全文获取类型
收费全文 | 268篇 |
免费 | 22篇 |
出版年
2023年 | 2篇 |
2022年 | 2篇 |
2021年 | 2篇 |
2020年 | 2篇 |
2019年 | 3篇 |
2018年 | 3篇 |
2017年 | 2篇 |
2016年 | 5篇 |
2015年 | 12篇 |
2014年 | 10篇 |
2013年 | 11篇 |
2012年 | 27篇 |
2011年 | 24篇 |
2010年 | 15篇 |
2009年 | 14篇 |
2008年 | 14篇 |
2007年 | 12篇 |
2006年 | 9篇 |
2005年 | 22篇 |
2004年 | 22篇 |
2003年 | 9篇 |
2002年 | 15篇 |
2001年 | 4篇 |
2000年 | 1篇 |
1999年 | 3篇 |
1998年 | 3篇 |
1996年 | 1篇 |
1995年 | 2篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1992年 | 6篇 |
1991年 | 4篇 |
1990年 | 5篇 |
1989年 | 4篇 |
1988年 | 1篇 |
1987年 | 3篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1984年 | 4篇 |
1982年 | 1篇 |
1981年 | 2篇 |
1980年 | 2篇 |
1978年 | 1篇 |
1969年 | 1篇 |
1964年 | 1篇 |
排序方式: 共有290条查询结果,搜索用时 15 毫秒
1.
2.
Nívia Carolina Nogueira-Paiva Paula Melo de Abreu Vieira Larissa Maris Rezende Oliveri Kátia da Silva Fonseca Gwenaelle Pound-Lana Maykon Tavares de Oliveira Marta de Lana Vanja Maria Veloso Alexandre Barbosa Reis Washington Luiz Tafuri Cláudia Martins Carneiro 《PloS one》2015,10(9)
The present study aims at establishing whether the diversity in pathogenesis within a genetically diverse host population infected with a single polyclonal strain of Trypanosoma cruzi is due to selection of specific subpopulations within the strain. For this purpose we infected Swiss mice, a genetically diverse population, with the polyclonal strain of Trypanosoma cruzi Berenice-78 and characterized via LSSP-PCR the kinetoplast DNA of subpopulations isolated from blood samples collected from the animals at various times after inoculation (3, 6 and 12 months after inoculation). We examined the biological behavior of the isolates in acellular medium and in vitro profiles of infectivity in Vero cell medium. We compared the characteristics of the isolates with the inoculating strain and with another strain, Berenice 62, isolated from the same patient 16 years earlier. We found that one of the isolates had intermediate behavior in comparison with Berenice-78 and Berenice-62 and a significantly different genetic profile by LSSP-PCR in comparison with the inoculating strain. We hereby demonstrate that genetically distinct Trypanosoma cruzi isolates may be obtained upon experimental murine infection with a single polyclonal Trypanosoma cruzi strain. 相似文献
3.
F. A. Maris E. Dingler S. Niehues 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》1999,721(2):145
A validated HPLC method for the simultaneous quantitative analysis of the antidepressant mirtazapine and its demethyl metabolite in human plasma is described. The active constituents including internal standard were extracted from 1 ml of plasma with hexane and separated on a μBondapak Phenyl column with fluorescence detection. The lower limit of quantification was 0.5 ng/ml, without significant interferences with endogenous or exogenous components. Inter- and intra-assay accuracy determined at quality control levels of 2, 10 and 80 ng/ml were, respectively, 104.6–113.7% and 105.1–117.7% for mirtazapine, and 91.7–99.3% and 89.9–103.7% for demethylmirtazapine. In all cases the precision was below 6.8%. 相似文献
4.
The Scheldt estuary: a description of a changing ecosystem 总被引:2,自引:0,他引:2
Patrick Meire Tom Ysebaert Stefan Van Damme Erika Van den Bergh Tom Maris Eric Struyf 《Hydrobiologia》2005,540(1-3):1-11
5.
Herbivore arthropods benefit from vectoring plant viruses 总被引:5,自引:0,他引:5
Belén Belliure Arne Janssen † Paul C. Maris Dick Peters Maurice W. Sabelis 《Ecology letters》2005,8(1):70-79
Plants infected with pathogens often attract the pathogens’ vectors, but it is not clear if this is advantageous to the vectors. We therefore quantified the direct and indirect (through the host plant) effects of a pathogen on its vector. A positive direct effect of the plant‐pathogenic Tomato spotted wilt virus on its thrips vector (Frankliniella occidentalis) was found, but the main effect was indirect; juvenile survival and developmental rate of thrips was lower on pepper plants that were damaged by virus‐free thrips than on unattacked plants, but such negative effects were absent on plants that were damaged and inoculated by infected thrips or were mechanically inoculated with the virus. Hence, potential vectors benefit from attacking plants with virus because virus‐infected plants are of higher quality for the vector's offspring. We propose that plant pathogens in general have evolved mechanisms to overcome plant defences against their vectors, thus promoting pathogen spread. 相似文献
6.
