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   7888篇
  免费   110篇
  7998篇
  2020年   106篇
  2019年   128篇
  2018年   186篇
  2017年   204篇
  2016年   250篇
  2015年   172篇
  2014年   159篇
  2013年   2006篇
  2012年   200篇
  2011年   255篇
  2010年   227篇
  2009年   210篇
  2008年   191篇
  2007年   161篇
  2006年   155篇
  2005年   107篇
  2004年   111篇
  2003年   80篇
  2002年   88篇
  2001年   117篇
  2000年   109篇
  1999年   106篇
  1998年   78篇
  1997年   89篇
  1996年   65篇
  1995年   70篇
  1994年   69篇
  1993年   83篇
  1992年   76篇
  1991年   81篇
  1990年   63篇
  1989年   70篇
  1988年   62篇
  1987年   90篇
  1986年   61篇
  1985年   96篇
  1984年   91篇
  1983年   110篇
  1982年   82篇
  1981年   87篇
  1980年   95篇
  1979年   80篇
  1978年   83篇
  1977年   107篇
  1976年   95篇
  1975年   79篇
  1974年   70篇
  1973年   62篇
  1972年   57篇
  1971年   53篇
排序方式: 共有7998条查询结果,搜索用时 0 毫秒
61.
62.
Feature Reviews     
Abstract

Liberal education has a real, if precarious, place in America. Its purpose is to remind each of us that were all more than middle-class, more than beings with interests or rights. American liberal education finds its resources in classical and Christian thought, both European and indigenous. The main challenge to liberal education today comes from the libertarians.  相似文献   
63.
Canada hosts two major diversified biotechnology regional systems of innovation in its two largest cities. Similar in many respects, they display some particular characteristics. We review here the main theories on regional innovation systems and innovative clusters and proceed to analyse these two regional systems before concluding on the usefulness of several theories to study biotechnology regional innovation systems.|spagf|ro|epagf|  相似文献   
64.
This article explores a series of tensions inherent in the series of European policies that are designed to improve the competitiveness of regions in the face of globalization. Its focus is the co-existence of interventionist policies intended to overcome problems of lagging regions such as cohesion policies and those, for example competition policy which are designed to remove barriers to market integration and that are anti-interventionist. Moreover, the changing relationship between the European Union (EU), member states and the regions and problems of how regions are defined complicate policy implementation. To review these issues, the article adopts an agent-centred approach to understanding economic behaviour in the face of globalization in particular geographical and sectoral contexts. This methodology is used to highlight five sources of tension relating to the reality of the experience of globalization. These are illustrated by evidence from a recently completed EU Fifth Framework Programme study of regional adjustment strategies and technological change in five European countries.  相似文献   
65.
Samples of Roman thin‐walled ware from Segesta (northwestern Sicily), dating back to the early Imperial period, were studied by optical microscopy (OM) and Neutron Activation Analysis (NAA). Up to now, this class of Roman fine tableware has only occasionally been evaluated archaeometrically. Nevertheless, numerous production centres are believed to have been simultaneously active in the western Mediterranean area. Petrographic and chemical data seem to be in agreement with the archaeological hypothesis of local manufacture in Segesta for most of the analysed samples, through a comparison with kiln wasters and local raw materials. The effectiveness of thin‐section petrography for determining the provenance of such a tiny tempered class of pottery and the integrated use of two different grouping procedures (petrography and chemistry) were also tested.  相似文献   
66.
The authors urge a zonal specialization of agriculture within the countries of the Socialist camp, particularly the CEMA grouping. Bulgaria, which supplies tobacco, grapes, early vegetables, and fruits to other countries, in cited as an example. Geographers are urged to work out such a specialization scheme based on a complex of factors, including the physical-geographic base, manpower resources, the present state of agriculture, and the traditional working habits of the population.  相似文献   
67.
Pierre Marie was a prominent member of the French neurological world of the early twentieth century. Having been trained by the celebrated physician, J-M Charcot, Marie remained influenced by his teacher throughout his career. Because of this influence, his career can be logically divided into three phases: first, the early years under the direct mentorship of Charcot (1878-1893); secondly, the aftermath of Charcot’s death when Marie left his teacher’s institution, the Salpêtrière hospital and established himself at the Bicêtre hospital in southern Paris (1893-1918); and finally, Marie’s return to the Salpêtrière to assume the original Charcot chaired professorship, albeit as an aged man (1918-1925). This essay examines Marie’s career with an emphasis on documentation of the combined attributes of a gifted intellect as well as a heated emotionality. In the context of his time, these elements prompted Marie to enter into controversies and medico-political battles that advanced neurological knowledge, but likely disadvantaged him in his career successes.  相似文献   
68.
69.
SUMMARY: In 2014, during construction work at the ex-Civil Hospital in Gibraltar, excavations led by the Gibraltar Museum revealed a major, previously unknown burial ground containing more than 200 skeletons. We present the historical, archaeological and radiometric dating evidence from the site alongside the results of initial osteological analyses. The data indicate that the burials pertain to an earlier 16th-century Spanish hospice, and therefore stand to offer new insights into the functioning of this early modern hospital and the health and movements of people at a time of incipient globalization.  相似文献   
70.
The environmental impact of copper-smelter emissions in a southern taiga landscape is analyzed in terms of three concentric zones: (1) an inner zone of total environmental disruption; (2) a zone of heavy modification; (3) a zone of slight modification. The changes in vegetation cover resulting from the emissions are described for each zone. [The study area is not identified beyond being in Chelyabinsk Oblast of the southern Urals, but the context makes clear that the paper deals with the copper smelter of Karabash, a town with a population of 20,000, 50 miles northwest of Chelyabinsk–Editor, S.G.] A related article on smelter pollution in the taiga appeared in Soviet Geography, April 1977.  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