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   892篇
  免费   38篇
各国政治   51篇
工人农民   57篇
世界政治   94篇
外交国际关系   37篇
法律   536篇
中国政治   3篇
政治理论   138篇
综合类   14篇
  2023年   6篇
  2022年   6篇
  2021年   16篇
  2020年   23篇
  2019年   17篇
  2018年   40篇
  2017年   50篇
  2016年   51篇
  2015年   32篇
  2014年   36篇
  2013年   124篇
  2012年   46篇
  2011年   27篇
  2010年   19篇
  2009年   22篇
  2008年   33篇
  2007年   43篇
  2006年   36篇
  2005年   26篇
  2004年   38篇
  2003年   29篇
  2002年   35篇
  2001年   25篇
  2000年   15篇
  1999年   10篇
  1998年   3篇
  1997年   8篇
  1996年   8篇
  1995年   3篇
  1993年   5篇
  1992年   4篇
  1991年   7篇
  1990年   7篇
  1989年   7篇
  1988年   5篇
  1987年   4篇
  1984年   4篇
  1983年   6篇
  1981年   3篇
  1980年   2篇
  1979年   4篇
  1978年   2篇
  1977年   3篇
  1976年   2篇
  1975年   2篇
  1974年   2篇
  1973年   7篇
  1972年   8篇
  1971年   10篇
  1966年   2篇
排序方式: 共有930条查询结果,搜索用时 15 毫秒
211.
In this paper, we develop a two-region model of crime spatial displacement. For high crime regions, the crime rate in one locality is negatively influenced by the crime rate of the other. The magnitude of the displacement depends on the distance between the two regions and on their relative size. For given sized neighbors, a closer distance implies greater displacement. When one region is larger, relative to the other, this increases the displacement, holding distance fixed. Examples show that the displacement from the treated to the adjacent areas can be small, if the relative size of the former is small. Nonetheless, the displacement can be large for other nearby areas, provided that the treated region is relatively big. Neglecting this result can cause an upward bias at the estimated impact of a policy. We also analyze the consequences for the design of public policies.  相似文献   
212.
Using a temporal approach dividing the reform process into two periods, this article explains how both Brazil and the United States were slow to respond to AIDS. However, Brazil eventually outpaced the United States in its response due to international rather than democratic pressures. Since the early 1990s, Brazil's success has been attributed to "strategic internationalization": the concomitant acceptance and rejection of global pressure for institutional change and antiretroviral treatment, respectively. The formation of tripartite partnerships among donors, AIDS officials, and nongovernmental organizations has allowed Brazil to avoid foreign aid dependency, while generating ongoing incentives for influential AIDS officials to incessantly pressure Congress for additional funding. Given the heightened international media attention, concern about Brazil's reputation has contributed to a high level of political commitment. By contrast, the United States' more isolationist relationship with the international community, its focus on leading the global financing of AIDS efforts, and the absence of tripartite partnerships have prevented political leaders from adequately responding to the ongoing urban AIDS crisis. Thus, Brazil shows that strategically working with the international health community for domestic rather than international influence is vital for a sustained and effective response to AIDS.  相似文献   
213.
214.
An increasing number of developing and emerging economies have adopted an inflation targeting framework for monetary policy during the last two decades. This article investigates the politics of inflation targeting by focusing on the case of Brazil. I argue that the decision to implement an inflation targeting system in 1999 did not only reflect the concerns of political leaders with maintaining electoral support and external credibility. In addition, the choice of this new policy approach was informed by a shift in the technical consensus among Brazilian economists about the most effective way to tame inflationary pressures in a context of high capital mobility. The shift to inflation targeting thus reflected a process of social learning among technical elites, facilitated not only by the failure of the previous policy but also by the successful experience of other inflation targeting countries. Moreover, the evidence presented here suggests that, as the first country to adopt inflation targets in the context of an IMF-supported program, Brazil became a test case and a natural experiment for the redefinition of IMF conditionality and surveillance mechanisms. The paper thus sheds light on a process of reciprocal learning, whereby the IMF not only contributed to collective learning but also learned from the Brazilian case, subsequently becoming an active promoter of inflation targeting among developing countries.  相似文献   
215.
The three Rio Conventions—the United Nations Framework Convention on Climate Change, the Convention on Biological Diversity, and the United Nations Convention to Combat Desertification—face the challenge to create synergies at different levels. The objective of this article is to describe how we have assessed synergies between the Rio Conventions at the project level in the forest sector. Since the complexity of the decision problem is high, we adopted the Multicriteria Decision Aid approach, which can provide a broad insight into the decision problem and find a compromise solution to a problem with multidimensional and conflicting criteria including social, economic and environmental features. The ELECTRE TRI model was used for assessing synergies at the project level, and has been a useful tool to quantify the performance of afforestation and reforestation projects into three categories (synergistic, reasonably synergistic, and not synergistic). For the first time, afforestation and reforestation projects have been assessed in a comprehensive way through decision criteria that reflect global and local interests using a non-compensatory multicriteria method.  相似文献   
216.
