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991.
992.
功率因数是供电系统的一项重要技术经济指标,用电设备在消耗有用功率的同时,还有大量的无用功率由电源送往负荷,功率因素反映的是用电设备在消耗一定的有功功率的同时所需要的无功功率。 相似文献
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Fusheng Ma Shaozhong Kang Fusheng Li Jianhua Zhang Taisheng Du Xiaotao Hu Mixia Wang 《Agricultural Water Management》2007,90(3):190-196
The effects of water deficit in different fruit growth stages on the variation of stem sap flux of 6-year old greenhouse-grown pear-jujube trees were investigated. Treatments included sufficient water supply during the whole fruit-growing period (T1), mild water deficit during the flowering–fruit setting stage (T2), moderate water deficit during the fruit rapid growth stage (T3) and severe water deficit during the fruit maturing stage (T4). Results showed that significant compensation effect on stem sap flux after re-watering was observed in T2, but not in T3 and T4 stages. At the end of rapid growth stage, the diurnal variation of stomatal conductance generally had a similar trend as that of stem sap flux, but with a distinct midday depression from 12:00 to 14:00 p.m. In addition, a linear relationship between the relative available soil water content (RAWC) and the ratio of daily stem sap flux to that of sufficient water treatment was observed (R2 = 0.4489). 相似文献
997.
Tall fescue is an important cool season turfgrass. Summer high temperature negatively affects the performance of tall fescue in transitional and warm climate zones. To identify heat tolerant material, 120 tall fescue accessions from different regions of the world were collected and subjected to high temperature under the greenhouse and the growth chamber conditions. Average temperature was 43 °C in the greenhouse trial. Meanwhile, in the growth chamber trial there were 38/30 °C (day/night) and 25/16 °C for heat stress and control, respectively. Leaf water content, leaf dry weight, leaf fresh weight, growth rate (GR), turf quality (TQ), survival rate (SR), chlorophyll content (Chl), evapotranspiration rate (ET) and electrolyte leakage were determined. Significant effects of accessions, duration time and heat treatment on most characteristics were observed. Wild accessions exhibited higher variations in most of the studied traits than commercial cultivars. There were differences in GR and ET with greater variation coefficients than other traits between accessions, suggesting GR and ET could be effective indices for evaluating heat tolerance of tall fescue accessions. Three principal components in growth chamber trial and two principal components in greenhouse trial were extracted. Principal component analysis indicated that common PC1, correlated with TQ, SR and Chl, was named as “turf performance component”, which explained 43.17 % and 39.24 % of genetic variations in the greenhouse trial and the growth chamber trial, respectively. PC2 that defined as “growth potential component” could explain 23.26 % of total variability in the greenhouse trial and 20.36 % in the growth chamber trial. PC3 was named as “leaf water potential component”. Two regression models (F = 0.65 × F1 + 0.35 × F2) and (F = 0.54 × F1 + 0.28 × F2 + 0.18 × F3) were formulated by factor analysis to evaluate heat tolerance of tall fescue accessions in greenhouse and growth chamber trials, respectively. Accessions from subtropical monsoon climate zone generally exhibited better heat tolerance. In contrast, accessions from East Asia showed more heat sensitive. Finally, five accessions including PI 598574, PI 608787, PI 559374, Pure Gold and PI 527504 were selected as heat tolerant accessions for future tall fescue breeding. 相似文献
998.
为提高农林废弃物的再利用率,减少农作物栽培对施肥的依赖,以农林废弃物堆肥发酵基质为栽培基质,通过采用田间对比试验的方法,对冬小麦生长进行肥效对比试验。结果表明:与普通小麦肥以及化肥相比,有机复合栽培基质对小麦增长促进作用显著,小麦平均穗长比不施肥增长8.90%,比施化肥增长5.85%,比单施普通小麦肥增长5.49%;小麦平均穗数比不施肥增长40.79%,比施化肥增长17.11%,比单施普通小麦肥增长2.63%;小麦平均单产量比不施肥增长34.78%,比施化肥增长7.89%,比单施普通小麦肥增长2.01%。该研究可为农林废弃物在作物栽培方面的合理利用提供参考。 相似文献
999.
为了区分鉴别8种根茎类作物,通过采用傅里叶变换红外光谱(FTIR)结合小波变换(WI)、主成分分析(PCA)和聚类分析(HCA)的方法,测试研究了8种根茎类作物40个样品的红外光谱。结果表明:8种样品红外图谱相似,但在1800~700 cm-1范围内,红外光谱的峰位、峰形及吸收强度差异明显。对此范围内的原始红外光谱进行连续小波和离散小波变换。提取连续小波变换的第15层系数和离散小波变换的第5尺度细节系数数据,进行主成分分析和聚类分析。连续小波和离散小波的前3个主成分的累计贡献率分别为93.12%、89.78%,主成分分析和聚类分析正确率为100%。最终结果显示:傅里叶变换红外光谱技术结合小波变换的方法可以区分鉴别不同种的根茎类作物。
相似文献1000.
Zhengong Yin Huidong Qi Qingshan Chen Zhanguo Zhang Hongwei Jiang Rongsheng Zhu Zhenbang Hu Xiaoxia Wu Candong Li Yong Zhang Chunyan Liu Guohua Hu Dawei Xin Zhaoming Qi 《Plant Breeding》2017,136(5):688-698
Plant height is closely related to seed yield of soybean. The goal of this study was to identify important loci affecting soybean plant height using meta‐analysis based on a reference physical map. Plant height related to QTLs was mapped across eight years with a RIL population by WinQTLCart v2.5. 182 QTLs related to plant height of soybean from database and our research were collected, and each QTL was projected onto the soybean physical map by software BioMercator v2.1. The confidence interval of meta‐QTL ranged from 0.09 to 5.07 Mb, and the mean phenotypic variance ranged from 4.9% to 73.0%. Furthermore, 4,259 candidate genes were located in these consensus QTLs, and 40 of them were involved in the plant growth and stem elongation and annotated as plant hormone signal transduction (pathway ID ko04075) in KEGG pathway. These results would lay a foundation for fine mapping of QTLs/genes related to plant height and marker‐assisted selection for breeding in soybean. 相似文献