全文获取类型
收费全文 | 17177篇 |
免费 | 835篇 |
国内免费 | 217篇 |
专业分类
财政金融 | 1313篇 |
工业经济 | 674篇 |
计划管理 | 2592篇 |
经济学 | 2918篇 |
综合类 | 1846篇 |
运输经济 | 180篇 |
旅游经济 | 412篇 |
贸易经济 | 5096篇 |
农业经济 | 931篇 |
经济概况 | 2267篇 |
出版年
2024年 | 47篇 |
2023年 | 259篇 |
2022年 | 238篇 |
2021年 | 422篇 |
2020年 | 675篇 |
2019年 | 584篇 |
2018年 | 541篇 |
2017年 | 555篇 |
2016年 | 477篇 |
2015年 | 482篇 |
2014年 | 772篇 |
2013年 | 1641篇 |
2012年 | 1198篇 |
2011年 | 1452篇 |
2010年 | 948篇 |
2009年 | 947篇 |
2008年 | 1552篇 |
2007年 | 1352篇 |
2006年 | 1237篇 |
2005年 | 870篇 |
2004年 | 571篇 |
2003年 | 399篇 |
2002年 | 256篇 |
2001年 | 184篇 |
2000年 | 138篇 |
1999年 | 93篇 |
1998年 | 69篇 |
1997年 | 63篇 |
1996年 | 47篇 |
1995年 | 38篇 |
1994年 | 24篇 |
1993年 | 10篇 |
1992年 | 13篇 |
1991年 | 9篇 |
1990年 | 6篇 |
1989年 | 5篇 |
1988年 | 4篇 |
1987年 | 1篇 |
1986年 | 2篇 |
1985年 | 10篇 |
1984年 | 9篇 |
1983年 | 13篇 |
1982年 | 7篇 |
1981年 | 6篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1973年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
讨论了美国NASA深空网(DSN)对深空飞船所采用的同波束干涉(SBI)技术概念和测量原理,并介绍了这一技术的应用和发展情况。 相似文献
32.
首先介绍了国际航运中合同性质发生改变的情况和解决问题的办法;接着分析了对贸易术语变形的处理,规定装卸港口应注意的事项,对转运的把握;最后分析了国际航运中货物风险的提前转移。 相似文献
33.
The Incredible Economics of Geoengineering 总被引:3,自引:1,他引:2
Scott Barrett 《Environmental and Resource Economics》2008,39(1):45-54
The focus of climate policy so far has been on reducing the accumulation of greenhouse gases. That approach, however, requires broad international cooperation and, being expensive, has been hindered by free riding; so far, little action has been taken. An alternative approach is to counteract climate change by reducing the amount of solar radiation that strikes the Earth—“geoengineering.” In contrast to emission reductions, this approach is inexpensive and can be undertaken by a single country, unilaterally. But geoengineering also has worrying consequences: it may harm some countries; it would not address ocean acidification; it would pose new risks. The fundamental challenge posed by this new technology is not free riding but governance: who should decide if and under what circumstances geoengineering should be used? 相似文献
34.
Tina Hviid Rydberg 《Finance and Stochastics》1997,1(3):251-257
Simple sufficient conditions for the existence of a unique equivalent martingale measure are provided. Furthermore, these
conditions give us a handle on situations where an equivalent martingale measure cannot exist. The existence of a unique equivalent
martingale measure is of relevance to problems in mathematical finance. Two examples of models for which the question of existence
was unresolved are studied. By means of our results existence of a unique equivalent measure up to an explosion time is proved. 相似文献
35.
This paper explores the explanatory power of Jensen's free cash flow hypothesis in managers' choice of LIFO versus FIFO. The association between FCF, and choice of inventory methods is based on the assumption that there is a potential conflict of interest between managers and shareholders when LIFO is the tax minimization method and that non-value-maximizing managers of firms with the FCF problem have incentives to choose FIFO, an income increasing method, in order to increase their compensation. However, since debt can act as a monitoring device and mitigate the agency problems of FCF, managers of firms with high FCF and high debt are less likely to choose FIFO than managers of firms with high FCF and low debt. The evidence is consistent with this expectation. 相似文献
36.
通信信号的识别与解调是通信侦察的重要研究内容,在通常情况下,通信信号的很多参数并不知道。本文介绍了一种基于通信信号码延迟自相关特性的码速率测量技术,并给出了码速率测量理论分析及基于硬件的实现技术,仿真和实验结果表明本方案具有较高的测量性能。 相似文献
37.
38.
鸡蛋壳制备乙酸钙冰雪融化剂的研究 总被引:5,自引:1,他引:4
以鸡蛋壳为原料,对高温煅烧分解蛋壳、中和法制备乙酸钙(CA)的最佳反应条件进行了研究,试验结果表明:在所选参数下,其产量最大.即反应温度为50℃,配料摩尔比为CaO:HAc=1:2.8,乙酸浓度为15 mol/L,石灰乳浓度(以氧化钙计)为1.3 mol/L.产品融冰试验表明:CA在环境温度为-10℃以上使用时,其融冰效果较好. 相似文献
39.
提出了基于无线射频技术(RFID)的零售企业生鲜食品的信息追溯技术和持续补库计划(CRP)策略,集成了整合发货和库存补货,并构建了用以计算最高库存量和配送周期的供应商管理库存模式下的补货数学模型,模型中充分考虑了生鲜食品的特性(腐坏),确保零售企业销售生鲜食品的质量安全.在通过采用RFID技术实时监控销售和库存数据的基础上,供应商能够依据模型在发货周期内确定最佳的货物配送时间和配送数量,主动补货,在保证食品安全的同时实现总的长期平均成本最小化. 相似文献
40.
Characterization and construction of optimal designs using the familiar optimality criteria, for example A-, D- and E-optimality
are well studied in the literature. However the study of the Distance Optimality (DS-) criterion introduced by Sinha (1970)
has very recently drawn attention of researchers. In the present article, we consider the singularly estimable full rank problem
of estimating the full set of elementary treatment contrasts using the DS optimality criterion in the set up of a one way
ANOVA model. Using a limit argument it turns out that a CRD in which difference between any two allocation numbers is at the
most unity is uniquely DS-optimal.
Acknowledgement. We are thankful to Prof. B. K. Sinha for suggesting the problem to us and many helpful discussions with him. We are also
thankful to the referees for drawing our attention to the reference of Bischoff (1995) and many helpful comments. 相似文献