排序方式: 共有83条查询结果,搜索用时 10 毫秒
1.
模拟打制是史前考古研究中的重要实验考古方法之一,对于正确认识考古标本的类型和技术、解读当时人类的认知水平和知识积累具有不可取代的作用。本文简要回溯了模拟打制实验的发展史,并评述其应用现状。模拟打制实验在欧美有较长的发展与应用历史,但最终趋向了不同的发展方向。传统的模拟打制实验研究在欧洲得到了更加深入的继承和发展,而美国在上世纪90年代后期逐渐发展起了以定量控制、数理统计为核心的实验方法。本文以近期在山西丁村开展的角页岩模拟打制实验为例,介绍传统的模拟打制实验的基本流程和内容,包括实验的内容设计、实施及记录和分析等。本次实验结果肯定了硬锤锤击技术在丁村角页岩石核剥片和修理中的广泛应用,并在一定程度上否定了以往对使用碰砧法的推测。文章最后对模拟打制实验存在的问题和应用前景作了讨论和展望。 相似文献
2.
长期以来赭石利用行为被视为人类行为现代性的标志之一,受到国内外考古学界的普遍关注。本文回溯和梳理了全球背景下赭石利用的起源、发展及其与人类演化史的关系。在现代人广泛分布于全球之后,赭石利用行为更加丰富和多样化地出现在各地,然而现有考古证据表明该行为并不是解剖学意义上的现代人突变性的发明。赭石利用不能被单纯地定义为现代人行为,而应是有着长久演化积累的现代性行为之一。在长期传播与演化过程中,赭石的功能从意识形态、艺术表达等逐渐扩展到作为矿物成分被用于实际生产生活。赭石的利用历史可追溯到中更新世中期,但其广泛分布仍与晚更新世以来现代人的广泛扩散直接相关,对于理解现代人的意识形态、社会组织方式以及艺术表达、精神文化发展都具有重要的意义。国内目前所发表的相关考古学证据相对较少,以下马碑遗址为代表的材料,也恰处于现代人在全球广泛扩散的窗口期,并伴有进步的细小石器镶嵌使用的证据,成为认识东亚现代人行为的关键性考古证据。 相似文献
3.
长期以来,细石叶技术的发展和传播是更新世末期到全新世初期文化传播、人群迁徙和生态适应研究领域探讨的重要课题。20世纪50年代,发现于广东西樵山石器制造场的大批细石叶技术产品,突破了传统意义上对细石叶技术流行、传播范围的认识。早期研究中不少学者就西樵山细石叶制品的形态特征、分布情况进行了介绍,随后鲜见后续研究,缺乏对技术内涵、石核开发策略的深入解析,亦未开展对其所指示的文化传播与人口迁徙问题的探讨。本文选取收藏于中山大学人类学博物馆的343件细石叶石核,通过对石料、毛坯类型、台面类型和数量、剥片面等多方位观察以及对相关技术数值的测量统计,建构西樵山细石叶石核开发策略的模式。这项工作总结了西樵山细石叶技术的特点,并与其他区域的细石叶技术进行对比,加深了对出现在亚热带地区的细石叶技术的认识,为尝试进一步讨论其可能的技术源流和指示人口迁徙与文化传播提供了基础。 相似文献
4.
The availability of numerous universal markers and suitable phylogenetic analysis methods are both very important for phylogenomics inference. Based on PCR amplification, a total of 122 markers, which were amplified in 19 representative species, were developed for Laurasiatherian phylogenomics. Subsequently, we illustrated the utility of these newly developed markers using a subset of eight markers. We showed that both 'supermatrix' and 'supertree' trees generated similar topology, which accorded with the current understanding of the Laurasiatherian phylogeny in most aspects. Thus, markers developed here would be likely to make a contribution to resolving evolutionary relationships and inferring evolutionary histories of the Laurasiatherian mammals in the future. 相似文献
5.
Pal R Wang S Kalyanaraman VS Nair BC Whitney S Keen T Hocker L Hudacik L Rose N Cristillo A Mboudjeka I Shen S Wu-Chou TH Montefiori D Mascola J Lu S Markham P 《Journal of medical primatology》2005,34(5-6):226-236
Immunization of macaques with multivalent DNA encoding gp120 genes from HIV-1 subtypes A, B, C and E and a gag gene followed by boosting with homologous gp120 proteins elicited strong anti-gp120 antibodies capable of neutralizing homologous and to a lesser degree heterologous HIV-1 isolates. Both Env- and Gag-specific cell mediated immune (CMI) responses were detected in the immunized animals. Following rectal challenge with an SHIV isolate encoding HIV-1(Ba-L)env, plasma viremia in the infected immunized animals was significantly lower than that observed in the na?ve animals. Further, one of six immunized animals was completely protected whereas all six na?ve animals were infected. These results demonstrate that a vaccine based on priming with a polyvalent DNA vaccine from multiple HIV-1 subtypes followed by boosting with homologous Env proteins elicits anti-HIV-1 immune responses capable of controlling rectal transmission of SHIV(Ba-L). 相似文献
6.
