46 resultados para Mitchel, O. M. (Ormsby MacKnight), 1809-1862.

em Chinese Academy of Sciences Institutional Repositories Grid Portal


Relevância:

20.00% 20.00%

Publicador:

Resumo:

A total of 38 Amiota (s. str.) species (about 40% of the world total) are reported from southern China, with descriptions of 23 new species, i.e. sinuata species-group: aculeata Chen and Aotsuka, sp. nov., subsinuata Chen and Aotsuka, sp. nov., xishuangbanna Chen and Aotsuka, sp. nov.; basdeni species-group: brevipartita Chen and Gao, sp. nov., curvispina Chen and Gao, sp. nov., lipingae Chen and Gao, sp. nov., huae Chen and Gao, sp. nov., longispina Chen and Gao, sp. nov.; taurusata species-group: asymmetrica Chen and Takamori, sp. nov.; femorata Chen and Takamori, sp. nov., yixiangensis Chen and Takamori, sp. nov.; alboguttata species-group: ailaoshanensis Chen and Watabe, sp. nov., arcuata Chen and Watabe, sp. nov., dehiscentia Chen and Watabe, sp. nov., jizushanensis Chen and Watabe, sp. nov., latitabula Chen and Watabe, sp. nov., luguhuensis Chen and Watabe, sp. nov., nozawai Chen and Watabe, sp. nov., paraspinata Chen and Watabe, sp. nov., shangrila Chen and Watabe, sp. nov.; and ungrouped: fuscicata Chen and Zhang, sp. nov., wangi Chen and Zhang, sp. nov., wuyishanensis Chen and Zhang, sp. nov. A key to all species from southern China is provided. The Amiota fauna of southern China at the species-group level is compared with that of six geographic regions. The subgenus Amiota is assumed to have originated and produced many species-groups in the Oriental region of East Asia, and then the basdeni, alboguttata and rufescens species-groups might have spread to Europe and North-Central America throughout the Palearctic region of East Asia and both the apodemata, sinuata and nagatai species-groups to tropical regions of South-East Asia.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

瘦尾细额溞是一种出现数量极其稀少的枝角类。关于它的生物学特征尚未见诸文献。本文测量了一次采自云南永胜一池塘的本种300个两性个体的体长和怀卵量,就其幼体与成体的数量、体长与怀卵量、雄性以及性比等问题探讨了种群的生物学状况。 详细观察比较了这个种的重要分类特征——雌体后腹部,并描述了变异范围。对卵鞍和雄体也作了描述。

Relevância:

10.00% 10.00%

Publicador:

Resumo:

采用了改进型Picard迭代差分法求解土壤水分运动的混合型Richards方程,避免了采用Picard迭代法求解h型Richards方程所出现的质量平衡误差问题.同时,采用迎风二次型插值差分法求解土壤盐分运移的对流扩散方程,避免了采用一般差分格式时所出现的数值弥散问题.最后,将上述动力学模型对塔里木盆地绿洲农田在灌既入渗条件下的土壤水盐运动过程进行了数值模拟,模拟结果与测量值吻合较好.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The deformation of alkali metals K, Rb, and Cs under epitaxial deformation is studied via the ab initio pseudopotential plane wave method using the local-density approximation. Under loading from the stable fee phase, metastable stares along directions [001], [111], and [201] are identified. One metastable state, presented at direction [201], has a very low symmetry in contrast to the planes [001] and [201]. Our results show that the softening direction and sequences of growth is significantly affected by the existence of the metastable states and magnitude of the energy barrier. The resulting softening sequences from soft to hard are [201], [110], [001], and [111] under biaxial compression and [001], [111], [201], and [110] under biaxial tension. An orthorhombic deformation path is used to investigate the fact, that the structure of the alkali films K and Cs evolve from the quasihexagonal structure into the (110)-oriented bcc structure, observed by experiments.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

In this paper the photorefractive sensitivity defined for single-centre holographic recording is modified to adapt two-centre holographic recording. Based on the time analytic solution of Kukhtarev equations for doubly doped crystals, the analytical expression of photorefractive sensitivity is given. For comparison with single-centre holographic recording and summing the electron competition effects between the deeper and shallower traps, an effective electron transport length is proposed, which varies with the intensity ratios of recording light to sensitive light. According to analyses in this paper, the lower photorefractive sensitivity in two-centre holographic recording is mainly due to the lower concentration of unionized dopants in the shallower centre and the lower effective electron transport length.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

从德鲁德理论出发,对多元共蒸法镀制的非均匀膜的折射率分布与沉积速率的关系进行了探讨;然后利用计算机辅助模拟,对德鲁德分布非均匀光学薄膜,从单周期和多周期、正变和负变、完整周期和存在半周期几个方面对其光学特性进行了系统分析.研究发现:其透射率的极小值和周期数的关系遵从周期数的三次多项式衰减规律,不同规律的德鲁德分布非均匀膜可用来设计不同功能的滤光片.

