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361.
Identification and characterization of proteases from skin mucus of tambacu,a Neotropical hybrid fish 总被引:1,自引:0,他引:1
C. M. C. Salles P. Gagliano S. A. T. Leitão J. B. Salles H. L. M. Guedes V. P. F. Cassano S. Giovanni De-Simone 《Fish physiology and biochemistry》2007,33(2):173-179
Skin secretions of fishes constitute a rich source of proteins with a broad spectrum of antimicrobial properties. We report
here the characterization of proteases from skin mucus of tambacu, an economically important Neotropical hybrid fish. The
effects of pH on the proteolytic activities of the mucus acting on various substracts – hemoglobin, casein, bovine serum albumin
(BSA) and ovalbumin (OVA) – were tested. Optimal pH values for protease activity on hemoglobin were 4.5 and 8.5, on casein,
8.5, on BSA, 5.0 and 7.5, and on ovalbumin, 4.5 and 6.5. The proteolytic activity was inhibited on all of these substrates
in the presence of specific inhibitors: caseinolytic activity was inhibited by inhibitors of serine and metalloproteases;
hemoglobinolytic activity was inhibited by serine, aspartic and metalloproteases inhibitors; albuminolytic activity on BSA
was inhibited by serine and aspartic proteases inhibitors, and on ovalbumin, by cysteine and aspartic proteases inhibitors.
Gelatin zymography revealed that the skin mucus of tambacu consisted primarily of serine and metalloproteases. Hemoglobin
zymography showed one proteolytic band inhibited by EDTA, whereas casein zymography showed two proteases inhibited by serine
proteases inhibitors. We were able to identify all classes of proteases in the mucus from the skin of tambacu. These, and
these results suggest that the proteolytic activities of the skin mucus of fish may play an important role in the defense
against microorganisms and ectoparasites. 相似文献
362.
Tatyana Zak Raviv Deshev Ayana Benet‐Perlberg Alon Naor Igal Magen Yechiam Shapira Raul W Ponzoni Gideon Hulata 《Aquaculture Research》2014,45(3):546-557
Genetic parameters and selection responses were obtained for harvest body weight of blue tilapia (Oreochromis aureus) from data collected over three generations in a selected population. A total of 18 194 records representing 186 sires and 201 dams were used in the analysis. Within generation heritability estimates for harvest body weight ranged from 0.18 to 0.58. When data from more than one generation were included in the analysis, heritability estimates became more stable (0.33–0.40) and it was 0.33 when all data were included in the analysis. The common full‐sib effect accounted for 10% of the phenotypic variance in the full data set. Heritability for survival from stocking to harvest was estimated at 0.01 and 0.09 in actual units (fitting an animal model) and in the logit (sire model) scale respectively. The genetic correlation between harvest body weight and survival was 0.22 and not significantly different from zero. The total selection response for harvest body weight over the three generations of selection measured as the difference between least‐squares means of selected and control lines was 17.7%. The corresponding figure when response was measured as the difference between mean breeding values of selected and control lines was 19.6%. The average inbreeding coefficient was 0.003 after three generations of selection. These results indicate that there are good prospects for the genetic improvement of harvest body weight in blue tilapia. 相似文献
363.
Francisco Gerson Araújo Mrcia Cristina Costa de Azevedo Gustavo Henrique Soares Guedes Wagner Uehara 《Ecology of Freshwater Fish》2022,31(1):45-59
Increases in temperatures over the last century, more intensively after the eighties, were recorded in several databases for the south-eastern Brazil. These increases are likely to change fish communities in aquatic systems by decreasing abundances, biomass and sizes of some species more sensitive to climate change. Reservoirs may be particularly susceptible to the effects of climate change, as they isolate previously connected areas limiting fish dispersal and migration, as well as increasing water temperature and thermal stratification. We assessed temporal changes in the abundance and biomass of the ichthyofauna in an isolate reservoir (inflowing waters from small tributaries in a highland region) aiming to associate changes with climate effects over three decades (1990, 2000, 2010). Two abundant native species, a loricariid Loricariichthys castaneus (Castelnau, 1855) and a cichlid Geophagus brasiliensis (Quoy & Gaimard, 1824), were selected to assess eventual response to climate changes in their geographical distribution in the Southeast Atlantic Hydrographic Region, considering different carbon emission scenarios using ecological niche models. A decrease in the densities and biomass of the ichthyofauna and of the two selected species were observed in both summer and winter over the three decades, coinciding with increases in temperatures. These decreases were correlated with increases in positive anomalies of temperature, which may be an indicator of climatic changes, although with low explanation of the data variation. The mean size of L. castaneus decreased between the nineties and 2010, whereas no significant trend was found for the size of G. brasiliensis. Our predictions of new area for future adequacy indicated a loss in the distribution area for both species (mainly for G. brasiliensis), considering the most pessimistic scenario for 2050 and 2070, possibly due to climatic changes. Both hydroelectric dams and global warming pose threats to freshwater fish diversity, and both will interact. Changes observed in the fish assemblage over the last decades were essential for an assessment of the consequences of global warming in this type of reservoir combining larger scale studies with future projections. 相似文献