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   1273篇
  免费   32篇
  2024年   4篇
  2023年   13篇
  2022年   17篇
  2021年   19篇
  2020年   31篇
  2019年   49篇
  2018年   50篇
  2017年   51篇
  2016年   53篇
  2015年   29篇
  2014年   45篇
  2013年   159篇
  2012年   76篇
  2011年   48篇
  2010年   64篇
  2009年   55篇
  2008年   61篇
  2007年   69篇
  2006年   60篇
  2005年   70篇
  2004年   51篇
  2003年   40篇
  2002年   43篇
  2001年   40篇
  2000年   37篇
  1999年   16篇
  1998年   14篇
  1997年   6篇
  1996年   7篇
  1995年   8篇
  1994年   6篇
  1993年   3篇
  1992年   6篇
  1991年   3篇
  1990年   1篇
  1982年   1篇
排序方式: 共有1305条查询结果,搜索用时 15 毫秒
1.
We analyze the response of municipalities to the occurrence of natural disasters in terms of spending behavior, use of upper-tier transfers and recovery, using balance sheet data of about 8,000 Italian municipalities for the period 2000–2015, and the universe of earthquakes events. We find evidence of increasing expenditure for about 12 years after the shocks, with asymmetric responses between earthquake-related and unconditional grants, and heterogeneous flypaper effects across the country. While in northern municipalities expenditure tends to regress to pre-earthquake levels, southern municipalities stick to higher expenditure levels when grants drop. This evidence is coupled with a faster recovery of private income and housing prices in northern municipalities.  相似文献   
2.
本文对青海古代各历史时期的文化遗址及文物进行了分析与探讨,提出了青海古代文化遗址有着分布的集中性、石器时代的完整性以及多元结构的民族文化特点;论证了以上特点是由地理环境及历史的各民族文化活动所致。  相似文献   
3.
迄今已有2 700多年历史的铜鼓,是南方少数民族地区节日、喜庆、兵事、婚丧、祭祀、礼乐等场合使用的一种重器。为了对锈蚀状况做出科学的现状评估,为器物保护修复技术路线的制定和修复工作的开展提供科学指导,对玉林市博物馆馆藏7件铜鼓综合运用了体视显微镜、金相显微镜、激光显微拉曼光谱仪(RS)和环境扫描电镜及能谱仪(ESEM-EDAX)等仪器进行了金相组织和合金成分分析以及锈蚀产物的分析。分析结果显示:7件器物皆为泥范铸造成型,未见热、冷加工处理现象。7件铜鼓皆为铅锡青铜合金,总体呈低锡高铅的特点。组织形态呈典型α固溶体树枝晶偏析,锡含量处于6.0%~12.2%,分布较为集中,处于中等含量水平(5%≤Sn15%);铅含量处于14.4%~28.2%,铅含量普遍较高且分布较为集中,处于中高铅(10%≤Pb15%)和高铅含量(Pb≥15%)水平,合金中高铅含量配比应为工匠有意合金配比选择;铜鼓的腐蚀类型为α固溶体富铜相优先腐蚀,保存环境主要是富氧、少氯,铜鼓表面锈蚀产物主要为绿色孔雀石和蓝色蓝铜矿以及氧化物,有少量白色白铅矿。在保护修复工作中对于这些无害锈可保留,不予处理,并注重防氧。对于铜鼓表面夹杂泥土,需进行清洗去除。研究结果可为器物保护修复技术路线的制定和修复工作的开展提供科学指导。  相似文献   
4.
We analyze the general equilibrium effects of an asymmetric decrease in transport costs, combining a large-scale spatial dynamic general equilibrium model for 267 European NUTS-2 regions with a detailed transport model at the level of individual road segments. As a case study, we consider the impact of the road infrastructure investments in Central and Eastern Europe of the European Cohesion Policy. Our analysis suggests that the decrease in transportation costs benefits the targeted regions via substantial increases in gross domestic product (GDP) and welfare compared to the baseline, and a small increase in population. The geographic information embedded in the transport model leads to relatively large predicted benefits in peripheral countries such as Greece and Finland, which hardly receive funds, but whose trade links cross Central and Eastern Europe, generating profit from the investments there. The richer, Western European nontargeted regions also enjoy a higher GDP after the investment in the East, but these effects are smaller. Thus, the policy reduces interregional disparities. There are rippled patterns in the predicted policy spillovers. In nontargeted countries, regions trading more intensely with regions where the investment is taking place on average benefit more compared to other regions within the same country, but also compared to neighboring regions across an international border. We uncover that regions importing goods from Central and Eastern Europe enjoy the largest spillovers. These regions become more competitive and expand exports, to the detriment of other regions in the same country.  相似文献   
5.
