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   6606篇
  免费   210篇
各国政治   338篇
工人农民   285篇
世界政治   554篇
外交国际关系   342篇
法律   3887篇
中国政治   48篇
政治理论   1330篇
综合类   32篇
  2023年   43篇
  2021年   33篇
  2020年   79篇
  2019年   111篇
  2018年   150篇
  2017年   155篇
  2016年   171篇
  2015年   106篇
  2014年   140篇
  2013年   764篇
  2012年   152篇
  2011年   197篇
  2010年   139篇
  2009年   186篇
  2008年   170篇
  2007年   178篇
  2006年   181篇
  2005年   131篇
  2004年   183篇
  2003年   159篇
  2002年   136篇
  2001年   244篇
  2000年   247篇
  1999年   181篇
  1998年   103篇
  1997年   102篇
  1996年   83篇
  1995年   88篇
  1994年   96篇
  1993年   98篇
  1992年   144篇
  1991年   130篇
  1990年   160篇
  1989年   146篇
  1988年   161篇
  1987年   156篇
  1986年   120篇
  1985年   129篇
  1984年   99篇
  1983年   86篇
  1982年   61篇
  1981年   60篇
  1980年   56篇
  1979年   58篇
  1978年   39篇
  1977年   32篇
  1976年   38篇
  1975年   32篇
  1974年   43篇
  1973年   34篇
排序方式: 共有6816条查询结果,搜索用时 15 毫秒
31.
32.
33.
With new technically advanced methods and computers at our disposal, the efficient market hypothesis is once again being debated. At the same time, we are witnessing an unprecedented growth in both existing and new financial markets. These new markets are often in economies which have just recently embraced free market economics; we term these stock markets infant markets. Such stock markets are obviously not efficient in allocating the supply of savings to productive capital. We do not test whether or not these infant markets are informationally efficient, but instead examine whether and how they are becoming more efficient. We propose modelling the excess returns of individual securities using a multi-factor model with time-varying coefficients and generalised auto-regressive conditional heteroskedastic (GARCH) errors. If the markets are becoming more informationally efficient or the agents are learning, we would expect this to manifest itself as the time-varying coefficients becoming more stable as time increases. We test our model using data on four Bulgarian shares. First, we estimate an AR(2) model and a GARCH-M(1,1) model for the shares. Then, we estimated our AR(2) model with time varying coefficients and GARCH type errors. We find varying levels of efficiency and varying speeds of movement towards efficiency within our sample of four shares.  相似文献   
34.
The enzyme activity of phosphoglucomutase (PGM) has been investigated in red cell haemolysates from 142 individuals and compared to the sub-type as determined by isoelectric focusing. The 10 phenotypes showed significant differences in PGM-activity which indicates that there is a correlation between the level of activity and the isolelectric point of homozygotes. No indication of silent alleles or alleles with reduced activity was found in this collective.  相似文献   
35.
The Green River Murder Investigation in King County, Washington, is currently the longest active serial murder investigation in U.S. history. During its course, over 26 separate scenes with from one to five victims each have been processed. The experience of the authors is presented in order to acquaint other agencies with techniques of outdoor scene processing that have evolved during recovery of remains from Green River and other skeletal cases.  相似文献   
36.
37.
38.
The population-adjusted rate of teenage suicide in King County, Washington, was reviewed for the 26 years from 1959 to 1984. For the entire period, the rate did not change significantly. An abrupt change did occur during the middle of this period, but, for reasons discussed in the text, this may well represent a change in procedures and philosophy of death certification rather than a real change in rate. Reasons for the apparent discrepancy with national statistics are discussed.  相似文献   
39.
40.
In the wake of the 1990 amendments to the Clean Air Act, localities across the United States initiated public information campaigns both to raise awareness of threats to air quality and to change behavior related to air pollution by recommending specific behavioral changes in the campaign messages. These campaigns are designed to reduce the health hazards associated with poor air quality and to avoid federal sanctions resulting from the failure to meet air quality standards. As in many other communities across the country, a coalition of government agencies and businesses initiated a public information campaign in the Atlanta metropolitan region to reduce certain targeted behaviors, mainly driving. A two‐stage model used to analyze data from a rolling sample survey shows that the centerpiece of the information campaign—air quality alerts—was effective in raising awareness and reducing driving in a segment of the population. When the overall information campaign was moderated by employers' participation in programs to improve air quality, drivers significantly reduced the number of miles they drove and the number of trips they took by car on days when air quality alerts were sounded. Public information campaigns can be successful in increasing awareness, but changing well‐established behaviors, such as driving, is likely to require institutional mediation to provide social contexts that support the behavioral change, as well. © 2003 by the Association for Public Policy Analysis and Management.  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