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51.
Development of a PCR test to diagnose Haemophilus parasuis infections. 总被引:30,自引:0,他引:30
A polymerase chain reaction (PCR) test was developed in order to improve the accuracy and speed of diagnosis of Haemophilus parasuis, an economically important respiratory pathogen that affects swine. The gene sequence of the 16S small subunit ribosomal RNA of H. parasuis (GenBank M75065) was compared with 56 16S sequences of related bacteria, including those frequently isolated from pig tissues. Two species-specific primers were designed: HPS forward and HPS reverse. The predicted size of the amplified PCR product was 821 bp. The PCR test could detect a minimum of 102 bacteria and 0.69 pg of DNA. Thirty-one H. parasuis isolates, including 12 different serovars and 19 field isolates, were positive using the PCR test. No amplification was observed when the test was run using DNA from 15 other bacterial species commonly isolated from swine tissues. A weak band was observed when the PCR test was performed using Actinobacillus indolicus DNA as template. Clinical samples tested by PCR included tissues and swabs from 5 animals naturally infected with H. parasuis and 1 experimentally infected animal. The PCR was positive in 26 of 30 clinical samples. Four samples showed weak bands, and these results were not considered positive. Haemophilus parasuis was isolated from 18 of 30 of these samples. Tissues from specific pathogen-free (SPF) pigs and from unrelated species were negative for H. parasuis isolation and PCR. The developed PCR was successfully used in the diagnosis of H. parasuis infection, especially when compared with traditional microbiology techniques. 相似文献
52.
Alder MN Rogozin IB Iyer LM Glazko GV Cooper MD Pancer Z 《Science (New York, N.Y.)》2005,310(5756):1970-1973
Instead of the immunoglobulin-type antigen receptors of jawed vertebrates, jawless fish have variable lymphocyte receptors (VLRs), which consist of leucine-rich repeat (LRR) modules. Somatic diversification of the VLR gene is shown here to occur through a multistep assembly of LRR modules randomly selected from a large bank of flanking cassettes. The predicted concave surface of the VLR is lined with hypervariable positively selected residues, and computational analysis suggests a repertoire of about 10(14) unique receptors. Lamprey immunized with anthrax spores responded with the production of soluble antigen-specific VLRs. These findings reveal that two strikingly different modes of antigen recognition through rearranged lymphocyte receptors have evolved in the jawless and jawed vertebrates. 相似文献
53.
Microbial biomass C and soil respiration measurements were made in 17–20 yr old soils developed on sluiced and tipped coal‐combustion ashes. Topsoil (0–30 cm) and subsoil (30–100 cm) samples were collected from three soil profiles at two abandoned disposal sites located in the city area of Halle, Saxony‐Anhalt. Selected soil physical (bulk density and texture) and chemical (pH, organic C, total N, CEC, plant available K and P, and total Cd and Cu) properties were measured. pH values were significantly lower while organic C and total N contents and the C : N ratio were significantly higher in the topsoil than in the subsoil indicating the effects of substrate weathering and pedogenic C accumulation. Likewise, microbial biomass C, K2SO4‐extractable C, and soil respiration with median values of 786 μg biomass C g–1, 262 μg K2SO4‐C g–1, and 6.05 μg CO2‐C g–1 h–1, respectively, were significantly higher in the topsoil than in the subsoil. However, no significant difference was observed in metabolic quotient between the topsoil and the subsoil. Metabolic quotient with median values of 5.98 and 8.54 mg CO2‐C (g biomass C)–1 h–1 for the 0–30 cm and 30–100 cm depths, respectively, was higher than the data reported in the literature for arable and forest soils. Microbial biomass C correlated significantly with extractable C but no relationship was observed between it and total N, Cd, and Cu contents, as well as plant‐available K and P. We conclude that the presence of the remarkable concentration of extractable C in the weathered lignite ashes allowed the establishment of microbial populations with high biomass. The high metabolic quotients observed might be attributed to the heavy‐metal contamination and to the microbial communities specific to ash soils. 相似文献
54.
Galina Gindin Tatiana Kuznetsova A. Protasov Nitza Saphir Z. Madar Z. Mendel 《Phytoparasitica》2008,36(5):472-482
The susceptibility of larvae ofThaumetopoea solitaria Freyer (Lepidoptera; Notodontidae, Thaumetopoeinae), fed on treated pistachio foliage, to three commercial control products
derived fromBacillus thuringiensis (Bt), was evaluated in the laboratory. Both Dipel DF and Delfin WG were highly effective against 1
st
and 2
nd
instar larvae at relatively low concentrations (LC50: 0.01–0.04%), whereas mortality of the 3
rd
instar larvae reached 50% only at a Dipel DF concentration of 0.2%. The third formulation, Foray 48B, was significantly less
toxic toward all tested larval instars. The susceptibility ofT. solitaria toBr decreased progressively between molts, and then increased steeply during the first days following each molt. Use of the film-forming
polymer Nu-Film as a wetting agent and spreader-sticker for the commercial formulation of Dipel DF improvedBt adhesion to extremely hydrophobic youngPistacia foliage, and significantly increasedBt persistence under ambient conditions. Addition of Nu-Film improved the leaf surface coverage and extended the duration of
rainproofing. 相似文献
55.
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57.
