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   4762篇
  免费   147篇
  国内免费   31篇
财政金融   606篇
工业经济   323篇
计划管理   926篇
经济学   889篇
综合类   540篇
运输经济   39篇
旅游经济   35篇
贸易经济   541篇
农业经济   284篇
经济概况   746篇
邮电经济   11篇
  2024年   7篇
  2023年   39篇
  2022年   79篇
  2021年   146篇
  2020年   133篇
  2019年   63篇
  2018年   62篇
  2017年   116篇
  2016年   93篇
  2015年   123篇
  2014年   187篇
  2013年   243篇
  2012年   355篇
  2011年   458篇
  2010年   460篇
  2009年   333篇
  2008年   403篇
  2007年   384篇
  2006年   385篇
  2005年   368篇
  2004年   101篇
  2003年   109篇
  2002年   95篇
  2001年   93篇
  2000年   32篇
  1999年   30篇
  1998年   8篇
  1997年   10篇
  1996年   4篇
  1995年   2篇
  1994年   3篇
  1993年   5篇
  1991年   6篇
  1989年   2篇
  1987年   1篇
  1984年   2篇
排序方式: 共有4940条查询结果,搜索用时 15 毫秒
131.
近年来,我国政府公信力建设取得了巨大的成就,但也存在政策之间的协调性和行政体制的结构矛盾十分突出、政府公共服务和信息公开不能满足民众要求等问题. 要全面提升政府公信水平,就要深化行政体制改革,建立政府信用水平评价体系,推进政府信息透明化,完善政府对自身债务的管理,积极引导网络舆情.  相似文献   
132.
There have been a number of previous studies that examined the effects of yield- or revenue-based crop insurance products on input use of farmers. However, no study has specifically investigated the input use impacts of a cost-of-production (COP) crop insurance policy, even though this type of crop insurance is the predominant one used in several other countries outside of the United States (such as the Philippines and China). This article aims to theoretically and empirically examine the effect of a COP crop insurance product on farmers’ chemical input use. Our theoretical model suggests that the effect of COP insurance on input use can either be positive or negative, with the resulting impact depending on the strengths of (a) the traditional moral hazard effect of insurance (i.e., an input use decreasing effect); versus (b) the marginal incentives to apply more inputs due to input levels being the main determinant for expected indemnity amounts in this type of insurance (i.e., an input use increasing effect). A survey data set from corn farmers in the Philippines is then used to empirically illustrate how a particular COP insurance product influences input use in a real-life context. In this case, we find that COP insurance increases the use of chemical inputs (e.g., fertilizers and total chemical expenditure), implying that the positive marginal incentive to apply more inputs dominates the negative moral hazard effect.  相似文献   
133.
134.
Abstract

Objective: This study aimed to compare the cost-effectiveness of ramucirumab versus placebo for patients with hepatocellular carcinoma who progressed on sorafenib with α-fetoprotein concentrations (AFP) of at least 400?ng/ml in the United States.

Methods: A Markov model was constructed to assess the cost-effectiveness of ramucirumab. Health outcomes were measured as quality-adjusted life years (QALYs). With TreeAge software, the disease process was modeled as three health states: progression-free survival (PFS), progressive disease (PD), and death. Costs were extracted from the REACH-2 trial, and utility was derived from published literature. Incremental cost-effectiveness ratios (ICERs) were calculated to compare ramucirumab with placebo. Probabilistic sensitivity analyses were developed to examine the robustness of the results.

Results: In the base case analysis, ramucirumab therapy had a cost of $55,508.41 and generated 0.54 QALYs, while placebo therapy had a cost of $761.09 and generated 0.47 QALYs, leading to an additional $54,747.32 in costs and 0.07 QALYs. The ICER was $782,104.57 per QALY, which was much higher than the willingness-to-pay threshold of $100,000 per QALY. According to sensitivity analyses, the utility of PD in the two groups was the dominant parameter influencing the ICER.

