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71.
72.
Fanomezantsoa Randriarilala Toshihide Kitakado Daisuke Shiode Masayuki Sakaguchi Toshifumi Hayashi Tadashi Tokai 《Fisheries Science》2014,80(2):261-271
Information on the distribution and bloom scale of the giant jellyfish Nemopilema nomurai is necessary to understand the impact on fisheries. In October 2009, we had an opportunity for visual counting of N. nomurai around Japan from a research/training vessel. To take into account possibly severe missed detection of N. nomurai in the close vicinity of the vessel, detection functions were modified by introducing an additional parameter δ expressing the proportion of detectable N. nomurai within a threshold perpendicular distance. Some covariate effects in the detection process were also investigated. The δ-modified hazard-rate detection function with δ variation parameter of jellyfish body size was chosen as the best-fit one by AIC model selection. The results suggested that a higher proportion (>30 % or more) of N. nomurai were undetected in the vicinity of vessel. The δ-modified model had an advantage of no loss of left-truncated data and provided better estimation of density with the smaller coefficient of variation than the conventional left truncation approach. It is applicable to other line transect surveys, e.g. aerial surveys. High densities of N. nomurai were found in the central part of the Sea of Japan and off Iwate Prefecture. 相似文献
73.
Understanding organic matter characteristics(e.g., amount and state) of sediments is necessary for evaluating both the sediment and water environments; however, methods that have been proposed to investigate these characteristics are relatively expensive. This study attempted to evaluate the organic matter characteristics of littoral sediments by employing solely the loss on ignition(LOI)method, which is the most economical and accessible method in developing countries. Different types of sediments were first oven dried at 100℃ and then continuously burned at 200, 300, 400, 500, and 600℃ for 4 h at each temperature. The mass LOI at each temperature was calculated and compared with the 100℃ oven-dried weight. Our results suggested that the mass LOI across the temperature range of 200–300℃(LOI_(200-300)):mass LOI at 600℃(LOI_(600)) ratio(LOI_(200-300)/LOI_(600)) could represent different types of sediments as well as the organic matter:organic C ratio. Compared with the sediments unaffected by wastewater, the sediments that were more influenced by the inflow of domestic wastewater had a higher LOI_(200-300)/LOI_(600). Interestingly, LOI_(200-300)/LOI_(600) could also represent changes in the organic matter characteristics as a function of organic matter decomposition in sediments. In conclusion, the organic matter characteristics of littoral sediments could be evaluated using solely the LOI method, particularly with LOI_(200-300)/LOI_(600). 相似文献
74.
Growth variability of Pacific saury Cololabis saira larvae under contrasting environments across the Kuroshio axis: survival potential of minority versus majority 下载免费PDF全文
Akinori Takasuka Kirara Nishikawa Hiroshi Kuroda Takeshi Okunishi Yugo Shimizu Hideo Sakaji Shin‐Ichi Ito Tadashi Tokai Yoshioki Oozeki 《Fisheries Oceanography》2016,25(4):390-406
Growth variability was examined for Pacific saury Cololabis saira larvae under contrasting environments across the Kuroshio axis, based on samples collected during the winter spawning season in 2013 and 2014. The growth rate index (residual of the otolith marginal 3‐day mean increment width from the linear regression on knob length) of larvae was compared among three areas: the inshore side of the Kuroshio axis, the Kuroshio axis, and the offshore side of the Kuroshio axis in relation to sea surface temperature (SST), salinity (SSS) and chlorophyll‐a (CHL) concentration. The larvae were more densely distributed in the Kuroshio axis and offshore areas of higher temperature and salinity and lower chlorophyll‐a concentration than in the inshore areas of lower temperature and salinity and higher chlorophyll‐a concentration. No marked differences in the growth rate index were found among the three areas, even though the larvae in the inshore areas showed slightly higher growth rates in 2013. Despite the broad ranges of environmental factors, no clear relationship between the growth rate index and any environmental factor was detected. The survival potential of Pacific saury larvae was considered to be at least comparable under contrasting environments across the Kuroshio axis. Such a geographical homogeneity is concluded to be attributable to compensable effects of physical and biological factors. We hypothesize that the minority under physically‐unfavorable but biologically‐favorable conditions on the inshore side of the Kuroshio axis could survive equally well as the majority under physically‐favorable but biologically‐unfavorable conditions around the Kuroshio axis and on the offshore side of the Kuroshio axis. 相似文献
75.
