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   203篇
  免费   13篇
  2024年   1篇
  2023年   3篇
  2022年   3篇
  2021年   4篇
  2020年   9篇
  2019年   9篇
  2018年   16篇
  2017年   16篇
  2016年   15篇
  2015年   6篇
  2014年   4篇
  2013年   39篇
  2012年   7篇
  2011年   8篇
  2010年   13篇
  2009年   13篇
  2008年   4篇
  2007年   4篇
  2006年   7篇
  2005年   14篇
  2004年   2篇
  2003年   2篇
  2002年   2篇
  2001年   2篇
  1999年   2篇
  1998年   2篇
  1996年   1篇
  1993年   1篇
  1992年   1篇
  1991年   1篇
  1990年   1篇
  1988年   1篇
  1985年   1篇
  1984年   1篇
  1978年   1篇
排序方式: 共有216条查询结果,搜索用时 15 毫秒
71.
The microstructure and chemical composition of blue cakes, found during the archaeological excavation of the Ayanis fortress (Eastern Anatolia, Turkey), have been investigated by means of scanning electron microscopy combined with energy dispersive spectrometry (SEM–EDS), X-ray diffraction (XRD), micro-Raman (μ-Raman) and optical microscopy (OM) techniques. The analysis of the Ayanis cakes has shown the presence of Egyptian blue (i.e. CuCaOSi4O10, cuprorivaite), as the major component, intermixed with minor amount of other phases such as partially reacted quartz grains, an adherent glass phase and copper oxides. Since the finding of Egyptian Blue in Turkey has been never reported so far, great attention has been paid to its characterisation. The micro-chemical and micro-structural investigations of the Ayanis cakes have allowed a further insight into the manufacturing process and into the sources of the starting materials. The results of the characterisation have revealed some significant differences with respect to Egyptian blue cakes found in Egypt and Mesopotamia, as for instance the absence of tin excluded the use of bronze scraps or filings in their preparation differently from those produced in Egypt and Mesopotamia. Furthermore, some peculiarities of Egyptian blue found in Ayanis, as the detection of zinc in the cakes, allow to put forward the hypothesis of a local production considering that a large part of the bronze artefacts found at the Ayanis fortress is characterised by the presence of zinc as minor alloying element.  相似文献   
72.
Abstract

By 1735, Jean-Baptiste Bourguignon d’Anville had produced forty-one maps of the Qing Empire, or China, a process significantly more complex than scholars have hitherto appreciated. A close study of d’Anville’s maps and their originals has revealed their relationship with the different versions of a Chinese atlas, the first of which was completed early in 1718, the outcome of nearly a decade of collaborative surveying between officials of the Qing Empire and European missionaries. The precise origins of some of the maps are identified for the first time, and the network behind the remarkable intercontinental exchange of cartographical material that allowed d’Anville to produce his China maps is also discussed, thereby illustrating the central role of the French Jesuits, as well as the connection with St Petersburg.  相似文献   
73.
A simple and general method based on well-known random vibration theory is used to compute spectral attenuation relations at soft sites based on existing spectral attenuation relations at rock sites. The method consists of: (1) computation, for given magnitude and distance, of the expected Fourier amplitude spectrum associated with the median rock response spectrum computed with the attenuation relation; (2) inclusion of site effects characterized by a frequency-dependent, linear, or nonlinear transfer function; and (3) computation of the response spectrum at the soft site.  相似文献   
74.
Di Martino, E., Taylor, P.D., Fernando, A.G.S., Kase, T. & Yasuhara, M. 3 June 2019, 2019. First bryozoan fauna from the middle Miocene of Central Java, Indonesia. Alcheringa 43, 461–478. ISSN 0311-5518.

