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1.
采用真空复合轧制工艺,将3种钢板(GCr15、Q420、IF)轧制成梯度复合材料,对其结合界面处的微观组织、成分及硬度分布、抗剪强度进行了检测,并对梯度材料自磨锐割刀进行了田间试验。结果表明,不同板层界面处材料间相互咬合形成较为紊乱的冶金结合方式,界面处元素相互扩散形成过渡区,组织缺陷较少。结合界面处的抗剪强度均超过了国标要求,且断裂方式为韧性断裂,不同界面间存在较为平缓的硬度梯度变化。梯度材料自磨锐割刀后刀面、刀尖及刃口材料为GCr15钢,硬度高、耐磨性好,前刀面的硬度呈梯度变化,磨损均匀,作业过程中可始终保持刀尖前凸,刃口曲率半径变化较小,能够长时间保持刃口的锋锐性与再生作物的低损伤切割。田间试验结果表明,相同作业条件下,梯度材料自磨锐割刀耐磨性是市售割刀的3倍以上。 相似文献
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Seed yield is a major breeding target in tetraploid red clover. We investigated if marker‐assisted parentage analysis can identify progeny plants with two high seed‐yielding parents in tetraploid red clover and if this technique is more advantageous than traditional half‐sib selection. Parentage analysis was successfully performed on the progeny from the 10% highest seed‐yielding genotypes from a second‐cycle family selection trial: 16.0% of progeny were identified with a high seed‐yielding father. However, progeny plants with two high seed‐yielding parents did not produce more seeds than traditionally selected progeny (27.3 g vs. 30.7 g/plant, respectively). The 10% highest seed‐yielding genotypes displayed on average 2% self‐fertilization. Four genotypes were self‐fertile with individual selfing rates up to 20%. Our results discourage the use of marker‐assisted parentage analysis to improve seed yield in tetraploid red clover when the material has been preselected for seed yield. Breeders should be aware that intensive selection for seed yield in tetraploid red clover may inadvertently lead to selection for increased self‐fertility, which may increase inbreeding in the long term. 相似文献
3.
基于部首嵌入和注意力机制的病虫害命名实体识别 总被引:1,自引:0,他引:1
为了解决农业病虫害命名实体识别过程中存在的内在语义信息缺失、局部上下文特征易被忽略和捕获长距离依赖能力不足等问题,以农业病虫害文本为研究对象,提出一种基于部首嵌入和注意力机制的农业病虫害命名实体识别模型(Chinese agricultural diseases and pests named entity recognition with joint radical embedding and self attention, RS-ADP)。首先,该模型将部首嵌入集成到字符嵌入中作为输入,用以丰富语义信息。其中,针对部首嵌入设计了3种特征提取策略,即卷积神经网络(Convolutional neural network, CNN)、双向长短时记忆网络(Bidirectional long short term memory network, BiLSTM) 和CNN-BiLSTM;其次,采用多层不同窗口尺寸的CNNs层提取不同尺度的局部上下文信息;然后,在BiLSTM提取全局序列特征的基础上,采用自注意力机制进一步增强模型提取更长距离依赖的能力;最后,采用条件随机场(Conditional random field, CRF)联合识别实体边界和划分实体类别。在包含11个类别和24715条标注样本的农业病虫害自制语料上进行了实验。结果表明,本文模型RS-ADP在该数据集上精确率、召回率和F1值分别为94.16%、94.47%和94.32%;在具体实体类别上,RS-ADP在作物、病害、虫害等易识别实体上F1值高达95.81%、97.76%和97.23%。同时,RS-ADP在草害、病原等难以识别实体上F1值仍保持86%以上。实验结果表明,本文所提模型能够有效识别农业病虫害命名实体,其识别精度优于其他模型,且具有一定的泛化性。 相似文献
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许添元 《安徽农业大学学报》2016,(3):77-81
企业未办理营业执照就进行生产,工人工作时受伤,本应按照《工伤保险条例》进行赔偿,适用无过错原则。然而,一些基层法院认为,双方形成了个人之间的劳务关系,应按《侵权责任法》的规定,适用过错相抵原则,这严重损害了劳动者的合法权益。劳动关系与劳务关系相比较,劳动关系具有产业性、劳动者的从属性、生产的组织性和期限的长期性等特征。通过对劳动关系内涵的分析,有助于我们正确处理案件,就不会错误地将本是劳动关系的案件认定为双方存在劳务关系,也不会将工伤案件按劳务关系处理。 相似文献
7.
