【目的】土壤酸化是耕地质量退化的突出问题,研究主要农作物产量对土壤pH的响应及其影响因素,为土壤酸化防治提供理论依据。【方法】通过“中国知网”、“Web of Science”数据库,分别以玉米(maize)、水稻(rice)、小麦(wheat)、大豆(soy...【目的】土壤酸化是耕地质量退化的突出问题,研究主要农作物产量对土壤pH的响应及其影响因素,为土壤酸化防治提供理论依据。【方法】通过“中国知网”、“Web of Science”数据库,分别以玉米(maize)、水稻(rice)、小麦(wheat)、大豆(soybean)、土壤pH(soil pH)、作物产量(yield)为关键词,获取1980—2020年已公开发表的文献数据。基于国内外大田试验,分析了玉米、水稻、小麦、大豆产量与土壤pH的关系,运用Sigmoid函数计算作物酸害阈值,结合皮尔逊相关性分析与偏相关分析,明确作物酸害阈值的主要影响因素。【结果】1)4种作物产量伴随土壤pH降低均呈“S”型降低趋势;玉米、大豆、小麦和水稻产量95%的酸害阈值分别为pH 5.87、5.34、5.32和4.21。2)作物相对产量与交换性铝呈显著负相关,与土壤pH、交换性钙、钙铝比、有机质、有效磷、化学氮肥施用量呈显著正相关。当土壤pH大于酸害阈值时,作物产量与有机质、有效磷呈显著正相关,当土壤pH小于酸害阈值时,作物产量与土壤pH、交换性钙、钙铝比呈显著正相关,与交换性铝呈显著负相关。3)偏相关分析表明,剔除有机质影响后,相对产量与pH的相关系数升高0.207,交换性铝与相对产量的相关系数升高0.072;剔除有效磷影响后,相对产量与pH的相关系数升高0.085,交换性铝与相对产量的相关系数升高0.147;剔除施氮量影响后,相对产量与pH的相关系数升高0.026,交换性铝与相对产量的相关系数降低0.009。有效磷、有机质和化学氮肥施用量是影响作物产量对土壤pH响应的关键因素。【结论】当土壤pH低于酸害阈值时,较高的有效磷和有机质含量可降低土壤pH对作物产量的不利影响,即有效磷和有机质含量越高,作物酸害越轻。展开更多
Aims: To investigate whether intravesical lower pH induces a micturition threshold reflex change of anaesthetized rats. Methods: Thirteen female rats, anaesthetized by a-chloralose and paralyzed by pancurone bromide w...Aims: To investigate whether intravesical lower pH induces a micturition threshold reflex change of anaesthetized rats. Methods: Thirteen female rats, anaesthetized by a-chloralose and paralyzed by pancurone bromide were used for the experiments. The micturition threshold volume was determined by repeated cystometry. Simultaneously bladder afferent activities in four and efferent activities in seven rats were recorded from the exposed pelvic nerve to the bladder. Results: Cystometry with acidic saline at pH 3 and 4 induced a significant decrease in micturition threshold volume. The mean value of these groups of test showed that bladder compliance, micturition threshold pressure and maximal micturition contraction pressure were decreased significantly comparing with the controls. There were no changes in all other parameters recorded from afferent and efferent, e.g. afferent threshold volume, afferent or efferent activity at the micturition threshold and their peak activity at the micturition contraction. Conclusions: Acidic solution provoked sensitivity but reduced the force of the contractility to the urinary bladder. The effect was presented without a detectable change in the firing properties of bladder Ad mechanoreceptor afferents. It is proposed that proton sensitive bladder receptors with unmyelinated afferent were stimulated by the acidic solution and that the micturition reflex was facilitated by afferent inflow from such receptors. The findings were clinically important in choosing the medium for urodynamic examination.展开更多
Research into new pH sensors fabricated by the standard CMOS process is currently a hot topic. The new pH sensing multi-floating gate field effect transistor is found to have a very large threshold voltage, which is d...Research into new pH sensors fabricated by the standard CMOS process is currently a hot topic. The new pH sensing multi-floating gate field effect transistor is found to have a very large threshold voltage, which is different from the normal ion-sensitive field effect transistor. After analyzing all the interface layers of the structure, a new sensitive model based on the Gauss theorem and the charge neutrality principle is created in this paper. According to the model, the charge trapped on the multi-floating gate during the process and the thickness of the sensitive layer are the main causes of the large threshold voltage. From this model, it is also found that removing the charge on the multi-floating gate is an effective way to decrease the threshold voltage. The test results for three different standard pH buffer solutions show the correctness of the model and point the way to solve the large threshold problem.展开更多
