2,3,4,6-Tetra-O-acetyl-α-D-galactopyranosyl bromide reacted with carboxylic acids in the presence of CaH_2 and Ag_2CO_3 and small amount of I_2 to give good yields of l-O-acyl-β-D- galactopyranose tetraaeetates.β-A...2,3,4,6-Tetra-O-acetyl-α-D-galactopyranosyl bromide reacted with carboxylic acids in the presence of CaH_2 and Ag_2CO_3 and small amount of I_2 to give good yields of l-O-acyl-β-D- galactopyranose tetraaeetates.β-Anomers of glycosyl esters were obtained by this improved Koenigs-Knorr method.展开更多
Using traditional five-interferogram algorithm to unwrap phase for length measurement, the phase steps must be equal to π/2 exactly, but it is almost impossible to achieve in nanometer positioning technique. Aiming t...Using traditional five-interferogram algorithm to unwrap phase for length measurement, the phase steps must be equal to π/2 exactly, but it is almost impossible to achieve in nanometer positioning technique. Aiming to overcome this defect of traditional five-interferogram algorithm, an improved five-interferogram algorithm is presented. This improved algorithm not only keeps the high accuracy of traditional fiveinterferogram algorithm, but also does not need absolute equal step to unwrap phase. Instead, this algorithm only needs measuring phase-shifting. With the numerical simulation, the improved five-interferogram algorithm shows high accuracy, high reliability, and feasibility in practice. It is very valuable for accurate length measurement with Fizeau interferometer and Fabry-Perot interferometer.展开更多
The remote measurement of the vertical distribution of acoustical parameters of the sea bottom is an inverse method in acoustics. The existing methods can be divided into two types: the wave method and the ray method....The remote measurement of the vertical distribution of acoustical parameters of the sea bottom is an inverse method in acoustics. The existing methods can be divided into two types: the wave method and the ray method. The former usually does not apply to cases with discontinuity in acoustical parameter profiles[1] , whereas the latter usually ignores the contributions made by multiple reflections, resulting in the appearance of pseudo interfaces. However, under certain practical circumstances, the ray method can produce satisfactory results[2,3]. In this paper, at first we use the conception of equitime layer thickness to obtain the pulse response iteration method. The anti-interference capability of this method is poor. In order to improve this capability, we develope the sample iteration method and the sample-averaging iteration method. The sample-averaging iteration method introduces a way of statistical averaging, which can further improve the anti-interference capability.展开更多
Guiding college students to acquire an adequate vocabularyis an important task that is often neglected. The morevocabulary hat is mastered, the higher level a learner of Englishwill have. But in China, the traditional...Guiding college students to acquire an adequate vocabularyis an important task that is often neglected. The morevocabulary hat is mastered, the higher level a learner of Englishwill have. But in China, the traditional method of teachingvocabulary is learning by rote, and learners of foreign languagesare inclined to learn as much vocabulary as possible this wayregardless of whether these vocabulary is useful or not. Indeed,there are some disadvantageous factors hindering the studentsfrom expanding vocabulary rapidly and efficiently. We have todevelop a scientific method of teaching vocabulary exploringmethods of which is the key to this article.展开更多
In this work, a bimetallic zeolitic imidazolate framework （ZIF） CoZn-ZIF was synthesized via a facile sol-vothermal approach and applied in lithiumion batteries. The as-prepared CoZn-ZIF shows a high reversible capa...In this work, a bimetallic zeolitic imidazolate framework （ZIF） CoZn-ZIF was synthesized via a facile sol-vothermal approach and applied in lithiumion batteries. The as-prepared CoZn-ZIF shows a high reversible capacity of 605.8 mA b g-i at a current density of 100 mA g^-1, far beyond the performance of the corresponding monometallic Co-ZIF- 67 and Zn-ZIF-8. Ex-situ synchrotron soft X-ray absorption spectroscopy, X-ray diffraction, and electron paramagnetic resonance techniques were employed to explore the Li^storage mechanism. The superior performance of CoZn-ZIF over Co-ZIF-67 and Zn-ZIF-8 could be mainly attributed to lithiation and delithiation of nitrogen atoms, accompanied by the breakage and recoordination of metal nitrogen bond. Morever, a few metal nitrogen bonds without recoordination will lead to the amorphization of CoZn-ZIF and the formation of few nitrogen radicals.展开更多
文摘2,3,4,6-Tetra-O-acetyl-α-D-galactopyranosyl bromide reacted with carboxylic acids in the presence of CaH_2 and Ag_2CO_3 and small amount of I_2 to give good yields of l-O-acyl-β-D- galactopyranose tetraaeetates.β-Anomers of glycosyl esters were obtained by this improved Koenigs-Knorr method.
