全文获取类型
收费全文 | 9519篇 |
免费 | 416篇 |
国内免费 | 195篇 |
专业分类
财政金融 | 879篇 |
工业经济 | 515篇 |
计划管理 | 2387篇 |
经济学 | 1491篇 |
综合类 | 1384篇 |
运输经济 | 65篇 |
旅游经济 | 288篇 |
贸易经济 | 1538篇 |
农业经济 | 646篇 |
经济概况 | 937篇 |
出版年
2024年 | 11篇 |
2023年 | 125篇 |
2022年 | 174篇 |
2021年 | 211篇 |
2020年 | 329篇 |
2019年 | 234篇 |
2018年 | 206篇 |
2017年 | 262篇 |
2016年 | 265篇 |
2015年 | 279篇 |
2014年 | 585篇 |
2013年 | 809篇 |
2012年 | 771篇 |
2011年 | 871篇 |
2010年 | 653篇 |
2009年 | 616篇 |
2008年 | 766篇 |
2007年 | 710篇 |
2006年 | 611篇 |
2005年 | 515篇 |
2004年 | 371篇 |
2003年 | 258篇 |
2002年 | 157篇 |
2001年 | 111篇 |
2000年 | 73篇 |
1999年 | 44篇 |
1998年 | 24篇 |
1997年 | 24篇 |
1996年 | 18篇 |
1995年 | 8篇 |
1994年 | 4篇 |
1993年 | 6篇 |
1992年 | 10篇 |
1991年 | 4篇 |
1990年 | 3篇 |
1989年 | 2篇 |
1988年 | 2篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1983年 | 2篇 |
1982年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
81.
Agricultural applications of nanotechnology are at a relatively early stage and little is known about consumer responses to the technology. Canadian consumer responses to food nanotechnology are examined through the lens of the Food Value Scale. Data from a survey of Canadian consumers are used to evaluate the relative importance of eleven food values to food purchase decisions. We find that taste, safety, nutrition, and price are among the most important food values to Canadians, however, consumers exhibit considerable heterogeneity with respect to the priority placed on these values. A discrete choice experiment (DCE) explores the effect of food values on choice behavior. The DCE is positioned as a sliced apple product with non-browning and antioxidant-enhanced features introduced through the use of nanocoating or a conventional coating method. Random parameters logit (RPL) and latent class models (LCM) confirm the existence of significant preference heterogeneity. The LCM identifies three classes of consumers: “supporters,” “doubters,” and “opponents” who differ in their reaction to nanotechnology and in the relative importance placed on food values such as naturalness, novelty, and convenience. The analysis shows that food values provide additional insights into consumers’ food choices and their attitudes toward novel food technologies. 相似文献
82.
城市近郊区农户土地投入行为绩效评价及障碍因子诊断 ——耕地多功能价值视角下的多群组对比分析 总被引:1,自引:0,他引:1
研究目的:基于耕地多功能价值的视角研究农户土地投入行为绩效并诊断其障碍因子,以探索当前形势下城市近郊区农户"既不愿意种地,又不愿意将土地流转"的深层原因.研究方法:在构建农户土地投入行为绩效分析框架的基础上,通过农村入户调查获得样本数据,采用熵权TOPSIS法和障碍度模型,对不同性别和年龄阶段农户的土地投入行为展开绩效分析.研究结果:总体上,城市近郊区农户的土地投入行为绩效水平为"良好";多群组对比分析显示,男性绩效水平高于女性,青壮年绩效水平高于老年;补贴标准偏低和职业认同感差是制约土地投入行为绩效的主要障碍因子,而满足就业和养老需求依然是耕地资源的核心价值功能.研究结论:耕地在农户认知层面发挥着"弱保障"功能,"存而不用"的保守心态在事实上导致家庭承包地处于闲置、撂荒状态,这便是当前形势下城市近郊区耕地资源低效利用的底层逻辑. 相似文献
83.
This study examines the sources of negative momentum profits by combining investor attention and the properties of common and firm-specific factors. We choose the Korean stock market as a good case to characterize the negative momentum profits identified in Asia. In both portfolio and stock analyses, a method is devised to generate return data involving the property of each common and firm-specific factor within stock groups by investor attention. This study found significant negative momentum profits within the stock group with high investor attention. This momentum effect is highly dependent on the reversed performance of the past loser portfolio, not the continued performance of the past winner portfolio, and this reversal is strongly attributable to the properties of firm-specific factors, and not those of common factors. These results are robustly consistent regardless of changes in empirical design and the consideration of influence factors, market dynamics, and other stock markets. 相似文献
84.
85.
