全文获取类型
收费全文 | 64篇 |
免费 | 4篇 |
出版年
2022年 | 1篇 |
2021年 | 2篇 |
2020年 | 2篇 |
2017年 | 3篇 |
2016年 | 2篇 |
2013年 | 4篇 |
2012年 | 1篇 |
2011年 | 2篇 |
2009年 | 4篇 |
2008年 | 5篇 |
2007年 | 4篇 |
2006年 | 5篇 |
2005年 | 3篇 |
2004年 | 3篇 |
2003年 | 1篇 |
2002年 | 3篇 |
2001年 | 4篇 |
2000年 | 1篇 |
1999年 | 1篇 |
1998年 | 3篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1993年 | 2篇 |
1992年 | 1篇 |
1990年 | 1篇 |
1987年 | 2篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1976年 | 1篇 |
排序方式: 共有68条查询结果,搜索用时 15 毫秒
61.
Foliar δ15N, %N and %P in the dominant woody and herbaceous species across nutrient gradients in New Zealand restiad (family Restionaceae)
raised bogs revealed marked differences in plant δ15N correlations with P. The two heath shrubs, Leptospermum scoparium (Myrtaceae) and Dracophyllum scoparium (Epacridaceae), showed considerable isotopic variation (−2.03 to −15.55‰, and −0.39 to −12.06‰, respectively) across the
bogs, with foliar δ15N strongly and positively correlated with P concentrations in foliage and peat, and negatively correlated with foliar N:P
ratios. For L. scoparium, the isotopic gradient was not linked to ectomycorrhizal (ECM) fractionation as ECMs occurred only on higher nutrient marginal
peats where 15N depletion was least. In strong contrast, restiad species (Empodisma minus Sporadanthus ferrugineus, S. traversii) showed little isotopic variation across the same nutrient gradients. Empodisma minus and S. traversii had δ15N levels consistently around 0‰ (means of −0.12‰ and +0.15‰ respectively), and S. ferrugineus, which co-habited with E. minus, was more depleted (mean −4.97‰). The isotopic differences between heath shrubs and restiads were similar in floristically
dissimilar bogs and may be linked to contrasting nutrient demands, acquisition mechanisms, and root morphology. Leptospermum scoparium shrubs on low nutrient peats were stunted, with low tissue P concentrations, and high N:P ratios, suggesting they were P-limited,
which was probably exacerbated by markedly reduced mycorrhizal colonisations. The coupling of δ15N depletion and %P in heath shrubs suggests that N fractionation is promoted by P limitation. In contrast, the constancy in
δ15N of the restiad species through the N and P gradients suggests that these are not suffering from P limitation. 相似文献
62.
With a career stretching from the 1960s, Roger Good clocked up over 50 years’ experience in restoring alpine ecosystems, particularly bogs and fens. This interview (recorded not long before Roger's untimely death in 2015) shows how the evolving approaches to restoration in Australia's Snowy Mountains mirror the evolving broad discipline of restoration. 相似文献
63.
64.
Terence J Painter 《Carbohydrate polymers》1998,36(4):335-347
Well-preserved human bodies more than 2000 years old have been found in peat bogs derived mainly from sphagnum mosses. Preservation is correlated with the occurrence of -keto-carboxylate groups in a glycuronoglycan (‘sphagnan') that comprises 60% of the holocellulose in the hyaline cell walls of the mosses [Painter (1991b). Carbohydr. Polym., 15, 123–142]. There is now renewed interest in other biodegradable materials that have been found preserved in peat, including carcasses of domestic animals, loaves of bread, dried fruits, berries, and kegs of butter or cheese up to 1800 years old. This review attempts to correlate these examples of fortuitous preservation in peat with other, more familiar methods of food preservation that depend in the first instance upon the condensation of highly reactive carbonyl compounds with primary amino-groups or ammonia. The Maillard reaction inhibits microbial growth by sequestering ammonia, aminoacids and peptides, while the brown, polymeric end-products (‘melanoidins') inhibit by cross-linking polypeptide chains and sequestering essential, multivalent metal cations. These reactions could find broader or entirely new applications in food preservation. 相似文献
65.
