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   79篇
  免费   3篇
  国内免费   1篇
  2021年   2篇
  2020年   1篇
  2018年   3篇
  2017年   4篇
  2016年   3篇
  2015年   3篇
  2014年   2篇
  2013年   6篇
  2012年   6篇
  2011年   4篇
  2010年   8篇
  2009年   7篇
  2008年   3篇
  2007年   4篇
  2006年   6篇
  2005年   1篇
  2004年   1篇
  2003年   1篇
  2002年   1篇
  2001年   1篇
  2000年   2篇
  1999年   1篇
  1998年   3篇
  1997年   1篇
  1996年   1篇
  1995年   1篇
  1994年   2篇
  1990年   1篇
  1988年   1篇
  1983年   1篇
  1982年   1篇
  1977年   1篇
排序方式: 共有83条查询结果,搜索用时 31 毫秒
31.

Fusarium wilt and root-knot are important diseases of tomato. The use of chemical is becoming less appealing because of the health implications. Also, the chemicals required are often not within the reach of farmers in most of the developing part of the world. This research is aimed at finding an alternative mode of control. Tomato variety Roma VF inoculated with Meloidogyne and Fusarium were treated with 2 g/kg soil neem seed powder in the screenhouse and 2 Mg ha ? 1 in the field. An untreated and Furadan treated plot in the field served as control. Neem seed powder significantly reduced the disease severity of Fusarium and root-knot in both screenhouse and field. Results suggest the possible use of neem seed powder for control of the root-knot nematodes - Fusarium wilt disease complex.  相似文献   
32.

Background

Chikungunya virus (CHIKV) is an emerging mosquito-borne alphavirus that has caused multiple unprecedented and re-emerging outbreaks in both tropical and temperate countries. Despite ongoing research efforts, the underlying factors involved in facilitating CHIKV replication during early infection remains ill-characterized. The present study serves to identify host proteins modulated in response to early CHIKV infection using a proteomics approach.

Methodology and Principal Findings

The whole cell proteome profiles of CHIKV-infected and mock control WRL-68 cells were compared and analyzed using two-dimensional gel electrophoresis (2-DGE). Fifty-three spots were found to be differentially modulated and 50 were successfully identified by MALDI-TOF/TOF. Eight were significantly up-regulated and 42 were down-regulated. The mRNA expressions of 15 genes were also found to correlate with the corresponding protein expression. STRING network analysis identified several biological processes to be affected, including mRNA processing, translation, energy production and cellular metabolism, ubiquitin-proteasome pathway (UPP) and cell cycle regulation.

Conclusion/Significance

This study constitutes a first attempt to investigate alteration of the host cellular proteome during early CHIKV infection. Our proteomics data showed that during early infection, CHIKV affected the expression of proteins that are involved in mRNA processing, host metabolic machinery, UPP, and cyclin-dependent kinase 1 (CDK1) regulation (in favour of virus survival, replication and transmission). While results from this study complement the proteomics results obtained from previous late host response studies, functional characterization of these proteins is warranted to reinforce our understanding of their roles during early CHIKV infection in humans.  相似文献   
33.

Background

Missed or inappropriate hospital appointments cost the UK National Health Service millions of pounds each year and delay treatment for other patients. Innovative methods of appointment scheduling that are more flexible to patient needs, may improve service quality and preserve resources.

Methods

A systematic review of the evidence for the clinical effectiveness of patient initiated clinics in managing long term care for people with chronic or recurrent conditions in secondary care. Seven databases were searched including MEDLINE, Embase and PsycINFO (using the OVID interface), the Cochrane Library of Systematic Reviews and CENTRAL, Science Citation Index Expanded, Social Sciences Citation Index, and Conference Proceedings Citation Index (via the Web of Science interface) from inception to June 2013. Studies comparing patient initiated clinics with traditional consultant-led clinics in secondary care for people with long term chronic or recurrent diseases were included. Included studies had to provide data on clinical or resource use outcomes. Data were extracted and checked by two reviewers using a piloted, standardised data extraction form.

Results

Eight studies (n = 1927 individuals) were included. All were conducted in the UK. There were few significant differences in clinical outcomes between the intervention and control groups. In some instances, using the patient initiated clinics model was associated with savings in time and resource use. The risk of harm from using the patient initiated clinic model of organising outpatient care is low. Studies with longer follow-up periods are needed to assess the long term costs and the ongoing risk of potential harms.

