Urban agglomerations,representing a high-level organizational form of urbanization,play an increasingly vital role in promoting sustainable development.These regions attract substantial population inflows due to their...Urban agglomerations,representing a high-level organizational form of urbanization,play an increasingly vital role in promoting sustainable development.These regions attract substantial population inflows due to their robust economic foundations and advanced public service facilities.To assess this dynamic,an evaluation index system for urban sustainable development goals(SDGs)was constructed based on the United Nations SDGs framework.Using three representative urban agglomerations of Beijing-Tianjin-Hebei(BTH),Yangtze River Delta(YRD),and Chengdu-Chongqing(CY)in China as case studies,this research explores the realization of SDGs since the construction of the urban agglomerations and its coupling with population changes by combining multifactorial analysis and the coupling coordination degree model.Results reveal that SDG scores in these cities have increased by an average of 25.33%since 2005.Scores in central cities are significantly higher than the average,and the gap between cities is narrowing.However,there are still trade-offs among some of the goals.Additionally,the process of SDGs realization in core cities with large populations is largely coordinated with population growth.The findings provide a reference for urban agglomerations to adopt cross-regional collaborative governance measures to achieve the SDGs.展开更多
Sperm nuclear expansion, meiosis and the association of the male and female pronuclei leading to the four-cell stage in normal Chlamys farreri eggs were observed under a fluorescence microscope. The effects of ultravi...Sperm nuclear expansion, meiosis and the association of the male and female pronuclei leading to the four-cell stage in normal Chlamys farreri eggs were observed under a fluorescence microscope. The effects of ultraviolet (UV) irradiation on the fer- tilizing sperm were also examined. Both normal and UV-irradiated sperm nuclei enlarged at three distinct phases (phase A, meta- phase I; phase B, polar body formation; and phase C, female pronuclear development and expansion) that were temporally correlated with meiotic process of the maternal chromosomes. Sperm nuclei underwent a rapid, initial enlargement during phase A, but con- densed slightly during phase B, then re-enlarged during phase C. The effects of UV irradiation were not apparent during transforma- tion of the sperm nucleus into a male pronucleus, and there was not any apparent effect on meiotic maturation and development of the female pronucleus. However, the rate of expansion of the UV-irradiated sperm nuclei and the size of male pronuclei were reduced apparently. Unlike the female pronucleus, the male pronucleus derived from sperm genome inactivated by UV irradiation did not form chromosomes, but became a dense chromatin body (DCB). At mitotic anaphase, DCB did not participate in the karyokinesis of the first cleavage as evidenced by chromosomal nondisjunction, demonstrating the effectiveness of using UV irradiation to induce gynogenetic scallop embryos.展开更多
基金National Natural Science Foundation of China,No.32471745。
文摘Urban agglomerations,representing a high-level organizational form of urbanization,play an increasingly vital role in promoting sustainable development.These regions attract substantial population inflows due to their robust economic foundations and advanced public service facilities.To assess this dynamic,an evaluation index system for urban sustainable development goals(SDGs)was constructed based on the United Nations SDGs framework.Using three representative urban agglomerations of Beijing-Tianjin-Hebei(BTH),Yangtze River Delta(YRD),and Chengdu-Chongqing(CY)in China as case studies,this research explores the realization of SDGs since the construction of the urban agglomerations and its coupling with population changes by combining multifactorial analysis and the coupling coordination degree model.Results reveal that SDG scores in these cities have increased by an average of 25.33%since 2005.Scores in central cities are significantly higher than the average,and the gap between cities is narrowing.However,there are still trade-offs among some of the goals.Additionally,the process of SDGs realization in core cities with large populations is largely coordinated with population growth.The findings provide a reference for urban agglomerations to adopt cross-regional collaborative governance measures to achieve the SDGs.
基金supported by grants from the National Natural Science Foundation of China(No.30170735)the Cultivation Fund of the Key Scientific and Technical Innovation Project,Ministry of Education of China(No.70741)
文摘Sperm nuclear expansion, meiosis and the association of the male and female pronuclei leading to the four-cell stage in normal Chlamys farreri eggs were observed under a fluorescence microscope. The effects of ultraviolet (UV) irradiation on the fer- tilizing sperm were also examined. Both normal and UV-irradiated sperm nuclei enlarged at three distinct phases (phase A, meta- phase I; phase B, polar body formation; and phase C, female pronuclear development and expansion) that were temporally correlated with meiotic process of the maternal chromosomes. Sperm nuclei underwent a rapid, initial enlargement during phase A, but con- densed slightly during phase B, then re-enlarged during phase C. The effects of UV irradiation were not apparent during transforma- tion of the sperm nucleus into a male pronucleus, and there was not any apparent effect on meiotic maturation and development of the female pronucleus. However, the rate of expansion of the UV-irradiated sperm nuclei and the size of male pronuclei were reduced apparently. Unlike the female pronucleus, the male pronucleus derived from sperm genome inactivated by UV irradiation did not form chromosomes, but became a dense chromatin body (DCB). At mitotic anaphase, DCB did not participate in the karyokinesis of the first cleavage as evidenced by chromosomal nondisjunction, demonstrating the effectiveness of using UV irradiation to induce gynogenetic scallop embryos.
