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211.
We investigated the effects of selective logging on stand structure and regeneration in selectively logged subboreal forests
in Taisetsuzan National Park in Hokkaido in northern Japan. The basal area decreased and the size structure of trees altered
in the stands studied due to repeated, intense selective logging, in which larger trees were cut down as a priority. Sapling
density in the stands was much lower than that in primary forests. In the simple and multiple regression analyses that were
used to estimate the effects of selective logging on sapling density, sapling density had a significant positive correlation
with tree density and had little correlation with the density of logged stumps or the height ofSasa (dwarf bamboo) growing on the forest floor. These results suggest that the establishment sites around canopy trees influenced
the establishment of saplings, rather than the gaps caused by selective logging. However, both the coefficient of determination
and the standardized partial regression coefficient of multiple regression analysis were higher for the stand with a dense
cover ofSasa than for the stand with a sparse cover ofSasa. Thus, the success of regenerating forests with selective logging depends on both the site of advanced regeneration and the
light conditions that regulate growth. 相似文献
212.
Hiroaki Matsuo Nobuyuki Matsuka Koji Omori Yoshitsugu Koizumi Ichiro Takeuchi 《Fisheries Science》2010,76(1):147-153
In order to estimate the nitrogen loading from fish aquaculture facilities, we studied the nitrogen and carbon stable isotope ratios (δ15N and δ13C, respectively) in the brown macroalga Sargassum piluliferum and small amphipod crustaceans Caprella spp., both of which are lower trophic level biota found at fish and pearl oyster aquaculture facilities situated along the eastern coast of the Uwa Sea, Japan. This coastal region is one of the least populated areas along the Japanese coast. The mean concentrations of chlorophyll a, dissolved inorganic nitrogen, dissolved inorganic phosphate, and dissolved silicate-Si were 1.5- to 2-fold higher in samples from the fish aquaculture facilities than in those from the pearl oyster aquaculture facilities, indicating that the fish aquaculture facilities were associated with nitrogen loading. The δ15N abundance level in S. piluliferum collected from the fish aquaculture facilities was significantly higher (1.3‰) than that in macroalga collected at the pearl oyster aquaculture facilities, whereas that in Caprella spp., primary consumers, was only slightly higher (0.3‰). The feeding style of Caprella spp., which depends on suspended particulate organic matter and attached microalgae, is considered to the primary causal factor for the lack of a significant difference in δ15N abundance level between the two types of aquaculture facilities. Based on these results, we conclude that S. piluliferum found in close proximity of aquaculture facilities is a suitable organism for monitoring nitrogen loading from fish aquaculture facilities, through the analysis of δ15N. 相似文献
213.
Mikimasa Joh Taihei Matsuda Nobukazu Satoh Nobuyuki Tanaka Yoshiyuki Ueda 《Fisheries Science》2011,77(5):773-783
Brown sole Pseudopleuronectes herzensteini larvae and juveniles were reared to validate daily otolith ring formation. At 15°C, a check (a distinct ring) formed on the
sagittae and lapilli at 6 days after hatching, and clear increments regularly formed outside the check. For both otoliths,
the relationship between the number of days after hatching and number of increments was linear, and the slope of the line
was approximately 1; therefore, daily formation was validated. At 12°C, the check formed on the lapillus 8 days after hatching.
Accessory primordia (AP) began forming on the sagittae of metamorphosing larvae, and the shape of the sagittae became complicated.
AP were not formed on the lapillus; concentric rings were formed throughout larval and juvenile stages. Wide and obscure increments
formed on the lapilli during metamorphosis (metamorphosing zone, MZ). Based on MZ, concentric rings that have formed on the
lapilli of juveniles can be separated into larval and juvenile rings. The morphs of large juveniles’ lapilli were bilaterally
asymmetric, and the blind-side lapilli were most suitable for otolith microstructure analysis. This study provides fundamental
information for otolith microstructure analysis in wild brown sole. 相似文献