全文获取类型
收费全文 | 1226篇 |
免费 | 72篇 |
出版年
2024年 | 3篇 |
2023年 | 28篇 |
2022年 | 7篇 |
2021年 | 17篇 |
2020年 | 55篇 |
2019年 | 59篇 |
2018年 | 116篇 |
2017年 | 89篇 |
2016年 | 81篇 |
2015年 | 59篇 |
2014年 | 53篇 |
2013年 | 173篇 |
2012年 | 79篇 |
2011年 | 70篇 |
2010年 | 60篇 |
2009年 | 79篇 |
2008年 | 48篇 |
2007年 | 45篇 |
2006年 | 29篇 |
2005年 | 40篇 |
2004年 | 11篇 |
2003年 | 18篇 |
2002年 | 11篇 |
2001年 | 16篇 |
2000年 | 12篇 |
1999年 | 4篇 |
1998年 | 2篇 |
1997年 | 7篇 |
1996年 | 4篇 |
1995年 | 10篇 |
1994年 | 2篇 |
1993年 | 3篇 |
1992年 | 4篇 |
1991年 | 1篇 |
1982年 | 1篇 |
1979年 | 1篇 |
1962年 | 1篇 |
排序方式: 共有1298条查询结果,搜索用时 15 毫秒
101.
We present experimental data examining the energetics and identification of axial bipolar reduction in contexts of lithic miniaturization on milky quartz. These experiments answer two specific questions. First, does bipolar reduction provide any benefits over freehand reduction? Second, can axial bipolar reduction be distinguished from freehand reduction? Our data show that bipolar reduction requires significantly less time to reduce a percentage unit of core mass and to produce a millimeter of cutting edge on milky quartz than freehand reduction. Milky quartz bipolar reduction surpasses even the cutting edge production efficiency of obsidian pressure blades. We outline a series of quantitative criteria for identifying bipolar cores and flakes. Our results show that bipolar cores and flakes can be distinguished from those produced using freehand reduction by quantifying platform crushing, distal flake rebound scars, bulb shearing, as well as axial, bipolar, and splintered flake terminations. Our results challenge the widely held perceptions about the wastefulness of bipolar reduction and provide clear guidelines for identifying this reduction strategy in archaeological milky quartz assemblages. 相似文献
102.
Marta García-Alonso 《History of European Ideas》2017,43(4):331-344
ABSTRACTFor most interpreters of the philosopher from Rotterdam, his political doctrine is solely a consequence of his religious and moral doctrines, and so an image of Bayle as a political philosopher is not usually presented. To my mind, however, only by analyzing his political doctrine can the extent of his religious proposal be understood. In this article, I intend to show that both the Baylean criticism of popular sovereignty and his rejection of the right of resistance are analyses that are indissociable from the Baylean doctrine of tolerance. The protection of individual freedom of conscience and the defense of a multi-confessional state model, tolerant regarding religious minorities, can only be articulated as historical reality if they rest on the political doctrine of indivisible sovereignty and on the strictest separation between political obedience and religious membership. 相似文献
103.
104.
105.
A polyphasic tectonic‐fluid system of a fault that involves crystalline and carbonate rocks (Hospital fault, Barcelona Plain) has been inferred from regional to thin section scale observations combined with geochemical analyses. Cathodoluminescence, microprobe analyses and stable isotopy in fracture‐related cements record the circulation of successive alternations of hydrothermal and low‐temperature meteoric fluids linked with three main regional tectonic events. The first event corresponds to the Mesozoic extension, which had two rifting stages, and it is characterized by the independent tectonic activity of two fault segments, namely southern and northern Hospital fault segments. During the Late Permian‐Middle Jurassic rifting, these segments controlled the thickness and distribution of the Triassic sediments. Also, dolomitization was produced in an early stage by Triassic seawater at shallow conditions. During increasing burial, formation of fractures and their dolomite‐related cements took place. Fault activity during the Middle Jurassic–Late Cretaceous rifting was localized in the southern segment, and it was characterized by hydrothermal brines, with temperatures over 180°C, which ascended through this fault segment precipitating quartz, chlorite, and calcite. The second event corresponds to the Paleogene compression (Chattian), which produced exhumation, folding and erosion, favouring the percolation of low‐temperature meteoric fluids which produced the calcitization of the dolostones and of the dolomite cements. The third event is linked with the Neogene extension, where three stages have been identified. During the syn‐rift stage, the southern segment of the Hospital fault grew by tip propagation. In the relay zone, hydrothermal brines with temperature around 140°C upflowed. During the late postrift, the Hospital fault acted as a unique segment and deformation occurred at shallow conditions and under a low‐temperature meteoric regime. Finally, and possibly during the Messinian compression, NW‐SE strike‐slip faults offset the Hospital fault to its current configuration. 相似文献
106.
