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191.
We developed a basal area growth model for recovery of advance growth of Norway spruce trees after clear-cutting. Stem diameter growth at ground level and needle-mass characteristics were measured on permanent sample plots in Estonia. Both tree ring analysis (destructive sampling on one sample plot) and yearly repeated measurement data (two plots) were used to quantify advance growth. Basal area growth of small trees was estimated by multiple regression analysis. Previous-year basal area of the tree and basal area growth explained tree performance the next year. Tree needle-mass variables characterizing the acclimation status of the tree were included in the model as explanatory factors. Needle samples (one shoot from the upper third of each tree crown) were collected each year after the growth period from all sample trees. Needle masses of shoots from consecutive years were correlated and this variable was used as a predictor in the simulation model. Accelerating growth was observed in trees that exceeded the growth threshold in the year after release: the greater the needle mass per shoot, the greater the acceleration in growth. Competition among advance regeneration trees was included in the model: small trees under taller neighbors exhibited reduced growth. We found that trees released from a long period of heavy shade can survive, but the time needed for acclimation and resumption of competitive growth rates is considerably longer than for trees released from light shade. Such trees can be used for forest regeneration, but competition control (particularly reducing the proportion of fast-growing hardwoods) is required.  相似文献   
192.
The aim of this study was to evaluate the effect of the level of fat and selected fatty acids found in the milk of sows on the rearing of native breed piglets. Simultaneously, in order to improve the accuracy of the performed analyses, atomic absorption spectrometry was employed in the applied analytic methodology. The experimental animal material comprised 60 sows of the indigenous White Z?otnicka breed. Colostrum and milk were collected on the first and 14th days of lactation. In all, 240 samples were collected. The following parameters were determined in the course of the experiment: number and weight of piglets, body weight gains as well as deaths of piglets. A total of 1270 born piglets was subjected to investigations. The performed experiments demonstrated that, with the progress of the lactation period, the content of fat and saturated fatty acids (SFA) turned out to be statistically significant and showed a growing tendency. Fat increased by about 2% and palmitic acid (C16:0) increased most, that is by 5%. Linolic (C18:2) and linolenic (C18:3) acids revealed decreasing trends. Irrespective of the day of lactation, the level of unsaturated fatty acids (UFA) determined in sows' colostrum and milk was higher in comparison with that of SFA, and the UFA to SFA ratio ranged from 1.84% to 1.33%. Proportions of n‐6 to n‐3 fatty acids were determined at the level of about 1.6:1.0 in the colostrum and 1.3:10 in milk. The highest daily body weight gains were recorded in the case of piglets derived from sows with the highest fat level – 294 g, while in the case of stearic acid (C18:0), the smaller its concentration in the colostrum and milk of the experimental sows, the better body weight gains of piglets – 262 g. At the same time, stearic acid (C18:0) was found to exert a statistically significant effect on piglet mortality at the level of P ≤ 0.05. Its highest concentration caused the highest proportion of deaths among piglets ‐ 16.23%. The performed analysis of correlations that occurred between fat, fatty acids and traits associated with piglet rearing confirmed that linolic acid (C18:2; n‐6) was highly significantly correlated with piglets' body weights (r = 0.456**) and was negatively correlated with piglets' deaths (r = ?0.312). On the other hand, fat revealed correlation with body weight gains of piglets (r = 0.333*_ and a negative correlation with deaths of piglets (r = ?0344*). Recapitulating, the results of the performed experiments revealed that differences in the levels of fat and fatty acids found in sows' colostrum and milk influenced results of piglet rearing. Together with the increase in the content of fat and UFA in sows' colostrum and milk, piglets were characterized by the best body weight, growth rate, as well as by small mortality.  相似文献   
193.
194.
