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131.
Stuart E. Bunn 《Hydrobiologia》1988,162(3):201-210
Seasonal differences in the processing of jarrah (Eucalyptus marginata) leaves were examined in a small forest stream of the Darling Range, Western Australia. Processing rates in both summer and winter were very low, placing this species in the slow category (k < 0.005) of Petersen & Cummins (1974).Macroinvertebrates did not contribute to the processing of jarrah leaves during summer and autumn, coincident with the period of peak litter fall. The low quality of detritus entering the streams, and possibly some adverse interactions with the physical and chemical environment, inhibits processing during the summer months. As a consequence, a significant proportion of the coarse-particle detritus entering these streams may be exported unprocessed at the onset of high winter flows.In contrast with previous studies, jarrah leaves were processed at a faster rate during winter than summer. This seasonal difference can, in part, be attributed to the increased density and proportion of shredders at this time. Despite this, the processing of jarrah leaves during winter was very slow and must reflect the poor quality of this detritus as food for invertebrate consumers. 相似文献
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We report the vegetative proliferation and new phenomenon of “secondary proliferated inflorescences” in the grass Ischaemum barbatum Retz, as determined by anatomical analysis of prepared sections of inflorescences. Leaves and shoots could be developed from the original spikelets of inflorescences and plantlets developed when these shoots were transplanted to moist soil. “Secondary proliferated inflorescences” is the first name here because some inflorescences that developed inadequacy are grown from the spikelet on the mother inflorescence. Our investigation showed that this form of vegetative proliferation and secondary proliferated inflorescences development of I. barbatum has arisen following late autumn fires of the previous year. It is suggested that the sudden onset of a fire could lead to a hormone imbalance or a chemical induction, which results in ephemeral vegetative proliferation even secondary proliferated inflorescences development in wild populations.(Author for correspondence. Tel: +86 (0)20 3725 2993; E-mail: magh@scib.ac.cn) 相似文献
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Andrew G. Bunn 《Dendrochronologia》2010,28(4):251-258
I demonstrate new functionality for the Dendrochronology Program Library in R (dplR) that allows for flexible statistical crossdating of tree-ring data. Using a well-dated ring-width file, I give examples of how dplR can be used to examine correlations between each series and a master chronology according to overlapping time periods (segments) specified by the user; examine moving correlations of suspect series; and compute cross-correlation functions to identify specific dating issues. I also show how automatically generated skeleton plots can be used to visually crossdate. Much of the terminology and approach used for crossdating in dplR will be familiar to users of COFECHA. 相似文献
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Shahab Nikabadi Eric Bunn Jason Stevens Belinda Newman Shane R. Turner Kingsley W. Dixon 《Plant Cell, Tissue and Organ Culture》2014,118(3):559-569
We report an investigation into the impact of temperature and illumination on in vitro symbiotic and asymbiotic germination of the threatened taxon Caladenia huegelii, and three other orchid spp. namely—Caladenia latifolia, Microtis media and Pterostylis sanguinea, all species from south-west Western Australia, a recognized biodiversity hotspot. High symbiotic germination on oatmeal agar (OMA + fungal symbionts specific to each species) was recorded in three species in continuous dark incubation i.e. C. huegelii seeds (98 % germination at 25 °C), and M. media and P. sanguinea (93 and 98 % respectively at 20 °C). Highest symbiotic germination for C. latifolia (100 %) was observed at 15 and 20 °C under light treatment (12/12 h light/dark). Low temperature incubation (10 °C) significantly suppressed symbiotic germination/development of seedlings across all species. Asymbiotic media treatments assessed (OMA minus fungal symbionts, Pa5 and ½ MS), failed to stimulate any germination with C. latifolia seeds at 20 °C in either light or dark treatments after an 8 week incubation period. Seeds of M. media sown onto ½ MS medium resulted in higher germination in all developmental stages (3–5) in dark treatment than OMA and Pa5. Seeds of P. sanguinea sown onto ½ MS medium resulted in higher overall germination in all developmental stages (3–5) in light and dark incubation compared to OMA and Pa5. OMA supported the highest asymbiotic germination (100 %) in both light and dark incubation with M. media (only to stage 3) but did not support germination and development with other spp. tested. Caladenia huegelii seeds reached developmental Stage 3 (i.e. germinated), but only on Pa5 medium and only at a relatively low rate in either light (2.6 %) or dark (2.1 %). Germination was higher and development of seedlings faster overall in all test species in symbiotic compared with asymbiotic media treatments. P. sanguinea seeds demonstrated the best response (among species tested) to asymbiotic germination on ½ MS with 40–53 % of germinated seeds spread over developmental stages 3–5 in light or dark incubation (at 20 °C) respectively. Illumination had no effect on fungal symbiont growth across all species, however incubation temperature treatments (10, 15, 20 and 25 °C) affected fungal growth rate. Growth of the fungal symbionts of C. huegelii, M. media and C. latifolia demonstrated significantly lower activity at 10 °C, but the cumulative radial growth rate of the P. sanguinea fungal symbiont reached 64 cm2 after only 2 weeks at all temperatures tested, including 10 °C. The study highlights differences in symbiotic and aysmbiotic germination and early protocorm development in vitro between co-occurring herbaceous terrestrial Australian orchid taxa in response to variations in basal media, temperature and light. 相似文献
139.
Evidence of Dichogamy in Santalum album L. 总被引:1,自引:0,他引:1
Guo-Hua Ma Eric Bunn Jing-Feng Zhang Guo-Jiang Wu 《植物学报(英文版)》2006,48(3):300-306
Flowering, fruit set, embryological development, and pollination trials were Investigated In Santslum album L. Each ovary may have three to four ovules. Mlcrosporogenesls and megasporogenesls In the same flower were synchronized at the earlier stages of flower development. However, at anthesls, when pollen was mature, the magaspore had developed only to the stage of a one- to two-nucleus embryo sac. As the eight-nucleus embryo sac developed, some mamelon cells began to undergo programmed cell death, forming holes Into which the eight-nucleus embryo sacs extended, becoming "N" or "S" shaped. The development from a two-nucleus embryo sac to a matured eight-nucleus embryo sac lasted up to 10 d. Fruit-set from open pollination was less than 2%. The endosperm develops prior to division of the zygotic embryo and one to three embryos and endosperms were formed In the same fruit. A mature seed usually germinates to produce one seedling; however, two and three seedlings from one seed were also observed, albeit at a low frequency. Pollination trials showed that no seed sets when Inflorescences were covered with s bag; however, artificial pollination could Improve fruit set. Our pollinaUon trials and embryological studies proved that the flower of S. album Is dlchogamous and fruit set has high heterozygosity. 相似文献
140.
Mark A. Genung Jean-Philippe Lessard Claire B. Brown Windy A. Bunn Melissa A. Cregger Wm. Nicholas Reynolds Emmi Felker-Quinn Mary L. Stevenson Amanda S. Hartley Gregory M. Crutsinger Jennifer A. Schweitzer Joseph K. Bailey 《PloS one》2010,5(1)