Ikawa K Aoki M Ichikawa M Itagaki T 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2011,73(10):1359-1361
In the present study, we tried to detect DNA for ribosomal RNA genes of piroplasma parasites from the liver or blood of 43 Japanese serows (Capricornis crispus) in Iwate Prefecture of Japan by polymerase chain reaction. Approximately 500-bp amplicons were obtained in 35 (81.4%) of the 43 samples by amplification for V4 hyper-variable regions of the 18S rRNA gene, and the amplicons were considered to be DNA of Theileria species. The complete nucleotide sequences (1,700 or 1709 bp) of the 18S rRNA gene were determined in 20 samples and were divided into 5 genotypes that were phylogenetically separated into two different lineages showing a polyphyletic relation. The Theileria DNAs of the two different lineages were considered to be those of distinct species. 相似文献
76.
We examined arsenic (As) accumulation and speciation in the major cultivars currently grown in Japan, because differences in grain As levels among cultivars may influence dietary As exposure in Japanese people. Ten major cultivars (Oryza sativa L.) were grown under flooded conditions in a paddy field with a background level of As (low-As soil) or in pots filled with soil containing a high level of As (high-As soil). In the low-As soil, the total grain As ranged from 0.11 to 0.17?mg?kg?1, with a mean concentration of 0.14?mg?kg?1, and inorganic As was the major species in all cultivars. There were few genotypic differences in the levels of either total As or inorganic As in the grain. In the high-As soil, total grain As increased to a mean level of 2.4?mg?kg?1 in the 10 cultivars, with markedly increased levels of dimethylarsinic acid. The genotypic variations among cultivars in the levels of both total As and dimethylarsinic acid were statistically significant. However, the genotypic variability of inorganic As levels was quite small, and these levels remained low (at about 0.2?mg?kg?1) even when total As levels increased markedly. These results suggest that differences in grain As levels among Japanese cultivars may not influence dietary As exposure, because there is little genotypic difference in the accumulation of inorganic As, which is considered more toxic than organic As to humans. We discuss the possible mechanism of As accumulation in Japanese paddy rice, in the context of the accumulation of As species in the developing grain and in other plant tissues. 相似文献
77.
In the preceding paper (1), it was reported that even under aerobic shaking conditions, if R. capsulatus were mixed with Bacillus megaterium, the bacterial growth of both and nitrogen fixation were accelerated remarkably. 相似文献
78.
1. It was proved that under aerobic shaking conditions of the system of R. capsulatus mixed with Az. agilis or R. capsulatus mixed with B. megaterium, the bacterial growth of both and the nitrogen fixation were promoted markedly, comp:ired with the non-shaking culture. However, in the system of R. capsulatus mixed with B. subtilis under aerobic shaking conditions. such remarkable stimulative effects were not recognized altough some slow effects were recognized in the nonshaking culture. 2. It was also proved that under aerobic shaking conditions of the system of R. capsulatus mixed with Az. agilis or R. capsulatus mixed with B. megaterium the assimilative activity of carbon dioxide increased over 10 times more than in the separate pure culture. From these results, it is conceivable that a very good environment was created for the internal metabolism of R. capsulatus in such mixing systems (R-Az and R-Bm). 相似文献
79.
Tadashi Katayama Michiharu Kobayashi Azuma Okuda 《Soil Science and Plant Nutrition》2013,59(4):101-106
In previous papers (1,2), it was reported that in cultures of R. capsulatus mixed with other heterotrophic bacteria nitrogen fixation is accelerated and there is some production of slime substances (3), exchange of pyruvic acid (4–6), amino acids, carbohydrates (7) and others in these mixed systems. There is also symbiotic association between R. capsulatus and other heterotrophic bacteria (Azotobacter) in nature (8). 相似文献
80.
The effect of presowing wheat seed treatments was investigated for the salt-sensitive variety Blue Silver and relatively salt-tolerant variety PARI-73 at the germination and early seedling stages. Seeds were treated with distilled water (DW) or 10/50 mm KCl, KNO3 , CaCl2, Ca(NO3)2 and then germinated in DW or 200 mm NaCl. Treatment with calcium (Ca) or potassium (K) did not lead to a significantly higher rate for final germination than the DW treatment. Ca salt treatments significantly improved shoot growth during the early seedling establishment stage in both varieties, especially in the salt-sensitive variety Blue Silver. There were significant differences in the Ca content of seeds after various presowing treatments. There were also significant differences between both varieties in the ion contents after seed treatment. However, these differences appeared to be related to the improvement of shoot growth during the early seedling establishment stage and not to the effectiveness of pres owing seed treatments in increasing germination. 相似文献