The dynamics of chlorophyll content, leaf area and photosynthesis of cucumber seedlings were studied under sole stress of two low temperatures and low light intensity as well as combined stresses of low light intensit...The dynamics of chlorophyll content, leaf area and photosynthesis of cucumber seedlings were studied under sole stress of two low temperatures and low light intensity as well as combined stresses of low light intensity and the two low temperatures. The results showed that low light intensity reduced sensitivity of cucumber to low temperature and improved chlorophyll content, leaf area and chlorophyll fluorescence quantum yield. The photosynthesis rate was reduced under low light intensity. The intensity of light played the leading role in growth of cucumber under the low temperature condition, while the low temperature played the leading role under the critical low temperature condition. There were differences in reaction to light and temperature among different varieties. The tolerance to low temperature and low light intensity was not always synergetic for the same cucumber variety.展开更多
探究不同施磷水平对夏花生产量、品质及磷素积累动态、光温生理特性和根系形态影响效应,为花生高效科学施用磷肥提供理论支持。2021—2022年在河南省温县布置磷肥用量田间试验,供试品种为“豫花22”,设P2O50、30、60、90、120 kg hm^(-...探究不同施磷水平对夏花生产量、品质及磷素积累动态、光温生理特性和根系形态影响效应,为花生高效科学施用磷肥提供理论支持。2021—2022年在河南省温县布置磷肥用量田间试验,供试品种为“豫花22”,设P2O50、30、60、90、120 kg hm^(-2)5个磷肥用量处理。于成熟期测定夏花生荚果产量和品质指标,并分别于苗期、花针期、结荚期、饱果期测定叶片SPAD值、冠层光合有效辐射和冠层温度,采集植株样品分析植株磷素积累量和根系形态。结果表明,随施磷量增加,2年夏花生荚果产量均呈“线性+平台”趋势变化,适宜施磷量分别为94 kg hm^(-2)和95 kg hm^(-2),施磷处理2年平均增产23.68%。成熟期籽粒粗蛋白、含油量和氨基酸含量均随施磷量增加呈“先升高后趋于稳定”趋势变化。与不施磷相比,施磷90 kg hm^(-2)时籽粒粗蛋白、含油量和氨基酸含量2年度平均增幅分别为11.06%、3.89%和11.58%,效果显著。通过Logistic方程对夏花生磷素积累量进行非线性回归拟合,得出施磷处理通过提高夏花生磷素最大积累速率(V_(m))和平均积累速率(V),延长快速积累期(Δt)与活跃积累期(T_(aas)),进而提高磷素最大积累量(Y_(m));适量施磷提高各部位磷素吸收积累量,促进磷素向荚果中分配。夏花生冠层最高温、最低温与平均温均随施磷量的增加显著降低;叶片SPAD值与冠层光合有效辐射量(APAR)和分量(FPAR)在施磷90 kg hm^(-2)时显著增加;施磷处理夏花生耕层总根长、根平均直径、根体积和根表面积分别平均增加48.50%、16.25%、37.80%和21.88%。磷肥利用率和偏生产力随施磷量增加逐渐降低,农学效率呈先升高后降低的变化趋势。合理施磷可显著提高夏花生产量、改善品质,促进磷素积累利用并显著改善生育期光温生理性能。本试验条件下夏花生推荐施磷量为90 kg hm^(-2)。展开更多
This paper presents seasonal regression models of demand to investigate electricity consumption characteristics. Electricity consumption in commercial areas in Japan is analyzed by using meteorological variables, name...This paper presents seasonal regression models of demand to investigate electricity consumption characteristics. Electricity consumption in commercial areas in Japan is analyzed by using meteorological variables, namely temperature and relative humidity. A dummy variable for holidays is also considered. We have developed models for two levels of period to analyze demand characteristics, that is, half year models and seasonal models. Some options for each model are calculated and validated by statistical tests to obtain better models. As results, half year and seasonal models present explicit information about how the variables affect the demand differently for each period. These specific information help in analyzing characteristics of studied commercial demand.展开更多
The factors influencing the current-voltage（I-V） characteristics of light-emitting diodes（LEDs） are investigated to reveal the connection of I-V characteristics under optical excitation and those under electrical ...The factors influencing the current-voltage（I-V） characteristics of light-emitting diodes（LEDs） are investigated to reveal the connection of I-V characteristics under optical excitation and those under electrical excitation.By inspecting the I-V curves under optical and electrical excitation at identical injection current,it has been found that the I-V curves exhibit apparent differences in voltage values.Furthermore,the differences are found to originate from the junction temperatures in diverse excitation ways.Experimental results indicate that if the thermal effect of illuminating spot is depressed to an ignorable extent by using pulsed light,the junction temperature will hardly deflect from that under optical excitation,and then the I-V characteristics under two diverse excitation ways will be the same.展开更多
基金supported by the National Natural Science Foundation of China(39830230)Beijing Natural Science Foundation(6O11002).
