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排序方式: 共有163条查询结果,搜索用时 15 毫秒
131.
132.
J. B. Valente F. S. Pereira L. A. Stempkowski M. Farias P. Kuhnem D. Lau T. V. M. Fajardo A. Nhani Junior R. T. Casa A. Bogo F. N. da Silva 《Plant pathology》2019,68(3):588-600
Soilborne wheat mosaic disease (SBWMD), originally attributed to infections by Soilborne wheat mosaic virus (SBWMV) and Wheat spindle streak mosaic virus (WSSMV), is one of the most frequent virus diseases and causes economic losses in wheat in southern Brazil. This study aimed to characterize molecularly the viral species associated with wheat plants showing mosaic symptoms in Brazil. Wheat leaves and stems displaying mosaic symptoms were collected from different wheat cultivars in Passo Fundo municipality, Rio Grande do Sul State, southern Brazil. Double-stranded RNA was extracted and submitted to cDNA library synthesis and next-generation sequencing. No sequences of SBWMV and WSSMV were detected but the complete genome sequence of a putative new member of the family Benyviridae was determined, for which the name wheat stripe mosaic virus (WhSMV) is proposed. WhSMV has a bipartite genome with RNA 1 and RNA 2 organization similar to that of viruses belonging to Benyviridae. WhSMV RNA 1 has a single open reading frame (ORF) encoding a polyprotein with putative viral replicase function. WhSMV RNA 2 has six ORFs encoding the coat protein, the major protein (read-through), triple gene block movement proteins (TGB 1, 2 and 3) and ORF 6 (hypothetical protein). In addition to the genomic organization and nucleotide and amino acid sequence identities, phylogenetic analyses also corroborated that WhSMV is a virus species of the Benyviridae. However, isolates of WhSMV formed a clade distinct from members of the genus Benyvirus. It was also demonstrated that the plasmodiophorid Polymyxa graminis is associated with wheat roots showing SBWMD symptoms and infected by WhSMV. 相似文献
133.
Ricardo Siqueira da Silva João Rafael Silva Soares Izailda Barbosa dos Santos Mirian Filgueira Pimentel Elizeu de Sá Farias Júlio Cláudio Martins 《国际虫害防治杂志》2019,65(1):10-15
Oligonychus ilicis (McGregor) (Acari: Tetranychidae), is one of the most important mite pests found in coffee plants. One way to reduce intensive pest attacks is management via resistant plants. The purpose of this study was to evaluate the resistance of 14 C. canephora genotypes to O. ilicis by antixenosis and antibiosis mechanisms and to determine the preimaginal conditioning effect on resistant genotypes using O. ilicis reared on C. canephora. Resistance by antixenosis was not found; however, nine genotypes showed resistance to O. ilicis via an antibiosis mechanism. Two of these resistant genotypes showed a more persistent resistance than the O. ilicis reared on C. canephora, which indicated that a previous host can affect the selection of a genotype by O. ilicis. The study may provide a model to evaluate the preimaginal conditioning effect on plant resistance, which can be useful for plant breeders. 相似文献
134.
Tadeu B.M. SilvaHerbert A.A. Siqueira Alexandre C. OliveiraJorge B. Torres José V. OliveiraPedro A.V. Montarroyos Maria J.D.C. Farias 《Crop Protection》2011,30(9):1156-1161
The cotton leaf worm, Alabama argillacea, is a key cotton pest in Brazil and is managed with repeated insecticide applications. Reports of insecticide control failures have recently increased, particularly with pyrethroids. The present work assessed the resistance status of A. argillacea to a number of different insecticides currently used in cotton crops. Bioassays were conducted to estimate the response of 2nd-instar A. argillacea populations to deltamethrin, chlorpyrifos, endosulfan, abamectin and spinosad. A leaf dip bioassay with diluted insecticide formulations was performed in the laboratory with five to nine populations depending on the insecticide. LC50 values were estimated by probit analysis after correction for control mortality data and used to calculate the resistance ratios (RR). All assessed populations exhibited varied and significant levels of resistance to all insecticides tested, but only moderate levels of resistance to deltamethrin were observed (RR = 52.3). The LC50 values for deltamethrin were higher than 30 mg/l for most populations, and above the field rate (12.5 mg/l). This suggests that the frequency of resistant individuals in these populations was likely above the critical frequency. There was low to moderate resistance to abamectin, chlorpyrifos, endosulfan and spinosad formulations (the highest RRs observed were 4.2, 8.4, 11.1 and 23.5, respectively). Despite the moderate levels of resistance to pyrethroids in A. argillacea, overall results indicate the presence of low to moderate resistance of A. argillacea to insecticides currently used against cotton pests in Brazil. 相似文献
135.
