为深入探讨氮沉降影响草原植物金属养分吸收及其与土壤养分的耦合关系,以内蒙古典型草原4种主要物种为研究对象,设置0、5、10、15 g N/(m^(2)·yr)4个氮添加处理,分析不同施氮量对草原物种及群落水平植物叶片盐基、微量元素含量和...为深入探讨氮沉降影响草原植物金属养分吸收及其与土壤养分的耦合关系,以内蒙古典型草原4种主要物种为研究对象,设置0、5、10、15 g N/(m^(2)·yr)4个氮添加处理,分析不同施氮量对草原物种及群落水平植物叶片盐基、微量元素含量和储量的影响。结果表明:(1)杂类草比禾本科植物具有更高的养分浓度;(2)不同金属养分对氮沉降的响应具有高度的物种特异性;植物群落叶片盐基元素含量对氮添加无显著响应且与土壤盐基离子相关性较低;随氮添加量的增加,叶片中Mn、Cu含量增加,但Fe含量降低,草原植物微量元素失衡严重主要受土壤微量养分有效性和元素拮抗作用的影响;(3)植物金属元素地上储量的饱和阈值出现在10 g N/(m^(2)·yr);优势物种地上生物量对氮添加的非线性响应是驱动植物元素地上储量变化的主要机制。展开更多
Diamond film have been synthesized by dc plasma chemical vapour deposition(CVD)from a gaseous mixture of acetone and hydrogen gases with a growth rate of 220μm/h.The films obtained have good crystallinity that are ch...Diamond film have been synthesized by dc plasma chemical vapour deposition(CVD)from a gaseous mixture of acetone and hydrogen gases with a growth rate of 220μm/h.The films obtained have good crystallinity that are chaxacte-ized by Raman spectrometry,scanning electron microscopy and x-ray diffraction.X-ray photoelectron spectroscopy analysis have confirmed that diamond nucleation and growth are on SiC rather than on clean Si.The mechanism of high rate growth diamond film have been discussed too.展开更多
To meet the need of teaching swimming in deep pool, the study designed a set of teaching method, by which beginners cou1d learn breast stroke and swim up to 5O meters in deep water. The newly designed method put empha...To meet the need of teaching swimming in deep pool, the study designed a set of teaching method, by which beginners cou1d learn breast stroke and swim up to 5O meters in deep water. The newly designed method put emphasis on intensified technical drill on land and aJso included simplified procedure of getting familar with the characteristics of water, improved sequence of coordination, use of floats as aids, and adoptation of collective teaching form. The method has been proved to be safe, more effective with less teaching hours and uniform progreess, and consistent to the mental and physiological characteristics of beginners.展开更多
文摘为深入探讨氮沉降影响草原植物金属养分吸收及其与土壤养分的耦合关系,以内蒙古典型草原4种主要物种为研究对象,设置0、5、10、15 g N/(m^(2)·yr)4个氮添加处理,分析不同施氮量对草原物种及群落水平植物叶片盐基、微量元素含量和储量的影响。结果表明:(1)杂类草比禾本科植物具有更高的养分浓度;(2)不同金属养分对氮沉降的响应具有高度的物种特异性;植物群落叶片盐基元素含量对氮添加无显著响应且与土壤盐基离子相关性较低;随氮添加量的增加,叶片中Mn、Cu含量增加,但Fe含量降低,草原植物微量元素失衡严重主要受土壤微量养分有效性和元素拮抗作用的影响;(3)植物金属元素地上储量的饱和阈值出现在10 g N/(m^(2)·yr);优势物种地上生物量对氮添加的非线性响应是驱动植物元素地上储量变化的主要机制。
文摘Diamond film have been synthesized by dc plasma chemical vapour deposition(CVD)from a gaseous mixture of acetone and hydrogen gases with a growth rate of 220μm/h.The films obtained have good crystallinity that are chaxacte-ized by Raman spectrometry,scanning electron microscopy and x-ray diffraction.X-ray photoelectron spectroscopy analysis have confirmed that diamond nucleation and growth are on SiC rather than on clean Si.The mechanism of high rate growth diamond film have been discussed too.
文摘To meet the need of teaching swimming in deep pool, the study designed a set of teaching method, by which beginners cou1d learn breast stroke and swim up to 5O meters in deep water. The newly designed method put emphasis on intensified technical drill on land and aJso included simplified procedure of getting familar with the characteristics of water, improved sequence of coordination, use of floats as aids, and adoptation of collective teaching form. The method has been proved to be safe, more effective with less teaching hours and uniform progreess, and consistent to the mental and physiological characteristics of beginners.
