Fe/N-based biomass porous carbon composite(Fe/N-p Carbon) was prepared by a facile high-temperature carbonization method from biomass,and the effect of Fe/N-p Carbon on the thermal decomposition of energetic molecular...Fe/N-based biomass porous carbon composite(Fe/N-p Carbon) was prepared by a facile high-temperature carbonization method from biomass,and the effect of Fe/N-p Carbon on the thermal decomposition of energetic molecular perovskite-based material DAP-4 was studied.Biomass porous carbonaceous materials was considered as the micro/nano support layers for in situ deposition of Fe/N precursors.Fe/Np Carbon was prepared simply by the high-temperature carbonization method.It was found that it showed the inherent catalysis properties for thermal decomposition of DAP-4.The heat release of DAP-4/Fe/N-p Carbon by DSC curves tested had increased slightly,compared from DAP-4/Fe/N-p Carbon-0.The decomposition temperature peak of DAP-4 at the presence of Fe/N-p Carbon had reduced by 79°C from384.4°C(pure DAP-4) to 305.4°C(DAP-4/Fe/N-p Carbon-3).The apparent activation energy of DAP-4thermal decomposition also had decreased by 29.1 J/mol.The possible catalytic decomposition mechanism of DAP-4 with Fe/N-p Carbon was proposed.展开更多
With the advancement of agricultural modernization, agricultural machinery service organizations, as an important part of the rural operating entities, show an increasing trend year by year, and need new facilities la...With the advancement of agricultural modernization, agricultural machinery service organizations, as an important part of the rural operating entities, show an increasing trend year by year, and need new facilities land in the process of development and growth. Based on the written survey of 597 agricultural machinery service organizations in Guizhou Province, the demand and demand gap of various facilities land use in agricultural machinery service organizations were analyzed and compared. In addition, based on the field survey and policy background, the main practices and experiences of agricultural machinery service organizations in Guizhou Province in the approval and use of facility land were sorted out, and the problems and causes of large gap in facility agricultural land, lack of standards and difficulty in policy implementation were analyzed. Finally, it recommended that the site selection of agricultural machinery service organization facilities needs to be standardized, the land demand needs to be coordinated, the land scale needs to be scientifically demonstrated, and financial support should be sought to promote Guizhou agricultural machinery service organization to become bigger, better and stronger.展开更多
Tin oxide nanociystals with diameters smaller than 10 nm were synthesized using Na2SnO3 and CO2 as reactants and cetyltrimethylammonium bromide(CTAB) as stabilizer under mild conditions.As a mild acidic gas,CO2 is f...Tin oxide nanociystals with diameters smaller than 10 nm were synthesized using Na2SnO3 and CO2 as reactants and cetyltrimethylammonium bromide(CTAB) as stabilizer under mild conditions.As a mild acidic gas,CO2 is favorable for the accurate adjustment of pH value of Na2SnO3 solution.Stannate salt is stable,cheap and easy in operation.The effects of Na2SnO3concentration,CTAB concentration,aging temperature,and aging time on the nanociystals were studied.It was found that,with the increasing Na2SnO3 concentration,aging temperature and aging time,SnO2 nanociystals size decreases.The formation of SnO2nanociystals can be interpreted by electrostatic-interaction mechanism.SnO2 nanociystals show high photocatalytic activities in the degradation of Rhodamine B solution.The catalytic activity of small nanocrystals is higher than that of large ones.展开更多
