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   1281篇
  免费   67篇
  国内免费   2篇
财政金融   46篇
工业经济   383篇
计划管理   433篇
经济学   127篇
综合类   46篇
运输经济   13篇
旅游经济   9篇
贸易经济   78篇
农业经济   97篇
经济概况   118篇
  2024年   3篇
  2023年   16篇
  2022年   31篇
  2021年   49篇
  2020年   39篇
  2019年   22篇
  2018年   16篇
  2017年   36篇
  2016年   26篇
  2015年   70篇
  2014年   154篇
  2013年   110篇
  2012年   142篇
  2011年   140篇
  2010年   108篇
  2009年   57篇
  2008年   59篇
  2007年   50篇
  2006年   48篇
  2005年   54篇
  2004年   28篇
  2003年   24篇
  2002年   17篇
  2001年   6篇
  2000年   16篇
  1999年   10篇
  1998年   4篇
  1997年   4篇
  1996年   5篇
  1995年   2篇
  1994年   1篇
  1993年   1篇
  1990年   1篇
  1989年   1篇
排序方式: 共有1350条查询结果,搜索用时 15 毫秒
1.
In the U.S., virtually no new coal-fired power plants have been built in recent years. Both industry experts and academics seem to believe that no rational firm will build a new coal-fired plant. Will such a trend continue in the future? To provide insights into this question, we investigate the optimal decision of an electricity company with an irreversible and deferrable opportunity to build either a new coal-fired or natural gas-fired power plant as its new base-load resource. According to our real option analysis, the optimal decision depends on the location. In the case of the eastern U.S., it is optimal to choose a natural gas plant if a firm is given a choice among a new natural gas plant, a new coal plant and deferring the investment. However, contrary to the common sentiment in the industry and academia, building a new coal plant in the western U.S. is still more economical than building a new natural gas plant in the absence of emission pricing. Furthermore, introducing carbon pricing to western U.S. states, as California did, can substantially increase the probability that a firm will optimally choose a natural gas plant over a coal plant.  相似文献   
2.
This research analyses the impact of foreign direct investment on greenhouse gas emissions in the agriculture sector of developing countries. Panel data from 63 developing countries for the period 2005 to 2014 was used to estimate a dynamic econometric model by applying a system‐generalised method of moments. The empirical results indicate a positive impact of foreign direct investment in agriculture on the carbon dioxide equivalent emission intensity in developing countries. The results provide weak support for the pollution havens hypothesis and imply the importance of coordination between foreign direct investment and environmental policies.  相似文献   
3.
电力体制改革为油气管道企业用电成本管控提供了政策支持。在梳理电力改革政策的基础上,简要介绍了适用于油气管道企业的新电力政策,详细分析了我国油气管道企业存在的基本电费偏高、力调电费偏高、用电类型不合理、用电管理有待完善等用电现状及其根本原因。在上述分析的基础上,提出了选取合适的用电类别、选择合理的电费计费方式降低基本电费、提高功率因数降低力调电费、积极利用直购电政策、健全用电成本管控激励和考核机制等对策建议,以期为油气管道企业用电成本管控提供参考借鉴。  相似文献   
4.
贾逗 《价值工程》2021,40(2):109-110
伴随着供应链管理的应用与发展,越来越多的企业认识到必须充分利用内外资源保持自身的竞争实力。作为重要的外部资源,供应商管理关系到企业成本与收益的平衡,而要做好供应端的成本管理首先要做好供应商的选择和优化。针对CS公司的供应商管理现状及存在的问题,探索适应企业的可操作性强的对策,以期为我国大型油气企业的供应商管理实践提供一定的参考。  相似文献   
5.
民用气瓶也就是我们常说的液化气瓶,属于移动式高危产品,在人们日常生活中是必不可少的东西,因监管不完善导致每年发生的民用气瓶爆炸事件次数呈上升的状态,气瓶成了埋伏在我们周围的一个隐形“杀手”,严重威胁到人们的生命及财产安全,所以液化气市场需及时采取有效监管方案,彻底消除气瓶所带来的安全隐患。  相似文献   
6.
