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   17242篇
  免费   320篇
各国政治   815篇
工人农民   1391篇
世界政治   897篇
外交国际关系   666篇
法律   9842篇
中国共产党   2篇
中国政治   145篇
政治理论   3714篇
综合类   90篇
  2020年   127篇
  2019年   156篇
  2018年   1437篇
  2017年   1397篇
  2016年   1217篇
  2015年   261篇
  2014年   227篇
  2013年   1147篇
  2012年   419篇
  2011年   1204篇
  2010年   1208篇
  2009年   811篇
  2008年   972篇
  2007年   900篇
  2006年   232篇
  2005年   257篇
  2004年   393篇
  2003年   384篇
  2002年   201篇
  2001年   359篇
  2000年   337篇
  1999年   291篇
  1998年   156篇
  1997年   115篇
  1996年   131篇
  1995年   127篇
  1994年   129篇
  1993年   103篇
  1992年   160篇
  1991年   156篇
  1990年   147篇
  1989年   139篇
  1988年   161篇
  1987年   158篇
  1986年   160篇
  1985年   148篇
  1984年   157篇
  1983年   162篇
  1982年   99篇
  1981年   69篇
  1980年   83篇
  1979年   106篇
  1978年   85篇
  1977年   76篇
  1976年   69篇
  1975年   59篇
  1974年   50篇
  1972年   53篇
  1971年   56篇
  1969年   54篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
151.
Fifty-three clusters of blowfly eggs of the genus Calliphora vicina were observed in the laboratory up to the hatching stage under reproducible and virtually field-like conditions. Rearing the larvae was then continued up to pupation, the larval growth in length being recorded several times a day. As the object was to study the dependence of the larvae increase in length on the temperature conditions in vitro, the substratal humidity and food supply were kept unchanged during the entire study. The temperature ranged from 6.5 degrees C to 35 degrees C, with the temperature for the individual cluster kept constant during the entire developmental process. Data on about 5500 measured larvae were statistically evaluated. The basic result established was that in the case of the blowfly of the genus Calliphora vicina in vivo, all developmental stages relevant to the entomologic determination of the time of death depend on the temperature conditions: (1) the duration of the egg stage increases with decreasing temperature; (2) the speed of larval growth is slower at lower temperatures; (3) the maximal larval length is reached earlier at higher temperatures; (4) the mean value of maximal length decreases with increasing temperature; (5) larvae under all temperature conditions decrease in size after having reached their maximal length, the decrease in length being more rapid at higher temperatures; (6) constant temperatures over 30 degrees C lead to "stunted forms" which do not pupate and die; (7) constant temperatures under approximately 16 degrees C after the peak of growth has been reached inhibit the readiness to pupate, which causes the larvae to fall into a stationary state of rest, which will be interrupted only when the temperature is raised and resumption of the metamorphosis is thus induced. To allow rapid reconstruction of the larval age in general practice, the established growth data were set out in the form of a diagram designated isomegalendiagram, which permits temperature-fluctuation-related entomologic determination of the time of death with a maximum degree of accuracy.  相似文献   
152.
153.
154.
155.
156.
157.
158.
159.
160.
This study investigated the impact of the abolition of the tender years doctrine on custody decisions in divorce cases. This doctrine supported the presumption that the mother is the more suitable parent for young children. In March of 1981, the Supreme Court of the State of Alabama found this doctrine to be unconstitutional. To assess the hypothesis that this ruling had a significant effect on custodyrelated decisions, a sample of court records for divorce cases in an Alabama county was examined as representative of the state on a number of key variables. Overall, no significant differences were found on indicator variables for the comparisons before and after the ruling. There was neither an increase in custody grants to fathers nor an increase in custody requests by fathers.  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