Conclusions

The UK policy context is ripe for evidence-based, patient-centred services to be implemented, especially where the use of health care resources can be optimised without reducing the quality of care. Implementation of patient initiated clinics should remain cautious, with importance placed on ongoing evaluation of long term outcomes and costs.  相似文献   
34.
MitoQ(10) is a ubiquinone that accumulates within mitochondria driven by a conjugated lipophilic triphenylphosphonium cation (TPP(+)). Once there, MitoQ(10) is reduced to its active ubiquinol form, which has been used to prevent mitochondrial oxidative damage and to infer the involvement of reactive oxygen species in signaling pathways. Here we show MitoQ(10) is effectively reduced by complex II, but is a poor substrate for complex I, complex III, and electron-transferring flavoprotein (ETF):quinone oxidoreductase (ETF-QOR). This differential reactivity could be explained if the bulky TPP(+) moiety sterically hindered access of the ubiquinone group to enzyme active sites with a long, narrow access channel. Using a combination of molecular modeling and an uncharged analog of MitoQ(10) with similar sterics (tritylQ(10)), we infer that the interaction of MitoQ(10) with complex I and ETF-QOR, but not complex III, is inhibited by its bulky TPP(+) moiety. To explain its lack of reactivity with complex III we show that the TPP(+) moiety of MitoQ(10) is ineffective at quenching pyrene fluorophors deeply buried within phospholipid bilayers and thus is positioned near the membrane surface. This superficial position of the TPP(+) moiety, as well as the low solubility of MitoQ(10) in non-polar organic solvents, suggests that the concentration of the entire MitoQ(10) molecule in the membrane core is very limited. As overlaying MitoQ(10) onto the structure of complex III indicates that MitoQ(10) cannot react with complex III without its TPP(+) moiety entering the low dielectric of the membrane core, we conclude that the TPP(+) moiety does anchor the tethered ubiquinol group out of reach of the active site(s) of complex III, thus explaining its slow oxidation. In contrast the ubiquinone moiety of MitoQ(10) is able to quench fluorophors deep within the membrane core, indicating a high concentration of the ubiquinone moiety within the membrane and explaining its good anti-oxidant efficacy. These findings will facilitate the rational design of future mitochondria-targeted molecules.  相似文献   
35.
Context: Genotoxicity assays are widely employed in human biomonitoring studies to assess genetic damage inflicted by genotoxic agents.

Objective: Evaluation of micronuclei (MN) as a screening marker of occupational ionizing radiation (IR) exposure.

Materials and methods: Using micronucleus test, peripheral blood lymphocytes (PBL) of 402 control and exposed subjects were screened for genetic damage.

Results: The mean frequencies of micronucleus test parameters were significantly higher in exposed persons. Increase of micronucleus yield with duration of exposure (DOE) by 0.303MN/year was revealed.

Discussion and conclusion: The obtained data encourage us to consider MN as valuable markers for preventive medical screening of occupationally exposed groups.  相似文献   

