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471.
Tavel L Andriot I Moreau C Guichard E 《Journal of agricultural and food chemistry》2008,56(21):10208-10217
Interactions between beta-lactoglobulin (BLG) in its monomeric form and a wide range of aroma compounds were investigated by Fourier transform infrared (FT-IR) and 2D nuclear magnetic resonance (NMR) spectroscopies. A screening of the ligands was carried out by FT-IR through the amide I region changes of BLG upon binding. The location of two binding sites was determined by 2D NMR from the study of 10 selected ligands with different structures. All of the data suggest at least two binding behaviors as a function of the chemical class, the hydrophobicity, or the structure of the ligands. The binding of the elongated aroma compounds, such as 2-nonanone or ethyl pentanoate, within the central cavity involves residues located at the entrance of the calyx and Trp19. The binding onto the protein surface of aroma compounds that have or adopt a compact structure occurs in a site located between strand beta-G, alpha helix, and strand beta-I. 相似文献
472.
Briard-Bion V Juaneda P Richoux R Guichard E Lopez C 《Journal of agricultural and food chemistry》2008,56(20):9374-9382
Increasing the knowledge on dietary fat composition, mainly the minor components, will improve the nutritional value of foods and their labeling. In this study, we examined the trans-octadecenoic acid (C18:1) composition of Emmental cheeses enriched in unsaturated fatty acids (FA) and manufactured with milks produced by cows selected to produce small and large fat globules. The FA composition of the milks was not significantly ( P > 0.05) different from the FA composition of the corresponding Emmental cheeses. Increasing the unsaturated FA content of the cheeses using dietary manipulations lead to an increase in the trans-C18:1 and changed their isomeric profiles. In milk fat produced with the linseed-enriched diet, the trans-10 C18:1 concentration was greater than trans-11 C18:1 (vaccenic acid), which is classically the major trans-C18:1 in milk fat. The content in trans-C18:1 and more particularly in trans-10 C18:1 was negatively correlated with the size of fat globules ( r (2) = 0. 82 and 0.87, respectively) and related to milk fat depression. The trans-C18:1 content was negatively correlated with the saturated FA (slope = -0.35; r (2) = 0.81) and positively correlated with the unsaturated (slope = 0.29; r (2) = 0.85) and monounsaturated (slope = 0.32; r (2) = 0.81) FA. Focusing on the health-related considerations of fat in food products, further nutritional studies are needed to elucidate the role of trans-C18:1 isomers. 相似文献
473.
Bursztyka J Debrauwer L Perdu E Jouanin I Jaeg JP Cravedi JP 《Journal of agricultural and food chemistry》2008,56(12):4832-4839
Vinclozolin is a dicarboxymide fungicide that presents antiandrogenic properties through its two hydrolysis products M1 and M2, which bind to the androgen receptor. Because of the lack of data on the biotransformation of vinclozolin, its metabolism was investigated in vitro in precision-cut rat liver slices and in vivo in male rat using [ (14)C]-vinclozolin. Incubations were performed using different concentrations of substrate, and the kinetics of formation of the major metabolites were studied. Three male Wistar rats were fed by gavage with [ (14)C]-VZ. Urine was collected for 24 h and analyzed by radio-HPLC for metabolic profiling. Metabolite identification was carried out on a LCQ ion trap mass spectrometer. In rat liver slices and in vivo, the major primary metabolite has been identified as 3',5'-dichloro-2,3,4-trihydroxy-2-methylbutyranilide (M5) and was mainly present as glucuronoconjugates. M5 is produced by dihydroxylation of the vinyl group of M2. Other metabolites have been identified as 3-(3,5-dichlorophenyl)-5-methyl-5-(1,2-dihydroxyethyl)-1,3-oxazolidine-2,4-dione (M4), a dihydroxylated metabolite of vinclozolin, which undergoes further conjugation to glucuronic acid, and 2-[[(3,5-dichlorophenyl)-carbamoyl]oxy]-2-methyl-3,4-dihydroxy-butanoic acid (M6), a dihydroxylated metabolite of M1. 相似文献
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476.
Geuns JM Buyse J Vankeirsbilck A Temme EH Compernolle F Toppet S 《Journal of agricultural and food chemistry》2006,54(7):2794-2798
Stevioside (250 mg capsules) was given three times daily to 10 healthy subjects. Steviol glucuronide (steviol 19-O-beta-D-glucopyranosiduronic acid; MM, 494.58; melting point, 198-199 degrees C) was characterized in the 24 h urine as the only excretion product of oral stevioside by MS, NMR, IR, and UV spectroscopy. This is the first report on the unambiguous identification of steviol glucuronide in human urine. 相似文献
477.
