为明确不同施氮量下糜子生长规律、产量表现以及氮素利用效率,分析糜子形态特征与产量和氮素利用的关系,同时确定宁夏引黄灌区麦后复种糜子的适宜施氮量,本研究于2019年和2020年以宁糜9号为材料,2019年设0 (N0)、90 (N1)、120 (N2)和150...为明确不同施氮量下糜子生长规律、产量表现以及氮素利用效率,分析糜子形态特征与产量和氮素利用的关系,同时确定宁夏引黄灌区麦后复种糜子的适宜施氮量,本研究于2019年和2020年以宁糜9号为材料,2019年设0 (N0)、90 (N1)、120 (N2)和150 kg hm^(-2) (N3)纯氮水平,2020年增设180 (N4)和210 kg hm^(-2) (N5)纯氮水平,以不施氮肥(N0)为对照在宁夏引黄灌区进行大田试验。结果表明,施氮显著促进糜子各生育时期株高、茎粗、叶面积、根系的生长和干物质的积累,但当施氮量超过150kghm^(–2)时,除茎粗和叶面积外,其余各生长指标出现下降趋势;根冠比随施氮量的增加呈先降低后升高再略微下降趋势,多数生育时期在N2处理根冠比达最小值,拔节期、抽穗期、灌浆期和成熟期分别为0.119、0.087、0.054和0.052。施氮显著促进糜子产量、千粒重和穗粒数增加,并且随施氮量的增加呈先增加后略微下降趋势,N2、N3处理促进效果最佳;N2、N3处理糜子产量分别为2979.41kghm^(–2)、3084.67 kg hm^(-2),较N0处理分别增产76.22%、83.21%。糜子的氮素收获指数、氮肥表观回收率、农学利用率和偏生产力在N2处理表现较好,分别为60.23%、61.81%、10.77 kg kg^(-1)、24.83 kg kg^(-1)。进一步分析发现,糜子产量与各生长指标显著正相关,各生长指标之间显著正相关,根系形态特征与氮素积累量显著正相关,表明施氮可以通过改善糜子根系形态特征来促进氮素吸收,进一步促进冠层的生长,从而有利于产量的形成。因此,适量施氮明显改善糜子生长状况、提高产量,并且有效平衡产量和氮素利用效率。综合来看,宁夏引黄灌区麦后复种糜子的合理施氮量为120~150 kg hm^(–2)。展开更多
A pretreatment process for hydrogen peroxide （H2O2） was optimized to enhance the biodegradation performance of rice straw and increase biogas yield. A determination experiment was conducted under predicted optimal c...A pretreatment process for hydrogen peroxide （H2O2） was optimized to enhance the biodegradation performance of rice straw and increase biogas yield. A determination experiment was conducted under predicted optimal conditions. Optimization was implemented using response surface methodology. The effects of biodegradation and the interactive effects of pretreatment time （PT）, H2O2 concentration （HC）, and substrate to inoculum ratio （S/I） on methane yield were investigated. The lignin, cellulose, and hemicellulose of rice straw were significantly degraded with increasing HC. The optimal conditions for the use of pretreated rice straw in anaerobic digestion were a 6.18-d PT, 2.68% HC （w/w total solid）, and 1.08 S/I; these conditions result in a methane yield of 288 mL g-1 volatile solids （VS）. A determination coefficient of 95.2% was obtained, indicating that the model used to predict the anabolic digestion process has a favorable fit with the experimental parameters. The determination experiment resulted in a methane yield of 290 mL g-1 VS, 88.0% higher than that of untreated rice straw. Thus, H2O2 pretreatment of rice straw can be used to improve methane yields during biogas production.展开更多
