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排序方式: 共有103条查询结果,搜索用时 15 毫秒
21.
BACKGROUND AND AIMS: Species' 2C-values (mass of DNA in G(1) phase 2n nuclei) vary by at least four orders of magnitude among seed plants. The 2C-value has been shown to be co-ordinated with a number of other species traits, and with environmental variables. A prediction that species 2C-values are negatively related to leaf life span (LL) and leaf mass per area (LMA) is tested. These leaf traits are components of a major dimension of ecological variation among plant species. METHODS: Flow cytometry was used to measure the 2C-values for 41 Australian seed plant species, 40 of which were new to the literature. Where possible, LL and LMA data from the global literature were combined with 2C-values from our data set and online C-value databases. KEY RESULTS: Across all species, weak positive relationships were found between 2C-values and both LL and LMA; however, these did not reflect the relationships within either angiosperms or gymnosperms. Across 59 angiosperm species, there were weak negative relationships between 2C-values and both LL (r2 = 0.13, P = 0.005) and LMA (r2 = 0.15, P = 0.002). These relationships were the result of shifts to longer LL and greater LMA in woody compared with herbaceous growth forms, with no relationships present within growth forms. It was not possible to explain a positive relationship between 2C-values and LMA (r2 = 0.30, P = 0.024) across 17 gymnosperm species. The 2C-value was not related to LL or LMA either across species within orders (except for LMA among Pinales), or as radiation divergences in a model phylogeny. CONCLUSIONS: Gymnosperms appear to vary along a spectrum different from angiosperms. Among angiosperms, weak negative cross-species relationships were associated with growth form differences, and traced to a few divergences deep in the model phylogeny. These results suggest that among angiosperms, nuclear DNA content and leaf strategy are unrelated. 相似文献
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Weak coordination among petiole,leaf, vein,and gas‐exchange traits across Australian angiosperm species and its possible implications
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Sean M. Gleason Chris J. Blackman Yvonne Chang Alicia M. Cook Claire A. Laws Mark Westoby 《Ecology and evolution》2016,6(1):267-278
Close coordination between leaf gas exchange and maximal hydraulic supply has been reported across diverse plant life forms. However, it has also been suggested that this relationship may become weak or break down completely within the angiosperms. We examined coordination between hydraulic, leaf vein, and gas‐exchange traits across a diverse group of 35 evergreen Australian angiosperms, spanning a large range in leaf structure and habitat. Leaf‐specific conductance was calculated from petiole vessel anatomy and was also measured directly using the rehydration technique. Leaf vein density (thought to be a determinant of gas exchange rate), maximal stomatal conductance, and net CO2 assimilation rate were also measured for most species (n = 19–35). Vein density was not correlated with leaf‐specific conductance (either calculated or measured), stomatal conductance, nor maximal net CO2 assimilation, with r2 values ranging from 0.00 to 0.11, P values from 0.909 to 0.102, and n values from 19 to 35 in all cases. Leaf‐specific conductance calculated from petiole anatomy was weakly correlated with maximal stomatal conductance (r2 = 0.16; P = 0.022; n = 32), whereas the direct measurement of leaf‐specific conductance was weakly correlated with net maximal CO2 assimilation (r2 = 0.21; P = 0.005; n = 35). Calculated leaf‐specific conductance, xylem ultrastructure, and leaf vein density do not appear to be reliable proxy traits for assessing differences in rates of gas exchange or growth across diverse sets of evergreen angiosperms. 相似文献
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In sclerophylls, photosynthesis is particularly strongly limited by mesophyll diffusion resistance from substomatal cavities to chloroplasts (r (m)), but the controls on diffusion limits by integral leaf variables such as leaf thickness, density, and dry mass per unit area and by the individual steps along the diffusion pathway are imperfectly understood. To gain insight into the determinants of r (m) in leaves with varying structure, the full CO(2) physical diffusion pathway was analysed in 32 Australian species sampled from sites contrasting in soil nutrients and rainfall, and having leaf structures from mesophytic to strongly sclerophyllous. r (m) was estimated based on combined measurements of gas exchange and chlorophyll fluorescence. In addition, r (m) was modelled on the basis of detailed anatomical measurements to separate the importance of different serial resistances affecting CO(2) diffusion into chloroplasts. The strongest sources of variation in r (m) were S (c)/S, the exposed surface area of chloroplasts per unit leaf area, and mesophyll cell wall thickness, t (cw). The strong correlation of r (m) with t (cw) could not be explained by cell wall thickness alone, and most likely arose from a further effect of cell wall porosity. The CO(2) drawdown from intercellular spaces to chloroplasts was positively correlated with t (cw), suggesting enhanced diffusional limitations in leaves with thicker cell walls. Leaf thickness and density were poorly correlated with S (c)/S, indicating that widely varying combinations of leaf anatomical traits occur at given values of leaf integrated traits, and suggesting that detailed anatomical studies are needed to predict r (m) for any given species. 相似文献
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Do small leaves expand faster than large leaves,and do shorter expansion times reduce herbivore damage? 总被引:5,自引:0,他引:5
Leaves are most vulnerable to herbivory during expansion. We hypothesised that one factor favouring small leaves could be that smaller-leaved species have shorter expansion times and are therefore exposed to high levels of herbivory for a shorter period than large leaves. In order to test this hypothesis, leaf expansion time and leaf area loss were measured for 51 species from Sydney, Australia. Strong positive correlations were found between leaf length and area and leaf expansion time, confirming that small leaves do expand in a shorter time than large leaves. The amount of leaf area lost was highly variable (from 0.5 to 90% of total leaf area), but was significantly related to both leaf expansion time and log leaf area. The amount of leaf area lost was not significantly correlated with specific leaf area nor with the presence of distasteful substances in the leaves, but was lower on species with hairy expanding leaves. 相似文献
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This communication focuses on respected older womens’ (‘Aunties’) experiences of climate and other environmental change observed
on Australia’s Erub Island in the Torres Strait. By documenting these experiences, we explore the gendered nature of climate
change, and provide new perspectives on how these environmental impacts are experienced, enacted and responded to. The way
these adverse changes affect people and places is bound up with numerous constructions of difference, including gender. The
responses of the Aunties interviewed to climate change impacts revealed Solastalgia; feelings of sadness, worry, fear and
distress, along with a declining sense of self, belonging and familiarity. 相似文献
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Shifts in trait-combinations along rainfall and phosphorus gradients 总被引:10,自引:0,他引:10
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