Effectiveness of dietary vitamin supplementation to the performance of common carp (Cyprinus carpio L.) larvae in intensive rearing condition 下载免费PDF全文
Zsuzsanna Jakab Sándor Zsuzsanna Bor Papp László Ardó Janka Nagy Biro Galina Jeney 《Aquaculture Research》2018,49(2):738-747
Study of enrichment of different vitamins (C, B1, B6 and E) in common carp larvae through 4 weeks feeding in recirculation system was carried out. For this purpose, procedure for enrichment of Artemia nauplii with different vitamins was developed and investigated the effectiveness in larvae nutrition. The habituation of larvae to dry feeds was done using supplemented dry diets with the same vitamins. To study the effect of vitamins in young fish, the most common stress situation was planned for carp nursed fries, which occurs during transportation. Levels of vitamins and parameters of immune response in mucus were monitored before and after stress situation. At the end of the feeding trials using enriched Artemia nauplii, level of vitamin B1, B6 and C were increased in the body of fish, but remained on similar level or decreased after dry feeding period. Therefore, we concluded that Artemia is a good delivery vector of these vitamins. While handling stress, vitamin C and E concentration was decreased and sparing effect of antioxidant vitamins was confirmed in groups supplemented with both vitamins. Vitamin B1 was consumed intensively during the stress, vigorously in groups without supplementation. Contrary to this, vitamin B6 level increased in stress condition in group without supplementations. The levels of immunoglobulins in mucus were increased in all treated groups independently of treatment. Our results confirm that carp larvae reared in tank condition needs sufficient amount of vitamins C, B1 and B6 supplements to protect them from the mild handling stress. 相似文献
58.
Elisabetta Gotor Mauricio R. Bellon Muhabbat Turdieva Karim Baymetov Parhod Nazarov Elena Dorohova-Shreder Vladislav Arzumanov Mikhail Dzavakyants Abduvahob Abdurasulov Galina Chernova Eugeniy Butkov Francesco Caracciolo 《Agroforestry Systems》2018,92(5):1253-1266
The aim of this paper is to analyze the impact of a set of interventions related to on-farm/in situ conservation and use of fruit species (cultivated and wild) on farmers’ livelihoods and species diversity in Central Asia. Specifically, a difference-in-differences propensity score matching is used to evaluate the outcome of a development research program in Uzbekistan between 2005 and 2010. Species crop diversity maintained by farmers before and after the project increased as a result of the interventions, showing the efficacy of the interventions promoted by the projects in terms of conservation. Furthermore, innovations provided by the program increased both household propensity of marketing and self-consumption of target fruit. However, the program’s interventions did not seem to impact significantly any of the indicators related to household livelihoods. The short time elapsed between the end of the project and the impact assessment may be too brief to capture any observable impact on livelihoods. 相似文献
59.
Leonardo J. Solmesky Avi Zrachya Galina Denisova Yedidya Gafni Jonathan M. Gershoni 《Phytoparasitica》2010,38(2):201-208
Tomato yellow leaf curl virus (TYLCV) is a begomovirus that seriously threatens tomato crops worldwide. Current immunodiagnostic methods for this pathogen
employ commercially produced mAbs raised against TYLCV. However, despite the existence of these mAbs, little information regarding
their characterization or strategy of production has been published. In addition, research on TYLCV would certainly benefit
were more mAbs available, thus allowing efficient examination of the virus life cycle, modes of pathogenesis and possibly
the development of resistant cultivars. The coat protein (CP) of TYLCV is the only known building block of the viral capsid.
Therefore, in this study we used CP as an immunogen for the production of novel mAbs. We employed a strategy in which the
CP was truncated at its C-terminus to avoid intra- and inter-protein interactions that could impair epitope exposure. For
the same reason, we used a denaturated antigen to expose linear epitopes during the immunization. This effort yielded three
mAbs: they were characterized biochemically and immunologically, and their epitopes were mapped. Possible applications of
these mAbs are discussed. 相似文献
60.
Alejandro Mendoza Daniel Cavestany Gonzalo Roig Julio Ariztia Claudia Pereira Alejandro La Manna David A. Contreras Carlos S. Galina 《Livestock Science》2010,127(1):60-66
The effect of restricted suckling on milk yield and composition, udder health, and postpartum anoestrus in dairy cows in pasture-based systems, was studied in 32 Holstein multiparous cows and their calves. At calving, each cow–calf pair was randomly assigned to one of two treatments: restricted suckling (RS) of the cows by her own or another calf, twice daily for 30 min or artificial rearing (AR) of the calves with milk obtained from the bulk tank, offered twice a day in buckets. Treatments were applied until week 8 after calving. The diet of the cows consisted of direct grazing in improved pastures, corn silage and a commercial concentrate which was offered at milking. Milk production and composition, udder health, body condition score of the cows, body weight and milk intake of the calves were measured weekly, and the first postpartum ovulation was determined three times a week by ovarian ultrasonography. Cows with RS management had a lower machine-milked milk yield (17.9 vs. 24.8 kg/d), a lower fat percentage (3.21 vs. 4.11%) and 4% fat-corrected milk yield (16.2 vs. 25.7 kg/d), and also a lower average milk flow (1.35 vs. 1.76 kg/min) than cows in the AR treatment. There was no effect of treatment on milk protein percentage or udder health as measured by milk electrical conductivity. The interval from calving to first postpartum ovulation was shorter in the AR cows than in the RS cows (18.5 vs. 21.8 days). The RS calves consumed more milk (7.2 vs. 5.4 kg/d), gained more body weight (0.813 vs. 0.656 kg/d), and had a higher body weight at weaning (84.3 vs. 73.3 kg) than AR calves. Restricted suckling of grazing dairy cows had a negative effect on machine-milked milk yield, fat percentage and 4% fat-corrected milk yield, but had no effect on udder health or on improved weight gain and body weight at weaning of the calves. 相似文献