Monasterio RP Londonio JA Farias SS Smichowski P Wuilloud RG 《Journal of agricultural and food chemistry》2011,59(8):3566-3574
A novel method has been developed to determine As-containing animal feed additives including roxarsone (ROX), p-arsanilic acid (p-ASA) and nitarsone (NIT), as well as other organic As species (dimethylarsonic acid (DMAA) and monomethylarsonic acid (MMAA)) by ion-pairing high-performance liquid chromatography coupled to hydride generation atomic fluorescence spectrometry (IP-HPLC-HG-AFS). A simple isocratic reversed-phase (RP) HPLC method with a mobile phase containing citric acid and sodium hexanesulfonate (pH 2.0) was developed using a C(18) column. The use of an organic solvent free mobile phase turns this methodology into an environmentally friendly alternative. Several ion pair forming agents, such as sodium hexanesulfonate, tetrabutylammonium bisulfate and perfluoroheptanoic acid, were studied. The limits of detection for As species were calculated in standard solution and resulted to be 0.2, 0.5, 0.6, 1.6, and 1.6 μg As L(-1) for MMAA, DMAA, p-ASA, ROX and NIT, respectively. This method exhibited convenient operation, high sensitivity and good repeatability. It was applied to As speciation in different samples including arugula, dog food, dog urine and chicken liver. 相似文献
136.
Ana D. B. Baia Adriano M. F. Silva Bárbara G. Ribeiro Claudeana C. Souza Wilson J. Silva Júnior Valdir Q. Balbino Carla M. Leal Antônio R. G. de Farias Elineide B. Souza Marco A. S. Gama 《Plant pathology》2021,70(3):521-533
Burkholderia cepacia was originally described as the causal agent of onion sour skin. However, this bacterium is now recognized as a complex of 22 closely related species, commonly referred to as the B. cepacia complex (BCC). Only a few taxonomic studies have been undertaken with the aim of understanding the diversity of species associated with onion sour skin. In this study, we used a polyphasic analysis including rep-PCR assay, biochemical and pathological profiles, and multilocus sequence analysis (MLSA) to characterize the BCC species associated with onion sour skin in the semi-arid region of north-east Brazil. Phylogenetic analysis of the recA of strains representing the genetic variability, as determined by rep-PCR, grouped the strains into four clades. Clades I and II represent B. cenocepacia lineages IIB and IIIA, respectively, while the strains in Clades III and IV clustered more closely to Clades I and II than to strains of any other BCC species. MLSA confirmed the existence of the four clades with a 1.00 posterior probability. A distance matrix indicated a low level of divergence among the strains of the four clades found in the MLSA, proving that B. cenocepacia lineages IIIA, IIIB, and a new lineage of B. cenocepacia are associated with onion sour skin in the semi-arid region of north-east Brazil. Also, surprisingly, no strain was identified as B. cepacia, indicating that this species probably does not play a role in this disease in this region. 相似文献
137.
