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101.
Patel HA Singh H Havea P Considine T Creamer LK 《Journal of agricultural and food chemistry》2005,53(24):9590-9601
Whey protein concentrate solutions (12% w/v, pH 6.65 +/- 0.05) were pressure treated at 800 MPa for 20-120 min and then examined using size exclusion chromatography (SEC), small deformation rheology, transmission electron microscopy, and various types of one-dimensional (1D) and two-dimensional (2D) polyacrylamide gel electrophoresis (PAGE). The pressure-treated samples showed a time-dependent loss of native whey proteins by SEC and 1D PAGE and a corresponding increase in non-native proteins and protein aggregates of different sizes. These aggregates altered the viscosity and opacity of the samples and were shown to be cross-linked by intermolecular disulfide bonds and by noncovalent interactions using 1D PAGE [alkaline (or native), sodium dodecyl sulfate (SDS), and SDS of reduced samples (SDS(R))] and 2D PAGE (native:SDS and SDS:SDS(R)). The sensitivity of the major whey proteins to pressure was in the order beta-lactoglobulin B (beta-LG B) > beta-LG A > bovine serum albumin (BSA) > alpha-lactalbumin (alpha-LA), and the large internal hydrophobic cavity of beta-LG may have been partially responsible for its sensitivity to high-pressure treatments. It seemed likely that, at 800 MPa, the formation of a beta-LG disulfide-bonded network preceded the formation of disulfide bonds between alpha-LA or BSA and beta-LG to form multiprotein aggregates, possibly because the disulfide bonds of alpha-LA and BSA are less exposed than those of beta-LG either during or after pressure treatment. It may be possible that intermolecular disulfide bond formation occurred at high pressure and that hydrophobic association became important after the high-pressure treatment. 相似文献
102.
Llauradó JM Rozès N Constantí M Mas A 《Journal of agricultural and food chemistry》2005,53(4):1003-1011
Low-temperature fermentations (13 degrees C) are considered to improve wine aromatic profiles. However, because the risk of stuck and sluggish fermentations is high, these fermentations are not common. The aim of this paper was to analyze the effect of different preadaptation protocols in two commercial wine strains on the fermentation and some wine parameters. Preadaptation is understood to be the process between the rehydration of active dry yeast and the inoculation. In this study, it consisted of preparing a fermentation starter (addition of yeast grown at 25 degrees C) or inocula preadapted at low temperatures (as before, but grown at a fermentation temperature of 13 or 17 degrees C). These results were compared with those of rehydrated active dry yeast, and a commercial "cryotolerant" yeast was used as a reference. General fermentation kinetic parameters, yeast imposition, nitrogen consumption, and main wine products were analyzed. The results showed that the preadaptation of a yeast could improve the fermentation performance, although this improvement was strain-dependent. Low-temperature fermentations also had some general effects: reduction of acetic acid and fusel alcohol production and increased concentrations of glycerol. When the yeast performed better in fermentation because of preadaptation, nitrogen consumption was faster and the wine's "negative" attributes (acetic acid, fusel alcohols) were significantly reduced. Thus, in some strains, preadaptation could be an effective mechanism for improving low-temperature fermentation, which also significantly reduces detrimental wine attributes. 相似文献
103.
Rondini L Peyrat-Maillard MN Marsset-Baglieri A Berset C 《Journal of agricultural and food chemistry》2002,50(10):3037-3041
The bioavailability of ferulic acid (FA; 3-methoxy-4-hydroxycinnamic acid) and its metabolites was investigated in rat plasma and urine after an oral short-term ingestion of 5.15 mg/kg of FA. Free FA, glucuronoconjugates, and sulfoconjugates were quickly detected in plasma with a peak of concentration found 30 min after ingestion. Sulfoconjugates were the main derivates ( approximately 50%). In urine, the cumulative excretion of total metabolites reached a plateau 1.5 h after ingestion, and approximately 40% were excreted by this way. Free FA recovered in urine represented only 4.9 +/-1.5% of the native FA consumed by rats. Glucuronoconjugates and sulfoconjugates represented 0.5 +/- 0.3 and 32.7 +/- 7.3%, respectively. These results suggested that a part of FA incorporated in the diet was quickly absorbed and largely metabolized in sulfoconjugates before excretion in urine. 相似文献
104.