G. Huelga‐Suarez M. Moldovan M. Suárez Fernández M. Ángel de Blas Cortina J. I. García Alonso 《Archaeometry》2014,56(4):651-664
This paper continues the characterization of the lead isotopic fingerprint of ancient copper mines in the north‐west of Spain. In this work, the lead isotopic compositions found in copper ores from the La Profunda mine are presented. Azurites and malachites sampled from this deposit were subjected to lead isotope analysis by multicollector ICP–MS. The results showed a clear radiogenic lead signature compatible with the presence of uranium‐rich minerals (such as zeunerite) in the same mining complex. Moreover, a rare copper artefact, found in the galleries of the mine during its modern exploitation, was also analysed and showed that local mineral was used for its manufacturing. 相似文献
107.
Relying on stochastic frontier analysis we propose a methodology to study the technological characteristics and cost efficiency levels related to the provision of public infrastructure for basic utilities. The methodology assumes a cost minimizing behaviour on the part of public officials when planning the construction of local infrastructure, which is represented by way of a flexible translog cost function. Introducing relevant definitions of scale economies, associated with larger numbers of inhabitants and dwellings, as well as economies of density, brought about by reductions in urban dispersion, we analytically determine the optimal population densities for which average cost is minimized. We illustrate our model with the water cycle sector, including water distribution, sewage collection and cleansing of wastewater, and considering data at the municipality level for the Spanish region of Castilla y León. The obtained results indicate potential cost savings in the form of decreasing average costs, as relevant scale and density economies are present, along with large inefficiency levels. Relevant policy guidelines favouring larger and denser urban sizes are drawn, as the observed cost excess is the result of a general suboptimal urban size in terms of population density, and the negative effects of dispersed settlement patterns. 相似文献
108.
The reflection of human activity in the sediments of Iwankowskie Lake from Subatlantic Phase (Polish Outer Carpathians) 总被引:2,自引:0,他引:2
Anna Bucała Włodzimierz Margielewski Leszek Starkel Krzysztof Buczek Valentina Zernitskaya 《Geochronometria》2014,41(4):377-391
The paper presents the analysis of organic and mineral sediments filling the depression, which developed over the landslide located at the slope (767–773 m a.s.l.) of Lubań ridge decscending to the Ochotnica river valley in the Polish Flysch Carpathians. The landslide formed in an early stage of the Subatlantic Phase (2490 ± 35 BP). The top of peat is dated at 1360 ± 50 years BP and is covered by 72 cm of clayey silts with some sandy intercalations, which indicate slopewash after deforestation. The pollen of ruderal plants and Cerealia (undiff.) reflect agricultural activity in the surroundings. The fragments of charcoal indicate the age of the forest clearance to the first half of the 17th century. The late forest clearance at the elevated north exposed slopes followed 200–300 years later in relation to the foundation of the village at the valley floor. 相似文献
109.
一、导论春节“传统”是什么样子的?从文献到文献的抄录、对内在涵义的穷索将春节变成了专家学者的“内部知识”。研究者们忽视了的问题是,所谓的春节“传统”在普通的民众当中呈现出什么样的实践形态?他们的春节实践都是整齐划一的吗?是什么导致人与人之间在春节实践上的不同?即使是同一人的春节实践是否随着时间而变化?是什么影响了这些变化?他们如何看待这些不同和变化?本文拟使用与文献研究相别的另一种史料——口述史材料,主要以个人及其家庭实践的视角来观察1949~1989年之间的春节习俗变迁。 相似文献
110.
本文概括论述了成吉思汗经略西北边疆的出众文略,指出他组建新的依靠力量,经略中西驿路交通,短短几年便统一中国西北边疆,达到了建立欧亚帝国和促进人类古代最广大的一次“握手”的一代辉煌,以及成吉思汗处理西北民族关系和塑建开放性民族结构之成功。同时剖析了他因文化的局限性而造成的两大失误给他本人和子孙带来的悲剧。最后,剖析了领土观念、制度文化、利益依附关系如何成为边疆分裂的根本因素。 相似文献