全文获取类型
收费全文 | 254篇 |
免费 | 15篇 |
国内免费 | 29篇 |
出版年
2024年 | 1篇 |
2023年 | 7篇 |
2022年 | 10篇 |
2021年 | 13篇 |
2020年 | 9篇 |
2019年 | 8篇 |
2018年 | 11篇 |
2017年 | 12篇 |
2016年 | 7篇 |
2015年 | 15篇 |
2014年 | 13篇 |
2013年 | 13篇 |
2012年 | 12篇 |
2011年 | 14篇 |
2010年 | 10篇 |
2009年 | 25篇 |
2008年 | 20篇 |
2007年 | 17篇 |
2006年 | 15篇 |
2005年 | 10篇 |
2004年 | 12篇 |
2003年 | 3篇 |
2002年 | 4篇 |
2001年 | 4篇 |
2000年 | 5篇 |
1999年 | 5篇 |
1998年 | 4篇 |
1997年 | 4篇 |
1996年 | 3篇 |
1995年 | 1篇 |
1994年 | 3篇 |
1990年 | 2篇 |
1988年 | 1篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1978年 | 1篇 |
排序方式: 共有298条查询结果,搜索用时 15 毫秒
271.
272.
Chlamydospores are vital asexual resting cells, which allow most of the Fusarium pathogenic strains to retain their longevity, thus ensuring survival of viable reproductive cells. This study suggested that both abiotic – extreme temperature and growth media, and biotic – antagonistic Bacillus amyloliquefaciens SMCD 518 and mycoparasititic Acremonium strictum SMCD 504 are natural stressors able to shift chlamydospores formation in Fusarium graminearum and F. sporotrichioides under in vitro conditions. In F. sporotrichioides, Minimal Conversion Media (MCM) with mannitol supplement induced high chlamydospore size, and chain abundance at optimal 21°C and extreme 37°C temperatures, respectively. F. graminearum showed low chlamydospore formation on MCM–mannitol, even when exposed to 37°C under prolonged 5 days incubation. Generally, F. sporotrichioides has higher chlamydospore abundance, longer chlamydospore chain, and production rapidity compared to F. graminearum in both abiotic and biotic treatments. However, biocontrol bacteria and mycoparasite posed minimal effects on chlamydospore formation, as compared to abiotic stressors, thus controlling the Fusaria but not triggering them to generate chlamydospores as protection shields. 相似文献
273.
Katarína Valentovi
ov
ubica Halukov Jana Huttov Igor Mistrík Ladislav Tams 《Environmental and Experimental Botany》2009,66(3):457-462
The effect of Cd on oxalate oxidase (OxO) activity and its localisation were analysed in barley root. In Cd-treated roots OxO activity was strongly induced in the region 2–4 mm behind the root tip and in the area toward the root base. In situ analyses showed that Cd-induced OxO activity was localised to the cell wall (CW) of early metaxylem vascular bundles and surrounding parenchyma cells and was accompanied by lignification of metaxylem vessels. OxO activation was also observed during treatment with other heavy metals (HMs), salt treatment and at elevated non-optimal temperature. In contrast to HM activation of OxO and lignification, high temperature and NaCl indeed activated OxO but did not induce lignification of metaxylem vessels. These results suggest that oxalate oxidase as an H2O2-generating enzyme is activated in response to several stresses, however the ectopic lignification of metaxylem vessels is activated specifically by HMs. This HM-induced premature root xylogenesis due to ectopic lignification of metaxylem vessels probably causes shortening of the root elongation zone and therefore a reduction in root growth. 相似文献
274.
275.
Question: 1. How do the competitive response and the importance of competition vary between species and along a flooding gradient? 2. How does the role of competition in constraining species distribution limits along the gradient vary between lower and upper limits? Location: A 1‐ha meadow within the Alzette floodplain in Luxembourg. Methods: Competitive response and importance of competition were assessed on seven meadow species differing in their tolerance to flooding. Species were cultured in monocultures and in mixtures, in three water treatments reflecting the wet, the middle and the dry end of a natural flooding gradient. We developed two models based on a multiple regression in order to express each component of competition as a function of the neighbour biomass. Results: Five species showed variations in their competitive response across water treatments; however, these species achieved either their highest or their worst competitive response in their optimal water treatment (i.e. the treatment in which the species had the highest biomass in monoculture). Competition was more important for the flood‐tolerant species in the dry treatment than for the flood‐intolerant species in the wet treatment. Conclusions: 1. Variations in species competitive responses along flooding gradients may be the result of either an amplified effect between competition and hydrological stresses, or a hierarchical effect of stress over competition. 2. The role of competition is more important in constraining the upper distribution limits of the flood‐tolerant species than the lower limits of the flood‐intolerant species along flooding gradients. 相似文献
276.
The interplay between storms and sea level rise, and between ecology and sediment transport governs the behavior of rapidly evolving coastal ecosystems such as marshes and barrier islands. Sediment deposition during hurricanes is thought to increase the resilience of salt marshes to sea level rise by increasing soil elevation and vegetation productivity. We use mesocosms to simulate burial of Spartina alterniflora during hurricane‐induced overwash events of various thickness (0–60 cm), and find that adventitious root growth within the overwash sediment layer increases total biomass by up to 120%. In contrast to most previous work illustrating a simple positive relationship between burial depth and vegetation productivity, our work reveals an optimum burial depth (5–10 cm) beyond which burial leads to plant mortality. The optimum burial depth increases with flooding frequency, indicating that storm deposition ameliorates flooding stress, and that its impact on productivity will become more important under accelerated sea level rise. Our results suggest that frequent, low magnitude storm events associated with naturally migrating islands may increase the resilience of marshes to sea level rise, and in turn, slow island migration rates. Synthesis: We find that burial deeper than the optimum results in reduced growth or mortality of marsh vegetation, which suggests that future increases in overwash thickness associated with more intense storms and artificial heightening of dunes could lead to less resilient marshes. 相似文献
277.
278.
不同胁迫预处理对水稻幼苗抗冷性和抗旱性的影响 总被引:6,自引:1,他引:6
水稻幼苗干旱预处理8小时后,转入低温(8~10℃),其抗冷性比未处理的高。0.1mol/L Nacl溶液盐预处理24小时,也提高水稻幼苗的抗冷性。低温3天,水稻幼苗叶片积累大量的脱落酸,此时将幼苗转至干旱环境下,抗旱性也大大提高。这说明水稻幼苗具有交叉适应能力,而脱落酸在交叉适应中起着重要的调节作用。 相似文献
279.
Common mechanisms plants use to translate the external stimuli into cellular responses are the activation of mitogen-activated protein kinase (MAPK) cascade. These MAPK cascades are highly conserved in eukaryotes and consist of three subsequently acting protein kinases, MAP kinase kinase kinase (MAPKKK), MAP kinase kinase (MAPKK) and MAP kinase (MAPK) which are linked in various ways with upstream receptors and downstream targets. Plant MAPK cascades regulate numerous processes, including various environmental stresses, hormones, cell division and developmental processes. The number of MAPKKs in Arabidopsis and rice is almost half the number of MAPKs pointing important role of MAPKKs in integrating signals from several MAPKKKs and transducing signals to various MAPKs. The cross talks between different signal transduction pathways are concentrated at the level of MAPKK in the MAPK cascade. Here we discussed the insights into MAPKK mediated response to environmental stresses and in plant growth and development. 相似文献
280.