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971.
Arturo Carabalí James Montoya-Lerma Anthony C Belloti Martin Fregene Gerardo Gallego 《农业科学学报》2013,12(12):2217-2228
Genes resistant to Aleurotrachelus socialis were transferred to the F1 from the interspecific hybrid wild species of Manihot flabellifolia to M. esculenta and two advanced generations of backcrosses (BC1 and BC2). We characterized the resistance of A. socialis transferred to BC2 parents (CW67-160, CW67-130, CW67-44), MTAI-8 (BC1), resistant (CMB9B-73) and susceptible (CMB9B-104) genotypes from contrasting pools, and resistant (MEcu-72) and susceptible (CMC-40) genotypes. Whitefly demography and biology were evaluated. SSR molecular markers associated with a phenotypic response of plant resistance were detected in segregating populations (BC2). Results showed that although female survival time was similar on all hosts, the lowest averages of longevity, fecundity and oviposition rate were observed in the resistant control MEcu-72, only being significantly similar to the parent CW67-130. When the BC1 and BC2 populations were compared, it was found that A. socialis fecundity was eight times lower on CMB9B-73 progeny than on CW67-130, expressing the highest levels of resistance to the whitefly. Ten genotypes of CMB9A and CMB9B family had the best segregation. A total of 486 microsatellite primers were evaluated using bulked segregant analysis (BSA), 11 showed polymorphism between the contrasting pools and only one showed significant differences between resistant and susceptible individuals. In conclusion, fecundity was the parameter that impacted most on the intrinsic rate of A. socialis population growth. 相似文献
972.
Mota-Sanchez D Cregg B Hoffmann E Flore J Wise JC 《Journal of agricultural and food chemistry》2012,60(12):2958-2966
Infinite- and finite-dose laboratory experiments were used to study the penetrative and dislodgeable residue characteristics of (14)C-insecticides in apple fruit. The differences in dislodgeable and penetrated residues of three radiolabeled insecticides ((14)C-thiamethoxam, (14)C-thiacloprid, and (14)C-indoxacarb), applied in aqueous solution with commercial formulations, were determined after water and methanol wash extractions. The rate of sorption and extent of penetration into the fruit cuticles and hypanthium of two apple cultivars were measured after 1, 6, and 24 h of treatment exposure, using radioactivity quantification methods. For all three compounds, 97% or more of the treatment solutions were found on the fruit surface as some form of non-sorbed residues. For indoxacarb, sorption into the epicuticle was rapid but desorption into the fruit hypanthium was delayed, indicative of a lipophilic penetration pathway. For the neonicotinoids, initial cuticular penetration was slower but with no such delay in desorption into the hypanthium. 相似文献
973.
A novel analytical method using fast gas chromatography-surface acoustic wave detection (FGC-SAW) was employed to rapidly characterize blueberry volatile profiles according to genotypes and fruit maturity. Fourteen FGC-SAW peaks were observed and 11 peaks were tentatively identified in the 15 s chromatogram. Peak identifications were confirmed by matching retention index values with similar values from GC-MS analyses of the same samples. Eighty peaks were observed in the 40 min GC-MS analysis of identical samples. Principal component analysis (PCA) score plots of FGC-SAW and GC-MS data both differentiated blueberries according to genotype, maturity stage, and harvest date even though FGC-SAW PCA's used far fewer peak area values. PCA plots clearly separated 'FL02-40', 'Snowchaser', 'Jewel', and 'Primadonna' blueberry cultivars into four quarters using two-dimensional PCA projections. FGC-SAW was also successful in differentiating three berry maturity stages in PCA score plots for both 'Jewel' and 'Primadonna' cultivars. FGC-SAW is an effective technique for rapid analysis of major blueberry volatiles, but could not determine many mid- and low-level volatiles as they were often coeluted with higher concentration volatiles. 相似文献
974.
