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   4287篇
  免费   149篇
  国内免费   34篇
财政金融   118篇
工业经济   564篇
计划管理   1863篇
经济学   338篇
综合类   277篇
运输经济   122篇
旅游经济   52篇
贸易经济   531篇
农业经济   295篇
经济概况   310篇
  2024年   7篇
  2023年   39篇
  2022年   83篇
  2021年   122篇
  2020年   117篇
  2019年   65篇
  2018年   72篇
  2017年   95篇
  2016年   150篇
  2015年   135篇
  2014年   429篇
  2013年   488篇
  2012年   473篇
  2011年   533篇
  2010年   442篇
  2009年   306篇
  2008年   204篇
  2007年   191篇
  2006年   157篇
  2005年   120篇
  2004年   77篇
  2003年   46篇
  2002年   34篇
  2001年   26篇
  2000年   13篇
  1999年   12篇
  1998年   6篇
  1997年   9篇
  1996年   5篇
  1995年   2篇
  1994年   3篇
  1993年   3篇
  1992年   2篇
  1990年   1篇
  1988年   1篇
  1984年   1篇
  1981年   1篇
排序方式: 共有4470条查询结果,搜索用时 46 毫秒
1.
Facing transparency requirement of ad generation process, digital marketers need to design proper transparency messages to preempt consumer backlash. Based on crowd psychology literature and the regulatory focus theory, we proposed and tested the crowd safety effect of the collective-based (vs. individual-based) ad transparency strategy with two experimental studies in the context of online hotel booking. Results of two studies consistently demonstrate the crowd safety effect of the collective-based transparency on enhancing hotel booking intention and ad click-through willingness. Furthermore, we found that consumers’ trust toward the ad, rather than privacy concern, mediates this positive effect. These findings help us better understand how social dimensions in ad transparency messages shape consumer responses, as well as the role of consumer trust in promoting targeted ad effectiveness through promotion focused behaviors.  相似文献   
2.
为探究生产安全事故的演化规律,基于长沙市2019—2020年生产安全事故的数据,从事故发生时间、发生区域、行业和领域分布、事故等级等方面进行分析。研究表明:2019—2020年事故数量和死亡人数呈下降趋势,1月、8月、10月事故数量和死亡人数较多,2月事故数量和死亡人数少;非主城区的事故数量和死亡人数高于主城区,事故数量和死亡人数在空间上的分布比较均衡;道路运输和工矿商贸行业在全市生产安全事故中占绝大多数;工矿商贸行业中,建筑施工行业的事故数量和死亡人数最多;一般事故所产生的事故数量和死亡人数最多,重大事故的事故死亡率最高。  相似文献   
3.
牛肉是西餐主要的食材之一。本文通过对牛肉的初加工技术进行分析,探究对西餐牛肉类进行食品安全控制的措施,以提高牛肉类产品的整体质量,使西餐牛肉类产品能够达到我国食品安全的标准。  相似文献   
4.
为了提高双离合变速器在车辆上的换挡品质,提升电气化换挡执行机构的工作效率,给出执行机构性能与换挡品质评价准则;通过两种不同双离合变速器电控电动执行机构的工作原理与性能分析,基于MATLAB数值仿真方法优化出最高效率进行试验.基于车辆6个维度的换挡工况对二者所搭载的变速器分别进行试验与CAN线数据采集,对比研究两种机构优缺点,通过雷达图的方式进行优劣说明.结果表明,两种执行机构传动效率可达70%且换挡品质相当.可见Tip in tip out工况对二者要求最为严格.  相似文献   
5.
我们已经进入了一个全新的大数据信息化时代,充满了更多的机遇与挑战。大数据及数字经济的出现极大程度地改变了传统技术及工作思维的方式。数字经济是继工业和农业之后的又一大经济形态,为社会的经济增长提供了新的动力。通过分析电网行业传统的科学技术及作业方式,论文简要阐述了基于大数据信息化发展下电网的影响,并认为信息化技术的发展对于数字经济有着至关重要的影响及重要性。最后论文讨论了数字经济发展存在的问题及方向。  相似文献   
6.
