Afforestation is conducive to soil carbon（C） sequestration in semi-arid regions. However, little is known about the effects of afforestation on sequestrations of total and labile soil organic carbon（SOC） fractions...Afforestation is conducive to soil carbon（C） sequestration in semi-arid regions. However, little is known about the effects of afforestation on sequestrations of total and labile soil organic carbon（SOC） fractions in semi-arid sandy lands. In the present study, we examined the effects of Caragana microphylla Lam. plantations with different ages（12-and 25-year-old） on sequestrations of total SOC as well as labile SOC fractions such as light fraction organic carbon（LFOC） and microbial biomass carbon（MBC）. The analyzed samples were taken from soil depths of 0–5 and 5–15 cm under two shrub-related scenarios： under shrubs and between shrubs with moving sand dunes as control sites in the Horqin Sandy Land of northern China. The results showed that the concentrations and storages of total SOC at soil depths of 0–5 and 5–15 cm were higher in 12-and 25-year-old C. microphylla plantations than in moving sand dunes（i.e., control sites）, with the highest value observed under shrubs in 25-year-old C. microphylla plantations. Furthermore, the concentrations and storages of LFOC and MBC showed similar patterns with those of total SOC at the same soil depth. The 12-year-old C. microphylla plantations had higher percentages of LFOC concentration to SOC concentration and MBC concentration to SOC concentration than the 25-year-old C. microphylla plantations and moving sand dunes at both soil depths. A significant positive correlation existed among SOC, LFOC, and MBC, implying that restoring the total and labile SOC fractions is possible by afforestation with C. microphylla shrubs in the Horqin Sandy Land. At soil depth of 0–15 cm, the accumulation rate of total SOC under shrubs was higher in young C. microphylla plantations（18.53 g C/（m^2·a）; 0–12 years） than in old C. microphylla plantations（16.24 g C/（m^2·a）; 12–25 years）, and the accumulation rates of LFOC and MBC under shrubs and between shrubs were also higher in young C. microphylla plantations than in old C. microphylla plantations. It can be concluded that the establishment of C. microphylla in the Horqin Sandy Land may be a good mitigation strategy for SOC sequestration in the surface soils.展开更多
为了提高窄间隙焊接的智能化水平,文中基于被动视觉传感方法,提出一种同步性好、鲁棒性强的窄间隙焊接图像坡口边缘感兴趣区域(region of interest,ROI)窗口的自适应定位方法,解决焊接过程中因坡口宽度变化带来的坡口边缘位置定位难、...为了提高窄间隙焊接的智能化水平,文中基于被动视觉传感方法,提出一种同步性好、鲁棒性强的窄间隙焊接图像坡口边缘感兴趣区域(region of interest,ROI)窗口的自适应定位方法,解决焊接过程中因坡口宽度变化带来的坡口边缘位置定位难、检测精度差的问题.通过调节坡口边缘ROI窗口水平平移量,揭示ROI窗口位置对坡口边缘图像背景与目标占比和边缘特征提取精度的影响规律,建立与电弧位置同步的坡口边缘ROI窗口生成机制,实现焊接过程中坡口边缘ROI图像的精准生成和坡口边缘的精确提取,从而提高窄间隙焊接工艺的适用性.通过变坡口焊接试验,进一步验证了所提方法在坡口边缘定位和检测中的适应性和有效性.结果表明,当坡口边缘ROI窗口顶点横坐标的水平平移量为ROI窗口宽度的50%时,检测的坡口边缘位置与平均位置差值的绝对值小于3.53μm,检测平均时间小于30 ms/帧,满足窄间隙焊接过程参数检测的精度和实时性要求.展开更多
Objective To analyze the current status of pediatric drug development in China from the perspective of pediatric drug registration and clinical trials so as to provide a reference for its improvement.Methods The regis...Objective To analyze the current status of pediatric drug development in China from the perspective of pediatric drug registration and clinical trials so as to provide a reference for its improvement.Methods The registration and clinical trials explicitly labeled as pediatric drugs were analyzed by using the Insight Database,National Medical Products Administration(NMPA),and other publicly available information.Results and Conclusion The number of applications for pediatric drug registration was 196,and 104 were for domestic drugs,accounting for 53.06%.The number of pediatric drugs included in the priority review was 116,and 70.18%have completed the review.However,the number of new pediatric drug marketing applications is still not optimistic.Only 5 applications for pediatric drug registration are accepted by Center for Drug Evaluation(CDE),accounting for 4.63%.There are difficulties in recruiting pediatric subjects in clinical trials,with 42.08%of completed recruitment projects.Besides,there are few institutions for drug clinical trials,the distribution of institutions and professional certification are uneven.Therefore,enterprises should be encouraged to carry out research and development of pediatric drugs from two aspects:improving the policy for pediatric drugs and strengthening the clinical management of pediatric drugs to guarantee their safe use.展开更多
