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921.
中国西北地区汉,回,维,藏民族HLA—DRB基因多态性的研究   总被引:29,自引:2,他引:27  
赖淑苹  任惠民 《遗传学报》1999,26(5):447-457
按照第11届国际相容性抗原研讨会工作会议HLAⅡ类PCR-SSO分型标准和美国国立骨髓供者计划组织对HLA DRB位点等位基因分型要求,设计合成1对引物,扩增HLA DRB DNA片段,长度为256bp,设计合成不同片段大小探针27种,可检出DRB座位上DRB1的39种等位基因,DRB3的3种等位基因,DRB4的1种等位基因和DRB5的34种等位基因。  相似文献   
922.
青海省天峻地区藏原羚的食性分析   总被引:5,自引:0,他引:5  
2005 ~2006 年草青期和草枯期我们在青海省天峻地区随机收集了藏原羚的粪样,并利用粪便显微分析法对藏原羚的食性进行了研究。结果表明,藏原羚采食共计16 科34 属43 种植物,其中草青期采食16 科33 属42种,草枯期12 科22 属30 种。豆科植物是藏原羚采食的主要类群,禾本科、菊科、蔷薇科和莎草科其次,豆科、禾本科、菊科、蔷薇科和莎草科等五科植物占藏原羚采食总量的90% 左右。不同物候期,藏原羚的食性变化明显,豆科、蔷薇科在草枯期所占的比例显著低于草青期,而禾本科、菊科和莎草科所占比例则显著高于草青期。  相似文献   
923.
四川石渠县夏季藏原羚的分布和栖息地特征   总被引:5,自引:1,他引:4  
藏原羚 (Procaprapicticaudata)是青藏高原特有的有蹄类动物之一。在 2 0世纪 80年代以前 ,藏原羚的分布较广、数量较多 ,其游牧习性有利于草场植被的持续稳定 ,在青藏高原的草原生态系统中占据着十分重要的生态地位 (Schaller,1998;尹秉高和刘务林 ,1993)。然而 ,由于人类活动的增多直接导致其栖息地的退化 ,同时掠夺式的过度猎杀使这一重要物种的分布区正在不断缩小 ,数量也在急剧减少 (Schaller,1998;朴仁珠和刘务林 ,1993;刘永生 ,1988;毕俊怀和凤凌飞 ,1999) ,如在西藏 ,从 2 0世纪 80年代后期至 90年代中后期约十年的时间 ,藏原羚的…  相似文献   
924.
Our knowledge about soil organic matter (SOM) dynamics is limited although this is an important issue in the study of responses of ecosystems to global climate changes. Twelve sampling plots were set up every 200 m from 1 700 to 3 900 m along the vertical vegetation gradient along the east slope of Gongga Mountain. Samples were taken from all 12 plots for SOM content measurement, although only 5 of the 12 plots were subjected to radiocarbon measurements. A radiocarbon isotope method and a time-dependent model were used to quantify the SOM dynamics and SOM turnover rates along the vertical vegetation gradient. The results showed that the SOM turnover rate decreased and turnover time increased with soil depth for all vegetation types. The litter layer turnover rates presented a clear trend along the gradient. The litter layer turnover rates decreased with an increase in elevation, except that the litter layer turnover rate of mixed forest was higher than that of evergreen forest. Climatic factors, such as temperature and precipitation, were the main factors influencing the surface soil carbon dynamics. The turnover rates of the subsoil (including the A, B, and C horizons in the soil profiles) along the vertical gradient had no clear trends. The SOM of subalpine shrub and meadow turned over more slowly than that of the forest types in almost all soil horizons. The characteristic of short roots distributing in the upper part of the soil profile leads to different SOM dynamics of shrub and meadow compared with the forest types. Coniferous and mixed forests were susceptible to carbon loss from the young carbon pool, but their long and big roots resulted in high △^14C values of the deep soil profiles and increased the input of young carbon to the deep soil. In evergreen forest, the carbon cumulative ability from the B horizon to the C horizon was weak. The different vegetation types, together with their different modes of nutrient and carbon intake, may be the mechanism conditioning the subsoil organic matter dynamics.  相似文献   
925.