Abstract

Not long after the beginnings of motorization in the early 1900s, deaths and injuries from motor vehicle crashes became a problem in a number of high-income-countries (HIC)s, especially the United States. With the biggest problem the US led early efforts to address this issue, and for six decades these efforts were based on folklore (ie a body of widely held but false or unsubstantiated beliefs). They were not evaluated, but clearly were unsuccessful as crash deaths and injuries continued to rise. It was not until the 1970s that a broader range of countermeasures began to be adopted and was scientifically evaluated, and as a result, crash deaths and injuries declined. This history has important lessons today for many low-and-middle-income countries that have growing numbers of motor vehicle crash deaths and injuries, many of which are pedestrians and motorcyclists. This is because there continue to be advocates for many of the failed approaches (especially educational) that dominated the early efforts in HICs.  相似文献   
7.
While the transmission of virus SARS-CoV-2 via food is rare, some Chinese food retailers are considering a Covid-19-tested food label. However, how consumers may support such a label is unknown. We quantify Chinese consumers’ willingness to pay (WTP) for food carrying a Covid-19-tested label using an online choice experiment. We find that the WTPs for such a label are always positive for all food products considered. The amount of WTP depends on the entities authenticating the labels, country of origin of the food, and consumers’ socio-demographic status. Contrary to expectation, the knowledge on Covid-19 does not affect consumer preferences for the Covid-19-tested food labels. Our benefit and cost analysis suggests a possible large benefit of creating and administering a Covid-19-tested food label. This study provides insights for policymakers, global food manufacturers, and retailers to create marketing strategies to alleviate consumer food safety concerns associated with Covid-19.  相似文献   
8.
The present study investigates a potential preventive factor in relation to workplace bullying. Specifically, we examine how climate for conflict management (CCM) may be related to less bullying, increased work engagement, as well as whether CCM is a moderator in the bullying engagement relationship. The study was based on a cross-sectional survey among employees in a transport company (N = 312). Hypotheses were tested simultaneously in a moderated mediation analysis which showed that bullying and job engagement were related (H1), CCM was related to less reports of bullying (H2), CCM was related to work engagement (H3) and that CCM was indirectly related to job engagement through bullying (H4), but only when CCM was weak (H5). That is, CCM moderated the relationship between bullying and work engagement in that this relationship only existed when CCM was low. The present study contributes to theory within this research field by showing that organizational measures may not only prevent bullying, but may also affect how employees react when subjected to bullying. Furthermore, the effect of climate in relation to bullying may be down to the narrow bandwidth facet of CCM. The study informs employers how they may act to prevent bullying while also reducing the potential negative outcomes of those cases of bullying that inevitably will show up from time to time.  相似文献   
9.
针对双站定位涉及的跳频信号多普勒频差估计问题,提出了归一化的频差最大似然估计算法,利用两个定位站接收到的跳频脉冲串信号,构建一个关于基准跳频频率多普勒频差的似然函数,通过网格搜索得到使似然函数最大的多普勒频差估计,既解决了跳频信号在不同跳频频率上多普勒频差不一致的问题,又充分利用在不同频率的脉冲串信号提高了多普勒频差估计精度。通过仿真对算法的性能进行了评估,结果表明,与基于子空间的算法比较,在脉冲数达到240个时,所提算法执行效率提升30%以上。  相似文献   
10.
在复杂电磁环境下,由于民航地空通信大频偏的要求,滤波器无法滤除波道内的干扰。针对此问题,提出了一种自适应抗干扰系统设计方法。对于落在波道内且与地空通信信号有效频带不重叠的干扰,首先对通信信号进行载波频率估计,然后使用自适应滤波方法进行干扰抑制;对于落在波道内且与地空通信信号有效频带重叠的恒包络干扰,首先重构载波信号,消除对恒包络信号估计的影响,然后根据恒包络信号的特性重构干扰信号并进行干扰分离。实验结果表明,该系统设计方法在不改变民航地空通信架构的前提下,抗有效频带外干扰的能力最大可以提升23.8 dB,抗恒包络干扰的能力最大可以提升39.4 dB,从而可以大幅提高航空飞行安全水平。  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