首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   167篇
  免费   10篇
  2023年   3篇
  2022年   4篇
  2020年   2篇
  2019年   6篇
  2018年   6篇
  2017年   3篇
  2016年   4篇
  2015年   8篇
  2014年   3篇
  2013年   31篇
  2012年   15篇
  2011年   15篇
  2010年   17篇
  2009年   13篇
  2008年   16篇
  2007年   7篇
  2006年   5篇
  2005年   2篇
  2004年   2篇
  2003年   3篇
  2002年   2篇
  2000年   1篇
  1999年   1篇
  1997年   1篇
  1993年   1篇
  1985年   1篇
  1983年   2篇
  1982年   1篇
  1981年   1篇
  1978年   1篇
排序方式: 共有177条查询结果,搜索用时 500 毫秒
41.
The technology of the European Upper Palaeolithic yielded abundant evidence of the use of composite projectile heads, in the form of osseous points on the side of which one or several (micro)lithic elements are attached. Yet, little experimental work has been devoted to testing and assessing the parameters of use of this type of composite tips. In this paper we present a pilot experiment with replicas of Magdalenian composite spear tips, made of an antler point with one or two rows of flint backed bladelets. Two series of replicas were manufactured after the lithic and osseous record of, respectively, the Lower Magdalenian from southwest France (c. 20–18 Ky cal BP) and the Upper Magdalenian of Pincevent in the Paris Basin (c. 15–14 Ky cal BP). The 34 experimental composite heads were hafted to spears that were then shot with a spearthrower at the carcasses of two young deer. The results provide some insight into the performance characteristics of the osseous and lithic components, both in efficiency and durability. Finally, possible improvements of the experimental protocol are discussed, as well as the implications of our results for the understanding of projectile point variability in the Upper Palaeolithic.  相似文献   
42.
Lithic raw material constraints are widely assumed to be a determining factor of flaked stone tool morphology, but this assumption remains largely untested. We conducted a controlled experiment to determine whether a knapper’s growing replication skills would be hindered if the toolstone used was switched from large flakes of an easily worked chert to nodules of less tractable one. Two batches of Preferential Levallois cores were knapped, an earlier series made from standardised large flakes of sediments dominated by chalcedonic quartz followed by a more challenging one using variably-shaped, cortical nodules of microcrystaline quartz that varies in the completeness of quartz replacement of calcite and dolomite. Skill level markers were designed to measure the knapper’s ability to achieve a series of set goals. These were quantified and subjected to statistical testing. In all but one test, significant increases in skill could be detected from the earlier to the later batch of reductions, despite the drop in toolstone quality. Significant improvements in the consistency of the knapper’s output could also be detected. However, the switch to a more challenging, nodular chert did require extra shaping, which resulted in more waste. This masked visible progress towards producing a less costly core. Overall, our results do not support the assumed primacy of toolstone constraints over other factors in influencing the morphology of flaked stone tools.  相似文献   
43.
曾宇  刘芳 《四川文物》2020,(2):114-118
2019年11月,"中国西南与东南亚冶金技术的起源与传播暨临邛冶铁实验考古"国际学术研讨会在四川邛崃市召开。来自海内外的百余位学者,就中国西北与西南、中亚、东南亚地区冶金技术的起源与传播进行深入探讨,并在临邛汉代冶铁实验考古现场就汉代冶铁和炒钢的技术与工艺、考古遗迹与各个生产环节的对应关系、出土冶铸遗物的科技检测分析等问题展开讨论。与会代表一致认为,研讨会的召开不仅展示了亚洲大陆冶金考古的新发现和新成果,临邛冶铁实验考古也为今后冶金考古研究提供了新的思路和有效借鉴。  相似文献   
44.
1959年5月,为适应防疫的需要并迎接新中国成立10周年,中华人民共和国卫生部、中国人民解放军总后勤部卫生部和中华医学会在北京联合召开了全国急性传染病学术会议。会议贯彻中西医结合的卫生工作方针,结合时代发展需要,交流并总结了新中国成立以来医学界在防治急性传染病方面取得的成功经验,制定了8种急性传染病防治方案,对此后的传染病防治和研究起到了重要的推动作用。此次会议既为当代中国防疫史增添了浓墨重彩的一笔,同时也在我国医学发展史上具有重要意义。  相似文献   
45.
The possibility of determining the human or animal origin of bones from the lattice parameters of their inorganic bioapatite phase, when subjected to a high temperature treatment using the powder X-ray diffraction (XRD) technique, has been explored on a wide number of specimens. Forty-two animal bones were treated in a furnace at 1100 °C for 36 min and compared to 53 cremated human bones from a range of ancient necropolises. The X-ray diffraction patterns of bioapatite were simulated using both monoclinic P21/b and hexagonal P63/m structures to verify any occurrence of phase transformation and any difference in the lattice parameters due to the model. It was determined that the differences between the a-axis and c-axis of the monoclinic and hexagonal lattice were unimportant. Some outlying values were revealed to be caused by the presence of chlorine ions diffused into the apatite structure increasing its average unit cell values. Nevertheless, our results clearly show that in terms of lattice parameters the variability of human specimens are completely overlapped by the non-human variability making the use of XRD in order to distinguish animal from human bones questionable.  相似文献   
46.
