The energy budget and regulating factors were investigated over an estuarine wetland during one year of continuous measurement in 2006.The results show that the seasonal changes of the energy fluxes and Bowen ratio(β...The energy budget and regulating factors were investigated over an estuarine wetland during one year of continuous measurement in 2006.The results show that the seasonal changes of the energy fluxes and Bowen ratio(β) were greatly affected by incoming shortwave radiation and canopy growth.During the non-growing season and early-growing season, sensible heat(H) dominated the energy flux, and β could reach a maximum of 2.5, while during most of the growing season, latent heat dominated the energy flux and β fluctuated from 0.4 to 1.0.The energy budget ratio in growing season was about 0.76, and the value would be higher if heat exchange during tidal flooding was in-cluded.During tidal flooding days, β was slightly higher than that at exposure days in most cases.Vegetation cover seems exert little effect on energy partitioning except in March when the standing dead grass intercepted the incoming radiation that might reach the soil surface and reduce the turbulence between soil and atmosphere, thus suppressing the evaporation from the soil though the soil mositure was high at that time.展开更多
The embryo and endosperm development in Ranalisma rostratum was studied in this paper.The zygote divides by a transverse wall to form basal and apical cells.The larger basal cell undergoes no further division and beco...The embryo and endosperm development in Ranalisma rostratum was studied in this paper.The zygote divides by a transverse wall to form basal and apical cells.The larger basal cell undergoes no further division and becomes the basal suspensor cell.The embryo development conforms to the Caryophyllad type.In the mature seed,the embryo is U shaped and forms the embryonic shoot apex accompanied by one intraseminal leaf.The endosperm development belongs to the Hebolial type.The primary endosperm nucleus (invariably lying in the chalazal part of the embryo sac) divides and forms a large micropylar chamber and a small chalazal chamber.The chalazal endosperm chamber remains uninucleate,and free nuclear divisions occur in the micropylar chamber.Cellularization of the endosperm begins simultaneously from the micropylar and the chalazal ends.The cellularization is related to phragmoplast and cell plate, and does not arise from the free growth wall.Accompanying the embryo development,the endosperm degrades and does not exist in the mature seed.In the proembryo developing stages, the basal suspensor cell and chalazal endosperm cell grow to a considerable size.The nucleus and cytoplasm stain densely.Sometimes, binucleate or trinucleate was observed in both of the two cells.In the laterally concave embryo stage,they begin to degenerate which coincides with the cellularization of the endosperm.They are presumed to participate in the nourishment of the embryo proper in the early stages of embryo development.展开更多
In recent years,scientists have been increasingly interested in the energy embodied in traded goods among countries.In this article,the direct energy intensities in various economic sectors of China were calculated wi...In recent years,scientists have been increasingly interested in the energy embodied in traded goods among countries.In this article,the direct energy intensities in various economic sectors of China were calculated with the data of energy consumption and output value of each sector,and the input-output table was used to estimate the external energy consumption.The total energy intensity of all sectors was then obtained.From the data of international trade,the energy embodied in goods trade of China was estimated for the period of 1994-2001.During this period,the average energy intensity of imported goods was always higher than that of exported ones.As a country with a surplus in international goods trade,China actually imported net embodied energy in the past few years.The net embodied energy imported was at the same magnitude of the imported energy in the form of fossil fuels.展开更多
Nematoda is a metazoan group with extremely high diversity only next to Insecta. Caenorhabditis elegans is now a favorable experimental model animal in modern de-velopmental biology, genetics and genomics studies. How...Nematoda is a metazoan group with extremely high diversity only next to Insecta. Caenorhabditis elegans is now a favorable experimental model animal in modern de-velopmental biology, genetics and genomics studies. However, the phylogeny of Nematoda and the phylogenetic position of the phylum within animal kingdom have long been in debate. Recent molecular phylogenetic studies gave great challenges to the traditional nematode classification. The new phylog-enies not only placed the Nematoda in the Ecdysozoan and divided the phylum into five clades, but also provided new insights into animal molecular identification and phyloge-netic biodiversity studies. The present paper reviews major progress and remaining problems in the current molecular phylogenetic studies of Nematoda, and prospects the devel-opmental tendencies of this field.展开更多
基金Under the auspices of National Natural Science Foundation of China (No. 30870409,40471087)Science and Technology Commission of Shanghai (No. 07DZ12038-2)the Program for New Century Excellent Talents in University (No.NCET-06-0364) funded by the Ministry of Education of China
文摘The energy budget and regulating factors were investigated over an estuarine wetland during one year of continuous measurement in 2006.The results show that the seasonal changes of the energy fluxes and Bowen ratio(β) were greatly affected by incoming shortwave radiation and canopy growth.During the non-growing season and early-growing season, sensible heat(H) dominated the energy flux, and β could reach a maximum of 2.5, while during most of the growing season, latent heat dominated the energy flux and β fluctuated from 0.4 to 1.0.The energy budget ratio in growing season was about 0.76, and the value would be higher if heat exchange during tidal flooding was in-cluded.During tidal flooding days, β was slightly higher than that at exposure days in most cases.Vegetation cover seems exert little effect on energy partitioning except in March when the standing dead grass intercepted the incoming radiation that might reach the soil surface and reduce the turbulence between soil and atmosphere, thus suppressing the evaporation from the soil though the soil mositure was high at that time.
