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   694篇
  免费   32篇
  2023年   10篇
  2022年   6篇
  2021年   7篇
  2020年   24篇
  2019年   29篇
  2018年   32篇
  2017年   26篇
  2016年   40篇
  2015年   11篇
  2014年   30篇
  2013年   99篇
  2012年   33篇
  2011年   26篇
  2010年   29篇
  2009年   29篇
  2008年   38篇
  2007年   35篇
  2006年   44篇
  2005年   32篇
  2004年   28篇
  2003年   24篇
  2002年   19篇
  2001年   19篇
  2000年   16篇
  1999年   13篇
  1998年   11篇
  1997年   5篇
  1996年   3篇
  1995年   2篇
  1994年   1篇
  1993年   1篇
  1992年   1篇
  1991年   1篇
  1989年   2篇
排序方式: 共有726条查询结果,搜索用时 15 毫秒
91.
92.
Fourteen Bivalvia species are described from the Lower Permian Río Genoa Formation, exposed in the southern Tepuel-Genoa Basin (Chubut Province, Argentina), of which one, Fletcheripecten genoensis, is new. The studied specimens are well preserved, retaining fine details of the ornament and shell morphology. Palaeotaxodonta is represented by two species of Nuculopsis and four species of Phestia; Pteriomorphia by five species in five genera; and Heteroconchia by three informal species. Most of the species recorded also occur in the northern part of Tepuel-Genoa Basin and allow demarcation of new and distinct marine intervals in the Río Genoa Formation, which was classically interpreted to represent continental deposits. The bivalve fauna confirms a Cisuralian (Early Permian) age for the Río Genoa Formation and offers potential for improved regional and global correlations.  相似文献   
93.
A 13th‐century‐BC shipwreck site, Hishuley Carmel, is described and discussed. It provides direct evidence for marine transport of copper and tin along the Israeli coast and may indicate inland and maritime trade‐routes of metals in the Mediterranean. The shipwreck represents a supply‐system providing the demand for bronze in the Levant. Trace‐elements and lead‐isotope analysis suggest that the copper came from Cyprus, similarly to bun and oxhide ingots from Uluburun. The source of the tin cannot yet be ascertained. The medium‐size ship was probably grounded and wrecked during a storm. Some of the cargo may have been salvaged in Antiquity. © 2012 The Authors  相似文献   
94.
The wrecking of the Falmouth Postal Packet Hanover in 1763 led to three legal disputes and two court cases—in 1766 and 1997. This article recounts the origins and course of these disputes. It examines what the resolution of the 18th‐century case and the second dispute has revealed of the law and practice of marine insurance in the mid 18th century. It further examines what the 20th‐century case has revealed concerning the tension between ancient principles of commercial salvage and modern principles of heritage protection. Somewhat fortuitously, the examination of the case provides an opportunity to advance a simple solution to this conflict.  相似文献   
95.
Occlusal surface wear scores were examined in a sample of 200 Formative period (1500 bc–ad 500) skeletons from the lower Azapa Valley in northwest Chile. Wear rate and plane (angle) were additionally evaluated using a subsample of paired first and second mandibular molars. The Formative period represents the transition from marine foraging to agro‐pastoral dependence in the region, and differences in oral pathology indicate that diet varied by site location (coast vs valley interior) but not by archaeological phase (early vs late). We predicted that occlusal wear would demonstrate similar patterns, resulting from differences in food consistency, and therefore hypothesised that in coastal groups consuming greater quantities of foraged foods, occlusal surfaces should wear faster and exhibit flat molar wear, whereas among valley interior groups consuming greater quantities of agro‐pastoral products, these should wear slower but exhibit more angled molar wear. Heavier posterior tooth wear was identified among coastal residents, but rate and angle of molar occlusal attrition did not differ significantly by location. Heavier overall wear and a steeper molar wear plane were identified during the early phase indicating that food consistency varied somewhat over the course of the Formative period. Overall, the results indicate that, although limited differences in tooth wear exist by site location, wear varied more over time likely reflecting a gradual transition from foraging to agro‐pastoral dependence in the lower Azapa Valley. Although oral health indicators point to differences in dietary investment by location, maintenance of a mixed subsistence economy likely sustained a comparative consistency of foodstuffs. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   
96.
Marine archaeological remains in the Raja Ampat waters play an important role in the development of maritime history and culture in Indonesia. Three World War II American P47-Razorback planes are preserved here and the site has been developed for tourists and a research laboratory for scientists. However, the site is tectonically active which threatens the wrecks.  相似文献   
97.
Abstract