The Qinghai–Tibetan Plateau (QTP) has the highest elevations of all biodiversity hotspots. Difficulties involved in fieldwork at high elevations cause challenges in researching mechanisms facilitating species coexistence. Herein, we investigated Snow Partridge (Lerwa lerwa) and Tibetan Snowcock (Tetraogallus tibetanus), the only two endemic Galliformes on the QTP, to understand species coexistence patterns and determine how they live in sympatry for the first time. We assembled occurrence data, estimated habitat suitability differences and the underlying factors between two species at different scales using ecological niche models. Niche overlap tests were used to investigate whether niche differences between these species allow for their coexistence. We found that elevation was the most important factor determining habitat suitability for both species. At the meso‐scale, two species have similar ecological niches with their suitable habitats lying predominantly along ridge crests. However, ridge crests were more influential for habitat suitability by L. lerwa than for that of T. tibetanus because the latter species ranges further afield than ridge crests. Thus, differences in habitat suitability between these species lead to habitat partitioning, which allows stable coexistence. At the macro‐scale, temperature and precipitation were major factors influencing habitat suitability differences between these species. Tetraogallus tibetanus extended into the hinterland of the QTP and occurred at higher elevations, where colder and drier alpine conditions are commonplace. Conversely, L. lerwa occurred along the southeastern margin of the QTP with a lower snow line, an area prone to rainy and humid habitats. Niche overlap analysis showed that habitat suitability differences between these species are not driven by niche differentiation. We concluded that the coexistence of these two pheasants under high‐elevation conditions could be an adaption to different alpine conditions.  相似文献   
926.
本文分析了1986-1992年安徽黄山短尾猴鱼鳞坑群种群动态。结果表明,在研究期间该群以年平均10.3% 的速度增长,年平均产仔率66.9%。疾病导致个体死亡和雄猴的迁入与迁出对种群数量变化有一定影响。  相似文献   
927.
对白马藏族的皮纹学研究   总被引:3,自引:1,他引:2  
作者对四川省平武县的488例白马藏族健康人的皮纹进行了研究,其中男性246人,女性242人。将其皮纹参数与汉族、土族、彝族等民族的皮纹比较,经X~2及u检验处理,发现该民族的皮纹基本符合黄色人种的特点,但与汉、土、彝、藏诸族也存在若干统计学差异。认为若希冀皮纹学研究对该民族的识别有所帮助,需扩大样本,选择对照进一步研究。  相似文献   
928.
藏狐、虎鼬、艾鼬的核型分析   总被引:1,自引:1,他引:0  
本文报道了产于新疆的3种食肉目动物的染色体组型。藏狐(♀)2n=36,全部为双臂染色体。虎鼬(♂)2n=38,由33条双臂染色体,5条单臂染色体组成;在第1-3对染色体的长臂上恒定地出现次缢痕。艾鼬(♂)2n=38,由32条双臂染色体,6条单臂染色体组成。其染色体组型与等(1976)报道的艾鼬(♀)(新西伯利亚,诺俄尔比斯克)2n=38较为接近,而与王宗仁等(1984)报道的艾鼬(河北,怀来)2n=36,差异较大。  相似文献   
929.
Anthropogenic‐driven global change, including changes in atmospheric nitrogen (N) deposition and precipitation patterns, is dramatically altering N cycling in soil. How long‐term N deposition, precipitation changes, and their interaction influence nitrous oxide (N2O) emissions remains unknown, especially in the alpine steppes of the Qinghai–Tibetan Plateau (QTP). To fill this knowledge gap, a platform of N addition (10 g m−2 year−1) and altered precipitation (±50% precipitation) experiments was established in an alpine steppe of the QTP in 2013. Long‐term N addition significantly increased N2O emissions. However, neither long‐term alterations in precipitation nor the co‐occurrence of N addition and altered precipitation significantly affected N2O emissions. These unexpected findings indicate that N2O emissions are particularly susceptible to N deposition in the alpine steppes. Our results further indicated that both biotic and abiotic properties had significant effects on N2O emissions. N2O emissions occurred mainly due to nitrification, which was dominated by ammonia‐oxidizing bacteria, rather than ammonia‐oxidizing archaea. Furthermore, the alterations in belowground biomass and soil temperature induced by N addition modulated N2O emissions. Overall, this study provides pivotal insights to aid the prediction of future responses of N2O emissions to long‐term N deposition and precipitation changes in alpine ecosystems. The underlying microbial pathway and key predictors of N2O emissions identified in this study may also be used for future global‐scale model studies.  相似文献   
930.
AGO蛋白是RNA诱导沉默复合体的核心分子,在植物的生长、发育及胁迫响应中起重要作用.为探索青稞AGO基因在青稞抗条纹病病原菌过程中的作用机制,该研究以抗条纹病青稞品种‘昆仑14号’和感病品种‘Z1141’为材料,利用条纹病原菌侵染两品种,从感病前后的转录组测序结果中获得一个差异表达基因,克隆验证了该基因为HvtAGO...  相似文献   
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