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   20281篇
  免费   545篇
各国政治   988篇
工人农民   781篇
世界政治   1576篇
外交国际关系   774篇
法律   12388篇
中国共产党   2篇
中国政治   214篇
政治理论   3973篇
综合类   130篇
  2020年   255篇
  2019年   329篇
  2018年   431篇
  2017年   467篇
  2016年   471篇
  2015年   346篇
  2014年   440篇
  2013年   2189篇
  2012年   501篇
  2011年   615篇
  2010年   466篇
  2009年   495篇
  2008年   557篇
  2007年   550篇
  2006年   533篇
  2005年   458篇
  2004年   509篇
  2003年   524篇
  2002年   406篇
  2001年   857篇
  2000年   797篇
  1999年   623篇
  1998年   297篇
  1997年   240篇
  1996年   230篇
  1995年   212篇
  1994年   221篇
  1993年   194篇
  1992年   379篇
  1991年   405篇
  1990年   380篇
  1989年   386篇
  1988年   380篇
  1987年   384篇
  1986年   365篇
  1985年   364篇
  1984年   326篇
  1983年   332篇
  1982年   216篇
  1981年   206篇
  1980年   166篇
  1979年   245篇
  1978年   182篇
  1977年   152篇
  1976年   142篇
  1975年   134篇
  1974年   147篇
  1973年   150篇
  1972年   125篇
  1971年   131篇
排序方式: 共有10000条查询结果,搜索用时 9 毫秒
131.
Some features of early child care are more prominent in Norway than in other countries, such as emphasis on the outdoor environment. Of general relevance and interest is the form of day care provided by forest day-care centers. Three ideas form the development of these centers placed in wild areas. First, throughout history, Norwegians have had a close attachment to nature and some parents want to provide their children with outdoor experiences at an early age. Second, urging children to play outdoors characterizes the image many parents have of a happy, healthy childhood. Third, provision of day care for children has always been restricted in western countries, forcing parents to invent types of service that can become part of an ecological system that promotes healthy development.The forest day-care centers developed recently represent a supplement to the wide typology of child care in the 21st century. The article outlines the connections between these ideas in general European and western history and Norwegian history and presents debate and decisions about a question dating from the last half of the 1980s. It concludes that the forest day-care centers are perhaps only a modern form of the original kindergarten concept, which started in Europe and America as gardens for children not gardens of children.  相似文献   
132.
133.
134.
135.
Deoxyribonucleic acid (DNA) typing of ribosomal ribonucleic acid (rRNA) genes was performed with a polymerase chain reaction (PCR) assay for species identification. A variable region of the 28S ribosomal RNA gene was amplified with primers complementary to flanking sequences phylogenetically well conserved. The products of twelve animal DNAs (human, Japanese monkey, dog, cattle, pig, cat, rabbit, mouse, rat, chicken, frog, and fish) were separated by polyacrylamide gel electrophoresis, each revealing a few bands ranging from 150 to 100 base pairs. The band patterns obtained from each DNA sample differed in number and size, which indicates the applicability of the method to species identification. Samples containing either as little as 1 pg of DNA or degraded DNA of 0.2 to 0.5 kb in length were able to give detectable bands. Postmortem human tissue DNAs were tested as an example. They showed a pattern identical to the human control one, which was distinct from those of the other animals examined.  相似文献   
136.
Social scientists have theorized about the cycle of domestic violence in family abuse. Little research has addressed dating violence as a consequence to the experience of domestic violence by children. This article deals with the self-reported experience of dating violence by high school students from abusive and nonabusive households. A survey was conducted of 1,353 students in a rural area of North Dakota. Results indicated that students from abusive households showed significantly higher incidence of dating violence than those from homes where no abuse was evident. However, less than one in five of the students from abusive home reported dating violence, providing little support for the cycle of violence hypothesis. Students from abusive homes viewed violence as negatively as students from nonabusive homes. Thus, while there are significant differences between the two groups, there are also important similarities. Although there is apparently a greater risk of dating violence among students who have experienced violence at home, these data do not support the idea of an inescapable pattern of violence among adolescents who have experienced violence themselves.  相似文献   
137.
138.
This paper describes a collaborative exercise intended to demonstrate whether uniformity of DNA profile results could be achieved between different European laboratories. It was shown that this goal can be obtained provided that a common protocol is followed (specifically the use of a common electrophoretic buffer as being the most important parameter). Generally, lower molecular weight loci (with lower molecular weight fragments) such as YNH24 perform better than higher molecular weight loci such as MS43a. The results of the exercise are discussed in relation to the objectives of the European DNA profiling group (EDNAP).  相似文献   
139.
The authors examine the characteristics of threatening and otherwise inappropriate communications sent to members of the U.S. Congress by a sample of 86 subjects, 20 of whom threatened assassination. We quote excerpts from these letters and provide quantitative data on such variables as the volume, duration, form, and appearance of such communications; the enclosures; the subjects' perceived relationships to the recipients; the thematic content of the communications; and the messages and threats communicated. Comparisons between 43 subjects who pursued encounters with members of Congress and 43 who did not revealed 17 factors associated with such pursuit. In this population, threateners were significantly less likely to pursue an encounter than inappropriate letter writers who did not threaten, regardless of the type of threat or the harm threatened. Inappropriate letters to members of Congress are compared with those directed to Hollywood celebrities. Mentally disordered persons writing to public figures often mention and sometimes threaten public figures other than those to whom the letters are addressed, which raises important issues regarding notification of endangered third parties and the sharing of information among protective agencies.  相似文献   
140.
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