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41.
42.
Tropical ferns are characterized by a high diversity of plant life forms, yet there have been few large-scale studies on the
functional ecology of these different forms. We examined epiphytic, hemiepiphytic, and terrestrial ferns, and asked whether
there are differences in the mineral nutrition and water relations across different growth forms of a diverse assemblage of
species. We measured specific leaf area, leaf nitrogen concentrations, and natural abundance of the stable isotopes δ15N and δ13C of 48 fern species from 36 genera across a wide range of habitats at La Selva Biological Station in Costa Rica. We found
that epiphytes were significantly different in all measured variables from hemiepiphytic and terrestrial species, and that
terrestrial and soil-rooted hemiepiphytes were indistinguishable in all variables excluding SLW. A multivariate analysis revealed
that aspects of N nutrition were the most reliable at separating epiphytic species from other life forms. Our study demonstrates
that the natural abundance of both C and N as well as N relations and leaf morphology are useful when segregating different
plant life forms, and that the N cycle of epiphytic and terrestrial habitats function independently from each other. 相似文献
43.
44.
A survey of trace elements in pteridophytes 总被引:2,自引:0,他引:2
Concentration of 11 trace elements (Ca, Sc, Cr, Fe, Co, Zn, Rb, Cs, Ba, La, and Ce) in 96 pteridophytes (fern and fern ally
species) was determined by instrumental neutron activation analysis to evaluate a concentration range for each element and
also to find species characteristic in the uptake of trace elements. Asplenium trichomanes was found to accumulate Sc, Cr, and Co to the highest concentrations among 96 pteridophytes. The highest concentration of
Ca and Zn was observed for Asplenium obscurum. The other Pteridophytes exhibited only one element whose concentration was the highest. A positive correlation was found
between the concentrations of Fe and Sc, and also between the concentrations of Cr and Co. The remarkable accumulation of
lanthanides (La and Ce) was observed mainly in diversifying genera (Polystichum and Dryopteris in Dryopteridaceae, Diplazium in Woodsiaceae, and Asplenium in Aspleniaceae). 相似文献
45.
Using freeze-fracture electron microscopy we have examined the morphology of the plasma membrane and the cell wall of single-celled protonemal filaments of the fern Adiantum capillus-veneris grown under continuous red light. The surface of the protonemal cell wall is completely covered by a multilayered, lipid-like coat, probably consisting of cuticular waxes. The rhizoid seems to lack this type of coat. The cell walls of the protonemata contain 8-nm thick, randomly oriented fibrils. In rapidly growing protonemata the P-face of the plasma membrane contains both randomly distributed particles and distinct particle rosettes. The rosettes consist of six 8–9-nm-wide particles in a ring-like configaration and have an outer diameter of 24 nm. They closely resemble the particle rosettes seen on the P-face of the plasma membrane of green algae and of higher plants, which recently have been implicated in the synthesis of cellulose fibrils. Within 20 m from the tip of the protonemata, and coinciding with the region of maximal cell-wall growth and expansion and thus cellulose-fibril synthesis, the greatest density of rosettes (20/m2) is observed. Beyond 20 m from the tip this number drops rapidly to near zero at 50 m. The rosettes have a tendency to form small, irregular clusters, but only very rarely are three or more rosettes found in a row or in a geometrical pattern. Our measurements of the size and the density of the randomly distributed plasma membrane particles indicate that the tip region must be specialized with respect to other plasma-membrane activities as well. Thus the tip region contains not only the highest density of randomly destributed intramembrane particles, but also particles of different sizes than those found elsewhere in the plasma membrane. 相似文献
46.
Apical cells on the verge of dividing, or having recently formed a new segment, or actually dividing, are not uncommonly encountered in bryophytes and pteridophytes. This is interpreted as evidence for the classical concept of active apical segmentation in these plants (versus the concept of a quiescent apical cell). In certain species a polarized organization of the cytoplasm of the dividing apical cells is identifiable. 相似文献
47.