文摘The dynamics of chlorophyll content, leaf area and photosynthesis of cucumber seedlings were studied under sole stress of two low temperatures and low light intensity as well as combined stresses of low light intensity and the two low temperatures. The results showed that low light intensity reduced sensitivity of cucumber to low temperature and improved chlorophyll content, leaf area and chlorophyll fluorescence quantum yield. The photosynthesis rate was reduced under low light intensity. The intensity of light played the leading role in growth of cucumber under the low temperature condition, while the low temperature played the leading role under the critical low temperature condition. There were differences in reaction to light and temperature among different varieties. The tolerance to low temperature and low light intensity was not always synergetic for the same cucumber variety.
文摘探究不同施磷水平对夏花生产量、品质及磷素积累动态、光温生理特性和根系形态影响效应,为花生高效科学施用磷肥提供理论支持。2021—2022年在河南省温县布置磷肥用量田间试验,供试品种为“豫花22”,设P2O50、30、60、90、120 kg hm^(-2)5个磷肥用量处理。于成熟期测定夏花生荚果产量和品质指标,并分别于苗期、花针期、结荚期、饱果期测定叶片SPAD值、冠层光合有效辐射和冠层温度,采集植株样品分析植株磷素积累量和根系形态。结果表明,随施磷量增加,2年夏花生荚果产量均呈“线性+平台”趋势变化,适宜施磷量分别为94 kg hm^(-2)和95 kg hm^(-2),施磷处理2年平均增产23.68%。成熟期籽粒粗蛋白、含油量和氨基酸含量均随施磷量增加呈“先升高后趋于稳定”趋势变化。与不施磷相比,施磷90 kg hm^(-2)时籽粒粗蛋白、含油量和氨基酸含量2年度平均增幅分别为11.06%、3.89%和11.58%,效果显著。通过Logistic方程对夏花生磷素积累量进行非线性回归拟合,得出施磷处理通过提高夏花生磷素最大积累速率(V_(m))和平均积累速率(V),延长快速积累期(Δt)与活跃积累期(T_(aas)),进而提高磷素最大积累量(Y_(m));适量施磷提高各部位磷素吸收积累量,促进磷素向荚果中分配。夏花生冠层最高温、最低温与平均温均随施磷量的增加显著降低;叶片SPAD值与冠层光合有效辐射量(APAR)和分量(FPAR)在施磷90 kg hm^(-2)时显著增加;施磷处理夏花生耕层总根长、根平均直径、根体积和根表面积分别平均增加48.50%、16.25%、37.80%和21.88%。磷肥利用率和偏生产力随施磷量增加逐渐降低,农学效率呈先升高后降低的变化趋势。合理施磷可显著提高夏花生产量、改善品质,促进磷素积累利用并显著改善生育期光温生理性能。本试验条件下夏花生推荐施磷量为90 kg hm^(-2)。
文摘This paper presents seasonal regression models of demand to investigate electricity consumption characteristics. Electricity consumption in commercial areas in Japan is analyzed by using meteorological variables, namely temperature and relative humidity. A dummy variable for holidays is also considered. We have developed models for two levels of period to analyze demand characteristics, that is, half year models and seasonal models. Some options for each model are calculated and validated by statistical tests to obtain better models. As results, half year and seasonal models present explicit information about how the variables affect the demand differently for each period. These specific information help in analyzing characteristics of studied commercial demand.
基金Project supported by the National Natural Science Foundation of China(No.61006053)the National Science Foundation ofCQ CSTC (No.CSTC 2008BB3156)
文摘The factors influencing the current-voltage（I-V） characteristics of light-emitting diodes（LEDs） are investigated to reveal the connection of I-V characteristics under optical excitation and those under electrical excitation.By inspecting the I-V curves under optical and electrical excitation at identical injection current,it has been found that the I-V curves exhibit apparent differences in voltage values.Furthermore,the differences are found to originate from the junction temperatures in diverse excitation ways.Experimental results indicate that if the thermal effect of illuminating spot is depressed to an ignorable extent by using pulsed light,the junction temperature will hardly deflect from that under optical excitation,and then the I-V characteristics under two diverse excitation ways will be the same.
