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   16062篇
  免费   462篇
各国政治   952篇
工人农民   570篇
世界政治   1116篇
外交国际关系   741篇
法律   9434篇
中国共产党   1篇
中国政治   91篇
政治理论   3454篇
综合类   165篇
  2020年   185篇
  2019年   253篇
  2018年   316篇
  2017年   366篇
  2016年   411篇
  2015年   288篇
  2014年   351篇
  2013年   1901篇
  2012年   400篇
  2011年   404篇
  2010年   353篇
  2009年   367篇
  2008年   435篇
  2007年   436篇
  2006年   448篇
  2005年   361篇
  2004年   347篇
  2003年   379篇
  2002年   351篇
  2001年   578篇
  2000年   534篇
  1999年   447篇
  1998年   220篇
  1997年   205篇
  1996年   177篇
  1995年   176篇
  1994年   184篇
  1993年   159篇
  1992年   290篇
  1991年   319篇
  1990年   321篇
  1989年   304篇
  1988年   296篇
  1987年   306篇
  1986年   315篇
  1985年   268篇
  1984年   256篇
  1983年   249篇
  1982年   164篇
  1981年   166篇
  1980年   124篇
  1979年   233篇
  1978年   145篇
  1977年   135篇
  1976年   112篇
  1975年   147篇
  1974年   161篇
  1973年   152篇
  1972年   116篇
  1971年   112篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
141.
One of the remedies sought by state and local officials for the growing burden of federal mandates is a mandate reimbursement law. A major purpose of mandate reimbursement is to deter Congress from imposing excessive costs on state and local governments by making it fully accountable for its actions. The paper begins by extending the economic theory of grants to mandates and reimbursed mandates. It goes on to assess the benefits and costs of mandate reimbursement, and to distinguish mandates that should be reimbursed, should a reimbursement program prove desirable, from those that should not. Then, using the economic theory of grants and mandates, the paper compares reimbursed mandates with two alternatives for accomplishing the same objective, compensating grants and procedural rules. It concludes that the latter are more promising than mandate reimbursement.  相似文献   
142.
143.
This article surveys the voluminous economic literature on commoditybundling. While bundling has been widely studied, the vast majorityof the literature has focused on theoretical treatments of bundlingthat demonstrate a wide range of reasons why firms might engagein bundling. These papers generally contain restrictive assumptions,including assumptions regarding the existence of monopoly insome markets, and the nature of rivalry in others. The modelscontained in these papers also generally suppress the more obviousand ubiquitous reasons firms may use bundling. Moreover, thesemodels have not been subject to robustness checks, nor havetheir assumptions been tested empirically. This review of theeconomic literature generally confirms the US Solicitor General'sview in 3M v. LePage's regarding the underdeveloped state ofthe economics literature and its position that the US SupremeCourt should defer promulgation of antitrust standards for bundling.While the literature has demonstrated the possibility that bundlingcan generate anticompetitive harm, it does not provide a reliableway to gauge whether the potential for harm would outweigh anydemonstrable benefits from the practice. As a result, the widespreadapplication of the antitrust laws to bundling by firms can generatesignificant error costs by erroneously condemning or deterringefficient business practices. In the future, economists shouldseek to expand their understanding of both the anticompetitiveand procompetitive reasons firms engage in bundling. This willentail studying the reasons why bundling is adopted by firmswithout market power, relaxing the assumption of monopoly intheoretical models, and generating testable hypotheses and thedata to test them.  相似文献   
144.
145.
146.
147.
148.
149.
150.
The functional and nutritive circulation in the lungs is connected by anastomoses between the pulmonary and bronchial arteries. The anastomoses have the structure of blocked arteries from which arteriovenous anastomoses proceed to the peribronchial plexus. The pulmonary artery is provided with a flow impulse by the anastomoses, and oxygen-containing blood is admixed with the venous blood, thus forming an "aortalization" in the lungs. By diverting the bloodstream, venous blood can reach the bronchial artery. The peculiarities of the lung circulation are important for vital reactions in the form of macro- and microembolisms. Macroembolisms prove the functionality of the system if branches of the pulmonary artery are closed before the arteries are blocked. A hemorrhagic infarction either arises or does not arise, and the hemorrhagic infarction cannot exceed a certain limit. A microembolism is over and above the anastomoses. If the microembolism is greater, pressure in the arteria pulmonaris can cause blood from the pulmonary artery to overflow into the bronchial artery. Because arteriovenous anastomoses arise from the blocked arteries, microemboli can now reach the systemic circulation. Thus, the system described can explain the passage of microemboli into the systemic circulation, avoiding the capillaries of the lungs; on the other hand, larger microembolisms can prove the functionality of the system.  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