全文获取类型
收费全文 | 214篇 |
免费 | 19篇 |
出版年
2022年 | 2篇 |
2021年 | 3篇 |
2020年 | 2篇 |
2019年 | 2篇 |
2018年 | 5篇 |
2017年 | 4篇 |
2016年 | 11篇 |
2015年 | 9篇 |
2014年 | 11篇 |
2013年 | 22篇 |
2012年 | 16篇 |
2011年 | 20篇 |
2010年 | 20篇 |
2009年 | 13篇 |
2008年 | 15篇 |
2007年 | 19篇 |
2006年 | 11篇 |
2005年 | 11篇 |
2004年 | 6篇 |
2003年 | 8篇 |
2002年 | 4篇 |
2001年 | 3篇 |
2000年 | 1篇 |
1999年 | 1篇 |
1998年 | 1篇 |
1997年 | 4篇 |
1996年 | 1篇 |
1994年 | 1篇 |
1992年 | 2篇 |
1991年 | 1篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1981年 | 1篇 |
1977年 | 1篇 |
排序方式: 共有233条查询结果,搜索用时 421 毫秒
91.
T Bousema RR Dinglasan I Morlais LC Gouagna T van Warmerdam PH Awono-Ambene S Bonnet M Diallo M Coulibaly T Tchuinkam B Mulder G Targett C Drakeley C Sutherland V Robert O Doumbo Y Touré PM Graves W Roeffen R Sauerwein A Birkett E Locke M Morin Y Wu TS Churcher 《PloS one》2012,7(8):e42821
Introduction
In the era of malaria elimination and eradication, drug-based and vaccine-based approaches to reduce malaria transmission are receiving greater attention. Such interventions require assays that reliably measure the transmission of Plasmodium from humans to Anopheles mosquitoes.Methods
We compared two commonly used mosquito feeding assay procedures: direct skin feeding assays and membrane feeding assays. Three conditions under which membrane feeding assays are performed were examined: assays with i) whole blood, ii) blood pellets resuspended with autologous plasma of the gametocyte carrier, and iii) blood pellets resuspended with heterologous control serum.Results
930 transmission experiments from Cameroon, The Gambia, Mali and Senegal were included in the analyses. Direct skin feeding assays resulted in higher mosquito infection rates compared to membrane feeding assays (odds ratio 2.39, 95% confidence interval 1.94–2.95) with evident heterogeneity between studies. Mosquito infection rates in membrane feeding assays and direct skin feeding assays were strongly correlated (p<0.0001). Replacing the plasma of the gametocyte donor with malaria naïve control serum resulted in higher mosquito infection rates compared to own plasma (OR 1.92, 95% CI 1.68–2.19) while the infectiousness of gametocytes may be reduced during the replacement procedure (OR 0.60, 95% CI 0.52–0.70).Conclusions
Despite a higher efficiency of direct skin feeding assays, membrane feeding assays appear suitable tools to compare the infectiousness between individuals and to evaluate transmission-reducing interventions. Several aspects of membrane feeding procedures currently lack standardization; this variability makes comparisons between laboratories challenging and should be addressed to facilitate future testing of transmission-reducing interventions. 相似文献92.
Direct visualization of the outer membrane of mycobacteria and corynebacteria in their native state 总被引:1,自引:0,他引:1
Zuber B Chami M Houssin C Dubochet J Griffiths G Daffé M 《Journal of bacteriology》2008,190(16):5672-5680
The cell envelope of mycobacteria, which include the causative agents of tuberculosis and leprosy, is crucial for their success as pathogens. Despite a continued strong emphasis on identifying the multiple chemical components of this envelope, it has proven difficult to combine its components into a comprehensive structural model, primarily because the available ultrastructural data rely on conventional electron microscopy embedding and sectioning, which are known to induce artifacts. The existence of an outer membrane bilayer has long been postulated but has never been directly observed by electron microscopy of ultrathin sections. Here we have used cryo-electron microscopy of vitreous sections (CEMOVIS) to perform a detailed ultrastructural analysis of three species belonging to the Corynebacterineae suborder, namely, Mycobacterium bovis BCG, Mycobacterium smegmatis, and Corynebacterium glutamicum, in their native state. We provide new information that accurately describes the different layers of the mycobacterial cell envelope and challenges current models of the organization of its components. We show a direct visualization of an outer membrane, analogous to that found in gram-negative bacteria, in the three bacterial species examined. Furthermore, we demonstrate that mycolic acids, the hallmark of mycobacteria and related genera, are essential for the formation of this outer membrane. In addition, a granular layer and a low-density zone typifying the periplasmic space of gram-positive bacteria are apparent in CEMOVIS images of mycobacteria and corynebacteria. Based on our observations, a model of the organization of the lipids in the outer membrane is proposed. The architecture we describe should serve as a reference for future studies to relate the structure of the mycobacterial cell envelope to its function. 相似文献
93.
