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   520篇
  免费   52篇
  2024年   2篇
  2023年   14篇
  2022年   8篇
  2021年   5篇
  2020年   20篇
  2019年   25篇
  2018年   62篇
  2017年   52篇
  2016年   55篇
  2015年   33篇
  2014年   41篇
  2013年   101篇
  2012年   22篇
  2011年   16篇
  2010年   16篇
  2009年   18篇
  2008年   11篇
  2007年   8篇
  2006年   5篇
  2005年   5篇
  2004年   8篇
  2003年   3篇
  2002年   5篇
  2001年   2篇
  2000年   4篇
  1999年   2篇
  1998年   3篇
  1996年   4篇
  1995年   3篇
  1994年   2篇
  1993年   3篇
  1992年   3篇
  1989年   1篇
  1988年   2篇
  1987年   1篇
  1985年   2篇
  1984年   1篇
  1982年   1篇
  1981年   1篇
  1973年   1篇
  1950年   1篇
排序方式: 共有572条查询结果,搜索用时 343 毫秒
101.
The cliff in Ustka is an active one. The area is one of the most eroded sea shores of the Polish coast. The Ustka Cliff mainly consists of Holocene sandy deposits, but its basis is built of glacial till and clay. Field search allowed to recognize the structure and sedimentary conditions of Holocene deposits exposed in the cliff. A comparison of dating results obtained for fossil soils and peat as well as aeolian deposits, using 14C and TL methods, respectively, with available literature records is presented. The evaluation of results obtained allowed to define three main dune-forming phases for the first time for this part of the Polish coast. During the research studies new data on the processes and environmental conditions was gained and the development of structure of the area during the last 10 thousand years was reconstructed. The analysis of available data from other sections of the southern Baltic coast shows that results obtained are age similar to those determined for the ?eba Spit. The research is part of a project concerning the geomorphology of the Ustka Bay.  相似文献   
102.
This article presents a preliminary attempt to characterise Upper Thai-Malay Peninsula prehistoric iron technologies based on assemblages from two recently excavated coastal sites: Khao Sam Kaeo and Phu Khao Thong. These are the earliest known sites involved in the early trans-Asian exchange that connected the eastern Indian Ocean to the South China Sea from the mid-first millennium bc. It is from this period that iron assemblages start appearing at both continental and insular Southeast Asian sites. Three models have been offered confronting an indigenous vs. Chinese or South Asian impetus for the introduction of iron metallurgy in Southeast Asia. These models are discussed in the light of the metallographic and compositional analyses of iron and slag assemblages from these two sites using optical microscopy, scanning electron microscopy with energy dispersive spectrometry, energy dispersive X-ray fluorescence and slag inclusion analysis techniques, together with other production materials from these and other contemporaneous Southeast Asian sites.  相似文献   
103.
104.
Journal of Archaeological Method and Theory - Fish taphonomy from archaeological sites provides considerable useful information about human behaviours and environmental contexts as potential food...  相似文献   
105.
Many data sets collected for study areas consist of data values collected on a square lattice or for a set of pixels. Remotely sensed data provide perhaps the most common example. Frequently, we wish to know whether there are subregions of the study area that exhibit spatial clustering. In this article, we suggest how an approach for finding spatial clusters may be combined with the common practice of using 3‐by‐3 and 5‐by‐5 smoothing filters or kernels to construct two simple and easy‐to‐implement scan‐type tests. A simulation experiment shows that the power of these tests to find clusters compares favorably with an alternative test that is more complicated. The tests use simulated data, changes in a remotely sensed image for a study region in Texas, and data about wheat yields. Muchas bases de datos que se recopilan para una zona de estudio, consisten en valores recopilados en una retícula cuadrada o en un conjunto de pixeles. Los datos obtenidos por sensores remotos son quizá el ejemplo más común. Frecuentemente deseamos saber si existen subregiones de la zona de estudio que exhiban agrupamiento espacial. En este artículo, sugerimos cómo una aproximación para ubicar agrupamientos espaciales se puede combinar con la práctica común de usar filtros de suavizado (kernels) de 3‐por‐3 y 5‐por‐5 filtros, para construir dos test tipo scan, sencillos y fáciles de implementar. Un experimento de simulación demuestra que el poder de estas pruebas para ubicar agrupamientos, se compara favorablemente frente a otra prueba alternativa, que resulta más complicada. Las pruebas usan datos simulados, cambios en una imagen de satélite para un área de estudio en Texas, y con data acerca de los rendimientos de cultivos de trigo. 研究区收集的许多数据集是由基于方格网和像素采集的数据值组成的,遥感数据可能提供了最常见的范例。通常,我们希望了解研究区的子区域是否呈现空间集聚特征。本文提出了一种如何发现空间集聚的方法,可以与采用3*3和5*5平滑滤波或核函数的普通试验相结合,构造两个简单且易于操作的扫描试验。模拟实验结果显示,这些试验在寻找聚集特征的性能上优于更复杂的可替换性试验。文中所用的仿真模拟数据来源于德克萨斯州小麦产量的多时相遥感影像。  相似文献   
106.
107.
108.
109.
The Musée du Quai Branly, located beside the Eiffel Tower in Paris, opened in June 2006. Constructed to house France's important collection of non-western art, the museum has been promoted as ‘decidedly post-colonial’ and a place of ‘reconciliation and sharing’. Historians have situated the creation of the museum within political debates over the restructuring of several of France's museums and, more broadly, the country's position in a post-colonial world, while focusing little critical attention on the building itself. The author argues that Jean Nouvel's architectural program for the Musée du Quai Branly—a ‘primitive shelter’ surrounded by a ‘sacred wood’—gives physical form to a primitivist aesthetic. The unproblematised binaries of self versus other and culture versus nature evident in Nouvel's design reveal a surprisingly unsophisticated theoretical standpoint. As a frame in which to view and understand the objects on display, the Musée du Quai Branly invites a primitivist—and colonial—reading of its collection.  相似文献   
110.
Abstract

Multiple sclerosis (MS) was first presented in a clinical setting in 1838. In this paper the presentation and treatment of a transient hemiparesis in a drummer in 1789 is discussed. This may have been an early case of MS and presents evidence against the theory that MS is an infectious disease beginning in the 19th century.  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