The nitrogen nutrition index(NNI)is a reliable indicator for diagnosing crop nitrogen(N)status.However,there is currently no specific vegetation index for the NNI inversion across multiple growth periods.To overcome t...The nitrogen nutrition index(NNI)is a reliable indicator for diagnosing crop nitrogen(N)status.However,there is currently no specific vegetation index for the NNI inversion across multiple growth periods.To overcome the limitations of the traditional direct NNI inversion method(NNI_(T1))of the vegetation index and traditional indirect NNI inversion method(NNI_(T2))by inverting intermediate variables including the aboveground dry biomass(AGB)and plant N concentration(PNC),this study proposed a new NNI remote sensing index(NNI_(RS)).A remote-sensing-based critical N dilution curve(Nc_(_RS))was set up directly from two vegetation indices and then used to calculate NNI_(RS).Field data including AGB,PNC,and canopy hyperspectral data were collected over four growing seasons(2012–2013(Exp.1),2013–2014(Exp.2),2014–2015(Exp.3),2015–2016(Exp.4))in Beijing,China.All experimental datasets were cross-validated to each of the NNI models(NNI_(T1),NNI_(T2)and NNI_(RS)).The results showed that:(1)the NNI_(RS)models were represented by the standardized leaf area index determining index(sLAIDI)and the red-edge chlorophyll index(CI_(red edge))in the form of NNI_(RS)=CI_(red edge)/(a×sLAIDI~b),where"a"equals 2.06,2.10,2.08 and 2.02 and"b"equals 0.66,0.73,0.67 and 0.62 when the modeling set data came from Exp.1/2/4,Exp.1/2/3,Exp.1/3/4,and Exp.2/3/4,respectively;(2)the NNI_(RS)models achieved better performance than the other two NNI revised methods,and the ranges of R2 and RMSE were 0.50–0.82 and 0.12–0.14,respectively;(3)when the remaining data were used for verification,the NNI_(RS)models also showed good stability,with RMSE values of 0.09,0.18,0.13 and 0.10,respectively.Therefore,it is concluded that the NNI_(RS)method is promising for the remote assessment of crop N status.展开更多
基于在pH 8.6的甘氨酸-氢氧化钠-乙腈体系中,硼氢化钠可以将孔雀石绿(MG)定量还原为隐性孔雀石绿(LMG)从而具有荧光,表面活性剂十二烷基磺酸钠(SDS)的加入能使LMG荧光强度增强并稳定,建立了测定水产品中MG和LMG的同步荧光分光光度法.用...基于在pH 8.6的甘氨酸-氢氧化钠-乙腈体系中,硼氢化钠可以将孔雀石绿(MG)定量还原为隐性孔雀石绿(LMG)从而具有荧光,表面活性剂十二烷基磺酸钠(SDS)的加入能使LMG荧光强度增强并稳定,建立了测定水产品中MG和LMG的同步荧光分光光度法.用正交试验设计对测定的实验条件进行了优化,结果发现:0.70 m L的甘氨酸-氢氧化钠-乙腈体系(pH 8.6),0.30 m L 0.2 mol/L Na BH4,0.50 m L浓度为1×10-4mol/L的SDS,避光放置7 min,以同步波长差△λ=98 nm进行同步荧光扫描,MG浓度在1.0×10-7~1.0×10-6mol/L线性范围与其同步荧光强度成正比,相关系数r为0.998,检出限为2.4×10-8mol/L.应用于水产品中MG和LMG的测定,加标回收率为95.3%~101.3%,RSD为4.2%~6.7%.展开更多
We investigate the dependence of elliptic flows v2 on transverse momentum PT for charged hadrons produced in nucleus-nucleus collisions at high energy by using a multi-source thermal model,where the contribution of so...We investigate the dependence of elliptic flows v2 on transverse momentum PT for charged hadrons produced in nucleus-nucleus collisions at high energy by using a multi-source thermal model,where the contribution of source interactions is considered.Our calculated results are approximately in agrcement with the experimental data over a wider PT range from the PHENIX and ALICE collaborations.It is found that the expansion factor increases linearly with the impact parameter from most central (0-5%) to mid-peripheral (35-40%) collisions.展开更多
