全文获取类型
收费全文 | 56篇 |
免费 | 2篇 |
出版年
2021年 | 1篇 |
2020年 | 1篇 |
2017年 | 2篇 |
2016年 | 1篇 |
2015年 | 2篇 |
2014年 | 2篇 |
2013年 | 5篇 |
2012年 | 2篇 |
2011年 | 1篇 |
2010年 | 3篇 |
2009年 | 3篇 |
2008年 | 2篇 |
2007年 | 3篇 |
2006年 | 2篇 |
2005年 | 2篇 |
2003年 | 1篇 |
1998年 | 3篇 |
1997年 | 1篇 |
1996年 | 1篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1984年 | 2篇 |
1978年 | 1篇 |
1972年 | 1篇 |
1971年 | 1篇 |
1968年 | 2篇 |
1967年 | 1篇 |
1964年 | 2篇 |
1963年 | 2篇 |
1962年 | 1篇 |
1959年 | 1篇 |
1955年 | 2篇 |
1947年 | 1篇 |
排序方式: 共有58条查询结果,搜索用时 26 毫秒
31.
Cousins MM Laeyendecker O Beauchamp G Brookmeyer R Towler WI Hudelson SE Khaki L Koblin B Chesney M Moore RD Kelen GD Coates T Celum C Buchbinder SP Seage GR Quinn TC Donnell D Eshleman SH 《PloS one》2011,6(11):e27211
Background
Cross-sectional assessment of HIV incidence relies on laboratory methods to discriminate between recent and non-recent HIV infection. Because HIV diversifies over time in infected individuals, HIV diversity may serve as a biomarker for assessing HIV incidence. We used a high resolution melting (HRM) diversity assay to compare HIV diversity in adults with different stages of HIV infection. This assay provides a single numeric HRM score that reflects the level of genetic diversity of HIV in a sample from an infected individual.Methods
HIV diversity was measured in 203 adults: 20 with acute HIV infection (RNA positive, antibody negative), 116 with recent HIV infection (tested a median of 189 days after a previous negative HIV test, range 14–540 days), and 67 with non-recent HIV infection (HIV infected >2 years). HRM scores were generated for two regions in gag, one region in pol, and three regions in env.Results
Median HRM scores were higher in non-recent infection than in recent infection for all six regions tested. In multivariate models, higher HRM scores in three of the six regions were independently associated with non-recent HIV infection.Conclusions
The HRM diversity assay provides a simple, scalable method for measuring HIV diversity. HRM scores, which reflect the genetic diversity in a viral population, may be useful biomarkers for evaluation of HIV incidence, particularly if multiple regions of the HIV genome are examined. 相似文献32.
33.
34.
Chemical composition, antioxidant and antimicrobial properties of the essential oils of three Salvia species from Turkish flora 总被引:1,自引:0,他引:1
Essential oils of three different Salvia species [Salvia aucheri var. aucheri (endemic), Salvia aramiensis and Salvia pilifera (endemic)] were screened for their possible antioxidant and antimicrobial properties as well as their chemical compositions. According to the gas chromatography (GC)/EIMS (gas chromatography/electron impact mass spectrum) analysis results; 41 (97.2%), 51 (98.5%) and 83 compounds (98.2%) were identified, respectively. While 1,8-cineole (30.5%), camphor (21.3%) and borneol (8.50%) are the major compounds for S. aucheri var. aucheri oil, beta-pinene (10.3%), was the main constituent for S. aramienesis together with 1,8-cineole (46.0%) and camphor (8.7%). In the case of S. pilifera oil, alpha-thujene (36.1%) and alpha-pinene (13.8%) determined as the major compounds. Antioxidant activity was employed by two complementary test systems namely 2,2'-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging and beta-carotene/linoleic acid systems. Antioxidant activity of S. aramiensis was found to be higher than those of the others for the both systems (12.26+/-1.09 and 92.46%+/-1.64 microg mg(-1), respectively). Additionally, antioxidant activities of BHT, curcumin, ascorbic acid and alpha-tocopherol were determined in parallel experiments. In the case of antimicrobial activity, similar activity pattern was obtained (both in disc diffusion and MIC tests). Antimicrobial activity of S. aramiensis was followed by S. aucheri var. aucheri and S. pilifera, respectively. In these experiments, the most sensitive microorganism Acinetobacter lwoffii was followed by Candida albicans. 相似文献
35.
