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排序方式: 共有422条查询结果,搜索用时 15 毫秒
251.
  总被引:1,自引:0,他引:1  
To investigate whether there is neural dissociation between processing Chinese nouns and verbs, event-related potentials (ERPs) were recorded from 17 healthy undergraduate students while they read sentences silently. The results revealed that the late negative component (LNC) generated by nouns and verbs was significantly different. The strongest effect was in the 200—300 ms and 400—550 ms time window. In the first window, the negativity generated by verbs was more positive than that by nouns over the centro-frontal electrodes. In the second window, the negativity elicited by verbs was more positive than that by nouns over anterior areas and more negative than that by nouns over posterior areas. The results indicated the neural dissociation of processing Chinese nouns and verbs.  相似文献   
252.
National 2000’ GPS control network of China   总被引:3,自引:0,他引:3  
An accurately unified national GPS network with more than 2500 stations,named\"National 2000' GPS Control Net- work\",signed the epoch 2000.0,has been established by integrating the existing six nationwide GPS networks of China set up by differ- ent departments with different objectives.This paper presents the characteristics of the existing GPS networks,summarizes the strategies in the integrated adjustment of the GPS network,including functional model,stochastic model as well as the adjustment principle modifi- cation.By modifying the adjustment strategies according to the characteristics of the existing GPS networks and under the support of the IGS stations,the accuracy of the integrated national GPS network is greatly improved.The datum differences among the sub networks disappear,the systematic error influences are weakened,and the effects of the outliers on the estimated coordinates and their variances are controlled.It is shown that the average standard deviation for the horizontal component is smaller than 1.0 cm,the vertical component is smaller than 2.0 cm,and the three-dimensional (3-D) position of geocenter coordinates is smaller than 3.0 cm.The exterior checking ac- curacy for the 3-D position is averagely better than 1.0 cm.  相似文献   
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Phosphorus (P) deficiency in the soil is one of the major abiotic stresses that limit plant growth and crop productivity throughout the world. Development of cultivars with improved P-deficiency tolerance is an efficient strategy for sustainable agriculture. Plant roots play an important role in crop growth and development, especially in nutrient uptake and improvement of P-efficiency. Mapping quantitative trait loci (QTLs) for root traits and their response to low P stress at seedling stage will facilitate the development of P-efficient wheat cultivars. In this study, 30 QTLs (LOD>2.0) were mapped for the three root traits, such as root length, root number and root dry matter under different P supply conditions and their response to P-stress. These QTLs were distributed on 14 chromosomes, with each of the 5 QTLs explaining more than 10% phenotype variance. Analyses showed that root traits and their response to P-deficiency were controlled by different QTLs. In addition, alleles with positive effects were separated on both parents, and wheat cultivars with improved P-efficiency could be developed by accumulating these positive effect alleles together.  相似文献   
254.
    
The origins and phylogenetic patterns were assessed for G. przewalskii and G. eckloni by analyzing the complete mtDNA cytochrome b gene sequence (1140bp). Phylogenetic analyses further supported that there were three mtDNA lineages (A-C) identified in G. przewalskii and G. eckloni, demonstrating that outer rakers of the first gill have little significance in the phylogeny of the Gymnocypris fishes. The network established showed that G. eckloni of the Yellow River specific haplotype A1 was a founder and it radiated all haplotypes of G. przewalskii which suggested G. przewalskii might only originate from one of two maternals of G. eckloni from the Yellow River. Fs test and mismatch analysis showed at least two expansion events in the population of G. przewalskii about 0.2734 Ma and 0.0658 Ma, while G. eckloni from Qaidam Basin could have experienced severe bottleneck effect about 0.0693 Ma. The population expansion was detected in subclades A1 and A21 with the most recent common ancestor (TMRCA) about 0.2308±0.01 Ma and 0.1319±0.015 Ma, respectively, which were within the geological age range of “Gonghe Movement” event that caused the separation of Lake Qinghai from the upper Yellow River. These results suggested the effect of the fish diversification by rapid uplift of the Qinghai-Tibetan Plateau in the Late Pleistocene.  相似文献   
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Navy combat search and rescue(NCSAR) is an important component of the modern maritime warfare and the scenario of NCSAR is the basis for decision makers to rely on. According to the core elements in the NCSAR process, the NCSAR scenario structure is constructed from seven perspectives based on the multi-view architecture framework. According to the NCSAR scenarios evolution over time, the NCSAR scenario sequence is analyzed and modeled based on the concept lattice method. Then,the incremental co...  相似文献   
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