Villiere A Viau M Bronnec I Moreau N Genot C 《Journal of agricultural and food chemistry》2005,53(5):1514-1520
Proteins often stabilize food emulsions and are also able to promote or delay lipid oxidation in complex systems. The purpose of this work was to investigate the relationship between metal ion availability and oxidative stability of oil-in-water emulsions stabilized by bovine serum albumin (BSA) or sodium caseinate (NaCas). Emulsions with similar and stable droplet size distributions were prepared with stripped sunflower oil (30 vol %) and protein solutions (20 g L(-)(1); pH = 6.5). In the absence of the water-soluble metal chelator EDTA, oxygen uptake, conjugated dienes, and volatile compounds developed faster in NaCas-stabilized emulsions than in those prepared with BSA. This effect is attributed to the chelating properties of NaCas and to electrostatic interactions that attract some metal ions at the interface where they could initiate lipid oxidation. When EDTA (100 muM) was present, oxidation was delayed to a greater extent in emulsions made with NaCas than in BSA stabilized emulsions. These conditions probably enabled NaCas to exert free-radical-scavenging activity. 相似文献
105.
A saprolite derived from a gneiss has been sampled in a fault zone at Charlesbourg, near Quebec city. The weathering largely exceeding 6 m in depth and a till overburden suggest preglacial alteration under warmer climatic conditions. This is further supported by the presence of high (up to 15% ) percentages of crystalline iron oxides (goethite and lepidocrocite). Four different facies were defined in the saprolite. Mineralogical analyses were performed on the clay fractions and the following associations were found: swelling minerals + kaolinite, kaolinite, kaolinite + gibbsite, swelling minerals + kaolinite.The degree of weathering of 2:1 minerals into kaolinite seemed to be related to internal drainage conditions. Cation exchange capacity of the saprolite was adequately explained by the clay and silt fraction contributions. 相似文献
106.
Adansonia digitata (baobab tree), a multipurpose tree species, occurs throughout semi-arid and arid zones of Africa. Its survival is, however,
threatened by bush fire, over-exploitation, grazing and a lack of natural regeneration. The extent of variation in fruit characteristics,
seed germination and seedling traits of the baobab tree in Benin, was evaluated at climatic zone level. 1,200 fruits were
sampled in each of the three climatic zones of Benin for morphological assessment and to assess germination rate and seedling
growth dynamics according to the climatic zones, the used substrate and the scarification of the seed coat. There were significant
differences in fruit characteristics not only between climatic zones but also between individuals from the same zone and within-trees.
Using mechanical scarification on freshly-collected baobab seeds negatively affected the germination rate of baobab seeds
sampled in the Guinean and Sudano-Guinean zones of Benin. The best-germination rate was recorded for non-treated seeds from
the Guinean zone, up to 57% on day 25. All seeds germinated best on the sand substrate, but supplying organic matter promoted
further seedling growth after 11 days of germination. Based on these observations we propose some strategies for efficient
ex situ conservation of baobab in Benin. 相似文献
107.
Riparian forests are classified as endangered ecosystems in general,particularly in sahelian countries like Burkina Faso because of human-induced alterations and civil engineering works.The modification of this important habitat is continuing,with little attention being paid to the ecological or human consequences of these changes.The objective of this study is to describe the variation of woody species diversity and dynamic in riparian forests on different type of watercourse banks along phytogeographical gradient in Burkina Faso.All woody species were systematically measured in 90 sample plots with sides of 50 m × 20 m.Density,dominance,frequency and species and family importance values were computed to characterize the species composition.Different diver-sity indices were calculated to examine the heterogeneity of riparian forests.A total of 196 species representing 139 genera and 51 families were recorded in the overall riparian forests.The species richness of individuals with dbh ≥ 5cm increased significantly from the North to the South along the phytogeographical gradient and varied significantly between the different types of riparian forests.Similarity in tree species composition between riparian forests was low,which indicates high beta diversity and reflects differences in habitat conditions and topography.The structural characteristics varied significantly along the phyto-geographical gradient and between the different types of riparian forests.The diameter class distribution of trees in all riparian forests showed a reverse "J" shaped curve except riparian forest of stream indicating vegetation dominated by juvenile individuals.Considering the ecological importance of riparian forest,there is a need to delineate and classify them along watercourses throughout the country. 相似文献
108.
