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   38658篇
  免费   615篇
财政金融   6594篇
工业经济   2321篇
计划管理   6366篇
经济学   9094篇
综合类   675篇
运输经济   184篇
旅游经济   347篇
贸易经济   7990篇
农业经济   1144篇
经济概况   3876篇
信息产业经济   46篇
邮电经济   636篇
  2023年   111篇
  2021年   152篇
  2020年   287篇
  2019年   464篇
  2018年   2699篇
  2017年   2482篇
  2016年   1679篇
  2015年   436篇
  2014年   645篇
  2013年   2468篇
  2012年   1195篇
  2011年   2644篇
  2010年   2438篇
  2009年   2219篇
  2008年   2151篇
  2007年   2402篇
  2006年   672篇
  2005年   894篇
  2004年   896篇
  2003年   997篇
  2002年   663篇
  2001年   559篇
  2000年   505篇
  1999年   415篇
  1998年   486篇
  1997年   425篇
  1996年   436篇
  1995年   359篇
  1994年   370篇
  1993年   354篇
  1992年   363篇
  1991年   381篇
  1990年   345篇
  1989年   255篇
  1988年   264篇
  1987年   267篇
  1986年   262篇
  1985年   359篇
  1984年   357篇
  1983年   332篇
  1982年   284篇
  1981年   286篇
  1980年   283篇
  1979年   277篇
  1978年   226篇
  1977年   183篇
  1976年   182篇
  1975年   162篇
  1974年   149篇
  1973年   148篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
991.
Innovation is the engine of development for enterprises, and there is an increasing trend to adopt an open innovation strategy. However, how to manage external resources in an open, collaborative and complementary manner, and in a shared environment that will yield the greatest networking effects, it is a challenging task. Because there is no such a satisfactory model for an open innovation strategy that combine operational mechanisms with the management of, external resources. Thhis article tries to fill the gap by adopting a resource-based perspective to construct an overall open innovation (OOI) business model. In this model, external resources are classified as industrial and non-industrial entities, to enable the identification of the interaction methods between manufacturing enterprises and external resources. The management of external resources involved in a Technology Open Innovation (TOI) cycle is given particular attention that includes: 1) the classification of the external resources of a TOI, 2) the general mechanisms extracted to promote qualified resources in and unqualified resources out, and 3) a business model to conceptualize the collaboration between enterprises and external resources. A case study of TOI is also provided to empirically verify its feasibility. This paper contributes to the literature by providing an original operational model and mechanism design for an open innovation strategy that is capable of managing external resources effectively.  相似文献   
992.
The criminal nature of narcotics complicates the direct assessment of a drug community, while having a good understanding of the type of people drawn or currently using drugs is vital for finding effective intervening strategies. Especially for the Russian Federation this is of immediate concern given the dramatic increase it has seen in drug abuse since the fall of the Soviet Union in the early nineties. Using unique data from the Russian social network ‘LiveJournal’ with over 39 million registered users worldwide, we were able for the first time to identify the on-line drug community by context sensitive text mining of the users’ blogs using a dictionary of known drug-related official and ‘slang’ terminology. By comparing the interests of the users that most actively spread information on narcotics over the network with the interests of the individuals outside the on-line drug community, we found that the ‘average’ drug user in the Russian Federation is generally mostly interested in topics such as Russian rock, non-traditional medicine, UFOs, Buddhism, yoga and the occult. We identify three distinct scale-free sub-networks of users which can be uniquely classified as being either ‘infectious’, ‘susceptible’ or ‘immune’.  相似文献   
993.
Digitalisation of the health care system proceeds. Therefore it is to be expected that telemedicine applications will also be introduced into health care. Currently, the number of telemedicine applications in Germany is low and it is also scarce in comparison to foreign countries. This is striking because it is usually supposed that telemedicine applications have got a great potential to improve health care and reduce expenditures. Hence, this publication discusses offers, chances and the cost-effectiveness of telemedicine.  相似文献   
994.
High-quality science communication to the public depends to a large extent on the way research findings are translated into comprehensible language and common speech. In this communicative process, a reasonable evaluation of the trustworthiness of empirical findings, based on an adequate interpretation of statistical analyses, is absolutely crucial. This paper’s authors argue that the credibility of science is jeopardised by two compromising developments within science itself: on the one hand, an inflation of ostensible empirical evidence related to misuses and misinterpretations of the concept of statistical significance, and, on the other, a sensationalist overvaluation of the results of single studies instead of an adequate representation of the available body of evidence in a given scientific field.  相似文献   
995.
Protected areas are key to the conservation of global biodiversity and ecosystem services; however, their success is contingent upon adequate funding. One possibility to increase funding for park management is to “sell” a wider suite of ecosystem services “produced” by protected areas, such as carbon sequestration. We conducted 420 tourist surveys to analyze willingness to pay (WTP) for ecosystem service benefits via a conservation fee in the Tambopata National Reserve in Peru. We also interviewed eight tour operators about their perceptions of the proposed fee. The average stated WTP was 15 USD. Sixty-six percent of tourists stated they would pay 10 USD or more, which, if actually paid, would have resulted in 318,000 USD for park management in 2015. Most respondents stated they would pay an additional fee if it supported biodiversity conservation or local ecosystem services, such as water, but less than 10% of tourists were motivated by carbon sequestration as a reason to pay the fee. Most tour operators supported the additional fee. Our findings suggest that tourists are willing to pay higher fees to support conservation but that interest in paying for additional ecosystem services from parks may not extend to global and intangible benefits such as carbon sequestration.  相似文献   
996.
Many of the most active and most dangerous security challenges in the Asia-Pacific region are generally seen to involve a complex amalgam of material and ideational conflicts. There is surprisingly little consideration, however, of the role of the justice motive. This article explores the role of the justice motive in the context of three specific maritime and territorial disputes: Dokdo/Takeshima, the Senkaku/Diaoyu Islands, and the South China Sea. What explains its intensity? How does it affect political salience, tractability, and danger of conflict? What are the available mechanisms and prospects for resolving justice conflicts?  相似文献   
997.
Aim: To assess the cost-effectiveness of nutrition education by dedicated dietitians (DD) for hyperphosphatemia management among hemodialysis patients.

