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   797篇
  免费   38篇
  国内免费   1篇
财政金融   22篇
工业经济   36篇
计划管理   328篇
经济学   220篇
综合类   50篇
运输经济   3篇
旅游经济   7篇
贸易经济   61篇
农业经济   74篇
经济概况   35篇
  2024年   3篇
  2023年   13篇
  2022年   13篇
  2021年   25篇
  2020年   42篇
  2019年   23篇
  2018年   22篇
  2017年   39篇
  2016年   25篇
  2015年   36篇
  2014年   63篇
  2013年   145篇
  2012年   60篇
  2011年   97篇
  2010年   72篇
  2009年   18篇
  2008年   47篇
  2007年   23篇
  2006年   16篇
  2005年   11篇
  2004年   5篇
  2003年   9篇
  2002年   6篇
  2001年   8篇
  2000年   4篇
  1999年   7篇
  1997年   1篇
  1996年   1篇
  1993年   1篇
  1990年   1篇
排序方式: 共有836条查询结果,搜索用时 31 毫秒
1.
Air travelers can carry an infectious disease's pathogenic microorganism in their bodies and spread the disease from one country to another in a few days. To delay the spread, health screening stations may be set up at airport terminals to screen travelers. This research tested three different health screening strategies, each with a different combination of screening stations at trip origins, destinations and connecting airports. Discrete event simulations were performed, based on the 2014 to 2016 Ebola virus epidemic, with special focus on travelers from the West African countries traveling to the United States, including travelers who transferred flights at airports in European Union member states. The effectiveness of the screening strategies was analyzed in terms of correct detection, missed detection and false alarm rate. The results showed that exit screening at trip origins brought big improvements in the performance measurements compared to no screening. However, additional screening at the destinations and connecting airports contributed marginal benefits.  相似文献   
2.
This study examines the sources of labor productivity growth dynamics in Japan (1970–2010) and investigates the extent to which Japanese economic performance has been affected by Baumol's growth disease (BGD). We find that BGD silently undermines Japanese economic growth. However, the magnitude is miniscule, and consequently the aggregate labor productivity growth rate has not been decreasing monotonically. We also explore how BGD is arising and why it is small in the Japanese economy. BGD is weak because (1) the positive Baumol growth effect is also working in certain services sectors and (2) BGD is not a durable phenomenon: even if a sector begins to suffer from BGD, it is likely to recover quickly.  相似文献   
3.
从心身医学的角度,阐述冠状动脉硬化性心脏病的病因学,心理生物学机制及防治;对现代社区医疗卫生工作中的老年疾病的康复保健具有一定的指导意义。  相似文献   
4.
河南省生鲜农产品在物流环节损失巨大,发展冷键物流是实现“产后减损“、提高农产品质量最有效的途径,对促进农民增收意义重大,因此大力发展冷链物流势在必行.文中首先分析了河南省生鲜农产品冷链物流的发展现状,然后结合河南省实际情况,提出河南省发辰生鲜农产品冷链物流的六项对策.研究成果旨在为河南省以及与河南省省情相似的雀份发展生鲜农产品冷链物流提供参考.  相似文献   
5.
电子商务环境下的冷链物流研究   总被引:2,自引:3,他引:2  
当今信息时代,人们将先进的信息和网络技术应用到物流管理中,极大地促进物流事业的发展,第三方物流事业也应运而生且发展前景广阔。它的优势就在于降低了生产成本。提高了经营效率,加强了竞争力,提升了企业彤象。作为现代物流的一个组成部分,冷链物流也伴随着社会的进步.技术的更新和管理思想的发展而不断地发展。在电子商务环境下如何实施冷链物流是冷链行业面临的重要课题。本文通过对一个成功的第三方冷链物流案例的分析,结合我国国情,提出相应实施策略。  相似文献   
6.
现代果品物流发展的冷藏链模式研究   总被引:2,自引:0,他引:2  
研究了当前我国现代果品物流发展中冷藏链模式所必须具备的五个条件和软件技术以及硬件基础设施建设。基于此,本文设计了我国果品快速供销反应冷藏链与冷藏链流通模式。  相似文献   
7.
Abstract

Aims

To characterize a US population of patients with irritable bowel syndrome with constipation (IBS-C) or chronic idiopathic constipation (CIC) using CONTOR, a real-world longitudinal research platform that deterministically linked administrative claims data with patient-reported outcomes data among patients with these conditions.  相似文献   
8.
用神经网络对开式冷挤压极限变形程度的预测   总被引:2,自引:0,他引:2  
给出了基于 BP网络的极限变形程度预测的分析方法 ,得到了开式冷挤压εmax神经网络计算结果 ,与实验结果比较 ,其精度较高 ,证明了神经网络模型在开式冷挤压工艺中应用的可行性。  相似文献   
9.
The disability-adjusted life year (DALY) is a summary health measure that combines mortality and morbidity into a single measure as a way to estimate global disease burden and the effectiveness of health interventions. We review the methodological progression of the DALY, focusing on how the use of life expectancy estimates, disability weights, age weighting, and discounting has evolved since the first DALY reports were published in 1993. These changes have generally improved the metric but have made it difficult for researchers to interpret, compare, and conduct DALY studies.  相似文献   
10.
There is growing concern that trade, by connecting geographically isolated regions, unintentionally facilitates the spread of invasive pathogens and pests – forms of biological pollution that pose significant risks to ecosystem and human health. We use a bioeconomic framework to examine whether trade always increases private risks, focusing specifically on pathogen risks from live animal trade. When the pathogens have already established and traders bear some private risk, we find two results that run counter to the conventional wisdom on trade. First, uncertainty about the disease status of individual animals held in inventory may increase the incentives to trade relative to the disease-free case. Second, trade may facilitate reduced long-run disease prevalence among buyers. These results arise because disease risks are endogenous due to dynamic feedback processes involving valuable inventories, and markets facilitate the management of private risks that producers face with or without trade.  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