López-Galilea I Fournier N Cid C Guichard E 《Journal of agricultural and food chemistry》2006,54(22):8560-8566
Headspace-solid-phase microextraction technique (HS-SPME) coupled with gas chromatography-mass spectrometry (GC-MS) and gas chromatography-olfactometry (GC-O) were used to characterize the aroma compounds of coffee brews from commercial conventional and torrefacto roasted coffee prepared by filter coffeemaker and espresso machine. A total of 47 volatile compounds were identified and quantified. Principal component analysis (PCA) was applied to differentiate coffee brew samples by volatile compounds. Conventional and torrefacto roasted coffee brews were separated successfully by principal component 1 (68.5% of variance), and filter and espresso ones were separated by principal component 2 (19.5% of variance). By GC olfactometry, a total of 34 aroma compounds have been perceived at least in half of the coffee extracts and among them 28 were identified, among which octanal was identified for the first time as a contributor to coffee brew aroma. 相似文献
478.
479.
The role of soil chemical properties,land use and plant diversity for microbial phosphorus in forest and grassland soils
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Elisabeth Sorkau Steffen Boch Runa S. Boeddinghaus Michael Bonkowski Markus Fischer Ellen Kandeler Valentin H. Klaus Till Kleinebecker Sven Marhan Jörg Müller Daniel Prati Ingo Schöning Marion Schrumpf Jan Weinert Yvonne Oelmann 《植物养料与土壤学杂志》2018,181(2):185-197
Management intensity modifies soil properties, e.g., organic carbon (Corg) concentrations and soil pH with potential feedbacks on plant diversity. These changes might influence microbial P concentrations (Pmic) in soil representing an important component of the P cycle. Our objectives were to elucidate whether abiotic and biotic variables controlling Pmic concentrations in soil are the same for forests and grasslands, and to assess the effect of region and management on Pmic concentrations in forest and grassland soils as mediated by the controlling variables. In three regions of Germany, Schwäbische Alb, Hanich‐Dün, and Schorfheide‐Chorin, we studied forest and grassland plots (each n = 150) differing in plant diversity and land‐use intensity. In contrast to controls of microbial biomass carbon (Cmic), Pmic was strongly influenced by soil pH, which in turn affected phosphorus (P) availability and thus microbial P uptake in forest and grassland soils. Furthermore, Pmic concentrations in forest and grassland soils increased with increasing plant diversity. Using structural equation models, we could show that soil Corg is the profound driver of plant diversity effects on Pmic in grasslands. For both forest and grassland, we found regional differences in Pmic attributable to differing environmental conditions (pH, soil moisture). Forest management and tree species showed no effect on Pmic due to a lack of effects on controlling variables (e.g., Corg). We also did not find management effects in grassland soils which might be caused by either compensation of differently directed effects across sites or by legacy effects of former fertilization constraining the relevance of actual practices. We conclude that variables controlling Pmic or Cmic in soil differ in part and that regional differences in controlling variables are more important for Pmic in soil than those induced by management. 相似文献
480.
Elisabeth S. Simelton Delia C. Catacutan Thu C. Dao Bac V. Dam Thinh D. Le 《Agroforestry Systems》2017,91(1):51-67
Agroforestry is known to have multiple economic and environmental benefits. Despite this, the adoption of agroforestry in Viet Nam is limited both in extent and diversity of components and practices. Our study identified gaps for agroforestry adoption in current policies and policy implementation. National policy and provincial instructions and decisions were reviewed and discussed during ten stakeholders’ consultation workshops. The review and workshops concluded that there were no specific national and few provincial specific policies promoting agroforestry. In addition, the segregation of policies into agriculture and forestry, promoted monoculture practices and discouraged the integration of mixed annual and perennial tree species. Completing the forestland allocation process was considered essential for long-term investment on land and providing collateral for loans. More holistic policies, such as a provincial strategy for agroforestry development that would enable flexible integration of agriculture, forestry and livestock were perceived to be more effective and inclusive to poor and non-poor farmers. Specific cross-cutting budget allocation would be necessary for capacity building, upscaling agroforestry models, procurement of high-quality inputs, and establishing post-harvest processing and marketing investments. 相似文献