Relevância:

10.00% 10.00%

Publicador:

Relevância:

10.00% 10.00%

Publicador:

Relevância:

10.00% 10.00%

Publicador:

Resumo:

首次报道了云南元谋盆地(虎跳滩土林、湾堡土林和新华土林)晚上新世的硅化木材植物群和山西太谷盆地晚上新世的炭屑木材植物群,分析了这两个盆地当时的植被、环境和气候,为认识我国西南地区和北方中部地区晚上新世气候变化提供了生物学证据。 1。云南元谋盆地晚上新世沙沟组(相当于钱方等1991元谋组下部一、二段)化石木植物群包括:裸子植物1种,归属于三尖杉科(Cephalotaxaceae)三尖杉属(Cephalotaxus)或红豆杉科(Taxaceae)穗花杉属(Amentotaxus);被子植物11种,分别归属于楝科(Meliaceae)香椿属(Toona)、大戟科(Euphorbiaceae)秋枫属(Bischofia)、榆科(Ulmaceae)榉属(Zelkova)、豆科(Fabaceae)黄檀属(Dalbergia)、壳斗科(Fagaceae)锥属(Castanopsis)、青冈属(Cyclobalanopsis)、 千屈菜科(Lythraceae)紫薇属(Lagerstroemia)、桑科(Moraceae)桑属(Morus)、胡桃科(Juglandaceae)、豆科和壳斗科。其中三尖杉属或穗花杉属、楝科香椿属、豆科黄檀属、壳斗科锥属、青冈属、千屈菜科紫薇属、桑科桑属、胡桃科和壳斗科的化石木在我国为首次报道。依据植物群的组成,当时该盆地周围山地上的森林是以锥属、青冈属和三尖杉属或穗花杉属为主要分子的常绿针阔混交林,盆地内的树木包括楝科香椿属、大戟科秋枫属、豆科和千屈菜科紫薇属等植物;当时的气候为亚热带气候,温暖湿润。与印度同时代植物群相比,元谋植物群不具有典型的热带雨林分子如龙脑香科植物,而在印度晚第三纪则常见热带雨林分子。这种差异可能是因为中印植物区系起源不同,以及地质历史时期青藏高原的隆升造成区域气候分异,从而导致中印古植物区系不同。 2.山西太谷盆地晚上新世小白组化石木植物群包括榆科(Ulmaceae)榆属(Ulmus)、蔷薇科(Rosaceae)李属(Prunus)和桑科柘属(Cudrania),它们的标本保存为炭屑木材。该化石木群的发现,以及综合通过孢粉学研究得出的古气候研究结果,表明当时当地属于典型的温带气候。化石木清晰的生长轮表明当时气候具明显的季节性。现代生态木材解剖学研究发现温带干旱地区植物群中导管分子壁的螺纹加厚比例较高、且明显。化石木标本导管分子壁具明显的螺纹加厚也表明盆地内为温带的气候类型。孢粉学研究和地层中丰富的石膏层也表明当时气候具有明显的干湿波动,地层中多层炭屑的存在证明了当时气候条件下森林火频繁发生。这些炭屑木材的发现丰富了太谷盆地晚上新世植物群,为古植被重建和古环境恢复提供了新的证据

Relevância:

10.00% 10.00%

Publicador:

Resumo:

China is one of the countries with the greatest diversity of nonhuman primate species: 22 species with 30 subspecies, in 6 genera and 3 families. Primatology in China started in 1862, but fruitful study began only in the 1950s. More than 2,000 academic papers have been published, covering systematics, evolution, ecology, etho-ecology, conservation, reproduction and neuroscience. We review primatology in China over the past century, concentrating mostly on systematics, etho-ecology, conservation and reproduction. We aim to share this information with international colleagues and to seek possibilities for collaboration in the future.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

目的 :在控制水华蓝藻的同时 ,有效利用滇池富营养化水体的水华蓝藻。方法 :藻类资源。以从滇池中收集的水华蓝藻干粉为材料 ,对从水华蓝藻中γ -亚麻酸的含量进行了分析 ,对提取γ -亚麻酸的几个基本参数进行了研究。结果 :直接用萃取溶剂浸泡藻粉 ,并用超声波破碎细胞 ,可以简化操作且增加γ -亚麻酸得率 ;石油醚是比较合适的萃取溶剂 ;进行皂化反应时所用皂化液为 (KOH -CH3CH2 OH -H2 O) ,最适反应温度为 5 0 - 6 0℃ ,γ -亚麻酸酯在氮气保护下进行酸化可以防止游离出来的γ亚

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Sinocrossocheilus was recently diagnosed by Su et al. (2003) as consisting of nine species, i.e. S. bamaensis, S. guizhouensis, S. liuchengensis, S. longibullus, S. tridentis, S. microstomatus, S. nigrovittatus, S. labiatus, and S. papillolabrus. It is actually a catch-all genus that is composed of some species misidentified from Pseudocrossocheilus and Hongshuia. Sinocrossocheilus is here redefined based mainly on the details of the lower lip morphology; it is easily separated from all other Asian Labeonini genera in possessing a lower lip with its median lobe modified into a densely papillated, greatly protruded, crescentic fold and a papillose, slightly protruded, triangular fleshy pad which is posteriorly continuous with the mental region. Two species are recognized in this genus: S. guizhouensis and S. labiatus. Detailed redescriptions are given for the two species. All remaining species do not fit with the new definition of Sinocrossocheilus; six species, i.e. S. papillolabrus, S. nigrovittatus, S. bamaensis, S. longibullus, S. liuchengensis, and S. tridentis, should be moved to Pseudocrossocheilus and S. microstomatus to Hongshuia.