Triploid carp(100%)with 150(3n=150)chromosomes were obtained by crossing the females of improved tetraploid hybrids(♀, 4n=200)of red crucian carp(♀)×common carp(♂)with the males of diploid yellow river carp(♂...Triploid carp(100%)with 150(3n=150)chromosomes were obtained by crossing the females of improved tetraploid hybrids(♀, 4n=200)of red crucian carp(♀)×common carp(♂)with the males of diploid yellow river carp(♂,2n=100).The crosses yielded transgenic triploid carp(positive triploid fish,44.2%of the progeny)and non-transgenic triploid carp(negative triploid fish). Histological examination of the gonads of 24-month-old positive triploid fish suggested they were sterile and the fish were not able to produce mature gametes during the breeding season.Morphologically,both the positive and negative triploid fish were similar.They had a spindle-shaped,laterally compressed,steel grey body with two pairs of barbells.Most of the quantifiable traits of the triploid carp were intermediate between those of the two parents.The positive and negative triploid fish were raised in the same pond for 2 years.The mean body weight of the positive triploid fish was 2.3 times higher than the negative triploid fish.The weight of the largest positive triploid fish was 2.91 times higher than that of the largest negative triploid fish.Thus,we produced fast-growing transgenic triploid carp that have a reduced ecological risk because of their inability to mate and produce progeny.展开更多
Given the background of a transmission tower erected on a particular mining subsidence area,we used finite element modeling to analyze the anti-deformation performance of transmission towers under a number of differen...Given the background of a transmission tower erected on a particular mining subsidence area,we used finite element modeling to analyze the anti-deformation performance of transmission towers under a number of different load conditions,including horizontal foundation displacement,uneven vertical downward displacement,wind loads and icing conditions.The results show that the failure in stability of a single steel angle iron represents the limit of the tower given ground deformation.We calculated the corresponding limits of foundation displacements.The results indicate that compression displacement of the foundation is more dangerous than tension displacement.Under complex foundation displacement conditions,horizontal foundation displacement is a key factor leading to failure in the stability of towers.Under conditions of compression or tension displacement of the foundation,wind load becomes the key factor.Towers do not fail when foundation displacements are smaller than 1% (under tension) or 0.5% (under horizontal compression or single foundation subsidence) of the distance between two supports.展开更多
基金supported by the National Key Basic Research Program of China (2007CB109206)the National Special Fund for Research in Public Welfare Sector (200903046-08)
文摘Triploid carp(100%)with 150(3n=150)chromosomes were obtained by crossing the females of improved tetraploid hybrids(♀, 4n=200)of red crucian carp(♀)×common carp(♂)with the males of diploid yellow river carp(♂,2n=100).The crosses yielded transgenic triploid carp(positive triploid fish,44.2%of the progeny)and non-transgenic triploid carp(negative triploid fish). Histological examination of the gonads of 24-month-old positive triploid fish suggested they were sterile and the fish were not able to produce mature gametes during the breeding season.Morphologically,both the positive and negative triploid fish were similar.They had a spindle-shaped,laterally compressed,steel grey body with two pairs of barbells.Most of the quantifiable traits of the triploid carp were intermediate between those of the two parents.The positive and negative triploid fish were raised in the same pond for 2 years.The mean body weight of the positive triploid fish was 2.3 times higher than the negative triploid fish.The weight of the largest positive triploid fish was 2.91 times higher than that of the largest negative triploid fish.Thus,we produced fast-growing transgenic triploid carp that have a reduced ecological risk because of their inability to mate and produce progeny.
基金National Natural Science Foundation of China(No.50004008)Xuzhou Power Supply Company and the Fundamental Research Funds for the Central Universities(No.2011QNB18) for their financial and technical support for this work
文摘Given the background of a transmission tower erected on a particular mining subsidence area,we used finite element modeling to analyze the anti-deformation performance of transmission towers under a number of different load conditions,including horizontal foundation displacement,uneven vertical downward displacement,wind loads and icing conditions.The results show that the failure in stability of a single steel angle iron represents the limit of the tower given ground deformation.We calculated the corresponding limits of foundation displacements.The results indicate that compression displacement of the foundation is more dangerous than tension displacement.Under complex foundation displacement conditions,horizontal foundation displacement is a key factor leading to failure in the stability of towers.Under conditions of compression or tension displacement of the foundation,wind load becomes the key factor.Towers do not fail when foundation displacements are smaller than 1% (under tension) or 0.5% (under horizontal compression or single foundation subsidence) of the distance between two supports.
