全文获取类型
| 收费全文 | 141篇 |
| 免费 | 0篇 |
专业分类
| 141篇 |
出版年
| 2024年 | 1篇 |
| 2023年 | 1篇 |
| 2021年 | 3篇 |
| 2020年 | 3篇 |
| 2019年 | 3篇 |
| 2018年 | 3篇 |
| 2017年 | 9篇 |
| 2016年 | 10篇 |
| 2015年 | 2篇 |
| 2014年 | 3篇 |
| 2013年 | 26篇 |
| 2012年 | 9篇 |
| 2011年 | 6篇 |
| 2010年 | 11篇 |
| 2009年 | 9篇 |
| 2008年 | 10篇 |
| 2007年 | 4篇 |
| 2006年 | 6篇 |
| 2005年 | 4篇 |
| 2004年 | 2篇 |
| 2003年 | 3篇 |
| 2002年 | 3篇 |
| 2001年 | 1篇 |
| 2000年 | 1篇 |
| 1999年 | 1篇 |
| 1997年 | 1篇 |
| 1996年 | 1篇 |
| 1993年 | 2篇 |
| 1991年 | 1篇 |
| 1988年 | 2篇 |
排序方式： 共有141条查询结果，搜索用时 15 毫秒
31.
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
32.
This paper presents evidence for increased recovery of organic residues from archaeological pottery through use of a microwave‐assisted liquid chromatography protocol. C16:0 and C18:0 saturated fatty acids were obtained from archaeological potsherds recovered from nine Neolithic settlements in the Middle East dating between 4700 and 7300 cal bc , including materials that had not produced evidence for the survival of any lipid species through use of ‘conventional’ solvent extraction techniques. Compound‐specific isotopic analyses of C16:0 and C18:0 fatty acids in potsherd extracts subsequently revealed δ13C/δ12C compositions consistent with modern subcutaneous fats of wild boar and goats pastured on lands adjacent to the Jordan Valley, and residues from a modern pottery vessel used in the manufacturing of butter, cheese and yogurt in central Turkey. These results are presented as an illustration of capabilities of the microwave‐assisted recovery protocol. The reclamation of saturated and unsaturated fatty acids from archaeological pottery fragments recovered from a number of the earliest ceramic horizons in the Middle East is herewith reported, and the extraction methods and instrumental analytical techniques are described. 相似文献
33.
We have applied and refined methods for the determination of bulk hydrogen, carbon and oxygen isotope ratios in modern and archaeological resins. The modern resins have a wide range of isotopic values and vary within the same tree, between individual trees, with species and location. For all isotopes measured, there is a general trend of increasing depletion of the heavier isotope with increasing altitude. There is also a linear trend between depletion of δD and δ13C values with increasing latitude; this trend is less clear for oxygen, but is related to the meteoric water line. Two case studies using archaeological resins known or suspected to have been transported in antiquity have been investigated to determine whether isotopic signatures can assist in pinpointing the geographical origin of the resin: Pistacia sp. resin from Canaanite amphorae imported into Egypt from known geographical locations in the eastern Mediterranean during the Late Bronze Age, and Roman amphorae sherds lined with Pinus sp. resin from sites ranging from Britain to the eastern Mediterranean. These results show separate groupings between the two resin types (pine/pistacia) and between the modern/archaeological resins. Some archaeological samples are distinct from the others and the modern resins show differences between geographical areas. However, there are no clear patterns relating the different Canaanite fabrics or the suggested manufacturing site of the Roman amphorae. 相似文献
34.
