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   25010篇
  免费   1346篇
各国政治   1084篇
工人农民   1153篇
世界政治   1601篇
外交国际关系   792篇
法律   16756篇
中国共产党   5篇
中国政治   160篇
政治理论   4638篇
综合类   167篇
  2021年   123篇
  2020年   506篇
  2019年   553篇
  2018年   734篇
  2017年   773篇
  2016年   843篇
  2015年   626篇
  2014年   660篇
  2013年   2652篇
  2012年   678篇
  2011年   696篇
  2010年   689篇
  2009年   731篇
  2008年   734篇
  2007年   686篇
  2006年   746篇
  2005年   633篇
  2004年   621篇
  2003年   524篇
  2002年   603篇
  2001年   864篇
  2000年   803篇
  1999年   635篇
  1998年   356篇
  1997年   279篇
  1996年   290篇
  1995年   277篇
  1994年   262篇
  1993年   276篇
  1992年   444篇
  1991年   475篇
  1990年   449篇
  1989年   439篇
  1988年   448篇
  1987年   427篇
  1986年   464篇
  1985年   457篇
  1984年   384篇
  1983年   372篇
  1982年   270篇
  1981年   239篇
  1980年   214篇
  1979年   317篇
  1978年   190篇
  1977年   158篇
  1976年   130篇
  1975年   151篇
  1974年   176篇
  1973年   146篇
  1972年   130篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
131.
Recent studies point to the potential theoretical and practical benefits of focusing police resources on crime hot spots. However, many scholars have noted that such approaches risk displacing crime or disorder to other places where programs are not in place. Although much attention has been paid to the idea of displacement, methodological problems associated with measuring it have often been overlooked. We try to fill these gaps in measurement and understanding of displacement and the related phenomenon of diffusion of crime control benefits. Our main focus is on immediate spatial displacement or diffusion of crime to areas near the targeted sites of an intervention. Do focused crime prevention efforts at places simply result in a movement of offenders to areas nearby targeted sites—“do they simply move crime around the corner”? Or, conversely, will a crime prevention effort focusing on specific places lead to improvement in areas nearby—what has come to be termed a diffusion of crime control benefits? Our data are drawn from a controlled study of displacement and diffusion in Jersey City, New Jersey. Two sites with substantial street‐level crime and disorder were targeted and carefully monitored during an experimental period. Two neighboring areas were selected as “catchment areas” from which to assess immediate spatial displacement or diffusion. Intensive police interventions were applied to each target site but not to the catchment areas. More than 6,000 20‐minute social observations were conducted in the target and catchment areas. They were supplemented by interviews and ethnographic field observations. Our findings indicate that, at least for crime markets involving drugs and prostitution, crime does not simply move around the corner. Indeed, this study supports the position that the most likely outcome of such focused crime prevention efforts is a diffusion of crime control benefits to nearby areas.  相似文献   
132.
Fragment     
  相似文献   
133.
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   
134.
135.
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   
136.
137.
Veto Players and Civil War Duration   总被引:1,自引:0,他引:1  
Civil wars show a remarkable variation in how long they last. Some end within days; others continue for decades. What explains the extreme intractability of some wars while others are resolved quickly? This article argues that conflicts with multiple actors who must approve a settlement (veto players) are longer because there are fewer acceptable agreements, information asymmetries are more acute, and shifting alliances and incentives to hold out make negotiation more difficult. This veto player approach to explaining variation in civil war duration is tested using a new dataset containing monthly data on all parties to each civil war begun since World War II. The statistical analysis shows a strong correlation between the number of veto players and the duration of civil war.  相似文献   
138.
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   
139.
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   
140.
Child custody evaluators with experience in mediation may be tempted to use mediation skills and strategies in their evaluation processes. This article explores the benefits and risks of blending mediation with evaluation, comparing the perspectives of professionals and clients.  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