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91.
Bobbert MF Santamaría S van Weeren PR Back W Barneveld A 《Veterinary journal (London, England : 1997)》2005,170(2):212-221
The purpose of this study was to quantify performance characteristics of good jumping horses, and to determine whether these were already detectable at foal age. Kinematic data were collected of horses performing free jumps over a 0.60 m high fence at six months of age and of these same horses jumping with a rider over a 1.15 m high fence at five years of age. At five years of age the horses were divided into three groups on the basis of a puissance competition: a group of seven best jumpers that made no errors and in the end cleared a 1.50 m high fence, a group of nine worst jumpers that were unable to clear a 1.40 m high fence, and an intermediate group of 13 horses. Longitudinal kinematic data was available for all seven best jumpers and for six of the nine worst jumpers. Average values of variables for the best jumpers were compared with those of the worst jumpers for the jumps over 1.15 m. In the group of best jumpers, the forelimbs were shorter at forelimb clearance due to increased elbow flexion, and the hind limbs were further retroflexed at hind limb clearance. The same superior technique in clearing fences with the limbs was also found in this group at six months of age. Nevertheless, for individual horses it turned out to be too far-fetched to predict adult jumping capacity on the basis of kinematic variables collected during submaximal jumps at foal age. 相似文献
92.
Biochemical and physiological characteristics of salt-tolerant (88 mM, 264 mM and 440 mM NaCl) strains of Bradyrhizobium were evaluated according to their capacity for using different carbon sources, growth rate, resistance to antibiotics, plasmid
profile and exopolysaccharide production. Salt-tolerant strains significantly enhance their capacity to oxidize C sources
(about 75–85 compounds) by increasing growth rate and exopolysaccharide production involved in adhesion, resulting in a greater
adapting capacity to colonize unfavorable saline environments. However, salt stress could work as a curing agent and thus
the gene stability would become critical for the biological nitrogen-fixation information present in plasmids, as is the case
in Rhizobium.
Received: 5 January 1998 相似文献
93.
F. Laos Patricia Satti Ingrid Walter María Julia Mazzarino Susana Moyano 《Biology and Fertility of Soils》2000,31(6):462-469
The main objectives of this study were to determine: (1) the agronomic value of composted and noncomposted residues originated
in the Andean-Patagonian region (APR), and (2) whether aerobic incubations provide a reliable index of nutrient availability
to estimate application rates. A Xeric Mollisol of the transitional zone between the APR and the Patagonian steppe, amended
with composted and noncomposted residues, was employed in laboratory incubations without plants and in a 5-month greenhouse
trial with ryegrass. Noncomposted residues were biosolids and fish wastes (FW) collected under farming cages. Composts were
obtained from fish offal and biosolids mixed with sawdust, woodshavings and yard trimmings. A commercial compost was also
included. In laboratory incubations at similar rates of application (10 g kg–1), net N mineralization (Nmin) was about two-fold higher with the noncomposted (17–23%) than with the composted residues (0–12%) and P release was very
high with the FW. Ryegrass yields were closely related to the total Kjeldahl N and mineralized N of the organic residues and
weakly related to their P contents (total or extractable). Yields were increased even in the case of composts which exhibited
very low values of Nmin (and slight N immobilization) during laboratory incubation, suggesting that the presence of plants enhanced Nmin at rates of 10–20 g kg–1. Soil residual extractable P after ryegrass removal was high for fish-derived amendments and the commercial product, suggesting
a potential risk of P pollution when these are applied according to N requirements. Aerobic incubations provided a relatively
good index with which to assess adequate rates of application.
Received: 17 July 1999 相似文献
94.
Spatial and temporal variability of physical properties of Aquands under different land uses in southern Chile 下载免费PDF全文
José Dörner Dorota Dec Oscar Thiers Leandro Paulino Felipe Zúñiga Susana Valle Oscar Martínez Rainer Horn 《Soil Use and Management》2016,32(3):411-421
The aquands found in southern Chile are derived from volcanic ash and contain high levels of organic matter. Due to the presence of an impermeable stratum, they have shallow soil profiles, which induce waterlogging for several months each year. These fragile soils, locally known as ‘Ñadi’, cover an area of 475 000 hectares and have undergone intensive land use changes, which have affected the soil physical properties. These are still not well understood but are relevant for the design of efficient drainage systems. The aim of this research was to analyse the impact of the land use change in Ñadi soils on the spatial and temporal variability of their soil physical properties. For the land use change from secondary native forest (sNF) to naturalized grassland (NG), the effective soil depth was measured at defined points. Time‐ and space‐dependent changes of water‐table depth and penetration resistance were recorded. Volumetric water content and soil temperature were measured with sensors installed at three depths and the water retention curve and air permeability at these depths were also determined. The changes in land use over time have induced a reduction in soil depth. Soils under NG showed a smaller soil water storage capacity, air capacity and permeability compared with soils under sNF, as well as waterlogging during winter and greater mechanical strength and soil profile temperatures during summer. Therefore, the land use change affected the spatial and temporal variability of soil physical functions across the field. 相似文献
95.
