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   26643篇
  免费   2126篇
  国内免费   1448篇
财政金融   2031篇
工业经济   984篇
计划管理   4484篇
经济学   4092篇
综合类   2157篇
运输经济   308篇
旅游经济   466篇
贸易经济   2650篇
农业经济   1997篇
经济概况   2446篇
水利工程   8602篇
  2024年   152篇
  2023年   593篇
  2022年   704篇
  2021年   968篇
  2020年   1119篇
  2019年   960篇
  2018年   909篇
  2017年   1198篇
  2016年   1190篇
  2015年   1066篇
  2014年   1785篇
  2013年   2157篇
  2012年   2129篇
  2011年   2303篇
  2010年   1672篇
  2009年   1638篇
  2008年   1749篇
  2007年   1619篇
  2006年   1374篇
  2005年   1158篇
  2004年   827篇
  2003年   600篇
  2002年   469篇
  2001年   338篇
  2000年   291篇
  1999年   216篇
  1998年   195篇
  1997年   141篇
  1996年   153篇
  1995年   142篇
  1994年   120篇
  1993年   64篇
  1992年   75篇
  1991年   41篇
  1990年   13篇
  1989年   26篇
  1988年   14篇
  1987年   4篇
  1986年   9篇
  1985年   16篇
  1984年   11篇
  1983年   4篇
  1982年   3篇
  1981年   2篇
排序方式: 共有10000条查询结果,搜索用时 531 毫秒
111.
李红春 《时代经贸》2006,4(12):61-62
本文针时我国企业在反倾销共同应诉中的不合作或者“搭使车”问题,试图探讨行业协会作为一种治理机制,如何提供或设计一种有效的制度安排(如俱乐部规范),把一群相互依存的企业组织起来,并通过自主性努力克服不合作或“搭便车”,以取得长期的共同利益的实现。  相似文献   
112.
以油藏监测工作中的油藏压力监测为例,介绍了标准化工作在压力资料录取及解释分析中的作用。并用实例说明了标准化作业在油田开发方案的制定及油藏压力监测中的应用。  相似文献   
113.
Predicting the geo-temporal variations of crime and disorder   总被引:2,自引:0,他引:2  
Traditional police boundaries—precincts, patrol districts, etc.—often fail to reflect the true distribution of criminal activity and thus do little to assist in the optimal allocation of police resources. This paper introduces methods for crime incident forecasting by focusing upon geographical areas of concern that transcend traditional policing boundaries. The computerised procedure utilises a geographical crime incidence-scanning algorithm to identify clusters with relatively high levels of crime (hot spots). These clusters provide sufficient data for training artificial neural networks (ANNs) capable of modelling trends within them. The approach to ANN specification and estimation is enhanced by application of a novel and noteworthy approach, the Gamma test (GT).  相似文献   
114.
Recent approaches to sustainable development leave much room for policies at a local level. In fact, it is becoming evident that targets such as increasing resource productivity, preserving natural cycles, or extending the present level of welfare, are best pursued within the confines of a local area. In particular, environmental changes are best brought about by considering local systems of firms as cornerstones of cooperative strategies and using data on materials and energy use in physical terms. In this paper, an enterprise input–output model is developed for an industrial district, i.e. a local group of firms specialized in the production of a single final output. The model allows for a detailed quantitative analysis of materials and energy flows and the consequent generation of waste and pollution. As a planning tool, the model may be used to evaluate alternative scenarios, such as the possibility of re- using waste taking account of sustainability requirements. An empirical case study applies the model to an industrial district in Southern Italy producing leather sofas.  相似文献   
115.
辽河干流堤防安全泄量为5000m3/s,盘锦城市防洪工程竣工后,其安全泄量为6800m3/s。而盘山闸的设计泄流能力仅为3000m3/s。通过本模型试验研究进一步确定扩建工程方案的合理性。  相似文献   
116.
