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   60967篇
  免费   2074篇
  国内免费   1057篇
财政金融   5092篇
工业经济   2417篇
计划管理   12571篇
经济学   10472篇
综合类   12463篇
运输经济   341篇
旅游经济   1006篇
贸易经济   7793篇
农业经济   4090篇
经济概况   7851篇
信息产业经济   2篇
  2024年   88篇
  2023年   618篇
  2022年   774篇
  2021年   1147篇
  2020年   1480篇
  2019年   986篇
  2018年   937篇
  2017年   1045篇
  2016年   1132篇
  2015年   1458篇
  2014年   3576篇
  2013年   4145篇
  2012年   4950篇
  2011年   6566篇
  2010年   4772篇
  2009年   4182篇
  2008年   4705篇
  2007年   4437篇
  2006年   4404篇
  2005年   3262篇
  2004年   2331篇
  2003年   1893篇
  2002年   1242篇
  2001年   1111篇
  2000年   735篇
  1999年   359篇
  1998年   176篇
  1997年   189篇
  1996年   138篇
  1995年   79篇
  1994年   65篇
  1993年   76篇
  1992年   51篇
  1991年   39篇
  1990年   39篇
  1989年   27篇
  1988年   20篇
  1987年   12篇
  1986年   12篇
  1985年   174篇
  1984年   192篇
  1983年   138篇
  1982年   99篇
  1981年   56篇
  1980年   74篇
  1979年   45篇
  1978年   36篇
  1977年   23篇
  1975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.
为解决实际应用中克拉维酸钾峰与后相邻杂质的分离度达不到要求的问题,建立了一种同时测定阿莫西林克拉维酸钾片中阿莫西林和克拉维酸钾含量的新方法,采用反相高效液相色谱法(RP-HPLC),Ultimate AQ-C_(18)色谱柱(4.6mm×250 mm,5μm),以pH值为4.4的0.05 mol/L磷酸二氢钠缓冲液为流动相,柱温为35℃,流速为1.0mL/min,检测波长为220nm。结果表明:阿莫西林和克拉维酸钾两主峰与相邻杂质得到完全基线分离,分离度大于1.5;克拉维酸钾对照品溶液质量浓度为0.050 0~0.500 1mg/mL时与峰面积的线性关系良好(r=0.999 8),平均回收率(n=9)为100.14%,RSD值为0.24%;阿莫西林对照品溶液质量浓度为0.100 0~1.000 1mg/mL时与峰面积的线性关系良好(r=0.999 9),平均回收率(n=9)为100.45%,RSD值为0.17%。与原有的《中华人民共和国药典》方法相比,新的阿莫西林克拉维酸钾片含量测定方法专属性好,准确度高,操作简便快捷,结果可靠,可作为一种质量控制方法。  相似文献   
32.
刘艳 《科技和产业》2018,(11):49-52
Catapults(弹射中心)作为一种新型研发组织形式,在英国创新发展战略的实施中扮演着重要角色。精准的组织功能定位、高效的组织管理运作模式和紧密的网络化组织关系,是Catapults组织管理模式创新的重要三大重要内容。为我国新型研发机构的培育和发展提供了良好的参考样本。  相似文献   
33.
The “industry nurturing agriculture” reforms and World Trade Organization accession led to dramatic growth in public expenditure and international trade in China’s agricultural sector. This article aims to estimate the effects of public expenditure and trade on agricultural productivity in China for 2004–2015. A semi-parametric production function with shape constraints is introduced to derive more accurate productivity before the productivity determinants are analyzed with an emphasis on public expenditure and trade. The empirical result shows that public expenditure and exports can effectively improve agricultural productivity, while imports have no significant effects. Policy implications are discussed in the context of supply-side reforms.  相似文献   
34.
[Objective] This study aims to investigate how place attachment and the quality of experience affect consumers' intention to repurchase Geographical Indication (GI) agricultural products. [Methodology] Based on the special functional value and symbolic meaning of GI agricultural products, we constructed a five-dimensional model of place attachment for GI agricultural products consumers. Expanding on the original two-dimensional place attachment model, we introduced three connection concepts: nature, society, and emotion. We also combined this model with the quality of experience model and consumer purchase intention model to form a research model of repurchase intention for GI agricultural products. A questionnaire survey was used to collect data (n = 340), and a partial least squares structural equation model was used to test the empirical evidence. [Research results] (1) Place attachment to Geographical Indication agricultural products significantly affects the quality of experience. (2) Quality of experience significantly affects consumer trust and repurchase intention. (3) Consumer trust significantly affects repurchase intention. (4) There is a mediating effect of experience quality between place attachment and repurchase intention; there is a mediating effect of trust in the relationship between quality of experience and repurchase intention. (5) There is a chain mediating effect of “place attachment→quality of experience→consumer trust→repurchase intention” in the model.  相似文献   
35.
