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   135361篇
  免费   3842篇
  国内免费   1篇
财政金融   26085篇
工业经济   11073篇
计划管理   21733篇
经济学   29831篇
综合类   1477篇
运输经济   963篇
旅游经济   2518篇
贸易经济   22261篇
农业经济   6185篇
经济概况   16829篇
信息产业经济   7篇
邮电经济   242篇
  2021年   860篇
  2020年   1666篇
  2019年   2437篇
  2018年   2354篇
  2017年   2549篇
  2016年   2724篇
  2015年   2132篇
  2014年   3453篇
  2013年   15501篇
  2012年   4285篇
  2011年   4210篇
  2010年   3780篇
  2009年   4407篇
  2008年   3996篇
  2007年   3338篇
  2006年   3652篇
  2005年   3653篇
  2004年   3167篇
  2003年   2967篇
  2002年   2918篇
  2001年   2679篇
  2000年   2619篇
  1999年   2228篇
  1998年   2112篇
  1997年   2119篇
  1996年   2000篇
  1995年   2007篇
  1994年   2010篇
  1993年   1976篇
  1992年   1971篇
  1991年   1883篇
  1990年   1742篇
  1989年   1598篇
  1988年   1519篇
  1987年   1530篇
  1986年   1606篇
  1985年   2396篇
  1984年   2270篇
  1983年   2063篇
  1982年   1927篇
  1981年   1914篇
  1980年   1876篇
  1979年   1788篇
  1978年   1609篇
  1977年   1606篇
  1976年   1363篇
  1975年   1254篇
  1974年   1172篇
  1973年   1158篇
  1972年   869篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
51.
In cocoa farming forestland is a production factor. Cocoa planting is easiest and production costs are lowest in tropical forest. Historically, therefore, once forestland has been exhausted in a given geographical area planters tend to diversify into other production systems to avoid the poverty (induced by increasing factor cost) of post-forest cultivation. In modern times however cocoa planters exist in a value chain and post-forest diversification could threaten multinational companies relying on rural planters for their raw material. In 2014 ten of the world’s largest chocolate multinationals combined, with more than $500 million in funding, to introduce a cocoa sustainability scheme called CocoaAction. In principle, CocoaAction and similar sustainability schemes sponsored by western multinational chocolate companies are interventions to empower cocoa planters and planting communities in West African countries. But in practice, as this article will show, these schemes are a response to diminishing returns in cocoa-producing communities and the prospect of diversification, and the resulting projection of a shortage in raw material. There are signs that diversification away from cocoa will be beneficial to cocoa planters and their communities. Cocoa sustainability schemes are therefore designed for the benefit of multinational chocolate companies and at the expense of diversification in West African countries.  相似文献   
52.
53.
We investigate the impact of housing wealth, credit availability and financial distress on college enrolment decisions. We find that housing wealth is negatively related to enrolment in public schools and positively related to enrolment in private schools. This evidence suggests that, on average, students substituted away from private schools towards public institutions during the recent financial crisis.  相似文献   
54.
While innovation has become a pervasive term, many of today’s organizations still find innovation elusive. One reason may be that much of what is being said about innovation contributes to misunderstanding. To truly manifest innovation and reap its benefits, one must recognize that innovation is three different things: innovation is an outcome, innovation is a process, and innovation is a mindset. Innovation as an outcome emphasizes what output is sought, including product innovation, process innovation, marketing innovation, business model innovation, supply chain innovation, and organizational innovation. Innovation as a process attends to the way in which innovation should be organized so that outcomes can come to fruition; this includes an overall innovation process and a new product development process. Innovation as a mindset addresses the internalization of innovation by individual members of the organization where innovation is instilled and ingrained along with the creation of a supportive organizational culture that allows innovation to flourish. Such an understanding defines necessary elements, considerations, and vernacular surrounding the term so that better decisions can be made, thereby enabling innovation and having a greater propensity to succeed.  相似文献   
55.
The main objective of this paper it to model the dynamic relationship between global averaged measures of Total Radiative Forcing (RTF) and surface temperature, measured by the Global Temperature Anomaly (GTA), and then use this model to forecast the GTA. The analysis utilizes the Data-Based Mechanistic (DBM) approach to the modelling and forecasting where, in this application, the unobserved component model includes a novel hybrid Box-Jenkins stochastic model in which the relationship between RTF and GTA is based on a continuous time transfer function (differential equation) model. This model then provides the basis for short term, inter-annual to decadal, forecasting of the GTA, using a transfer function form of the Kalman Filter, which produces a good prediction of the ‘pause’ or ‘levelling’ in the temperature rise over the period 2000 to 2011. This derives in part from the effects of a quasi-periodic component that is modelled and forecast by a Dynamic Harmonic Regression (DHR) relationship and is shown to be correlated with the Atlantic Multidecadal Oscillation (AMO) index.  相似文献   
56.
This paper focuses on entrepreneurship by academic leaders. With the use of patents, inventions, and spin‐offs to measure commercialization, and directors, research group leaders, and business owners as academic leaders, results, using a sample of more than 2,500 German researchers, show differences across academic leaders and commercialization. Findings for spin‐offs are different from those for patents and inventions. Academic leaders in sciences were more likely to commercialize. Doctoral degrees helped patents by business owners and spin‐offs by group leaders, whereas female business owners and female group leaders faced challenges patenting and inventing, respectively. For business owners, age increased the likelihood of patenting but lowered spin‐offs.  相似文献   
57.
Supersaturated designs (SSDs) constitute an important class of fractional factorial designs that could be extremely useful in factor screening experiments. Most of the existing studies have focused on balanced designs. This paper provides a new lower bound for the \(E(f_{NOD})\)-optimality measure of SSDs with general run sizes. This bound is a generalization of existing bounds since it is applicable to both balanced and unbalanced designs. Optimal multi and mixed-level, balanced and nearly balanced SSDs are constructed by applying a k-circulant type methodology. Necessary and sufficient conditions are introduced for the generator vectors, in order to pre-ensure the optimality of the constructed k-circulant SSDs. The provided lower bounds were used to measure the efficiency of the generated designs. The presented methodology leads to a number of new families of improved SSDs, providing tools for directly constructing optimal or nearly-optimal k-circulant designs by just checking the corresponding generator vector.  相似文献   
58.
59.
60.
Flash sale (FS) is a new business model that offers discounted products in limited numbers over a short period. In this paper we discuss the impact of strategic consumers on advance selling (AS) of new products on FS platforms. We first study the impact of strategic consumers on competing retailers adopting AS to sell a homogeneous new product. And find that the retailers’ AS profits and inventory quantities decrease with the strategic customers’ valuation and valuation decreasing rate. Then we analyse whether FS can mitigate the impact of strategic customers on retailers adopting AS for new products. We consider a newsvendor model involving only one retailer adopting AS to sell a new product. We derive the results by comparing this model with two counterpart models, namely the classical newsvendor model with no strategic customers and a newsvendor model with strategic customers where the retailer does not use FS under AS.  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