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   7848篇
  免费   132篇
财政金融   670篇
工业经济   212篇
计划管理   612篇
经济学   812篇
综合类   43篇
运输经济   14篇
旅游经济   29篇
贸易经济   589篇
农业经济   180篇
经济概况   731篇
水利工程   4087篇
邮电经济   1篇
  2018年   228篇
  2017年   235篇
  2016年   205篇
  2015年   120篇
  2014年   185篇
  2013年   499篇
  2012年   243篇
  2011年   229篇
  2010年   187篇
  2009年   213篇
  2008年   207篇
  2007年   248篇
  2006年   201篇
  2005年   152篇
  2004年   181篇
  2003年   143篇
  2002年   131篇
  2001年   103篇
  2000年   126篇
  1999年   118篇
  1998年   137篇
  1997年   108篇
  1996年   124篇
  1995年   117篇
  1994年   120篇
  1993年   114篇
  1992年   131篇
  1991年   129篇
  1990年   125篇
  1989年   104篇
  1988年   107篇
  1987年   112篇
  1986年   114篇
  1985年   116篇
  1984年   110篇
  1983年   102篇
  1982年   103篇
  1981年   121篇
  1980年   120篇
  1979年   108篇
  1978年   136篇
  1977年   145篇
  1976年   142篇
  1975年   112篇
  1974年   119篇
  1973年   107篇
  1972年   94篇
  1971年   96篇
  1969年   92篇
  1968年   88篇
排序方式: 共有7980条查询结果,搜索用时 15 毫秒
71.
This article was prepared by Dr L. V. Defris and J. S. McDonnell of the Institute research staff. The authors wish to thank Professor R. F. Henderson and Dr P. J. Sheehan for their helpful comments.  相似文献   
72.
73.
The suitability of age-specific birth proportions (ASBP), or percentage distribution of births, as a rough and ready index of fertility change was analyzed by establishing a theoretical framework for its limitations and uses. The discussion suggested that the utility of ASBP as an indicator of fertility change depends on the characteristics and behavior of the population being considered. The concept was then empirically applied to birth trends in Japan and Singapore for 2 different time periods. Analysis suggested that ASBP trends in Japan reflected changes in age-specific fertility rates relative to general fertility rate as well as trends in parity distribution. The Singapore analysis was more complicated, raising different issues. As very limited empirical work has been done on ASBPs, the utility of ASBPs as an indicator of fertility change cannot be definitely ascertained. It was suggested however that ASBP trends may be applicable in countries where the age distribution of fertile-aged women is fairly stable. More empirical research should be done on ASBP trends in other countries, the behavior of A matrix as discussed in this paper, and useful empirical relationship of ASBP with other fertility measures.  相似文献   
74.
In our earlier paper [Srivastava, Agnihotri and Dwivedi (1980)] the dominance of double k-class over k-class with respect to exact mean squared error matrix criteria is established. It is observed that given a member of k-class, one can pick up a member of double k-class that will provide an improved estimator of the coefficients. This result prompted us to study the exact finite sample properties of the double k-class estimator. For this, we have considered a structural equation containing two endogenous variables and have investigated the properties of double k-class estimators of the coefficients of explanatory endogenous variables assuming characterizing scalars to be non-stochastic.  相似文献   
75.
Indian censuses provide useful data on livelihood. These data give a picture of the distribution of population deriving their living from different economic activities. According to the 1951 census, 73 cities in the country had a population over 1 lakh. These cities were, more or less, evenly distributed in the different States of the Union. Of the populations in these cities combined, nearly 40% derived its livelihood from the services and miscellaneous sources, approximately 1/4 from production other than cultivation, 1/4 from commerce, and the remaining few from transport and agriculture. These averages were fairly similar for large and small cities. Of the 32 largest cities which showed predominance of their population in 1 or more livelihood, there were about 10 in industrial-manufacturing, 6 in commerce, 9 in transport, and 10 in services. 2 of the 3 port cities, Bombay and Madras, were broad-based in employment while Calcutta was predominant in commerce. There was little uniformity in the livelihood patterns of capital cities.  相似文献   
76.
Conclusion Recognizing the fact that provision of mixed public goods can result in both consumption externalities of the Samuelsonian variety as well as production externalities we set out to extend the earlier results of Rao and Kalpagam (1977) on the effect of public goods on economic growth. In so doing, we considered three standard specifications of production externalities and enlarged the concept of consumption displacement. Our basic conclusion is that the results of our earlier paper remain valid under the more general conditions set out in this paper.  相似文献   
77.
78.
79.
80.
1.  The ideal guide vanes of a reaction turbine realized in the form of dual-regulation guide vanes maintain impact-free entry of the flow into the runner's blading in a wide range of regulation of the turbine's flow rate.
2.  On account of this, the optimum operating conditions (maximum values of efficiency and minimum hydraulic losses) will be maintained in practially the whole range of change in the turbine's power, since the conditions of impact-free entry, efficient passage of the flow in the runner's blade cascade, and normal exit from the runner characteristic of the optimum conditions will be maintained.
3.  The use of dual-regulation guide vanes will make it possible to abandon use of dual-regulation (Kaplan) turbines and switch to the use of ecologically clean propeller (rigid-blade) turbines, which possess high speed and capacity while preserving their energy qualities; and in single-regulation turbines, to get a significant increase in average efficiency and generation of electricity at hydroelectric stations.
Translated from Gidrotekhnicheskoe Stroitel'stvo, No. 9, pp. 36–40, September, 1994.  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