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排序方式: 共有74条查询结果,搜索用时 15 毫秒
1.
Heterodera glycines is not known to occur in South-east Asian countries except in Indonesia. Specific surveys carried out recently in central India indicate absence of the nematode. The region has a large area under cultivation of soybean, and also other crop and wild hosts. H. glycines causes annual yield losses of about half a million metric tons in 10 major soybean-growing countries. Asia has to import half its demand of soybeans, mainly from North America and Brazil, where H. glycines occurs. Spread is mainly through soil mixed with seeds, or by spillage of grain. A preliminary pest risk analysis suggests that the South-east Asian region is suitable for the introduction and spread of H. glycines . Management practices are suggested to delay its introduction. 相似文献
2.
Effect of tillage and mode of straw mulch application on soil erosion in the submontaneous tract of Punjab, India 总被引:6,自引:0,他引:6
The submontaneous tract of Punjab comprising 10% of the state, is prone to soil erosion by water. Soils of the area are coarse in texture, low in organic matter and poor in fertility. High intensity rains during the monsoon season result in fertile topsoil removal. There is an urgent need to control soil erosion in this region so as to improve soil productivity. A field study was conducted to estimate the effect of tillage and different modes of mulch application on soil erosion losses. Treatments comprised two levels of tillage, viz. minimum (Tm) and conventional (Tc) in the main plots and five modes of straw mulch application, viz. mulch spread over whole plot (Mw), mulch spread on lower one-third of plot (M1/3), mulch applied in strips (Ms), vertical mulching (Mv) and unmulched control (Mo), in subplots in a replicated split plot design. Rate of mulch application was 6 t ha−1 in all modes. Compared with Mo, Mw reduced runoff by 33%. Runoff and soil loss were 5 and 40% higher under Tc than under Tm. Though other modes of straw mulch application (M1/3, Ms and Mv) controlled soil loss better than Mo, their effectiveness was less than Mw. Tm was more effective in conserving soil moisture than Tc. Compared with Mo, Mw had 3–7% higher soil moisture content in the 0–30 cm soil depth under Tm. Minimum soil temperature of the surface layer was 1.4–2.4 °C lower under Mw than under Mo. Straw mulching reduced maximum soil temperature and helped in conserving soil moisture. Minimum tillage coupled with Mw was highly effective in reducing soil erosion losses, decreasing soil temperature and increasing moisture content by providing maximum surface cover. 相似文献
3.
Rajan 《EPPO Bulletin》2006,36(1):59-64
Surveillance of pests is an important activity for (a) early detection and prevention of spread of indigenous and exotic pests, (b) delimiting pest distribution, (c) searching for pest free areas for meeting the requirements of national and international trade and (d) to achieve effective management of pests that affect crop production. Recent developments on these topics are reviewed with special reference to plant parasitic nematodes in India. 相似文献
4.
Fleischer RL Price PB Walker RM Filz RC Fukui K Friedlander MW Holeman E Rajan RS Tamhane AS 《Science (New York, N.Y.)》1967,155(3759):187-189
Cosmic ray nuclei have been observed with the use of plastic trackdetecting solids in satellites and high-altitude balloon flights. Nuclear emulsions in the stacks of plastic sheets allowed the positive identification of cosmic raynuclei as light as nitrogen. The most striking new information was the failure to observe relativistic iron nuclei, a result which has led to an advance in the understanding of track registration criteria. 相似文献
5.
A mycosis in larval tiger prawn, Penaeus monodon Fabricius, is described for the first time from India. The hyphae of Lagenidium callinectes are contorted, irregularly branched, sparingly septate, and contain a cell wall and membrane, vacuoles, mito chondria, ribosomes, small and large vesicles, and Woronin bodies. The spores occur singly or in pairs. The fungal mycelium may either invade and embed itself in the tissues, or alternatively, replace all the muscle tissues of the infected larval P. monodon. Fungus infected, untreated populations of nauplii, zoea and myksis exhibited mortalities of 5.33 ± 0.55%, 24.68 ± 4.58% and 47.89 ± 0.27%, respectively. A 0.5 ppm treatment with trifluralin significantly reduced the mortality of infected larval populations (i.e. 1.1% nauplii, 3.28% zoea and 5.21% myksis mortality). Lagenidium sp. exhibited growth in potato dextrose agar medium and in Sabouraud's agar at 28 °C. 相似文献
6.
Two lactational intramammary antibiotic preparations (cloxacillin and oxytetracycline) were each used to treat eight goats by intramammary infusion in one half. The rate of release of the antibiotics was monitored by a diffusion assay based on the sensitive organism Bacillus stearothermophilus var. calidolactis. Cloxacillin was still detectable 156 hours after the final treatment while oxytetracycline was undetectable 108 hours following treatment. A small but significant amount of antibiotic was translocated between treated and untreated halves of the udder in both cases. 相似文献
7.
Craters attributable to hypervelocity impacts of micrometeorites have been discovered on rare chondrule-like objects from the gas-rich meteorite Kapoeta. These chondrule-like objects, probably generated by impacts themselves, provide further evidence for the regolith origin of Kapoeta. The micrometeorite flux at the time of formation of the meteorites was probably an order of magnitude higher than the present flux, but the solar luminosity could not have been higher than 1.7 times its present value. 相似文献
8.
Twenty nine germplasm lines of Chenopodium quinoa and two of Chenopodium berlandieri subsp. nuttalliae were evaluated for 12 morphological and 7 quality traits for two test seasons. The 19 traits were analyzed for cluster and
principal component analysis. The first four PCs contributed 78.70 % of the variability among the germplasm lines. The first
PC accounted for 39.5% of the variation and had inflorescence/plant, plant height and stem diameter as the traits with largest
coefficients, all with positive sign. The characters with greatest positive weight on PC2 were days to maturity (0.309), inflorescence length (0.260) and branches/plant. All the germplasm lines were grouped into
six clusters based on average linkage method. Cluster III had high values for seed yield and most of the quality traits but
showed a small seed size. The dendrogram separated the two lines of C. berlandieri subsp. nuttalliae from the quinoa lines. 相似文献
9.
10.
Godswill Makombe Johannes M. Makadho Rajan K. Sampath 《Irrigation and Drainage Systems》1998,12(3):253-263
This paper analyses the water management performance of small holder irrigation systems in Zimbabwe. The government and farmer managed systems are compared in terms of their ability to match desired with actual water supply. Desired supply is defined as crop water requirements adjusted downwards by rainfall where relevant. The Theil measure of accuracy of forecasts is used to calculate the error committed by each system in trying to match water supply and demand. The analysis shows that, everything else being equal, the farmer managed system performs better than the government system in matching supply and demand. This means that the farmer managed systems should be encouraged for future small holder irrigation development in Zimbabwe. 相似文献