文摘【目的】土壤酸化是耕地质量退化的突出问题,研究主要农作物产量对土壤pH的响应及其影响因素,为土壤酸化防治提供理论依据。【方法】通过“中国知网”、“Web of Science”数据库,分别以玉米(maize)、水稻(rice)、小麦(wheat)、大豆(soybean)、土壤pH(soil pH)、作物产量(yield)为关键词,获取1980—2020年已公开发表的文献数据。基于国内外大田试验,分析了玉米、水稻、小麦、大豆产量与土壤pH的关系,运用Sigmoid函数计算作物酸害阈值,结合皮尔逊相关性分析与偏相关分析,明确作物酸害阈值的主要影响因素。【结果】1)4种作物产量伴随土壤pH降低均呈“S”型降低趋势;玉米、大豆、小麦和水稻产量95%的酸害阈值分别为pH 5.87、5.34、5.32和4.21。2)作物相对产量与交换性铝呈显著负相关,与土壤pH、交换性钙、钙铝比、有机质、有效磷、化学氮肥施用量呈显著正相关。当土壤pH大于酸害阈值时,作物产量与有机质、有效磷呈显著正相关,当土壤pH小于酸害阈值时,作物产量与土壤pH、交换性钙、钙铝比呈显著正相关,与交换性铝呈显著负相关。3)偏相关分析表明,剔除有机质影响后,相对产量与pH的相关系数升高0.207,交换性铝与相对产量的相关系数升高0.072;剔除有效磷影响后,相对产量与pH的相关系数升高0.085,交换性铝与相对产量的相关系数升高0.147;剔除施氮量影响后,相对产量与pH的相关系数升高0.026,交换性铝与相对产量的相关系数降低0.009。有效磷、有机质和化学氮肥施用量是影响作物产量对土壤pH响应的关键因素。【结论】当土壤pH低于酸害阈值时,较高的有效磷和有机质含量可降低土壤pH对作物产量的不利影响,即有效磷和有机质含量越高,作物酸害越轻。
文摘Aims: To investigate whether intravesical lower pH induces a micturition threshold reflex change of anaesthetized rats. Methods: Thirteen female rats, anaesthetized by a-chloralose and paralyzed by pancurone bromide were used for the experiments. The micturition threshold volume was determined by repeated cystometry. Simultaneously bladder afferent activities in four and efferent activities in seven rats were recorded from the exposed pelvic nerve to the bladder. Results: Cystometry with acidic saline at pH 3 and 4 induced a significant decrease in micturition threshold volume. The mean value of these groups of test showed that bladder compliance, micturition threshold pressure and maximal micturition contraction pressure were decreased significantly comparing with the controls. There were no changes in all other parameters recorded from afferent and efferent, e.g. afferent threshold volume, afferent or efferent activity at the micturition threshold and their peak activity at the micturition contraction. Conclusions: Acidic solution provoked sensitivity but reduced the force of the contractility to the urinary bladder. The effect was presented without a detectable change in the firing properties of bladder Ad mechanoreceptor afferents. It is proposed that proton sensitive bladder receptors with unmyelinated afferent were stimulated by the acidic solution and that the micturition reflex was facilitated by afferent inflow from such receptors. The findings were clinically important in choosing the medium for urodynamic examination.
基金Project supported by the National Natural Science Foundation of China (No.60576050)
文摘Research into new pH sensors fabricated by the standard CMOS process is currently a hot topic. The new pH sensing multi-floating gate field effect transistor is found to have a very large threshold voltage, which is different from the normal ion-sensitive field effect transistor. After analyzing all the interface layers of the structure, a new sensitive model based on the Gauss theorem and the charge neutrality principle is created in this paper. According to the model, the charge trapped on the multi-floating gate during the process and the thickness of the sensitive layer are the main causes of the large threshold voltage. From this model, it is also found that removing the charge on the multi-floating gate is an effective way to decrease the threshold voltage. The test results for three different standard pH buffer solutions show the correctness of the model and point the way to solve the large threshold problem.