文摘目的分析境外染疫疑似人员新型冠状病毒肺炎(corona virus disease 2019,COVID-19)及非新冠社区获得性肺炎(community-acquired pneumonia,CAP)临床特征及流行病学特点,探讨早期诊断方法。方法回顾性分析2020年2月27日至2020年11月1日收治的符合留观病例标准的432例境外COVID-19染疫疑似人员的临床特征、流行病学史、实验室和胸部CT影像检查。其中CAP患者78例(18.06%):COVID-19患者12例(2.78%),非新冠CAP患者66例(15.28%)。结果COVID-19组50.0%患者入境前14天内有新冠流行病史较CAP组(15.15%)明显增多;归国途中起病患者6例(占50.0%)较CAP组(占21.21%)明显增多;发热、畏寒、头痛较CAP组明显增多;外周血淋巴细胞数目(1.33±0.61 vs 1.98±0.67)(*10^9/L)及血小板数目(198.25±49.36 vs 260.14±79.16)(*10^9/L)较CAP组明显降低;COVID-19组病变多累及双肺多叶,多位于胸膜下,磨玻璃密度影(ground-glass opacity,GGO)表现为主(50.0%)。CAP组病变多累及单侧肺单叶,多任意分布,渗出样表现为主(63.64%)。结论境外染疫疑似人员CAP发病率高,COVID-19是CAP其中一种。尽早开展核酸检测及胸部CT影像学检查,排除COVID-19,并行血常规检查,排除非新冠的CAP。
文摘为明确不同施氮量下糜子生长规律、产量表现以及氮素利用效率,分析糜子形态特征与产量和氮素利用的关系,同时确定宁夏引黄灌区麦后复种糜子的适宜施氮量,本研究于2019年和2020年以宁糜9号为材料,2019年设0 (N0)、90 (N1)、120 (N2)和150 kg hm^(-2) (N3)纯氮水平,2020年增设180 (N4)和210 kg hm^(-2) (N5)纯氮水平,以不施氮肥(N0)为对照在宁夏引黄灌区进行大田试验。结果表明,施氮显著促进糜子各生育时期株高、茎粗、叶面积、根系的生长和干物质的积累,但当施氮量超过150kghm^(–2)时,除茎粗和叶面积外,其余各生长指标出现下降趋势;根冠比随施氮量的增加呈先降低后升高再略微下降趋势,多数生育时期在N2处理根冠比达最小值,拔节期、抽穗期、灌浆期和成熟期分别为0.119、0.087、0.054和0.052。施氮显著促进糜子产量、千粒重和穗粒数增加,并且随施氮量的增加呈先增加后略微下降趋势,N2、N3处理促进效果最佳;N2、N3处理糜子产量分别为2979.41kghm^(–2)、3084.67 kg hm^(-2),较N0处理分别增产76.22%、83.21%。糜子的氮素收获指数、氮肥表观回收率、农学利用率和偏生产力在N2处理表现较好,分别为60.23%、61.81%、10.77 kg kg^(-1)、24.83 kg kg^(-1)。进一步分析发现,糜子产量与各生长指标显著正相关,各生长指标之间显著正相关,根系形态特征与氮素积累量显著正相关,表明施氮可以通过改善糜子根系形态特征来促进氮素吸收,进一步促进冠层的生长,从而有利于产量的形成。因此,适量施氮明显改善糜子生长状况、提高产量,并且有效平衡产量和氮素利用效率。综合来看,宁夏引黄灌区麦后复种糜子的合理施氮量为120~150 kg hm^(–2)。
基金financially supported by the Key Technologies R&D Program of China during the 11th Five-Year Plan period (2011BAD15B03)the Basic Scientific Fund of Northwest A&F University of China (QM2012002)
文摘A pretreatment process for hydrogen peroxide （H2O2） was optimized to enhance the biodegradation performance of rice straw and increase biogas yield. A determination experiment was conducted under predicted optimal conditions. Optimization was implemented using response surface methodology. The effects of biodegradation and the interactive effects of pretreatment time （PT）, H2O2 concentration （HC）, and substrate to inoculum ratio （S/I） on methane yield were investigated. The lignin, cellulose, and hemicellulose of rice straw were significantly degraded with increasing HC. The optimal conditions for the use of pretreated rice straw in anaerobic digestion were a 6.18-d PT, 2.68% HC （w/w total solid）, and 1.08 S/I; these conditions result in a methane yield of 288 mL g-1 volatile solids （VS）. A determination coefficient of 95.2% was obtained, indicating that the model used to predict the anabolic digestion process has a favorable fit with the experimental parameters. The determination experiment resulted in a methane yield of 290 mL g-1 VS, 88.0% higher than that of untreated rice straw. Thus, H2O2 pretreatment of rice straw can be used to improve methane yields during biogas production.
