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101.
Knapped stone tools constitute an interesting evidence of the mental abilities of their makers. Almost imperishable, they bear visible traces of the successive removals they come from, and of the flaking techniques used. On that basis, we present a few remarkable achievements along the evolution of prehistoric lithic technology, and discuss their capabilities. The tools of the oldest Palaeolithic already surpass the nut cracking from Chimpanzees. Some core reductions into flakes, as early as 2.3 My, show a repeated organization of the removals, and the capacity to prevent a problem. The regular and symmetrical hand-axes from Africa and Europe, appearing between 1 and 0.5 My, provide evidence of a mental template and hence a capacity of conceptualization. The Levalloisian core reduction, somewhat more recent, give evidence of a goal structured method: the technical actions were hierarchized and subordinate to morphological intentions. 相似文献
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本文主要介绍了陶寺遗址石制品复制实验的目的、方法、过程和结果,其中,过程部分主要介绍了磨制石器的复制。结果部分主要是通过实验考察了陶寺遗址磨制石器生产所需的几种工艺,以及这些工艺的操作所需的工具、时间等因素。文章认为,陶寺遗址磨制石器的制作过程简单,一般只需打片和磨两个步骤。磨比较简单易操作,只是比较耗费时间;而打片相对于打制石器来讲,要简单很多。因此,陶寺遗址磨制石器的制作工艺总体来讲比较简单易操作。 相似文献
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J. F. Parr 《Economic botany》2002,56(3):260-270
For Australian Aboriginal people plant resins have played an important role in both trade and the manufacture of hafted tools.
In particular, the resins of theXanthorrhoea species were widely distributed and favored resources. The aim of this pilot study was to: (1) determine if starch grains
were present in all of theXanthorrhoea resin samples examined, and (2) determine the feasibility of discriminating between resins of differentXanthorrhoea species by the morphological attributes of their starch grains. The results established that starch grains were present within
all of theXanthorrhoea species resins that were examined. Moreover, for the purpose of identifying resins from within this genus the preliminary
results suggest that starch grains have sufficient differences in attributes to allow discrimination between species. The
results suggest that further research into the morphological attributes of starch grains in resins may prove to be an efficient
and cost-effective means by which species identification could be achieved for small portions of archaeological resin samples.
Resumen Las resinas de las plantas han tenido un papel muy importante para los Aborigenes Australianos en el intercambio y en la manofactura de herramientas con mangos. En particular, las resinas de las especiesXanthorrhoea eran recursos ampliamente distribuidos y preferidos. El objetivo de este estudio piloto fue: I) establecer si los granos de almidon estaban presentes en todas las muestras estudiadas de resina deXanthorrhoea y2) determinar la factibilidad de discriminacion entre las resinas de diferentes especies mediante los atributos morfológicos de sus granos de almidón. Los resultados establecieron que los granos de almidón se encontraban presentes en todas las especies de resinaXanthorrhoea examinadas. Ademas, para este proposito de identificar resinas desde dentro del genero glos resultados preliminares sugieren que los granos de almidón tienen suficientes diferencias en atributos para permitir la discriminación entre las especies. Los resultados indican que futuras investitigaciones dirigidas a las caracteristticas morfológicas de los granos de almidón en las resinas pueden ser un medio eficiente y barato a trovés del cual se puede lograr la indentificacion de especies.相似文献
105.
Specific Features of Development of Megagametophytes and Embryos of the Siberian Stone Pine in vitro
Seedlings were grown in vitro from fertilized eggs and immature embryos of the Siberian stone pine. Cultivation of megagametophytes on a hormone-containing Murashige-Skoog medium from the egg formation until the globular embryo stage made it possible to manipulate fertilization and embryogenesis. Immature embryos are the most promising for in vitrocultivation. Their maturation and germination proceed within seven days of cultivation. When zygotic embryos were cultivated, adventitious buds were formed from cells at the cotyledon base and tips. When adventitious buds were subcultivated on a medium containing benzylaminopurine and naphthylacetic acid, organogenic callus and shoots were formed. Thus, cultivation of megagametophytes and embryos of the Siberian stone pine led to the completion of embryogenesis and formation of viable of seedlings. 相似文献
106.
Nested PCR Assays for Detection of Monilinia fructicola in Stone Fruit Orchards and Botryosphaeria dothidea from Pistachios in California 总被引:4,自引:0,他引:4
Nested polymerase chain reaction (PCR) assays were developed based on microsatellite regions for detection of Monilinia fructicola, the causal agent of brown rot of stone fruits, and Botryosphaeria dothidea, the causal agent of panicle and shoot blight of pistachio. The nested PCR primers specific to M. fructicola were developed based upon the sequence of a species‐specific DNA fragment amplified by microsatellite primer M13. The external and internal primer pairs EMfF + EMfR and IMfF + IMfR amplified a 571‐ and a 468‐bp fragment, respectively, from M. fructicola, but not from any other fungal species present in stone fruit orchards. The nested PCR primer pairs specific to B. dothidea were developed based upon the sequence of a species‐specific 1330‐bp DNA fragment amplified by microsatellite primer T3B. The external and internal primer pairs EBdF + EBdR and IBdF + IBdR amplified a 701‐ and a 627‐bp fragment, respectively, from B. dothidea, but not from any other fungal species associated with pistachio. The nested PCR assays were sensitive enough to detect the specific fragments in 1 fg of M. fructicola or B. dothidea DNA or in the DNA from only two conidia of M. fructicola or B. dothidea. The nested PCR assays could detect small numbers of M. fructicola conidia caught on spore‐trap tapes and detect visible infections of B. dothidea in pistachio tissues. Microsatellite regions with high numbers of copies are widely dispersed in eukaryotic genomes. The results of this study indicate that microsatellite regions could be useful in developing highly sensitive PCR detection systems for phytopathogenic fungi. 相似文献
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