FACING Taiwan Island,the legendary birthplace of sea goddess Mazu, Meizhou Bay extends along the coast of southeast China's Fujian Province. Surrounded on three sides by verdant hills,the Bay's mouth opens to ...FACING Taiwan Island,the legendary birthplace of sea goddess Mazu, Meizhou Bay extends along the coast of southeast China's Fujian Province. Surrounded on three sides by verdant hills,the Bay's mouth opens to the southeast,and forms a natural harbor for local boats to take shelter from the wind.展开更多
黑土作为吉林中部平原粮食主产区主要土壤类型,其质量的优劣直接影响区域生态安全和农业可持续发展。该研究以吉林省典型黑土耕层土壤作为研究对象,采集1401个土壤样本,测定8项土壤理化指标及玉米产量。采用最小数据集法筛选评价指标,...黑土作为吉林中部平原粮食主产区主要土壤类型,其质量的优劣直接影响区域生态安全和农业可持续发展。该研究以吉林省典型黑土耕层土壤作为研究对象,采集1401个土壤样本,测定8项土壤理化指标及玉米产量。采用最小数据集法筛选评价指标,对于黑土耕层土壤进行质量评价,并综合土壤质量指数和产量提出评价指标的适宜范围。结果表明:吉林省黑土耕层土壤质量评价最小数据集由耕层容重、有机质、速效磷、pH构成,由全量数据集(Total Data Set,TDS)、重要数据集(Important Data Set,IDS)和最小数据集(Minimum Data Set,MDS)分别计算的土壤质量指数之间存在显著正相关关系,R^(2)分别为0.716、0.771,表明MDS可以替代TDS对黑土耕层土壤质量进行评价。黑土玉米种植区耕层土壤质量指数分布在0.22~0.75之间,均值为0.53,呈现东部高西部低的趋势。土壤质量指数随产量先增加后降低。黑土耕层保持较高土壤质量及产量的评价指标适宜范围分别为:容重为1.23~1.43 g/cm^(3),酸碱度(pH值)为4.74~6.96,有机质为33.14~35.81 g/kg,有效磷为122.46~136.06 mg/kg。该研究结果可为吉林省黑土耕层土壤质量诊断、提高黑土肥力及选择适合农田管理措施提供理论及参数支撑。展开更多
该文采用非变性电喷雾质谱法(Native electrospray ionization mass spectrometry,ESI-MS)与分子对接模拟计算(MD)分别研究了1种溴代阻燃剂和2种羟基化代谢物,即3,5,3',5'-四溴-4,4'-二羟基基二苯砜(TBS)、4-羟基-2,2',...该文采用非变性电喷雾质谱法(Native electrospray ionization mass spectrometry,ESI-MS)与分子对接模拟计算(MD)分别研究了1种溴代阻燃剂和2种羟基化代谢物,即3,5,3',5'-四溴-4,4'-二羟基基二苯砜(TBS)、4-羟基-2,2',3,4',5,5',6-八溴联苯醚(4-OH-BDE-187)、6-羟基-2,2',3,4,4',5,5'-八溴联苯醚(6-OH-BDE-180)与甲状腺素运载蛋白(TTR)的相互作用情况。ESI-MS结果表明,在37℃及生理pH值条件下的醋酸铵缓冲溶液中,TBS与TTR蛋白可形成稳定的化学计量比为1∶1的复合物,4-OH-BDE-187、6-OH-BDE-180可与TTR蛋白分别形成稳定的化学计量比为1∶1和2∶1的复合物。通过分子对接模拟计算方法推测了上述3种配体与TTR可能的结合模型,发现3种配体与TTR的结合位点位于ASP-74残基附近。研究结果可为进一步了解溴代阻燃剂及其羟基化代谢产物体内的生物过程及毒性机制提供实验基础。展开更多
We investigate the characteristics of AlGaN/GaN metal-insulator-semiconductor high-electron-mobility transistors (MIS-HEMTs) with a NbAlO/Al_(2)O_(3) lamination dielectric deposited by atomic layer deposition (ALD) as...We investigate the characteristics of AlGaN/GaN metal-insulator-semiconductor high-electron-mobility transistors (MIS-HEMTs) with a NbAlO/Al_(2)O_(3) lamination dielectric deposited by atomic layer deposition (ALD) as the gate insulator.A large gate voltage swing (GVS) of 3.96 V and a high breakdown voltage of-150 V for the MIS-HEMT were obtained.We present the gate leakage current mechanisms and analyze the reason for the reduction of the leakage current.Compared with traditional HEMTs,the maximum drain current is improved to 960mA/mm,indicating that NbAlO layers could reduce the surface-related depletion of the channel layer and increase the sheet carrier concentration.In addition,the maximum oscillation frequency of 38.8 GHz shows that the NbAlO high-k dielectric can be considered as a potential gate oxide comparable with other dielectric insulators.展开更多
文摘FACING Taiwan Island,the legendary birthplace of sea goddess Mazu, Meizhou Bay extends along the coast of southeast China's Fujian Province. Surrounded on three sides by verdant hills,the Bay's mouth opens to the southeast,and forms a natural harbor for local boats to take shelter from the wind.