Monodispersed dihydrated zinc oxalate(ZnC_2O_4·2H_2O) particles with characteristic morphology were synthesized by aging a mixed solution of zinc nitrate(Zn(NO_3)_2) and sodium oxalate(Na_2C_2O_4) in the presence...Monodispersed dihydrated zinc oxalate(ZnC_2O_4·2H_2O) particles with characteristic morphology were synthesized by aging a mixed solution of zinc nitrate(Zn(NO_3)_2) and sodium oxalate(Na_2C_2O_4) in the presence of a citrate ligand, with an average flat size of approximately 10–15 μm. The important parameters, including the solution pH values and the concentration of the zinc ions and citrate ligand, were investigated using a series of experiments. It is verified that the citrate ligand significantly affects the morphology of zinc oxalate particles, probably via its multiple roles of chelating, dispersing, and selective absorption. Thermodynamic equilibrium of the distribution of zinc species in an aqueous solution of Zn(Ⅱ)-citrate-oxalate-H_2O was estimated to explain the experimental results and to clarify the size and morphological evolution mechanism of the precipitated particles.展开更多
The compound sulforaphane (SFN, 1) has been synthesized via a facile and green synthetic strategy based on the modification of previous methods. Because of its high bioactivities and rare content in nature, the pres...The compound sulforaphane (SFN, 1) has been synthesized via a facile and green synthetic strategy based on the modification of previous methods. Because of its high bioactivities and rare content in nature, the present work is of great important significance.展开更多
(a)NCA polymerization initiated by LiHMDS or other initiators in THF,initiator i)n-hexylamine,ii)HMDS,iii)bipyNi(COD);(b)LiHMDS-initiated open vessel polymerization of BLGNCA at 26 mg and 2 g scale;(c)GPC traces of po...(a)NCA polymerization initiated by LiHMDS or other initiators in THF,initiator i)n-hexylamine,ii)HMDS,iii)bipyNi(COD);(b)LiHMDS-initiated open vessel polymerization of BLGNCA at 26 mg and 2 g scale;(c)GPC traces of poly-BLG at variable DP;(d)Reaction rates of LiHMDS and hexylamine initiated BLGNCA polymerization in THF with NCA:initiator ratio of 100∶1 and initial NCA concentration at 0.2 mol/L;(e)CD spectra of poly-BLG at variable DP prepared from LiHMDS-initiated NCA polymerization.展开更多
4-Amino-4-deoxy-4′-demethylepipodophyllotoxin has been directly synthesized from 4′-demethylepipodophyllotoxin and HN_3 in the presence of BF3·Et_2O,followed by hydrogenation with palladium on charcoal as catal...4-Amino-4-deoxy-4′-demethylepipodophyllotoxin has been directly synthesized from 4′-demethylepipodophyllotoxin and HN_3 in the presence of BF3·Et_2O,followed by hydrogenation with palladium on charcoal as catalyst.展开更多
Heterocyclic ketene aminals 1 react with aryl azides 2 to give the titled compounds 3,and in some cases also with the formation of fused heterocycles 4.
Nitroalkanes react smoothly with CF_3CCl_2COCH=CHPh via Michael addition in the presence of inorganic bases such as KF/Al2O3 or K2CO3, giving fluorinecontaining γ-nitro ketones in good yields.
1. 2-Bispyrroleethylenes can be easily syntnesized bv cc,-,pt}ng pyrrolealdehyde using TiCl_4/Zn as a catalyst. It was found that when the R group is COMe or CO_2 Et, the product is a mixture of trans and cis isomers,...1. 2-Bispyrroleethylenes can be easily syntnesized bv cc,-,pt}ng pyrrolealdehyde using TiCl_4/Zn as a catalyst. It was found that when the R group is COMe or CO_2 Et, the product is a mixture of trans and cis isomers, and in the other cases, the products are pure trans isomers.展开更多
Air-stable cationic organobismuth complexes (2-5) possessing both acidic and basic characters were synthesized. The catalyst system that comprises an air-stable bifunctional Lewis acidic/basic organobismuth complex an...Air-stable cationic organobismuth complexes (2-5) possessing both acidic and basic characters were synthesized. The catalyst system that comprises an air-stable bifunctional Lewis acidic/basic organobismuth complex and [Bmim]BF4 showed high catalytic activity, diastereoselec-tivity, stability, and reusability in the one-pot synthesis of (E)-α,β-unsaturat-ed ketones through highly selective crossed-condensation of ketones and aldehydes. Through switching the reaction from homogeneous to heterogeneous, the system shows facile separation ability and facile reusability.展开更多
Plumbagic acid[β-(2,3-dihydroxybenzoyl)butyric acid](1),has been synthesized from commcrcially available catechol by two facile routes with overall yields of 18.6% and 53.5%,rcspectively.
A facile total synthesis of 6-pentyl-α-pyrone 1 has been described.The key step is the treatment of 2-furyl-pentyl-csrbinol 3 with NBS in aqueous tetrahydrofuran(THF).The overall yield is 34%.
