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   970篇
  免费   43篇
  国内免费   10篇
财政金融   25篇
工业经济   84篇
计划管理   398篇
经济学   93篇
综合类   133篇
运输经济   6篇
旅游经济   22篇
贸易经济   157篇
农业经济   43篇
经济概况   62篇
  2024年   1篇
  2023年   8篇
  2022年   6篇
  2021年   6篇
  2020年   13篇
  2019年   10篇
  2018年   8篇
  2017年   14篇
  2016年   15篇
  2015年   35篇
  2014年   59篇
  2013年   65篇
  2012年   71篇
  2011年   110篇
  2010年   106篇
  2009年   53篇
  2008年   57篇
  2007年   66篇
  2006年   71篇
  2005年   57篇
  2004年   54篇
  2003年   22篇
  2002年   30篇
  2001年   33篇
  2000年   17篇
  1999年   7篇
  1998年   9篇
  1997年   5篇
  1996年   2篇
  1995年   1篇
  1994年   3篇
  1993年   2篇
  1992年   1篇
  1990年   1篇
  1989年   2篇
  1988年   1篇
  1986年   1篇
  1985年   1篇
排序方式: 共有1023条查询结果,搜索用时 15 毫秒
1.
This paper explores alternative ways of evaluating and ultimately hiring a generalist consultancy for short- and medium-term projects, and how this is shaped by the size of the clients’ company. What buying factors do managers of small and large firms have in mind when hiring consultants for their projects?Instead of employing surveys incorporating predefined buying factors based on what the researchers think would be important, a cognitive mapping methodology - the repertory grid technique - is applied to investigate the underlying phenomena. Using the repertory grid technique to draw mental models is a novel research technique within the supply management field. Recent behavioral supply chain management research found the behavior of managers to be critically influenced by mental models: the lenses through which managers perceive, simplify and interpret the world.Results show differences between the buying factors used in small- and large-scale companies: managers of large companies are more ‘reputation and outcome-oriented’ and managers of small businesses are more concerned with ‘how the services are rendered’. However, both constituents stressed the importance of expertise, quality and the relationship between the client and the management consultancy, although the character of such a relationship differed between small- and large-scale firms. Results also point out criteria that managers of small and large companies employ to discriminate between good and poor performing consultancies and to judge service delivery. The practical implications for both companies hiring consultancies and the consultancy companies are discussed. For consultancies, our findings can help tailoring their efforts to a differing clientele when marketing and selling their services. For companies hiring consultancies, fixating too much on particular buying factors may lead to biased decisions.  相似文献   
2.
ABSTRACT

The purpose of the current study is to investigate how attendees’ approach behavior is influenced by exhibitors’ dress conformity. A 2 × 2 between-subjects quasi-experimental design was utilized for this study. Our results showed that conforming dress for exhibitors can lead to a higher level of approach behavior of trade show attendees as compared with nonconforming dress, and the effect of exhibitors’ dress styles on approach behavior is moderated by attendees’ self-construal. Findings of this study provide significant insights for trade show exhibitors and attendees.  相似文献   
3.
基于冠层光谱和BP神经网络的水稻叶片氮素浓度估算模型   总被引:4,自引:0,他引:4  
[目的]快速、准确地诊断水稻叶片氮素营养状况,为水稻氮肥精准管理提供依据。[方法]以江西省农科院8种不同施肥处理的晚稻为研究对象,于主要生育期同步测定了水稻冠层光谱反射率及叶片全氮浓度(Leaf Nitrogen Concentration,LNC),系统分析了原始光谱反射率、一阶微分光谱、"三边"参数以及由350~1 350nm两两波段组合的差值(SD (Rλ1,Rλ2))、比值(SR (Rλ1,Rλ2))及归一化(ND(Rλ1,Rλ2))光谱指数与水稻LNC的相关关系,筛选出敏感参数,并以之为自变量构建了水稻LNC的传统预测模型,另外构建不同指标个数的多元线性与BP神经网络模型,并对模型进行验证。[结果](1)水稻LNC与一阶微分光谱在751nm处的相关性最高(r=0. 822);(2)"三边"参数中的红边面积SDr与LNC的相关性较高(r=0. 687);(3) 750nm附近的红边波段与近红外波段差值组合、550nm附近的绿光波段与近红外波段的比值及归一化差值组合与水稻LNC的相关性较高,以SD (R752,R751)、SR (R534,R1 350)和ND (R534,R1 349)表现最好,相关系数分别为0. 827、-0. 790和0. 788;(4)传统回归模型中以SD(R752,R751)构建的一元线性模型最佳(RC2=0. 665、RV2=0. 750、RMSEV=0. 4%、RPD=2. 034);(5)利用5个指标((R'751、SDr、SD (R752,R751)、SR (R534,R1 350)、ND (R534,R1 349))经逐步回归筛选出的2个指标SD ((R752,R751)和SR (R534,R1 350))构建预测水稻氮素的BP神经网络模型,预测效果最佳,其验证参数值分别为R2=0. 859、RMSEV=0. 302%和RPD=2. 669。[结论]基于单指标构建的传统线性模型计算过程简单但精度略低,而基于2个指标(SD (R752,R751)、SR (R534,R1 350))构建的BP神经网络模型预测精度高于该2指标构建的多元线性模型,表明在指标适合的情况下,BP神经网络对氮素具有较好的预测能力,是一种快速准确估算水稻叶片全氮浓度的方法。  相似文献   
4.