48.
This article delineates the compositional regions present in the Iberian–Balearic fern flora and compares these regions to
previously proposed biogeographic units. It also assesses the extent to which environmental variables could explain the regions
and the fern species richness gradients found within them. A combination of 40 previously published and new maps were used
to compile the distribution of 123 pteridophytes on a 50 × 50 km UTM grid. Cluster analysis of the resulting 257 squares was
used to classify 10 regions based on fern species assemblages. Discriminant function analysis identified the environmental
variables that best explained these fern composition regions. Using generalized linear models; the number of species in each
square was regressed against topography, climate, geology, environmental diversity, land use and spatial variables within
each region. Two main latitudinal pteridophyte zones can be recognized in the Iberian Peninsula. These two zones are longitudinally
subdivided into two sub zones. The 10 regions established significantly differ both in species richness and influential environmental
variables. Climatic variables discriminate the most among regions, followed by topography, heterogeneity and geology. Pteridophyte
richness varies, with richer areas being located along the coast and the main mountain ranges and the poorest areas being
in the central plateaus and some north eastern and south western river basins. Species richness variation in Iberia is positively
correlated with altitude range, precipitation, maximum altitude and area with siliceous soils. It is negatively correlated
with the total annual days of sun, however. The fact that species richness is explained by different variables within each
of the 10 regions indicates that the specific factors determining the spatial distribution of species richness vary from region
to region. Some coastal regions are poorly explained by the model, and display a negative correlation with the selected causal
factors. This finding suggests that persistent historic effects might play a local role in determining species assemblages
in these regions.
An erratum to this article can be found at 相似文献
49.
Marcelo Guerra Santos Gabriela Fraga Porto Isabella Rodrigues Lancellotti Rodrigo M. Feitosa 《Revista Brasileira de Entomologia》2019,63(2):101-103
Galls are neoformed plant structures created by cell hyperplasia and hypertrophy induced by a number of organisms, especially insects. After adult insects hatch, senescent galls may remain on the host plant and be occupied by a succession of fauna, the most important and dominant being ants. This study aimed at characterizing the ant fauna successor of stem galls induced by microlepidoptera in Microgramma squamulosa (Kaulf.) de la Sota (Polypodiaceae). Four collections were carried out in the municipality of Nova Friburgo, Rio de Janeiro state, Brazil. The galls were packed in plastic bags and taken to the laboratory. Ants were euthanized and conserved in 70° GL alcohol and later identified. A total of 49 stem galls were collected and analyzed, 15 containing microlepidoptera galler larvae, one a parasitoid wasp and 33 without the microlepidoptera or parasitoid (67%). Twelve of these galls (39%) contained ants. Six ant species were recorded (Camponotus crassus, Crematogaster curvispinosa, Crematogaster sericea, Procryptocerus sampaioi, Tapinoma atriceps, and Wasmannia auropunctata), all native to Brazil. Ant occupation in M. squamulosa seems to be associated with senescent galls due to hatching of the galler insect, which leaves a hole that allows ants to colonize it, in other words, an opportunistic domatia. Senescent galls resulting from the death of galler insects do not seem to facilitate ant occupation. 相似文献
50.
Yosuke Matsuda Fumie Murahashi Mai Kimoto Ken-ichi Nakanishi Shin-ichiro Ito 《Mycoscience》2005,46(4):261-264
To investigate the occurrence of arbuscular mycorrhizas (AM) and their morphological types, four Athyrium yokoscense and five A. niponicum individuals were collected at a lead-contaminated site. Three of the A. yokoscense and four of the A. niponicum formed AM structures. However, the percentage of AM formation within both species differed significantly among individuals. Morphological types of most AM structures were the Paris-type, except for one A. yokoscense that formed both Paris-type and Arum-type-like structures in different parts of the same root section. These results demonstrate that the two Athyrium species form AM associations in lead-contaminated soil. 相似文献