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131.
132.
Abstract: On the basis of six articulated individuals from the middle to late Albian lithographic limestone at Tlayúa near Tepexi de Rodríguez (Puebla, Mexico), a new species of ophiuroid, Ophiactis applegatei , is described. The material adds to the rather poor record of Early Cretaceous brittlestars and represents the oldest known member of the family Ophiactidae, being based on well-preserved and articulated specimens and thus reasonably well defined morphologically. The rarity of ophiuroids, their complete preservation as well as the unnatural contortions of their arms suggest these specimens to be allochthonous, having been transported into a hostile environment where burial was rapid. 相似文献
133.
PEDRO JORDANO 《Ibis》1987,129(S1):175-189
Fruit consumption was assessed in six species of Sylvia warblers and compared to variation in external morphology and digestive system. Variation in the use of fruit was determined primarily by external morphology (body-size, gape-width and hindlimb characteristics). Variation in digestive traits (intestine-length, gizzard and liver-weight) did not account for a significant fraction of variation in frugivory across species. Relative to other non-frugivorous Muscicapidae, Sylvia spp. exhibit digestive adaptations specific to fruit processing; however, variation in external morphology constrains the degree of dependence on fruit within the genus. 相似文献
134.
Fire ecology has been hindered by the lack of comparable, affordable protocols to quantify the flammability of whole plants over large numbers of species. We describe a low‐tech device that can be carried to the field and that allows highly standardized measurement of the flammability of whole individuals or portions up to 70 cm long. We illustrate its potential with results for 34 species belonging to different growth forms from central Argentina. The device consists of an 85 × 60 cm half‐cut metallic barrel placed horizontally and mounted on a removable metallic structure. It contains three parallel burners, a grill with an attached gauging thermometer and a blowtorch. Burners and blowtorch are connected to a propane–butane gas cylinder. Plant samples are placed on the grill and preheated with the burners for 2 min at 150°C. They are then ignited for 10 s with the blowtorch while the burners are kept on. Four parameters are measured for each sample: maximum temperature reached, burning time, burnt length and burnt biomass percentage. These parameters are used to construct a compound index of flammability for each sample that ranges between 0 (no flammability) and around 3 (maximum flammability). We obtained a wide range of values for flammability and all its components. Most of this variability was accounted for by differences between growth forms and species, rather than by differences at the level of replicates. This suggests that the device and protocol are sensitive enough to detect flammability differences among plants with different functional traits, and at the same time robust enough to produce consistent results among samples with similar traits. A major advantage is that plant architecture is kept almost intact, providing a flammability measure much closer to that of whole individuals in the field than those obtained by other standard protocols in use. The device and protocol presented here should facilitate the acquisition of comparable flammability data over large numbers of species from different floras and ecosystems, potentially contributing to several fields of research, such as functional ecology, evolutionary ecology and vegetation‐atmosphere modelling. 相似文献
135.
Petunia axillaris plants were grown under white light (photoperiod10 h). Pulses of end-of-day far-red light, but not red lightat the end of the day slowed down the accumulation of chlorophyllin expanding, greening leaves and reduced chlorophyll contentin mature leaves. The chlorophyll a / b ratio was unaffected.Low phytochrome photoequilibria reduced chlorophyll contentin mature leaves without affecting leaf area or d. wt. Thiseffect occurred even before senescence was triggered in thecontrol plants having high phytochrome photoequilibria 相似文献
136.
