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71.
The importance of dietary 20:5n‐3 (EPA), 22:6n‐3 (DHA) and 20:4n‐6 (ARA) for growth, survival and fatty acid composition of juvenile cockles (Cerastoderma edule) was investigated. Cockles of 6.24 ± 0.04 mm and 66.14 ± 0.34 mg (live weight) were distributed into three treatments where live microalgae diets were fed constantly below the pseudofaeces production threshold, for three weeks. Diets had distinct fatty acid profiles: high EPA (53% Chaetoceros muelleri + 47% Pyramimonas parkeae), no DHA (47% Brachiomonas submarina + 53% Tetraselmis suecica) and low ARA concentrations (73% P. parkeae + 27% Phaeodactylum tricornutum). Growth was positively affected by high EPA and low ARA diets, whereas no significant growth was observed for the no DHA diet. High mortality of cockles fed no DHA diet raises questions about its suitability for cockles. In balanced diets with EPA and DHA, lower concentrations of ARA do not limit growth. The impact of dietary fatty acids was evident in the fatty acids of neutral and polar lipids of cockles. In polar lipids of all cockles, there was a decrease in EPA, in contrast to an increase in DHA. The combination of EPA and DHA in a live microalgae diet was beneficial for the growth and survival of juvenile cockles.  相似文献   
72.
In this study, we evaluated the production potential of the polyculture of Freshwater Angelfish (Pterophyllum scalare, Cichlidae) and Pacific white shrimp (Litopenaeus vannamei). Two experimental trials were set up. The first trial entailed the use of a randomized design to investigate three treatments options: angelfish monoculture, shrimp monoculture, and fish and shrimp polyculture in 12 experimental 15 m2 ponds. In the second trial, we investigated two treatments (polyculture of caged fish and uncaged fish) in 10 experimental units. In trial 1, polyculture negatively affected fish growth and survival. However, fish did not affect shrimp growth and the greatest profit was achieved in polyculture. In trial 2, caging fish improve the growth of both fish and shrimp. An economic analysis showed the greatest profit and benefit cost ratio for caged fish compared with uncaged fish. We conclude that growing P. scalare and L. vannamei together is a better strategy than shrimp monoculture in low‐salinity water. The use of caged fish in such a polyculture operation would enhance productivity and profitability.  相似文献   
73.
This study aimed to verify the preference and infestation level of Anastrepha fraterculus (Diptera: Tephritidae) [South American fruit fly] in fruits of guava cultivars and to correlate them to variables such as peel coloration, soluble solids and pH of fruit cultivars. The following cultivars were used: Pedro Sato, Paluma, Cascão and Século XXI. The infestation was evaluated in cages, considering two scenarios: no-choice and multiple choice. In both tests, evaluations of the fruit attraction to insects were conducted for a period of 1′, 3′, 5′, 10′, 20′, 30′, 1 h, 2 h, 6 h, 12 h and 24 h. The visit of A. fraterculus on the assayed cultivars in relation to the time was studied by logistic regression. After 10 days, the number of larvae in each fruit was recorded. In the multiple choice test, the visit proportions were significantly higher in the fruits of cvs. Século XXI and Pedro Sato than in those of cvs. Paluma and Cascão. In the no-choice test, the visit proportions were significantly lower in the Paluma fruits. In both tests, the rate of fruit infestation by A. fraterculus did not differ among cvs. Pedro Sato, Paluma and Cascão, whereas the fruits of cv. Século XXI were more infested. The indexes of pH did not interfere with the infestation of A. fraterculus, whereas a high rate of soluble solids and low color angle appear to be crucial for discriminating the fruits of the most susceptible cultivars. Infestation rate of Século XXI fruits displayed significant correlations with: °Brix (r= 0.7078) and color angle (h) (r= –0.9499) of guava fruits under the multiple choice conditions.  相似文献   
74.
The objective of this paper was to evaluate the effect of three different sources of fiber (tifton hay, soybean hulls, and whole cottonseed) in spineless cactus diets for sheep in the semiarid region of northeastern Brazil. Twenty-one sheep in finishing phase with indeterminate breed, non-castrated, and with initial weight of 18.90?±?1.07 kg were randomly distributed to individual stalls where they were confined for the duration of the experiment. The intakes of dry and organic matter, total carbohydrates, and total digestive nutrients were not influenced (P?>?0.10) by the different fiber sources (1.10, 0.97, 0.73, and 0.80 kg/day, respectively). However, sheep which received the whole cottonseed diet were characterized by a lower (P?<?0.10) intake of crude protein and neutral detergent fiber and greater (P?<?0.10) intake of ether extract (0.11, 0.29, and 0.048 kg/day, respectively). The different sources of fiber resulted in similar times spent feeding (P?>?0.10), although the rumination time was greater for tifton hay (P?<?0.10) (429.05 min/day). The digestibility coefficient of dry and organic matter differed between the treatments (P?<?0.10), with the soybean hull diet showing a higher level of digestion (83.23 and 86.72 %, respectively). The whole cottonseed diet gave the smallest digestibility coefficient of crude protein (68.95 %) and greatest for ether extract (85.94 %). The daily weight gain of animals fed on whole cottonseed was significantly lower (P?<?0.10). On the basis of these findings, we recommend the use of tifton hay or soybean hulls as important additional source of fiber in forage spineless cactus diets for sheep in finishing phase.  相似文献   
75.