世界遗产标准vii是UNESCO用以评价遗产地审美
价值的重要准则,由标准iii演化而来,从文化与自然美的混
合评价转向了仅对自然美学特征评价。选取以标准vii列入世
界遗产名录的145处项目(1978—2017年),通过扎根理论
及分析,总结其运用特征、演化趋势和动因考辨。研究发现:
1)地区层面,不同地区运用标准vii所关注的审美价值具有差
异,如非洲关注色彩美学,欧洲和北美强调风景特质组合,亚
太地区重视强烈的自然文化关联、动态变化和组合关系,南美
和加勒比地区注重审美体验;2)词频运用层面,标准vii在各
地区的词频运用差异显著,各地区使用词频最高的为关于美的
“形容词”,除欧洲之外,其余地区代表“之最”特点的词频
次之;3)评价要点层面,欧洲和北美的风景特质评价具有很
强的特点与范式。最后解析了标准vii运用趋势与18世纪以来
的美学思想演变的内在联系;以期为标准vii的全球普世价值
与地区价值认知以及标准vii后续研究提供依据。 相似文献
86.
87.
The present study examines the relationship between corporate social responsibility (CSR) and firm value, and the effects of corporate governance code revisions on the relationship. We examine this relationship for: (i) a high‐income country, Japan; (ii) middle‐income countries China, Malaysia and Thailand; and (iii) low‐income countries India and Indonesia. We use the Heckman two‐stage sample selection bias approach for the empirical analysis. We find that Japanese stakeholder CSR and environmental CSR have a smaller positive effect on firm value compared to the middle‐income countries, but we do not find any statistically significant association for the low‐income countries. In addition, we find that only Japanese corporate governance code revisions significantly contribute to the positive relationship between CSR and firm value, which concurs with the new recommendations documented in the revised codes of corporate governance. The present study reveals that foreign major shareholders matter to the value creation of CSR in Japan and the middle‐income countries of China, Malaysia and Thailand. 相似文献
88.
This study investigates the level of risk due to fat tails of the return distribution and the changes of tail fatness (TF) through portfolio diversification. TF is not eliminated through portfolio diversification, and, interestingly, the positive tail has declining fatness until a certain level is reached, while the negative tail has rising fatness. This indicates that fat tails are highly relevant to common factors on systematic risk and that the relevance of common factors is higher for the negative tail compared to the positive tail. In the portfolio diversification effect, the declining fatness of the positive tail further reduces risk, but the rising fatness of the negative tail does not contribute to this effect. The asymmetry between the fatness of the positive and negative tails in the return distribution corresponds to the asymmetry of the trade-off relationship between loss avoidance and profit sacrifice that is expected as a consequence of portfolio diversification. Investors use portfolio diversification to reduce their risk of suffering high losses, but following this strategy means sacrificing high-profit potential. Our study provides empirical confirmation for the practical limitation of portfolio diversification and explains why investors with diversified portfolios suffer high losses from market crashes. An examination of the Northeast Asian stock markets of China, Japan, Korea, and Taiwan show identical results. 相似文献
89.
人工智能技术的快速发展正催生第四次工业革命,可能引发全球价值链深度重构和世界经贸格局重大变革。世界主要经济强国将发展人工智能技术作为争夺新一轮产业竞争优势的重要战略抓手。本文基于全球价值链视角研究人工智能技术变革对国际贸易的影响,我们发现人工智能技术变革可能推动国际贸易规模扩大,提升服务贸易份额,并促进国际贸易交易模式平台化、小宗化,可为中小企业创造更多参与国际贸易的机会。然而,人工智能技术变革也可能通过降低企业劳动力需求从而对我国等发展中国家的出口拉动型增长模式造成严重的潜在威胁。为应对人工智能技术变革,我国应部署并强化对人工智能产业发展的政策支持,加快培育制造业国际竞争新优势,大力推动先进制造业与现代生产性服务业深度融合发展,全面促进"中国制造"攀升全球价值链中高端。 相似文献
90.
为解决位置指纹定位在离线阶段构建位置指纹库时耗费的人力和时间成本较大,构建指纹库效率低和利用空间插值法构建的指纹库精度不高的问题,提出了一种融合反距离加权和矩阵填充的位置指纹库构建算法。该算法仅需人工采集定位区域内少量参考点的接收信号强度值用作信标点指纹信息,结合反距离加权算法特性计算出次信标点指纹信息,根据位置指纹库数据矩阵的低秩性,应用奇异值阈值矩阵填充算法构建出位置指纹数据库。仿真实验结果表明,所提算法有效降低了矩阵填充算法构建位置指纹库所需的人工和时间成本,构建出的位置指纹库定位性能优于反距离加权和克里金空间插值法,接近传统人工采集法,显著地提高了位置指纹库的构建效率。 相似文献