GUSTAVO YA
EZ-OCAMPO MARTHA E. MORA-HERRERA ARNOLDO WONG-VILLARREAL DENISSE M. DE LA PAZ-OSORIO NADIA DE LA PORTILLA-L
PEZ JORGE LUGO ROCIO VACA-PAULÍN PEDRO DEL GUILA 《Polish journal of microbiology》2020,69(3):357
The capacity of four bacterial strains isolated from productive soil potato fields to solubilize tricalcium phosphate on Pikovskaya agar or in a liquid medium was evaluated. A bacterial strain was selected to evaluate in vitro capacity of plant-growth promotion on Solanum tuberosum L. culture. Bacterial strain A3 showed the highest value of phosphate solubilization, reaching a 20 mm-diameter halo and a concentration of 350 mg/l on agar and in a liquid medium, respectively. Bacterial strain A3 was identified by 16S rDNA analysis as Bacillus pumilus with 98% identity; therefore, it is the first report for Bacillus pumilus as phosphate solubilizer. Plant-growth promotion assayed by in vitro culture of potato microplants showed that the addition of bacterial strain A3 increased root and stems length after 28 days. It significantly increased stem length by 79.3%, and duplicated the fresh weight of control microplants. In this paper, results reported regarding phosphorus solubilization and growth promotion under in vitro conditions represent a step forward in the use of innocuous bacterial strain biofertilizer on potato field cultures.Key words: Bacillus sp., phosphorus soluble, Pikovskaya agar, potato rhizosphere, plant growth promoting rhizobacteria 相似文献
137.
138.
EUGENIA ELISABETH MONTIEL MARIA INMACULADA MANRIQUE‐POYATO SONIA M. ROCHA‐SÁNCHEZ MARIA DOLORES LÓPEZ‐LEÓN JOSEFA CABRERO FRANCISCO PERFECTTI JUAN PEDRO M. CAMACHO 《Physiological Entomology》2012,37(2):145-152
The nucleolus constitutes a cytologically visible phenotype for ribosomal DNA (rDNA). Nucleolar size, as determined by silver staining, is a good indicator of cell proliferation rate and biosynthetic activity. Nevertheless, the relationship between rDNA content and sexual dimorphism for nucleolar size is not well documented. In the present study, the impact of sex and ploidy level on nucleolar size is investigated in three haplo/diploid and three diplo/diploid species of insect. Nucleolar sizes are found to be proportional to ploidy level in the haplo/diploid hymenopterans Trypoxylon albitarse and Nasonia vitripennis. Conversely, in the ant Messor barbarus, nucleolar sizes are larger in haploid males (winged) than diploid females (apterous). Among the diplo/diploid species, evidence for gene dosage compensation on nucleolar activity is suggested by the absence of sex differences in Drosophila simulans, a species in which rDNA is limited to the X chromosome. By contrast, in the grasshopper Stenobothrus festivus, another species with rRNA genes restricted to the X chromosome, the size of the nucleolus is significantly larger in females than in males. Additionally, in the grasshopper Chorthippus parallelus, where rDNA is distributed evenly on several autosomes of males and females, the females also show larger nucleoli than males. In both grasshopper species, the magnitude of the female/male ratio for nucleolus area is very similar to the body size ratio, suggesting that body size, as well as sex, ploidy, gene dosage and physiological activity, may be an important determinant of nucleolus area. 相似文献
139.
PEDRO CÓZAR DANIEL VACHARD 《Lethaia: An International Journal of Palaeontology and Stratigraphy》2004,37(4):351-363
Well‐preserved specimens of Calcifolium ? punctatum Maslov from the Guadiato area (Spain) show a great adaptability to environmental modifications. Six morphotypes are recognized: flabellum‐shaped cups, massive erect cups, stockade cups, crustose growth, petals and inter‐cup segments. These morphologies are an adaptative response to fluctuation of the following factors: substratum, light/turbidity/depth, competition for space, influx of micrite/rate of sedimentation, hydrodynamic energy and bioturbation. 相似文献
140.
APARICIO-TEJO PEDRO M.; SANCHEZ-DIAZ MANUEL F.; PENA JOSE I. 《Journal of experimental botany》1980,31(3):839-843
The relationship between transpiration measured gravimetrically,a generalized transpiration equation, and the ratio VPD/rleafwas investigated in Trifolium repens plants subjected to varyingwater potentials. Dawn leaf water potential was measured witha pressure chamber, leaf diffusion resistance with a diffusionporometer, leaf temperatures with a thermistor, and relativehumidity with an aspirated psychrometer. During drought transpirationrates determined by both methods were quite similar particularlyat the lowest water potentials. After rewatering calculatedrates were somewhat higher than measured ones. It is concludedthat transpiration calculated by the indirect method is a usefuland reasonable estimate of transpiration for single plants undervarying water potentials. 相似文献