This paper studied the role of municipal quality of life as a driver of strategic tax interactions among local governments. A number of studies point out the existence of strategic interactions using spatial econometric models in which the spatial weights are mostly based on non-economic criteria or basic economic variables such as per capita gross domestic product (GDP). We propose the more sophisticated well-being indicator of municipal quality of life as the driver for these interactions. To deal with the potential endogeneity, we rely on instrumental variable estimators. The empirical analysis focuses on the main local tax in Spain (property) and on municipalities with more than 50,000 inhabitants, and it confirms the relevance of differentials in quality of life for the understanding of tax choices.  相似文献   
36.
Abstract

The detrimental effects traditionally assigned to warfare in the development of pre-industrial economies have obscured the prominent role that military entrepreneurs played in economic development in this period. Historiography minimises the extent to which war and the concomitant strengthening of the central state provided a whole new range of opportunities for capital investment, a tendency that has been strengthened by the paradigm of Redlich’s ‘decline of the soldier-entrepreneur’ and the technological determinism of the debate on the Military Revolution among others. The aim of this introduction is to look into the background of this relative lack of interest and to reaffirm the mutual dependence of eighteenth-century state-formation and the business of war.  相似文献   
37.
在全面实施创新驱动发展战略的时代背景下,揭示中国高端装备制造业自主技术创新效率稳定性,测度相关因素的影响强度与方向,对揭示中国高端装备制造业自主技术创新规律,制定其发展策略具有重要指导意义。聚焦中国高端装备制造业自主技术创新效率稳定性及影响因素,采用DEA-Malmquist指数方法和Tobit回归模型进行实证研究,结果表明,中国高端装备制造业自主技术创新效率存在一定波动性,且各细分行业技术创新效率内部稳定性较差,产业自主技术创新效率整体稳定性不高;自主技术创新投入因素和环境影响因素对产业自主技术创新效率的影响具有较高的异质性,其中创新资金投入和人力资源投入对自主技术创新综合效率、纯技术效率及规模效率具有正向影响,而新产品开发投入和企业规模对自主技术创新综合效率、纯技术效率和规模效率的影响具有异质性,政策因素与市场因素分别具有显著和非显著负向影响,外源性创新因素具有显著正向影响,且影响强度较大。在此基础上,提出调整政府对高端装备制造业创新支持模式、加强外源性创新与智力引进等策略建议。  相似文献   
38.
This study evaluates a wide range of machine learning techniques such as deep learning, boosting, and support vector regression to predict the collection rate of more than 65,000 defaulted consumer credits from the telecommunications sector that were bought by a German third-party company. Weighted performance measures were defined based on the value of exposure at default for comparing collection rate models. The approach proposed in this paper is useful for a third-party company in managing the risk of a portfolio of defaulted credit that it purchases. The main finding is that one of the machine learning models we investigate, the deep learning model, performs significantly better out-of-sample than all other methods that can be used by an acquirer of defaulted credits based on weighted-performance measures. By using unweighted performance measures, deep learning and boosting perform similarly. Moreover, we find that using a training set with a larger proportion of the dataset does not improve prediction accuracy significantly when deep learning is used. The general conclusion is that deep learning is a potentially performance-enhancing tool for credit risk management.  相似文献   
39.
Prior literature indicates that quadratic models and the Black–Karasinski model are very promising for CDS pricing. This paper extends these models and the Black [J. Finance 1995, 50, 1371–1376] model for pricing sovereign CDS’s. For all 10 sovereigns in the sample quadratic models best fit CDS spreads in-sample, and a four factor quadratic model can account for the joint effects on CDS spreads of default risk, default loss risk and liquidity risk with no restriction to factors correlation. Liquidity risk appears to affect sovereign CDS spreads. However, quadratic models tend to over-fit some CDS maturities at the expense of other maturities, while the BK model is particularly immune from this tendency. The Black model seems preferable because its out-of-sample performance in the time series dimension is the best.  相似文献   
40.
We study the cost of shocks, that is, jump risk, with respect to reserve management when the reserve process is formulated as a drift‐switching jump diffusion with a reflecting barrier at 0. Inspired by the Brownian drift switching model, our model results in a more realistic dynamic behavior of international reserves than the buffer stock model. The new model can capture both the jump behavior in reserve dynamics and the leptokurtic feature of the increment distribution which has a higher peak and two asymmetric heavier tails than the normal distribution. Through the selection of an initial distribution that reflects certain steady state behaviors, the reserve process becomes a regenerative process. This selection enables us to derive a closed‐form expression for the total expected discounted cost of managing reserves, thus helping us to numerically find management strategies that minimize costs. The numerical results show that shocks at the reserve level have a significant effect on reserve management strategies and that model misspecification can result in nonnegligible additional costs.  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