In this paper, we develop a three-region economic geography model with workers of heterogeneous skills and mobility rates to consider how first-nature, regional differences impact both inter- and intraregional inequality. In our model, the skill premium within a region summarizes both the degree of intraregional inequality between mobile, skilled workers and immobile, unskilled workers and the interregional inequality through differences in the welfare of unskilled workers across regions. Regions with the highest skill premium have the greatest degree of intraregional inequality and provide the lowest level of welfare to unskilled workers, relative to other regions. We find that the skill premium will be higher in regions with a greater supply of unskilled labor, lower supply of housing, or are more remote. An increase in a region's housing supply or centrality will lower intraregional inequality and raise the welfare of the local, unskilled workforce. However, the magnitude of these changes are declining in the initial number of skilled workers in the region. The model is extended to consider imperfectly elastic housing supply. The larger the price elasticity of housing, the larger the range of values, such that more populated regions will host a disproportionate share of skilled workers, have lower levels of intraregional inequality, and provide higher levels of welfare for unskilled workers.  相似文献   
6.
In recent years, cultural anthropologists have made notable progress in understanding the bewildering variety of material exchange transactions found among the aboriginal populations of highland New Guinea. One of the major findings of this work is that competitive exchange behavior may bring in its wake alterations in agronomic practices involving an intensification of production. That intensification is primarily a product of social behavior, rather than an adaptation to climate change or population pressure, is a significant conclusion that should influence the thinking of archaeologists as they investigate past episodes of agronomic change, including the origins of agriculture.  相似文献   
7.
本文采用因子生态分析方法剖析多伦多都市区的居住空间结构。主成分分析表明,家庭构成、年龄构成、职业构成是形成城市居住分异的主要因素。聚类分析表明,家庭构成和年龄构成的分异呈同心园格局,职业构成的分异呈扇形格局。形成这种居住分异格局的机制包括动力机制、管理机制和行为机制三个方面。  相似文献   
8.
New industrial innovation policies like smart specialization aim at boosting economic growth by diversification towards more complex and higher value economic activities. This paper proposes a conceptual and analytical framework to support the design and implementation of such policies considering place-specific preconditions, particularly the differentiation of the regional system of innovation and entrepreneurship and the degree of current industrial diversification. The paper expands on the links between these preconditions and the barriers and opportunities for industrial diversification. Consequently, it proposes an archetypical place-based policy framework covering overall policy objectives as well as measures at the level of actors, networks, and the institutional and organizational support structures.  相似文献   
9.
This paper aims to introduce a case study of Czechia in distribution of the EU funds and their spatial patterns. EU funds receive plenty attention from both European society and the scientific community. However, there is a lack of detailed evaluations of spatial and sectoral differentiation, which might bring a better understanding to the whole EU funds system. This paper attempts to fill this gap with a method of geographical differentiation analysis of the Czech operational programme Enterprise and Innovations 2007–15, which should increase the competitiveness of industry and develop services for commercial activities. Historically, subsidies often go to peripheral regions at the borderland with Slovakia and Poland, while regions along the borders with Germany and Austria receive only a low level of support. Jurisdictions of the major recipients from hi-tech sectors are mainly in the close vicinity of the largest cities (Praha, Brno), which are natural centres of high technologically demanding sectors, but a high share of high-tech subsidies goes to some peripheral districts as well. These findings can contribute not only to the academic discussion about contradictory developmental impacts of subsidies but to the all-European debate on the EU funds purposes as well.  相似文献   
10.
位于四川省阆中市的大像山石窟,主要开凿于中晚唐和宋代,明清时期也有少量开凿。现有37龛,以方形龛、外方内圆拱形龛及圆拱形龛为主,方形龛最为多见。龛楣大多无装饰,雕刻简单。题材主要有弥勒佛、七佛、千佛、观音、天王、力士、经幢及舍利塔等。造像组合较少,以单身造像为多。阆中独特的地理位置,使得大像山石窟兼具广元、巴中两地石窟的特点,其丰富的内容为巴蜀佛教石窟寺的深入研究提供了重要的实物资料。  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