36.
The phylogenetic potential of entire 26S rDNA sequences in plants   总被引:6,自引:1,他引:5  
18S ribosomal RNA genes are the most widely used nuclear sequences for phylogeny reconstruction at higher taxonomic levels in plants. However, due to a conservative rate of evolution, 18S rDNA alone sometimes provides too few phylogenetically informative characters to resolve relationships adequately. Previous studies using partial sequences have suggested the potential of 26S or large-subunit (LSU) rDNA for phylogeny retrieval at taxonomic levels comparable to those investigated with 18S rDNA. Here we explore the patterns of molecular evolution of entire 26S rDNA sequences and their impact on phylogeny retrieval. We present a protocol for PCR amplification and sequencing of entire (approximately 3.4 kb) 26S rDNA sequences as single amplicons, as well as primers that can be used for amplification and sequencing. These primers proved useful in angiosperms and Gnetales and likely have broader applicability. With these protocols and primers, entire 26S rDNA sequences were generated for a diverse array of 15 seed plants, including basal eudicots, monocots, and higher eudicots, plus two representatives of Gnetales. Comparisons of sequence dissimilarity indicate that expansion segments (or divergence domains) evolve 6.4 to 10.2 times as fast as conserved core regions of 26S rDNA sequences in plants. Additional comparisons indicate that 26S rDNA evolves 1.6 to 2.2 times as fast as and provides 3.3 times as many phylogenetically informative characters as 18S rDNA; compared to the chloroplast gene rbcL, 26S rDNA evolves at 0.44 to 1.0 times its rate and provides 2.0 times as many phylogenetically informative characters. Expansion segment sequences analyzed here evolve 1.2 to 3.0 times faster than rbcL, providing 1.5 times the number of informative characters. Plant expansion segments have a pattern of evolution distinct from that found in animals, exhibiting less cryptic sequence simplicity, a lower frequency of insertion and deletion, and greater phylogenetic potential.   相似文献   
37.
38.
The mitochondria-targeted antioxidant MitoQ comprises a ubiquinol moiety covalently attached through an aliphatic carbon chain to the lipophilic triphenylphosphonium cation. This cation drives the membrane potential-dependent accumulation of MitoQ into mitochondria, enabling the ubiquinol antioxidant to prevent mitochondrial oxidative damage far more effectively than untargeted antioxidants. We sought to fine-tune the hydrophobicity of MitoQ so as to control the extent of its membrane binding and penetration into the phospholipid bilayer, and thereby regulate its partitioning between the membrane and aqueous phases within mitochondria and cells. To do this, MitoQ variants with 3, 5, 10 and 15 carbon aliphatic chains were synthesised. These molecules had a wide range of hydrophobicities with octan-1-ol/phosphate buffered saline partition coefficients from 2.8 to 20000. All MitoQ variants were accumulated into mitochondria driven by the membrane potential, but their binding to phospholipid bilayers varied from negligible for MitoQ3 to essentially total for MitoQ15. Despite the span of hydrophobicites, all MitoQ variants were effective antioxidants. Therefore, it is possible to fine-tune the degree of membrane association of MitoQ and other mitochondria targeted compounds, without losing antioxidant efficacy. This indicates how the uptake and distribution of mitochondria-targeted compounds within mitochondria and cells can be controlled, thereby facilitating investigations of mitochondrial oxidative damage.  相似文献   
39.
The DNA sequences of the Adh genes of three members of the Drosophila melanogaster species subgroup have been determined. This completes the Adh sequences of the eight species of this subgroup. Two species, D. yakuba and D. teissieri, possess processed Adh pseudogenes. In all of the species of the subgroup, a gene of unknown function, Adhr, is located about 300 bp 3' to Adh. Although this gene is experiencing a higher rate of synonymous substitution than Adh, it is more constrained at the amino acid level. Phylogenetic relationships between all eight members of the melanogaster subgroup have been analyzed using a variety of methods. All analyses suggested that the D. yakuba and D. teissieri pseudogenes have a single common ancestor, rather than evolving independently in each species, and that D. melanogaster is the sister species to D. simulans, D. sechellia, and D. mauritiana. The evolutionary relationships of the latter three species remain equivocal.   相似文献   
40.
Summary Larvae ofToxocara canis were developed and stored at different temperatures for different periods of time at 70 to 80% relative humidity. After 18 months the infectivity of these larvae was tested byin vitro hatching and by the use of white mice (in vivo infection). Although the larvae were stored for very long periods, there was no indication that they were weaker than the control sample. After a further 7 months, when part of the original sample was exposed to higher temperatures (35 to 41°C), a high proportion of them (70%) hatched spontaneously and died, but the larvae of the remaining 30% were still viable and active and forming a source of danger to the community.
Resumen Larvas deToxocora canis se desarrollaron y guardaron a differentes temperaturas durante distintos periodos de tiempo a 70–80% de humedad relativa. Alos 18 meses se probó la infectividad de dichas larvasin vitro y utilizando ratones blancos (infecciónin vivo). Aunque las larvas se hubieran almacenado durante largos periodos no se observó que fueran más débiles que la muestra control. Pasados otros 7 meses, cuando parte de la muestra original se expuso a temperaturas más elevadas (35 a 41°C) gran parte de las larvas (70%) eclosionaron espontaneamente y murieron, sin embargo las larvas restantes (30%) siguieron viables y activas representando una fuente de peligro para la comunidad.

Résumé On a développé des larves deToxocara canis et on les a conservées à différentes températures pendant différents temps à une humidité relative de 70 à 80%. Après 18 mois, le pouvoir infectieux de ces larves a été testé par incubationin vitro et à l'aide de la souris blanche (infectionin vivo). Bien que les larves aient été conservées pour de longues périodes, il n'y a eu aucune indication de ce qu'elles étaient plus faibles que celles de l'échantillon de contrôle. Après 7 mois supplémentaires, alor qu'une partie de l'échantillon de départ était exposé à des températures plus élevées (37 à 41°C), une proportion élevée de ces larves (70%) a éclos spontanément et en est morte, mais les 30% restant étaient toujours viables et actifs, formant ainsi une source de danger pour la communauté.
  相似文献   
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