Augustin K.N. Aoudji Anselme Adégbidi Jean C. Ganglo Valentin Agbo Armand S.I. Yêvidé Charles De Cannière Philippe Lebailly 《Forest Policy and Economics》2011,13(8):642-651
The study used the expectancy-disconfirmation framework to investigate the satisfaction among urban consumers of teak pole in South Benin, so as to identify the areas where interventions are needed to secure market opportunity for smallholder forestry. A survey was conducted in five cities; and 223 household-heads were interviewed using systematic sampling, with a random start. Data were collected on socio-demographic characteristics, teak pole consumption forms, behaviour patterns, and motivations. Respondents also rated their expectations and perceptions for a set of nine attributes on a 7 points Likert scale. Hierarchical ascending cluster analysis was performed to identify consumer segments; and satisfaction level was analysed per segment, by determining the gap between expectations and perceptions, for all attributes. Four consumer segments were identified; and sociodemographic profiles differed across those segments. Competitive price was an important purchasing motivation across the identified segments. Consumers were dissatisfied with price, availability, knot frequency, bending, length, hardness, and durability of teak pole. The efforts to meet the consumer expectations should be concentrated on building farmers' capacity in silvicultural management, and ensuring the availability of good planting material. The issue of competitive price might be addressed, through the improvement of the overall efficiency in the value chain. 相似文献
109.
Mathieu Le Meur Emmanuelle Montargès-Pelletier Allan Bauer Renaud Gley Sylvie Migot Odile Barres Claire Delus Frédéric Villiéras 《Journal of Soils and Sediments》2016,16(5):1625-1642
Purpose
Suspended particulate matter (SPM) plays an important role in the transport and fate of contaminants in the environment. To better understand the relationships between contaminants and SPM, SPM properties, and their variations with flow regime, river size, land use, and season should be considered.Materials and methods
The grain size distribution, elemental composition, and mineralogy of SPM from different stations along the Moselle River (Lorraine, France) were investigated at the particle scale during different flow regimes. The resulting data were compared with the elemental composition of the dissolved compartment to understand the role of particles in element transport.Results and discussion
The grain size distribution, elemental composition, and mineralogy of SPM along the Moselle River and during different flow regimes showed only slight variations, except for the Fensch and Orne tributaries, two rivers that were impacted by inherited steel-making industrialization and different land use. In the Moselle River, SPM mainly consisted of clay minerals, while in Fensch and Orne Rivers, SPM mainly consisted of multiple types of anthropogenic particles. The diffuse urbanization gradient was hardly recognized based on the Trace Metal Element (TMEs) content in the river SPM, while the rivers impacted by the steel industries had greater TME contents. Finally, the TME content in the Moselle SPM was more strongly influenced by water flow than by the position of sampling on the linear reach of the Moselle River. The partitioning of TMEs in the particles and water at the main Moselle station (Frouard) revealed that SPM predominantly contributed to TMEs transport.Conclusions
This study confirmed that catchment geology greatly contributed to the SPM composition in the mean-sized rivers. In addition, the high anthropogenic pressure could be deciphered for small tributaries. Furthermore, this study allowed us to observe the high contribution of particles to TMEs and Rare Earth Element (REEs) transportation.110.
In search of a maize ideotype for cell wall enzymatic degradability using histological and biochemical lignin characterization 总被引:1,自引:0,他引:1
Méchin V Argillier O Rocher F Hébert Y Mila I Pollet B Barriére Y Lapierre C 《Journal of agricultural and food chemistry》2005,53(15):5872-5881
Grass cell wall degradability is conventionally related to the lignin content and to the ferulic-mediated cross-linking of lignins to polysaccharides. To better understand the variations in degradability, 22 maize inbred lines were subjected to image analyses of Fasga- and M?ule-stained stem sections and to chemical analyses of lignins and p-hydroxycinnamic acids. For the first time, the nearness of biochemical and histological estimates of lignin levels was established. Combination of histological and biochemical traits could explain 89% of the variations for cell wall degradability and define a maize ideotype for cell wall degradability. In addition to a reduced lignin level, such an ideotype would contain lignins richer in syringyl than in guaiacyl units and preferentially localized in the cortical region rather than in the pith. Such enrichment in syringyl units would favor wall degradability in grasses, contrary to dicots, and could be related to the fact that grass syringyl units are noticeably p-coumaroylated. This might affect the interaction capabilities of lignins and polysaccharides. 相似文献