The geometries of the reactants, transition states, intermediates and products for the titled reactions are optimized with CAS(17,13)/cc pVDZ, CAS(9,7)+1+2/cc pVDZ and CAS(9,7)+1+2/cc pVTZ. All stationary points are c...The geometries of the reactants, transition states, intermediates and products for the titled reactions are optimized with CAS(17,13)/cc pVDZ, CAS(9,7)+1+2/cc pVDZ and CAS(9,7)+1+2/cc pVTZ. All stationary points are characterized with vibrational analysis, and the rate constants for the titled reaction are computed with transition state theory. The obtained values are in good agreement with the experimental ones.展开更多
Using the closed chamber technique, the in situ measurements of N2O and CH4 fluxes was conducted in a broad-leaved Korean pine mixed forest ecosystem in Changbai Mountain, China. from June 1994 to october 1995. The re...Using the closed chamber technique, the in situ measurements of N2O and CH4 fluxes was conducted in a broad-leaved Korean pine mixed forest ecosystem in Changbai Mountain, China. from June 1994 to october 1995. The relationships between fluxes (N2O and CH4) and some major environmental factors (temperature, soil water content and soil availabIe nitrogen) were studied. A significant positive correlation between Nzo emission and air/soil temperature was observed, but no significant correIation was found between N2O emission and soil water content (SWC). This result showed that temperature was an important controlling factor of N2O flux. There was a significant correlation between CH4 uptake and SWC, but no significant correlation was found between CH4 uptake and temperature. This suggested SWC was an important factor controlling CH4 uptake. The very significant negative correlation between logarithmic N2O flux and soil nitrate concentration, significant negative correlation between CH4 flux and soil ammonium content were also found.展开更多
Using stat ic chamber technique, fluxes of CO 2 , CH 4 and N 2 O were measured in the alpine grassland area from July 2000 to July 2001, d eterminations of mean fluxes showed that CO 2 and N 2 O were gene rally releas...Using stat ic chamber technique, fluxes of CO 2 , CH 4 and N 2 O were measured in the alpine grassland area from July 2000 to July 2001, d eterminations of mean fluxes showed that CO 2 and N 2 O were gene rally released from the soil, while the alpine grassland accounted for a weak CH 4 sink. Fluxes of CO 2 , CH 4 and N 2 O ranged widely. The highest CO 2 emission occurred in August, whereas a lmost 90% of the whole year emission occurred in the growing season. But the variations of CH 4 and N 2 O fluxes did not show any clear patterns over the one-year-experim ent. During a daily variation, the maximum CO 2 emission occurred at 16:00, and then decreased to the minimum emi ssion in the early morning. Daily pattern analyses indicated that the variation in CO 2 fluxes was positively related to air temperatures (R 2 =0.73) and soil temperatures at a depth of 5 cm (R 2 =0.86), whereas daily variations in CH 4 and N 2 O fluxes were poorly explained by soil temperatures and climatic va riables. CO 2 emissions in this area were much lower than other grasslands in plain areas .展开更多
This study aimed to investigate the effect of economic growth, agricultural growth and energy use on methane (CH<sub>4</sub>) and nitrous oxide (N<sub>2</sub>O) emissions in Sudan. Within the c...This study aimed to investigate the effect of economic growth, agricultural growth and energy use on methane (CH<sub>4</sub>) and nitrous oxide (N<sub>2</sub>O) emissions in Sudan. Within the context of the EKC, the study applies the OLS, cointegration, vector error correction modelling (VECM) and Granger causality methods. The study has established a long run equilibrium relationship for both CH<sub>4</sub> and N<sub>2</sub>O in their relation to economic growth, agricultural growth and energy use in presence of trade openness (TOP) and inflows of foreign direct investments (FDI). The estimated VECM shows that emissions of CH<sub>4</sub> are significantly affected by economic growth, TOP, and FDI with no effect of agricultural growth in the short run while CH<sub>4</sub> is found to be significantly affected by economic growth, agricultural growth, TOP and FDI in the long run. The estimated VECM for N<sub>2</sub>O shows that N<sub>2</sub>O emissions are more significantly affected by energy use, agricultural growth and FDI with no effect of economic