Kaddouri H Djimdé A Dama S Kodio A Tekete M Hubert V Koné A Maiga H Yattara O Fofana B Sidibe B Sangaré CP Doumbo O Le Bras J 《International journal for parasitology》2008,38(7):791-798
In vitro susceptibility to antimalarial drugs of Malian Plasmodium falciparum isolates collected between 2004 and 2006 was studied. Susceptibility to chloroquine and to three artemisinin-based combination therapy (ACT) component drugs was assessed as a first, to our knowledge, in vitro susceptibility study in Mali. Overall 96 Malian isolates (51 from around Bamako and 45 collected from French travellers returning from Mali) were cultivated in a CO2 incubator. Fifty percent inhibitory concentrations (IC50s) were measured by either hypoxanthine incorporation or Plasmodium lactate dehydrogenase (pLDH) ELISA. Although the two sets of data were generated with different methods, the global IC50 distributions showed parallel trends. A good concordance of resistance phenotype with pfcrt 76T mutant genotype was found within the sets of clinical isolates tested. We confirm a high prevalence of P. falciparum in vitro resistance to chloroquine in Mali (60–69%). While some isolates showed IC50s close to the cut-off for resistance to monodesethylamodiaquine, no decreased susceptibility to dihydroartemisinin or lumefantrine was detected. This study provides baseline data for P. falciparum in vitro susceptibility to ACT component drugs in Mali. 相似文献
94.
Laval F Haites R Movahedzadeh F Lemassu A Wong CY Stoker N Billman-Jacobe H Daffé M 《The Journal of biological chemistry》2008,283(3):1419-1427
Mycolic acids are major and specific lipid components of the cell envelope of mycobacteria that include the causative agents of tuberculosis and leprosy, Mycobacterium tuberculosis and Mycobacterium leprae, respectively. Subtle structural variations that are known to be crucial for both their virulence and the permeability of their cell envelope occur in mycolic acids. Among these are the introduction of cyclopropyl groups and methyl branches by mycolic acid S-adenosylmethionine-dependent methyltransferases (MA-MTs). While the functions of seven of the M. tuberculosis MA-MTs have been either established or strongly presumed nothing is known of the roles of the remaining umaA gene product and those of M. smegmatis MA-MTs. Mutants of the M. tuberculosis umaA gene and its putative M. smegmatis orthologue, MSMEG0913, were created. The lipid extracts of the resulting mutants were analyzed in detail using a combination of analytical techniques such as matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and proton nuclear magnetic resonance spectroscopy, and chemical degradation methods. The M. smegmatis mutants no longer synthesized subtypes of mycolates containing a methyl branch adjacent to either trans cyclopropyl group or trans double bond at the "proximal" position of both alpha- and epoxy-mycolates. Complementation with MSMEG0913, but not with umaA, fully restored the wild-type phenotype in M. smegmatis. Consistently, no modification was observed in the structures of mycolic acids produced by the M. tuberculosis umaA mutant. These data proved that despite their synteny and high similarity umaA and MSMEG0913 are not functionally orthologous. 相似文献
95.
Contemporary variations of immune responsiveness during range expansion of two invasive rodents in Senegal
下载免费PDF全文
![点击此处可从《Oikos》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Christophe Diagne Emmanuelle Gilot‐Fromont Stéphane Cornet Laëtitia Husse Souleymane Doucouré Ambroise Dalecky Khalilou Bâ Mamadou Kane Youssoupha Niang Mamoudou Diallo Aliou Sow Odile Fossati‐Gaschignard Sylvain Piry Emmanuelle Artige Mbacké Sembène Carine Brouat Nathalie Charbonnel 《Oikos》2017,126(3):435-446
Biological invasions provide unique opportunities for studying life history trait changes over contemporary time scales. As spatial spread may be related to changes in parasite communities, several hypotheses (such as the evolution of increased competitive ability (EICA) or EICA‐refined hypotheses) suggest immune changes in invasive species along invasion gradients. Although native hosts may be subject to similar changes in parasite selection pressures, their immune responses have been rarely investigated in invasion contexts. In this study, we evaluated immune variations for invasive house mice Mus musculus domesticus, invasive black rats Rattus rattus and native rodents Mastomys erythroleucus and Mastomys natalensis along well‐characterised invasion gradients in Senegal. We focused on antibody‐mediated (natural antibodies and complement) and inflammatory (haptoglobin) responses. One invasion route was considered for each invasive species, and environmental conditions were recorded. Natural‐antibody mediated responses increased between sites of long‐established invasion and recently invaded sites only in house mice. Both invasive species exhibited higher inflammatory responses at the invasion front than in sites of long‐established invasion. The immune responses of native species did not change with the presence of invasive species. These patterns of immune variations do not support the EICA and EICA refined hypotheses, and they rather suggest a higher risk of exposure to parasites on the invasion front. Altogether, these results provide a first basis to further assess the role of immune changes in invasion success. 相似文献
96.
