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排序方式: 共有350条查询结果,搜索用时 15 毫秒
291.
In North America, the spatio-temporal scale of deforestation has resulted in a 94% decrease in temperate forests within 360 years. Despite the enormous scale of this disturbance, agriculture is so pervasive in modern society that its impacts are highly underappreciated. We investigated the impact of current agricultural practices on a disturbance-dependent species in southern Québec, Canada. Of 30 wood turtles (Glyptemys insculpta) followed via radio-telemetry, 20% died as a result of agricultural activities. Anthropogenic mortality estimates for adults and juveniles in 1998 were 0.10 and 0.18, respectively. For 1999, these values were 0.13 and 0.17, respectively. Of those turtles that survived, many had injuries inflicted by agricultural machinery. Sub-lethal mutilation rates for adults were 90 ± 3% in both years, whereas the maximum frequency for juveniles was 57%. A Carapace Mutilation Index was derived to quantify the distribution and severity of injuries observed. Only male and juvenile Carapace Mutilation Index values differed significantly. Adults had significantly more carapace injuries and limb amputations on their right sides. This bilateral asymmetry of injuries resulted from of a combination of turtle flight behavior and traditional harvesting practices. We reiterate the recommendations of forage researchers: setting the cutting height of disc mowers to 100 mm increases harvest yields, reduces wear on machinery, and decreases soil erosion. A by-product of such a change in cutting height is that turtle mortality and injury rates should be reduced, as wood turtle carapace height is <87 mm. Without changes in agricultural practices, this population will be extirpated. 相似文献
292.
Núñez Sellés AJ Vélez Castro HT Agüero-Agüero J González-González J Naddeo F De Simone F Rastrelli L 《Journal of agricultural and food chemistry》2002,50(4):762-766
An aqueous decoction of mango (Mangifera indica L.) stem bark has been developed in Cuba on an industrial scale to be used as a nutritional supplement, cosmetic, and phytomedicine. Previously we reported its antioxidant activity, and we concluded that the product could be useful to prevent the production of reactive oxygen species and oxidative tissue damage in vivo. A phytochemical investigation of mango stem bark extract has led to the isolation of seven phenolic constituents: gallic acid, 3,4-dihydroxy benzoic acid, gallic acid methyl ester, gallic acid propyl ester, mangiferin, (+)-catechin, (-)-epicatechin, and benzoic acid and benzoic acid propyl ester. All structures were elucidated by ES-MS and NMR spectroscopic methods. Quantitative analysis of the compounds has been performed by HPLC, and mangiferin was found to be the predominant component. Total polyphenols were assayed also by the Folin-Ciocalteu method. The free sugars and polyols content was also determined by GC-MS. 相似文献
293.
Van paemel MR De Rycke H Millet S Hesta M Janssens GP 《Journal of agricultural and food chemistry》2005,53(6):1873-1877
The contents of transition metal ions iron, copper, zinc, and manganese were simultaneously determined in pig feed using an ion chromatographic technique (IC) preceded by dry ashing. Employing ion exchange, the ions were separated on an IonPac CS5A column used in combination with a pyridine-2,6-dicarboxylic acid based eluent. The separation was followed by spectrophotometric detection after postcolumn reaction with 4-(2-pyridylazo)resorcinol. Dry ashing parameters were varied to assess their role in potential analyte loss. Quantitative recoveries (>95%) were obtained for all analytes with a dry ashing method that included a moderate temperature-time regime and ash leaching support in the form of sonication and heat treatment. The use of HCl as leaching acid and the presence of alkaline earths in the matrix solution did not interfere with the chromatographic separation. 相似文献
294.
Peñalvo JL Heinonen SM Nurmi T Deyama T Nishibe S Adlercreutz H 《Journal of agricultural and food chemistry》2004,52(13):4133-4138
The presence of plant lignans in 14 different soy-based health supplements is reported here for the first time together with the analysis of the isoflavone content, for which these products are commercialized. Six plant lignans, i.e., secoisolariciresinol, matairesinol, syringaresinol, lariciresinol, isolariciresinol, and pinoresinol, have been identified and quantified by gas chromatography-mass spectrometry, and a positive correlation has been found between the levels of plant lignans and the levels of isoflavones in the different products. Additional quantification of plant lignans and isoflavones in soybeans has been carried out, and results are provided to allow the comparison of the average levels in soybeans and soy-based supplements. 相似文献
295.
