993 resultados para 316.8487
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The Hainan gibbon (Nomascus hainanus) is one of the most endangered primates in the world, confined to mature natural forest in Hainan Island, China. We assessed changes in habitat condition on the island between 1991 and 2008, using vegetation maps generated by remote-sensing images. We defined forest suitable for gibbons based on composition, tree size and canopy cover. During the 17-year period, the area of suitable gibbon forest decreased by 540 km(2) (35%) across the whole island, and by 6.3 km(2) (7%) in the locality of the sole remaining gibbon population at Bawangling National Nature Reserve. The forest patches large enough (>1 km(2)) to support a gibbon group decreased from 754 km(2) to 316 km(2) in total area, and from 92 to 64 in number. Suitable natural forest was mainly replaced by plantations below 760 m, or degraded by logging, grazing and planting of pines above 760 m. Meanwhile, forests in former confirmed gibbon areas became more fragmented: mean area of patches decreased by 53%. We mapped the patches of natural forest in good condition which could potentially support gibbons. We recommend a freeze on further expansion of plantations between core patches at Bawangling, Jiaxi-Houmiling and Yinggeling Nature Reserves in accordance with forest protection regulations; establishment of nature reserves in currently unprotected natural forest patches elsewhere in line with the local government's nature reserve expansion policy; and active natural-forest restoration between remaining fragments at Bawangling. (C) 2010 Elsevier Ltd. All rights reserved.
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国家自然科学基金和云南省自然科学基金资助
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测定了浙江省三个兼用型品种(萧山鸡、白银耳鸡、灵昆鸡)539bp的线粒体DNA D-环区序列,计算了各品种间的遗传距离,构建了各鸡种的聚类关系图。结果显示,三个鸡种之间的遗传差异较小,其中灵昆鸡和白银耳鸡关系较近,萧山鸡与这两种鸡关系较远。从品种外形、形成历史及DNA水平等方面综合考虑,灵昆鸡的母系来源可能就是白银耳鸡。结果还显示,萧山鸡是遗传上变异较大的类群,具丰富的遗传多样性。
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To investigate the karyotypic relationships between Chinese muntjac (Muntiacus reevesi), forest musk deer (Moschus berezovskii) and gayal (Bos frontalis), a complete set of Chinese muntjac chromosome-specific painting probes has been assigned to G-banded chromosomes of these three species. Sixteen autosomal probes (i.e. 6-10, 12-22) of the Chinese muntjac each delineated one pair of conserved segments in the forest musk deer and gayal, respectively. The remaining six autosomal probes (1-5, and 11) each delineated two to five pairs of conserved segments. In total, the 22 autosomal painting probes of Chinese muntjac delineated 33 and 34 conserved chromosomal segments in the genomes of forest musk deer and gayal, respectively. The combined analysis of comparative chromosome painting and G-band comparison reveals that most interspecific homologous segments show a high degree of conservation in G-banding patterns. Eleven chromosome fissions and five chromosome fusions differentiate the karyotypes of Chinese muntjac and forest musk deer; twelve chromosome fissions and six fusions are required to convert the Chinese muntjac karyotype to that of gayal; one chromosome fission and one fusion separate the forest musk deer and gayal. The musk deer has retained a highly conserved karyotype that closely resembles the proposed ancestral pecoran karyotype but shares none of the rearrangements characteristic for the Cervidae and Bovidae. Our results substantiate that chromosomes 1-5 and 11 of Chinese muntjac originated through exclusive centromere-to-telomere fusions of ancestral acrocentric chromosomes. Copyright (C) 2005 S. Karger AG, Basel.
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This work is aimed at optimising the static performance of a high voltage SOI LDMOSFET. Starting with a conventional LDMOSFET, 2D and 3D numerical simulation models, able to accurately match datasheet values, have been developed. Moving from the original device, several design techniques have been investigated with the target of improving the breakdown voltage and the ON-state resistance. The considered design techniques are based on the modification of the doping profile of the drift region and the Superjunction design technique. The paper shows that a single step doping within the drift region is the best design choice for the considered device and is found to give a 24% improvement in the breakdown voltage and a 17% reduction of the ON-state resistance. © 2011 IEEE.
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We analyzed n-mers (n=3-8) in the local environment of 8,249,446 human SNPs and compared their distribution with that in the genome reference sequences. The results revealed that the short sequences, which contained at least one CpG dinucleotide, occurred
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The lack of viable methods to map and label existing infrastructure is one of the engineering grand challenges for the 21st century. For instance, over two thirds of the effort needed to geometrically model even simple infrastructure is spent on manually converting a cloud of points to a 3D model. The result is that few facilities today have a complete record of as-built information and that as-built models are not produced for the vast majority of new construction and retrofit projects. This leads to rework and design changes that can cost up to 10% of the installed costs. Automatically detecting building components could address this challenge. However, existing methods for detecting building components are not view and scale-invariant, or have only been validated in restricted scenarios that require a priori knowledge without considering occlusions. This leads to their constrained applicability in complex civil infrastructure scenes. In this paper, we test a pose-invariant method of labeling existing infrastructure. This method simultaneously detects objects and estimates their poses. It takes advantage of a recent novel formulation for object detection and customizes it to generic civil infrastructure scenes. Our preliminary experiments demonstrate that this method achieves convincing recognition results.
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在20℃、25℃下,将大型溞和老年低额溞分别按7+3(B组),5+5(C组),3+7(D组)的组合进行混合培养,以及用单种培养(10+0(A组),0+10(E组))作为对照,研究了温度和种间竞争对大型溞种群动态和两性生殖的影响笛榻峁砻?在混合培养时,大型溞对老年低额溞产生明显的竞争优势。20℃、25℃下,单种培养的老年低额溞最大种群密度分别为大型溞的2.31和1.97,而在混合培养下老年低额溞的种群密度明显低于大型溞,在实验25d后几乎全部死亡。25℃下两种溞的种群密度之间存在极显著的负相关性(C组:
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试验采用2.5 m×2.5 m围隔,共设置4个试验鱼密度:0、116、176、和316 g/m2,研究了不同密度的鲢对浮游植物的影响。结果表明,仅在无鱼围隔中有大量个体较大的透明溞(Daphnia galeata)产生,并且在无鱼围隔中,浮游植物生物量最低,透明度显著的高于其他的围隔。与其它类似的围隔试验所不同的是:在无鱼围隔中没有蓝藻水华的发生。在有鱼围隔中,浮游甲壳动物始终由个体较小的微型裸腹溞占优势。并且浮游植物的生物量随着鲢密度的升高而降低。浮游植物的种类组成在不同鲢密度的围隔中比较相似,与无鱼围