Effects of water level and temperature on performance
of four <Emphasis Type="Italic">Sphagnum</Emphasis> mosses 总被引:1,自引:0,他引:1
Bjorn J.M. Robroek Juul Limpens Angela Breeuwer Matthijs G.C. Schouten 《Plant Ecology》2007,190(1):97-107
To evaluate the effects of changes in water level and temperatures on performance of four Sphagnum mosses, S. magellanicum, S. rubellum, S. imbricatum and S. fuscum were grown at two water levels, −5 cm and −15 cm, and at two temperatures, 15°C and 20°C. These species differ in their
position along the microtopographical gradient and in their geographical distribution. Height increment, subcapitulum bulk
density, biomass production, capitulum water content and cumulative evaporation were measured. Height increment and biomass
production of S. magellanicum was lower at low water table than at high water table, whereas height increment and biomass production of S. rubellum, S. imbricatum and S. fuscum were unaffected. Height increment of S. magellanicum, S. rubellum and S. imbricatum was higher at high temperature than at low temperature. Biomass production of only S. magellanicum and S. rubellum was higher at high temperature than at low temperature, corresponding with their more southern distribution. Cumulative evaporation
of S. magellanicum and S. rubellum was lower at low water table and could be explained by hampered water transport towards the capitula. We conclude that changes
in water table and temperature may alter the Sphagnum composition on raised bogs, which may result in changes to important ecosystem processes. Therefore, it is important that
species composition and changes therein are taken into account when evaluating global change effects on raised bog ecosystems. 相似文献
66.
The microbial population of sphagnum peat bogs of northern Russia was analyzed with respect to the presence and cell numbers of representatives of particular phylogenetic groups of prokaryotes by means of in situ hybridization with fluorescently labeled group-specific rRNA-targeted oligonucleotide probes with broad detection spectra. The total number of cells that hybridized with universal Archaea- and Bacteria-specific probes varied, in peat samples of different bogs, from 45 to 83% of the number of cells revealed by DAPI staining. Down the bog profiles, the total number of prokaryotes and the fraction of archaea among them increased. Application of a set of oligonucleotide probes showed that the number of microorganisms belonging to such phylogenetic lineages of the domain Bacteria as the phyla Proteobacteria, Bacteroidetes, Actinobacteria, Firmicutes, Acidobacteria, and Planctomycetes constituted, in total, 14.0–26.5% of the number of eubacteria detected in the samples. Among the bacteria identified in the peat samples, the most abundant were representatives of the classes Alphaproteobacteria and Betaproteobacteria and the phyla Acidobacteria, Bacteroidetes, and Actinobacteria. 相似文献
67.
Morphological disparity has increasingly been used as an alternative measure of biological diversity based on the shape features
of organisms. In this study, we investigated the species diversity and morphological disparity of benthic Desmidiales in Central
European peatland pools. The shape features of cells were determined using the 3-D elliptical Fourier analysis of their frontal
and lateral views. The resulting morphospace was used to calculate the contributions of localities and species to the morphological
variation. In addition, the disparity of samples and their average cell complexity (indicating intricacy of cell shapes) was
evaluated. These data were related to species diversity data and to the abiotic factors. Species diversity was positively
correlated with pH and conductivity. The low-pH localities generally supported a more variable species composition than did
slightly acidic to neutral localities. Conversely, the total nitrogen concentrations of these areas negatively correlated
with species diversity. Interestingly, partial morphological disparity (measuring the contribution of a sample to the overall
morphological variation) did not correlate with species diversity. On the contrary, several mountain peat bog localities had
high disparity values, irrespective of their rather low species diversity. In addition, several samples from minerotrophic
fens with high diversity had average or low values of partial morphological disparity. These results indicate the relative
importance of mountain peat bogs for the total morphological diversity of Desmidiales within the region that could not be ascertained solely from species diversity data. The inner morphological disparity of
samples was highly correlated with their species diversity. Species of the genus Micrasterias, Hyalotheca dissiliens and Desmidium species had the highest partial morphological disparity, thus indicating their marginal position within the morphospace.
Micrasterias and Euastrum species had the highest complexity values. The average cell complexity of individual samples did not correlate with their
diversity or disparity; however, it was positively correlated with the levels of total nitrogen and phosphorus, and illustrates
a pattern different from that arrived at by species diversity data.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.
Handling editor: J. Padisak 相似文献
68.
This paper summarizes expected changes in hydrology, chemistry and biota of Dutch peatlands (bogs, fens and moorland pools) caused by climatic changes resulting from the Greenhouse Effect. Special attention is paid to the interaction with atmospheric acid deposition. In both bogs and moorland pools prolonged drought periods may cause deleterious effects on biota because of the release of atmospherically-derived reduced sulphur compounds. In fenlands negative changes will be caused by eutrophication due to increased supply of allochtonous water. Long-term water and nutrient budgets are needed, along with better predictions of expected climate changes, to develop models of changes in hydrology, chemistry and biota of peatlands. 相似文献