全文获取类型
收费全文 | 24024篇 |
免费 | 4478篇 |
国内免费 | 214篇 |
专业分类
财政金融 | 1965篇 |
工业经济 | 2352篇 |
计划管理 | 4279篇 |
经济学 | 5718篇 |
综合类 | 2628篇 |
运输经济 | 219篇 |
旅游经济 | 155篇 |
贸易经济 | 4851篇 |
农业经济 | 3581篇 |
经济概况 | 2932篇 |
邮电经济 | 36篇 |
出版年
2024年 | 183篇 |
2023年 | 483篇 |
2022年 | 523篇 |
2021年 | 679篇 |
2020年 | 851篇 |
2019年 | 1154篇 |
2018年 | 910篇 |
2017年 | 1091篇 |
2016年 | 904篇 |
2015年 | 1105篇 |
2014年 | 1426篇 |
2013年 | 1840篇 |
2012年 | 2061篇 |
2011年 | 2107篇 |
2010年 | 2024篇 |
2009年 | 1870篇 |
2008年 | 1671篇 |
2007年 | 1613篇 |
2006年 | 1515篇 |
2005年 | 1328篇 |
2004年 | 796篇 |
2003年 | 513篇 |
2002年 | 434篇 |
2001年 | 376篇 |
2000年 | 232篇 |
1999年 | 148篇 |
1998年 | 103篇 |
1997年 | 81篇 |
1996年 | 70篇 |
1995年 | 41篇 |
1994年 | 47篇 |
1993年 | 55篇 |
1992年 | 74篇 |
1991年 | 93篇 |
1990年 | 37篇 |
1989年 | 38篇 |
1988年 | 19篇 |
1987年 | 10篇 |
1986年 | 8篇 |
1985年 | 16篇 |
1984年 | 15篇 |
1983年 | 17篇 |
1982年 | 23篇 |
1981年 | 11篇 |
1979年 | 11篇 |
1978年 | 10篇 |
1973年 | 8篇 |
1971年 | 9篇 |
1969年 | 10篇 |
1963年 | 9篇 |
排序方式: 共有10000条查询结果,搜索用时 93 毫秒
11.
当前小体积远端射频单元(Remote Radio Unit,RRU)主要是皮站级别的Pico-RRU,其重量和体积仍然难以满足掌上型的要求。为此,采用高集成度的AD9361芯片来实现长期演进(Long Term Evolution,LTE)宽带收发信机功能,配合时钟同步模块、放大器模块和控制接口电路等一起构建低成本的掌上型RRU。主要解决了基于AD9516的时钟同步、低相位噪声设计和高灵敏度接收机设计三个技术难点,成功实现了掌上型、高性能、低成本的设计目标。整个RRU样机尺寸为18 cm×10 cm×2 cm,质量约500 g,量产成本千元以内。测试表明,该RRU下行误差向量幅度(Error Vector Magnitude,EVM)小于3%,优于3GPP要求的8%;10 MHz带宽时上行接收机灵敏度优于3GPP要求的-93.5 dBm。 相似文献
12.
Using an extended LHARG model proposed by Majewski et al. (2015, J Econ, 187, 521–531), we derive the closed-form pricing formulas for both the Chicago Board Options Exchange VIX term structure and VIX futures with different maturities. Our empirical results suggest that the quarterly and yearly components of lagged realized volatility should be added into the model to capture the long-term volatility dynamics. By using the realized volatility based on high-frequency data, the proposed model provides superior pricing performance compared with the classic Heston–Nandi GARCH model under a variance-dependent pricing kernel, both in-sample and out-of-sample. The improvement is more pronounced during high volatility periods. 相似文献
13.
14.
15.
This paper analyzes the issue costs and initial pricing of bonds in the international market. In particular, we investigate the determinants of three components of issue costs: underwriter fee, underwriter spread (the difference between the offering price and the guaranteed price to the issuer), and underpricing (the difference between the market price and the offering price). Total underwriter compensation increases with the bonds' credit risk and maturity, but it is insignificantly related to issue size. Interestingly, underwriters appear to price some issue characteristics directly (by adjusting the fee) and other characteristics indirectly (by setting the guaranteed price). The two compensation components (fee and spread) are negatively related to each other. We provide evidence that this trade-off is consistent with income tax considerations, as well as with two-tier pricing by underwriters. We find no evidence of underpricing. 相似文献
16.
黄毅 《广西商业高等专科学校学报》2003,20(3):82-84
中国—东盟贸易自由区将是“全球第三大市场”。随着双边贸易谈判进行,东盟贸易对中国经济影响越来越大。同时,东盟贸易也给中国企业带来无限商机。为此,我们应该积极进行应对,调整我们的策略,尽量在东盟贸易中赢得市场。 相似文献
17.
In rational, efficiently functioning and complete markets, returns on derivative and underlying securities should be perfectly contemporaneously correlated. Due to market imperfections, one of these markets may reflect information faster. The use of high-frequency data and the choice for a small unit time interval to measure these lead-lag relations comes at the cost of some or many missing observations, causing traditional estimators to either under- or overestimate covariances and correlations. We use a new estimator to estimate lead-lag relationships between the cash AEX index, options and futures. We find that futures returns lead both options and cash index returns by approximately 10 minutes. The relationship between options and the cash market is not completely unidirectional. 相似文献
18.
Programme Evaluation with Unobserved Heterogeneity and Selective Implementation: The Mexican PROGRESA Impact on Child Nutrition 总被引:1,自引:0,他引:1
This paper considers the impact of Programa de Educación, Salud y Alimentación ( PROGRESA ), a large Mexican rural anti-poverty programme that had an evaluation sample in which overall treatment was randomly assigned to some communities but not others, on child nutrition. When we examine the impact of PROGRESA based on the presumption of randomized allocations, we find that PROGRESA had no or even a negative impact on child nutrition. However, not all children designated to receive nutritional supplements actually did so. Our preferred estimates – child fixed-effects estimates that control for unobserved heterogeneity that is correlated with access to the supplement – indicate a significantly positive and fairly substantial programme effect of the nutritional supplements on children 12–36 months. They imply an increase of about a sixth in mean growth per year for these children and a lower probability of stunting. Effects are somewhat larger for children from poorer communities but whose mothers are functionally literate. The long-term consequences of these improvements are non-trivial; its impact working through adult height alone could result in a 2.9% increase in lifetime earnings. 相似文献
19.
本文通过工程实例说明,提供了作者进行施工企业评估过程中对其对外承接项目评估的思路和方法.提出了施工企业对其在外所承接项目的权益是一种债权,同时明确了合理确定项目给企业所能带来的应收工程款以及取得应收工程款可能发生的风险是此类项目评估的核心. 相似文献
20.
德育教育应放在学校教育之首,充分发挥体育教学的特点和优势,寓德育教育于体育教学之中,培养学生学会做人、学会求知、学会生活、学会审美、学会健体. 相似文献