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   23247篇
  免费   1343篇
各国政治   987篇
工人农民   977篇
世界政治   1532篇
外交国际关系   795篇
法律   15756篇
中国共产党   3篇
中国政治   121篇
政治理论   4239篇
综合类   180篇
  2020年   472篇
  2019年   510篇
  2018年   663篇
  2017年   687篇
  2016年   770篇
  2015年   594篇
  2014年   627篇
  2013年   2423篇
  2012年   642篇
  2011年   653篇
  2010年   647篇
  2009年   675篇
  2008年   655篇
  2007年   640篇
  2006年   671篇
  2005年   548篇
  2004年   558篇
  2003年   481篇
  2002年   534篇
  2001年   883篇
  2000年   818篇
  1999年   651篇
  1998年   307篇
  1997年   267篇
  1996年   259篇
  1995年   257篇
  1994年   251篇
  1993年   250篇
  1992年   425篇
  1991年   456篇
  1990年   422篇
  1989年   415篇
  1988年   419篇
  1987年   376篇
  1986年   444篇
  1985年   422篇
  1984年   349篇
  1983年   337篇
  1982年   241篇
  1981年   221篇
  1980年   194篇
  1979年   318篇
  1978年   171篇
  1977年   143篇
  1976年   125篇
  1975年   153篇
  1974年   195篇
  1973年   149篇
  1972年   135篇
  1971年   118篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
141.
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   
142.
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   
143.
144.
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   
145.
146.
In this study, a new method was developed for the impurity profiling of illicit MDMA tablets. The extraction efficiency, linearity, repeatability and reproducibility of the method were evaluated. Eighty two MDMA tablets coming from presumed unrelated large seizures in 2004 (n >500 tablets) were analyzed by gas chromatography mass spectrometry (GC-MS) in order to assess the discrimination power of the method. The latter was found to be practical, robust, relatively easy to perform, highly discriminative and yielding good chromatography. In addition, some new impurities were detected and identified. Their chemical structures and mass spectra are reported.  相似文献   
147.
The legislator, in the German Federal Republic, has opted for a specific legal solution in relation to the protection of the embryo. Carola Müller, in this article, describes this regulation as well as the reasons that have led to its adoption. The article finishes with an exposition of the existing social discussion in German society and the effect that the law has had.  相似文献   
148.
We consider the problem of drawing inferences within a legal framework when a person is a suspect for two separate offences. Although we are primarily concerned with scientific evidence the issue inevitably arises as to how that evidence interacts with other, non-scientific evidence. We show that, in this particular context, the evidence can be conveniently classified into three categories that concern, respectively: the first crime only; the second crime only; and evidence that relates to similarities between the two crimes. Two case examples are considered and we consider DNA, fibres and eyewitness evidence. These are viewed from the perspective of a prosecutor who has to decide whether or not to charge a suspect with one or both crimes. Graphical sensivity analyses are presented which have features that are not intuitively obvious.  相似文献   
149.
More than a decade after NAFTA (North American Free Trade Agreement) entered into force, the environmental effects of agricultural trade liberalization in Mexico are still controversial, emerging, and not fully understood. This paper contributes to the literature that aims to explore trends in input use in the agricultural sector in Mexico during the post-NAFTA period among both commercial/industrial and traditional/rainfed farmers, and examines the influence of the national and multilateral institutional framework on these outcomes. We decompose the post-NAFTA agricultural production data into scale, technique and composition effects to estimate the impact that trade liberalization has had on the use of fertilizer and land use, two key agricultural inputs for which reliable aggregate data is available. We conclude that among commercial farmers patterns of crop type specialization and significant technological improvements have led to some declines in fertilizer use but they have been offset by growth in fertilizer use associated with growing agricultural output. Among traditional farmers increased output and specialization in land-intensive grain crops are contributing to an increase in land under cultivation and technological improvements show the potential, but not yet not the strength, to counteract these effects. We analyse the environmental institutional framework and rural development plans, observing that institutional weaknesses have, in several instances, reduced the environmental benefit of technique and composition effects. We conclude with recommendations about how the Mexican agricultural sector might reap the environmental benefits of international agricultural trade.  相似文献   
150.
This article reports the results of a study of the antecedents of long-term success in community mediation. Seventy-three mediation sessions were recorded and content analyzed. The participants were interviewed at two points: immediately after mediation and 4 to 8 months later. No relationship was found between the quality of the agreements—i.e., the extent to which they solved immediate problems- and long-term success as measured by compliance, improved relations between the parties, and the absence of new problems. On the other hand, joint problem solving by the disputants was related to complainant perceptions of improved relations with the other party. Also respondent perceptions that the mediation had been fair and that all the problems had come out were related to all aspects of long-term success in the eyes of the complainant. The latter results support a procedural justice analysis of mediation and underline the importance of mediator attention to the respondent.  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