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941.
942.
Debate surrounding the nature of equine melanoma has resulted in an underestimation of its life‐threatening potential. Contrary to popular dogma, the variable, often slow, rate of growth commonly associated with equine melanoma does not warrant benign classification. Equine melanoma is a malignant neoplasm with the capacity for local invasion and metastasis. A classification scheme was proposed in 1995, but this does not address the progressive nature of equine malignant melanoma (EMM). Additionally, frustration with conflicting therapeutic recommendations has led many practitioners to inappropriately advocate benign neglect. This article addresses the need for a clinically applicable, standardised classification system, provides a review of current therapies and recommendations for equine practitioners, and comments on the future directions of EMM research.  相似文献   
943.
A 13-year-old Percheron gelding was presented for refractory gastric impaction. At necropsy a pedunculated 10 cm × 11 cm × 14 cm mass, histologically identified as an inflammatory polyp, was suspected to have been partly obstructing the pylorus. This is the first report of a polyp resulting in gastric outflow obstruction in a horse.  相似文献   
944.
945.
SUMMARY

The improvement in shoot production of filbert (Corylus avellana L.) adult tissues by sequential in vitro subcultures and intensive pruning was studied. Improved and sustained production of adult shoots is possible by repeated subculturing in the presence of high cytokinin concentrations, which seem important for stabilizing the response and inducing a transient increase in proliferation. Intensive pruning increases proliferation in initial explants and facilitates the establishment and maintenance of culture lines. Rooting capacity is also enhanced by sequential in vitro subcultures, but stabilizing the response takes longer than with shoot proliferation. The increased capacity of adult tis-sues for shoot proliferation and rooting are similar to those obtained using juvenile plants as a source of explants, and could be explained as a reinvigoration induced by in vitro sequential subcultures.  相似文献   
946.
Uittreksel

Evapotranspirasie in drie plantgemeenskappe van ‘n R. trichotomum habitat, naamlik, suiwer gras, suiwer R. trichotomum en ‘n gemengde stand van R. trichotomum en gras is gedurende die 1985–86 groeiseisoen bestudeer. Drie persele van elke plantgemeenskap is hidrologies geisoleer, besproei en die grondwaterinhoud is oor tyd met ‘n neutronvogmeter gemeet. Evapotranspirasie is met behulp van die grond water balansvergelyking bereken.

Die grasgemeenskap het gedurende die groeiseisoen deurgaans meer water verbruik as die R. trichotomum gemeenskap. Die waterverbruik van ‘n digte stand R. trichotomum is wel hoog genoeg om die vestiging van grasse onder normale reënvaltoe‐stande feitlik onmoontlik te maak.

Die onderdrukkende effek van R. trichotomum op grasproduksie, asook van ‘n digte grasstand op die groei van R. trichotomum word bespreek.  相似文献   
947.
948.
In the study of nutritional variability in potato it is desirable to know the present range of expression and genetic potential for increase. Potato breeding lines and varieties in two separate trials were evaluated for potassium and phosphorus content by wet ashing and Inductively Coupled Argon Plasma Emission Spectrophotometer analysis. Stability and broad-sense heritability were determined. Among genotypes, potassium content ranged from 1.85 and 2.49 % DW while phosphorus content ranged from 0.16 to 0.34 % DW over both trials. Genotype by environment interactions were significant in the Tri-State and Western Regional Red/Specialty (WR-R/SP) trials for both potassium and phosphorus, while environments were not. Genotype was a significant source of variation for both minerals in the WR-R/SP trial only. In the Tri-State trials, 7 and 4 of ten clones were unstable before and after removal of environmental heterogeneity, respectively, for potassium content, and 5 and 4 genotypes were unstable before and after removal of environmental heterogeneity, respectively, for phosphorus. In the WR-R/SP Trials, 7 and 3 of 13 clones were unstable before and after removal of environmental heterogeneity, respectively, for potassium content, and 3 and 4 genotypes were unstable before and after removal of environmental heterogeneity, respectively, for phosphorus. Broad sense heritability was low for both potassium and phosphorus in the Tri-State Russet-Skin Trials but high for both potassium and phosphorus in the WR-R/SP Trials. Although potato is a minor contributor of phosphorus to the human diet, it is an important source of potassium. Adult males and females receive 12 % of the Recommended Dietary Allowance of potassium from 100 g of potato. Estimates of broad-sense heritability from these two trials suggest that genotypes with higher levels of both potassium and phosphorus can be selected from within the Red/Specialty market class, but not from within the Tri-State russet class. An increase in potassium content in the potato, for which the daily need in the human body is so high, could be a boon to human health.  相似文献   
949.
Urine patches in dairy pastures are major sources of nitrous oxide (N2O). Wet winters result in compaction damage to pastures because of animal trampling. The nitrification inhibitor, dicyandiamide (DCD), is effective at reducing N2O emissions from urine patches. Here, we assessed the extent of damage to the physical quality of the soil by trampling and whether this influenced the ability of DCD to mitigate N2O emissions. A field experiment was conducted where a sandy loam soil was trampled by a mechanical hoof just before urine and DCD application. Trampling reduced air permeability and pore continuity, but this had no effect on bulk density. Urine appeared to have contributed to pore collapse and blockage. Trampling increased average cumulative N2O emissions from 1.74 to 4.66% of urine‐N applied. This effect was attributed to increased water‐filled pore space, aggregate destruction and suppression of grass growth. DCD was highly effective in reducing N2O emissions, with the N2O emission factor of the urine‐N being decreased by 58–63%. Trampling did not significantly affect the effectiveness of DCD in reducing N2O emissions.  相似文献   
950.
J.  D.  White  B.  R.  Moore 《农业科学与技术》2010,(5):1-9
Carbon budget changes were measured on a farm near Robinson, Texas, where land originally tilled for hay production was abandoned over time periods of 10, 20, and 35 years followed by succession of prairie and forest vegetation. Woody biomass accumulation increased following abandonment from 0.14 kg C m2 yr~ during forest initiation to 0.57 kg C m2 yr-1 of the mature forest Soil carbon was highest in the tilled field ( 15.77 kg C m2) with lowest in the grassland ( 11.66 kg C m-2). Soil nitrogen was highest in the tilled field (0.55 kg N ms) and lowest in the forest transition (0.38 kg N m2). Soil C:N ratios were highest in the forest transition (C:N=36) and lowest in the grassland (C:N=22). Soil respiration was constant across the site with an annual average value of 1.46 kg CO2-C m-2 yr-. Results show that land in this region may be a source of carbon for several decades following abandonment due to enhanced soil carbon emissions as a function of nutrient input shifts.  相似文献   
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