A ffcile tatal synthesis of (±)-selina-3. 11-dien-9-ol (1) has been described. The key step is the onepot reductive fragmentation of α,β-unsaturated p-tosylhydrazone and deduction of 9-carbonyl of 5 With sodium...A ffcile tatal synthesis of (±)-selina-3. 11-dien-9-ol (1) has been described. The key step is the onepot reductive fragmentation of α,β-unsaturated p-tosylhydrazone and deduction of 9-carbonyl of 5 With sodium borohydride.展开更多
In this paper,we report the chemical synthesis of oligonucleotide d-TGGGT using phosphotriester method.The protected pentamer d-MmtTGibGibGibT(=p-ClC6H_4-O(O)P)was deblocked by treatment with concentrated ammonium hyd...In this paper,we report the chemical synthesis of oligonucleotide d-TGGGT using phosphotriester method.The protected pentamer d-MmtTGibGibGibT(=p-ClC6H_4-O(O)P)was deblocked by treatment with concentrated ammonium hydroxide and 80% acetic acid.The pure d-TGGGT obtained by chromatorgraphy on DEAE-Sephadex A-25 and Q-Sepharose FF could be hydrolyzed completely and confirmed by base ratio.展开更多
A convenient method for preparing unsaturated amides via telluro- nium salts employing solid potassium carbonate as a base with high stereo- selectivity in excellent yields has been developed.
s: The convenient synthesis of (-)-5αH.7β 10α-eudesmane-3. 11-dielle 1 has been achieved in four steps starting from R-(-)-carvone. The key step is the reductive deoxygenation of α,β-unsaturated tosylhydrazone to...s: The convenient synthesis of (-)-5αH.7β 10α-eudesmane-3. 11-dielle 1 has been achieved in four steps starting from R-(-)-carvone. The key step is the reductive deoxygenation of α,β-unsaturated tosylhydrazone together with the migration of the double bond.展开更多
基金National Natural Science Foundation of China(Grant No.21975227)the Found of National defence Science and Technology Key Laboratory (Grant No.6142602210306)。
文摘Fe/N-based biomass porous carbon composite(Fe/N-p Carbon) was prepared by a facile high-temperature carbonization method from biomass,and the effect of Fe/N-p Carbon on the thermal decomposition of energetic molecular perovskite-based material DAP-4 was studied.Biomass porous carbonaceous materials was considered as the micro/nano support layers for in situ deposition of Fe/N precursors.Fe/Np Carbon was prepared simply by the high-temperature carbonization method.It was found that it showed the inherent catalysis properties for thermal decomposition of DAP-4.The heat release of DAP-4/Fe/N-p Carbon by DSC curves tested had increased slightly,compared from DAP-4/Fe/N-p Carbon-0.The decomposition temperature peak of DAP-4 at the presence of Fe/N-p Carbon had reduced by 79°C from384.4°C(pure DAP-4) to 305.4°C(DAP-4/Fe/N-p Carbon-3).The apparent activation energy of DAP-4thermal decomposition also had decreased by 29.1 J/mol.The possible catalytic decomposition mechanism of DAP-4 with Fe/N-p Carbon was proposed.
文摘With the advancement of agricultural modernization, agricultural machinery service organizations, as an important part of the rural operating entities, show an increasing trend year by year, and need new facilities land in the process of development and growth. Based on the written survey of 597 agricultural machinery service organizations in Guizhou Province, the demand and demand gap of various facilities land use in agricultural machinery service organizations were analyzed and compared. In addition, based on the field survey and policy background, the main practices and experiences of agricultural machinery service organizations in Guizhou Province in the approval and use of facility land were sorted out, and the problems and causes of large gap in facility agricultural land, lack of standards and difficulty in policy implementation were analyzed. Finally, it recommended that the site selection of agricultural machinery service organization facilities needs to be standardized, the land demand needs to be coordinated, the land scale needs to be scientifically demonstrated, and financial support should be sought to promote Guizhou agricultural machinery service organization to become bigger, better and stronger.
基金Projects (20676016,21076024) supported by the National Natural Science Foundation of China
文摘Tin oxide nanociystals with diameters smaller than 10 nm were synthesized using Na2SnO3 and CO2 as reactants and cetyltrimethylammonium bromide(CTAB) as stabilizer under mild conditions.As a mild acidic gas,CO2 is favorable for the accurate adjustment of pH value of Na2SnO3 solution.Stannate salt is stable,cheap and easy in operation.The effects of Na2SnO3concentration,CTAB concentration,aging temperature,and aging time on the nanociystals were studied.It was found that,with the increasing Na2SnO3 concentration,aging temperature and aging time,SnO2 nanociystals size decreases.The formation of SnO2nanociystals can be interpreted by electrostatic-interaction mechanism.SnO2 nanociystals show high photocatalytic activities in the degradation of Rhodamine B solution.The catalytic activity of small nanocrystals is higher than that of large ones.