Objective: To investigate the distribution of pathogens and risk factors of nosocomial infection in hospitalized patients in cardiovascular department. Methods: a total of 360 patients with cardiovascular diseases wer...Objective: To investigate the distribution of pathogens and risk factors of nosocomial infection in hospitalized patients in cardiovascular department. Methods: a total of 360 patients with cardiovascular diseases were admitted from January 2019 to January 2020, aged 45-80 years, 198 males and 162 females, with an average of (62.6 ± 14.3) years;There were 208 cases of coronary heart disease, 115 cases of hypertensive heart disease, 22 cases of acute myocardial infarction, 6 cases of dilated cardiomyopathy, 4 cases of rheumatic heart disease and 5 others.In the classification of cardiac function, there were 42 cases of grade I, 201 cases of grade II, 80 cases of grade III and 37 cases of grade IV.The diagnostic criteria of nosocomial infection refer to the diagnostic criteria of nosocomial infection issued by the Ministry of health in 2001.Results: the distribution of pathogens and risk factors of nosocomial infection in inpatients in vascular department, and targeted intervention and prevention are very necessary.展开更多
设计了一种新型LNG超低温调节蝶阀,其公称压力等级为ANSI Class 150,适用温度低至-196℃。研究内容涵盖了阀门的结构设计、密封与连接机制的优化,以及关键零部件的材料选择和加工工艺改进。采用双偏心结构设计,优化流道并降低启闭扭矩;...设计了一种新型LNG超低温调节蝶阀,其公称压力等级为ANSI Class 150,适用温度低至-196℃。研究内容涵盖了阀门的结构设计、密封与连接机制的优化,以及关键零部件的材料选择和加工工艺改进。采用双偏心结构设计,优化流道并降低启闭扭矩;创新开发多层复合密封系统,结合金属密封与柔性石墨密封,确保低温工况下密封可靠性。主要承压部件选用ASTM A351 Gr.CF8M奥氏体不锈钢,并采用深冷处理工艺提升材料低温韧性。通过对样机进行低温环境测试和性能验证,表明该蝶阀在LNG工况下具有高效控制性能与可靠性。研究成果为LNG关键设备国产化提供了理论依据和实践指导。展开更多
基金funded by the National Natural Science Foundation of China (31640012, 41271007, 31660232)the One Hundred Person Project of the Chinese Academy of Sciences (Y551821)+1 种基金the Opening Foundation of the State Key Laboratory Breeding Base of DesertificationAeolian Sand Disaster Combating, Gansu Desert Control Research Institute (GSDC201505)
文摘Afforestation is conducive to soil carbon（C） sequestration in semi-arid regions. However, little is known about the effects of afforestation on sequestrations of total and labile soil organic carbon（SOC） fractions in semi-arid sandy lands. In the present study, we examined the effects of Caragana microphylla Lam. plantations with different ages（12-and 25-year-old） on sequestrations of total SOC as well as labile SOC fractions such as light fraction organic carbon（LFOC） and microbial biomass carbon（MBC）. The analyzed samples were taken from soil depths of 0–5 and 5–15 cm under two shrub-related scenarios： under shrubs and between shrubs with moving sand dunes as control sites in the Horqin Sandy Land of northern China. The results showed that the concentrations and storages of total SOC at soil depths of 0–5 and 5–15 cm were higher in 12-and 25-year-old C. microphylla plantations than in moving sand dunes（i.e., control sites）, with the highest value observed under shrubs in 25-year-old C. microphylla plantations. Furthermore, the concentrations and storages of LFOC and MBC showed similar patterns with those of total SOC at the same soil depth. The 12-year-old C. microphylla plantations had higher percentages of LFOC concentration to SOC concentration and MBC concentration to SOC concentration than the 25-year-old C. microphylla plantations and moving sand dunes at both soil depths. A significant positive correlation existed among SOC, LFOC, and MBC, implying that restoring the total and labile SOC fractions is possible by afforestation with C. microphylla shrubs in the Horqin Sandy Land. At soil depth of 0–15 cm, the accumulation rate of total SOC under shrubs was higher in young C. microphylla plantations（18.53 g C/（m^2·a）; 0–12 years） than in old C. microphylla plantations（16.24 g C/（m^2·a）; 12–25 years）, and the accumulation rates of LFOC and MBC under shrubs and between shrubs were also higher in young C. microphylla plantations than in old C. microphylla plantations. It can be concluded that the establishment of C. microphylla in the Horqin Sandy Land may be a good mitigation strategy for SOC sequestration in the surface soils.
