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911.
Generalized additive models (GAMs) were fitted to sardine (Sardina pilchardus) egg distribution data from three daily egg production method surveys. The results showed that the area of egg cover off Portugal decreased significantly from 11 800 km2 in 1988 to 7000 km2 in 1997 and 7400 km2 in 1999. This is because of a significant reduction in sardine egg presence off northern Portugal, GAM estimated areas being similar or higher in the late 1990s for southwestern and southern Portugal. The distributional area covered by larvae was not estimated for 1988 (larval distribution extended beyond the survey area), although it was probably higher than the 9600 km2 for 1997 and 5500 km2 for 1999. In 1997 and 1999, the Gulf of Cadiz was also sampled, indicating extensive areas with sardine eggs and larvae (more than 50% of the total area of distribution off Portugal). Standardized data from 15 ichthyoplankton surveys between 1985 and 2000 show a decline in the mean probability of egg presence within the Portuguese continental shelf from the mid‐1980s to the late‐1990s, because of a marked reduction in egg presence off northern Portugal. Sardine larval data from the same surveys suggest that the reduction in mean probability of presence in the north is less marked than for eggs (although this comparison ignores the presence of sardine larvae beyond the continental shelf in the 1980s). Similar changes off northern Portugal and western Galicia are observed in commercial sardine catches and the acoustically estimated area of fish distribution. It is possible that the observed decline in spawning area off northwestern Iberia during the 1990s is indirectly reflecting the prevalence of environmental conditions detrimental to sardine recruitment (northerly winds during winter that favour coastal upwelling and offshore transport), which have reduced the spawning contribution of young fish in that area. 相似文献
912.
Theaim of this study was to examine the survival of fingerlings of silver catfish,Rhamdia quelen, in water with different pH and hardnessvalues. Fingerlings (1.60 ± 0.14 g; 5.67 ± 0.15cm) were randomly assigned to 35 treatments (in triplicate) andmaintained in 44 L polyethylene tanks (10 fingerlings/tank) for 96h. Fingerlings were exposed to seven solutions of varying pH (3.5,3.75, 4.0, 7.0, 9.5, 10.0, and 10.5) and five solutions of varying hardness(30,70, 150, 300, and 600 mg.l–1 CaCO3).Survival was assessed at 12, 24, 48, 72, and 96 h. Fingerlingmortality was 100% after 12 h exposure to pH 3.5 at all hardnesslevels, whereas mortality at pH 3.75, 10.0, and 10.5 decreased with increasinghardness. There was no mortality of fingerlings exposed to pH 4.0, 7.0, and 9.5at all hardness levels. The results allow us to conclude that the hardnesslevels studied do not affect the survival of silver catfish fingerlings exposedto pH 3.5, 4.0, 7.0, and 9.5 for 96 h. However, the increase ofwater hardness improved survival of fingerlings of this species exposed to pH3.75, 10.0, and 10.5. 相似文献
913.
Eliane Marinho-Soriano Marcos Rogério Camara Thiago de Melo Cabral & Marcella Araíyo do Amaral Carneiro 《Aquaculture Research》2007,38(2):182-187
The aim of this study was to evaluate the use of Gracilaria cervicornis meal as a partial substitute for the industrial feeds used in shrimp (Litopenaeus vannamei) farming. A total of 90 L. vannamei juveniles (0.34 g) were assigned randomly into nine experimental units at a stocking density of 10 shrimp tank−1 and fed a commercial shrimp feed (CSF; 35% crude protein) as a control treatment, a feed made entirely of G. cervicornis (GCM), and a mixture of equal parts of the commercial shrimp feed and the Gracilaria meal (MIX) for 30 days. Over the first 2 weeks of the experiment, the survival was high (100%) in all dietary treatments. However, at the termination of the feeding trial survival decreased to 40% in shrimp fed GCM, significantly lower (P<0.05) than survival of shrimp fed the commercial diet control (CSF) or MIX treatments (100%). The highest growth performance was obtained in the CSF or MIX treatment groups. The absolute growth increase in these groups was significantly higher than for shrimp fed GCM. Similarly, the specific growth rates (SGRs) of shrimp given feeds containing CSF (5.11% day−1) and MIX (4.71% day−1) were significantly greater (P<0.05) than that of shrimp fed GCM pellets (0.44% day−1). The feed efficiency ratios (FERs) were 64 for CSF, 54.3 for MIX and 3.3 for GCM. The results obtained in this study indicated the effectiveness of using G. cervicornis as a partial substitute for shrimp feeds. To our knowledge, this is the first time that the concept that macroalgae can partially substitute for the industrial feeds used in shrimp (L. vannamei) farming has been demonstrated. 相似文献
914.