文摘The embryo and endosperm development in Ranalisma rostratum was studied in this paper.The zygote divides by a transverse wall to form basal and apical cells.The larger basal cell undergoes no further division and becomes the basal suspensor cell.The embryo development conforms to the Caryophyllad type.In the mature seed,the embryo is U shaped and forms the embryonic shoot apex accompanied by one intraseminal leaf.The endosperm development belongs to the Hebolial type.The primary endosperm nucleus (invariably lying in the chalazal part of the embryo sac) divides and forms a large micropylar chamber and a small chalazal chamber.The chalazal endosperm chamber remains uninucleate,and free nuclear divisions occur in the micropylar chamber.Cellularization of the endosperm begins simultaneously from the micropylar and the chalazal ends.The cellularization is related to phragmoplast and cell plate, and does not arise from the free growth wall.Accompanying the embryo development,the endosperm degrades and does not exist in the mature seed.In the proembryo developing stages, the basal suspensor cell and chalazal endosperm cell grow to a considerable size.The nucleus and cytoplasm stain densely.Sometimes, binucleate or trinucleate was observed in both of the two cells.In the laterally concave embryo stage,they begin to degenerate which coincides with the cellularization of the endosperm.They are presumed to participate in the nourishment of the embryo proper in the early stages of embryo development.
基金supported by NSFC (Grant no.70703008)Key Projects of Philosophy and Social Sciences Research of Chinese Ministry of Education (Grant no.07JZD0008)
文摘In recent years,scientists have been increasingly interested in the energy embodied in traded goods among countries.In this article,the direct energy intensities in various economic sectors of China were calculated with the data of energy consumption and output value of each sector,and the input-output table was used to estimate the external energy consumption.The total energy intensity of all sectors was then obtained.From the data of international trade,the energy embodied in goods trade of China was estimated for the period of 1994-2001.During this period,the average energy intensity of imported goods was always higher than that of exported ones.As a country with a surplus in international goods trade,China actually imported net embodied energy in the past few years.The net embodied energy imported was at the same magnitude of the imported energy in the form of fossil fuels.
基金This work was supported by the National Natural Science Foundation of China (Grant No. 30000020) the doctoral Foundation of Shanghai.
文摘Nematoda is a metazoan group with extremely high diversity only next to Insecta. Caenorhabditis elegans is now a favorable experimental model animal in modern de-velopmental biology, genetics and genomics studies. However, the phylogeny of Nematoda and the phylogenetic position of the phylum within animal kingdom have long been in debate. Recent molecular phylogenetic studies gave great challenges to the traditional nematode classification. The new phylog-enies not only placed the Nematoda in the Ecdysozoan and divided the phylum into five clades, but also provided new insights into animal molecular identification and phyloge-netic biodiversity studies. The present paper reviews major progress and remaining problems in the current molecular phylogenetic studies of Nematoda, and prospects the devel-opmental tendencies of this field.