With the expansion of urbanization caused by the growth of population and industrial activities, the urban/city and suburban areas are facing a variety of environmental threats. Although more research and urban policy has advocated and practiced the development of green infrastructure (GI) to support urban sustainable environment, the evaluation framework for the development of GI for promoting environmental sustainability is still insufficient. Moreover, the Analytic Hierarchy Process (AHP) commonly applied in published literature, makes an unrealistic assumption of independent relationships among dimensions/criteria in decision making for satisfying the real-world problem. Therefore, the purpose of this study is to construct the evaluation framework, including four dimensions and related ten criteria, using a new hybrid-modified multiple attribute decision-making (MADM) model for developing and improving the GI for promoting environmental sustainability. This MADM model is combined with three different methodologies of MADM, including the Decision-Making Trial and Evaluation Laboratory (DEMATEL) for constructing the influential network relation map (INRM) to explore the complex influential inter-relationships and DEMATEL based on Analytic Network Process (DANP) for determining the influential weights with the VIse Kriterijumska Optimizacija I Kompromisno Resenje (VIKOR) for evaluating and presenting improvement strategies for six different GIs. The empirical study indicates that DEMATEL and DANP Results suggest that decision-makers should pay more attention to the improvement of Design (D4) and Materials (D2) in terms of dimensions when utilizing the GI to promote environmental sustainability. Because these dimensions are enhanced, Species (D1) and Energy (D3) will be improved in synchronization. From the perspective of criteria, five are key core criteria and need to be focused on first: increasing the green coverage rate (B9), utilizing sustainable materials (B4), using ecological engineering (B8), shaping species biodiversity (B1), and reducing energy consumption (B5). Modified VIKOR reveals that “grass swales” are a comparatively better choice among six GIs for promoting environmental sustainability toward achieving the aspiration level. Therefore, this MADM model is beneficial to provide a more convincing assessment framework and improvement strategies for the development of GI for promoting environmental sustainability. As a result, these modified MADM models can be shown more conveniently and reasonably than traditional methods such as traditional AHP or ANP method.  相似文献   
5.
This research is about a Delphi study that was conducted in the context of the development of a competence model for sustainable purchasing and supply management (SPSM). Based on the findings of a systematic literature review (SLR), it addresses the research gap in this area with the aim to foster the integration of sustainability in purchasing and supply management (PSM) in higher education and in professional training approaches for PSM professionals. The qualitative study was conducted with 16 Delphi experts in the field of PSM and sustainability, applying the critical incident technique (CIT). Together with the findings of the SLR, it led to a specific set of SPSM competences. The theoretical background is based on PSM research, educational sciences and organizational psychology.  相似文献   
6.
针对传统阀门质量检验统计分析以人工统计为主、耗时长、效率低、时效性差、结果不准确等问题,通过开发智能质量检验统计分析系统,自动采集压力试验数据,自动生成检验记录、检验报告以及各类报表,还可以根据制造厂商、阀门类型、缺陷种类等自动生成柱状图、饼状图等质量分析图表,降低了人工录入数据的差错率,检索统计准确迅速,提高了检验效率和检验质量,为产品质量管理提供了快捷、高效的决策数据。  相似文献   
7.
The Canada Foundation for Innovation (CFI) and the Canadian Institutes of Health Research (CIHR) allied to analyze the impact of their investments in medical imaging research. The CFI funds capital and operating programs for research infrastructure, and CIHR's mandate concentrates its funding on research activity. It happens that CIHR-funded research consumes CFI-funded infrastructure as an input in the innovation process. Apart from a few partnered programs, by design there is no coordination between CFI and CIHR funding decisions. Together, these agencies invested $916 million over a 14-year-period. In this paper, we evaluate the economic and health benefits from advancements in one funded area, namely computed tomography perfusion (CTP). CTP is an imaging technique that uses computed tomography to measure blood flow in organs and tissues. It is mostly used to assess acute ischemic stroke. The net social benefits attributable to these investments are substantially positive: the benefit-to-cost ratio is estimated to be between 6.66-to-1 and 9.99-to-1. We review how public investments from multiple funders comingle in the innovation process to deliver social value and improved health outcomes.  相似文献   
8.
水下激光成像在海洋目标的观测和识别方面具有重要的作用,相比传统的声纳的手段,激光成像在图像的直观性、分辨率和可视性方面具有显著的优势,文中介绍了距离选通技术的工作原理,并分析了水下激光成像设备关键器件的选择和国内外发展现状,对促进我国水下激光光电成像技术的发展具有重要的意义。  相似文献   
9.
胡秀玲 《价值工程》2014,(26):36-37
红外诊断技术是一种新型诊断技术,为变电设备的热诊断提供了很好的诊断方式,该种诊断方式有着不解体、直观性、快速性、准确性的特征,也适宜用在大面积检测中,同时,该种诊断技术也能够与其他检测方式联合使用,定位故障的具体位置,这就可以有效提升检修的便利性。但是,影响红外线热成像诊断技术准确率的因素是多种多样的,在进行诊断时,必须要合理地控制其测量环境与测量方式。本文主要分析影响红外线热成像诊断技术准确性的因素,并提出相关的解决措施。  相似文献   
10.
刘洪清 《价值工程》2014,(34):145-148
锦屏二级水电站上游调压室顶拱为渐变城门洞型,其最大开挖尺寸长宽高分别为49.5m×22.532~30m×15.25m;在整个调压室顶拱开挖支护过程中,为确保顶拱施工质量、安全及进度,施工项目部报送了专项施工技术方案,监理工程师对该方案进行了认真细致地审查,达到了预期的效果、并取得了良好的成效,在大跨度调压室顶拱开挖支护施工技术和工程监理方面积累了一些成功的经验。  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