The aim of this work was to evaluate the antioxidant potential of teas prepared from twenty-four commercially available berries and flowers of Sambucus nigra L. in relation to their phenolic profile, as reflected by the most representative phenolic acids (caffeic, chlorogenic, p-coumaric, ferulic, gallic and syringic acids); flavonols (quercetin, kaempferol, myricetin and rutin); and total phenolic (TPC), phenolic acid (TAC) and flavonoid (TFC) contents. The infusions prepared from elderflowers contained more abundant phenolic compounds than the elderberry infusions. The TPC of these infusions ranged from 19.81 to 23.90 mg of gallic acid equivalents/g dry weight of sample (GAE/g DW) for elderberries and from 15.23 to 35.57 mg GAE/g DW for elderflowers, whereas the TFC ranged from 2.60 to 4.49 mg of rutin equivalents/g dry weight of sample (RUTE/g DW) in elderberry infusions and from 5.27 to 13.19 mg RUTE/g DW in elderflower infusions. Among the phenolic compounds quantified in this study, quercetin (2.07–9.48 mg/g DW) and myricetin (1.17–9.62 mg/g DW) had the highest concentrations in the teas prepared from berries and flowers, respectively. Moreover, the antioxidant potential of elder infusions assessed by 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical and ferric reducing antioxidant power (FRAP) assays revealed that the teas prepared from flowers had higher mean DPPH and FRAP activities than the teas prepared from berries. Therefore, elder beverages could be important dietary sources of natural antioxidants that contribute to the prevention of diseases caused by oxidative stress.  相似文献   
195.
LC/MS analysis of cyclohexanedione oxime herbicides in water   总被引:1,自引:0,他引:1  
A multiresidue method for the determination of alloxydim (methyl 2, 2-dimethyl-4, 6-dioxo-5-[1-[2-propenyloxy)amino]butylidene]cyclohexanec arb oxylate), clethodim (E, E)-(+/-)-2-[1-[[3-chloro-2-propenyl)oxy]imino]propyl]-5-[2-(ethylthio )propyl]-3-hydroxy-2-cyclohexen-1-one), sethoxydim ((+/-)-2-[1-(ethoxyimino)butyl]-5-[2-ethylthio)propyl]-3-hydroxy-2 -cy clohexen-1-one), and two metabolites, clethodim sulfoxide ((E, E)-(+/-)-2-[1-[[3-chloro-2-propenyl)oxy]imino]propyl]-5-[2-(ethylsulf inyl)propyl]-3-hydroxy-2-cyclohexen-1-one) and sethoxydim sulfoxide ((+/-)-2-[1-(ethoxyimino)butyl]-5-[2-ethylsulfinyl)propyl]-3 -hydroxy- 2-cyclohexen-1-one), in water by high-performance liquid chromatography/electrospray/mass spectrometry (LC/ES/MS) is reported. River water and distilled water were spiked at 0.08 and 0.8 microgram L(-1) with all three herbicides, which were then extracted from the water by C(18)-SPE (SPE = solid-phase extraction). The herbicides and metabolites were quantified and confirmed using selected ion monitoring. The percent recoveries of the herbicides from water spiked at 0.8 microgram L(-1) were as follows: alloxydim, 117 +/- 11%; clethodim, 96 +/- 14%; sethoxydim, 89 +/- 13%. There was no evidence of oxidation of clethodim and sethoxydim during the extraction to their respective sulfoxides. The limit of quantitation was <0.1 microgram L(-1). We have shown that we can analyze and confirm three cyclohexanedione oxime herbicides and two metabolites in water by LC/ES/MS. This multiresidue method should also be appropriate for other cyclohexanedione oximes.  相似文献   
196.