MOTIVATION: Recently, we described a Maximum Weighted Matching (MWM) method
for RNA structure prediction. The MWM method is capable of detecting
pseudoknots and other tertiary base-pairing interactions in a
computationally efficient manner (Cary and Stormo, Proceedings of the Third
International Conference on Intelligent Systems for Molecular Biology, pp.
75-80, 1995). Here we report on the results of our efforts to improve the
MWM method's predictive accuracy, and show how the method can be extended
to detect base interactions formerly inaccessible to automated RNA modeling
techniques. RESULTS: Improved performance in MWM structure prediction was
achieved in two ways. First, new ways of calculating base pair likelihoods
have been developed. These allow experimental data and combined statistical
and thermodynamic information to be used by the program. Second, accuracy
was improved by developing techniques for filtering out spurious base pairs
predicted by the MWM program. We also demonstrate here a means by which the
MWM folding method may be used to detect the presence of base triples in
RNAs. AVAILABILITY: http://www.cshl.org/mzhanglab/tabaska/j axpage. html
CONTACT: tabaska@cshl.org
相似文献
36.
Hyphae of Saprolegnia ferax growing under normal or low-turgor conditions were exposed to 0.1-10 &mgr;g/ml latrunculin B, an actin inhibitor. In the first 10 s of addition, hyphae with normal turgor levels accelerated while those with low turgor decelerated, consistent with the suggestion that actin restrains or protrudes tips under these respective turgor conditions. Both sets of hyphae then decelerated and eventually ceased extension within 60 s. These changes were reflected in rhodamine-phalloidin staining patterns, which showed that actin caps were disrupted progressively under both conditions in a time-dependent manner. After 60 s, normal-turgored hyphae started to swell rapidly while low-turgored hyphae showed little or no swelling. Swelling was characteristically subapical, which is best explained by tip growth models which incorporate actin-mediated exocytosis. 相似文献
37.
van Hoek AH; van Alen TA; Sprakel VS; Hackstein JH; Vogels GD 《Molecular biology and evolution》1998,15(9):1195-1206
The 18S and 5.8S rDNA genes and the internal transcribed spacers ITS-1 and
ITS-2 of ciliates living in the hindgut of frogs, millipedes, and
cockroaches were analyzed in order to study the evolution of intestinal
protists. All ciliates studied here belong to the genus Nycrotherus.
Phylogenetic analysis revealed that these ciliates from a monophyletic
group that includes the distantly related anaerobic free-living
heterotrichous ciliates Metopus palaeformis and Metopus contortus. The
intestinal ciliates from the different vertebrate and invertebrate hosts
are clearly divergent at the level of their rDNA repeats. This argues for
the antiquity of the associations and a predominantly vertical
transmission. This mode of transmission seems to be controlled primarily by
the behavior of the host. The different degrees of divergence between
ciliates living in different strains of one and the same cockroach species
most likely reflect the different geographical origins of the hosts. In
addition, host switches must have occurred during the evolution of
cockroaches, since identical ciliates were found only in distantly related
hosts. These phenomena prevent the reconstruction of potential cospeciation
events.
相似文献
38.
GD Robson E Prebble A Rickers S Hosking DW Denning APJ Trinci W Robertson 《Fungal genetics and biology : FG & B》1996,20(4):289-298
Robson, G. D., Prebble, E., Rickers, A., Hosking, S., Denning, D. W., Trinci, A. P. J., and Robertson, W. 1996. Polarized growth of fungal hyphae is defined by an alkaline pH gradient. Fungal Genetics and Biology 20, 289-298. Polarized cell growth is exhibited by a diverse range of eukaryotic and prokaryotic cells. The events which are responsible for this growth are poorly understood. However, the existence of ion gradients may play an important role in establishing and driving cell polarity. Using a pH-sensitive, ratiometric fluorescent dye to monitor intracellular pH in growing fungal hyphae, we report a gradient at the extending hyphal tip that is up to 1.4 pH units more alkaline than more distal regions. Both the magnitude and the length of the pH gradient were strongly correlated with the rate of hyphal extension and eradication of the gradient-arrested growth. These results suggest that alkaline pH gradients may be integral to hyphal extension in fungi. 相似文献
39.
40.
James GD Prendergast Harry Campbell Nick Gilbert Malcolm G Dunlop Wendy A Bickmore Colin AM Semple 《BMC evolutionary biology》2007,7(1):72