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811.
In Ireland much of the land available for plantation establishment requires some degree of soil cultivation and drainage to
improve its suitability for tree growth. The method of cultivation and drainage normally varies depending upon the soil type
and its drainage characteristics. Little research has been carried out on the impact of practices such as mounding and mole
drainage upon rooting and biomass production in young crops. The research reported in this paper was carried out on four sites
where the general soil type was surface water gley. Three of the sites studied were afforestations on old farmland, while
the fourth site was a reforestation of a windblown stand. The cultivation methods investigated included mounding, mole drainage
with mounds, mole drainage only and ripping. Sitka spruce trees ranging in age from five to thirty years were excavated from
these experimental sites to describe the impact of different soil cultivation techniques upon root architecture and above
and below ground biomass production. The results showed that while the effect of mound drainage upon water table level varied
from site to site, the establishment of trees on mounds led to an increase in above and below ground biomass production. Mole
drainage of these sites without mounds, did not lead to any increase in root or shoot development when compared with trees
growing on uncultivated/undrained ground.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
812.
Concentrations of pigments in needles of yellowish Norway spruce [Picea abies (L.) Karst] trees suffering from either N, Mg or K deficiency in field sites in southeast Norway are reported. The yellowish
trees had a considerably lower (roughly 50%) pigment concentration, as well as a lower chlorophyll/carotenoid ratio, compared
to green trees within the same sites. Yellowing was interpreted as a general bleaching of colour, as well as a slight turn
from the green (chlorophylls) towards yellow (lutein). Concentrations of pigments were highly intercorrelated. N deficiency
was especially associated with low α-carotene concentrations. This was interpreted as α-carotene being the most sensitive
pigment to stress. However, this pigment might be specifically sensitive to N deficiency. Carbohydrate concentrations were
slightly higher in yellowish trees.
Received: 5 June 1997 / Accepted: 29 August 1997 相似文献
813.
814.
Izabela Sondej Timo Domisch Leena Finér Wojciech Czechowski 《Agricultural and Forest Entomology》2021,23(3):287-296
- Wood ants, species of the subgenus Formica s. str., are one of the most important groups of insects in forest ecosystems due to their high abundance and activity.
- We assessed the foraging pressure of Formica polyctena and Formica rufa, two dominant wood ant species in the Białowieża Forest. In addition, we compared coniferous and mixed stands in these respects.
- In mixed stands F. polyctena visited more trees per plot than F. rufa. F. polyctena might forage a larger area due to higher population sizes, which further confirms higher foraging pressure of F. polyctena in comparison with F. rufa.
- In our study area, host trees of the ant–aphid mutualism were larger in diameter than nonhost trees. The ants also preferred trees situated closer to their nests. In both mixed and coniferous stands, the most visited tree species was Norway spruce. Thus, we can conclude that Norway spruce seems to be preferred by the ant. The decline of living spruce in the Białowieża Forest may endanger their food source and impact the vitality of ant colonies.
815.
T. Nikkanen T. Aronen H. Häggman M. Venäläinen 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2000,101(4):511-518
An in vitro germination method was used to study variation in pollen viability, that is pollen-tube growth rate together with
germination percentage, among the Picea abies genotypes in a seed orchard. The method permits easy, rapid screening of large numbers of genotypes. Significant variation
in pollen viability among the genotypes was evident, the differences among the pollen-lot means being 7–10–fold in different
years. No correlation was found between the average pollen viability and the phenology, growth or growing-site characteristics
of the pollen donors. However, there appeared to be pollen lots that either benefit from a higher germination temperature
or else germinate faster at lower temperatures. The significant variation in pollen viability among the pollen donors indicates
a potential for male gametophyte competition. This, together with the observed genotype-environment interactions in pollen
performance, may contribute to the variable genetic composition of seed produced in the seed orchard.
Received: 9 December 1999 / Accepted: 22 December 1999 相似文献
816.
817.
818.
White spruce [ Picea glauca (Moench) Voss.] seedlings were grown in solution culture and treated with 20 mg I-1 triadimefon [1-(chlorophenoxy)-3,3-dimethyl-1-(1,2,4-triazol-1-yl)-2-butanol] for 4 weeks and then subjected to osmotic stress with polyethylene glycol 3350. Water potentials and electrolyte leakage were measured in control and triadimefon-treated seedlings before and after the plants were subjected to osmotic stress. The plasma membranes were isolated from needles to study their lipid composition and the activity of plasma-membrane bound ATPase. Triadimefon treatment reduced water potentials and increased leakage of electrolytes from seedlings. However, when the seedlings were exposed to osmotic stress, triadimefon-treated plants maintained higher water potentials and leaked less electrolytes compared with the control plants. Both triadimefon and osmotic stress treatments inhibited the activity of plasma membrane-bound ATPase and altered the composition of free sterols in the plasma membranes. Triadimefon-treated plants contained traces of campesterol, which was not present in control. Osmotic stress drastically reduced phospholipid:protein and sterol:protein ratios and increased sterol:phospholipid ratios in the plasma membranes 相似文献
819.
Predicted changes in the synchrony of larval emergence and budburst under climatic warming 总被引:1,自引:0,他引:1
Summary The impact of climatic warming on the synchrony of insect and plant phenologies was modelled in the case of winter moth (Operophtera brumata) and Sitka spruce (Picea sitchensis) in the Scottish uplands. The emergence of winter moth larvae was predicted with a thermal time requirement model and the budburst of Sitka spruce was predicted from a previously published model (Cannell and Smith 1983) based on winter chilling and thermal time. The date of emergence of winter moth larvae was predicted to occur earlier under climatic warming but the date of budburst of Sitka spruce was not greatly changed, resulting in decreased synchrony between larval emergence and budburst. The general question of how a change of climate might affect phenological synchrony and insect abundance is discussed. 相似文献
820.
The use of ion exchange resin bags to assess N availability beneath pure spruce and larch + spruce stands growing on a deep peat soil 总被引:1,自引:0,他引:1
Summary Mineral N accumulation by ion exchange resins placed beneath the forest floor layer of pure spruce and mixed larch + spruce
stands indicated greater N availability in the presence of larch. Findings were in qualitative agreement with those of previous
incubation experiments. 相似文献