In addition to light and water, CO2 and mineral elements are required for plant growth and development. Among these factors, nitrogen is critical, since it is needed to synthesize amino acids, which are the building e...In addition to light and water, CO2 and mineral elements are required for plant growth and development. Among these factors, nitrogen is critical, since it is needed to synthesize amino acids, which are the building elements of protein, nucleotides, chlorophyll, and numerous other metabolites and cellular components. Therefore, nitrogen is required by plants in higher quantities and this investment in nitrogen supports the use of CO2, water, and inorganic nitrogen to produce sugars, organic acids, and amino acids, the basic building blocks of biomass accumulation. This system is maintained by complex metabolic machinery, which is regulated at different levels according to environmental factors such as light, CO2, and nutrient availability. Plants integrate these signals via a signaling network, which involves metabolites as well as nutrient-sensing proteins. Due to its importance, much research effort has been expended to understand how carbon and nitrogen metabolism are integrated and regulated according to the rates of photosynthesis, photorespiration, and respiration. Thus, in this article, we both discuss recent advances in carbon/nitrogen metabolisms as well as sensing and signaling systems in illuminated leaves of C3-plants and provide a perspective of the type of experiments that are now required in order to take our understanding to a higher level.展开更多
For reasons of simplicity, the most commonly used hydrological models are based on the Soil Conservation Service Curve Number （SCS-CN） model, which is probably a good choice for the estimation of runoff on the Loess...For reasons of simplicity, the most commonly used hydrological models are based on the Soil Conservation Service Curve Number （SCS-CN） model, which is probably a good choice for the estimation of runoff on the Loess Plateau of China; however, the high spatial heterogeneity, mainly caused by a fragmented landform and variations in soil type, may limit its applicability to this region. Therefore, applicability of the SCS-CN model to a small watershed, Liudaogou on the plateau, was evaluated and the most appropriate initial abstraction ratio （I~/S） value in the model was quantified by the inverse method. The results showed that the standard SCS-CN model was applicable to the estimation of runoff in the Liudaogou watershed and the model performance was acceptable according to the values of relative error and Nash-Sutcliffe efficiency. The most appropriate Ia/S value for the watershed was 0.22 because with this modified Ia/S value, the model performance was slightly improved. The model performance was not sensitive to the modification of the Ia/S value when one heavy rainfall event （50.1 mm） was not considered, which implied that the model, using a standard Ia/S value, can be recommended for the Liudaogou watershed because single rainfall events exceeding 50 mm seldom occurred in that region. The runoff amount predicted for the Liudaogou watershed by the SCS-CN model, using the modified Ia/S value, increased gradually with increasing rainfall when rainfall values were lower than 50 mm, whereas the predicted amount increased rapidly when the rainfall exceeded 50 mm. These findings may be helpful in solving the problem of serious soil and water loss on the Loess Plateau of China.展开更多
目的探讨有氧运动干预对心血管神经症(CN)的影响.方法将60例CN患者随机分为二组,即药物治疗组和运动治疗组各30例.药物治疗组给予谷维素和倍他乐克治疗,运动组在药物治疗基础上加用运动治疗,疗程3个月.两组治疗前均进行运动平板心电图检...目的探讨有氧运动干预对心血管神经症(CN)的影响.方法将60例CN患者随机分为二组,即药物治疗组和运动治疗组各30例.药物治疗组给予谷维素和倍他乐克治疗,运动组在药物治疗基础上加用运动治疗,疗程3个月.两组治疗前均进行运动平板心电图检查,运动组根据测试结果的最大运动量的70%～80%制定运动量进行有氧运动.两组治疗前后采用症状自评量表(SCL-90)进行评分.结果 1.CN患者运动能力与正常人比较无统计学意义(最大心率161±10.1 vs 160.9±10.7,最大代谢当量10.4±2.1 vs 10.0±1.7,P均＞0.05);2.干预后运动组SCL-90各项评分明显低于药物治疗组(总分147.9±28.9 vs 186.0±43.7,总均分1.6±0.3 vs 2.1±0.5,阳性分91.8±42.7 vs 142.6±59.2,阳性均分2.6±0.4 vs 3.1±0.3,P均＜0.01),以躯体表现、抑郁、焦虑、恐怖尤为明显(分别为1.9±0.6 vs 2.2±0.6,1.8±0.6 vs 2.2±0.8,1.7±0.4 vs 2.6±0.8,1.4±0.3 vs 1.7±0.7,P均＜0.01).结论运动治疗心血管神经症安全、有效,值得临床推广.展开更多
文摘In addition to light and water, CO2 and mineral elements are required for plant growth and development. Among these factors, nitrogen is critical, since it is needed to synthesize amino acids, which are the building elements of protein, nucleotides, chlorophyll, and numerous other metabolites and cellular components. Therefore, nitrogen is required by plants in higher quantities and this investment in nitrogen supports the use of CO2, water, and inorganic nitrogen to produce sugars, organic acids, and amino acids, the basic building blocks of biomass accumulation. This system is maintained by complex metabolic machinery, which is regulated at different levels according to environmental factors such as light, CO2, and nutrient availability. Plants integrate these signals via a signaling network, which involves metabolites as well as nutrient-sensing proteins. Due to its importance, much research effort has been expended to understand how carbon and nitrogen metabolism are integrated and regulated according to the rates of photosynthesis, photorespiration, and respiration. Thus, in this article, we both discuss recent advances in carbon/nitrogen metabolisms as well as sensing and signaling systems in illuminated leaves of C3-plants and provide a perspective of the type of experiments that are now required in order to take our understanding to a higher level.