ABSTRACT In this paper, we analyze the isotopic niche and resource use of the guanaco (Lama guanicoe), pampas deer (Ozotoceros bezoarticus) and marsh deer (Blastocerus dichotomus) on the temperate plain of the northern Pampa region in the southeast of South America. The measured stable isotope compositions in bone tissue are δ13C, δ15N and δ18O. All the analyzed samples were recovered from different archaeological sites from the late Holocene. According to the results, the guanaco was strictly confined to the Pampa plain environment, developing a broad niche based on C3 plants and a variable contribution of C4 grasses within a grazing trend. The pampas deer preferentially used the Pampa plain, but also the prairies on the borders of the wetland, showing eurioic characteristics and a narrower niche based on C3 plants. In turn, the marsh deer was strictly confined to wetland environments, developing a C3 diet–base, within a narrow isotopic niche and stenoic characteristics. The three mammals showed a wide range of intraspecific variability, which was a key factor in their adaptability to spatial and temporal changes in the vegetation coverage. In fact, the temporal trends of their isotopic values were concurrent with the major climatic variations of the Holocene. Differences in the correlations between the values of both carbon sources in both deer species compared with the guanaco suggest a distinct chemical composition of their diet and/or differences in the allocation of nutrients. The isotopic values of nitrogen and spacing of the carbon sources in guanaco (pseudoruminant) and both deer species (ruminants) show no significant differences between them, thus establishing the values for local large herbivores. Significant correlations between δ13C and δ15N were found in the guanaco and marsh deer. The regional and extra–regional variability in the guanaco's δ13Ccollagen and δ15N probably reflect the clinal variations in the vegetation coverage and the amount of rainfall. The collagen isotope values in the guanaco throughout the entire Holocene show that the humid Pampa would have shifted between being a more recurrent mesic and temperate plain with minor phases of dry–mesic conditions like during the Little Ice Age, and a humid and warm one at the peaks of the Holocene Thermal Maximum and the Medieval Climatic Anomaly. The guanaco and the pampas deer adapted to all the climatic changes that happened on the humid Pampa until the biological invasions of large European mammals changed the herbivores’ guild composition of this vast plain, pushing them into peripheral habitats due to competition. The within–species variability in isotopic signals through time and space make it necessary to carry out adequate sampling before reconstructing the diets of local past populations. 相似文献
35.
Tamer Koralay Mehmet Oruç Baykara Kıymet Deniz Yusuf Kağan Kadioğlu Bahadır Duman Chuan-Chou Shen 《Environmental Archaeology》2019,24(3):317-336
The coloured stones used in buildings and monuments were an indicator of power and wealth during the ancient times. In this study, Tripolis city samples have been compared with Tripolis quarry samples in order to recognise the provenance of the banded travertine blocks in the ancient city. The banded travertine samples have similar mineral compositions and mainly consist of calcite with minor amounts of dolomite, aragonite, clay and iron oxide minerals. These results are also supported by CRS studies. Calcite is in the form of needle-shaped crystals ranging between 0.163–1.418?mm (in city) and 0.303–1.270?mm (in quarry). Tripolis banded travertine samples show the similar compositional spread in terms of major oxide, trace elements. δ13CV-PDB values of banded travertines range from 1.93 to 5.25‰ (in city) and 2.99 to 3.99‰ (in quarry), δ18OV-PDB values change between (?16.93)–(?10.08) ‰ and (?15.93)–(?13.01)‰, respectively. The U–Th radiometric ages are determined between ～267 and 9?ka in Tripolis city samples and ～350 and 2?ka in Tripolis quarry samples. The minero-petrographic, geochemical, C–O and U–Th isotope results fairly matched with each other. It seems highly probable that the banded travertines in Tripolis city were extracted from the Tripolis quarry, which is located at the northeast of the antique city with a distance of 3?km. 相似文献
36.
Martin Rudwick 《Interdisciplinary science reviews : ISR》2016,41(2-3):268-277
Beginning with my recollection of hearing C. P. Snow's ‘Two Cultures’ lecture, I sketch my experience of building two academic careers in succession, first in one of the natural sciences and later in the history of such sciences. I outline both the difficulties and the rewards that I encountered in crossing the alleged gulf between the sciences and the humanities, but also emphasise the diversity of cultures that I experienced within each. I describe my own encounter with the academic culture of continental Europe, within which the concept of a monolithic singular ‘Science’ could be dismissed as an ‘anglophone heresy’, and viewed from which the Two Cultures debate could seem both provincial and redundant. 相似文献
37.
Frank A. J. L. James 《Interdisciplinary science reviews : ISR》2016,41(2-3):107-117
The notion of the existence of two opposed cultures, one literary and one scientific, has a long pedigree going back to nineteenth century. However, it was C.P. Snow's formulation of the idea in 1959 and F.R. Leavis's 1962 critique, which brought it to the fore in cultural discourse, where it has more or less remained ever since. The papers in this special double issue of Interdisciplinary Science Reviews examine the debate and its legacies from a variety of perspectives, while this introduction seeks to contextualise the issues raised and draw some contemporary lessons. 相似文献
38.