S. Sundar Jani Heino Fabio de Oliveira Roque John P. Simaika Adriano S. Melo Jonathan D. Tonkin Davidson Gomes Nogueira Daniel Paiva Silva 《水产资源保护:海洋与淡水生态系统》2020,30(6):1238-1250
- Motivated by recent global initiatives for biodiversity conservation and restoration, this article reviews the gaps in our understanding of, and the challenges facing, freshwater macroinvertebrate biodiversity and conservation in tropical regions.
- This study revealed a lack of adequate taxonomic, phylogenetic, and ecological information for most macroinvertebrate groups, and consequently there are large‐scale knowledge gaps regarding the response of macroinvertebrate diversity to potential climate change and other human impacts in tropical regions.
- We propose ideas to reduce the impact of key drivers of declines in macroinvertebrate biodiversity, including habitat degradation and loss, hydrological alteration, overexploitation, invasive species, pollution, and the multiple impacts of climate change.
- The review also provides recommendations to enhance conservation planning in these systems (as well as providing clear management plans at local, regional, and national levels), integrated catchment management, the formulation of regulatory measures, the understanding of the determinants of macroinvertebrate diversity across multiple scales and taxonomic groups, and the collaboration between researchers and conservation professionals.
- It is suggested that the integrated use of macroinvertebrate biodiversity information in biomonitoring can improve ecosystem management. This goal can be facilitated in part by conservation psychology, marketing, and the use of the media and the Internet.
915.
916.
Gabriel Jesus Alves de Melo ;Viviani Gomes ;Camila Costa Baccili ;Luiz Alberto Luz de Almeida ;AntonioCezar de Castro Lima 《农业科学与技术》2014,(10):865-873
Somatic cell counts (SCCs) levels indicate the occurrence of infections in goat udders and are related to the productivity of goat milk, cheese and yoghurt. This work presents a segmentation method for counting somatic cells in goat milk images, intending to detect an infection known as mastiffs, which is the major cause of loss in dairy farming. The image segmentation procedure is devised by using the lab color space and the watershed transform. A large number of samples under variable preparation conditions are treated with the proposed method. A comparison between manual and the proposed technique is presented. Promising results indicates that video-microscopy systems may be employed to develop automated SCC for goat milk. 相似文献
917.
Short communication: Estrus synchronization using progestogens or cloprostenol in tropical hair sheep 总被引:1,自引:1,他引:0
Alejandro Alavez Ramírez Jaime Arroyo Ledezma Ruben Montes Pérez Roberto Zamora Bustillos Luis Fernando Navarrete Sierra Hector Magaña Sevilla 《Tropical animal health and production》2014,46(8):1515-1518
The objective of the experiment was to compare the use of a PGF2α analogue (Cloprostenol) IM, with an intravaginal progestagen sponge, flurogestone acetate (FGA), and equine chorionic gonadotropin (eCG) IM application protocol. A total of 30 cyclical hair ewes (54.07?±?0.5 kg live weight, body condition score 3.5?±?0.5, and age 3?±?1 years) were used. For the control group ewes (n?=?15), intravaginal sponges (IS) impregnated with 20 mg of FGA were inserted for 12 days with 500 IU of eCG IM at sponges withdrawal. For the PG group ewes (Treatment group n?=?15), two injections of Cloprostenol (75 mcg) were given 12 days apart. The presence of estrus was detected using two rams with 8 h interval beginning at the end of the treatment. Progesterone concentrations in blood were measured by solid phase radioimmunoassay. A student’s t test was performed to analyze the duration of estrus and the interval between the ends of the treatment and the onset of estrus (ET-OE) presentation. Progesterone levels were compared with two-way ANOVA, with treatment, and day of menstrual cycle as fixed factors. Treatment costs ratio was calculated by dividing the total costs of FGA IS application between total costs of Cloprostenol application. Significant differences (P?0.05) were found in the (ET-OE) interval and estrus duration. For the control group, estrus was presented at 30?+?8.2 h; in treatment group, at 44 h after the last application, duration of estrus was 54.9?+?8.34 h, and 41?+?1.83 h for the control and treatment group, pregnancy rates were 53.3 and 60.0 %, respectively. Significant differences (P?0.001) were found from days 9 to 13 on Progesterone levels in both treatments. Treatment costs of Cloprostenol protocol were 2.63 cheaper than FGA including disposable material, biological products, and labor. It was concluded that Cloprostenol could be an effective tool in estrus synchronization in hair sheep in tropical areas. 相似文献
918.