细菌对胁迫应答因子RpoS的调控 总被引:1,自引:0,他引:1
RpoS是细菌一般胁迫反应的主要调控因子,可以诱导RpoS表达的胁迫条件包括碳源和氮源饥饿、渗透压升高、低pH、温度升高等。在细菌体内,大量环境和细胞内信号参与RpoS的调控。这些调控可以发生在转录和翻译水平、降解过程以及活性调节等方面,形成一个复杂的调控网络。RpoS调控机制的阐明对于了解胁迫条件下细菌响应机制具有重要意义。 相似文献
7.
Assessing the molecular control of development and cell fate in individual cells in the intact mammary epithelium has not been possible to date. By exploiting an intraductal retrovirus (RCAS)-mediated gene delivery method to introduce a marker gene, we found that ductal epithelial cells are turned over with a half time of approximately 1 month in adult virgin mice. However, following RCAS-mediated introduction of a constitutively activated STAT5a (caSTAT5a), caSTAT5a-activated ductal epithelial cells expand and replace other cells in the epithelium, eventually forming a mammary gland resembling that in a late pregnant mouse, suggesting that STAT5a activation alone is sufficient to mediate pregnancy-induced mammary cell expansion, alveolar cell fate commitment, and lactogenesis. Furthermore, such caSTAT5a-induced alveolar differentiation does not require ovarian functions, although caSTAT5a-induced cell proliferation is partly reduced in ovariectomized mice. In conclusion, in this first report of studying the developmental role of a gene in a few cells in a normally developed virgin mammary ductal tree, STAT5a activation causes alveolar fate commitment and lactogenesis, and with the help of ovarian hormones, drives alveolar expansion. 相似文献
8.
In the present study, sequence variations at four nuclear introns which were respectively from the parathyroid hormone-like (PTH) gene, isolate Pdalz1692 interferon (IFN) gene, peripherin-like (RDS) gene, and tyrosine kinase receptor-like (KIT) gene, were examined to analyze genetic diversity and population structure of the finless porpoise (Neophocaena phocaenoides) in Chinese waters. High among-population differentiation was revealed, with a significant genetic structure between populations (PTH: F(ST) = 0.29, P < 0.001; IFN1@: F(ST) = 0.23, P < 0.001; RDS: F(ST) = 0.12, P < 0.001; KIT: F(ST) = 0.16, P < 0.001) shown by the analysis of molecular variance. Although common haplotypes accounted for more than one half of all samples examined, many haplotypes were found to be population-specific. The Tajima's D, Fu's tests and mismatch distributions all suggested a recent colonization and population expansion of finless porpoises in Chinese waters. In view of special reference to the conservation priority of the Yangtze finless porpoises, special protection measures must be taken urgently for this population. 相似文献
9.
Shixia Xu Yuan Chen Yuefeng Cheng Dan Yang Xuming Zhou Junxiao Xu Kaiya Zhou Guang Yang 《Proceedings. Biological sciences / The Royal Society》2012,279(1746):4433-4440
The enlargement of cetacean brain size represents an enigmatic event in mammalian evolution, yet its genetic basis remains poorly explored. One candidate gene associated with brain size evolution is the abnormal spindle-like microcephaly associated (ASPM), as mutations in this gene cause severe reductions in the cortical size of humans. Here, we investigated the ASPM gene in representative cetacean lineages and previously published sequences from other mammals to test whether the expansion of the cetacean brain matched adaptive ASPM evolution patterns. Our analyses yielded significant evidence of positive selection on the ASPM gene during cetacean evolution, especially for the Odontoceti and Delphinoidea lineages. These molecular patterns were associated with two major events of relative brain size enlargement in odontocetes and delphinoids. It is of particular interest to find that positive selection was restricted to cetaceans and primates, two distant lineages both characterized by a massive expansion of brain size. This result is suggestive of convergent molecular evolution, although no site-specific convergence at the amino acid level was found. 相似文献
10.