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   13884篇
  免费   362篇
  国内免费   65篇
财政金融   1447篇
工业经济   904篇
计划管理   2950篇
经济学   2436篇
综合类   1558篇
运输经济   130篇
旅游经济   99篇
贸易经济   1671篇
农业经济   922篇
经济概况   2160篇
邮电经济   34篇
  2024年   14篇
  2023年   99篇
  2022年   247篇
  2021年   381篇
  2020年   309篇
  2019年   200篇
  2018年   202篇
  2017年   328篇
  2016年   230篇
  2015年   376篇
  2014年   538篇
  2013年   760篇
  2012年   1167篇
  2011年   1656篇
  2010年   1504篇
  2009年   1000篇
  2008年   1126篇
  2007年   1039篇
  2006年   1070篇
  2005年   886篇
  2004年   269篇
  2003年   224篇
  2002年   214篇
  2001年   179篇
  2000年   104篇
  1999年   57篇
  1998年   42篇
  1997年   21篇
  1996年   17篇
  1995年   10篇
  1994年   5篇
  1993年   10篇
  1992年   5篇
  1991年   6篇
  1990年   1篇
  1989年   3篇
  1988年   3篇
  1987年   2篇
  1984年   5篇
  1979年   1篇
  1900年   1篇
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
11.
ABSTRACT

The escalating U.S.–China trade conflicts have increasingly shadowed the outlook of the world economy. The Trump administration aims to achieve its strategic goals including reducing current account deficits, promoting the U.S. manufacturing sector, and curbing Chinese high-tech industries by waging the trade war against China. This paper argues that the current account deficits and the declining manufacturing sector in the U.S. are mainly driven by its internal structural factors, such as low saving rates, high labor costs, and rising service sector, rather than by the import competition from China. Moreover, the trade war further deteriorates the U.S. current account deficits and erode its comparative advantage, and it forces China to invest more in technological innovation and human capital, and thus promote its progress in high-tech industries. Thus, the U.S. will not be able to achieve its strategical goals and eventually lose the trade war.  相似文献   
12.
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   
13.
Unlike most of the literature that examines the relationship between corporate philanthropy and financial performance, this study investigates the mechanisms through which corporate socially responsible behaviors produce financial outcomes. We propose that corporate philanthropy improves corporate competitiveness by eliciting positive responses from stakeholders, who assess a firm’s philanthropic contribution in relation to its rivals to determine what level of support they wish to provide to the firm. We predict that a firm’s philanthropy relative to its rivals has a positive effect on its product market competitiveness, and that this positive effect is moderated by three conditions that influence stakeholder response: stakeholder attention to philanthropy, its perceived legitimacy, and expectations of corporate giving. Our predictions are generally supported by our analyses. Overall, this paper shows that strategic philanthropy has a quantitative dimension, and firms obtain the market competitiveness associated with corporate philanthropy by integrating their rivals’ positions into their decision making.  相似文献   
14.
The Journal of Real Estate Finance and Economics - In the existing housing literature, there has been no academic consensus on how to combine the spatial dependence and the temporal dependence...  相似文献   
15.
The boundary conditions of supply chain integration (SCI) have been widely studied in order to find out when SCI is applicable and effective. However, prior studies have mainly focused on external contextual factors, such as supply complexity, environmental uncertainty and country-level infrastructure. This study contributes to the SCI literature by examining the contingency effects of internal production systems on the relationship between supplier integration, customer integration and operational performance. Based on organizational information processing theory, we provide evidence to show that the impact of supplier and customer integration on operational performance varies across production systems, such as one-of-a-kind production, batch production and mass production systems. The empirical results also reveal how supplier and customer integration can be matched with different configurations of production systems in order to achieve the desired quality, flexibility, delivery or cost performance.  相似文献   
16.
中国的家族企业形成规模的目前还为数不多,而小型企业的数量却与日俱增。美国家族企业一直是美国经济中至关重要的一股力量,1969-1976年间雇员不足20人的企业创造了美国66%的就业机会,近20年来小型企业成为美国劳动力市场的一个重要组成部分。  相似文献   
17.
铬渣的无害化处理和综合利用   总被引:13,自引:2,他引:11  
铬渣产量大、毒性剧烈,是严重污染生态环境和危害人类健康的危险废物.本文介绍了铬渣各种无害化处理方法的解毒机理、工艺过程和应用实践,阐述了对铬渣进行综合利用的途径,并就铬渣的防治措施提出了建议.  相似文献   
18.
This article focuses on the housing issues of rural migrants arising from urbanization, with particular reference to chengzhongcun, a topic with considerable impact on policymaking. An attempt is made to understand the underlying rationale of self‐help in housing and the important role of chengzhongcun in sheltering rural migrants in the context of China's rural‐urban dichotomy. As demonstrated in this study, chengzhongcun accommodate, with little in the way of government resources and assistance, millions of rural migrants because of their social accessibility and affordability. While not denying their social problems, we argue that chengzhongcun in fact act as an innovative and positive agent to promote urbanization in present day China by housing massive numbers of rural migrants and assimilating them into cities. Current government policies towards chengzhongcun have generated a wide range of interest conflicts and confrontations. The consequences of such conflicts show that the government policies were problematic and unworkable, as they violated basic market principles as well as citizen rights. Policy strategy towards the redevelopment of chengzhongcun must acknowledge their credibility in the Chinese road to urbanization and requires more thoughtful and prudent consideration of migrants' demands for affordable housing.  相似文献   
19.
赵达 《上海国资》2004,(5):23-24
6年来,国企经营者年薪制改革两次因故受阻,这其中存在一些亟待解决的深层次问题。要理性认识年薪制改革当前的目标和作用,认识这一改革的艰巨性和长期性,突出重点,化解主要矛盾,推进年薪制改革顺利进行。  相似文献   
20.
生命周期评价方法及其应用   总被引:6,自引:0,他引:6  
介绍了生命周期评价的目的、意义和基本方法,并运用该方法对燃煤发电、废纸造纸、废旧塑料气化发电等几种不同工业过程的环境影响进行了分析。  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