Influence of Dowel Center Spacing on Chamfered-Joint Components Made byCupressus funebris Wood

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.

三趾啄木鸟西南亚种(Picoides tridactylus funebris)的取食行为分析(英文)

三趾啄木鸟西南亚种(Picoides tridactylus funebris)是青藏高原的特有鸟类。自从1870年被发现后,未见关于该鸟生活史的报道。在2007年4月至7月,我们对一对三趾啄木鸟西南亚种的取食行为进行了观察研究。通过无线电遥测跟踪,共获得117个取食记录样本,其中28个是雄鸟的,89个是雌鸟的。结果显示,该鸟更加偏好在云杉和枯树上取食,胸径平均为32.7±9.2cm该鸟主要采用啄取的方式进食(39.8%),其次是剥皮(13.2%)。在关于取食基质的4个调查参数中有3个存在差异显著,因此推断该鸟存在雌雄鸟生态位分离现象。这可能与二者喙的性二态有关,雄鸟喙略微大于雌鸟。三趾啄木鸟吸取树汁的比例(4.1%)要高于高山亚种(P.t. alpinus),说明西南亚种的生活环境由于缺乏食物,更加依赖吸食树汁来维持生存。总体来讲,三趾啄木鸟西南亚种的取食行为与其他亚种还是十分相似的。

Growth Performance of Cypress (Cupressus funebris) Trees in Progeny Test Plantations

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.

Marine alkaloids as the chemical marker for the prey–predator relationship of the sponge Xestospongia sp.and the nudibranch Jorunna funebris

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.

水分胁迫和复水对石灰岩地区柏木幼苗根系生长的影响

利用适生植物自身的抗旱能力来进行石灰岩地区植被的恢复和重建是石灰岩生态研究中的重要问题。为了解石灰岩山地适生物种柏木对水分胁迫的适应机制,以柏木实生苗为材料,通过盆栽水分受控实验,研究了其根系生长特性及复水后的修复能力。结果表明:在水分胁迫程度不大、历时不长的情况下,水分胁迫有诱导根系下扎的趋势,复水后,根长在原有的基础上进一步伸长。随着胁迫的加剧和胁迫时间的延长,柏木幼苗的根长、根平均直径、根表面积和根体积等根系大小参数均呈降低趋势,以采取小根系来增强竞争力。复水后,除重度干旱外,其余处理组根系大小参数都能恢复到对照水平,补偿作用与胁迫程度有关。一定程度的水分胁迫对柏木幼苗的茎叶生长没有产生影响,而对根的抑制作用明显,根冠比降低,但胁迫程度加剧和历时延长后,柏木幼苗的根冠比有增大的趋势。柏木幼苗在水分胁迫较轻时把较多的碳水化合物分配到茎叶中,而胁迫严重时把较多的碳水化合物分配到根部。复水促进根、冠干物质的积累,但不同的胁迫程度和胁迫时间促进作用不同。

宜昌市郊不同龄级柏木人工林下植物区系组成变化趋势

对湖北宜昌市郊3个龄级柏木(Cupressus funebris)人工林下植物区系组成进行了研究,结果表明:从幼龄林、中龄林至近熟林阶段,林下植物科属种数量均呈增加趋势,草本植物、灌木和乔木的种数也呈增加趋势,但常绿乔木种几乎没有增加;3个龄级柏木人工林下均以双子叶植物为主,并且种数增加趋势明显,蕨类植物种类增加不多,但趋于在草本层占绝对优势;属的分布型变化趋势为以热带分布属占优势;趋向热带分布属与温带分布属数量接近。