由公式C<sub>n</sub><sup>k</sup>+C<sub>n</sub><sup>k+1</sup>=C<sub>n+1</sub><sup>k+1</sup>,可得:C<sub>2</sub><sup>2</sup>+...由公式C<sub>n</sub><sup>k</sup>+C<sub>n</sub><sup>k+1</sup>=C<sub>n+1</sub><sup>k+1</sup>,可得:C<sub>2</sub><sup>2</sup>+C<sub>3</sub><sup>2</sup>+…+C<sub>n</sub><sup>2</sup>=C<sub>n+1</sub><sup>3</sup>,sum from k=2 to nC<sub>k</sub><sup>2</sup>=C<sub>n+1</sub><sup>3</sup>,展开更多
关于自然数组成的级数sum from k=1 to ∞ （k）和自然数平方组成的级数sum from k=1 to ∞ （k<sup>2</sup>）的前n项求和公式: S<sub>1</sub>（n）=sum from k=1 to n （k）=n（n+1）/2 S<sub>2</su...关于自然数组成的级数sum from k=1 to ∞ （k）和自然数平方组成的级数sum from k=1 to ∞ （k<sup>2</sup>）的前n项求和公式: S<sub>1</sub>（n）=sum from k=1 to n （k）=n（n+1）/2 S<sub>2</sub>（n）=sum from k=1 to n （k<sup>2</sup>）=1/6n（n+1）（2n+1） （2）我们大家非常熟悉,并且在一些文献中分别给出不同的证明。本文利用公式（1）,（2）介绍几种自然数立方组成的级数sum from k=1 to ∞ （k<sup>3</sup>）的前n项和公式:展开更多
The development of an efficient artificial H_(2)O_(2) photosynthesis system is a challenging work using H_(2)O and O_(2) as starting materials.Herein,3D In_(2.77)S_(4) nanoflower precursor was in-situ deposited on K^(...The development of an efficient artificial H_(2)O_(2) photosynthesis system is a challenging work using H_(2)O and O_(2) as starting materials.Herein,3D In_(2.77)S_(4) nanoflower precursor was in-situ deposited on K^(+)-doped g-C_(3)N_(4)(KCN)nanosheets using a solvothermal method,then In_(2.77)S_(4)/KCN(IS/KCN)het-erojunction with an intimate interface was obtained after a calcination process.The investigation shows that the photocatalytic H_(2)O_(2) production rate of 50IS/KCN can reach up to 1.36 mmol g^(-1)h^(-1)without any sacrificial reagents under visible light irradiation,which is 9.2 times and 4.1 times higher than that of KCN and In_(2.77)S_(4)/respectively.The enhanced activity of the above composite can be mainly attributed to the S-scheme charge transfer route between KCN and In_(2.77)S_(4) according to density functional theory calculations,electron paramagnetic resonance and free radical capture tests,leading to an expanded light response range and rapid charge separation at their interface,as well as preserving the active electrons and holes for H_(2)O_(2) production.Besides,the unique 3D nanostructure and surface hydrophobicity of IS/KCN facilitate the diffusion and transportation of O_(2) around the active centers,the energy barriers of O_(2) protonation and H_(2)O_(2) desorption steps are ef-fectively reduced over the composite.In addition,this system also exhibits excellent light harvesting ability and stability.This work provides a potential strategy to explore a sustainable H_(2)O_(2) photo-synthesis pathway through the design of heterojunctions with intimate interfaces and desired reac-tion thermodynamics and kinetics.展开更多
