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   18902篇
  免费   502篇
  国内免费   1篇
财政金融   3805篇
工业经济   1296篇
计划管理   3194篇
经济学   4187篇
综合类   207篇
运输经济   85篇
旅游经济   261篇
贸易经济   3374篇
农业经济   850篇
经济概况   1878篇
邮电经济   268篇
  2021年   123篇
  2020年   225篇
  2019年   289篇
  2018年   420篇
  2017年   466篇
  2016年   448篇
  2015年   306篇
  2014年   462篇
  2013年   1877篇
  2012年   509篇
  2011年   550篇
  2010年   529篇
  2009年   554篇
  2008年   495篇
  2007年   480篇
  2006年   404篇
  2005年   371篇
  2004年   333篇
  2003年   392篇
  2002年   375篇
  2001年   356篇
  2000年   412篇
  1999年   323篇
  1998年   336篇
  1997年   330篇
  1996年   320篇
  1995年   313篇
  1994年   328篇
  1993年   309篇
  1992年   337篇
  1991年   360篇
  1990年   288篇
  1989年   232篇
  1988年   244篇
  1987年   224篇
  1986年   261篇
  1985年   364篇
  1984年   344篇
  1983年   311篇
  1982年   327篇
  1981年   348篇
  1980年   293篇
  1979年   293篇
  1978年   264篇
  1977年   194篇
  1976年   204篇
  1975年   208篇
  1974年   153篇
  1973年   171篇
  1972年   130篇
排序方式: 共有10000条查询结果,搜索用时 37 毫秒
991.
Children do not choose what to eat based on health issues alone, and the high availability of non‐nutritious food in the environment can be a barrier to the consumption of healthy foods. Brazilian children are consuming processed, savoury, rich in fat, sodium and refined carbohydrates rather than more nutrient‐dense foods. Foods offered in public school meals and those sold in private school canteens in Brazil are subject to regulation, but not the snacks brought from home. This study identified the suggestions of public and private school students about the characteristics that a snack should present in order to be considered both healthy and palatable. A qualitative exploratory study using focus groups was conducted with 128 primary school students aged 7–10 years old. Interviews were transcribed and content analysis was conducted, generating three categories: (1) foods actually consumed during snack breaks; (2) examples of foods considered healthy and/or tasty for consumption during snack breaks; and (3) desired characteristics of a healthy and tasty snack. Foods of high energy density and low nutritional value were mentioned as the most consumed snacks, usually brought from home or purchased within/near the schools. Consumption of meals offered by the National School Meal Program was reported by only one‐third of the public school students. Fruits, natural juices and vegetables were considered healthy foods; sweet‐tasting preparations containing fruits were considered tasty; while fruits and natural fruit juices were considered both healthy and tasty. Sweet‐tasting preparations containing fruits were mentioned as examples of snacks with the desired healthy/tasty characteristics. The disparity between what was actually consumed and what was reported as ideal leads us to question the availability in retail stores of healthy yet palatable foods that meet this population's desires.  相似文献   
992.
Assuming a symmetric relation between returns and innovations in implied market volatility, Ang, A., Hodrick, R., Xing, Y., and Zhang, X. (2006) find that sensitivities to changes in implied market volatility have a cross‐sectional effect on firm returns. Dennis, P., Mayhew, S., and Stivers, C. (2006), however, find an asymmetric relation between firm‐level returns and implied market volatility innovations. We incorporate this asymmetry into the cross‐sectional relation between sensitivity to volatility innovations and returns. Using both portfolio sorting and firm‐level regressions, we find that sensitivity to VIX innovations is negatively related to returns when volatility is rising, but is unrelated when it is falling. The negative relation is robust to controls for other variables, suggesting only the increase in implied market volatility is a priced risk factor. © 2010 Wiley Periodicals, Inc. Jrl Fut Mark 31:34–54, 2011  相似文献   
993.
994.
Logistics optimization has significantly grown in popularity over the last few decades. Improvements in computing power, modeling software, and the willingness of companies to invest time in the modeling effort have allowed models that were once too unwieldy to solve to optimality to be solved quickly. This has led to a more wide‐spread recognition by logistics managers of the potential advantages of using optimization. The scope of logistics optimization in companies and organizations has expanded to address strategic, tactical, operational, and collaborative decision making. Spreadsheets, an analytical tool familiar to managers, have played a crucial role in the expanded modeling efforts of companies. Although optimization’s role in logistics has grown tremendously, there still are areas that remain to be explored that will allow it to achieve an even larger and more successful role in the management of companies. Additionally, there are some models that are still too large or too complex to currently solve to optimality, despite the advances in computing power and modeling/solving software.  相似文献   
995.
Searching for the best worker, a reliable supply alternative, or the most profitable investment is frequently delegated to an agent. This article develops a theory of delegated search. We show that the principal’s ability to delegate depends on the agent’s luck, her initial resources, and the contract that governs her search. With moral hazard, the optimal contract is characterized by performance deadlines with bonuses for early completion. If performance cannot be specified, the optimal search is implemented by an option‐to‐buy contract for the principal. If performance is partially specified, the optimal contract is a standard pay‐for‐performance arrangement.  相似文献   
996.
Using Hungarian firm-transaction level export data, we show that about one third of firm–destination and about one half of firm–product–destination export spells are short-lived, or temporary, each year. This is in odds with theories where comparative advantage is stable and market entry costs are sunk. We show how endogenous choice between variable and sunk cost trade technologies can explain the empirical importance and some characteristics of temporary trade. We build a model in which the likelihood of temporary trade depends on productivity and capital cost of the firm as well as well-known gravity variables of destinations. These predictions are borne out by the data; the likelihood of permanent trade, defined by a simple filter, rises with firm productivity, financial stability, proximity and GDP of destination countries.  相似文献   
997.
998.
Entrepreneurship is commonly held to be a vital force in the US and other economies. Yet, little is known regarding the efficacy of entrepreneurial efforts developed in one country but attempted elsewhere. In response to calls for testable theoretical models, scholars have begun to investigate empirically the attendant phenomena associated with the venture development process. This article describes efforts to test in another nation a nine-stage entrepreneurial process model of venture development derived and validated in the USA. While some development stages appear to exist similarly across borders, others may not be present. Further, the sequence of stages in the US-derived model may differ when compared internationally.  相似文献   
999.
1000.
BOOK REVIEWS     
Purpose: Companies engage in business relationships for a variety of reasons, including specialization, product development, and building competitive networks. Research has demonstrated that mergers and acquisitions (M&As) may challenge ongoing business relationships. The purpose of this article is to investigate whether and how competition authorities consider business relationships when evaluating M&As.

Methodology: The article uses the documentation from 450 M&As reported to the Swedish competition authority to capture the way in which an authority evaluates M&As. The Swedish competition authority evaluation corresponds to other national and international evaluation procedures.

Findings: The findings indicate that the competition authorities neglect an important aspect of business life, namely companies forming business relationships. The competition authorities evaluate M&As on the basis of risk for price increases, and consequently disregard such issues as heterogeneity in demand and offerings, and values built into existing business relationships.

Originality/Value/Contribution: The article contributes to research on business relationships through exploring how a public authority deals with such relationships. It also contributes to research on mergers and acquisitions through examining how these activities are evaluated by competition authorities. Furthermore, the article contributes to competition research by reflecting on competition law concerning M&A regulations in relation to business relationships.  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