Daniela Bernadete Rozza Ingrid Vervuert Josef Kamphues Cláudio Estêv?o Farias da Cruz David Driemeier 《Journal of veterinary diagnostic investigation》2006,18(5):494-496
The consumption of monensin-containing feed resulted in deaths of water buffaloes from a feedlot in which cattle and buffaloes were kept together. The monensin formulation was recommended only for use in cattle. Anorexia, muscular weakness, dyspnea, and recumbency were the major clinical findings. The most significant gross lesions were focal pale areas in semitendinosus and semimembranosus muscles, in which segmental necrosis of myofibers was seen microscopically. To compare susceptibilities of species to monensin, 3 bovine calves and 3 buffalo calves were orally dosed. At 5, 7.5, and 10 mg/kg of monensin, only the buffaloes became ill and died. Clinical signs initiated 18-20 h postdosing and were comparable to those from field cases. Gross changes consisted of ascites, hydrothorax, hydropericardium, hepatomegaly, and focal pale areas in the myocardium and to a lesser degree in semitendinosus and semimembranosus muscles. Histopathological changes also resembled those from the field cases, but were especially pronounced in the myocardial cells. The hypothesis that buffaloes could have a lower tolerance to monensin than cattle has been supported by experimental cases. 相似文献
138.
Garcia GD Carvalho MA Diniz CG Marques JL Nicoli JR Farias LM 《British poultry science》2012,53(1):71-76
1. The objective was to evaluate the occurrence of cultivable components of the Bacteroides fragilis group in faeces of broiler chickens and their antimicrobial susceptibility patterns. 2. Faecal samples of 36?×?45-d-old Cobb broilers of both sexes from 15 different flocks on one farm were diluted 10-fold and plated on to Bacteroides-bile-esculin agar for colony count and isolation. Identification was by molecular methods and antimicrobial susceptibility in the agar dilution assay. 3. A total of 236 isolates was recovered from a mean population of 3·32?×?107 colony-forming units/g of faeces. B. fragilis was shown to be the predominant Bacteroides species (45·3%), followed by B. distasonis (35·6%), B. vulgatus (8·9%), B. ovatus (2·5%) and B. stercoris (1·3%). 4. Among 204 bacterial isolates tested, high resistance to ampicillin (98·5%), norfloxacin (95·1%) and tetracycline (88·2%) were observed. High (89·7%) multi-drug resistance was observed to 3–7 of the tested drugs. 5. Components of the B. fragilis group were sub-dominant in broiler faecal microbiota, with a different species pattern compared with human and high antimicrobial multi-drug resistance. 相似文献
139.
Farias Nadja Naiara Pereira Freitas Ednardo Rodrigues do Nascimento Germano Augusto Jerônimo Xavier Regina Patrícia Souza de Melo Braz Nádia Dantas Francisco Diego Teixeira Figueiredo Carlos Weiber Silva Gomes Valter Luis Maia Watanabe Pedro Henrique 《Tropical animal health and production》2019,51(1):179-185
Tropical Animal Health and Production - The aim of the current study was to evaluate the addition of fresh and stored copra meal to the diet of meat quails. Two hundred eighty-seven-day-old male... 相似文献
140.
Souza TM Cunha AP Farias DF Machado LK Morais SM Ricardo NM Carvalho AF 《Pest management science》2012,68(10):1380-1384
BACKGROUND: Myracrodruon urundeuva Fr. Allemao is a common tree in the Caatinga that has been widely used for various medical purposes. Previous studies showed that the ethanol seed extract of M. urundeuva has potent activity against the larval stage of the dengue vector Aedes aegypti. Given this potential insecticidal activity, bioguided separation steps were performed in order to isolate the active compound(s). RESULTS: The isolation process resulted in only one active chemical compound, identified by infrared spectroscopy and mass spectrometry as m-pentadecadienyl-phenol. This compound presented potent larvicidal and pupicidal activity (LC50 10.16 and 99.06 µg mL−1 respectively) and great egg hatching inhibitory activity (IC50 49.79 µg mL−1). The mode of action was investigated through observations of behavioural and morphological changes performed in third-instar larvae treated with m-pentadecadienyl-phenol solution after 1, 6, 12, 16 and 20 h of exposure. Some changes were observed as flooding of the tracheal system, alterations in siphonal valves and anal gills and lethargy, probably caused by the strong anticholinesterasic activity reported previously. CONCLUSION: The compound isolated from M. urundeuva seeds, m-pentadecadienyl-phenol, showed potent activity against immature stages of dengue vector, Ae. aegypti, being considered the main larvicidal principle. Copyright © 2012 Society of Chemical Industry 相似文献