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31.
Phenolic compounds were extracted from defatted flaxseeds using ethanol-dioxane (1:1, v/v). The crude extract obtained was purified using Amberlite XAD-16 column chromatography with water and methanol as mobile phases. RP-HPLC and SE-HPLC showed a lignan macromolecule (LM) as a dominant phenolic compound in the purified extract. After the alkaline hydrolysis of LM caffeic acid glucoside (CaAG) was isolated using a semi-preparative HPLC and its structure was confirmed by LC-ESI-MS. In LM of the investigated flaxseed, one molecule of caffeic acid corresponded with five molecules of p-coumaric acid and two molecules of ferulic acid. The presence of caffeic acid in the lignan molecule might be very beneficial due to its high antioxidant activity.  相似文献   
32.
In the study the effects of artificial reproduction of sterlet (Acipenser ruthenus) fed different feed ration were compared. Three doses of feed were used: 1.0%, 0.75% and 0.5% of the fish biomass per day. The results indicate that the feed rations for fish used for caviar production or breeding material should differ. The optimal ration for the quality of sex products and progeny was 0.75% of the fish biomass, whereas in view of the number of maturing fish, the better ration was that of 1% of the fish biomass. In group fed 0.75% of the fish biomass per day the highest GSI value, the largest eggs and hatch and the highest survival to the hatch were noted. The feed ration of 0.5% of the fish biomass was too low, as indicated by the low parameters of eggs obtained, their survival and the smallest number of mature and ovulating females. These results can provide direction for the creation and exploitation of spawner stocks as well as for other sturgeon species cultured under controlled conditions.  相似文献   
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Weeds are a primary factor limiting maize yield. Their occurrence and abundance are affected considerably by environmental factors and farming practices. The variability of weed number in maize depending on the soil type and farm size was investigated. Farms of different sizes vary in farming practices, which affects weediness. Based on this assumption, farm size was considered as indirect factor affecting weed abundance. An investigation of 45 farms that differed in size (5–15 ha, 15–50 ha, >50 ha) and soil type (chernozem, distric cambisol, haplic luvisol) was conducted. Thirteen dominant weed species persistently occurring in maize fields in south-western Poland were examined. Regardless of the soil type and farm size, the most abundant weed species were Echinochloa crus-galli and Chenopodium album. In addition to these species, the most numerous weeds on chernozems were Setaria viridis and Solanum nigrum, while on haplic luvisols and distric cambisols, the most numerous were Viola arvensis and Elymus repens. Additionally, on haplic luvisols, Anthemis arvensis was abundant. Small farms were stronger infested by weeds than large farms due to the implementation of extensive weed-supressing practices, especially low herbicide use. Soil type affected the number of weeds to a greater extent than did farm size.  相似文献   
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Human exploitation of wild‐living animals has been suggested to create a ‘landscape of fear’. A consequence could be that individuals surviving intensive harvesting, either as a result of behavioural plasticity and/or evolutionary change, exhibit increased average timidity. In the aquatic world, such effects are particularly well documented in passively operated fishing gears common to many commercial and recreational fisheries, such as angling, trapping or gill netting. We thus propose that an exploitation‐induced timidity syndrome should be a widespread pattern in fisheries. Importantly, we argue that the syndrome can be associated with several ecological and managerial consequences for social groups, populations, food webs, fisheries and assessment of stocks. We suggest research priorities to deepen our understanding of how exploited fish populations behaviourally respond to harvesting.  相似文献   
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Mineralogical and chemical analyses of the ashfall from Mount St. Helens on 18 May 1980 indicate that there were two distinct ashes. The early dark ash is composed principally of plagioclase and lithic fragments of plagioclase and glass with titanium-rich magnetite and some basaltic hornblende and orthopyroxene. The later pale ash, four-fifths by weight of the whole fallout, is 80 percent glass with plagioclase as the principal crystalline phase. Quartz and potassium feldspar are rare to absent in both ashes. Chemical analyses of nine ash fractions and of the glass in each type emphasize the differences between the two ash types and their chemical homogeneity.  相似文献   
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The shrinkage of the peat soils that accompanies the soil moisture changes is an important feature of such soils and has strong influence on their physical attributes and soil water management. The relationships between soil moisture and volume are often described using shrinkage characteristic curves by relating void ratio (volume of voids per unit volume of solids) to moisture ratio (volume of water per volume of solids). For conversion of soil volume changes into cracks volume and subsidence, a dimensionless shrinkage geometry factor is used. The paper presents results of volumetric shrinkage behavior and the geometry factor at various loads in sedge and alder peat soils. The measurements were conducted on undisturbed soil samples without applying a load and with loads corresponding to field overburden. The shape of the shrinkage characteristics of such soils were completely different from those of clay soils. The application of loads did not significantly influence the shrinkage characteristics curve. The applied load strongly influenced on relationship between shrinkage geometry factor and the moisture ratio, showing higher values of subsidence and lower values of crack volume in comparison with unloaded conditions.  相似文献   
40.
The influence of dusts from aluminium (AP), zinc and lead (ZP1, ZP2), sintering (SP) and power (PP) plants on organic matter accumulation on the forest floor of a mixed oak-pine forest was studied in Niepo?omice Forest near Kraków, Poland. An artificial application of the dusts on experimental plots was used corresponding to 100, 500, 1000, 2000, and 5000 t km?2. Increased organic matter accumulation was observed 5 yr following the addition of AP, ZP1 and ZP2 dusts, while SP and PP dusts at levels > 100 t km?2 caused a slight decrease in litter accumulation. Statistical analysis indicated that Cd, Mn, Pb and Zn present in industrial dusts were responsible for the increase in litter accumulation, while some nutrients (e.g. K, Mg, Na) contained in the dusts might decrease organic matter storage to some extent.  相似文献   
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