建立了特殊医学用途配方食品中非法添加的13种降糖类化学成分的通过式固相萃取净化/超高效液相色谱-串联质谱检测方法。样品用90%乙腈水溶液(含1%甲酸)提取后,提取液经Oasis PRi ME HLB固相萃取柱净化,以Waters ACQUITY UPLC BEH C18(15...建立了特殊医学用途配方食品中非法添加的13种降糖类化学成分的通过式固相萃取净化/超高效液相色谱-串联质谱检测方法。样品用90%乙腈水溶液(含1%甲酸)提取后,提取液经Oasis PRi ME HLB固相萃取柱净化,以Waters ACQUITY UPLC BEH C18(150 mm×2.1 mm,1.7μm)色谱柱分离,以甲醇-含0.1%甲酸的5 mmol/L乙酸铵溶液为流动相梯度洗脱,正离子模式电喷雾电离,配合多反应离子扫描(MRM)定性定量分析目标化合物。考察了提取剂用量、甲酸及乙腈含量对加标回收率的影响,优化了主要的影响因素和实验条件。结果表明:13种化合物在2~100μg/L范围内线性关系良好,相关系数r2≥0.995 1;方法回收率为80.9%~102.8%;定量下限为0.3~1.0μg/kg。该方法前处理简单,回收率高,重现性好,可作为降糖类特殊医学用途配方食品中非法添加降糖类化学成分的有效检测方法。展开更多
目的探究影响桡骨远端关节内骨折术后发生切口感染的相关危险因素,为预防此类并发症提供证据支持。方法回顾性分析手术治疗桡骨远端关节内骨折患者627例的临床资料,查阅电子病历系统、影像系统和检验报告,调取患者术周资料以及检验结果...目的探究影响桡骨远端关节内骨折术后发生切口感染的相关危险因素,为预防此类并发症提供证据支持。方法回顾性分析手术治疗桡骨远端关节内骨折患者627例的临床资料,查阅电子病历系统、影像系统和检验报告,调取患者术周资料以及检验结果。根据美国疾病防治中心(Centers for Disease Control,CDC)定义感染标准确定是否发生切口感染。采用Logistics回归分析确定影响桡骨远端关节内骨折术后发生切口感染的危险因素。结果观察期内发生切口感染42例,切口感染发生率为6.7%。不同年龄、体重指数、吸烟状态、糖尿病、风湿免疫疾病、骨折AO分型、骨折类型、手术时机、美国麻醉协会(American Society of Anesthesiologists,ASA)分级、手术时间、术前血红蛋白水平以及白蛋白水平桡骨远端关节内骨折患者术后发生切口感染发生率差异有统计学意义(P<0.05或P<0.01)。多因素Logistics回归分析显示,吸烟、开放骨折GustiloⅡ~Ⅲ型、手术时间>130 min和术前白蛋白水平<35 g/L是桡骨远端关节内术后发生切口感染的影响因素。结论这些因素的探究对于评估罹患感染的风险具有重要意义,及时戒烟、合理规划手术流程以减少手术时间、并及时补充营养以减少切口感染风险。展开更多
Village landscapes, which integrate small-scale agriculture with housing, forestry, and a host of other land use practices, cover more than 2 million square kilometers across China. Village lands tend to be managed at...Village landscapes, which integrate small-scale agriculture with housing, forestry, and a host of other land use practices, cover more than 2 million square kilometers across China. Village lands tend to be managed at very fine spatial scales (≤ 30 m), with managers both adapting their practices to existing variation in soils and terrain (e.g., fertile plains vs. infertile slopes) and also altering soil fertility and even terrain by terracing, irrigation, fertilizing, and other land use practices. Relationships between fine-scale land management patterns and soil organic carbon (SOC) in the top 30 cm of village soils were studied by sampling soils within fine-scale landscape features using a regionally weighted landscape sampling design across five environmentally distinct sites in China. SOC stocks across China’s village regions (5 Pg C in the top 30 cm of 2 × 10 6 km 2 ) represent roughly 4% of the total SOC stocks in global croplands. Although macroclimate varied from temperate to tropical in this study, SOC density did not vary significantly with climate, though it was negatively correlated with regional mean elevation. The highest SOC densities within landscapes were found in agricultural lands, especially paddy, the lowest SOC densities were found in nonproductive lands, and forest lands tended toward moderate SOC densities. Due to the high SOC densities of agricultural lands and their predominance in village landscapes, most village SOC was found in agricultural land, except in the tropical hilly region, where forestry accounted for about 45% of the SOC stocks. A surprisingly large portion of village SOC was associated with built structures and with the disturbed lands surrounding these structures, ranging from > 18% in the North China Plain to about 9% in the tropical hilly region. These results confirmed that local land use practices, combined with local and regional variation in terrain, were associated with most of the SOC variation within and across China’s village landscapes and may be an important cause of regional variation in SOC.展开更多
Halogenated methyl-phenyl ethers （anisoles） are ubiquitous organic compounds in the environment. In the present study, geometrical optimization and electrostatic potential calculations have been performed for 42 hal...Halogenated methyl-phenyl ethers （anisoles） are ubiquitous organic compounds in the environment. In the present study, geometrical optimization and electrostatic potential calculations have been performed for 42 halogenated anisoles at the HF/6-31 G^＊ level. A number of statistically based parameters have been obtained. By multiple regression method, linear relationships between the gas-chromatographic relative retention time （RRT） and structural descriptors have been established for the training set of 32 halogenated anisoles. The result showed that the parameters derived from electrostatic potentials （ESPs） together with the molecular volume （Vmc） could be well used to express the quantitative structure-RRT relationships of halogenated anisoles. The best two-variable regression model gives a correlation coefficient of 0.980 and a standard deviation of 0.07, and the leave-one-out cross-validated correlation coefficient is 0.975. The goodness of the model has been further validated through exploring the predictive power for the testing set of 10 halogenated anisoles.展开更多
