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   206546篇
  免费   5256篇
  国内免费   642篇
财政金融   31015篇
工业经济   14238篇
计划管理   31137篇
经济学   37428篇
综合类   6288篇
运输经济   1321篇
旅游经济   2755篇
贸易经济   28728篇
农业经济   8685篇
经济概况   23727篇
水利工程   26702篇
信息产业经济   18篇
邮电经济   402篇
  2022年   1266篇
  2021年   2512篇
  2020年   2976篇
  2019年   3354篇
  2018年   3446篇
  2017年   3971篇
  2016年   4060篇
  2015年   3775篇
  2014年   5780篇
  2013年   18955篇
  2012年   8859篇
  2011年   10492篇
  2010年   9582篇
  2009年   8639篇
  2008年   8455篇
  2007年   7644篇
  2006年   8099篇
  2005年   7576篇
  2004年   5093篇
  2003年   4272篇
  2002年   4124篇
  2001年   3941篇
  2000年   3375篇
  1999年   3331篇
  1998年   2865篇
  1997年   2857篇
  1996年   2685篇
  1995年   2420篇
  1994年   2430篇
  1993年   2347篇
  1992年   2431篇
  1991年   2279篇
  1990年   2102篇
  1989年   1942篇
  1988年   1843篇
  1987年   1859篇
  1986年   1868篇
  1985年   2658篇
  1984年   2586篇
  1983年   2363篇
  1982年   2245篇
  1981年   2190篇
  1980年   2181篇
  1979年   2126篇
  1978年   1920篇
  1977年   1846篇
  1976年   1658篇
  1975年   1501篇
  1974年   1405篇
  1973年   1406篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
We collected 469 frontal face images of Ukrainian cabinet ministers who were in office in 2000–2020. For each image, the minister's body mass index was estimated using a computer vision algorithm. The time series of median estimated body mass index of cabinet ministers co-moves over time with two existing measures of corruption – World Bank worldwide governance indicator Control of Corruption, and the discrepancy between the quantity of luxury wristwatches exported from Switzerland to Ukraine (reported by Swiss statistics) and the corresponding quantity imported by Ukraine from Switzerland (reported by Ukrainian statistics).  相似文献   
2.
以我国各省知识产权保护制度为研究对象,创新性地将探索性空间数据分析方法与社会网络分析方法相结合,基于地理邻近视角,验证了区域知识产权保护的空间相关性、空间集聚特征和空间溢出效应。同时,突破地理近邻效应的局限,解析区域知识产权保护的空间关联特征。结果表明:我国各省知识产权保护具有全局自相关性,相似地区间存在空间集聚效应,不同发展程度地区的空间关联性质不同;网络化后的区域知识产权保护各节点间联系紧密、网络结构稳定,并且可以确定核心行动者和边缘行动者角色;长三角、珠三角、环渤海等较发达地区与其它地区之间存在较多溢出关系。  相似文献   
3.
马威 《价值工程》2021,40(23):174-176
导航过程中的路径规划与引导,不仅关系算法,更取决于所用的路网数据.路网有诸多属性和关系,关系到路径规划速度和引导合理性的最重要特征之一就是经路等级,又称拓扑阶层.本文拟从路径规划的原理出发,引出导航电子地图制作中路网经路等级设计的必要性,继而给出经路等级设计的一般规则以及设计方法,最后通过北京、天津、重庆等多个城市路网经路等级的设计结果,验证了所提出的设计方法的可行性和合理性.  相似文献   
4.
Aims: Depression is the most frequent comorbidity reported among patients with rheumatoid arthritis (RA). Comorbid depression negatively impacts RA patients’ health-related quality-of-life, physical function, mental function, mortality, and experience of pain and symptom severity. The objective of this study was to assess healthcare utilization, expenditures, and work productivity among patients with RA with or without depression.