The effect of arable field margin composition on invertebrate biodiversity   总被引:1,自引:0,他引:1  
A replicated field experiment designed to compare five types of field margin in terms of their invertebrate biodiversity was established in North Yorkshire, UK. Four replicate margins on arable land each contained five treatment plots 72 m long by 6 m wide. The treatments were: (1) cropped to the edge; (2) sown ‘tussocky’ grass mix; (3) sown ‘grass and wildflower’ mix; (4) Split margin (3 m ‘tussocky’ grass adjacent to hedge and 3 m ‘grass and wildflower’ next to crop); and (5) natural regeneration. Invertebrates were sampled by pitfall trapping, sweep netting, and butterfly and bumblebee transects, and identified to species level. The use of different flower species by foraging bumblebees was also examined.Despite all treatments containing a flush of annual weeds early in the establishment year, the five margin types were distinct in their vegetation composition by their first mid-summer. Where statistically significant results were obtained for invertebrates, avoidance of the ‘cropped’ treatment was by far the commonest observed response. This tendency could be clearly demonstrated amongst the carabids, spiders, butterflies, bumblebees, millipedes and harvestmen, with margins often containing double or more the number of invertebrates of similar areas cropped to the edge. Having avoided the crop, preferences for other margin types were mixed, but there was a marked tendency by many nectar and/or pollen-feeding, flying insects towards greater abundance on those margins containing sown ‘wildflowers’ (e.g. butterflies Meadow Brown and Ringlet, Bumblebees, Pollen Beetle Meligethes sp.) or flowers either sown or unsown (Soldier Beetle Rhagonycha fulva). There was a less strong tendency for predatory species occurring in the vegetation canopy and depending on small, especially flying insects for food, to also prefer the flowery treatments (e.g. total spiders caught by sweeping, seven-spot ladybird). Harvestmen in autumn reject natural regeneration in favour of any sown treatment. Only one species, the carabid Nebria brevicollis, was trapped in higher numbers in the cropped treatment than on any sown margin, and then only in autumn. Of the six common bumblebee species, the two longest-tongued species showed different patterns of flower visitation from the remaining four.These results clearly demonstrate that sown field margins can rapidly produce substantial biodiversity benefits on arable land, with the resulting fauna influenced by the type of field margin created.  相似文献   
197.
Deficit irrigation (DI) is an effective way to save irrigation water while maintaining sustainable yield in irrigated crops. However, limited information is available related to canopy structure and solar radiation use under DI condition. In this study, our objective was to assess maize hybrids for leaf development, photosynthetically active radiation (PAR) interception and water use under DI condition. Field experiments were conducted in 2016 and 2017 in four maize hybrids at well-watered (I100, referring to 100% evapotranspiration [ET] requirement) and DI (I75, referring to 75% ET requirement) water regimes. Compared to I100, I75 did not reduce maize biomass and grain yield. Although DI reduced the leaf appearance rates (1.5% in 2016 and 7.6% in 2017) and resulted in greater variations in leaf area index (LAI) among hybrids, the amount of PAR interception was not affected during the growing season. DI significantly reduced the seasonal ET in both years (19.8% in 2016 and 26.6% in 2017). All the hybrids extracted more soil water (29 mm in 2016 and 27 mm in 2017) at I75 than at I100. Maize plants at I75 had greater water use efficiency (WUE) (1.68 kg m−3) than those at I100 (1.41 kg m−3). However, DI did not affect radiation use efficiency (RUE). In conclusion, DI at I75 maintained grain yield through improved soil water extraction and WUE but stable canopy radiation interception and RUE.  相似文献   
198.
199.
Seventy samples of bone bioptates from 70 cows were examined by the biochemical analysis and radiographically. By biochemical examination of bone bioptates taken from the tuber coxae we demonstrated the osteoporotic process in 87% of examined dairy cows, the osteomalacic process in 57% and the combined form, i.e. osteoporosis/osteomalacia in 51.4% of examined dairy cows. According to the distribution of findings in relation to the phases of reproduction cycle, the frequency of pathological findings was found to be highest in cows after calving. The examination of ash for the content of osteotrophic minerals, calcium and phosphorus, has demonstrated the physiological relation in 5.7% of dairy cows only, widened ratio in 87.2% and reduced one in 7.1% of dairy cows. By a comparison of the biochemical finding with the radiographic one we have revealed the difference, by 23% lower, in identification of pathological cases by the radiographic method. The method of radiographic examination of bone bioptates can be used as screening in the diagnostics of metabolic osteopathies.  相似文献   
200.
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