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21.
With data sampled from 2003 to 2006, this study presents the effects of temperature, food availability (C), and body size on the somatic growth rate [^(g)] \hat{g} (mm day−1) and on the size-specific growth rates [^(G)] \hat{G} (day−1) of larval Japanese anchovy Engraulis japonicus caught in Hiuchi-nada, Seto Inland Sea, Japan, a semi-enclosed narrow sea. C was calculated using an individual-based model, which is an encounter model between copepods and anchovy where the anchovy
resulted in a successful capture of the copepod. [^(g)] \hat{g} decreased with increasing anchovy length, but increased with increasing C. No significant relationship was found between [^(g)] \hat{g} and temperature. [^(G)] \hat{G} decreased with increasing temperature, but anchovy weight, on the other hand, increased with increasing C. In the literature, the mechanism of growth determination for larvae of pelagic fish species is considered to be primarily
determined by sea temperature and secondarily by food availability. However, [^(g)] \hat{g} and [^(G)] \hat{G} were found to be dependent on C rather than temperature. [^(G)] \hat{G} was dependent on anchovy weight rather than C and temperature. For forecasting the number of days required for development from an arbitrary pre-recruitment size to the
recruitment size, we address not only temperature but also food availability and the size effect when considering the mechanism
of growth determination for larvae. 相似文献
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Seyed Mohamad Mahdavi Mohammad Reza Neyshabouri Haruyuki Fujimaki 《Eurasian Soil Science》2016,49(8):915-925
Simulation of heat transfer in soil under steady and unsteady situations requires reliable estimate of soil thermal conductivity (λ) at varying environmental conditions. In the current work several soil thermal conductivity predicting models including I) de Vries, II) Campbell, III) combined de Vries and Campbell and IV) de Vries-Nobre were evaluated for the four soils of coarse sand, sandy loam, loam and clay loam textured at varying in temperature and bulk density at low moisture range. Thermal conductivities measured by the cylindrical probe method served as the reference for models assessment. Results showed that approximately same thermal conductivities obtained by the five methods at low moisture range (θ ≤ 0.05 m3/m3). Also the de Vries and de Vries-Campbell models produced accurate than Campbell and de vries-Nobre models. The accuracy of the two models increased with soil compaction but decreased with temperature rise. Campbell model showed more reliability at higher (311.16 and 321.16 K) temperatures; but its accuracy declined with soil compaction in current work. It seems that assuming needle shape for the soil particles is far away from the reality whereas assuming spherical shapes may be more realistic and produced more satisfactory prediction of thermal conductivity. The compaction would alter particle arrangement and may increase the contact area of particles; and then make them behave more or less spherical shape.it seems thermal conductivity in solid particles increase via increasing in temperature. Since a modified mineral shape factor, gm, was developed as a combination between sphere and needle according to geometric mean particle diameter as well as bulk density and temperature as modifying factors. This factor increased the accuracy of de Vries-Nobre model up to 10.37%. Regarding nonlinear regression model, moisture content, bulk density, temperature and quartz content demonstrated significant effect on soil thermal conductivity in our investigation. 相似文献
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26.
Reiji Masuda David A. Ziemann Anthony C. Ostrowski 《Journal of the World Aquaculture Society》2001,32(3):309-316
Abstract.— Nutritional condition in larval fish culture has generally been evaluated based on growth and survival, and stress tolerance by air exposure. Here we made direct observations of fish in rearing tanks to estimate the quality of the fish. Pacific threadfin Polydactylu.s sexfilis larvae were reared with rotifers and Artemia nauplii enriched with three levels of highly unsaturated fatty acids (HUFA). The three levels were defined as no-, medium-, or high-HUFA groups, in which the fatty acids emulsions contained 0, 30, or 50%. respectively. of docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA). The formation of patchiness (dense aggregations of fish on the surface) and development of schooling behavior were observed in four replicate rearing tanks for each feed treatment. Patchiness was formed in every tank with the highest densities of 60–250 fish/L on day 7–8 posthatch. Both medium-HUFA and high-HUFA groups showed schooling behavior at 19 d after hatching, whereas fish in the no-HUFA group did not form schools even at day 25. The body lengths of fish from each group were not significantly different, although the no-HUFA group suffered high mortality after day 20. Our results suggest that HUFA deficiency has a serious negative impact on P. sexfilis during metamorphosis rather than during the early larval stage. We also consider that direct observation rather than stress tests by air exposure may be an effective tool to measure the quality of juvenile fish. 相似文献
27.