文摘为了提高窄间隙焊接的智能化水平,文中基于被动视觉传感方法,提出一种同步性好、鲁棒性强的窄间隙焊接图像坡口边缘感兴趣区域(region of interest,ROI)窗口的自适应定位方法,解决焊接过程中因坡口宽度变化带来的坡口边缘位置定位难、检测精度差的问题.通过调节坡口边缘ROI窗口水平平移量,揭示ROI窗口位置对坡口边缘图像背景与目标占比和边缘特征提取精度的影响规律,建立与电弧位置同步的坡口边缘ROI窗口生成机制,实现焊接过程中坡口边缘ROI图像的精准生成和坡口边缘的精确提取,从而提高窄间隙焊接工艺的适用性.通过变坡口焊接试验,进一步验证了所提方法在坡口边缘定位和检测中的适应性和有效性.结果表明,当坡口边缘ROI窗口顶点横坐标的水平平移量为ROI窗口宽度的50%时,检测的坡口边缘位置与平均位置差值的绝对值小于3.53μm,检测平均时间小于30 ms/帧,满足窄间隙焊接过程参数检测的精度和实时性要求.
文摘Objective To analyze the current status of pediatric drug development in China from the perspective of pediatric drug registration and clinical trials so as to provide a reference for its improvement.Methods The registration and clinical trials explicitly labeled as pediatric drugs were analyzed by using the Insight Database,National Medical Products Administration(NMPA),and other publicly available information.Results and Conclusion The number of applications for pediatric drug registration was 196,and 104 were for domestic drugs,accounting for 53.06%.The number of pediatric drugs included in the priority review was 116,and 70.18%have completed the review.However,the number of new pediatric drug marketing applications is still not optimistic.Only 5 applications for pediatric drug registration are accepted by Center for Drug Evaluation(CDE),accounting for 4.63%.There are difficulties in recruiting pediatric subjects in clinical trials,with 42.08%of completed recruitment projects.Besides,there are few institutions for drug clinical trials,the distribution of institutions and professional certification are uneven.Therefore,enterprises should be encouraged to carry out research and development of pediatric drugs from two aspects:improving the policy for pediatric drugs and strengthening the clinical management of pediatric drugs to guarantee their safe use.
文摘Objective: To investigate the distribution of pathogens and risk factors of nosocomial infection in hospitalized patients in cardiovascular department. Methods: a total of 360 patients with cardiovascular diseases were admitted from January 2019 to January 2020, aged 45-80 years, 198 males and 162 females, with an average of (62.6 ± 14.3) years;There were 208 cases of coronary heart disease, 115 cases of hypertensive heart disease, 22 cases of acute myocardial infarction, 6 cases of dilated cardiomyopathy, 4 cases of rheumatic heart disease and 5 others.In the classification of cardiac function, there were 42 cases of grade I, 201 cases of grade II, 80 cases of grade III and 37 cases of grade IV.The diagnostic criteria of nosocomial infection refer to the diagnostic criteria of nosocomial infection issued by the Ministry of health in 2001.Results: the distribution of pathogens and risk factors of nosocomial infection in inpatients in vascular department, and targeted intervention and prevention are very necessary.
文摘设计了一种新型LNG超低温调节蝶阀,其公称压力等级为ANSI Class 150,适用温度低至-196℃。研究内容涵盖了阀门的结构设计、密封与连接机制的优化,以及关键零部件的材料选择和加工工艺改进。采用双偏心结构设计,优化流道并降低启闭扭矩;创新开发多层复合密封系统,结合金属密封与柔性石墨密封,确保低温工况下密封可靠性。主要承压部件选用ASTM A351 Gr.CF8M奥氏体不锈钢,并采用深冷处理工艺提升材料低温韧性。通过对样机进行低温环境测试和性能验证,表明该蝶阀在LNG工况下具有高效控制性能与可靠性。研究成果为LNG关键设备国产化提供了理论依据和实践指导。
