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   10252篇
  免费   515篇
各国政治   422篇
工人农民   313篇
世界政治   605篇
外交国际关系   325篇
法律   7397篇
中国政治   50篇
政治理论   1583篇
综合类   72篇
  2020年   188篇
  2019年   200篇
  2018年   226篇
  2017年   244篇
  2016年   267篇
  2015年   221篇
  2014年   224篇
  2013年   970篇
  2012年   230篇
  2011年   293篇
  2010年   271篇
  2009年   279篇
  2008年   265篇
  2007年   268篇
  2006年   264篇
  2005年   234篇
  2004年   283篇
  2003年   257篇
  2002年   241篇
  2001年   443篇
  2000年   366篇
  1999年   308篇
  1998年   117篇
  1997年   79篇
  1996年   83篇
  1995年   96篇
  1994年   102篇
  1993年   113篇
  1992年   208篇
  1991年   234篇
  1990年   225篇
  1989年   235篇
  1988年   212篇
  1987年   220篇
  1986年   194篇
  1985年   205篇
  1984年   162篇
  1983年   169篇
  1982年   105篇
  1981年   98篇
  1980年   68篇
  1979年   136篇
  1978年   98篇
  1977年   80篇
  1976年   76篇
  1975年   73篇
  1974年   89篇
  1973年   88篇
  1972年   74篇
  1971年   70篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
72.
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   
73.
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   
74.
In the forensic science laboratory, the recovery of spermatozoa from vaginal swabs, or vaginal cells from penile swabs, can help determine if sexual intercourse may have taken place. There are several methods used to recover spermatozoa and cells from the swabs before visualisation on a microscope slide and most of these methods use water. Phosphate buffered saline (PBS) is a non-toxic solution used in many biological laboratories. Unlike water, PBS prevents cells rupturing or shrivelling up due to osmosis. This study demonstrates that PBS can be used for the extraction of spermatozoa and cells from swabs and that PBS does not affect subsequent DNA profiling.  相似文献   
75.
76.
Toxicologic findings in the USS Iowa disaster.   总被引:5,自引:0,他引:5  
The toxicologic results from the 47 victims of the explosion on the USS Iowa are presented. Good correlation between carboxyhemoglobin saturations and cause of death was found. There were no correlations between blood cyanide concentrations and causes of death. Volatile analysis suggested postmortem ethanol production rather than antemortem ethanol ingestion. No drugs except nicotine were detected in any of the victims.  相似文献   
77.
Presents forensic medical characteristics of the specific features of stabbed and cut injuries of human skin and jersey. Suggests a complex of signs that will help determine some structural parameters of a knife blade and the conditions of its interaction with the injured site of human body.  相似文献   
78.
79.
The impact of high temperatures (24 to 39 degrees C) and low to moderately high humidities (20 to 70%) on the applicability of TLC systems for drug identification was studied during a 6 month climatologic cycle in Burkina Faso (West Africa). In general, the Rf values as observed on the plates were found to be substantially affected as compared with values obtained at temperate climates. Some TLC systems were more affected than others and the largest deviations of up to 30 Rf units were at low humidities. Tropical conditions also had a negative effect on the reproducibility of Rf values. However, when an Rf-correction procedure was applied, using reference mixtures of known drugs on each plate, accuracy as well as reproducibility of the resulting Rfc values were drastically improved and data thus corrected were found to be compatible with existing TLC data bases developed under moderate climatological conditions. The impact of high to extremely high humidities (70 to 100%) remains to be investigated.  相似文献   
80.
Hazardous waste management poses increasing problems for Canadian provinces and American states, given the vast quantities and types of wastes generated and the virtual inability to open new storage, treatment, or disposal facilities. The Canadian experience is very similar to the American one in many respects, except for the fact that three provinces (Alberta, Manitoba, and Quebec) have devised alternative approaches to siting that appear successful in moving beyond the political gridlock so common on this issue. In each of these cases, traditional, top-down approaches to siting have been eschewed in favor of a more comprehensive approach that includes extensive public participation, economic and social compensation packages, formal partnerships between public and private organizations, and direct links between siting proposals and other aspects of waste management, including waste reduction, recycling, and export/import control.  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