Reiji Fujimaki Akiyuki Kawasaki Yoshikazu Fujii Nobuhiro Kaneko 《Journal of Forest Research》2008,13(6):380-385
The water chemistry of 51 headwater streams was studied in the Tanzawa Mountains, western fringe of Southern Kanto Plain,
Japan. The relationships to soil N processes and catchment topography were also evaluated using a geographic information system
with fine-scale map data. The average concentration of total dissolved N was 0.74 mg-N L−1, of which 95% consisted of NO3
−-N. Stream N concentrations were not different among bedrock geologies and among vegetations of the catchments. Stream NO3
−-N marginally correlated to soil nitrification. Stream NO3
−-N also tended to be high in areas with steep and south-facing slopes. These results imply that N transport from Tanzawa forest
ecosystems is related to hydrological and biological processes associated with catchment topography.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
28.
Eurasian Soil Science - Soil salinity is an increasing threat to agriculture and is a major factor in reducing plant productivity in arid and semi-arid regions. Knowledge of the transport process... 相似文献
29.
Ryunosuke Tateno Keitaro Fukushima Reiji Fujimaki Tetsuya Shimamura Masami Ohgi Hirotsugu Arai Nobuhito Ohte Naoko Tokuchi Takahito Yoshioka 《Journal of Forest Research》2009,14(5):276-285
We investigated soil net nitrogen mineralization rate, above- and belowground biomass allocation, and nitrogen use in a Cryptomeria japonica plantation chronosequence. Total biomass accumulation showed an asymptotic accretion pattern, and the peak total biomass
accumulation rate occurred approximately 30 years after afforestation. Soil net nitrogen mineralization rate was lowest 30 years
after afforestation. Between years 30 and 88, net nitrogen mineralization increased again. These results indicate that an
imbalance in soil nitrogen supply and plant nitrogen demand occurred approximately 30 years after afforestation. Furthermore,
leaf nitrogen concentration, which was used as an index of plant nitrogen status, was lower in mature forest than in young
forest, suggesting that mature stands did not take up nitrogen as successfully. If soil resources such as nitrogen limit plant
growth, plants may increase biomass allocation to fine root structure; however, fine root biomass was not higher in 30- and
88-year-old stands than in younger stands, suggesting that changes in biomass allocation may not be effective against nitrogen
deficiency in a C. japonica plantation chronosequence. 相似文献
30.
In finfish aquaculture, fish meal is heated during the manufacturing process, which affects the digestibility and protein absorption by fish. However, manufactured fishmeal that is not heated does not undergo thermal denaturation. Few studies have investigated the effects of non-heated animal protein sources on the growth performance of fish. We investigated the effects of heated and non-heated squid and krill meal as diets for red sea bream. Five test diets were formulated to contain heated squid meal, non-heated squid meal, heated krill meal, non-heated krill meal, and fish meal as a control. Fifty fish (initial mean weight?=?3.5 g) were distributed in ten 100-l experimental tanks. Fish were fed one of the five diets 3 times daily until satiation for 5 weeks. Regarding growth performance, fish fed the krill meal diet exhibited better growth than those fed squid meal during the first week of the rearing period. However, the squid meal diet group showed better performance than the krill meal diet group during the third week. Moreover, differences in body weight among treatments were greater during the fifth week. Better weight gain and thermal growth coefficient were recorded in the non-heated diet groups than in the heated diet groups. Higher feed intake was observed in the non-heated diet groups than in the heated diet groups. These results suggest higher performance of non-heated squid and krill meal as the protein source of the red sea bream diet. Further, the suitability of the diet type (e.g., squid and krill) might depend on the feeding period and/or developmental stage of fish. 相似文献