基金the Ministry of Science and Technology of China under Grant No.2002DEA20014.
文摘Using traditional five-interferogram algorithm to unwrap phase for length measurement, the phase steps must be equal to π/2 exactly, but it is almost impossible to achieve in nanometer positioning technique. Aiming to overcome this defect of traditional five-interferogram algorithm, an improved five-interferogram algorithm is presented. This improved algorithm not only keeps the high accuracy of traditional fiveinterferogram algorithm, but also does not need absolute equal step to unwrap phase. Instead, this algorithm only needs measuring phase-shifting. With the numerical simulation, the improved five-interferogram algorithm shows high accuracy, high reliability, and feasibility in practice. It is very valuable for accurate length measurement with Fizeau interferometer and Fabry-Perot interferometer.
文摘The remote measurement of the vertical distribution of acoustical parameters of the sea bottom is an inverse method in acoustics. The existing methods can be divided into two types: the wave method and the ray method. The former usually does not apply to cases with discontinuity in acoustical parameter profiles[1] , whereas the latter usually ignores the contributions made by multiple reflections, resulting in the appearance of pseudo interfaces. However, under certain practical circumstances, the ray method can produce satisfactory results[2,3]. In this paper, at first we use the conception of equitime layer thickness to obtain the pulse response iteration method. The anti-interference capability of this method is poor. In order to improve this capability, we develope the sample iteration method and the sample-averaging iteration method. The sample-averaging iteration method introduces a way of statistical averaging, which can further improve the anti-interference capability.
文摘Guiding college students to acquire an adequate vocabularyis an important task that is often neglected. The morevocabulary hat is mastered, the higher level a learner of Englishwill have. But in China, the traditional method of teachingvocabulary is learning by rote, and learners of foreign languagesare inclined to learn as much vocabulary as possible this wayregardless of whether these vocabulary is useful or not. Indeed,there are some disadvantageous factors hindering the studentsfrom expanding vocabulary rapidly and efficiently. We have todevelop a scientific method of teaching vocabulary exploringmethods of which is the key to this article.
基金supported by the National Natural Science Foundation of China for Excellent Young Scholars(21522303)the National Natural Science Foundation of China(21373086)+3 种基金the Basic Research Project of Shanghai Science and Technology Committee(14JC1491000)the Large Instruments Open Foundation of East China Normal Universitythe National Key Basic Research Program of China(2013CB921800)the National High Technology Research and Development Program of China(2014AA123401)
文摘In this work, a bimetallic zeolitic imidazolate framework （ZIF） CoZn-ZIF was synthesized via a facile sol-vothermal approach and applied in lithiumion batteries. The as-prepared CoZn-ZIF shows a high reversible capacity of 605.8 mA b g-i at a current density of 100 mA g^-1, far beyond the performance of the corresponding monometallic Co-ZIF- 67 and Zn-ZIF-8. Ex-situ synchrotron soft X-ray absorption spectroscopy, X-ray diffraction, and electron paramagnetic resonance techniques were employed to explore the Li^storage mechanism. The superior performance of CoZn-ZIF over Co-ZIF-67 and Zn-ZIF-8 could be mainly attributed to lithiation and delithiation of nitrogen atoms, accompanied by the breakage and recoordination of metal nitrogen bond. Morever, a few metal nitrogen bonds without recoordination will lead to the amorphization of CoZn-ZIF and the formation of few nitrogen radicals.