The “North Atlantic Ice-Edge Corridor” hypothesis proposes that sometime during the Last Glacial Maximum, roughly 26,500–19,000 years ago, human populations from southern France and the Iberian Peninsula made their way across the North Atlantic and colonized North America. A key element of that hypothesis is the apparent similarity between stone-tool-production techniques of Solutrean peoples of Western Europe and Clovis and purportedly pre-Clovis peoples of eastern North America, most especially the supposed intentional use of “controlled overshot flaking,” a technique for thinning a bifacial stone tool during manufacture. Overshot flakes, struck from prepared edges of the tool, travel across the face and remove part of the opposite margin. Experimental and archaeological data demonstrate, however, that the most parsimonious explanation for the production of overshot flakes is that they are accidental products created incidentally and inconsistently as knappers attempt to thin bifaces. Thus, instead of representing historical divergence, overshot flakes in Clovis and Solutrean assemblages mark convergence in the use of the same simple solution for thinning bifaces that produced analogous detritus.  相似文献   
47.
This paper incorporates an experimental approach to the study of violence patterns in Northeastern Patagonia (Argentina) during the late Holocene. The underlying hypothesis considers a close association between socio-ecologic alterations during the Medieval Climatic Anomaly (MCA) (ca. 1150-600 years BP; Stine, 1994, 2000) and a probable increase in conflict levels. In order to test this hypothesis, human skulls (n = 986) were analyzed for bone lesions, discriminating late bone lesions, such as those produced by metal tools. The experimental approach used swine (Sus scrofa domestica) skulls, as proxies for human skulls, and incorporated original sabers. From this discriminating analysis, it can be inferred that no significant increase in violence signs were recorded until the first stages of Hispanic-indigenous contact (first half of 17th century). These findings emphasize the need for a revision of the implications of the dynamics of human populations in Northeastern Patagonia during the late Holocene.  相似文献   
48.
Substantial damage sustained during several recent earthquakes was non structural in nature. The economic consequence in terms of non structural component damage far exceeded the structural damage. Currently, there are several analytical studies that address the interaction between non structural components or Secondary systems (S-systems) and the main supporting structure or Primary system (P-system). Only a few of these analytical approaches have been proposed to evaluate and characterize the response of the S-systems attached to torsionally coupled P-systems. In addition, the experimental verification for the analytical approaches is scarce.

In the current study, the results and observations of an experimental research program conducted to characterize the behavior of both stiffness eccentric and mass eccentric torsionally coupled Primary-Secondary systems (PS-systems) are presented. From this experimental investigation it was found that the torsional yielding of the primary system has significant implications on the deamplification of near tuned secondary system response. The location of the S-system mounted on the P-system affects the peak response amplification, and interaction with the coupled P-system.  相似文献   
49.
The influence of masonry infills with openings on the seismic performance of reinforced concrete (R/C) frames that were designed in accordance with modern codes provisions is investigated. Two types of masonry infills were considered that had different compressive strength but almost identical shear strength. Infills were designed so that the lateral cracking load of the solid infill is less than the available column shear resistance. Seven 1/3 – scale, single–story, single–bay frame specimens were tested under cyclic horizontal loading up to a drift level of 40%. The parameters investigated are the opening shape and the infill compressive strength. The assessment of the behavior of the frames is presented in terms of failure modes, strength, stiffness, ductility, energy dissipation capacity, and degradation from cycling. The experimental results indicate that infills with openings can significantly improve the performance of RC frames. Further, as expected, specimens with strong infills exhibited better performance than those with weak infills. For the prediction of the lateral resistance of the studied single-bay, single-story infilled frames with openings, a special plastic analysis method has been employed.  相似文献   
50.
In this paper, the results of an experimental program dealing with the ultimate behavior of bolted beam-to-column connections under cyclic actions are presented. The design criteria adopted for tested specimens are discussed in detail, aiming to point out how the ultimate behavior can be governed by properly strengthening the components for which yielding has to be prevented. To this scope, the component approach is adopted as a design tool for component hierarchy criteria. The aim of the paper is the investigation of the actual possibility of extending the component approach to the prediction of the cyclic response of beam-to-column joints. To this scope, the attention has been focused on the possibility to evaluate the overall energy dissipation capacity starting from the energy dissipation of the single joint components, provided that they are properly identified and their cyclic behavior is properly measured.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号