文摘Monodispersed dihydrated zinc oxalate(ZnC_2O_4·2H_2O) particles with characteristic morphology were synthesized by aging a mixed solution of zinc nitrate(Zn(NO_3)_2) and sodium oxalate(Na_2C_2O_4) in the presence of a citrate ligand, with an average flat size of approximately 10–15 μm. The important parameters, including the solution pH values and the concentration of the zinc ions and citrate ligand, were investigated using a series of experiments. It is verified that the citrate ligand significantly affects the morphology of zinc oxalate particles, probably via its multiple roles of chelating, dispersing, and selective absorption. Thermodynamic equilibrium of the distribution of zinc species in an aqueous solution of Zn(Ⅱ)-citrate-oxalate-H_2O was estimated to explain the experimental results and to clarify the size and morphological evolution mechanism of the precipitated particles.
基金supported by the National Natural Science Foundation of China(No.20472025 and No.20021001).
文摘The compound sulforaphane (SFN, 1) has been synthesized via a facile and green synthetic strategy based on the modification of previous methods. Because of its high bioactivities and rare content in nature, the present work is of great important significance.
文摘(a)NCA polymerization initiated by LiHMDS or other initiators in THF,initiator i)n-hexylamine,ii)HMDS,iii)bipyNi(COD);(b)LiHMDS-initiated open vessel polymerization of BLGNCA at 26 mg and 2 g scale;(c)GPC traces of poly-BLG at variable DP;(d)Reaction rates of LiHMDS and hexylamine initiated BLGNCA polymerization in THF with NCA:initiator ratio of 100∶1 and initial NCA concentration at 0.2 mol/L;(e)CD spectra of poly-BLG at variable DP prepared from LiHMDS-initiated NCA polymerization.
文摘4-Amino-4-deoxy-4′-demethylepipodophyllotoxin has been directly synthesized from 4′-demethylepipodophyllotoxin and HN_3 in the presence of BF3·Et_2O,followed by hydrogenation with palladium on charcoal as catalyst.
文摘Heterocyclic ketene aminals 1 react with aryl azides 2 to give the titled compounds 3,and in some cases also with the formation of fused heterocycles 4.
文摘Nitroalkanes react smoothly with CF_3CCl_2COCH=CHPh via Michael addition in the presence of inorganic bases such as KF/Al2O3 or K2CO3, giving fluorinecontaining γ-nitro ketones in good yields.
文摘1. 2-Bispyrroleethylenes can be easily syntnesized bv cc,-,pt}ng pyrrolealdehyde using TiCl_4/Zn as a catalyst. It was found that when the R group is COMe or CO_2 Et, the product is a mixture of trans and cis isomers, and in the other cases, the products are pure trans isomers.
文摘Air-stable cationic organobismuth complexes (2-5) possessing both acidic and basic characters were synthesized. The catalyst system that comprises an air-stable bifunctional Lewis acidic/basic organobismuth complex and [Bmim]BF4 showed high catalytic activity, diastereoselec-tivity, stability, and reusability in the one-pot synthesis of (E)-α,β-unsaturat-ed ketones through highly selective crossed-condensation of ketones and aldehydes. Through switching the reaction from homogeneous to heterogeneous, the system shows facile separation ability and facile reusability.
文摘Plumbagic acid[β-(2,3-dihydroxybenzoyl)butyric acid](1),has been synthesized from commcrcially available catechol by two facile routes with overall yields of 18.6% and 53.5%,rcspectively.
文摘A facile total synthesis of 6-pentyl-α-pyrone 1 has been described.The key step is the treatment of 2-furyl-pentyl-csrbinol 3 with NBS in aqueous tetrahydrofuran(THF).The overall yield is 34%.
文摘A ffcile tatal synthesis of (±)-selina-3. 11-dien-9-ol (1) has been described. The key step is the onepot reductive fragmentation of α,β-unsaturated p-tosylhydrazone and deduction of 9-carbonyl of 5 With sodium borohydride.
文摘In this paper,we report the chemical synthesis of oligonucleotide d-TGGGT using phosphotriester method.The protected pentamer d-MmtTGibGibGibT(=p-ClC6H_4-O(O)P)was deblocked by treatment with concentrated ammonium hydroxide and 80% acetic acid.The pure d-TGGGT obtained by chromatorgraphy on DEAE-Sephadex A-25 and Q-Sepharose FF could be hydrolyzed completely and confirmed by base ratio.
文摘A convenient method for preparing unsaturated amides via telluro- nium salts employing solid potassium carbonate as a base with high stereo- selectivity in excellent yields has been developed.
文摘s: The convenient synthesis of (-)-5αH.7β 10α-eudesmane-3. 11-dielle 1 has been achieved in four steps starting from R-(-)-carvone. The key step is the reductive deoxygenation of α,β-unsaturated tosylhydrazone together with the migration of the double bond.