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   1482篇
  免费   91篇
  2024年   9篇
  2023年   41篇
  2022年   16篇
  2021年   18篇
  2020年   63篇
  2019年   76篇
  2018年   89篇
  2017年   82篇
  2016年   73篇
  2015年   57篇
  2014年   58篇
  2013年   190篇
  2012年   118篇
  2011年   85篇
  2010年   82篇
  2009年   74篇
  2008年   81篇
  2007年   75篇
  2006年   60篇
  2005年   30篇
  2004年   18篇
  2003年   27篇
  2002年   20篇
  2001年   12篇
  2000年   17篇
  1999年   9篇
  1998年   6篇
  1997年   7篇
  1996年   7篇
  1995年   5篇
  1994年   4篇
  1993年   7篇
  1992年   3篇
  1991年   1篇
  1990年   1篇
  1988年   1篇
  1987年   1篇
  1985年   7篇
  1984年   6篇
  1983年   8篇
  1982年   7篇
  1981年   5篇
  1980年   5篇
  1979年   9篇
  1978年   3篇
排序方式: 共有1573条查询结果,搜索用时 947 毫秒
961.
Located in the historical center of Catania, Italy, in the Civita district, the Bonajuto Chapel is one of the oldest and best-conserved buildings of the city, which has survived the numerous earthquakes that struck eastern Sicily during the medieval and the modern ages, such as those particularly devastating in 1169 and 1693. However, both the date of this small monument, as well as its original use, still remain uncertain, as literary and documentary evidence are scarce and fragmentary. Most historians, analyzing prevalently the stylistic and constructive aspects, interpreted the chapel as a place of worship and assigned its construction to a rather long period of the early Middle Ages, from the 5th or 6th centuries ad to the 8th or 9th centuries ad—the phase during which the island was under the Byzantine domination. The excavations carried out in 1930 to 1939 and the last restoration works (in 2003) have not provided explicit chronological data. Its age determination is considered essential for a better knowledge of the real influence of this domination on the architecture of the Island. Therefore, a multidisciplinary and accurate analysis of the building using the existing bibliography has been carried out also in order to understand the functional and morphological transformations of the chapel during its long life. The thermoluminescence absolute dating methodology applied to some brickwork elements of the construction, has placed the monument chronology in a period of time that is notably shorter than that previously noted here. These new data, with the study of the architectural structure, have made a significant step forward in the knowledge of the chapel history.  相似文献   
962.
A simplified approach for analyzing the nonlinear response of masonry buildings, based on the equivalent frame modeling procedure and on the nonlinear equivalent static analyses, is presented. A nonlinear beam finite element (FE) is formulated in the framework of a force-based approach, where the stress fields are expanded along the beam local axis, and introduced in a global displacement-based FE code. In order to model the nonlinear constitutive response of the masonry material, the lumped hinge approach is adopted and both flexural and shear plastic hinges are located at the two end nodes of the beam. A classical elastic-plastic constitutive relationship describes the nonlinear response of the hinges, the evolution of the plastic variables being governed by the Kuhn-Tucker and consistency conditions. An efficient element state determination procedure is implemented, which condenses the local deformation residual into the global residual vector, thus avoiding the need to perform the inner loops for computing the element nonlinear response. The comparison with some relevant experimental and real full-scale masonry walls is presented, obtaining a very good agreement with the available results, both in terms of global pushover curves and damage distributions.  相似文献   
963.
In recent years, far-right organisations have formed in response to what they believe to be the threat from the rise of Islam in Australia. Parallel movements have spawned an extensive literature internationally. In this study I investigate this movement in Australia using automated text analysis of all public posts from two of the most popular Australian anti-Islam groups on social media. This approach complements traditional polling methods by offering access to large samples of the spontaneously generated opinions, allowing subjects to speak in their own words. My analysis finds evidence that concerns about terrorism and the perceived political threat from Islam are paramount in these groups’ discussion of Muslims. I conclude by discussing the implications for counter-messaging strategies.  相似文献   
964.
Numerous historical sources describe many aspects of the estate‐based society in medieval times; the detection of socioeconomic status within populations through skeletal remains is a topic of growing interest in anthropological studies. In medieval times, it was common for members of high social rank to be buried within or next to a church. This was certainly the case in Grevenmacher (Luxembourg), where remains of a church building and an adjacent cemetery from the 13th until the beginning of the 15th century were subjected to archaeological and anthropological analysis. By integrating archaeological and anthropological elements, as well as stable isotope analysis, we documented osteological manifestations as indicators of diet differentials in two subsamples (first group consists out of 56 individuals, second one out of 184 individuals) from the medieval cemetery of Grevenmacher. We could distinguish two subsamples that we assumed as different in their socioeconomic status with regards to the burials' position in the cemetery and burial characteristics. Differences in osteological traits such as bone length, stature and body mass indicated differences in diet between sample groups. To substantiate these outcomes, stable isotopic analysis (δ13C, δ15N) were made; the results displayed a clear separation between the sample groups on the basis of their diet. Therefore, we were able to confirm certain individuals in the medieval population of Grevenmacher in relationship to their socioeconomic status. Copyright © 2017 John Wiley & Sons, Ltd.  相似文献   
965.
ABSTRACT

Chemical residues preserved in floors can be considered anthropic activity markers. In fact, residues are strictly related to the activities performed and reflect their spatial distribution. We present a synthesis of the work carried out over the last few decades in Mexico and Italy related to the study of chemical residues in floors. Residues can be identified performing specific chemical analyses both of plastered or earthen floors samples. We outline a methodological approach concerning the use of the markers of the activities to interpret food production and consumption in the archaeological record, based upon evidence from experimental, ethnoarchaeological and archaeological examples. Here we point out the advantages and problems of such an approach, mainly related to equifinality, of the use of spot tests and gas chromatography coupled with mass spectrometry techniques using examples from different sites in the world.  相似文献   
966.