文摘黑土作为吉林中部平原粮食主产区主要土壤类型,其质量的优劣直接影响区域生态安全和农业可持续发展。该研究以吉林省典型黑土耕层土壤作为研究对象,采集1401个土壤样本,测定8项土壤理化指标及玉米产量。采用最小数据集法筛选评价指标,对于黑土耕层土壤进行质量评价,并综合土壤质量指数和产量提出评价指标的适宜范围。结果表明:吉林省黑土耕层土壤质量评价最小数据集由耕层容重、有机质、速效磷、pH构成,由全量数据集(Total Data Set,TDS)、重要数据集(Important Data Set,IDS)和最小数据集(Minimum Data Set,MDS)分别计算的土壤质量指数之间存在显著正相关关系,R^(2)分别为0.716、0.771,表明MDS可以替代TDS对黑土耕层土壤质量进行评价。黑土玉米种植区耕层土壤质量指数分布在0.22~0.75之间,均值为0.53,呈现东部高西部低的趋势。土壤质量指数随产量先增加后降低。黑土耕层保持较高土壤质量及产量的评价指标适宜范围分别为:容重为1.23~1.43 g/cm^(3),酸碱度(pH值)为4.74~6.96,有机质为33.14~35.81 g/kg,有效磷为122.46~136.06 mg/kg。该研究结果可为吉林省黑土耕层土壤质量诊断、提高黑土肥力及选择适合农田管理措施提供理论及参数支撑。
文摘该文采用非变性电喷雾质谱法(Native electrospray ionization mass spectrometry,ESI-MS)与分子对接模拟计算(MD)分别研究了1种溴代阻燃剂和2种羟基化代谢物,即3,5,3',5'-四溴-4,4'-二羟基基二苯砜(TBS)、4-羟基-2,2',3,4',5,5',6-八溴联苯醚(4-OH-BDE-187)、6-羟基-2,2',3,4,4',5,5'-八溴联苯醚(6-OH-BDE-180)与甲状腺素运载蛋白(TTR)的相互作用情况。ESI-MS结果表明,在37℃及生理pH值条件下的醋酸铵缓冲溶液中,TBS与TTR蛋白可形成稳定的化学计量比为1∶1的复合物,4-OH-BDE-187、6-OH-BDE-180可与TTR蛋白分别形成稳定的化学计量比为1∶1和2∶1的复合物。通过分子对接模拟计算方法推测了上述3种配体与TTR可能的结合模型,发现3种配体与TTR的结合位点位于ASP-74残基附近。研究结果可为进一步了解溴代阻燃剂及其羟基化代谢产物体内的生物过程及毒性机制提供实验基础。
基金Supported by the State Key Program and Major Program of the National Natural Science Foundation of China under Grant Nos 60736033 and 60890191the Doctoral Scientific Research Fund of Beijing University of Technology(No X0002013201101)。
文摘We investigate the characteristics of AlGaN/GaN metal-insulator-semiconductor high-electron-mobility transistors (MIS-HEMTs) with a NbAlO/Al_(2)O_(3) lamination dielectric deposited by atomic layer deposition (ALD) as the gate insulator.A large gate voltage swing (GVS) of 3.96 V and a high breakdown voltage of-150 V for the MIS-HEMT were obtained.We present the gate leakage current mechanisms and analyze the reason for the reduction of the leakage current.Compared with traditional HEMTs,the maximum drain current is improved to 960mA/mm,indicating that NbAlO layers could reduce the surface-related depletion of the channel layer and increase the sheet carrier concentration.In addition,the maximum oscillation frequency of 38.8 GHz shows that the NbAlO high-k dielectric can be considered as a potential gate oxide comparable with other dielectric insulators.