Assessing global patterns in mammalian carnivore occupancy and richness by integrating local camera trap surveys
下载免费PDF全文
![点击此处可从《Global Ecology and Biogeography》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Lindsey N. Rich Courtney L. Davis Zach J. Farris David A. W. Miller Jody M. Tucker Sandra Hamel Mohammad S. Farhadinia Robin Steenweg Mario S. Di Bitetti Kanchan Thapa Mamadou D. Kane S. Sunarto Nathaniel P. Robinson Agustín Paviolo Paula Cruz Quinton Martins Navid Gholikhani Ateih Taktehrani Jesse Whittington Febri A. Widodo Nigel G. Yoccoz Claudia Wultsch Bart J. Harmsen Marcella J. Kelly 《Global Ecology and Biogeography》2017,26(8):918-929
97.
Veyron-Churlet R Bigot S Guerrini O Verdoux S Malaga W Daffé M Zerbib D 《Journal of molecular biology》2005,353(4):847-858
Tuberculosis kills about two million people every year and remains one of the leading causes of mortality worldwide. As a result of the increasing antibiotic resistance of Mycobacterium tuberculosis (Mtb) strains, there is an urgent need for new antitubercular drugs. Several efficient antibiotics, including isoniazid, specifically target the fatty acid synthase-II (FAS-II) complex of mycolic acid biosynthesis. We have previously shown that there are protein-protein interactions between the components of FAS-II that are essential for mycobacterial survival. We have now looked at the potential partners of FAS-II, mtFabD, the methyltransferases MmaAs, and Pks13. A combination of yeast two-hybrid and co-immunoprecipitation experiments showed that mtFabD interacts with each beta-ketoacyl-synthase (KasA, KasB and mtFabH) and with the core of FAS-II (InhA and MabA). The methyltransferases have a greater affinity for KasA and KasB than for mtFabH, suggesting that modifications on the meromycolic chains may occur during their elongation. Finally, Pks13, which catalyzes the final Claisen condensation of mycolic acids, interacts specifically with KasB. These data allowed us to determine the architecture of the multiple specialized FAS-II complexes, giving us insights into the organization of the complete mycolic acids biosynthesis. Our studies suggest a new and crucial interaction (KasB-Pks13) as a putative target for peptidomimetic antibiotics. 相似文献
98.
Mumme J Eckervogt L Pielert J Diakité M Rupp F Kern J 《Bioresource technology》2011,102(19):9255-9260
Hydrochars were prepared by hydrothermal carbonization (HTC) of maize silage previously treated at 55 °C in a two-stage solid-state reactor system. The HTC was carried out in a 1-L stirred pressure reactor with pH regulation by citric acid. The treated silage carbonized at relatively mild conditions (190 °C, 2 h), and the hydrochars showed mainly amorphous macro-size features with a carbon content of 59-79% (ash-free, dry) and a higher heating value of 25-36 MJ kg?1. Temperature was the main influencing factor. The surface area according to Brunauer-Emmett-Teller (BET) analysis was highest at 190 °C (12.3 m2) g?1). Based on these results, the hydrochars are potentially interesting for applications such as an alternative fuel or a soil conditioner. 相似文献
99.
Cell wall peptidolipids of Mycobacterium avium: from genetic prediction to exact structure of a nonribosomal peptide
下载免费PDF全文
![点击此处可从《Molecular microbiology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
John P. Bannantine Gilles Etienne Françoise Laval Judith R. Stabel Anne Lemassu Mamadou Daffé Darrell O. Bayles Christelle Ganneau Frédéric Bonhomme Maxime Branger Thierry Cochard Sylvie Bay Franck Biet 《Molecular microbiology》2017,105(4):525-539
Mycobacteria have a complex cell wall structure that includes many lipids; however, even within a single subspecies of Mycobacterium avium these lipids can differ. Total lipids from an M. avium subsp. paratuberculosis (Map) ovine strain (S‐type) contained no identifiable glycopeptidolipids or lipopentapeptide (L5P), yet both lipids are present in other M. avium subspecies. We determined the genetic and phenotypic basis for this difference using sequence analysis as well as biochemical and physico‐chemical approaches. This strategy showed that a nonribosomal peptide synthase, encoded by mps1, contains three amino acid specifying modules in ovine strains, compared to five modules in bovine strains (C‐type). Sequence analysis predicted these modules would produce the tripeptide Phe‐N‐Methyl‐Val‐Ala with a lipid moiety, termed lipotripeptide (L3P). Comprehensive physico‐chemical analysis of Map S397 extracts confirmed the structural formula of the native L3P as D‐Phe‐N‐Methyl‐L‐Val‐L‐Ala‐OMe attached in N‐ter to a 20‐carbon fatty acid chain. These data demonstrate that S‐type strains, which are more adapted in sheep, produce a unique lipid. There is a dose‐dependent effect observed for L3P on upregulation of CD25+ CD8 T cells from infected cows, while L5P effects were static. In contrast, L5P demonstrated a significantly stronger induction of CD25+ B cells from infected animals compared to L3P. 相似文献
100.