目的:探讨血清生物标志物甲胎蛋白(AFP)、维生素K缺失或拮抗剂Ⅱ诱导的蛋白质(PIVKA-Ⅱ)和磷脂酰肌醇蛋白聚糖3(GPC-3)单独或联合用于肝细胞癌(以下简称肝癌)诊断的价值。方法:检索PubMed、Web of Science、Embase三个数据库,收集2002...目的:探讨血清生物标志物甲胎蛋白(AFP)、维生素K缺失或拮抗剂Ⅱ诱导的蛋白质(PIVKA-Ⅱ)和磷脂酰肌醇蛋白聚糖3(GPC-3)单独或联合用于肝细胞癌(以下简称肝癌)诊断的价值。方法:检索PubMed、Web of Science、Embase三个数据库,收集2002年以来发表的AFP、PIVKA-Ⅱ和GPC-3单独或联合用于诊断肝癌的文献。根据纳入和排除标准筛选文献并提取相关数据。利用诊断准确性研究的质量评价(QUADAS)检查表对纳入的文献进行质量评价,并采用Meta DiSc软件、Review Manager 5.4软件和Stata 15.1软件对AFP、PIVKA-Ⅱ和GPC-3单用和联合使用诊断肝癌的受试者工作特征曲线下面积(AUC)、敏感度、特异度等指标进行数据分析。结果:共纳入32篇文献。Meta分析结果显示,单个标志物用于诊断肝癌时,PIVKA-Ⅱ的AUC值最高,为0.88(95%CI:0.85~0.91),其次是GPC-3和AFP;多个标志物联合用于诊断肝癌的AUC均高于单个标志物,其中PIVKA-Ⅱ联合GPC-3诊断的AUC值最高,为0.90(95%CI:0.87~0.92)。单个标志物用于诊断肝癌时,PIVKA-Ⅱ和GPC-3的敏感度相对较高(分别为0.75和0.76),但GPC-3的特异度不如PIVKA-Ⅱ和AFP(AFP、PIVKA-Ⅱ和GPC-3分别为0.87、0.88和0.81);多个标志物联合用于诊断肝癌的敏感度较单个标志物诊断时有所提高,但特异度无明显提高。单个标志物用于诊断肝癌时,PIVKA-Ⅱ的诊断比值比(DOR)最高,为22(95%CI:13~36),其次是GPC-3和AFP;两个标志物联合用于诊断肝癌的DOR均高于单个标志物,其中AFP联合GPC-3诊断的DOR最高,为25(95%CI:9~67);三个标志物联合用于诊断肝癌时的DOR明显降低,为10(95%CI:7~45)。结论:单个标志物用于肝癌诊断时,PIVKA-Ⅱ的诊断价值更高。两种标志物联合能显著提高肝癌诊断的敏感度,三种标志物联合未能进一步提高诊断价值。结合临床实际,推荐AFP联合PIVKA-Ⅱ用于肝癌的诊断。展开更多
文摘由公式C<sub>n</sub><sup>k</sup>+C<sub>n</sub><sup>k+1</sup>=C<sub>n+1</sub><sup>k+1</sup>,可得:C<sub>2</sub><sup>2</sup>+C<sub>3</sub><sup>2</sup>+…+C<sub>n</sub><sup>2</sup>=C<sub>n+1</sub><sup>3</sup>,sum from k=2 to nC<sub>k</sub><sup>2</sup>=C<sub>n+1</sub><sup>3</sup>,
文摘关于自然数组成的级数sum from k=1 to ∞ （k）和自然数平方组成的级数sum from k=1 to ∞ （k<sup>2</sup>）的前n项求和公式: S<sub>1</sub>（n）=sum from k=1 to n （k）=n（n+1）/2 S<sub>2</sub>（n）=sum from k=1 to n （k<sup>2</sup>）=1/6n（n+1）（2n+1） （2）我们大家非常熟悉,并且在一些文献中分别给出不同的证明。本文利用公式（1）,（2）介绍几种自然数立方组成的级数sum from k=1 to ∞ （k<sup>3</sup>）的前n项和公式:
文摘The development of an efficient artificial H_(2)O_(2) photosynthesis system is a challenging work using H_(2)O and O_(2) as starting materials.Herein,3D In_(2.77)S_(4) nanoflower precursor was in-situ deposited on K^(+)-doped g-C_(3)N_(4)(KCN)nanosheets using a solvothermal method,then In_(2.77)S_(4)/KCN(IS/KCN)het-erojunction with an intimate interface was obtained after a calcination process.The investigation shows that the photocatalytic H_(2)O_(2) production rate of 50IS/KCN can reach up to 1.36 mmol g^(-1)h^(-1)without any sacrificial reagents under visible light irradiation,which is 9.2 times and 4.1 times higher than that of KCN and In_(2.77)S_(4)/respectively.The enhanced activity of the above composite can be mainly attributed to the S-scheme charge transfer route between KCN and In_(2.77)S_(4) according to density functional theory calculations,electron paramagnetic resonance and free radical capture tests,leading to an expanded light response range and rapid charge separation at their interface,as well as preserving the active electrons and holes for H_(2)O_(2) production.Besides,the unique 3D nanostructure and surface hydrophobicity of IS/KCN facilitate the diffusion and transportation of O_(2) around the active centers,the energy barriers of O_(2) protonation and H_(2)O_(2) desorption steps are ef-fectively reduced over the composite.In addition,this system also exhibits excellent light harvesting ability and stability.This work provides a potential strategy to explore a sustainable H_(2)O_(2) photo-synthesis pathway through the design of heterojunctions with intimate interfaces and desired reac-tion thermodynamics and kinetics.
