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   1905篇
  免费   84篇
  2020年   25篇
  2019年   26篇
  2018年   47篇
  2017年   55篇
  2016年   61篇
  2015年   55篇
  2014年   38篇
  2013年   651篇
  2012年   62篇
  2011年   59篇
  2010年   81篇
  2009年   70篇
  2008年   40篇
  2007年   82篇
  2006年   70篇
  2005年   22篇
  2004年   38篇
  2003年   29篇
  2002年   25篇
  2001年   22篇
  2000年   17篇
  1999年   21篇
  1998年   19篇
  1996年   12篇
  1995年   22篇
  1994年   15篇
  1993年   9篇
  1992年   12篇
  1991年   9篇
  1990年   9篇
  1989年   12篇
  1988年   14篇
  1987年   18篇
  1986年   12篇
  1985年   19篇
  1984年   17篇
  1983年   12篇
  1982年   13篇
  1981年   14篇
  1980年   16篇
  1979年   14篇
  1978年   11篇
  1977年   8篇
  1976年   9篇
  1975年   9篇
  1974年   8篇
  1973年   9篇
  1972年   12篇
  1971年   8篇
  1970年   9篇
排序方式: 共有1989条查询结果,搜索用时 15 毫秒
21.
22.
23.
ABSTRACT. Traditional models of regional diversification do not capture the trade-off between stability and living standards. In this paper, we characterize regions as open activity models subjected to both productivity and price shocks. We then partially rank small diversification policies by the direction in which they point away from the current industrial structure in mean-variance space. Some general patterns emerge. In particular, diversification for regional self-sufficiency and away from regional comparative advantage may be undesirable.  相似文献   
24.
This paper analyses the results of a survey of twenty-four recent cases of technology imports into India. Over the last thirty years, large firms in Indian industry have come under increasing competitive pressure from small firms which pay lower wages and which are also favoured by government policy. Most small firms obtain technology through informal channels within the country. But some import technology; and larger firms import it in their defence against competition from small firms. Larger firms, with a history and a reputation, have better access to technology from abroad; smaller firms often go through an extensive search before they find a willing technology supplier. Irrespective of size, firms that import technology within their own specialization are observed to put more effort into technology choice, absorption and adaptation. Indian policies of across-the-board import substitution, by promoting diversification into new products developed abroad, tend to discourage specialization and hence to encourage technology imports and to work against technology absorption and innovation.  相似文献   
25.
African Archaeological Review - A set of beads made of glass, gastropod mollusk shell, and fishbone from a Swahili occupation level on Ibo Island (northern Mozambique) is dated to the eleventh and...  相似文献   
26.
The study addresses the chemical variations for Roman Samian wares manufactured during various periods at different workshops within the Lezoux production centre. Instrumental neutron activation analysis and inductively coupled plasma spectrometry were used to determine the chemical constituents of the pottery. The two techniques were evaluated based on the capacity of each to identify the same compositional groups for Lezoux Samian with the use of multivariate statistics. The compositional analysis redefines and clarifies how potters used the clay sources at the site to produce fine wares. The results indicate that the majority of potters from different workshops at Lezoux shared the same clay source during the second century AD.  相似文献   
27.
Blue glass trade beads from well-dated late seventeenth- to early twentieth-century sites and collections have been analysed non-destructively by instrumental neutron activation analysis. The beads display enough variations in their elemental contents to allow us to characterize the different chemistries. The implication of these results is that similar chemical analyses of blue beads from undated archaeological sites may be used to help date the sites, since each bead chemistry has a specific earliest period.  相似文献   
28.
Fifty-three copper-based metal fragments, recovered from the Robitaille site in southcentral Ontario, were analysed by neutron activation to establish their chemical make-up and to sort them by their trace elemental chemistries. Three different European copper samples, one brassy copper and 48 brass samples with five different chemistries were found. As few as eight trading actions may account for all of the recovered European metal fragments.  相似文献   
29.
Current theoretical understanding of compliance with international law is based on an assumption that international law consists of a finite set of objective, compulsory rules. This image does not match reality but the two can be reconciled through theorising international law as ideology. Such an approach subsumes questions as to why states do or do not obey law and what influence international law has on foreign policy decision making. By placing the relationship of state behaviour to international law in a broader perspective it can account for previously identified determinants of compliance and provide a basis on which to assess their relative significance. At the same time, the research agenda regarding compliance is broadened by the introduction of fresh questions.  相似文献   
30.
The need for experiments to study physical aspects of craft of the past is stated, as well as the necessity for them to have clear aims and to follow the established principles of scientific enquiry. These principles are discussed in this joint paper by ten maritime archaeologists and others, together with methods and some points of management critical to their application in this field.  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