and promote the use of evidence in health reporting. In the light of the political changes in many Middle Eastern countries, findings from this study can contribute to redefining the role of media in strengthening health systems.  相似文献   
25.
26.
BackgroundPrevious studies reported the efficacy of the implementation of information technology in clinical evaluation. No research has addressed the development of mobile applications for the clinical evaluation and diagnosis of paediatric language disorders.PurposeThis study aims to investigate the usability of a clinical assessment mobile application (app) prototype, the “Paediatric Arabic Language Test” (PALT), to diagnose language disorders among paediatric patients.MethodsUsing the Lewis Computer Software Usability Questionnaire (CSUQ) and a 5-point Likert Scale, data was collected and scored on the usability of the app prototype developed on two mobile platforms- iPhone and iPad- across a general operating system, iOS. A sample of 77 potential end-users rated the usability of the app prototype that they used between 2017 and 2019.ResultsThe average CSUQ rating for the app prototype was 75.68 and 53.2% strongly agreed that the information and its organization was clear and easy to understand; 75% of the end users were very satisfied (p < 0.0001). Out of the total items, 68% of studied items on the scale loaded on factor 1 even after subjecting the scale to three standardization methods.ConclusionThe prototype design was judged to be usable. Users reported an effective user interface that allows effective operation. Differences in the factor loading may be explained by cultural factors, type of task and field context.  相似文献   
27.

Goal, Scope and Background

Photochemical ozone creation potentials (POCPs) typically used in life cycle impact assessment (LCIA) to address the impact category ‘photo-oxidant formation’ only provide factors for particular volatile organic compounds and do not take into account background concentrations and meteorological conditions. However, the formation of ozone from volatile organic compounds (VOCs), carbon monoxide (CO) and nitrogen oxides (NOx) is highly dependent on the background pollutant concentrations and meteorological conditions. Some LCIA manuals therefore recommend working with potentials for high background concentrations of NOx (Derwent 1998), and potentials for low background concentrations of NOx (Andersson-Sköld 1992).

Objectives

This study has introduced an improved set of POCPs independently of meteorological and emission conditions specific to a given period or location. Whereas current POCP values may be relevant to estimate the photo-oxidant formation over a certain (temporally and spatially well-defined) domain, this study has further introduced more relevant values with respect to potential impacts of ozone on human health and environment.

Methods

For the computation of POCP values on the scale of Western Europe, independently of meteorological and emission conditions specific to a given period or location, a Eulerian chemistry-transport numerical model (CHIMERE-continental) has been implemented over three summer seasons. POCPs have been evaluated for ten VOC species (including the whole VOC group), CO and NOx. The coherence of this new set of POCP values with previous studies has been checked. The spatial representa-tivity of POCP values over the simulation domain in Europe has also been addressed. The robustness of these POCP values to changes in the implemented chemical mechanism used in our model has been checked.

Results and Discussion

The POCPs computed in this study were generally lower than the POCPs calculated in previous studies. In the previous studies, but not here, the POCPs have been calculated with particular meteorological conditions (during anti-cyclonic, fair weather conditions) or emission levels (high polluted backgrounds) known to be optimal with respect to ozone formation. Despite the quantitative variations in the POCP values, we have found a good agreement in the relative ranking of the pollutant species between this study and previous studies. It was also shown that POCP values display significant spatial variability over Western Europe (the largest spatial differences were obtained for NOx where the sign of the POCP value even changes from region to region).

Conclusions

Finally, the temporally and spatially averaged values obtained here for the POCP index update previous values and represent an attempt to generate the most appropriate and accurate scale for European conditions independently of meteorological and emission conditions specific to a given period or location.

Recommendations and Outlook

These new PCOPs should be useful to LCIA-practitioners in further life cycle impact assessment. However, for the NOx species, we do not recommend the use of the POCP value for LCIA.
  相似文献   
28.
We have shown previously that caspases were specifically involved in the differentiation of peripheral blood monocytes into macrophages while not required for monocyte differentiation into dendritic cells. To identify caspase targets in monocytes undergoing macrophagic differentiation, we used the human monocytic leukemic cell line U937, whose macrophagic differentiation induced by exposure to 12-O-tetradecanoylphorbol 13-acetate (TPA) can be prevented by expression of the baculovirus caspase-inhibitory protein p35. A comparative two-dimensional gel proteomic analysis of empty vector- and p35-transfected cells after 12 h of exposure to 20 nm TPA, followed by mass spectrometry analysis, identified 38 differentially expressed proteins. Those overexpressed in p35-expressing cells (n = 16) were all full-length, whereas half of those overexpressed in control cells (n = 22) were N- or C-terminal cleavage fragments. The cleavage or degradation of seven of these proteins was confirmed in peripheral blood monocytes undergoing macrophage colony-stimulating factor-induced macrophagic differentiation. In U937 cells exposed to TPA, these proteolytic events can be inhibited by expression of a caspase-8 dominant negative mutant or the cowpox virus CrmA caspase inhibitor. These cleavages provide new insights to analyze the role of caspases in this specific differentiation program.  相似文献   
29.
The objective of this study was to evaluate associations between adverse outcomes in twin pregnancies and preterm prelabour rupture of membranes (PPROM). A chart review of 246 consecutive twin pregnancies with confirmed PPROM was conducted. Regression analysis (beta [natural log of the odds ratio] and odds ratio [OR]) was performed to identify independent predictors. Two hundred and forty-six twin pregnancies, 492 liveborns, and 20 neonatal deaths. Mean (SD) PPROM gestational age (GA): 31.3 (3.8) wk; delivery GA: 32.0 (3.3) wk. PPROM < 30 wk was associated with increased parity (OR: 2.66), and log (admission leukocyte count) (OR: 9.99). Shortened latency was associated with PPROM GA (beta = -0.17) and chorioamnionitis (beta = 0.95). Neonatal sepsis was predicted by lower delivery GA (OR: 2.04). Adverse perinatal outcomes were protected against by older GA at PPROM (OR 0.53) and shortened latency (OR 0.73). It was concluded that increased leukocytosis and parity implies an infectious aetiology in earlier PPROM. Increased risk for neonatal sepsis at earlier delivery GA is consistent with gestation-dependent fetal immunocompetence. Early PPROM and long latencies were associated with increased adverse perinatal outcomes.  相似文献   
30.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号