The ERS-1/2 wind scatterometer （WSC） has a low resolution cell of about 50 km but provides a high repetition rate （〈4 d） and can make measurements at multiple incidence angles. In order to estimate effective surf...The ERS-1/2 wind scatterometer （WSC） has a low resolution cell of about 50 km but provides a high repetition rate （〈4 d） and can make measurements at multiple incidence angles. In order to estimate effective surface reflectivity （related to soil moisture content） over bare soil Using WSC data, an original methodology based on the advance integral equation model （AIEM） is presented, which takes advantage of its multiple view angular characteristics. This method includes two steps. First, a simplified two-parameter surface scattering model is calibrated by AIEM simulated-database over a wide parameter space. Second, regression analyses are carded out using the simulated database to build the relation between those parameters of our model at different incident angles from two observations of Mid and Fore beams. From the model simulated database, our technique works quite well in estimating Г^0. The possibility of applying the model to retrieve soil moisture is investigated using a set of data collected from the Intensive Observation Period field campaign in 1998 of the Asian Monsoon Experiment Tibet （GAME-Tibet）. The retrieved values obtained for the bare land surface are consistent with ground measurements collected in these areas and the correlation coefficient between retrieved soil moisture and the measured one reaches 0.65.展开更多
Although there was a strong steric effect,isopentenyl and geranyl moieties were successfully introduced into C3 position in flavone skeleton so as to synthesize the 3-isopentenyl flavone and 3-geranyl flavone under tw...Although there was a strong steric effect,isopentenyl and geranyl moieties were successfully introduced into C3 position in flavone skeleton so as to synthesize the 3-isopentenyl flavone and 3-geranyl flavone under two cyclization conditions（AcOH/HCl and concentrated H 2 SO 4 /MeOH） in this report.It was found that the optimum cyclization conditions for 3-isopentenyl flavone and 3-geranyl flavone were,respectively,AcOH/HCl and H 2 SO 4 /MeOH.Furthermore,the donating electron ability is in the sequence 3-geranyl flavone3-isopentenyl flavone according to the density functional theory（DFT） calculations,suggesting the longer alkyl chain at 3-position would be more favorable for enhancing the donating electron ability.The present synthetic routes might reveal potential applicability in our continued studies on the total syntheses of other natural 3-alkyl flavonoids.展开更多
The three-dimensional quantitative structure-activity relationships(3D-QSAR)for 37 curcumin derivatives were constructed by CoMFA and CoMSIA methods,respectively.The results showed that the cross validated coefficient...The three-dimensional quantitative structure-activity relationships(3D-QSAR)for 37 curcumin derivatives were constructed by CoMFA and CoMSIA methods,respectively.The results showed that the cross validated coefficient(q^2)and non-cross-validated coefficient(R^2)were 0.711,0.962 in CoMFA model and 0.774,0.856 in CoMSIA model,respectively,which suggests that two models are robust and have good exterior predictive capabilities.Based on these two models and the binding mode with tubulin,nine novel curcuminoids inhibitors which could exhibit much higher anticancer potency and efficiently occupy the colchicine binding site of tubulin,were designed.We expect that the results in this paper have the potential to facilitate the process of design and to develop new potent curcumin derivatives with stronger anticancer activities.展开更多
基金Project 90302008 supported by National Natural Science Foundation of China
文摘The ERS-1/2 wind scatterometer （WSC） has a low resolution cell of about 50 km but provides a high repetition rate （〈4 d） and can make measurements at multiple incidence angles. In order to estimate effective surface reflectivity （related to soil moisture content） over bare soil Using WSC data, an original methodology based on the advance integral equation model （AIEM） is presented, which takes advantage of its multiple view angular characteristics. This method includes two steps. First, a simplified two-parameter surface scattering model is calibrated by AIEM simulated-database over a wide parameter space. Second, regression analyses are carded out using the simulated database to build the relation between those parameters of our model at different incident angles from two observations of Mid and Fore beams. From the model simulated database, our technique works quite well in estimating Г^0. The possibility of applying the model to retrieve soil moisture is investigated using a set of data collected from the Intensive Observation Period field campaign in 1998 of the Asian Monsoon Experiment Tibet （GAME-Tibet）. The retrieved values obtained for the bare land surface are consistent with ground measurements collected in these areas and the correlation coefficient between retrieved soil moisture and the measured one reaches 0.65.
基金Supported by the National Natural Science Foundation of China(No.20062001)the Natural Science Foundation of Guangxi Zhuang Autonomous Region,China(Nos.0991009 and 0447036)
文摘Although there was a strong steric effect,isopentenyl and geranyl moieties were successfully introduced into C3 position in flavone skeleton so as to synthesize the 3-isopentenyl flavone and 3-geranyl flavone under two cyclization conditions（AcOH/HCl and concentrated H 2 SO 4 /MeOH） in this report.It was found that the optimum cyclization conditions for 3-isopentenyl flavone and 3-geranyl flavone were,respectively,AcOH/HCl and H 2 SO 4 /MeOH.Furthermore,the donating electron ability is in the sequence 3-geranyl flavone3-isopentenyl flavone according to the density functional theory（DFT） calculations,suggesting the longer alkyl chain at 3-position would be more favorable for enhancing the donating electron ability.The present synthetic routes might reveal potential applicability in our continued studies on the total syntheses of other natural 3-alkyl flavonoids.
基金Supported by National Natural Science Foundation of China (2170203421861007)+2 种基金the Research Foundation of Education Bureau of Guangxi Province (200103YB076)Natural Science Foundation of Guangxi Province (2017GXNSFBA198089)“BAGUI Scholar” Program of Guangxi Province of China。
文摘The three-dimensional quantitative structure-activity relationships(3D-QSAR)for 37 curcumin derivatives were constructed by CoMFA and CoMSIA methods,respectively.The results showed that the cross validated coefficient(q^2)and non-cross-validated coefficient(R^2)were 0.711,0.962 in CoMFA model and 0.774,0.856 in CoMSIA model,respectively,which suggests that two models are robust and have good exterior predictive capabilities.Based on these two models and the binding mode with tubulin,nine novel curcuminoids inhibitors which could exhibit much higher anticancer potency and efficiently occupy the colchicine binding site of tubulin,were designed.We expect that the results in this paper have the potential to facilitate the process of design and to develop new potent curcumin derivatives with stronger anticancer activities.