Over the past few decades, the archaeological community has been moving away from the more traditional methods of excavation and recovery of underwater cultural heritage towards a less intrusive management approach, essentially involving the preservation of sites in situ. This trend has been politically galvanized in Article 2, point 5 of the Convention on the Protection of the Underwater Cultural Heritage (), which states that ‘The preservation in-situ of underwater cultural heritage shall be considered as the ?rst option before allowing or engaging in any activities directed at this heritage’. Over the years, a number of different remediation strategies have been utilized in order to protect underwater cultural heritage sites in situ, and most of the techniques or combinations thereof involve reburial of sites. Reburial may be an appropriate means of stabilizing and decreasing the deterioration rate of a site, however, there needs to be a holistic approach to the study of the environment, before and after reburial, to gain a full understanding of the changes that are occurring on the site and determine the effectiveness of the technique.

In early 2000, the James Matthews, a copper-sheathed, wooden-hulled vessel wrecked in 1841 south of Fremantle, Western Australia, was identi?ed as being under considerable threat from increased site exposure due to a combination of natural near-shore sedimentary processes and industrial activity in the immediate area. An extensive on-site conservation survey was carried out to establish the state of preservation of the wreck and provide information regarding the physico-chemical and biological nature of the environment prior to the implementation of any mitigation strategy. In 2003 it was con?rmed that further exposure of the site was occurring and devising a management plan was of paramount importance.

Since this time a number of different reburial techniques have been trialled on the site and these include sand bags of differing material composition, polymeric shade cloth, arti?cial sea grass mats made from polyvinyl chloride bunting, and the use of interlocking medium density polyethylene ‘crash barrier’ units in a cofferdam arrangement to con?ne deposited sand. The geological, physico-chemical, and microbiological changes in the burial environments have been monitored over this time. Furthermore, the broader scale, near-shore sedimentary processes affecting the site are being assessed in order to establish the reasons behind the continuing sediment loss. In situ preservation of the iron ?ttings by cathodic protection has also been included in these ?eld trials. In this paper the results from these experiments will be summarized. This information will be used to ?nalize the design of the full-scale in situ preservation strategy for the site and assist in establishing a post-reburial monitoring programme that will measure the success of the adopted remediation technique.  相似文献   
98.
Abstract

This paper explores the case of the Khami archaeological site, whose degradation by the local communities in recent years was as a result of socio-economic problems caused by the collapse of the Zimbabwean economy combined with the inability of the Zimbabwean government to support the site. We argue that the negative attitude by the local communities towards the management of cultural heritage sites is embedded in the colonial history of the country, and has been driven by the socio-economic difficulties emanating from the collapse of the Zimbabwean economy in recent years. We begin by explaining the history of Khami, its architecture, and the local communities residing around it. We then show and assert that the subsequent degradation of Khami and the landscape around it by the local communities is linked to the socio-economic problems of the country and poverty, which emanated from the collapse of the Zimbabwean economy. In the end, we contend that the economic constraints are part of the reasons why the local communities have from time to time failed to respect the importance of protecting cultural heritage sites in the country.  相似文献   
99.
This article examines the impact of détente on the Italian political system, linking together internal and international dynamics in both the political and the economic spheres. Relying on various new archival sources, it analyzes the conflicting effects on Italy of both the relaxing of Cold War tension and bipolarism, and the 'bipolar' strategy to reassert US hegemony: the failure of the reformist design of the center?-?left of the 1960s; the 'strategy of attention' in 1969?-?71 and its sudden halt; the building of a 'devaluation model' after the end of Bretton Woods, and the consequent shift from Kissinger's neo-centrism to 'national solidarity'. Détente favoured a crisis of the centrist pattern of Italian politics but at the same time the 'bipolar' features of both the US and the Soviet 'strategies of détente' led to a decline in US hegemony, relaunching the DC's centrality and its ability to manage external constraints. Reaganism was to recast US hegemony on a new basis.  相似文献   
100.
产业转型期的长三角区域海洋旅游特色产品链构建   总被引:1,自引:0,他引:1  
马丽卿  胡卫伟 《人文地理》2009,24(2):125-128
长三角地区是我国综合实力最强的经济中心,这一地区海岸线漫长,海洋旅游资源丰富,具备了发展旅游的资源、需求、区位和产品四大优势,是重要的旅游目的地和旅游客源地。近年来,长三角地区的入境旅游增长幅度逐年下降,旅游经济在国民经济体系、对外经济体系和服务经济体系中的比重也正发生着变化,旅游业面临着转型。作为现代服务业的旅游业是无边界产业,它与其它行业的广泛融合、相互渗透,形成了多样化的产业新形态。本文剖析了长三角地区转型时期的旅游产业,分析该区域旅游产业的新形态,并提出了构建海洋特色旅游产品链的设想。  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