growth in the short run, while N<sub>2</sub>O is found to be significantly affected by economic growth, agricultural growth, TOP and FDI in the long run. Consistently, findings from the estimated OLS and VECMs show that the EKC does not hold for either CH<sub>4</sub>, or N<sub>2</sub>O emissions, and that N<sub>2</sub>O emissions are more significantly affected by economic growth, agricultural growth and energy use than emissions of CH<sub>4</sub>. Findings from impulse response and variance decomposition analysis confirm that emissions of N<sub>2</sub>O are more responsive to economic growth, agricultural growth and energy use than emissions of CH<sub>4</sub>. Granger causality analysis shows existence of bidirectional relationship between CH<sub>4</sub> and agricultural growth, but a unidirectional relationship from CH<sub>4</sub> to FDI. For N<sub>2</sub>O, the study finds a unidirectional relationship running from agricultural growth to N<sub>2</sub>O, while N<sub>2</sub>O emissions are found to cause GDP per capita, the squared GDP per capita, OIL consumption and FDI. In terms of causality, these results suggest that emissions of CH<sub>4</sub> and N<sub>2</sub>O have been generated more by agricultural activities than by overall economic activity, and that activities generating N<sub>2</sub>O emissions in particular have been contributing significantly to economic growth. Within the context of the country’s intended nationally determined contributions, the findings of this study suggest that policies should be directed cautiously but more effectively to control N<sub>2</sub>O than CH<sub>4</sub> emissions. Economic growth could be pursued without significant environmental harm from both CH<sub>4</sub> and N<sub>2</sub>O emissions. However, Sudan should expand adoption of energy efficiency measures, expansion of renewable energy use, place restrictions on production and use of fuel woods and charcoal for low carbon economy and green growth.展开更多
The crystal structure of the title complex, [NiL], has been determined by using X-ray analysis (H2L = 2,3-dioxo-5,6:13,14-dibenzo-7,12-bis(methoxycarbonyl)-1,4,8,11-tetraazacyclotetra- deca-7,11-diene). Crystal data: ...The crystal structure of the title complex, [NiL], has been determined by using X-ray analysis (H2L = 2,3-dioxo-5,6:13,14-dibenzo-7,12-bis(methoxycarbonyl)-1,4,8,11-tetraazacyclotetra- deca-7,11-diene). Crystal data: C22H18N4O6Ni, Mr = 493.11, triclinic, space group P, a = 9.128(6), b = 9.941(7), c = 12.396(8) ? a = 107.11(1), b = 106.14(1), g = 97.69(1), V = 1003.9(11) 3, Z = 2, Dc = 1.631 g/cm3, m(MoKa) = 1.018 mm-1, F(000) = 508, R = 0.0584 and wR = 0.0981 for 1724 observed reflections with I > 2s(I). The Ni(II) atom is coordinated by four nitrogen donors of the macrocyclic ligand with a slightly distorted square-planar geometry. In the crystal, the CH…O hydrogen bonds link the complex molecules to form infinite 1D chains which are further linked by p…p stacking interactions to form chain-pairs.展开更多
文摘The geometries of the reactants, transition states, intermediates and products for the titled reactions are optimized with CAS(17,13)/cc pVDZ, CAS(9,7)+1+2/cc pVDZ and CAS(9,7)+1+2/cc pVTZ. All stationary points are characterized with vibrational analysis, and the rate constants for the titled reaction are computed with transition state theory. The obtained values are in good agreement with the experimental ones.
文摘Using the closed chamber technique, the in situ measurements of N2O and CH4 fluxes was conducted in a broad-leaved Korean pine mixed forest ecosystem in Changbai Mountain, China. from June 1994 to october 1995. The relationships between fluxes (N2O and CH4) and some major environmental factors (temperature, soil water content and soil availabIe nitrogen) were studied. A significant positive correlation between Nzo emission and air/soil temperature was observed, but no significant correIation was found between N2O emission and soil water content (SWC). This result showed that temperature was an important controlling factor of N2O flux. There was a significant correlation between CH4 uptake and SWC, but no significant correlation was found between CH4 uptake and temperature. This suggested SWC was an important factor controlling CH4 uptake. The very significant negative correlation between logarithmic N2O flux and soil nitrate concentration, significant negative correlation between CH4 flux and soil ammonium content were also found.