96.
Cohen-Cory S 《Science (New York, N.Y.)》2002,298(5594):770-776
Synapse formation and stabilization in the vertebrate central nervous system is a dynamic process, requiring bi-directional communication between pre- and postsynaptic partners. Numerous mechanisms coordinate where and when synapses are made in the developing brain. This review discusses cellular and activity-dependent mechanisms that control the development of synaptic connectivity. 相似文献
97.
Sancho JV Pozo OJ Zamora T Grimalt S Hernández F 《Journal of agricultural and food chemistry》2003,51(15):4202-4206
A rapid and sensitive liquid chromatography/electrospray ionization/tandem mass spectrometry (LC-ESI-MS-MS) method has been developed for the determination of the plant growth regulator paclobutrazol in pear samples. Extraction was performed with methanol by using a high-speed blender Ultra-Turrax, and 10 microL of pear extract was directly injected in the LC-ESI-MS-MS system without any previous sample treatment. The highest sensitivity of the method was achieved under MS-MS conditions obtaining a limit of detection of 0.7 microg/kg and a quantification limit of 5 microg/kg, with a run time of only 5.5 min. Recoveries for paclobutrazol from spiked pear samples at 0.005, 0.05, and 0.5 mg/kg were around 82-102% with relative standard deviations between 2 and 7%. The method was applied to real treated and untreated samples of pears, using quality control samples as a evaluation of the method reliability. Two MS-MS transitions were selected, one for quantification (294 > 70) and the other for confirmation of the analyte (296 > 70). All the experiments were performed in compliance with good laboratory practices. 相似文献
98.
Fernández-Cruz ML Villarroya M Llanos S Alonso-Prados JL García-Baudín JM 《Journal of agricultural and food chemistry》2004,52(4):860-863
Field trials have been carried out to determine the variability of residue levels of fenitrothion and its main metabolites fenitrothion-oxon and 3-methyl-4-nitrophenol in individual kaki fruits versus composite samples, in peel versus flesh, and in whole uncooked versus whole cooked fruits. Residue levels have been determined by gas chromatography with thermionic specific detection after extraction with ethyl acetate and without further cleanup. At harvest, residue levels of fenitrothion were below maximum residue levels (MRLs) and the two metabolites 3-methyl-4-nitrophenol and fenitrothion-oxon could be quantified with average amounts of 0.080 and 0.012 mg/kg, respectively. Levels of fenitrothion decreased 88% after peeling, whereas temperature did not result in a high variation. The ratios of the highest residue level in the individual fruits to the corresponding mean of residue levels in the composite samples for fenitrothion were <3. This value is lower than that recommended by the World Health Organization as default value for consumer risk assessment. 相似文献
99.
Svetaz L Tapia A López SN Furlán RL Petenatti E Pioli R Schmeda-Hirschmann G Zacchino SA 《Journal of agricultural and food chemistry》2004,52(11):3297-3300
The crude methanolic extract of Zuccagnia punctata was active toward the fungal pathogens of soybean Phomopsis longicolla and Colletotrichum truncatum. Assay guided fractionation led to the isolation of two chalcones, one flavanone and a new caffeoyl ester derivative as the compounds responsible for the antifungal activity. Another new caffeoyl ester derivative was isolated from the antifungal chloroform extract but proved to be inactive against the soybean infecting fungi up to 50 microg/mL 相似文献
100.
Assessment of the volatile composition of juices of apricot, peach, and pear according to two pectolytic treatments 总被引:1,自引:0,他引:1
Riu-Aumatell M López-Tamames E Buxaderas S 《Journal of agricultural and food chemistry》2005,53(20):7837-7843
The behavior of volatile compounds according to two enzymatic treatments applied during the manufacture of fruit juice is described. More than 80 compounds were detected of a wide range of chemical families (alcohols, aldehydes, ketones, terpenoids, esters, norisoprenoids, ...). Theaspirane and alpha-isophoron were tentatively identified for the first time in apricot and peach fruits. The enzymes used, for extraction or clarification of fruit juices, modified the polysaccharides separated by molecular weight and the content of soluble polysaccharides. This could indicate differences in the fruit juice matrix, which could be related to observed changes in the volatile profile. In apricot, the enzymes enhanced the juice in terpenes and norisoprenoids as varietal compounds. In peach and pear, the enzymes used did not favor the amount of lactones and decadienoate esters, the character impact compounds, respectively. 相似文献