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   10247篇
  免费   242篇
  国内免费   1篇
财政金融   1819篇
工业经济   880篇
计划管理   1775篇
经济学   2258篇
综合类   230篇
运输经济   56篇
旅游经济   170篇
贸易经济   1646篇
农业经济   422篇
经济概况   1201篇
信息产业经济   1篇
邮电经济   32篇
  2021年   59篇
  2020年   125篇
  2019年   173篇
  2018年   197篇
  2017年   238篇
  2016年   224篇
  2015年   161篇
  2014年   217篇
  2013年   942篇
  2012年   303篇
  2011年   322篇
  2010年   302篇
  2009年   327篇
  2008年   296篇
  2007年   272篇
  2006年   224篇
  2005年   195篇
  2004年   194篇
  2003年   212篇
  2002年   170篇
  2001年   215篇
  2000年   219篇
  1999年   195篇
  1998年   180篇
  1997年   206篇
  1996年   176篇
  1995年   181篇
  1994年   167篇
  1993年   175篇
  1992年   196篇
  1991年   192篇
  1990年   152篇
  1989年   153篇
  1988年   126篇
  1987年   121篇
  1986年   128篇
  1985年   180篇
  1984年   158篇
  1983年   173篇
  1982年   139篇
  1981年   169篇
  1980年   143篇
  1979年   161篇
  1978年   135篇
  1977年   120篇
  1976年   126篇
  1975年   106篇
  1974年   101篇
  1973年   85篇
  1972年   64篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
91.
For the allocation of heterogeneous items, it is known that the buyers-are-substitutes condition is necessary and sufficient to ensure that a pricing equilibrium can yield the same allocation and payments as the VCG mechanism. Furthermore, concavity of the corresponding transferable utility TU-game guarantees that this VCG outcome can also be achieved by an ascending price auction. We show that concavity, and hence the buyers-are-substitutes condition, holds for the TU-game of the assignment problem with general capacities. Therefore, the VCG mechanism is supported by a pricing equilibrium which can also be achieved by an ascending auction. We also show that the buyers-are-substitutes condition, and hence concavity, does not hold anymore for very natural and straightforward extensions of this problem. This shows that the necessity of the substitutes property is a considerable restriction on the applicability of the VCG mechanism.  相似文献   
92.
Foreign direct investment is of increasing importance in the European Union. This paper estimates the effect of taxes on foreign direct investment (FDI) flows and on three sub-components of these flows for the countries of the enlarged European Union. The model in the spirit of gravity equations robustly explains FDI flows between the 25 member states. Sample selection needs to be addressed in the estimation. We show that the different subcomponents of FDI should and indeed do react differently to taxes. After controlling for unobserved country characteristics and common time effects, the top statutory corporate tax rate of both, source and host country, turn insignificant for total FDI and investment into equity. However, high source country taxes clearly increase the probability of firms to re-invest profits abroad and lower the percentage of debt financed FDI. This might reflect profit re-allocation to avoid taxes. Market size factors have the expected signs.
Guntram B. WolffEmail:
  相似文献   
93.
94.
95.
Ventilator-associated pneumonia (VAP) accounts for the majority of nosocomial pneumonias, which may increase intensive care and prolonged hospital stays. Endotracheal tubes allowing continuous subglottic suctioning may reduce VAP; however, they are more expensive than standard endotracheal tubes not allowing continuous suctioning. he objective of this study was to measure the comparative costs associated with continuous subglottic suctioning endotracheal tubes (CSS-ETT) versus standard endotracheal tubes (S-ETT) among intubated patients and whether cost differential is offset by the occurrence of VAP in patients receiving either type of intubation. A retrospective chart review was conducted for 154 intubated adult patients (77 = S-ETT; 77 = CSS-ETT). The S-ETT group had one case of VAP; the CSS-ETT group had none. The mean total hospital charges were higher for the S-ETT group ($103,600; CSS-ETT= $88,500) (p = 0.3). Although the average number of intubation days and ICU days were greater for the CSS-ETT group, there were no cases of VAP compared to the S-ETT group. ased upon the one S-ETT VAP case and the VAP attributable costs, it is cost effective to use the CSS-ETT.  相似文献   
96.
97.
Metallic structured packings have found increasing use in the cryogenic distillation of air. An experimental program was performed to test the flammability of selected metal packings under simulated high oxygen concentration operating conditions. Aluminum flammability in gaseous oxygen has been shown to be very dependent upon argon dilution, and in the presence of liquid oxygen, strong energy releases have been observed. Brass packing exhibited an unexpectedly high relative flammability whereas copper has been found to be non-flammable in all tested oxygen purities. These findings suggest the use of copper structured packing in higher purity GOX/LOX regions of an air separation distillation column and aluminum structured packing in the remainder of the column.  相似文献   
98.
99.
As global temperatures increase, does accelerating climate change represent an existential crisis or a manageable challenge for the ski industry? Despite considerable evidence demonstrating the global ski industry is in the early stages of a climate-induced transition, global research on ski industry stakeholder perspectives shows varied levels of climate risk awareness, a focus on future vulnerability, and limited engagement in adaptation. Within North America, research has focussed on the physical climatic impacts to ski operations and possible skier responses, yet there lacks insight into industry perceptions on current and future climate vulnerability. This study fills this important knowledge gap using a Delphi survey to engage 52 leaders from across the continent in a dialogue on strategic climate responsiveness. Results demonstrate North American ski industry leaders’ climate risk perceptions range widely, and opinions diverge over if or how to respond at both an industry and destination scale. Simultaneously, industry experts believe mountain tourists increasingly value nature-based activities, place-bound products, and corporate responsibility. Analysing industry leaders’ responses through Enlightened Stakeholder theory highlights how aligning supply-side environmental management with demand-side tourist experiences may create opportunities for new partnerships, innovations, policies, and strategies needed to achieve climate-resilient and sustainable futures.  相似文献   
100.
This paper describes a research methodology which assesses the efficiency of consumer decision-making based on the types and amounts of informational cues used. A simple operational method is used to classify consumers into three levels of consumer efficiency based on how well they perform in assessing the optimal choice. The information chosen by perfectly efficient consumers, or those scoring at the maximum level of efficiency, is examined for indicators of optimal information seeking and decision-making techniques.  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