Nicky D'Haene Sébastien Sauvage Calliope Maris Ivan Adanja Marie Le Mercier Christine Decaestecker Linda Baum Isabelle Salmon 《PloS one》2013,8(6)
Aim
Accumulating evidence suggests that extracellular galectin-1 and galectin-3 promote angiogenesis. Increased expression of galectin-1 and/or galectin-3 has been reported to be associated with tumour progression. Thus, it is critical to identify their influence on angiogenesis.Methods
We examined the individual and combined effects of galectin-1 and galectin-3 on endothelial cell (EC) growth and tube formation using two EC lines, EA.hy926 and HUVEC. The activation of vascular endothelial growth factor receptors (VEGFR1 and VEGFR2) was determined by ELISA and Western blots. We evaluated the VEGFR1 and VEGFR2 levels in endosomes by proximity ligation assay.Results
We observed different responses to exogenous galectins depending on the EC line. An enhanced effect on EA.hy926 cell growth and tube formation was observed when both galectins were added together. Focusing on this enhanced effect, we observed that together galectins induced the phosphorylation of both VEGFR1 and VEGFR2, whereas galectin-1 and −3 alone induced VEGFR2 phosphorylation only. In the same way, the addition of a blocking VEGFR1 antibody completely abolished the increase in tube formation induced by the combined addition of both galectins. In contrast, the addition of a blocking VEGFR2 antibody only partially inhibited this effect. Finally, the addition of both galectins induced a decrease in the VEGFR1 and VEGFR2 endocytic pools, with a significantly enhanced effect on the VEGFR1 endocytic pool. These results suggest that the combined action of galectin-1 and galectin-3 has an enhanced effect on angiogenesis via VEGFR1 activation, which could be related to a decrease in receptor endocytosis. 相似文献7.
8.
Peteris Prusis Staffan Uhlén Ramona Petrovska Maris Lapinsh Jarl ES Wikberg 《BMC bioinformatics》2006,7(1):167-13
Background
Both direct and indirect interactions determine molecular recognition of ligands by proteins. Indirect interactions can be defined as effects on recognition controlled from distant sites in the proteins, e.g. by changes in protein conformation and mobility, whereas direct interactions occur in close proximity of the protein's amino acids and the ligand. Molecular recognition is traditionally studied using three-dimensional methods, but with such techniques it is difficult to predict the effects caused by mutational changes of amino acids located far away from the ligand-binding site. We recently developed an approach, proteochemometrics, to the study of molecular recognition that models the chemical effects involved in the recognition of ligands by proteins using statistical sampling and mathematical modelling. 相似文献9.
Juan Pablo Rigalli Nadia Ciriaci Agostina Arias María Paula Ceballos Silvina Stella Maris Villanueva Marcelo Gabriel Luquita Aldo Domingo Mottino Carolina Inés Ghanem Viviana Alicia Catania María Laura Ruiz 《PloS one》2015,10(3)
Hepatocellular carcinoma (HCC) is the fifth most frequent cancer worldwide. Sorafenib is the only drug available that improves the overall survival of HCC patients. P-glycoprotein (P-gp), Multidrug resistance-associated proteins 2 and 3 (MRP2 and 3) and Breast cancer resistance protein (BCRP) are efflux pumps that play a key role in cancer chemoresistance. Their modulation by dietary compounds may affect the intracellular accumulation and therapeutic efficacy of drugs that are substrates of these transporters. Genistein (GNT) is a phytoestrogen abundant in soybean that exerts its genomic effects through Estrogen-Receptors and Pregnane-X-Receptor (PXR), which are involved in the regulation of the above-mentioned transporters. We evaluated the effect of GNT on the expression and activity of P-gp, MRP2, MRP3 and BCRP in HCC-derived HepG2 cells. GNT (at 1.0 and 10 μM) increased P-gp and MRP2 protein expression and activity, correlating well with an increased resistance to sorafenib cytotoxicity as detected by the methylthiazole tetrazolium (MTT) assay. GNT induced P-gp and MRP2 mRNA expression at 10 but not at 1.0 μM concentration suggesting a different pattern of regulation depending on the concentration. Induction of both transporters by 1.0 μM GNT was prevented by cycloheximide, suggesting translational regulation. Downregulation of expression of the miR-379 by GNT could be associated with translational regulation of MRP2. Silencing of PXR abolished P-gp induction by GNT (at 1.0 and 10 μM) and MRP2 induction by GNT (only at 10 μM), suggesting partial mediation of GNT effects by PXR. Taken together, the data suggest the possibility of nutrient-drug interactions leading to enhanced chemoresistance in HCC when GNT is ingested with soy rich diets or dietary supplements. 相似文献
10.
Ana Todorovic Jan-Mathijs Schoffelen Freek van Ede Eric Maris Floris P. de Lange 《PloS one》2015,10(3)
The neural response to a stimulus is influenced by endogenous factors such as expectation and attention. Current research suggests that expectation and attention exert their effects in opposite directions, where expectation decreases neural activity in sensory areas, while attention increases it. However, expectation and attention are usually studied either in isolation or confounded with each other. A recent study suggests that expectation and attention may act jointly on sensory processing, by increasing the neural response to expected events when they are attended, but decreasing it when they are unattended. Here we test this hypothesis in an auditory temporal cueing paradigm using magnetoencephalography in humans. In our study participants attended to, or away from, tones that could arrive at expected or unexpected moments. We found a decrease in auditory beta band synchrony to expected (versus unexpected) tones if they were unattended, but no difference if they were attended. Modulations in beta power were already evident prior to the expected onset times of the tones. These findings suggest that expectation and attention jointly modulate sensory processing. 相似文献