全文获取类型
收费全文 | 1078篇 |
免费 | 98篇 |
出版年
2023年 | 5篇 |
2022年 | 7篇 |
2021年 | 25篇 |
2020年 | 13篇 |
2019年 | 34篇 |
2018年 | 22篇 |
2017年 | 28篇 |
2016年 | 40篇 |
2015年 | 57篇 |
2014年 | 58篇 |
2013年 | 59篇 |
2012年 | 115篇 |
2011年 | 70篇 |
2010年 | 38篇 |
2009年 | 49篇 |
2008年 | 60篇 |
2007年 | 47篇 |
2006年 | 54篇 |
2005年 | 42篇 |
2004年 | 45篇 |
2003年 | 39篇 |
2002年 | 29篇 |
2001年 | 17篇 |
2000年 | 21篇 |
1999年 | 24篇 |
1998年 | 21篇 |
1997年 | 15篇 |
1996年 | 7篇 |
1995年 | 12篇 |
1994年 | 14篇 |
1993年 | 10篇 |
1992年 | 9篇 |
1991年 | 8篇 |
1990年 | 12篇 |
1989年 | 3篇 |
1988年 | 8篇 |
1987年 | 9篇 |
1986年 | 8篇 |
1985年 | 11篇 |
1984年 | 2篇 |
1983年 | 4篇 |
1981年 | 3篇 |
1980年 | 2篇 |
1978年 | 2篇 |
1975年 | 3篇 |
1974年 | 4篇 |
1972年 | 3篇 |
1971年 | 2篇 |
1969年 | 1篇 |
1968年 | 1篇 |
排序方式: 共有1176条查询结果,搜索用时 796 毫秒
221.
Kenji F Shoji Pablo J Sáez Paloma A Harcha Hector L Aguila Juan C Sáez 《Channels (Austin, Tex.)》2014,8(2):142-156
Death of murine T cells induced by extracellular ATP is mainly triggered by activation of purinergic P2X7 receptors (P2X7Rs). However, a link between P2X7Rs and pannexin1 (Panx1) channels, which are non-selective, has been recently demonstrated in other cell types. In this work, we characterized the expression and cellular distribution of pannexin family members (Panxs 1, 2 and 3) in isolated T cells. Panx1 was the main pannexin family member clearly detected in both helper (CD4+) and cytotoxic (CD8+) T cells, whereas low levels of Panx2 were found in both T-cell subsets. Using pharmacological and genetic approaches, Panx1 channels were found to mediate most ATP-induced ethidium uptake since this was drastically reduced by Panx1 channel blockers (10Panx1, Probenecid and low carbenoxolone concentration) and absent in T cells derived from Panx1−/− mice. Moreover, electrophysiological measurements in wild-type CD4+ cells treated with ATP unitary current events and pharmacological sensitivity compatible with Panx1 channels were found. In addition, ATP release from T cells treated with 4Br-, a calcium ionophore, was completely blocked with inhibitors of both connexin hemichannels and Panx1 channels. Panx1 channel blockers drastically reduced the ATP-induced T-cell mortality, indicating that Panx1 channels mediate the ATP-induced T-cell death. However, mortality was not reduced in T cells of Panx1−/− mice, in which levels of P2X7Rs and ATP-induced intracellular free Ca2+ responses were enhanced suggesting that P2X7Rs take over Panx1 channels lose-function in mediating the onset of cell death induced by extracellular ATP. A23187相似文献
222.
María de la Luz Mohedano Pasquale Russo Vivian de los Ríos Vittorio Capozzi Pilar Fernández de Palencia Giuseppe Spano Paloma López 《Open biology》2014,4(2)
Oenococcus oeni is the main lactic acid bacterium that carries out the malolactic fermentation in virtually all red wines and in some white and sparkling wines. Oenococcus oeni possesses an array of metabolic activities that can modify the taste and aromatic properties of wine. There is, therefore, industrial interest in the proteins involved in these metabolic pathways and related transport systems of this bacterium. In this work, we report the characterization of the O. oeni ATCC BAA-1163 proteome. Total and membrane protein preparations from O. oeni were standardized and analysed by two-dimensional gel electrophoresis. Using tandem mass spectrometry, we identified 224 different spots corresponding to 152 unique proteins, which have been classified by their putative function and subjected to bioinformatics analysis. 相似文献
223.
Paloma Cariñanos Jean Emberlin Carmen Galán Eugenio Dominguez-Vilches 《Aerobiologia》2000,16(3-4):339-346
Two of the most frequently used methods of pollen counting on slides from Hirst type traps are evaluated in this paper: the
transverse traverse method and the longitudinal traverse method. The study was carried out during June–July 1996 and 1997
on slides from a trap at Worcester, UK. Three pollen types were selected for this purpose: Poaceae, Urticaceae and Quercus. The statistical results show that the daily concentrations followed similar trends (p < 0.01, R-values between 0.78–0.96)
with both methods during the two years, although the counts were slightly higher using the longitudinal traverses method.
Significant differences were observed, however, when the distribution of the concentrations during 24 hour sampling periods
was considered. For more detailed analysis, the daily counts obtained with both methods were correlated with the total number
of pollen grains for the taxon over the whole slide, in two different situations: high and low concentrations of pollen in
the atmosphere. In the case of high concentrations, the counts for all three taxa with both methods are significantly correlated
with the total pollen count. In the samples with low concentrations, the Poaceae and Urticaceae counts with both methods are
significantly correlated with the total counts, but none of Quercus counts are. Consideration of the results indicates that both methods give a reasonable approximation to the count derived
from the slide as a whole. More studies need be done to explore the comparability of counting methods in order to work towards
a Universal Methodology in Aeropalynology.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
224.