V. Tiesler A. Coppa P. Zabala A. Cucina 《International Journal of Osteoarchaeology》2016,26(2):191-202
This article explores the living conditions and specifically the possible etiologies of subperiosteal reactions among those seafarers who did not survive Christopher Columbus' second voyage to the Americas and died at La Isabela, the first permanent European settlement in the New World, which is located in the present‐day Dominican Republic. The town was founded in 1494 by Christopher Columbus (1451–1506) and occupied for only 4 years. This study analyses the macroscopic and histological evidence of the skeletal series excavated from this contact cemetery, which is presently curated at the Museo del Hombre Dominicano. Twenty of the 27 systematically scored individuals reveal subperiosteal bone accretions, and in at least 15 individuals, these accretions appear bilaterally. The morphology, distribution and healing stages of the majority of these lesions provide new, direct evidence suggesting severe adult scurvy, a condition caused by sustained vitamin C deprivation, which was common among seafarers before the 18th century. The historical context surrounding the individuals' death at the European contact settlement and the conditions and duration of Christopher Columbus' second transatlantic voyage to the New World represent key elements in the interpretation of these lesions. In this case, the evidence also corroborates the known failure of Columbus' crew to exploit the locally available foods rich in vitamin C. Scurvy probably contributed significantly to the outbreak of sickness and collective death within the first months of La Isabela's settlement, an aspect that inflects the current discussion about the degree of virulence of New World infections that decimated the European newcomers, who we conclude to have been already debilitated and exhausted by scurvy and general malnutrition. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
39.
X‐L. Chen Y‐M. Fang Y‐W. Hu Y‐F. Hou P. Lü J. Yuan G‐D. Song B. T. Fuller M. P. Richards 《International Journal of Osteoarchaeology》2016,26(5):808-817
During the late Longshan period (ca. 4200–3900 BP) settlements on the Central Plains of China underwent a diversification in food production technologies, which set the stage for rapid economic and social development. The introduction of novel domesticates such as rice, wheat, cattle, and sheep not only provided more food choices, but also changed ideas concerning land use, farming techniques, and the use and mobilization of large scale labor forces. To better understand the contribution that these new dietary items and practices made to shaping the late Longshan period societies, a stable isotope ratio study of humans (n = 12) and animals (n = 42) was conducted at the late Longshan period site of Wadian. The human δ13C and δ15N values are clustered into two distinct groups. One group of nine individuals (δ13C = −9.9 ± 0.7‰; δ15N = 7.5 ± 0.5‰) had a predominately C4 diet based on millet grains with little protein input from the domestic animals. The other group of three individuals (δ13C = −14.3 ± 0.8‰; δ15N = 10.2 ± 0.3‰) had a mixed C3/C4 diet of millets and rice and were consuming sheep and cattle. The animals also displayed dietary diversity with the pigs (δ13C = −11.3 ± 2.5‰; δ15N = 6.9 ± 1.0‰, n = 10) and dogs (δ13C = −10.1 ± 1.0‰; δ15N = 7.2 ± 1.1‰, n = 7) having mostly a C4 plant based diet (millets). In contrast, the cattle (δ13C = −12.8 ± 2.1‰; δ15N = 7.6 ± 0.7‰, n = 9), sheep (δ13C = −16.7 ± 0.9‰; δ15N = 7.6 ± 0.1‰, n = 2), and cervids (δ13C = −20.8 ± 0.9‰; δ15N = 5.0 ± 1.2‰, n = 10) had diets with a greater contribution from C3 sources such as rice and wild plants. The discovery that humans and animals had different subsistence patterns indicates dietary complexity at Wadian and that rice agriculture, and cattle and sheep husbandry practices were already an important part of the local economy by the late Longshan period in the southern region of the Central Plains of China. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
40.
《International Journal of Osteoarchaeology》2018,28(2):131-142
The application of biomolecular techniques for the study of food practices in the Italian Bronze Age has revealed an interesting complexity. This is particularly true for the Po plain, in northern Italy, where the use of “alternative” grains (i.e., the millets) has been assessed isotopically through the measurement of stable carbon (δ13C) and nitrogen (δ15N) isotope ratios in human and animal bone collagen at the site of Olmo di Nogara (Verona). This work provides new isotopic data from 12 Early, Middle, and Late Bronze Age sites from western Veneto and Friuli. Data obtained contribute to the understanding of mode and tempo of the spread of new crops in northeastern Italy, which appears to be a hotspot for the study of Bronze Age farming economies in Europe. We have successfully analyzed 146 specimens to find that δ13C values are higher, in a way that we interpret as indicative of C4 plant consumption. Four of the sites analyzed, with a specific chronological indication, show this evidence. We explain this phenomenon as the result of a discontinuous spread of new crops in northeastern Italy at a very specific moment of the Bronze Age. The data presented might call for a reconsideration of food production and consumption among Bronze Age groups of southern Europe. 相似文献