基金supported by the earmarked fund for China Agriculture Research System(CARS-03)the National Key Research and Development Program of China(2017YFD0201501 and 2016YFD020060306)the National Natural Science Foundation of China(41701375 and 61661136003)。
文摘The nitrogen nutrition index(NNI)is a reliable indicator for diagnosing crop nitrogen(N)status.However,there is currently no specific vegetation index for the NNI inversion across multiple growth periods.To overcome the limitations of the traditional direct NNI inversion method(NNI_(T1))of the vegetation index and traditional indirect NNI inversion method(NNI_(T2))by inverting intermediate variables including the aboveground dry biomass(AGB)and plant N concentration(PNC),this study proposed a new NNI remote sensing index(NNI_(RS)).A remote-sensing-based critical N dilution curve(Nc_(_RS))was set up directly from two vegetation indices and then used to calculate NNI_(RS).Field data including AGB,PNC,and canopy hyperspectral data were collected over four growing seasons(2012–2013(Exp.1),2013–2014(Exp.2),2014–2015(Exp.3),2015–2016(Exp.4))in Beijing,China.All experimental datasets were cross-validated to each of the NNI models(NNI_(T1),NNI_(T2)and NNI_(RS)).The results showed that:(1)the NNI_(RS)models were represented by the standardized leaf area index determining index(sLAIDI)and the red-edge chlorophyll index(CI_(red edge))in the form of NNI_(RS)=CI_(red edge)/(a×sLAIDI~b),where"a"equals 2.06,2.10,2.08 and 2.02 and"b"equals 0.66,0.73,0.67 and 0.62 when the modeling set data came from Exp.1/2/4,Exp.1/2/3,Exp.1/3/4,and Exp.2/3/4,respectively;(2)the NNI_(RS)models achieved better performance than the other two NNI revised methods,and the ranges of R2 and RMSE were 0.50–0.82 and 0.12–0.14,respectively;(3)when the remaining data were used for verification,the NNI_(RS)models also showed good stability,with RMSE values of 0.09,0.18,0.13 and 0.10,respectively.Therefore,it is concluded that the NNI_(RS)method is promising for the remote assessment of crop N status.
文摘基于在pH 8.6的甘氨酸-氢氧化钠-乙腈体系中,硼氢化钠可以将孔雀石绿(MG)定量还原为隐性孔雀石绿(LMG)从而具有荧光,表面活性剂十二烷基磺酸钠(SDS)的加入能使LMG荧光强度增强并稳定,建立了测定水产品中MG和LMG的同步荧光分光光度法.用正交试验设计对测定的实验条件进行了优化,结果发现:0.70 m L的甘氨酸-氢氧化钠-乙腈体系(pH 8.6),0.30 m L 0.2 mol/L Na BH4,0.50 m L浓度为1×10-4mol/L的SDS,避光放置7 min,以同步波长差△λ=98 nm进行同步荧光扫描,MG浓度在1.0×10-7~1.0×10-6mol/L线性范围与其同步荧光强度成正比,相关系数r为0.998,检出限为2.4×10-8mol/L.应用于水产品中MG和LMG的测定,加标回收率为95.3%~101.3%,RSD为4.2%~6.7%.
基金Supported by the National Natural Science Foundation of China under Grant Nos 10975095 and 11005071the National Fun-damental Fund of Personnel Training(J1103210)+1 种基金the Shanxi Provincial Natural Science Foundation under Grant Nos 2007011005 and 2011011001the Shanxi Scholarship Council.
文摘We investigate the dependence of elliptic flows v2 on transverse momentum PT for charged hadrons produced in nucleus-nucleus collisions at high energy by using a multi-source thermal model,where the contribution of source interactions is considered.Our calculated results are approximately in agrcement with the experimental data over a wider PT range from the PHENIX and ALICE collaborations.It is found that the expansion factor increases linearly with the impact parameter from most central (0-5%) to mid-peripheral (35-40%) collisions.
