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Amniocentesis at 17 weeks' gestation revealed a mosaic karyotype—46,XX/46,XX, — 14,+dic(14)(p11). No abnormalities were detected on ultrasound. Growth and placentation were normal. The fetus was examined after termination of pregnancy and micrognathia and pulmonary hyperlobation were the only abnormalities detected. Several tissues were set up for cytogenetics, including fetal skin, kidney, ovary, and placenta. The diagnosis was confirmed by these studies. The level of mosaicism varied between tissues, with the trisomy 14 cell line highest in amniotic fluid.  相似文献   
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Fire influences the distribution of fauna in terrestrial biomes throughout the world. Use of fire to achieve a mosaic of vegetation in different stages of succession after burning (i.e., patch‐mosaic burning) is a dominant conservation practice in many regions. Despite this, knowledge of how the spatial attributes of vegetation mosaics created by fire affect fauna is extremely scarce, and it is unclear what kind of mosaic land managers should aim to achieve. We selected 28 landscapes (each 12.6 km2) that varied in the spatial extent and diversity of vegetation succession after fire in a 104,000 km2 area in the semiarid region of southeastern Australia. We surveyed for reptiles at 280 sites nested within the 28 landscapes. The landscape‐level occurrence of 9 of the 22 species modeled was associated with the spatial extent of vegetation age classes created by fire. Biogeographic context and the extent of a vegetation type influenced 7 and 4 species, respectively. No species were associated with the diversity of vegetation ages within a landscape. Negative relations between reptile occurrence and both extent of recently burned vegetation (≤10 years postfire, n = 6) and long unburned vegetation (>35 years postfire, n = 4) suggested that a coarse‐grained mosaic of areas (e.g. >1000 ha) of midsuccessional vegetation (11–35 years postfire) may support the fire‐sensitive reptile species we modeled. This age class coincides with a peak in spinifex cover, a keystone structure for reptiles in semiarid and arid Australia. Maintaining over the long term a coarse‐grained mosaic of large areas of midsuccessional vegetation in mallee ecosystems will need to be balanced against the short‐term negative effects of large fires on many reptile species and a documented preference by species from other taxonomic groups, particularly birds, for older vegetation. Mosaicos de Fuego y la Conservación de Reptiles en una Región Propensa al Fuego  相似文献   
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通过对国内外数据元标准化研究现状的分析,以探索实现作业场所职业危害信息系统相关数据元标准化为前提,实现作业场所职业危害信息系统数据共享及发布为目的,指出传统基于数据集共享模式存在的统一性共享性差的问题,研究建立基于数据元和数据集相结合的标准化技术路线,并结合作业场所职业危害用人单位相关数据元采集、提取及标准化过程进行应用和示范,实现不同作业场所职业危害信息系统间相关数据共享。  相似文献   
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Abstract: We explored the impact of forest conversion to agricultural mosaic on anuran, lizard, snake, and turtle assemblages of Neotropical dry forests. Over 2 years, we sampled 6 small watersheds on the west coast of Mexico, 3 conserved and 3 disturbed. The disturbed watersheds were characterized by a mosaic of pastures and cultivated fields (corn, beans, squash) intermingled with patches of different successional stages of dry forest. In each watershed, we conducted 11 diurnal and nocturnal time‐constrained searches in 10 randomly established plots. We considered vulnerability traits of species in relation to habitat modification. Eighteen anuran, 18 lizard, 23 snake, and 3 turtle species were recorded. Thirty‐six species (58%) occurred in both forest conditions, and 14 (22%) and 12 species (19%) occurred only in the conserved and disturbed sites, respectively. Assemblages responded differently to disturbance. Species richness, diversity, and abundance of lizards were higher in disturbed forests. Anuran diversity and species richness were lower in disturbed forest but abundance was similar in both forest conditions. Diversity, richness, and abundance of turtles were lower in disturbed forest. The structure and composition of snake assemblages did not differ between forest conditions. We considered species disturbance sensitive if their abundance was significantly less in disturbed areas. Four anuran (22%), 2 lizard (11%), and 3 turtle (100%) species were sensitive to disturbance. No snake species was sensitive. The decline in abundance of disturbance‐sensitive species was associated with the reduction of forest canopy cover, woody stem cover, roots, and litter‐layer ground cover. Anuran species with small body size and direct embryonic development were especially sensitive to forest disturbance. An important goal for the conservation of herpetofauna should be the determination of species traits associated with extinction or persistence in agricultural mosaics.  相似文献   
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The spatiotemporal structure of the muskrat population has been studied by means of the prenatal radioactive marking of juveniles with 45 Ca and their subsequent recapture in the test area. The muskrat population is characterized by a cyclic type of spatial structure, with seasonal transition from a mosaic type of settling to a diffuse type and, after the breeding season, vice versa.  相似文献   
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长江口湿地景观镶嵌结构演变的数量特征与分形分析   总被引:3,自引:0,他引:3  
鉴于国内湿地研究对象大多为块状湿地。而对狭长形湿地鲜有研究,本文利用1990年和2003年遥感影像作为基本信息源。在GIS技术支持下。选取长江口狭长湿地,建立长江口湿地植被空间数据库。选取斑块大小、分维数、景观破碎度、景观多样性和优势度等指标,研究区域景观的数量特征动态变化;运用分形理论建立各种景观类型形态的分形结构模型,以分维数为依据分析各种景观形态的复杂性;探讨控制和影响区域景观格局的主要因素。结果显示,1990—2003年期间,在自然与人为双重因素作用下该地区的湿地景观发生了显著变化,景观趋于破碎化。植物群落的演替由于人为的原因加速,一些地区景观呈自然变化趋势。一些地区由于围垦的原因。人为扰动大。呈现衰退趋势。  相似文献   
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GPM卫星降水数据在天山山区的适用性分析   总被引:8,自引:1,他引:7  
金晓龙  邵华  张弛  艳燕 《自然资源学报》2016,31(12):2074-2085
卫星降水产品在山区的适用性具有较高的不确定性。论文基于天山山区2014-2015年167个气象站点数据,应用较为广泛的两套卫星降水产品--TRMM与CMORPH,选用均方根误差(RMSE)、相关系数(R)、相对误差(PB),以及分类统计分析指标(错报率FAR、探测率POD、公正先兆评分ETS、频率偏差BIAS)等,评估了新一代卫星降水产品--Global Precipitation Measurement(GPM)在天山山区的适用性。结果表明:相对于以上两种产品,GPM在山区的精度最高。具体表现在:1)3套产品在降水较多的夏秋季均表现较好,相对于TRMM与CMORPH,GPM与观测数据的相关系数最高(R≥0.6),相对误差最小(PB≈10%);2)在整个天山山区,GPM相对于其他两套产品表现出较低的误差范围(-55%~55%);3)GPM在不同的高程带内,均表现出同观测站点较低的误差与较高的相关系数;4)3套降水产品均表现出对探测弱降水事件较高的准确性(POD≈0.58)和较低的错误率(FAR≈0.63),但综合分析4种指数,GPM表现最佳,能够以较准确的精度和较低的误差估测降水系统。  相似文献   
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