Materials and methods: This was a trial-based economic evaluation in 12 Lebanese hospital-based units. In total, 545 prevalent patients were cluster randomized to DD, trained hospital dietitian (THD), and existing practice (EP) groups. During Phase I (6 months), DD (n?=?116) received intensive education by DD trained on renal nutrition, THD (n?=?299) received care from trained hospital dietitians, and EP (n?=?130) received usual care from untrained hospital dietitians. Patients were followed-up during Phase II (6 months).

Results: At baseline, EP had the lowest weekly hemodialysis time, and DD had the highest serum phosphorus and malnutrition-inflammation score. The additional costs of the intervention were low compared with the societal costs (DD: $76.7, $21,007.7; EP: $4.6, $18,675.4; THD: $17.4, $20,078.6, respectively). Between Phases I and II, DD showed the greatest decline in services use and societal costs (DD: –$2,364.0; EP: –$1,727.7; THD: –$1,105.7). At endline, DD experienced the highest decrease in adjusted serum phosphorus (DD: –0.32; EP: +0.16; THD: +0.04?mg/dL), no difference in quality-adjusted life-years (QALY), and the highest societal costs. DD had a cost-effectiveness ratio of $7,853.6 per 1?mg decrease in phosphorus, compared with EP; and was dominated by THD. Regarding QALY, DD was dominated by EP and THD. The results were sensitive to changes in key parameters.

Limitations: The analysis depended on numerous assumptions. Interpreting the results is limited by the significant baseline differences in key parameters, suggestive of higher baseline societal costs in DD.

Conclusions: DD yielded the greatest effectiveness and decrease in societal costs, but did not affect QALY. Regarding serum phosphorus, DD was likely to be cost-effective compared with EP, but had a low cost-effectiveness probability compared with THD. Regarding QALY, DD was not likely to be cost-effective. Assessing the long-term cost-effectiveness of DD, on similar groups, is recommended.  相似文献   
998.
999.
One of the key challenges in the study of neighbourhood effects on work is to understand the pathways through which disadvantaged neighbourhoods impact the employment opportunities of residents. Endogenous explanations for neighbourhood effects focus on social life in these neighbourhoods, identifying mechanisms of social isolation, deviant work ethics and neighbourhood disorder. This article studies these mechanisms in a low‐income neighbourhood in the Netherlands. The case study shows that unfavourable socioeconomic outcomes can be indirect and unintended consequences of actions and choices in everyday life that are not directly concerned with work. Nevertheless, these individual actions and choices reflect local social practices that are influenced by the marginalized context in which residents lead their lives.  相似文献   
1000.
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