基金Supported by the National Natural Science Foundation of China (No.41001156)the Beijing Novel Program, China (No.2009B25)+1 种基金the Beijing Municipal Natural Science Foundation, China (No.8102015)the Open Fund of the State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau of China (No.10501-295)
文摘For reasons of simplicity, the most commonly used hydrological models are based on the Soil Conservation Service Curve Number （SCS-CN） model, which is probably a good choice for the estimation of runoff on the Loess Plateau of China; however, the high spatial heterogeneity, mainly caused by a fragmented landform and variations in soil type, may limit its applicability to this region. Therefore, applicability of the SCS-CN model to a small watershed, Liudaogou on the plateau, was evaluated and the most appropriate initial abstraction ratio （I~/S） value in the model was quantified by the inverse method. The results showed that the standard SCS-CN model was applicable to the estimation of runoff in the Liudaogou watershed and the model performance was acceptable according to the values of relative error and Nash-Sutcliffe efficiency. The most appropriate Ia/S value for the watershed was 0.22 because with this modified Ia/S value, the model performance was slightly improved. The model performance was not sensitive to the modification of the Ia/S value when one heavy rainfall event （50.1 mm） was not considered, which implied that the model, using a standard Ia/S value, can be recommended for the Liudaogou watershed because single rainfall events exceeding 50 mm seldom occurred in that region. The runoff amount predicted for the Liudaogou watershed by the SCS-CN model, using the modified Ia/S value, increased gradually with increasing rainfall when rainfall values were lower than 50 mm, whereas the predicted amount increased rapidly when the rainfall exceeded 50 mm. These findings may be helpful in solving the problem of serious soil and water loss on the Loess Plateau of China.
文摘目的探讨有氧运动干预对心血管神经症(CN)的影响.方法将60例CN患者随机分为二组,即药物治疗组和运动治疗组各30例.药物治疗组给予谷维素和倍他乐克治疗,运动组在药物治疗基础上加用运动治疗,疗程3个月.两组治疗前均进行运动平板心电图检查,运动组根据测试结果的最大运动量的70%～80%制定运动量进行有氧运动.两组治疗前后采用症状自评量表(SCL-90)进行评分.结果 1.CN患者运动能力与正常人比较无统计学意义(最大心率161±10.1 vs 160.9±10.7,最大代谢当量10.4±2.1 vs 10.0±1.7,P均＞0.05);2.干预后运动组SCL-90各项评分明显低于药物治疗组(总分147.9±28.9 vs 186.0±43.7,总均分1.6±0.3 vs 2.1±0.5,阳性分91.8±42.7 vs 142.6±59.2,阳性均分2.6±0.4 vs 3.1±0.3,P均＜0.01),以躯体表现、抑郁、焦虑、恐怖尤为明显(分别为1.9±0.6 vs 2.2±0.6,1.8±0.6 vs 2.2±0.8,1.7±0.4 vs 2.6±0.8,1.4±0.3 vs 1.7±0.7,P均＜0.01).结论运动治疗心血管神经症安全、有效,值得临床推广.
