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41.
东北草原植物残体腐解动态研究(简报) 总被引:10,自引:3,他引:10
东北草原植物残体腐解试验表明,植物残体腐解动态变化规律一致,前期腐解快、以后变慢。羊草的碳素残留率比草木樨的高,对于植物的不同器官残体,根的碳素残留率最高,茎次之,叶最低,试验结果还表明,植物残体不同埋深对碳素残留率也有影响,埋深7cm,植物残体的碳素残留率最低,埋深15cm稍高,覆盖在土壤表面的最高。这说明植物中的羊草、植物残体听 根和茎以及土壤深层的残体都有利于土壤有机质的积累,而草木樨、植物残体中的叶以及浅层植物残体都有助于养分向土壤释放,羊草和草木樨残体混合物的碳素残留率介于草木樨和羊草之间,说明羊草混种草木樨的共存对羊草残体的分解有利。 相似文献
42.
天然更新是森林恢复较好的办法,对未来林分结构和生物多样性具有深远的影响。更新模型能够模拟天然更新的现实和未来状况,为森林经营者提供准确的森林计划。以吉林省汪清林业局2013年设置的12块云冷杉针阔混交林为例,选择泊松和负二项分布形式,考虑样地间的随机效应,构建基于林分因子的云冷杉针阔混交林天然更新模型。结果表明:各个树种对林分因子的反应不一,白桦更新株数与林分每公顷株数和平均直径均呈负相关;红松和水曲柳更新株数不受各个林分因子的影响,更新株数是随机的;冷杉更新株数与林分每公顷断面积呈负相关;色木槭和云杉更新株数均与林分平均直径呈负相关。在考虑样地的随机截距效应后,模型的模拟效果显著提高。在构建天然更新模型时,林分密度是十分重要的因子,如果要人工促进天然更新,就要科学合理的采取经营措施,以确保合理的林分密度。另外样地间的差异是不容忽略的因素,需要利用混合效应模型方法来降低预测误差。 相似文献
43.
在崂山茶区采用网捕法和植株拍打法研究了种草和清耕茶园节肢动物数量的变化规律。结果表明,种植紫花苜蓿的第2年,节肢动物数量增加明显,种群结构趋于稳定。共调查到节肢动物12目,44科,81种,类群最大的为蜘蛛目,有27种,其次是同翅目,有12种,鞘翅目有10种,膜翅目有9种,其他23种。种草园与清耕园相比,节肢动物种类增加18.0%~19.0%,害虫数量平均减少75.6%,天敌种类增加10.3%~17.1%,个体数增加64.0%~77.1%,节肢动物数量在一年中的变化幅度平缓。茶园使用化学农药,是影响节肢动物数量的主要因素。在种植紫花苜蓿的茶园,不使用任何化学农药也不致造成害虫危害。 相似文献
44.
机电设备安装工程施工是一项技术领域的工作,涉及到了多个工种和多道工序,因此存在特殊的要求。文章对机电设备安装施工中存在的一些常见问题进行了分析,并为提高机电设备的安装质量提出了一些建议。 相似文献
45.
Sophie Miyumo Chrilukovian B. Wasike Evans D. Ilatsia Jörn Bennewitz Mizeck G. Chagunda 《Zeitschrift für Tierzüchtung und Züchtungsbiologie》2023,140(1):106-120
This study aimed at investigating the influence of genetic and non-genetic factors on immune traits to inform on possibilities of genetic improvement of disease resistance traits in local chicken of Kenya. Immune traits such as natural and specific antibodies are considered suitable indicators of an individual's health status and consequently, used as indicator traits of disease resistance. In this study, natural antibodies binding to Keyhole Limpet Hemocyanin (KLH-NAbs) was used to measure general disease resistance. Specific antibodies binding to Newcastle disease virus (NDV-IgG) post vaccination was used to measure specific disease resistance. Titers of KLH-NAbs isotypes (KLH-IgM, KLH-IgG and KLH-IgA) and NDV-IgG were measured in 1,540 chickens of different ages ranging from 12 to 56 weeks. A general linear model was fitted to determine the effect of sex, generation, population type, phylogenetic cluster, line, genotype and age on the antibody traits. A multivariate animal mixed model was fitted to estimate heritability and genetic correlations among the antibody traits. The model constituted of non-genetic factors found to have a significant influence on the antibody traits as fixed effects, and animal and residual effects as random variables. Overall mean (±SE) concentration levels for KLH-IgM, KLH-IgG, KLH-IgA and NDV-IgG were 10.33 ± 0.04, 9.08 ± 0.02, 6.00 ± 0.02 and 10.12 ± 0.03, respectively. Sex, generation and age (linear covariate) significantly (p < 0.05) influenced variation across all the antibody traits. Genotype effects (p < 0.05) were present in all antibody traits, apart from KLH-IgA. Interaction between generation and line was significant (p < 0.05) in KLH-IgM and NDV-IgG while nesting phylogenetic cluster within population significantly (p < 0.05) influenced all antibody traits, apart from KLH-IgA. Heritability estimates for KLH-IgM, KLH-IgG, KLH-IgA and NDV-IgG were 0.28 ± 0.08, 0.14 ± 0.06, 0.07 ± 0.04 and 0.31 ± 0.06, respectively. There were positive genetic correlations (0.40–0.61) among the KLH-NAbs while negative genetic correlations (−0.26 to −0.98) were observed between the KLH-NAbs and NDV-IgG. Results from this study indicate that non-genetic effects due to biological and environmental factors influence natural and specific antibodies and should be accounted for to reduce bias and improve accuracy when evaluating the traits. Subsequently, the moderate heritability estimates in KLH-IgM and NDV-IgG suggest selection possibilities for genetic improvement of general and specific immunity, respectively, and consequently disease resistance. However, the negative correlations between KLH-NAbs and NDV-IgG indicate the need to consider a suitable approach that can optimally combine both traits in a multiple trait selection strategies. 相似文献
46.
文章结合辽阳地区农业机械化实际,从培育新型农业主体,构建新型农业服务体系和培养新型的农机技术人员三方面做了现状分析,论述了农机作业质量的重要性及发挥农机化作用的思考,旨在充分发挥农业机械化在农业科技创新中的主导作用。 相似文献
47.
48.
Zhao Tingchao Huang Shanglian Chen Weimin 《保鲜与加工》1997,(5):104-109
The paper discuss the concept of fiberoptic smart civil structure,and analysis the principle of non destructive evaluation of civil structure with the help of embeded fiberoptic sensor in sensing the inner state and integrity of the structure.The typical experiment and development of fiberoptic sensing system in the health monitoring of dam,highway,bridge and buildings are overriewed. 相似文献
49.
Wang Yuanliang Li Shiqi 《保鲜与加工》1992,(2):116-121
Several aspects of the conditional equation derived from the accumulative equation are discussed in detail. The results indicate that the conditional equation not only is well consistent with the principles of electronegativity and absolute hardness equalization, but also satisfies the bonding of a full -prerequisite condition, e. g. two like electronic charge species repel and unlike attract each other'. In addition these principles are in the accumulative state. Mathematically, some other aspects of the conditional equation are worth studying based on the generalization of this equation. 相似文献
50.
There are several methods to cope with the common problem of the uneven subsidence of foundation. The reason for uneven settlement of foundation of the frame structure was analyzed in this paper. Considering the limitation of the construction site and the principle of consolidation, a feasible reinforcement measure was taken. Meanwhile, a practical construction pattern was chosen upon the comparison of the reinforcement technology analysis and the construction method. The observation of the settlement result after consolidation of the structure shows that the result of this reinforcement treatment pattern is effective. 相似文献