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   25901篇
  免费   1238篇
  国内免费   518篇
财政金融   2540篇
工业经济   1229篇
计划管理   5709篇
经济学   4832篇
综合类   3019篇
运输经济   349篇
旅游经济   546篇
贸易经济   4346篇
农业经济   2050篇
经济概况   3037篇
  2024年   60篇
  2023年   546篇
  2022年   519篇
  2021年   821篇
  2020年   1029篇
  2019年   757篇
  2018年   711篇
  2017年   918篇
  2016年   874篇
  2015年   824篇
  2014年   1812篇
  2013年   2566篇
  2012年   2055篇
  2011年   2308篇
  2010年   1668篇
  2009年   1587篇
  2008年   1786篇
  2007年   1566篇
  2006年   1352篇
  2005年   1132篇
  2004年   760篇
  2003年   530篇
  2002年   380篇
  2001年   270篇
  2000年   224篇
  1999年   134篇
  1998年   102篇
  1997年   76篇
  1996年   57篇
  1995年   42篇
  1994年   40篇
  1993年   24篇
  1992年   39篇
  1991年   18篇
  1990年   6篇
  1989年   6篇
  1988年   7篇
  1987年   3篇
  1986年   11篇
  1985年   16篇
  1984年   11篇
  1983年   4篇
  1982年   3篇
  1981年   2篇
  1980年   1篇
排序方式: 共有10000条查询结果,搜索用时 19 毫秒
101.
102.
This research uses the Lotka–Volterra model to analyse the competition of innovation resource between two enterprises and studies the dynamic effects of environmental changes through the change of model parameters. The research finds that there are three possible results of the competition in innovation resource. That comprises ‘crowding out effect’, ‘unstable equilibrium’ and ‘stable equilibrium’. The results of competitive evolution are determined by enterprises’ interaction parameters. However, the natural growth rates, the initial resource possessions of both enterprises and the amount of regional innovation resource have a significant impact on the evolution of competition.  相似文献   
103.
Background: Inhibitor development to factor VIII (FVIII) hemophilia therapy results in increased complications and substantial economic costs. The SIPPET study, the first randomized controlled trial to compare the immunogenicity of plasma-derived FVIII (pdFVIII)/von Willebrand factor (VWF) and recombinant-DNA-derived FVIII (rFVIII), demonstrated higher inhibitor rates in previously untreated patients (PUPs) treated with rFVIII than in PUPs treated with pdFVIII/VWF.

Objective: To quantify the economic impact of treating PUPs with pdFVIII/VWF vs rFVIII.

Methods: An Excel-based clinical and economic model was developed from a US healthcare payer perspective and run over a 5-year period. The analysis utilized a cohort approach to model patient treatment and outcomes over a monthly cycle to quantify differences in costs of FVIII, bypassing agents, and hospitalizations for serious bleeds. Rates of high-titer inhibitor development were obtained from the SIPPET study. Patients developing high-titer inhibitors were treated with immune tolerance induction (ITI). Patients who developed low-titer inhibitors and those who did not develop inhibitors continued their usual FVIII treatment. Patients who were successfully treated with ITI returned to FVIII treatment, while unsuccessfully treated patients received bypassing agents. Total costs per treated patient were estimated and a one-way sensitivity analysis was conducted to quantify the impact of parameter uncertainty on the model outcomes.

Results: Total cumulative costs per patient over 5 years were $834,621 for pdFVIII/VWF patients and $1,237,163 for rFVIII patients, representing a total saving of $402,542 per patient over the 5-year period, for an average annual saving of $80,508 per patient.

Conclusions: Based on data from the SIPPET study, this analysis found that initiating FVIII treatment in severe hemophilia A PUPs with pdFVIII/VWF has the potential to offer substantial cost savings to healthcare payers, amounting to a one-third reduction in costs.  相似文献   
104.
105.
[目的]目前我国正处于关键的经济转型期,生态农业和生态旅游业作为生态文明建设的重要产业之一,其耦合发展对于存进产业结构优化升级具有重要作用。[方法]通过构建生态农业与生态旅游业指标体系,采用灰色关联法计算江苏省生态农业与生态旅游业的关联度,进一步通过耦合协调度模型分析两者的协调程度。[结果]生态农业系统与生态旅游系统中的旅游经济、旅游资源和旅游价值的关联度分别为0.719,0.673和0.621,大小顺序分别为旅游经济旅游资源旅游价值,而生态旅游系统与生态农业系统中生态系统、经济系统和社会系统的关联度分别为0.687,0.700和0.626,大小顺序分别为经济系统生态系统社会系统,耦合作用均分别为较强、较强和中等。2012~2016年江苏省生态农业和生态旅游业耦合度处于磨合阶段,但一直在增加,同时耦合水平经历了初级协调发展水平到中级协调发展水平的过程。[结论]江苏省生态农业和生态旅游业的耦合发展仍有进步的空间,今后应加强耦合发展机制,推动两大耦合产业走向更深更广的发展领域,促进生态文明建设,同时保证生态产业的可持续健康发展。  相似文献   
106.
ABSTRACT

