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J. E. Parlevliet 《Euphytica》2007,153(3):353-362
Improved cultivars loose their identity and healthiness unless maintained properly. Contaminating and degrading forces, such
as outcrossing, volunteer plants, mixing, natural selection, mutation and seed-borne diseases, are at the root of this. Maintenance
selection can prevent this deterioration. How it is carried out depends on the reproduction system of the crop. Crops are
therefore classified into four categories; typical cross-pollinating crops, self-pollinating crops with a substantial amount
of outcrossing, typical self-pollinating crops with little outcrossing, and the vegetatively reproduced crops.
Generally some of the “breeder seed” is used to plant a small plot with spaced plants. A fair number of healthy plants of
the cultivar type is selected and the seed is harvested per plant. The progenies of the selected plants are grown in small
plots. Non-uniform or deviating plots and plots with a seed-borne disease are removed. The seed of the progenies that are
healthy, uniform and similar (and so of the cultivar type) are harvested per progeny to be tested next season on larger plots.
The same selection is applied and only the seed of the progenies that are healthy, uniform and similar are harvested together
to produce the “breeder seed”. The details of this maintenance selection vary with the reproduction system, the multiplication
rate of the crop and the possibilities available to the breeder. Seven crops, potato, common bean, barley, wheat, faba bean,
quinoa and maize are discussed here as they represent the different reproduction systems and multiplication rates, while being
important Andean food crops. 相似文献
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利用3个耐盐小麦品种和4个普通丰产品种,按不完全双列混配法等量混配成12个二系混合种,在花碱地上研究了小麦二系混舍种的混合优势及其7个成员品种的生态组合力。结果表明,小麦二系混合种的混合优势普遍存在,且组合间的混合优势差异显著,平均优势幅度为—4.5%~20%,超亲优势为—12.3%~16.8%;生态组合力分析表明,成员品种间生态组合力差异显著,同一成员品种在不同的环境中生态组合力表现亦有差异。因此,在混配小麦二系混合种时,应选择生态组合力好的成员品种进行混配,这样会选出混合优势强的高产二系混合种。 相似文献
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水稻品种混合种植方式及增产效果的研究 总被引:1,自引:0,他引:1
本文通过不同形态特征和生理特性的中熟及中晚熟水稻品种混合种植的试验,提出了高秆大穗型品种与中矮秆多蘖、多穗型品种混播、混插;多品种以不同比例混插;多品种1:1混播混插等最优混种、混插方式;并得出了不同品种混种、混插方式的增产效果与增产比例;明确了混种、混插群体的抗病、抗倒伏能力。 相似文献
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Multi-parameter fingerprinting of sediment deposition in a small gullied catchment in SE Australia 总被引:4,自引:0,他引:4
The determination of relative contributions of potential sediment sources is an important step in the development of management strategies to combat soil erosion. In a 1.2 km2 gullied catchment in southeastern New South Wales, multi-parameter fingerprinting of sediment deposited in successive downstream pools has identified gully walls as the dominant sediment source when the grazed pasture surface was the only other potential source. The median fractional contributions remained relatively steady in the successive downstream pools, with the gully walls responsible for between 90% and 98% of the pool sediment. This result was achieved despite the ratio of the source areas varying considerably between successive nested subareas. Reliability bounds on the predictions, accounting for limited sampling of sources, were well constrained and varied between 5.4% and 13.8%. Downstream of an unsealed road crossing, sediment from the road source dominated the pool sediments such that contributions from the pasture surface and gully sources could not be determined. 相似文献
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牛鞭草种质资源在中国的分布及其人工草地建植技术 总被引:5,自引:0,他引:5
牛鞭草为一种高大型C4禾草,其分布较广,主要分布在热带、亚热带和北半球的温带湿润地区。牛鞭草在我国已知的有4种,各种的分布有所不同。牛鞭草由于适应性广、耐刈割、产量高、品质好,被广泛种植,但由于长期单一种植造成草地严重退化,从而影响了该草的产量和品质,因此本文还从牛鞭草的建植和管理技术方面作了一定的论述。 相似文献
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Thirty-seven varieties of a Mediterranean durum wheat collection grown in Tunisia and Spain were analysed for their allelic composition in prolamins, as well as their protein concentration, sodium dodecyl sulphate sedimentation (SDSS) test and mixograph parameters. Genotype was a greater source of variation in all measurements than locality. Uncommon high and low molecular glutenin subunits (HMW-GS and LMW-GS) were found (V and 2•• subunits at Glu-A1, 13 + 16 at Glu-B1, 5* subunit and ax allele at Glu-A3). The rare combinations 2 + 4+14 + 18 and 8 + 9+13 + 16+18 subunits at the Glu-B3 locus were found. Glu-A3ax had a positive influence on SDSS and mixograph parameters. Of all the prolamins, those that have the B-LMW-GS composition aaa (for Glu-A3, Glu-B3 and Glu-B2 loci, respectively), when associated with the Glu-A1c and Glu-B1d gave the best semolina quality. By contrast, semolina quality is poor when this same composition is associated with the Glu-A1c and Glu-B1e and even poorer when associated with the Glu-A1c and Glu-B1f. In addition, the cultivars with B-LMW-GS allelic composition aab (for Glu-A3, Glu-B3 and Glu-B2 loci, respectively), when associated with the Glu-A1c and Glu-B1d, gave high quality, whereas when associated with the Glu-A1c and Glu-B1e or with Glu-A1o and Glu-B1f, the quality was very poor. 相似文献
10.
有机肥对混推复垦地养分变化及生产力的影响 总被引:2,自引:0,他引:2
以混推复垦地为研究对象,通过对土壤养分的变化、作物长势和产量(生产力)及其经济效益进行分析比较,结果表明,增施有机肥量为18500,11000kg/hm2时,不论增施1年还是2年,仅表现出0~20cm土壤有效P显著高于对照(CK);增施有机肥量为11000kg/hm2时,不论增施1年还是2年,玉米株高在苗期、拔节期和抽雄期均显著高于对照(CK),且玉米产量和秸秆产量也表现出最高;增施有机肥量为11000kg/hm2时,连续2年的累计经济效益最优。 相似文献