排序方式: 共有33条查询结果,搜索用时 218 毫秒
1.
报道12个脐橙品系高接树的生长、嫁接亲和力、抗逆性、产量和果实品质,最后讨论了发展脐橙应注意的问题。 相似文献
2.
应用免疫细胞化学方法对白血病抑制因子(leukemia inhibitory factor, LIF)、白血病抑制因子受体(leukemia inhibitory factor receptor, LIFR)和gp130在月经周期猕猴卵巢内的表达进行了研究。结果表明:LIF、LIFR和gp130在猕猴卵巢内的表达量随月经周期的不同而变化,LIF及其受体在增殖期卵巢内的表达量高于分泌期的卵巢。LIF及其受体在原始卵泡、腔前卵泡和有腔卵泡的卵细胞内表达量均较高,在颗粒细胞、卵泡膜、卵巢生殖上皮和卵巢基质中有少量表达,而在闭锁卵泡、退化的黄体和卵巢髓质中未见表达。LIF及其受体在猕猴卵巢内的表达可能受卵巢分泌的类固醇激素所调控,LIF可能通过自分泌或旁分泌的方式在猕猴卵泡发育及排卵等过程中起重要作用。 相似文献
3.
一般来说,家禽饲养的最佳温度为20~25℃、湿度为50%~70%。温度过高会降低生产性能,严重时会造成家禽死亡。因此采用有效的降温措施是夏季家禽生产的关键。多年的实践表明,风机-水帘通风冷却系统是目前最经济有效的降温模式之一。本文就该系统的原理和设计使用要点加以介绍。 相似文献
4.
5.
6.
[目的] 黄土丘陵区“治沟造地”工程形成的部分新造耕地面临着土壤盐碱化的风险,探究新造耕地土壤水盐空间分异特征及其影响因素,为预防和防治土壤盐碱化,促进新造耕地可持续利用提供理论依据。[方法] 选择该区典型新造耕地,沿沟头至沟口设置6个试验小区,依次为采样点1,2,3,4,5,6,利用网格法获取每个小区0—20,20—40 cm深度的土壤样品,采用多重分形方法分析新造耕地土壤水、盐空间分异特征。[结果] 新造耕地土壤水、盐含量沿沟头至沟口皆逐渐降低,采样点1,2,3地块的平均土壤水分和平均盐分含量分别为17.6%和0.81 g/kg,分别比采样点4,5,6地块的平均值高23.0%和14.1%(p<0.05)。采样点1,2,3地块土壤水、盐的多重分形参数D1小于采样点4,5,6地块,而ΔD表现出相反的结果,表明采样点1,2,3地块土壤水、盐的空间变异性均较高。浅的地下水影响深度是促进采样点1,2,3地块盐分在表层土壤积累的主要原因(p<0.05);地形特征也是一个重要原因,采样点1,2,3地块地形狭窄,不利于排水,易发生涝渍,加剧了盐分积累(p<0.05)。此外,采样点1,2,3地块可能受到较高盐分含量的坡面径流和泥沙侵入,提高了该区域土壤水、盐分含量及其变异性。[结论] 地下水影响深度、地形特征及坡面径流泥沙是造成采样点1,2,3地块土壤水、盐含量及其空间变异性较高的重要原因。因此,靠近沟头位置的新造耕地是未来土壤盐碱化预防的重点区域。 相似文献
7.
Nartey Obemah David Liu Deyan Luo Jiafa Lindsey Stuart Di Hong J. Chen Zengming Yuan Junji He Tiehu Ding Weixin 《Journal of Soils and Sediments》2021,21(6):2381-2393
Journal of Soils and Sediments - The impact of dairy farm effluent and manure applications upon gas emissions from soil is of concern for agronomic, ecological, and environmental reasons. Yet it... 相似文献
8.
本实验研究了氨水处理引起类坏死的蝌蚪皮肤在恢复过程中碱性磷酸酶的活性变化。发生类坏死的皮肤中,细胞间隙及胶原纤维上的酶活性增强,但连接复合体及细胞表面处的活性则降低。恢复1h 后,细胞间隙及胶原纤维上的活性有所减弱;恢复5h 后,细胞表面、连接复合体及细胞间隙处的酶活性都已接近正常皮肤的水平。我们认为发生类坏死的皮肤在结构及酶活性上都可以恢复。 相似文献
9.
Yield-scaled nitrous oxide emissions from nitrogen-fertilized croplands in China: A meta-analysis of contrasting mitigation scenarios 总被引:1,自引:0,他引:1
Garba ALIYU Jiafa LUO Hong J. DI Deyan LIU Junji YUAN Zengming CHEN Tiehu HE Weixin DING 《土壤圈》2021,31(2):231-242
Nitrogen(N) losses in cropland resulting from the application of synthetic fertilizers decrease crop productivity and exacerbate environmental pollution.Mitigation measures, such as reduction in N fertilizer application rates, can have unintentional adverse effects on crop yield. We conducted a meta-analysis of soil N2O emissions from agricultural fields across China under contrasting mitigation scenarios as a novel approach to identify the most effective strategy for the mitigation of emissions of N2O derived from N fertilizer use in China. Current standard agricultural practice was used as a baseline scenario(BS), and 12 potential mitigation scenarios(S1–S12) were derived from the available literature and comprised single and combinations of management scenarios that accounted for crop yield. Mitigation scenarios S6(nitrification inhibitor 3,4-dimethylpyrazole phosphate) and S11(20% reduction in N application rate plus nitrification inhibitor dicyandiamide) in maize, rice, and wheat crops led to an average 56.0% reduction in N2O emissions at the national level, whereas scenario S4(nitrification inhibitor dicyandiamide) led to yield optimization, with a 14.0% increase for maize and 8.0% increase for rice as compared to the BS. Implementation of these most effective mitigation scenarios(S4, S6, and S11) might help China, as a signatory to the 2015 United Nations Framework Convention on Climate Change(Paris Agreement), to achieve a 30% reduction in N2O emissions by 2030. 相似文献
10.