Conclusion: Although ramucirumab was associated with prolonged survival for patients with advanced hepatocellular carcinoma who progressed on sorafenib treatment with an AFP of at least 400?ng/ml, it is not a cost-effective treatment from a United States payer perspective.  相似文献   
135.
We examine private issuance of public equity (PIPE) in China, and our results suggest that PIPE investors benefit from the price manipulation before and after issuance. These investors tend to cash out after lockup expiration and make large profits. We also find evidence that the trading of PIPE investors after lockup expiration is informed. Tests about the abnormal returns in the 3 years after lockup expiration suggest that at least part of the benefits PIPE investors receive come from wealth transfer from outside investors. Overall, PIPE issuers in China seem to use an opaque mechanism to compensate PIPE investors.  相似文献   
136.
Review of Quantitative Finance and Accounting - This paper examines the ability of mutual fund managers to time aggregate investor sentiment. Our results indicate that mutual fund managers alter...  相似文献   
137.
李政  朱明皓  温博慧 《财贸经济》2021,42(1):92-106
本文采用最新发展的广义方差分解谱表示方法,从频域视角考察全球15个主要国家间经济政策不确定性的短期与长期溢出效应,并依次从总溢出水平、方向性溢出水平以及影响因素三个层面进行分析.研究发现,(1)短期与长期下的不确定性总溢出水平呈现出截然不同的时序特征.(2)各国经济政策不确定性溢出水平与国际国内具体事件密切相关,不同类型的冲击事件所产生的溢出效应具有不同的周期长度.其中,一国货币政策、贸易政策的调整将导致其短期溢出水平显著提高,而紧缩性财政政策、政党更替及其他对经济具有负面影响的极端事件则会推动其长期溢出水平大幅上升.(3)金融开放度与贸易开放度较高的国家分别具有较高的短期溢入与长期溢入水平,发达国家与环太平洋地区国家分别呈现出较高的短期溢出与长期溢出.(4)对长短期溢出影响因素的回归分析表明,两国间的金融市场波动相关性和产业结构相似度将显著增强双方的短期溢出,而贸易规模和经济周期差异则对彼此间的长期溢出具有正向影响.  相似文献   
138.
在发电厂脱硫生产pH值控制过程中,运用MATLAB软件对过程控制进行系统辨识,建立控制系统的数学模型,把求得的数学模型应用于SMITH预估器的设计,在实际运用中取的良好的效果.设计目标随动的变参数自适应SMITH控制系统调节系统能及时以脱硫吸收塔出口二氧化硫折算值改变pH值设定值适应各种工况的变化,在保持稳定的二氧化硫脱除率情况下进一步调高调节系统响应的快速性,在稳定工况下提高石灰石浆液的利用率,提高脱硫运行的经济性.  相似文献   
139.
This paper investigates the determinants of board composition and its consequences on firm value in China by focusing on the impact of ultimate owner type and financial needs under the institution environment with government intervention and weak investor protection. We find that State‐Owned Enterprises (SOEs) are more likely to choose politically connected directors without professional backgrounds, but non‐SOEs are more likely to have independent directors, or politically connected directors with professional business backgrounds. Appointment of independent directors has no effect on firm value. Due to weak legal investor protection in China, a dominant shareholder can easily remove independent directors, as there is no mature market for directors. Politically connected directors without professional business backgrounds are negatively associated with a firm's value. Although such directors can help a company establish relationships with the government, their firms may suffer due to inferior professionalism.  相似文献   
140.
索非布韦是全球首个全口服抗丙型肝炎病毒药物。以2-溴代丙酸乙酯为起始原料,经过膦叶立德、Wttig、氧化、成环、氟化和官能团保护6步反应制备了索非布韦关键中间体(2R)-2-脱氧-2-氟-2-甲基-D-赤式戊糖酸γ-内酯-3,5-二苯甲酸酯,并对合成工艺进行了改进。改进后的工艺降低了成本,提高了反应器的容量,同时还提高了反应的收率,总收率由文献最高的29.0%提高到35.4%,具有一定的工业应用价值。  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