文摘目的探究影响桡骨远端关节内骨折术后发生切口感染的相关危险因素,为预防此类并发症提供证据支持。方法回顾性分析手术治疗桡骨远端关节内骨折患者627例的临床资料,查阅电子病历系统、影像系统和检验报告,调取患者术周资料以及检验结果。根据美国疾病防治中心(Centers for Disease Control,CDC)定义感染标准确定是否发生切口感染。采用Logistics回归分析确定影响桡骨远端关节内骨折术后发生切口感染的危险因素。结果观察期内发生切口感染42例,切口感染发生率为6.7%。不同年龄、体重指数、吸烟状态、糖尿病、风湿免疫疾病、骨折AO分型、骨折类型、手术时机、美国麻醉协会(American Society of Anesthesiologists,ASA)分级、手术时间、术前血红蛋白水平以及白蛋白水平桡骨远端关节内骨折患者术后发生切口感染发生率差异有统计学意义(P<0.05或P<0.01)。多因素Logistics回归分析显示,吸烟、开放骨折GustiloⅡ~Ⅲ型、手术时间>130 min和术前白蛋白水平<35 g/L是桡骨远端关节内术后发生切口感染的影响因素。结论这些因素的探究对于评估罹患感染的风险具有重要意义,及时戒烟、合理规划手术流程以减少手术时间、并及时补充营养以减少切口感染风险。
基金Project supported by the US National Science Foundation (No. DEB-0075617)
文摘Village landscapes, which integrate small-scale agriculture with housing, forestry, and a host of other land use practices, cover more than 2 million square kilometers across China. Village lands tend to be managed at very fine spatial scales (≤ 30 m), with managers both adapting their practices to existing variation in soils and terrain (e.g., fertile plains vs. infertile slopes) and also altering soil fertility and even terrain by terracing, irrigation, fertilizing, and other land use practices. Relationships between fine-scale land management patterns and soil organic carbon (SOC) in the top 30 cm of village soils were studied by sampling soils within fine-scale landscape features using a regionally weighted landscape sampling design across five environmentally distinct sites in China. SOC stocks across China’s village regions (5 Pg C in the top 30 cm of 2 × 10 6 km 2 ) represent roughly 4% of the total SOC stocks in global croplands. Although macroclimate varied from temperate to tropical in this study, SOC density did not vary significantly with climate, though it was negatively correlated with regional mean elevation. The highest SOC densities within landscapes were found in agricultural lands, especially paddy, the lowest SOC densities were found in nonproductive lands, and forest lands tended toward moderate SOC densities. Due to the high SOC densities of agricultural lands and their predominance in village landscapes, most village SOC was found in agricultural land, except in the tropical hilly region, where forestry accounted for about 45% of the SOC stocks. A surprisingly large portion of village SOC was associated with built structures and with the disturbed lands surrounding these structures, ranging from > 18% in the North China Plain to about 9% in the tropical hilly region. These results confirmed that local land use practices, combined with local and regional variation in terrain, were associated with most of the SOC variation within and across China’s village landscapes and may be an important cause of regional variation in SOC.
基金This work was supported by the National Natural Science Foundation of China (No. 20502022) and the Ph.D. Fund of Ningbo ( No. 2004A610010)
文摘Halogenated methyl-phenyl ethers （anisoles） are ubiquitous organic compounds in the environment. In the present study, geometrical optimization and electrostatic potential calculations have been performed for 42 halogenated anisoles at the HF/6-31 G^＊ level. A number of statistically based parameters have been obtained. By multiple regression method, linear relationships between the gas-chromatographic relative retention time （RRT） and structural descriptors have been established for the training set of 32 halogenated anisoles. The result showed that the parameters derived from electrostatic potentials （ESPs） together with the molecular volume （Vmc） could be well used to express the quantitative structure-RRT relationships of halogenated anisoles. The best two-variable regression model gives a correlation coefficient of 0.980 and a standard deviation of 0.07, and the leave-one-out cross-validated correlation coefficient is 0.975. The goodness of the model has been further validated through exploring the predictive power for the testing set of 10 halogenated anisoles.