基金National Key Project for Basic Research,No.G1998040800
文摘Using stat ic chamber technique, fluxes of CO 2 , CH 4 and N 2 O were measured in the alpine grassland area from July 2000 to July 2001, d eterminations of mean fluxes showed that CO 2 and N 2 O were gene rally released from the soil, while the alpine grassland accounted for a weak CH 4 sink. Fluxes of CO 2 , CH 4 and N 2 O ranged widely. The highest CO 2 emission occurred in August, whereas a lmost 90% of the whole year emission occurred in the growing season. But the variations of CH 4 and N 2 O fluxes did not show any clear patterns over the one-year-experim ent. During a daily variation, the maximum CO 2 emission occurred at 16:00, and then decreased to the minimum emi ssion in the early morning. Daily pattern analyses indicated that the variation in CO 2 fluxes was positively related to air temperatures (R 2 =0.73) and soil temperatures at a depth of 5 cm (R 2 =0.86), whereas daily variations in CH 4 and N 2 O fluxes were poorly explained by soil temperatures and climatic va riables. CO 2 emissions in this area were much lower than other grasslands in plain areas .
文摘This study aimed to investigate the effect of economic growth, agricultural growth and energy use on methane (CH<sub>4</sub>) and nitrous oxide (N<sub>2</sub>O) emissions in Sudan. Within the context of the EKC, the study applies the OLS, cointegration, vector error correction modelling (VECM) and Granger causality methods. The study has established a long run equilibrium relationship for both CH<sub>4</sub> and N<sub>2</sub>O in their relation to economic growth, agricultural growth and energy use in presence of trade openness (TOP) and inflows of foreign direct investments (FDI). The estimated VECM shows that emissions of CH<sub>4</sub> are significantly affected by economic growth, TOP, and FDI with no effect of agricultural growth in the short run while CH<sub>4</sub> is found to be significantly affected by economic growth, agricultural growth, TOP and FDI in the long run. The estimated VECM for N<sub>2</sub>O shows that N<sub>2</sub>O emissions are more significantly affected by energy use, agricultural growth and FDI with no effect of economic growth in the short run, while N<sub>2</sub>O is found to be significantly affected by economic growth, agricultural growth, TOP and FDI in the long run. Consistently, findings from the estimated OLS and VECMs show that the EKC does not hold for either CH<sub>4</sub>, or N<sub>2</sub>O emissions, and that N<sub>2</sub>O emissions are more significantly affected by economic growth, agricultural growth and energy use than emissions of CH<sub>4</sub>. Findings from impulse response and variance decomposition analysis confirm that emissions of N<sub>2</sub>O are more responsive to economic growth, agricultural growth and energy use than emissions of CH<sub>4</sub>. Granger causality analysis shows existence of bidirectional relationship between CH<sub>4</sub> and agricultural growth, but a unidirectional relationship from CH<sub>4</sub> to FDI. For N<sub>2</sub>O, the study finds a unidirectional relationship running from agricultural growth to N<sub>2</sub>O, while N<sub>2</sub>O emissions are found to cause GDP per capita, the squared GDP per capita, OIL consumption and FDI. In terms of causality, these results suggest that emissions of CH<sub>4</sub> and N<sub>2</sub>O have been generated more by agricultural activities than by overall economic activity, and that activities generating N<sub>2</sub>O emissions in particular have been contributing significantly to economic growth. Within the context of the country’s intended nationally determined contributions, the findings of this study suggest that policies should be directed cautiously but more effectively to control N<sub>2</sub>O than CH<sub>4</sub> emissions. Economic growth could be pursued without significant environmental harm from both CH<sub>4</sub> and N<sub>2</sub>O emissions. However, Sudan should expand adoption of energy efficiency measures, expansion of renewable energy use, place restrictions on production and use of fuel woods and charcoal for low carbon economy and green growth.
基金This work was supported by the National Natural Science Foundation of China (20071019, 50172021 and 90101028)
文摘The crystal structure of the title complex, [NiL], has been determined by using X-ray analysis (H2L = 2,3-dioxo-5,6:13,14-dibenzo-7,12-bis(methoxycarbonyl)-1,4,8,11-tetraazacyclotetra- deca-7,11-diene). Crystal data: C22H18N4O6Ni, Mr = 493.11, triclinic, space group P, a = 9.128(6), b = 9.941(7), c = 12.396(8) ? a = 107.11(1), b = 106.14(1), g = 97.69(1), V = 1003.9(11) 3, Z = 2, Dc = 1.631 g/cm3, m(MoKa) = 1.018 mm-1, F(000) = 508, R = 0.0584 and wR = 0.0981 for 1724 observed reflections with I > 2s(I). The Ni(II) atom is coordinated by four nitrogen donors of the macrocyclic ligand with a slightly distorted square-planar geometry. In the crystal, the CH…O hydrogen bonds link the complex molecules to form infinite 1D chains which are further linked by p…p stacking interactions to form chain-pairs.