Materials and methods: Data from adult patients who had at least two visits each related to RA and depression over a 1-year period were extracted from the Truven Health MarketScan research databases. Outcomes comprised healthcare resource utilization, work productivity loss, and direct healthcare costs comparing patients with RA with depression (n?=?3,478) vs patients with RA without depression (n?=?43,222).

Results: Patients with RA and depression had a significantly greater relative risk of hospitalization and number of all-cause and RA-related hospitalizations, utilization of emergency services, days spent in the hospital, physician visits, and RA-related surgeries compared with RA patients without depression. Patients with RA and depression had a higher risk of and experienced more events and days of short-term disability compared with patients without depression. The incremental adjusted annual all-cause and RA-related direct costs were $8,488 (95% CI = $6,793–$10,223) and $578 (95% CI = –$98–$1,243), respectively, when comparing patients with RA and depression vs RA only.

Limitations: The current analysis is subject to the known limitations of retrospective studies based on administrative claims data.

Conclusions: This study suggested increased healthcare utilization, work productivity loss, and economic burden among RA patients due to comorbid depression. These findings emphasize the importance of managing depression and including depression as a factor when devising treatment algorithms for patients with RA.  相似文献   
5.
军民融合产业园区高质量发展对于推进军民深度融合、在全国形成可复制可推广经验具有重要意义。军民融合协同创新通过促进新知识涌现、推进新产业集聚发展,最终汇聚经济发展新动能,驱动园区高质量发展。在提出军民融合协同创新驱动园区高质量发展的机理与组织框架基础上,将发展模式归纳为以分享经济为背景的资源共享模式、以新型研发机构为核心的第三方模式、以产业联盟为核心的产业链拓展模式和以交易平台为核心的“PPP”模式,最后提出相关对策建议。  相似文献   
6.
7.
企业创新是国家经济可持续增长的关键,受到管理层意愿的影响,因而需要对内部经营者的权力进行制衡。以2010-2018年我国A股上市公司为研究样本,实证检验管理层权力制衡强度对企业创新投资的影响,以及不同债务约束情境下高商业信用配置、高负债水平的调节效应,此外,还考察了产权性质的差异化影响。研究表明,管理层权力制衡强度越大,企业创新投资水平越高;高商业信用强化了该促进作用,而高负债水平弱化了该促进作用。进一步研究发现,管理层权力制衡强度与企业创新投资的关系在民企中更显著;国企能够更好地获得和运用商业信用,使其高商业信用对该关系的强化效应更显著;民企具有更强的债务约束,其高负债水平对该关系的弱化效应更明显。  相似文献   
8.
This paper presents an approach to assessing the efficacy of public spending on research and development in state programs. At present, there is a need to develop a unified approach to the analysis and evaluation of the efficacy of such spending from the perspective of participants in state programs (federal executive bodies). The proposed approach does not allow evaluating the efficacy of public spending on the development of research areas assigned to the authors.  相似文献   
9.
Growing urbanisation in South Africa is reflected in burgeoning Working class and informal township settlements on the fringes of its major towns and cities. Paired with this is an increasing reliance on cash as the primary means of economic transaction, which has in turn stimulated the growth of micro-enterprise business activities within the township context. This article discusses the findings of an eight-township small-area census which occurred between 2010 and 2013 in Cape Town, Johannesburg, Ekurhuleni and Durban townships representing 250 000 residents. The researchers were able to establish the scope and scale of informal food and drink retailing in these localities. Of the 10 049 micro-enterprises located in the study, some 3966 (or 39% of the total) trade in food. These include enterprises in primary production, fresh produce retailing, grocery retailing from house and spaza shops, and informal foodservice enterprises. Food is the basis for much township informal business and plays an important role in making food increasingly affordable and locally accessible, and in creating cash employment. The article builds on the knowledge base of the township informal economy role in bolstering food security needs for the marginalised.  相似文献   
10.
At the hydroelectric unit No. 11 of the Nizhnekamsk hydroelectric power plant, the filling wedges of a rotor were investigated by ultrasound in the free st  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