This paper proposes a hybrid collaboration recommendation method that accounts for research similarities and the previous research cooperation network. Research cooperation is measured by combining the collaboration time and the number of co-authors who already collaborated with at least one scientist. Research similarity is based on authors’ previous publications and academic events they attended. A weighted directed graph is built to discover new collaborators by using direct and indirect connections between scientists. Moreover, a consensus-based system is built to integrate bibliography data from different sources. The experimental results show that our method improves the recommendation performances over other methods.  相似文献   
107.
108.
Cycling-inclusive urban planning is attracting attention worldwide because of the environmental, health, economic, and transport benefits inherent to cycling from the individual and the societal perspectives. The Czech Republic is one of the emerging cycling countries that are trying to promote and support cycling, but cycling mode shares are low because of the poor quality of the scarce infrastructure and the psychological barrier of the perceived lack of safety when cycling in mixed traffic. This study takes a multimodal approach based on the Theory of Planned Behaviour and focuses on the factors underlying the willingness to share the road from the perspective of cyclists and drivers: positive attitudes toward cycling, positive attitudes toward cyclists’ behavior, social norms toward cycling and anxiety to share the road. A web-based questionnaire was tailor-designed and administered in the Czech Republic via social networks, web forums, and the Civinet network, and a hybrid bivariate-ordered model tested the behavioral framework. Results show that the willingness to share the road as a cyclist or as a driver relates positively to positive attitudes towards cycling and cyclists’ behavior, and negatively to the anxiety of sharing the road. Moreover, mediator effects are observed and a clear relation emerges between the experience on the road as both a cyclist and a driver on the willingness to share the road as a cyclist. Lastly, results show that the factors underlying road sharing intentions are related significantly to gender, travel habits, and perceived personal and infrastructure-related barriers to cycling.  相似文献   
109.
[目的]科学合理的适宜性评价是确保耕地整理能够有效开展的前提条件,同时对于我国的耕地保护与粮食安全保障也具有极为重要的意义。[方法]该研究首先选取可以反映区域耕地整理适宜性的指标因子,然后参考胡学东提出的约束条件评价模型,引入区域生态安全和社会经济双重约束,对研究区域在双重约束下的耕地整理适宜性进行评价,并通过K-Means聚类法将研究区域的耕地整理适宜性分区进行合理划分。[结果]生态安全约束和社会经济约束对区域耕地整理适宜性水平具有重大影响,高生态安全约束与高社会经济约束会降低耕地整理的适宜性,低生态安全约束与低社会经济约束会提高耕地整理的适宜性。[结论]引入生态安全约束和社会经济约束后,可以在一定程度上反映山地区域在社会经济与生态安全双重约束状态下的耕地整理适宜性情况,耕地整理适宜性评价结果更加符合当地实际情况,约束条件评价模型可以更加合理准确地对处于约束条件下的耕地整理适宜性进行评价,是对耕地整理适宜性评价方法的丰富与完善。  相似文献   
110.
New technologies enable practitioners to communicate scents in advertisements on various media. The current research examines the importance of matching scent cues to the advertised product, and the joint effect of scent and other cues such as colour on consumer responses to advertising. A 4 × 2 experimental design was conducted, where participants (N = 603) were presented with scented colour print advertisements. Three hierarchical responses were measured: emotional response, attitude, and purchase intention. Findings reveal that higher congruence between scent and the advertised product heightens positive consumer response. Furthermore, this research stresses the significant joint effect of scent and colour cues, and supports the incongruence approach, suggesting that combining scents that are poorly congruent with other sensory cues enhance consumer response. Practical and theoretical implications are discussed.  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