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41.
李如意 《内蒙古师范大学学报(自然科学版)》2001,30(1):61-65
对扎兰屯市吊桥公园的鸟类进行了3年多的野外观察记录,共记录21科,6亚科,88种。其中非雀形目鸟类17种,占19.3%;雀形目鸟类71种,占80.7%。鸟类组成以夏候鸟和旅鸟为主。 相似文献
42.
LUO YunLi SUN XiangJun 《科学通报(英文版)》2007,52(15):2115-2122
Based on deep-sea pollen results (512-76 m) from ODP Site 1143 in the southern South China Sea (SCS),the climate and vegetation evolution sequence on the surrounding islands and the exposed continental shelf are discussed. The pollen records show that the pollen influx was quite low before 8.15 Ma and increased dramatically afterwards. The influx changes can be ascribed,on one side,to tectonics deformations around the southern SCS resulting in rapid uplift of islands and subsequent increase of the sediment rates and pollen influx and on the other side to climate cooling and monsoon enhancement. Around 2.63 Ma was another obvious boundary,the increasing of pollen and spores influx since this time was mainly related to global climate cooling. Spectrum analysis of pollen influx values shows that 2 Ma,0.67 Ma,and 0.19-0.17 Ma cycles existed during 12-3.0 Ma,while 0.1 Ma and 46.9 ka cycles existed during 3.0-2.0 Ma. 相似文献
43.
Monogenetic determinants of Alzheimer's disease: APP mutations 总被引:2,自引:0,他引:2
A. M. Goate 《Cellular and molecular life sciences : CMLS》1998,54(9):897-901
Mutations within exons 16 and 17 of the β-amyloid precursor protein (APP) gene were the first known cause of familial Alzheimer's disease. These mutations are rare
and have been reported in a handful of families exhibiting autosomal dominant inheritance of Alzheimer's disease with age
of onset around 50 years. In vitro and in vivo studies have demonstrated that each of these mutations alters proteolytic processing
of APP, resulting in an increase in the production of Aβ42, a highly fibrillogenic peptide, that spontaneously aggregates and deposits in the brain. Transgenic mice carrying a mutant
human APP gene also show age-dependent β-amyloid (Aβ) deposition in the brain. The rate of deposition in these mice can be modified by apolipoprotein E expression. 相似文献
44.
目的揭示中国典型季风区分子化石记录的生物分布的空间分异。方法利用GC-MS对典型季风区泥炭剖面进行分子化石的检测和分析。结果全新世时期,不同季风气候带的正构烷烃分布特征明显不同,从南到北依次为nC29—nC31(少量为nC25)—nC27,nC29,nC31为优势,说明不同地带同一时期植被输入呈明显的分异特征。结论中国全新世不同空间格局的生物,从南到北具有明显的空间分异特点,是生物-气候共同作用的结果。 相似文献
45.
利用遥感和地理信息系统提取2007—2008年夏季上海市蚊虫监测点缓冲区的土地利用状况和景观多样性数据,分析了区域水体、植被空间分布等区域景观特征及其变化对蚊虫密度消长的影响,为城市化过程中的蚊害防控提供参考依据.结果表明,本研究区内蚊虫密度与景观多样性、水网密度和植被密度成正相关关系,与景观破碎度成负相关关系,50%~70%植被覆盖度环境更有利于蚊虫繁殖,水域及水利设施用地的蚊虫密度高于其他用地类型.2007—2008年上海市夏季郊区的蚊虫密度高于市区,城市建设对蚊虫密度消长有重要影响. 相似文献
46.
近半个世纪以来中国季风区气温与降水变化及其时空差异 总被引:1,自引:0,他引:1
利用中国东部季风区20个测站1960-2012年气温和降水量的月值数据,采用线性趋势分析、Mann-Kendall突变检验、Morlet小波分析等方法,分析了季风区各区域年平均气温和年降水量的变化趋势、突变现象和周期特征.结果表明1960-2012年季风区各区域均有增温趋势,在20世纪90年代发生突变,东北地区发生突变要早于其他地区,北方地区的增温幅度大于南方,存在4年左右周期,8~16年的准周期,气温的高频变化周期在内陆地区表现更为明显;年降水量在53年里处于波动状态,四川盆地、华北地区和季风区西北部地区降水有减少趋势,长江流域下游降水有增加趋势,其他地区没有明显变化趋势,存在2~4年周期、8~16年左右准周期,降水的低频变化周期在近海地区表现更为明显. 相似文献
47.
青少年旅游与素质教育 总被引:2,自引:0,他引:2
旅游和素质教育密切相关.积极倡导青少年旅游活动,不仅是素质教育的客观要求,也是推动国民经济发展的重要举措. 相似文献
48.
《科学通报(英文版)》1999,44(Z1):20-20
This study generated a high-resolution paleoweathering record of the loess-soil sequence from the central Loess Plateau covering the last 220 ka using the ratio between the CBD (citrate-bicarbonate-dithionite) extractable free Fe_2O_3 (Fed) and total Fe_2O_3 (Fet). The new proxy shows a series of millennial oscillations, which are not necessarily documented by magnetic susceptibility from the same site. Because chemical weathering in the region depends mainly upon summer precipitation and temperature, we interpret these changes to be a result of millennial-scale variations in the strength of the East-Asian summer monsoon. Over the last glacial period, there is general agreement between the loess weathering record and the GRIP ice δ~(18)O record. The first suggests a rather stable summer monsoon pattern during the Last Interglacial period (marine δ~(18)O stage 5e). Large amplitude millennial oscillations of the summer monsoon seem to be particularly characteristic of the last glacial period whereas the fluctuations for the older periods are smoother. 相似文献
49.
合理的居住建筑通风设计不仅可以提高室内空气品质、满足人体的热舒适要求,而且可以降低建筑能耗。本文梳理了近年来我国夏热冬暖地区居住建筑通风设计的研究现状与标准规范,探讨了现有标准规范不全面、技术指标不统一、技术术语内容界定不明确、标准精细化不够、通风设计研究缺失、研究深度不够等方面存在的问题,并提出了相关建议,以期为设计研究与标准规范的完善提供参考。 相似文献
50.
LU Jun CHEN Muhong CHEN Zhong 《科学通报(英文版)》2006,51(B12):76-80
The relationship of species and abundance between the diatoms in the water and sediments from the southern South China Sea (SCS) were discussed, and the key environmental controlling factors were also investigated. Studies show that the diatom abundance is high in both water and sediments in the southeast part of the southern SCS and the varying trend is similar, while in the northwest part, the abundance is low, and the varying trend is different. The dominant diatom species are Thalassionema nitzschioides and Nitzschia bicapitata in water, and T. nitzschioides and Chaetoceros messanensis in sediments. The diatom species of small size and thin shell in water are more than in the sediments, while the diatom species of large size and thick shell in water are less. The percentage of species T. nitzschioides is higher in water of southeast part than in that of northwest part, but it is similar in sediments of both areas. It is shown that the southwest monsoon is the important factor influencing diatom abundance and T. nitzschioides percentage, and when the southwest monsoon is well developed, the distribution of diatom abundance and T. nitzschioides percentage are consistent in both water and sediments of the study area. 相似文献