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   37945篇
  免费   833篇
财政金融   7078篇
工业经济   3022篇
计划管理   6450篇
经济学   8455篇
综合类   377篇
运输经济   290篇
旅游经济   667篇
贸易经济   5902篇
农业经济   1868篇
经济概况   4596篇
邮电经济   73篇
  2021年   240篇
  2020年   422篇
  2019年   576篇
  2018年   767篇
  2017年   749篇
  2016年   721篇
  2015年   542篇
  2014年   811篇
  2013年   3827篇
  2012年   1039篇
  2011年   1157篇
  2010年   954篇
  2009年   1162篇
  2008年   1187篇
  2007年   1049篇
  2006年   1011篇
  2005年   921篇
  2004年   903篇
  2003年   923篇
  2002年   846篇
  2001年   812篇
  2000年   811篇
  1999年   704篇
  1998年   709篇
  1997年   688篇
  1996年   655篇
  1995年   598篇
  1994年   633篇
  1993年   637篇
  1992年   586篇
  1991年   609篇
  1990年   549篇
  1989年   469篇
  1988年   469篇
  1987年   474篇
  1986年   464篇
  1985年   675篇
  1984年   658篇
  1983年   647篇
  1982年   616篇
  1981年   512篇
  1980年   516篇
  1979年   520篇
  1978年   436篇
  1977年   400篇
  1976年   330篇
  1975年   297篇
  1974年   294篇
  1973年   280篇
  1972年   214篇
排序方式: 共有10000条查询结果,搜索用时 41 毫秒
991.
Market Size, Trade, and Productivity   总被引:25,自引:1,他引:25  
We develop a monopolistically competitive model of trade with firm heterogeneity—in terms of productivity differences—and endogenous differences in the "toughness" of competition across markets—in terms of the number and average productivity of competing firms. We analyse how these features vary across markets of different size that are not perfectly integrated through trade; we then study the effects of different trade liberalization policies. In our model, market size and trade affect the toughness of competition, which then feeds back into the selection of heterogeneous producers and exporters in that market. Aggregate productivity and average mark-ups thus respond to both the size of a market and the extent of its integration through trade (larger, more integrated markets exhibit higher productivity and lower mark-ups). Our model remains highly tractable, even when extended to a general framework with multiple asymmetric countries integrated to different extents through asymmetric trade costs. We believe this provides a useful modelling framework that is particularly well suited to the analysis of trade and regional integration policy scenarios in an environment with heterogeneous firms and endogenous mark-ups.  相似文献   
992.
Whether ENSO has affected U.S. macroeconomic performance has been a matter of dispute. To address the issue we explore whether there has been any co-cyclicality of ENSO fluctuations and the rates of inflation and economic growth over the 1894-1999 timespan and, failing this, whether aperiodic ENSO shocks have had any impact on these variables. Neither co-cyclicality nor aperiodic shocks are discernible. While ENSO may briefly influence the performance of particular sectors of the economy in particular regions, as documented by the previous literature, such locally-important effects vanish into the noise surrounding macroeconomic trends in an economy as large and complex as that of the U.S.  相似文献   
993.
994.
995.
The paper relates John. R. Commons view on the roleof human design in institutional evolution to the views thathave been advanced on this matter by F. A. Hayek, in German ordo-liberalism,and in constitutional political economy. It is argued that Commonsconcept of purposeful selection points in the direction ofa theoretical perspective that consistently integrates the notionsof institutional evolution and constitutional design.  相似文献   
996.
The guest editor, Peter Lloyd, outlines the scope of the Singapore Ministerial meeting of the WTO and assesses its achievements and disappointments.  相似文献   
997.
Recent years have seen a spate of empirical studies that have used cross-country regressions to examine a variety of possible determinants of long-term economic growth. The present study considers an additional, largely overlooked, explanatory variable: military spending. Consistent with Thompson’s (1974) hypothesis that enhanced national defense fosters economic growth by increasing the security of property rights, the military expenditures share of GDP is found to have a statistically significant positive impact on the growth rate of per capita GDP. This result is obtained for two alternative model specifications, a Barro-regression and a LISREL variant of that regression. The LISREL variant is motivated by Sala-i-Martin’s (1994) claim that the impact of government economic policies jointly, rather than extant government policies individually and separately, is "the phenomenon that really matters" for long-term economic growth.  相似文献   
998.
Objectives:

Knee cartilage damage is a common cause of referral for orthopedic surgery. Treatment aims to reduce pain and symptoms by repairing cartilage. Microfracture, the current standard of care, yields good short-term clinical outcomes; however, treatment might fail after 2–3 years. A Chitosan-Beta glycerolphosphate-based medical device (BST-CarGel) is used as an adjunct to microfracture and demonstrates improvements in quantity and quality of repaired tissue, potentially reducing the risk of treatment failure. This study aimed to establish the economic value of BST-CarGel vs microfracture alone in knee cartilage repair from the societal perspective, using Germany as the reference market.

Methods:

A decision tree with a 20-year time-horizon was constructed, in which undesirable clinical events were inferred following initial surgery. These events consisted of pain management, surgery, and total knee replacement. Clinical outcomes were taken from the pivotal clinical trial, supplemented by other literature. Data and assumptions were validated by a Delphi panel. All relevant resource use and costs for procedures and events were considered.

Results:

In a group of patients with all lesion sizes, the model inferred that BST-CarGel yields a positive return on investment at year 4 (with 20-year cumulative cost savings of €6448). Reducing the incremental risk of treatment failure gap between the device and microfracture by 25–50% does not alter this conclusion. Cost savings are greatest for patients with large lesions; results for patients with small lesions are more modest.

Limitations:

Clinical evidence for microfracture and other interventions varies in quality. Comparative long-term data are lacking. The comparison is limited to microfracture and looks only at costs without considering quality-of-life.

Conclusion:

BST-CarGel potentially represents a cost-saving alternative for patients with knee cartilage injury by reducing the risk of clinical events through regeneration of chondral tissue with hyaline characteristics. Since the burden of this condition is high, both to the patient and society, an effective and economically viable alternative is of importance.  相似文献   

999.
Benefit transfer is a method for estimating the value of environmental goods that involves the use of past information on identical or similar goods. This paper considers the extent to which benefit transfer can be based on prior distributions elicited from expert opinion. We propose two alternative methods to elicit the parameters of a prior distribution from experts on environmental valuation. An experiment is carried out on the value of National Parks in Spain. The results from the elicited distributions are compared with the information provided by onsite samples of visitors. The results indicate that individual experts made different predictions about the potential value of the policy areas that were diverse and unable to accurately predict the value for each policy site. However, the average across the elicited distributions approaches the estimated distribution with empirical data and accurately predicts the relative values for the two policy sites considered.  相似文献   
1000.
This article explores the characteristics of venture business and entrepreneurs in Korea to (1) identify technology transfer activities, (2) analyze the differences between technology transfer in linear and nonlinear venture businesses, and (3) guide more effective venture business policy and strategy. This empirical assessment reveals that entrepreneurs have insightful evaluations about their resources and capacities as well as expectations with regard to functions and features of science parks and incubators. Respondents from “linear model”-based start-ups tend to be older and have higher education, employ more basic research and development (R&D) and have more R&D-oriented careers, and have more varied work experience than “nonlinear”-based start-ups. The functions and features of science parks and incubators were generally not considered a critical influence on start-ups nor on the growth of venture businesses. Accordingly, alternative venture-nurturing strategies are discussed as being key to accelerate venture businesses growth.  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