为了适应农药残留分析高灵敏度和快速性的趋势与要求,本方法选取农产品中具有代表性的苹果、梨、木耳、黄瓜、土豆、菠菜、西红柿作为基质,用QuEChERS-气相色谱-质谱法测定其中的有机磷、有机氯、拟除虫菊酯、氨基甲酸酯类等143种农药及其代谢物残留量。检出限LOD为0.002 mg/kg,定量限LOQ为0.005 mg/kg;各农药标准溶液在0.005 mg/L0.1 mg/L范围内与响应值(定量离子峰面积)有良好的线性关系;采用各基质进行了3个添加水平10平行的回收率试验,回收率为81.4%103.9%,RSD≤10.4%。本方法快速简便、经济高效,且具有较高的灵敏度,适用于农产品中农药残留的日常检测和快速筛查。  相似文献   
7.
ABSTRACT

The implications of national or regional energy policies for technical efficiency and environmental outcomes in electricity generation depend on fossil fuel input substitution. This study uses state level data to examine fossil fuel (coal and natural gas) substitution in electricity generation under increased availability of natural gas in the United States. We observe that changes in elasticities of substitution from pre-2009 to post-2009 differ across states suggesting that the effects of increased availability of inexpensive natural gas on electricity generation have been spatially heterogeneous. We rely on the observed heterogeneity to assess the effects of fossil fuel input substitution on technical efficiency and CO2 emissions. The results reveal that state level elasticity of substitution between natural gas and coal has a positive effect on technical efficiency and a negative effect on CO2 emissions. Therefore, future policy design and analyses should reflect the implications for regional elasticities of fossil fuel substitution and associated environmental outcomes.  相似文献   
8.
为研究上部覆盖层下伏页岩这一类型的滑坡失稳变形,需要确定其变形的潜在影响因素,从定量角度上分析这一类型滑坡灾害的变形演化问题。以容县六王镇西流河潜在滑坡为研究对象,借助钻孔勘探、室内试验和地质调绘,详细分析了西流河滑坡的工程地质概况,并推测其可能的变形演化机制,然后利用Geostudio数值软件建立西流河滑坡的渗流模型,模拟其在不同降雨工况下的渗流规律。研究发现:西流河滑坡在持续降雨过程中稳定性系数从1.224逐步降低至1.09,稳定性系数不断下降,滑坡体内由垂直入渗逐步转化沿滑动带稳定渗流;当遭遇极端暴雨情况(50年重现期)时,滑坡体内稳定渗流场显著增厚,饱和滑带土增多,滑坡安全储备达到极限。由此可以得出:上部覆盖层下伏页岩一类滑坡变形演化过程主要分滑坡体上部覆盖层堆积阶段,垂直入渗至页岩富水软化阶段和稳定渗流至潜在滑动带软化蠕变这3个阶段;其中上部覆盖层的高渗透性和下伏页岩的隔水特征是导致页岩风化带软化蠕变和稳定渗流场形成的关键因素。研究结果为上部覆盖层下伏页岩这一类滑坡影响因素的研究提供了一些证据,对研究滑坡演化变形机制具有借鉴意义。  相似文献   
9.
Major climate-cum-energy policies and respective impact projections rest on the widespread belief that increased energy efficiency can be equated with savings in energy use and emissions. This belief is flawed. Due to the rebound effect emissions savings from energy efficiency improvements will be generally less than what is technically feasible, or even be reversed. By means of an analytical general equilibrium model we demonstrate the latter to be true in a case that is both stark and relevant: if electricity generation is subject to a cap-and-trade scheme with partial coverage, increased efficiency of electric devices leads unambiguously to increased carbon emissions. The result implies that a proper distinction between the energy rebound and the carbon rebound is warranted, and that public policy must carefully consider the interactions between energy efficiency promotion and carbon pricing.  相似文献   
10.
ABSTRACT

This paper analyses the role of user-supplier relationships in the innovation dynamics of the Oil and Gas (O&G) industry, from an analysis supported by R&D and patent application data. This paper points to some recent interesting phenomena in the O&G sector, such as: (i) the remarkable advancement of two Chinese oil companies; (ii) the significant growth in O&G companies’ technological engagement in exploration and production (E&P) from the 2000s; (iii) the non-negligible increase in the application of O&G companies’ patents for renewable energy. Moreover, by working with the oil and gas chain complete, we show that the performance of the companies oil and gas equipment and services industry (O&GES) is restricted to the upstream activities. Finally, we bring up some arguments that have as objective relativise the typology of R&D intensity adopted by OECD.  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