Ariana M. Cachi Ana Wünsch Antoni Vilanova Merce Guàrdia Marta Ciordia Neus Aletà 《Plant Breeding》2017,136(1):126-131
Prunus avium is primarily cultivated for its fruit, sweet cherries. However, it is also used to produce high‐quality timber. In a P. avium seed orchard, gametophytic self‐incompatibility is a restriction for free pollen flow and should be considered when establishing basic forest materials. In this study, S‐locus diversity and cross‐incompatibility of wild cherry individuals in clonal banks established for breeding for timber production were investigated. Wild cherry trees (140) with outstanding forest growth habit, collected in northern Spain, grafted and planted in two clonal banks, were genotyped at the S‐locus. The self‐incompatibility S‐locus genes, S‐RNase and SFB, were analysed by PCR. Twenty‐two S‐haplotypes, resulting in 72 different S‐genotypes, were identified. The genotypes were grouped into 33 incompatibility groups and 39 unique genotypes. This initial S‐locus analysis revealed large genetic diversity of wild cherry trees from the Spanish northern deciduous forest, and provides useful information for seed orchard design. Wild P. avium displays significantly more genetic diversity than what is detected in local cultivars, revealing a narrowing of genetic diversity during local domestication. 相似文献
8.
D. M. Hogarth 《Euphytica》1980,29(3):737-746
Summary The diallel cross was found to be an unsuitable design for quantitative genetic analyses with sugar cane.Accidental selfing caused substantial inbreeding depression for most characters. Consequently, analysis of a diallel cross without regard to the effect of accidental selfing would be subject to bias, if accidental selfing were common. A selfing model proposed by Dudley (1963) was extended to include differential selfing, and was tested in an experiment in which the percentage of selfing in each cross was estimated visually.Variance components had large standard errors, which prevented firm conclusions from being drawn, but selfing appeared to cause substantial bias in the estimates. Estimates of genetic variance components from a p(p-1) diallel set, using the extended selfing model, were compared with estimates obtained from the standard analyses in which reciprocal or maternal effects should account for the effect of selfing. The estimates were comparable, but the standard analyses were simpler and produced estimates with lower standard errors.When the effects of selfing were minimized, general combining ability (g.c.a.) effects appeared to be much more important than specific combining ability (s.c.a.) effects for most characters. 相似文献
9.
Summary Highly pseudo-self compatible (PSC) Nemesia strumosa plants were selfed and intercrossed to produce progenies of the F5 through F7 generations. Though high PSC progenies were obtained, none were truebreeding. Progenies from crossing inbred high PSC plants to low PSC plants consisted of either mostly low PSC plants or both low and intermediate plants. A backcross to the high PSC parent of a progeny from a low times high cross produced a family with a PSC frequency distribution skewed toward low PSC but with a few high PSC plants. These data may be explained if PSC genes at some or most loci are incompletely dominant to non-PSC genes and threshold numbers of PSC genes are required for PSC expression and for 100% PSC plants. Dominance may also occur at some loci. Although only a small number of genes may be required to produce a high PSC plant, the total number of PSC genes may be large.Scientific Journal Series Paper No. 11,676 of the Minnesota Agricultural Experiment Station. 相似文献
10.
余旌胡 《湖南农业大学学报(自然科学版)》1999,26(1)
定义了箱维数,研究了其性质,并获得了Hausdorff维数和Packing维数的另一表达式。最后,计算了一类子集的分数维。 相似文献