Despite the publication of several taxonomic studies during the last few years, our knowledge of bryozoans from the diversity hotspot of the Indo-West Pacific remains seriously deficient. Here we describe 11 bryozoan species, comprising two anascan- and nine ascophoran-grade cheilostomes, from the middle Miocene (Langhian–Serravallian) of Sedan in Central Java, Indonesia. Three ascophoran-grade cheilostomes, Characodoma multiavicularia sp. nov. Di Martino & Taylor, Stenosipora? cribrata sp. nov. Di Martino & Taylor and Lacrimula patriciae sp. nov. Di Martino & Taylor, are described as new species. All of the three extant species have an Indo-Pacific distribution today and two are here reported as fossil for the first time. Four species are left in open nomenclature, either because of the scarcity of available material or the absence of crucial morphological features. Two of these, placed in Cosciniopsis and Actisecos, are likely to be new, while Discoporella sp. represents the easternmost known record for this common free-living genus. A single species, Lacrimula asymmetrica Cook & Lagaaij, was already known from the early Miocene of the same region, although from a site further to the east.

Emanuela Di Martino* [], Department of Earth Sciences, Natural History Museum, Cromwell Road, London SW7 5BD, UK; Paul D. Taylor [], Department of Earth Sciences, Natural History Museum, Cromwell Road, London SW7 5BD, UK; Allan Gil S. Fernando [], National Institute of Geological Sciences, The University of Philippines, Diliman, Quezon City, Philippines; Tomoki Kase [], National Museum of Nature and Science, Tsukuba, Japan; Moriaki Yasuhara [], School of Biological Sciences, Swire Institute of Marine Science, University of Hong Kong, Kadoorie Biological Sciences Building, Pokfulam Road, Hong Kong SAR, PR China  相似文献   
75.
The changes in the subsistence systems of riberenos, riparian inhabitants, occupying a blackwater river community in Peru's northeastern Amazonia are examined. The riberenos' traditional livelihood has been based on farming as well as the hunting and collecting of forest products. Their increasing dependence upon the market economy is, however, radically transforming the riberenos' swidden-agroforest system and other established rainforest management practices and, in the process, upsetting the environmental balance.  相似文献   
76.
The damaging effects of sea salt aerosols on Globigerina Limestone are well known, and various professionals have studied and reported on the often complex underlying deterioration mechanisms. Following a preventive conservation project, undertaken to shelter and protect the UNESCO World Heritage Neolithic temple sites of Hagar Qim and Mnajdra, the Preventive Conservation Unit within the Diagnostic Science Laboratory at Heritage Malta embarked on a pilot study to identify whether sea salt aerosol deposition patterns within the site alter significantly post sheltering. The results from this short pilot study, by identifying the presence of salts using ion chromatography, have shown that there is a consistent pattern that when directly linked to the intrinsic shape of the temple interior as well as to the micro-environmental factors that are changing as a direct result to the sheltering, point to the trends of greater pollutant accumulation, particularly dust.  相似文献   
77.
Abstract

The extraordinary nature of Garibaldi's life is reflected in his involvement in parliamentary activities across a number of countries (Uruguay, Kingdom of Sardinia, Roman Republic, Kingdom of Italy, French Republic). After the national unification, Parliament became a kind of great sounding board in Garibaldi's strategy thanks in part to the fact that in the Chamber he could count on a group of followers who were always ready to support any issue vaguely to do with memories of the Risorgimento or irredentist aspirations. His failure to steer the new state in the desired direction through the legislative process certainly influenced Garibaldi's negative opinion of parliamentary work. Garibaldi could not however recognize as an expression of popular sovereignty a parliament in whose election only 2 per cent of the population were allowed to participate. His main political battle was the fight for universal suffrage which was intended to enfranchise all Italians, thus turning subjects into citizens and finally making parliamentary institutions nationally representative and democratically legitimate.  相似文献   
78.
79.
<秘殿珠林石渠宝笈>是一部著录清代宫廷收藏书画的巨著,对书画鉴藏及艺术史研究具有重要参考价值.本文通过征引史料,对其编纂人员、编纂过程、编纂体例及版本情况详作考述,并讨论了<石渠宝笈>初编版本和内容的变化情况.  相似文献   
80.
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