Solar radiation and functional traits explain the decline of forest primary productivity along a tropical elevation gradient
下载免费PDF全文
![点击此处可从《Ecology letters》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Nikolaos M. Fyllas Lisa Patrick Bentley Alexander Shenkin Gregory P. Asner Owen K. Atkin Sandra Díaz Brian J. Enquist William Farfan‐Rios Emanuel Gloor Rossella Guerrieri Walter Huaraca Huasco Yoko Ishida Roberta E. Martin Patrick Meir Oliver Phillips Norma Salinas Miles Silman Lasantha K Weerasinghe Joana Zaragoza‐Castells Yadvinder Malhi 《Ecology letters》2017,20(6):730-740
One of the major challenges in ecology is to understand how ecosystems respond to changes in environmental conditions, and how taxonomic and functional diversity mediate these changes. In this study, we use a trait‐spectra and individual‐based model, to analyse variation in forest primary productivity along a 3.3 km elevation gradient in the Amazon‐Andes. The model accurately predicted the magnitude and trends in forest productivity with elevation, with solar radiation and plant functional traits (leaf dry mass per area, leaf nitrogen and phosphorus concentration, and wood density) collectively accounting for productivity variation. Remarkably, explicit representation of temperature variation with elevation was not required to achieve accurate predictions of forest productivity, as trait variation driven by species turnover appears to capture the effect of temperature. Our semi‐mechanistic model suggests that spatial variation in traits can potentially be used to estimate spatial variation in productivity at the landscape scale. 相似文献
225.
226.
Biomanufacturing of protective antibodies and other therapeutics in edible plant tissues for oral applications
下载免费PDF全文
![点击此处可从《Plant biotechnology journal》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Paloma Juarez Vikram Virdi Ann Depicker Diego Orzaez 《Plant biotechnology journal》2016,14(9):1791-1799
Although plant expression systems used for production of therapeutic proteins have the advantage of being scalable at a low price, the downstream processing necessary to obtain pure therapeutic molecules is as expensive as for the traditional Chinese hamster ovary (CHO) platforms. However, when edible plant tissues (EPTs) are used, there is no need for exhaustive purification, because they can be delivered orally as partially purified formulations that are safe for consumption. This economic benefit is especially interesting when high doses of recombinant proteins are required throughout the treatment/prophylaxis period, as is the case for antibodies used for oral passive immunization (OPI). The secretory IgA (SIgA) antibodies, which are highly abundant in the digestive tract and mucosal secretions, and thus the first choice for OPI, have only been successfully produced in plant expression systems. Here, we cover most of the up‐to‐date examples of EPT‐produced pharmaceuticals, including two examples of SIgA aimed at oral delivery. We describe the benefits and drawbacks of delivering partially purified formulations and discuss a number of practical considerations and criteria to take into account when using plant expression systems, such as subcellular targeting, protein degradation, glycosylation patterns and downstream strategies, all crucial for improved yield, high quality and low cost of the final product. 相似文献
227.
The effect of temperature, pH, water potential and sources of nitrogen and carbon on the biocontrol agent Penicillium oxalicum
were studied in vitro. The fungus is xerotolerant, mesophillic and has a wide pH tolerance. The parameters evaluated (germination,
germ tube length, growth rate and sporulation) showed different sensitivities to the environmental factors. Peptone and free
amino acids gave the highest growth rates and high levels of sporulation. Xylose, mannose and fructose gave the highest growth
rates and mannose induced strong sporulation. The effect of nutrients (mannose + arginine) and water potential was also studied
in vivo. The xerotolerant character of the fungus was confirmed. From this study we consider Penicillium oxalicum ecologically
competent to perform effectively as a biocontrol agent in the soil environment.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
228.
Ignasi Bartomeus Daniel Sol Joan Pino Paloma Vicente Xavier Font 《Global Ecology and Biogeography》2012,21(5):524-533
Aim Classic theory suggests that species‐rich communities should be more resistant to the establishment of exotic species than species‐poor communities. Although this theory predicts that exotic species should be less diverse in regions that contain more native species, macroecological analyses often find that the correlation between exotic and native species richness is positive rather than negative. To reconcile results with theory, we explore to what extent climatic conditions, landscape heterogeneity and anthropogenic disturbance may explain the positive relationship between native and exotic plant richness. Location Catalonia (western Mediterranean region). Methods We integrated floristic records and GIS‐based environmental measures to make spatially explicit 10‐km grid cells. We asked whether the observed positive relationship between native and exotic plant richness (R2= 0.11) resulted from the addition of several negative correlations corresponding to different environmental conditions identified with cluster analysis. Moreover, we directly quantified the importance of common causal effects with a structural equation modelling framework. Results We found no evidence that the relationship between native and exotic plant richness was negative when the comparison was made within environmentally homogeneous groups. Although there were common factors explaining both native and exotic richness, mainly associated with landscape heterogeneity and human pressure, these factors only explained 17.2% of the total correlation. Nevertheless, when the comparison was restricted to native plants associated with human‐disturbed (i.e. ruderal) ecosystems, the relationship was stronger (R2= 0.52) and the fraction explained by common factors increased substantially (58.3%). Main conclusions While our results confirm that the positive correlation between exotic and native plant richness is in part explained by common extrinsic factors, they also highlight the great importance of anthropic factors that – by reducing biotic resistance – facilitate the establishment and spread of both exotic and native plants that tolerate disturbed environments. 相似文献
229.
230.