The traditional tenon and mortise joint has low processing efficiency and a weak theoretical basis,making the structure easy to deform and damage,reducing the safety,and increasing waste of resources.This study aims t...The traditional tenon and mortise joint has low processing efficiency and a weak theoretical basis,making the structure easy to deform and damage,reducing the safety,and increasing waste of resources.This study aims to determine the optimum dowel center spacing parameter for chamfered-joint components and the maximum value of the strength of joints loaded into bending strength and tensile strength.In this study,an integrated opti-mization method combining the single-factor test and one-way ANOVA analysis was proposed to study the influ-ence of the dowel center spacing on the bending strength and the tensile strength of chamfered-joint components made by Cupressus funebris wood.The results revealed that the bending strength of chamfered-joint components decreases linearly with the increase of the dowel center spacing.In addition,the tensile strength of chamfered-joint components increases first and then decreases with the increase of the dowel center spacing,showing para-bola change.The relational expression between dowel center spacing,the bending strength,dowel center spacing and the tensile strength were obtained.展开更多
Based on the 6-year-old young forests of 40 cypress(Cupressus funebris) families from four provenances(Fengdu County, Youyang County and Zhong County of Chongqing City, and Qiandao Lake in Zhejiang Province), differen...Based on the 6-year-old young forests of 40 cypress(Cupressus funebris) families from four provenances(Fengdu County, Youyang County and Zhong County of Chongqing City, and Qiandao Lake in Zhejiang Province), differences in growth traits between families and provenances were studied to select excellent families, so as to provide necessary data support for the upgrading of cypress seed gardens and inferior thinning of seed gardens. The results showed that there were significant differences in tree height, diameter at one meter height, crown width and growth potential between families and provenances. The coefficients of variation among families were 10.25%, 7.19%, 5.91% and 0.98%, respectively, and the coefficients of variation in tree height and diameter at one meter height among provenances were 7.25% and 12.58%, respectively, indicating that the tree height and diameter at one meter height of the superior cypress tree families were rich in variation among families and provenances, and there was potential for high-generation breeding. According to the selection rate of 15%, six excellent families for afforestation(Feng 8, Shi 4, Feng 1, Ye 14, Shi 3, and Ye 6) were screened. The average diameter at one meter height, tree height and crown width of the six excellent families were, respectively, 2.97 cm, 3.39 and 0.78 m, which were 18.82%, 12.70% and 15.42% higher than the family average, respectively, and 15.09%, 9.79% and 15.53% higher than the control group, respectively.展开更多
The dietary relationship study between marine sponge Xestospongia sp.and its nudibranch predators Jorunna funebris based on the discovery of isoquinolinequinones has long been studied.In this study,chemical investigat...The dietary relationship study between marine sponge Xestospongia sp.and its nudibranch predators Jorunna funebris based on the discovery of isoquinolinequinones has long been studied.In this study,chemical investigation of the sponge Xestospongia sp.and nudibranch J.funebris from the South China Sea yielded a new marine alkaloid neopetroside C(1),together with nine known alkaloids(2-10).The chemical structures of all the compounds were elucidated by extensive spectroscopic analysis.Neopetroside C(1)featured a riboside of nicotinic acid with a rareα-N glycosildic linkage and an acyl residue of(Z)-2-methylbut-2-enoic acid attached to C-5′.The plausible chemical ecology relationship between sponge Xestospongia sp.and its nudibranch predator J.funebris was proposed based on the biogenetic relationship of the common marine alkaloids.The observation of two structural fragments,(Z)-2-methylbut-2-enoyloxy and trigonelline groups in both sponge and nudibranch,indicated that nudibranch might uptake chemicals from sponge and then modify and transform them into chemical weapons to defend against predators.展开更多
基金support of the Ministry of Education Humanities and Social Sciences Research Project of China(Grant No.19YJC760009)the Key Research and Development Project of Sichuan Science and Technology Plan Projects(Grant No.2020YFS0357)the Project of Modern Design and Culture Research Centre(Grant No.MD18Z002)。
文摘The traditional tenon and mortise joint has low processing efficiency and a weak theoretical basis,making the structure easy to deform and damage,reducing the safety,and increasing waste of resources.This study aims to determine the optimum dowel center spacing parameter for chamfered-joint components and the maximum value of the strength of joints loaded into bending strength and tensile strength.In this study,an integrated opti-mization method combining the single-factor test and one-way ANOVA analysis was proposed to study the influ-ence of the dowel center spacing on the bending strength and the tensile strength of chamfered-joint components made by Cupressus funebris wood.The results revealed that the bending strength of chamfered-joint components decreases linearly with the increase of the dowel center spacing.In addition,the tensile strength of chamfered-joint components increases first and then decreases with the increase of the dowel center spacing,showing para-bola change.The relational expression between dowel center spacing,the bending strength,dowel center spacing and the tensile strength were obtained.
基金Supported by Assistance Fund for National Seed Base of Forest Tree
文摘Based on the 6-year-old young forests of 40 cypress(Cupressus funebris) families from four provenances(Fengdu County, Youyang County and Zhong County of Chongqing City, and Qiandao Lake in Zhejiang Province), differences in growth traits between families and provenances were studied to select excellent families, so as to provide necessary data support for the upgrading of cypress seed gardens and inferior thinning of seed gardens. The results showed that there were significant differences in tree height, diameter at one meter height, crown width and growth potential between families and provenances. The coefficients of variation among families were 10.25%, 7.19%, 5.91% and 0.98%, respectively, and the coefficients of variation in tree height and diameter at one meter height among provenances were 7.25% and 12.58%, respectively, indicating that the tree height and diameter at one meter height of the superior cypress tree families were rich in variation among families and provenances, and there was potential for high-generation breeding. According to the selection rate of 15%, six excellent families for afforestation(Feng 8, Shi 4, Feng 1, Ye 14, Shi 3, and Ye 6) were screened. The average diameter at one meter height, tree height and crown width of the six excellent families were, respectively, 2.97 cm, 3.39 and 0.78 m, which were 18.82%, 12.70% and 15.42% higher than the family average, respectively, and 15.09%, 9.79% and 15.53% higher than the control group, respectively.
基金This research work was financially supported by the National Natural Science Foundation of China(NSFC)(Nos.8202290170,81991521,42076099,41676073)the NSFC/CNRS joint project(No.81811530284),and the SKLDR/SIMM Project(No.SIMM1903ZZ-04)X-W Li is also thankful for the Shanghai Rising-Star Program(No.20QA1411100),SA-SIBS Scholarship Program.
文摘The dietary relationship study between marine sponge Xestospongia sp.and its nudibranch predators Jorunna funebris based on the discovery of isoquinolinequinones has long been studied.In this study,chemical investigation of the sponge Xestospongia sp.and nudibranch J.funebris from the South China Sea yielded a new marine alkaloid neopetroside C(1),together with nine known alkaloids(2-10).The chemical structures of all the compounds were elucidated by extensive spectroscopic analysis.Neopetroside C(1)featured a riboside of nicotinic acid with a rareα-N glycosildic linkage and an acyl residue of(Z)-2-methylbut-2-enoic acid attached to C-5′.The plausible chemical ecology relationship between sponge Xestospongia sp.and its nudibranch predator J.funebris was proposed based on the biogenetic relationship of the common marine alkaloids.The observation of two structural fragments,(Z)-2-methylbut-2-enoyloxy and trigonelline groups in both sponge and nudibranch,indicated that nudibranch might uptake chemicals from sponge and then modify and transform them into chemical weapons to defend against predators.