Lenwood W. Hall Jr. Steven J. Bushong Michael C. Ziegenfuss W. Edward Johnson Roger L. Herman David A. Wright 《Water, air, and soil pollution》1988,39(3-4):365-376
Chronic tributyltin toxicity experiments were conducted with the following Chesapeake Bay organisms: amphipod, Gammarus sp.; juvenile Atlantic menhaden, Brevoortia tyrannus and larval inland silverside, Menidia beryllina. TBT concentrations ranging from 29 to 579 ng L?1 did not significantly affect survival of the benthic amphipod, Gammarus sp. after 24-d exposures. The weight of Gammarus exposed to control conditions was 2.8 times greater than the weight of these test organisms exposed to 579 ng L?1 TBT. Twenty-eight day exposures to TBT concentrations of 93 and 490 ng L?1 did not significantly affect survival of juvenile B. tyrannus or larval M. beryllina. Histological examinations of B. tyrannus did not demonstrate absolute effects resulting from TBT exposure due to extensive variation between individuals. Various morphometric measurements of M. beryllina after TBT exposure did not demonstrate significant effects. However, significant reductions in growth were reported for M. beryllina at both TBT concentrations. Environmental concentrations of TBT in Chesapeake Bay and possible effects on the above biota are discussed. 相似文献
296.
Moreno-Franco B García-González Á Montero-Bravo AM Iglesias-Gutiérrez E Úbeda N Maroto-Núñez L Adlercreutz H Peñalvo JL 《Journal of agricultural and food chemistry》2011,59(18):9827-9834
The intake of alkylresorcinols and lignans in Spain is unknown due to the lack of information on the content of these compounds in particular foods. This paper describes the development of the first alkylresorcinol and lignan database adapted to the Spanish diet, including foods items especially relevant for this population. The values of alkylresorcinols and lignans in common foods and beverages were collected from scientific publications in refereed journals, and other foods particularly consumed in Spain, for which values were not available, were analyzed by standardized protocols and included into the database. The Alignia database presents the content of alkylresorcinols in 88 food items and the lignan content of 593 foods and beverages. Using the database, the intake of lignans in Spain, calculated using data from the Food Composition Panel based on household consumption, was estimated to be 0.76 mg/day. 相似文献
297.
298.
González JF Hernández A Meeusen EN Rodríguez F Molina JM Jaber JR Raadsma HW Piedrafita D 《Veterinary parasitology》2011,178(3-4):286-292
Canaria Hair Breed (CHB) sheep are more resistant than Canaria sheep (CS) to experimental Haemonchus contortus infection. Protective responses appear effective against the adult stage of the parasite, not as commonly reported in other breeds against the larval stages. In this study we have quantified several abomasal immune cells and correlated these with parasitological variables for each breed. A significant negative correlation between CD4+ T cell numbers and worm burden or length at 28 dpi was seen only in CS sheep. Significant negative correlations for both abomasal eosinophils and γδ/WC1+ T cells, and fecundity of the adult worms were observed only in the resistant CHB sheep breed. Tissue eosinophils and γδ/WC1+ T cells were positively correlated in CHB sheep. We suggest that the two sheep breeds have disparate immune responses following infection with the parasite and that γδ+ T cells in association with eosinophils may play a hitherto unrecognised role in modulating fecundity in H. contortus adult female parasites. 相似文献
299.
ABSTRACT: Several alphaherpesviruses breach the basement membrane during mucosal invasion. In the present study, the role of proteases in this process was examined. The serine protease-specific inhibitor AEBSF inhibited penetration of the basement membrane by the porcine alphaherpesvirus pseudorabies virus (PRV) by 88.1% without affecting lateral spread. Inhibitors of aspartic-, cysteine-, and metalloproteases did not inhibit viral penetration of the basement membrane. Further analysis using the Soybean Type I-S trypsin inhibitor for the serine protease subcategory of trypsin-like serine proteases resulted in a 96.9% reduction in plaque depth underneath the basement membrane. These data reveal a role of a trypsin-like serine protease in PRV penetration of the basement membrane. 相似文献
300.
Poverty and biodiversity trade-offs in rural development: A case study for Pujiang county,China 总被引:1,自引:0,他引:1
Huib Hengsdijk Wang Guanghuo Marrit M. Van den Berg Wang Jiangdi Joost Wolf Lu Changhe Reimund P. Roetter Herman Van Keulen 《Agricultural Systems》2007
Both, poverty reduction and preservation of biodiversity are high on the global agenda on sustainable development. The relationships between poverty, biodiversity of agro-ecosystems and agricultural development are complex and poorly understood. In this paper, we present an integrated framework for analysis of agricultural development and natural resource management options at agro-ecosystem level, using Pujiang county, in Zhejiang province, China as a case study area to perform the analysis. A regional linear programming (LP) model is applied, maximizing regional economic surplus, given production and labour market conditions in Pujiang. We use the model to examine the consequences for a set of regional poverty and biodiversity indicators, of four so-called poverty reduction strategies, i.e., (i) intensification of production, (ii) diversification towards livestock production, (iii) land expansion, and (iv) an exit from agriculture. The analysis indicates that diversification is the most promising poverty reduction strategy, but requires efficient use of animal manure in cropping systems to avoid environmental problems. Improved nutrient management in cropping systems is effective in reducing the regional nitrogen surplus, but less effective in increasing per capita income. The exit strategy is effective in reducing poverty and achieving biodiversity goals, but may have important social consequences that are not addressed in this study. Further reduction in rural poverty is hampered by labour constraints during the harvesting period in high value crops such as vegetables and fruits, which calls for research and development in the field of agricultural mechanization. 相似文献