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   1568篇
  免费   88篇
各国政治   98篇
工人农民   49篇
世界政治   133篇
外交国际关系   123篇
法律   648篇
中国政治   5篇
政治理论   584篇
综合类   16篇
  2023年   12篇
  2022年   10篇
  2021年   16篇
  2020年   42篇
  2019年   51篇
  2018年   73篇
  2017年   87篇
  2016年   85篇
  2015年   43篇
  2014年   62篇
  2013年   236篇
  2012年   51篇
  2011年   53篇
  2010年   59篇
  2009年   61篇
  2008年   52篇
  2007年   49篇
  2006年   39篇
  2005年   48篇
  2004年   41篇
  2003年   40篇
  2002年   47篇
  2001年   31篇
  2000年   28篇
  1999年   28篇
  1998年   21篇
  1997年   28篇
  1996年   13篇
  1995年   16篇
  1994年   9篇
  1993年   18篇
  1992年   12篇
  1991年   11篇
  1989年   9篇
  1988年   10篇
  1987年   14篇
  1986年   10篇
  1985年   6篇
  1984年   12篇
  1983年   12篇
  1982年   10篇
  1979年   6篇
  1978年   8篇
  1975年   5篇
  1974年   6篇
  1973年   8篇
  1971年   8篇
  1970年   7篇
  1968年   6篇
  1967年   9篇
排序方式: 共有1656条查询结果,搜索用时 15 毫秒
861.
Why do great powers take such different approaches to the issue of nuclear proliferation? Why do states oppose nuclear proliferation more vigorously in some cases than in others? In short, what explains great power nonproliferation policy? To answer these questions, this article tests two competing theories of nonproliferation policy. The first, political relationship theory, suggests that states oppose nuclear proliferation to their enemies but are less concerned when friends acquire nuclear weapons. The second, power-projection theory, argues that states oppose the spread of nuclear weapons to states over which they have the ability to project military power because nuclear proliferation in those situations would constrain their military freedom of action. In contrast, states will be less likely to resist, and more likely to promote, nuclear proliferation to states against which they cannot use force. To test these hypotheses, this article uses evidence from great power nonproliferation policy from 1945 to 2000. While both theories find some support, the power-projection theory performs significantly better. The findings of this article have important implications for international relations theory and US nonproliferation policy.  相似文献   
862.

Objectives

Explore Bayesian spatio-temporal methods to analyse local patterns of crime change over time at the small-area level through an application to property crime data in the Regional Municipality of York, Ontario, Canada.

Methods

This research represents the first application of Bayesian spatio-temporal modeling to crime trend analysis at a large map scale. The Bayesian model, fitted by Markov chain Monte Carlo simulation using WinBUGS, stabilized risk estimates in small (census dissemination) areas and controlled for spatial autocorrelation (through spatial random effects modeling), deprivation, and scarce data. It estimated (1) (linear) mean trend; (2) area-specific differential trends; and (3) (posterior) probabilities of area-specific differential trends differing from zero (i.e. away from the mean trend) for revealing locations of hot and cold spots.

Results

Property crime exhibited a declining mean trend across the study region from 2006 to 2007. Variation of area-specific trends was statistically significant, which was apparent from the map of (95 % credible interval) differential trends. Hot spots in the north and south west, and cold spots in the middle and east of the region were identified.

Conclusions

Bayesian spatio-temporal analysis contributes to a detailed understanding of small-area crime trends and risks. It estimates crime trend for each area as well as an overall mean trend. The new approach of identifying hot/cold spots through analysing and mapping probabilities of area-specific crime trends differing from the mean trend highlights specific locations where crime situation is deteriorating or improving over time. Future research should analyse trends over three or more periods (allowing for non-linear time trends) and associated (changing) local risk factors.  相似文献   
863.
We have studied the degradation of sebaceous fingerprints on brass surfaces using silver electroless deposition (SED) as a visualization technique. We have stored fingerprints on brass squares either (i) in a locked dark cupboard or (ii) in glass‐filtered natural daylight for periods of 3 h, 24 h, 1 week, 3 weeks, and 6 weeks. We find that fingerprints on brass surfaces degrade much more rapidly when kept in the light than they do under dark conditions with a much higher proportion of high‐quality prints found after 3 or 6 weeks of aging when stored in the dark. This process is more marked than for similar fingerprints on black PVC surfaces. Identifiable prints can be achieved on brass surfaces using both SED and cyanoacrylate fuming (CFM). SED is quick and straightforward to perform. CFM is more time‐consuming but is versatile and can be applied to a wider range of metal surfaces than SED, for example brass surfaces which have been coated by a lacquer.  相似文献   
864.
865.
The American War on Drugs has been a long and protracted battle. On the front lines are local, state and federal drug enforcement officers who are tasked with pursuing drug users and dealers. Empirically, officers’ attitudes about the laws they uphold have been shown to impact how aggressively they enforce those laws and the discretion they employ. Although there is a well established body of literature which documents the importance of discretionary dynamics in many areas of law enforcement, we know almost nothing about narcotics officers’ attitudes toward drugs and drug enforcement. Hence, we are unaware of extremely important variables that almost certainly impact and influence front line drug officers. This study fills that gap by examining the survey responses of over 1,000 drug interdiction officers at all levels of law enforcement, measuring their attitudes toward various drugs and the relative harm they incur, along with existing and proposed policies and strategies. The results are discussed in terms of their enforcement and policy implications.  相似文献   
866.
Sheriff’s offices are an integral component of the public health emergency preparedness and response system in the USA. During a public health emergency or disaster, sheriff’s offices need to communicate with people affected by the event. Sheriff’s office websites are logical sources for information about disaster preparedness and response efforts. No prior research evaluates emergency preparedness and response resources available through sheriff’s office websites. The current research is a national study of sheriff’s office websites to assess the availability of information relating to emergency preparedness and response. A content analysis of 2590 sheriff’s office website homepages was conducted to determine the presence or absence of nine communications elements important to people seeking information during an emergency or disaster. We found that 71.9% of sheriff’s office website homepages include links to agency services and programs, but only 6.5% provide links to emergency preparedness information. The findings of the study are useful to assess emergency preparedness and the amount of response information available, as well as to identify opportunities to improve sheriff’s office website homepages.  相似文献   
867.
The diagnostic criteria for posttraumatic stress disorder (PTSD) were substantially revised for Diagnostic and Statistical Manual of Mental Disorders—5th edition (DSM-5). This in turn necessitated revision of DSM-correspondent assessment measures of PTSD. We describe the various changes to the PTSD diagnostic criteria and the corresponding changes to National Center for PTSD measures. We also discuss the implications of the new criteria for assessment of trauma exposure and PTSD. Although the DSM-5 version of PTSD departs significantly in some respects from previous versions, we conclude that there is fundamental continuity with the original DSM-III conceptualization of PTSD as a chronic, debilitating mental disorder that develops in response to catastrophic life events.  相似文献   
868.
869.
870.
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