DS Grum D Cook DR Gardner JM Roper JA Pfister MH Ralphs 《Journal of agricultural and food chemistry》2012,60(33):8083-8089
Locoism is a toxic syndrome of livestock caused by the ingestion of a subset of legumes known as locoweeds endemic to arid and semiarid regions of the western United States. Locoweeds contain the toxic alkaloid swainsonine, which is produced by the endophytic fungi Undifilum species. Two chemotypes of plants can coexist within toxic populations of locoweeds: chemotype 1 plants are defined as individuals containing swainsonine concentrations greater than 0.01% and quantitatively greater amounts of Undifilum, while chemotype 2 plants are defined as individuals containing less than 0.01% swainsonine and quantitatively smaller amounts of Undifilum. To elucidate the mechanisms that govern chemotypes, the amount of Undifilum in seeds/embryos was manipulated, thus altering subsequent swainsonine concentrations in three locoweed species: Astragalus mollissimus, Astragalus lentiginosus, and Oxytropis sericea. Chemotype 1 seeds that were fungicide-treated or had the seed coat removed resulted in plants with swainsonine concentrations comparable to those in chemotype 2 plants. Conversely, embryos from seeds of chemotypes 1 and 2 that were inoculated with the endophyte resulted in plants with swainsonine concentrations comparable to those of chemotype 1 plants. This reproducible interconversion between the two swainsonine chemotypes suggests that the quantity of endophyte present in the seed at the time of germination is a key determinant of the eventual chemotype. Additionally, this is the first report of the inoculation of locoweeds with the endophyte Undifilum species. 相似文献
975.
James A. Entry 《Water, air, and soil pollution》2012,223(9):6109-6121
The Loxahatchee National Wildlife Refuge (Refuge) developed as a system with waters low in nutrients. Today, the Refuge wetlands are impacted by inflows containing elevated nutrient concentrations originating from agricultural sources. We analyzed water quality sampled at 54 sites in the Refuge. The Refuge was divided into northern, central, and southern latitudinal areas and then perimeter, transition, and the interior zones based on distance from the canal towards the Refuge interior. In the perimeter zone, total dissolved solids (TDS), silicon (Si), and total phosphorus (TP) concentrations in water were higher in the northern than the central area and TDS, Si, SO4, and TP concentrations in water were higher in the central than the southern area. In general TDS, Ca, Cl, Si, SO4, and TP loads in the northern perimeter, transition, and interior zones decreased from 2005 to 2009. The decrease is less pronounced in the central and southern areas than the northern area. As water flowed southward for over 30?km from the northern to the southern area in the perimeter zone, most water quality parameters analyzed were reduced in the water column. However, large amounts of Ca and Cl were added to the water column indicating that canal water is continually diffusing and intruding into the Refuge in all zones. In the perimeter zone, and to a lesser degree in the transition zone, the Refuge has accumulated substantial amounts of Ca, Si, SO4, and TP in vegetation and soils during the sampling period. 相似文献
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980.
D. T. Westermann T. A. Tindall D. W. James R. L. Hurst 《American Journal of Potato Research》1994,71(7):417-431
Potassium and N fertilization is often required for maximum potato (Solanum tuberosum L.) production. Nitrogen, K, and K-sources (KCl, K2SO4 are known to affect yield and quality of potatoes but N and K interactions as affected by K-source have not been defined. This study evaluated the N*K and K-source interactions on Russet Burbank tuber yields and specific gravity (SG) in two irrigated field experiments. Nitrogen rates of 0, 112, 224 or 336 kg ha-1 were combined with selected K rates of 0,112, 224 or 448 kg ha-1 as either KC1 or K2SO4 in an incomplete factorial. A multiple linear regression model was fit to the data and used to predict yield and SG for a complete factorial for each K-source. Both N and K applications increased yields independent of K-source. Nitrogen decreased yields at the 336 kg ha-1 rate. Potassium increased yields up to 448 kg K ha-1. Both K-sources decreased SG a similar amount with N application; without N, KC1 decreased SG but K2SO4 did not. Nitrogen also decreased SG. Petiole NO3-N and K concentrations were positively related to yields and negatively to specific gravities. The petiole K concentration 100 days after planting should be above 4.5 for highest tuber yields. The N*K*K-source interaction was important for yields at low available N and for SG at adequate N availabilities. This study showed that N or K fertilizers can be applied according to their respective soil test concentration and the crop’s requirement, generally without consideration of K-source. 相似文献