全文获取类型
收费全文 | 2105篇 |
免费 | 172篇 |
国内免费 | 1篇 |
专业分类
2278篇 |
出版年
2024年 | 4篇 |
2023年 | 21篇 |
2022年 | 24篇 |
2021年 | 45篇 |
2020年 | 32篇 |
2019年 | 43篇 |
2018年 | 57篇 |
2017年 | 60篇 |
2016年 | 72篇 |
2015年 | 126篇 |
2014年 | 132篇 |
2013年 | 148篇 |
2012年 | 184篇 |
2011年 | 163篇 |
2010年 | 104篇 |
2009年 | 97篇 |
2008年 | 125篇 |
2007年 | 111篇 |
2006年 | 127篇 |
2005年 | 109篇 |
2004年 | 88篇 |
2003年 | 87篇 |
2002年 | 85篇 |
2001年 | 31篇 |
2000年 | 16篇 |
1999年 | 19篇 |
1998年 | 17篇 |
1997年 | 15篇 |
1996年 | 10篇 |
1995年 | 18篇 |
1994年 | 10篇 |
1993年 | 13篇 |
1992年 | 10篇 |
1991年 | 10篇 |
1990年 | 14篇 |
1989年 | 9篇 |
1988年 | 14篇 |
1987年 | 4篇 |
1986年 | 5篇 |
1985年 | 4篇 |
1982年 | 2篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1974年 | 3篇 |
1973年 | 1篇 |
1972年 | 1篇 |
1971年 | 1篇 |
1970年 | 1篇 |
1960年 | 1篇 |
排序方式: 共有2278条查询结果,搜索用时 15 毫秒
991.
992.
993.
994.
Román Serrat Guillermo López-Doménech Serena Mirra Martí Quevedo Jordi Garcia-Fernàndez Fausto Ulloa Ferrán Burgaya Eduardo Soriano 《PloS one》2013,8(7)
The regulation of mitochondrial dynamics is vital in complex cell types, such as neurons, that transport and localize mitochondria in high energy-demanding cell domains. The Armcx3 gene encodes a mitochondrial-targeted protein (Alex3) that contains several arm-like domains. In a previous study we showed that Alex3 protein regulates mitochondrial aggregation and trafficking. Here we studied the contribution of Wnt proteins to the mitochondrial aggregation and dynamics regulated by Alex3. Overexpression of Alex3 in HEK293 cells caused a marked aggregation of mitochondria, which was attenuated by treatment with several Wnts. We also found that this decrease was caused by Alex3 degradation induced by Wnts. While the Wnt canonical pathway did not alter the pattern of mitochondrial aggregation induced by Alex3, we observed that the Wnt/PKC non-canonical pathway regulated both mitochondrial aggregation and Alex3 protein levels, thereby rendering a mitochondrial phenotype and distribution similar to control patterns. Our data suggest that the Wnt pathway regulates mitochondrial distribution and dynamics through Alex3 protein degradation. 相似文献
995.
Increasing drought decreases phosphorus availability in an evergreen Mediterranean forest 总被引:9,自引:2,他引:7
Mediterranean ecosystems are water-limited and frequently also nutrient-limited. We aimed to investigate the effects of increasing
drought, as predicted by GCM and eco-physiological models for the next decades, on the P cycle and P plant availability in
a Mediterranean forest. We conducted a field experiment in a mature evergreen oak forest, establishing four drought-treatment
plots and four control plots (150 m2 each). After three years, the runoff and rainfall exclusion reduced an overall 22% the soil moisture, and the runoff exclusion
alone reduced it 10%. The reduction of 22% in soil moisture produced a decrease of 40% of the accumulated aboveground plant
P content, above all because there was a smaller increase in aerial biomass. The plant leaf P content increased by 100 ± 40
mg m−2 in the control plots, whereas it decreased by 40 ± 40 mg m−2 in the drought plots. The soil Po-NaHCO3 (organic labile-P fraction) increased by 25% in consonance with the increase in litterfall, while the inorganic labile-P
fraction decreased in relation to the organic labile-P fraction up to 48%, indicating a decrease in microbial activity. Thus,
after just three years of slight drought, a clear trend towards an accumulation of P in the soil and towards a decrease of
P in the stand biomass was observed. The P accumulation in the soil in the drought plots was mainly in forms that were not
directly available to plants. These indirect effects of drought including the decrease in plant P availability, may become
a serious constraint for plant growth and therefore may have a serious effect on ecosystem performance. 相似文献
996.
997.
998.
Karen B. Disante Jordi Cortina Alberto Vilagrosa David Fuentes Encarni I. Hernández Karin Ljung 《Physiologia plantarum》2014,150(3):412-424
Heavy metal contamination and drought are expected to increase in large areas worldwide. However, their combined effect on plant performance has been scantly analyzed. This study examines the effect of Zn supply at different water availabilities on morpho‐physiological traits of Quercus suber L. in order to analyze the combined effects of both stresses. Seedlings were treated with four levels of zinc from 3 to 150 µM and exposed to low watering (LW) or high watering (HW) frequency in hydroponic culture, using a growth chamber. Under both watering regimes, Zn concentration in leaves and roots increased with Zn increment in nutrient solution. Nevertheless, at the highest Zn doses, Zn tissue concentrations were almost twice in HW than in LW seedlings. Functional traits as leaf photosynthetic rate and root hydraulic conductivity, and morphological traits as root length and root biomass decreased significantly in response to Zn supply. Auxin levels increased with Zn concentrations, suggesting the involvement of this phytohormone in the seedling response to this element. LW seedlings exposed to 150 µM Zn showed higher root length and root biomass than HW seedlings exposed to the same Zn dose. Our results suggest that low water availability could mitigate Zn toxicity by limiting internal accumulation. Morphological traits involved in the response to both stresses probably contributed to this response. 相似文献
999.
Marc Yeste Efrén Estrada Elisabeth Pinart Sergi Bonet Jordi Miró Joan E. Rodríguez-Gil 《Cryobiology》2014
Reduced glutathione (GSH) improves boar sperm cryosurvival and fertilising ability when added to freezing extenders. Poor freezability ejaculates (PFE) are known to present lower resistance than good freezability ejaculates (GFE) to cryopreservation procedures. So far, no study has evaluated whether the ability of GSH to counteract the cryopreservation-induced injuries depends on ejaculate freezability (i.e. GFE vs. PFE). For this reason, thirty boar ejaculates were divided into three equal volume fractions and cryopreserved with or without GSH at a final concentration of either 2 or 5 mM in freezing media. Before and after freeze–thawing, sperm quality was evaluated through analysis of viability, motility, integrity of outer acrosome membrane, ROS levels, integrity of nucleoprotein structure, and DNA fragmentation. Ejaculates were classified into two groups (GFE or PFE) according to their post-thaw sperm motility and viability assessments in negative control (GSH 0 mM), after running cluster analyses. Values of each sperm parameter were then compared between treatments (GSH 0 mM, GSH 2 mM, GSH 5 mM) and freezability groups (GFE, PFE). In the case of GFE, GSH significantly improved boar sperm cryotolerance, without differences between 2 and 5 mM. In contrast, PFE freezability was significantly increased when supplemented with 5 mM GSH, but not when supplemented with 2 mM GSH. In conclusion, PFE need a higher concentration of GSH than GFE to improve their cryotolerance. 相似文献
1000.
Ana-Maria Hereş Jesús Julio Camarero Bernat C. López Jordi Martínez-Vilalta 《Trees - Structure and Function》2014,28(6):1737-1750