This paper presents the results of inter-disciplinary work drawing on archaeobotanical and archaeometric studies to trace the agroforestry landscape and the supply economy at the vicus of Thamusida in north-west Morocco at the border of the Roman Empire. The available data indicate the self-sufficiency of the settlement in both forestry and agricultural products throughout the period investigated from the end of the 1st century BC to the beginning of the 4th century AD. Charcoal data testify to the presence of a Quercus suber forest in the close surroundings of the site and its exploitation for a variety of forestry products such as timber, fuelwood, cork, and probably also leaves and acorns to feed livestock. The overwhelming presence of Q. suber in the archaeological layer investigated clearly indicates that this forest was under human influence prior to Roman occupation and was already partially degraded. Charred seed and fruit remains suggest that the diet of both troops and civilians was mainly based on locally grown products and that all the inhabitants of the site had access to good cereals such as barley, naked wheats and pulses with large seeds such as horse bean and pea; quality fruits, such as olive and grape, were also produced locally for fresh consumption. Organic residue analyses of the contents of ceramic vessels and plastered vats allowed archaeobotanical data to be complemented, thereby shedding light on some of the imports at Thamusida. Despite the remote location of this settlement, imported goods such as oil and wine were transported here in amphorae from different parts of the Empire.  相似文献   
967.
ABSTRACT

Despite the high vulnerability of historic structures to earthquakes, the approaches for evaluating seismic demand and capacity still appear inadequate and there is little consensus on the most appropriate assessment methods to use. To develop an improved knowledge on the seismic behavior of masonry structures and the reliability of analysis tools, two real-scale specimens were tested on a shake table, and several experts were invited to foresee failure mechanism and seismic capacity within a blind prediction test. Once unveiled, experimental results were simulated using multi-block dynamics, finite elements, or discrete elements. This article gathers the lessons learned and identifies issues requiring further attention. A combination of engineering judgment and numerical models may help to identify the collapse mechanism, which is as essential as it is challenging for the seismic assessment. To this purpose, discrete modeling approaches may lead to more reliable results than continuous ones. Even when the correct mechanism is identified, estimating the seismic capacity remains difficult, due to the complexity and randomness of the seismic response, and to the sensitivity of numerical tools to input variables. Simplified approaches based on rigid body dynamics, despite the considerable experience and engineering judgment required, provide as good results as do advanced simulations.  相似文献   
968.
School gardens are widely celebrated as spaces to promote health and sustainability by connecting children with their food. While scholars have assessed the effects of gardening in practice, media discourses play a key role in constituting this site. This paper examines how the school garden is discursively constituted within American and Canadian newspaper coverage. The analysis reveals specific forms of connection that are said to flourish in the school garden: between food production and consumption, between bodies and knowledge, and between the urban child and nature. While all children are said to benefit from connecting with their food, these connections are articulated differently in relation to particular bodies and spaces, evident in racialized and classed narratives of stewardship and salvation. As children’s relationship to food is invested with the hopes and fears of collective futures, the discursive construction of the school garden provides crucial insights into contemporary understandings of childhood.  相似文献   
969.
Mexican prehistory is characterized by migration and population isolation in its earliest phase, followed by later inter‐population cultural interactions, such as politics and trade. While shared, common morphological variants are often informative about recent population events, rare trait variants have not been widely investigated to see whether they might be informative about earlier events. Here, we consider populations that show several rare variants at frequencies high enough to warrant such an investigation. Examining past population structure can help us understand population interactions across different periods of time, levels of migration, and population isolation/drift. Multiple‐origin populations may have more variation, including more and higher rates of rare traits. We examined maxillary lateral incisors in 1117 dentitions from 76 samples of Preclassic/Classic and Postclassic pre‐European contact Mexico and the American Southwest for the prevalence of rare lateral incisor variants. Variants observed included barrel, congenital absence, interruption groove, mesial marginal bending, peg, reduced, supernumerary, and talon teeth. The most common variant overall is interruption groove. Central Mexico, Huasteca, and the Lowland Yucatan region samples present the highest overall number of incisor variants. Higher frequencies of single unusual traits are commonly found in samples from smaller populations, while samples from larger population centres show a greater range of these rare variants. We investigated to see whether the pattern of rare incisor variant frequencies reflected early or later population history by comparing similarity/distance matrices and factor model matrices using Mantel tests and Generalized Procrustes analysis. Results show a weak relationship with the Postclassic period and shared migration/language and trade interaction models. We suggest that later cultural interactions have acted to mask earlier population history. Research on serial founder effects should be approached multiregionally and across time, to avoid missing inter‐region biological relationships. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   
970.
邻里作为城市居民的重要日常生活场所,对健康的影响引起广泛关注。本文选取武汉市南湖街道这一典型住区,运用多元回归分析,针对商品房和保障房邻里展开对比研究,解析不同类型邻里中居民的邻里环境感知对自评健康的影响差异。研究发现,控制个人因素后,体育休闲设施感知、归属感和安全感显示出对自评健康独立且显著的影响。而在对比研究中,商品房邻里的居民自评健康受邻里环境感知的影响较显著,而保障房邻里的居民自评健康受个体层面特征的影响较显著。因此,宜针对不同类型邻里制定差异化的社区健康提升策略。  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