Carolina Corrêa de Figueiredo Monteiro Airon Aparecido Silva de Melo Marcelo Andrade Ferreira José Mauricio de Souza Campos Julyana Sena Rodrigues Souza Evannielly Thuanny dos Santos Silva Rafael de Paula Xavier de Andrade Emmanuelle Cordeiro da Silva 《Tropical animal health and production》2014,46(7):1149-1154
The aim of this study was to evaluate the replacement effect of wheat bran with spineless cactus and urea in heifers. Twenty-four heifers with an average initial weight of 185?±?13 kg were used in this experiment. Four levels of spineless cactus corrected with urea and ammonium sulfate (9:1) were studied: 0, 33, 66, and 100 % replacement with wheat bran. Samples of feed, orts, and feces were analyzed to estimate the intake and digestibility of dry matter (DM) and nutrients. Indigestible neutral detergent fiber was used as an internal marker. The experiment was conducted in a completely randomized design. Dry matter, neutral detergent fiber, and total digestible nutrient intake demonstrated a quadratic effect (P?0.05). Rumen degradable protein intake increased linearly (P?0.05). The maximum DM digestibility was estimated to be 0.67 with a 43 % replacement. Crude protein and NDF digestibility increased linearly (P?0.05). The total body weight gain and average daily gain decreased linearly with the replacement. Thus, it is practical to replace wheat bran with spineless cactus containing urea and ammonium sulfate up to 66 % in sugar cane-based diets. 相似文献
919.
Assessment of the metabolic,protein, energy,and liver profiles of lambs finished in a feedlot and receiving diets containing groundnut cake 总被引:1,自引:0,他引:1
Maria Leonor Garcia Melo Lopes de Araujo Gleidson Giordano Pinto de Carvalho Maria Consuêlo Caribé Ayres Lais Santana Bezerra Rodolpho Almeida Rebouças Carlos Humberto da Costa Vieira Filho Ronaldo Lopes Oliveira Thadeu Mariniello Silva Juliana Kelly Conceição Leite Catarine Stefane da Costa Teixeira 《Tropical animal health and production》2014,46(2):433-437
Forty-five crossbred Dorper × Santa Inês lambs were selected to assess the effect of replacing soybean meal by groundnut cake metabolic profile and histopathological evaluation of the kidney and liver tissues. The animals were 5 months old on average with a 24.5?±?5.3 kg initial body weight which were maintained fed in feedlot with groundnut cake (0, 25, 50, 75, and 100 %) as the replacement for soybean meal. Confinement lasted 84 days, and on the last day, the animals were fasted and slaughtered. A completely randomized design with five treatments and nine repetitions was used. Blood samples were collected from the jugular vein of each animal to evaluate the metabolic, protein, energy, and liver profiles of lambs. No effect was observed on protein, energy, or enzymatic profiles, which remained within the normal range for sheep. A histopathological examination was performed, and no deleterious effects from groundnut cake were observed in the liver or kidney tissues. Groundnut cake as a replacement for soybean meal can be used as an alternative protein source up to 100 % because it does not affect the metabolic, protein, and energy profiles or the liver and kidney functions of the growing sheep for slaughter. 相似文献
920.