Sugarcane is one of the crops responsible for the high consumption of fertilizers in Brazil. To minimize this demand a sustainable alternative is to increase the studies to evaluate the beneficial effects of the relationship between plants/microorganisms, mainly plant growth-promoting bacteria. The objectives of this study were: a) to evaluate potentially diazotrophic bacteria isolates from sugarcane in adverse environmental conditions; b) inoculate these bacteria in sugarcane to evaluate their ability in plant growth-promotion. The study was carried in the Northeast of Brazil. Bacterial genera Burkholderia sp., Pantoea sp., Stenotrophomonas sp. and Enterobacter sp. were evaluated in different culture medium and later the bacterial isolates were inoculated in sugarcane evaluating the plant growth-promotion. Stenotrophomonas sp. and Pantoea sp. were tolerant to salinity and to different sources of carbon in acid medium and too tolerated high concentrations of pesticides and produced quorum sensing molecules (QS), but did not increase the dry matter production of sugarcane. Burkholderia sp. and Enterobacter sp. were more sensitive to salinity and pest control, but were more effective in plant growth-promotion. The tolerance of the bacteria to the adverse environmental conditions interfered negatively in the ability to plant growth-promotion.  相似文献   
76.
Excessive algae growth has generated conflicts on the use of water supplies; therefore, the focus on new technologies to remove algae from water bodies is demanding. The aim of the present study was to assess the effect of hydrodynamic cavitation on the inactivation of microalgae belonging to genus Scenedesmus. A laboratory-scale experimental apparatus was built in order to accomplish this goal; it consisted of a Venturi device designed to generate the cavitation phenomenon. Suspended microalgae samples were treated for 60 minutes under different cavitation intensities (cavitation number—Cv—ranging from 0.17 to 0.27). Results evidenced that microalgae decay over time can be modeled through first-order kinetics. The maximum removal efficiency (85%) was recorded at the highest cavitation intensity (Cv?=?0.17). The removal efficiency decreased as the cavitation number increased. Hydrodynamic cavitation was effective in inactivating Scenedesmus; it produced irreversible damages to cell morphology such as flotation spines removal, cell wall lesions, cytoplasm extravasation, and cavity formation. Assumingly, hydrodynamic cavitation has great potential to treat eutrophic water bodies. Furthermore, it represents a sustainable removal technique, since it does not produce secondary pollution.  相似文献   
77.
The definition of nitrogen doses for baru species becomes necessary because each forest species responds differently to nitrogen fertilization. The aim of this study was to evaluate baru seedlings' response to nitrogen, phosphorus, and potassium (NPK) fertilization and liming. The experiment was conducted in a greenhouse in a randomized blocks design, arranged in a 5 × 2 factorial scheme, being the factors consisted of five doses of nitrogen in covering (0, 75, 150, 225, and 300 mg dm?3) and substrate with and without limestone and PK, with four replications. At 60 days after transplanting, the plant height, stem diameter, number of leaflets, leaf area, shoot dry mass, chlorophyll content, N content in the leaves, root length, root volume, root dry mass, height/stem diameter ratio, shoot dry mass/root dry mass ratio, and Dickson quality index were evaluated. The substrate with liming influences positively the root dry mass. Nitrogen and PK fertilization promote increase in the relative chlorophyll content and N concentration in the leaves.  相似文献   
78.
In the wet tropics, near the Atlantic Coast of Brazil, drought may reduce plantation yields by as much one-third over a six-to-seven-year rotation. For land owners, annual variation in production cannot be estimated with empirical models. In this paper, we examine whether the process-based growth model, 3-PG is sufficiently sensitive to climatic variation to provide a virtual record of changes in growing stock across 180,000 ha eucalypt plantation estate. We first mapped variation in climate and soil properties, and then ran simulations for the current planted forest with ages varying from one to seven years. Model predictions of stand volume and mean tree diameter agreed closely with measurements acquired on 60 reference plots monitored over the test period; the prediction of mean annual increment (MAI) was less reliable. Available soil water (ASW) and leaf area index (LAI) were also measured and compared with the model estimations. Vapour pressure deficit (VPD) and ASW accounted for most of the variation in yields. We conclude that this spatial modelling approach offers a reasonable alternative to extensive ground surveys, particularly when climatic variation extends beyond the historical average for a region.  相似文献   
79.
80.
In the present review, the ongoing researches about selenium research in fish nutrition have been comprehensively discussed. Selenium research is getting popularity in fish nutrition as it is required for the normal growth and proper physiological and biochemical functions in fish. Its deficiency or surplus amounts create severe problems in fish. It is available as inorganic form, organic form, and nano form. In fish, most of the previous research is about the selenium requirements for fish by using only one selenium source mainly the inorganic one. Selenium shows maximum biological activity and bioavailability when it is supplied in proper form. However, to differentiate the more bioavailable and less toxic form of selenium, sufficient information is needed about the comparative bioavailability of different selenium forms in different fish species. In fish, important data about the new forms of selenoproteins is still scarce. Therefore, it is necessary to focus on the determination and elucidation of the new selenoproteins in fish through the utilization of recent approaches of molecular biology and proteomics. The adaptation of these new approaches will replace the old fashioned methodologies regarding the selenium research in fish nutrition. Moreover, the use of molecular biology and proteomics-based new approaches in combination with selenium research will help in optimizing the area of fish nutrition and will improve the feed intake, growth performance, and more importantly the flesh quality which has a promising importance in the consumer market.  相似文献   
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