山前平原地下水侧向补给潜力空间变异模拟   总被引:1,自引:0,他引:1  
SWAT模型利用分辨率较高的DEM数据,可以估算山前地下水侧向补给的空间变异,并可以计算不同降水年型下补给量的差别。模拟需要对研究区进行填洼、流向确定、汇流和河网水系的提取四步运算,并对河道临界支撑面积的取值进行分析。分别模拟了平水年和丰水年两种降雨年型下研究区13个出水口的地下水侧向补给潜力。在研究区,由于地形的变化,导致山与平原交接断面上出水口的集水面积变异非常大,因此山前平原所接受的地下水侧向补给量的空间变异也非常大。不同的降雨年型下,降雨量转化为地下水侧向补给量的比例也不同。平水年的转化比例较小,丰水年的转化比例较大。应用SWAT模型时,与ArcView的拓展模块有机结合,可以更方便提取完整的大流域,划分出合理的子流域。  相似文献   
117.
Repeated measurements often are analyzed by multivariate analysis of variance (MANOVA). An alternative approach is provided by multilevel analysis, also called the hierarchical linear model (HLM), which makes use of random coefficient models. This paper is a tutorial which indicates that the HLM can be specified in many different ways, corresponding to different sets of assumptions about the covariance matrix of the repeated measurements. The possible assumptions range from the very restrictive compound symmetry model to the unrestricted multivariate model. Thus, the HLM can be used to steer a useful middle road between the two traditional methods for analyzing repeated measurements. Another important advantage of the multilevel approach to analyzing repeated measures is the fact that it can be easily used also if the data are incomplete. Thus it provides a way to achieve a fully multivariate analysis of repeated measures with incomplete data. This revised version was published online in June 2006 with corrections to the Cover Date.  相似文献   
118.
Yoshiharu Takamura 《Socio》2003,37(2):85-102
As a national project of Japan, plans for the relocation of several government agencies out of Tokyo have been ongoing. This paper is concerned with the problem of site selection for this project. The National Land Agency, the agency responsible for this project, has declared that the process of site selection should be rational, open to the public and easily understandable. In an effort to meet these requirements, we propose a consensus-making method for reaching a group decision, based on a combination of the analytic hierarchy process (AHP) and the Assurance Region model of data envelopment analysis (DEA). Several strategic uses of these methodologies, e.g., Delphi procedures, are also discussed. Based on these analyses, the “Wise Men” Committee for deciding the best site has chosen two from among ten contenders, one from the North-East and the other from the Central part of Japan, as candidates for the best relocation site. We could not discriminate between the two with respect to the multiple criteria chosen for evaluating sites. The Committee recommended the two sites to the Prime Minister at the end of December 1999. The Prime Minister reported this conclusion to the Diet. This topic is currently the focus of political discussions in the Diet. In this report, the authors summarize the decision-making processes that the Wise Men Committee followed, putting emphasis on the methodological aspects.  相似文献   
119.
结合对简单网络管理协议(SNMP)的研究,分析了Agent 网管代理开发包,并介绍了利用Agnet 实现IP电话系统中SNMP代理的过程。  相似文献   
120.
This paper addresses the following subjects: biotechnology and consumers, concern about risks, consumer acceptance, labelling of foods produced using biotechnology, the legal approach to consumer protection, and consumer protection policies relating to biotechnology products in the European Union, the United States, Turkey and global institutions such as the Convention for Biological Diversity (CBD) and the World Trade Organisation (WTO). It is likely that biotechnology will gain ground much more rapidly in the twenty‐first century than in the past. Despite rapid, detailed and precise advances in gene technology, its applications have not been the received with a great deal of consumer enthusiasm. Consumers have approached genetically modified foods with considerable apprehension and opposition. Consumer concerns about bioengineered food products focus on the questions of human health, environmental and social risks and benefits. The most important stages in the process of marketing new foods produced using biotechnology are to demonstrate user need and consumer acceptance. Generally, the technical complexity of biotechnology makes it difficult for consumers to understand details of the product and the specific attributes of biotechnology applications. Scientific uncertainty, the nature of consumer concerns and general reluctance to accept biotechnology products, increase the importance of consumer protection. Legal protection is a very important factor in the solution of new social problems related to technological advances. More specifically, consumer and environmental law support consumer protection related to foods produced with biotechnology. The basic principles of consumer law can be re‐formulated as consumer rights. Environmental law is a new phenomenon, but precautionary principles and public participation in decision‐making for environmental law are relevant to consumer protection relating to bioengineered food products.  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