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   3886篇
  免费   135篇
  2020年   46篇
  2019年   53篇
  2018年   92篇
  2017年   95篇
  2016年   116篇
  2015年   77篇
  2014年   69篇
  2013年   1103篇
  2012年   98篇
  2011年   131篇
  2010年   113篇
  2009年   94篇
  2008年   97篇
  2007年   65篇
  2006年   67篇
  2005年   63篇
  2004年   55篇
  2003年   32篇
  2002年   38篇
  2001年   61篇
  2000年   49篇
  1999年   57篇
  1998年   38篇
  1997年   43篇
  1996年   38篇
  1995年   30篇
  1994年   37篇
  1993年   42篇
  1992年   44篇
  1991年   35篇
  1990年   29篇
  1989年   36篇
  1988年   35篇
  1987年   45篇
  1986年   30篇
  1985年   48篇
  1984年   37篇
  1983年   65篇
  1982年   48篇
  1981年   55篇
  1980年   54篇
  1979年   38篇
  1978年   40篇
  1977年   58篇
  1976年   42篇
  1975年   44篇
  1974年   31篇
  1973年   29篇
  1972年   26篇
  1971年   33篇
排序方式: 共有4021条查询结果,搜索用时 31 毫秒
1.
2.
The deposition of Early Neolithic material within tree-throw hollows in described, and the possible role of fallen trunks as places of occupation, settlement foci and landscape markers is discussed. Having implications for the interpretation of ubiquitous later Mesolithic pit dwellings, the evidence suggests a continuity of forest 'identity'. Accordingly, patterns of clearances are also explored in relationship to modes of occupation, and the employment of 'big wood' in Neolithic monuments discussed.  相似文献   
3.
Trigger levels for fine suspended sediment (FSS) load in streams are required to identify rainfall-runoff events that have significantly elevated FSS loads, compared with expected background loads, as a result of catchment disturbance. Stream FSS load data collected in the mine-impacted Magela Creek catchment in the wet-dry tropics were used to derive water quality management trigger levels for two approaches – a Before-After-Control-Impact Paired difference design (BACIP) and a regression relationship between observed FSS load and corresponding event discharge characteristics. The results indicate that both the BACIP and regression relationship approaches behave similarly, with similar FSS load events elevated above trigger levels. Notwithstanding this, it is recommended that in order to reliably assess the location and magnitude of a catchment disturbance on FSS load, a combination of BACIP and regression relationship approaches must be adopted. In this study, an event with a FSS load above trigger levels associated with both BACIP and the regression relationship fitted for the downstream site is considered to be significantly elevated as a result of a disturbance within the mine-impacted region. While this technique cannot conclusively determine whether the cause of the disturbance is mine-related or natural (such as fire or bank erosion), it is an efficient statistical method of identifying events that warrant further investigation and management action, if required.  相似文献   
4.
5.
6.
We apply X-ray fluorescence (XRF) geochemical analysis to a collection of 'Opunohu Valley lithic artifacts from Mo'orea island to investigate the local scale of raw material procurement, adze production, use, and exchange within the Society Island archipelago. We use these data to document the distribution of non-local versus local volcanic artifacts in 'Opunohu Valley house sites, ritual sites, and specialized sites, as a means for establishing intra-site production and consumption patterns, and access to exotic, possibly superior, stone resources, and how these two themes correlate with site function or household wealth and status. Overall, 30% of the artifacts analyzed via WDXRF derive from non-local sources, notably two other islands in the archipelago outside of the political boundaries of Moorean chiefdoms. Our case study thus provides the first direct material evidence of intra-archipelago trade and exchange in the Society Islands. Intra-archipelago trade in adzes was certainly in place by as early as A.D. 1350, if not earlier, and continued up until the time of European contact. In addition, our analyses have identified a local adze production locale in the Afareaitu district of Mo'orea island. The patterns of local versus non-local adze production and exchange strongly suggest that dual interaction spheres were involved. The correlation between adzes and adze-related debris produced from off-island sources and sites with specialized use, which were often reserved for the social, ritual, and political elites in Ma'ohi society suggests that some of the exotic adzes derived from gift exchange between Mo'orea and ruling elites in Tahiti and the Leeward Islands. These adzes from afar would have solidified socio-political and ideological alliances between elites in the Windward and Leeward sectors of the archipelago.  相似文献   
7.
8.
9.
Almost all of the obsidian used to craft stone tools in the Near East from the Palaeolithic onward originated from volcanoes in two geographic regions: Central Anatolia and Eastern Anatolia. Five decades of obsidian sourcing has led to the view that Central Anatolian obsidians largely followed the Mediterranean coast and rarely reached farther east than the Middle Euphrates, whereas Eastern Anatolian sources almost exclusively supplied sites east of the Euphrates. This paper discusses the identification of Central Anatolian obsidian artefacts at the Bronze-Age site of Tell Mozan (Urkesh) in northeastern Syria. Most of the obsidians at Tell Mozan (97%) came from the Eastern Anatolian sources, as expected from established distribution models. Artefacts of Central Anatolian obsidian, however, were excavated from one well-constrained context: the deposits on a palace courtyard that date to the height of the Akkadian empire's influence at this third-millennium Hurrian religious and political centre. In particular, the obsidian came from the Kömürcü source of Göllü Da?. Potential explanations for this exotic obsidian are discussed. This obsidian might have “piggybacked” on the distribution of Central Anatolian metals or arrived at this city as royal gifts or prestige items. Other discussed mechanisms include Akkadian-linked changes in either territoriality involving pastoral nomads responsible for the arrival of Eastern Anatolian obsidians or identity construction of elites based on involvement in Central Anatolian economic and political networks.  相似文献   
10.
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