Sex estimation is the first step for biological profile reconstruction of an unknown skeleton (archaeological or contemporary) and consequently for positive identification of skeletal remains recovered from forensic settings. Several tools have been developed using different osseous structures. With the intention to provide an objective method comparison, we reported the analysis of three different methods (visual, metric and geometric morphometrics) for sex assessment of the greater sciatic notch. One hundred and thirty pelvic bones (45.4% females and 54.6% males) from the National Autonomous University of Mexico Skeletal Collection pertaining to the contemporary Mexican population were analyzed. We used the ROC-analysis to test between desired false positive thresholds (1-specificity) and expected true positive rates (sensitivity) in order to predict the best approach to sex assessment. The comparison of the area under the ROC-curves shows significant differences among visual and metric methods. At the same time, the analysis suggested that higher morphological variation among the sexes is independent of the methodological approach. The results indicate that the metric (angle), with a high percent of indeterminate cases (34.6%), and visual, with 26.2% of the cases allocated as intermediate cases, were poorly accurate; we cannot recommend these techniques for sexing an unknown specimen. On the other hand, the geometric morphometrics approach improves sex estimation in 82.3% of correctly classified individuals with more than 95% of posterior probability. In addition to the method comparison, the major sexual variation of the greater sciatic notch was determined to be located on its posterior border.  相似文献   
217.
A liquid chromatography-tandem mass spectrometry (LC-MSMS) target screening in 50mg hair was developed and fully validated for 35 analytes (Δ9-tetrahidrocannabinol (THC), morphine, 6-acetylmorphine, codeine, methadone, fentanyl, amphetamine, methamphetamine, 3,4-methylenedioxyamphetamine, 3,4-methylenedioxymethamphetamine, benzoylecgonine, cocaine, lysergic acid diethylamide, ketamine, scopolamine, alprazolam, bromazepam, clonazepam, diazepam, flunitrazepam, 7-aminoflunitrazepam, lorazepam, lormetazepam, nordiazepam, oxazepam, tetrazepam, triazolam, zolpidem, zopiclone, amitriptyline, citalopram, clomipramine, fluoxetine, paroxetine and venlafaxine). Hair decontamination was performed with dichloromethane, and incubation in 2 mL of acetonitrile at 50°C overnight. Extraction procedure was performed in 2 steps, first liquid-liquid extraction, hexane:ethyl acetate (55:45, v:v) at pH 9, followed by solid-phase extraction (Strata-X cartridges). Chromatographic separation was performed in AtlantisT3 (2.1 mm × 100 mm, 3 μm) column, acetonitrile and ammonium formate pH 3 as mobile phase, and 32 min total run time. One transition per analyte was monitored in MRM mode. To confirm a positive result, a second injection monitoring 2 transitions was performed. The method was specific (no endogenous interferences, n=9); LOD was 0.2-50 pg/mg and LOQ 0.5-100 pg/mg; linearity ranged from 0.5-100 to 2000-20,000 pg/mg; imprecision <15%; analytical recovery 85-115%; extraction efficiency 4.1-85.6%; and process efficiency 2.5-207.7%; 27 analytes showed ion suppression (up to -86.2%), 4 ion enhancement (up to 647.1%), and 4 no matrix effect; compounds showed good stability 24-48 h in autosampler. The method was applied to 17 forensic cases. In conclusion, a sensitive and specific target screening of 35 analytes in 50mg hair, including drugs of abuse (THC, cocaine, opiates, amphetamines) and medicines (benzodiazepines, antidepressants) was developed and validated, achieving lower cut-offs than Society of Hair Testing recommendations.  相似文献   
218.
Methanol is a potent neurotoxic substance that causes severe metabolic acidosis and serious neurological disorders. Most of the cases are accidental exposures to drinking beverages contaminated with methanol. There are few articles reporting pure methanol intoxication; however, it is well known that small quantities of pure methanol causes blindness and death, the minimum lethal dose being 50-100 ml.A case report is presented of a 67-year-old woman, who committed suicide by ingestion of 500 ml of absolute methanol. Despite symptomatic and supportive intensive care, the woman died 23 h after hospital admission due to metabolic acidosis and multiple organ dysfunction syndrome. A complete medico-legal autopsy was performed. Grossly, there was complete detachment of the oesophagus mucosa and brownish discolouration of the gastric mucosa. Histological findings showed diffuse haemorrhagic necrosis of the stomach mucosa and intense acute inflammatory infiltration of the lamina propria. To our knowledge, this is the first autopsy report of such severe digestive injuries. A discussion and review of the recent literature on the subject are given.  相似文献   
219.
The purpose of this study is to clarify the chronology of different stages of dental development, according to Demirjian, in a sample of Spanish children, which will enable us to build a database that will be used as a reference in regard to the dental development of individuals of our socio-geographic environment. In the same studied sample, a calculation of the dental age according to Demirjian was carried out. This study was conducted in a final sample consisting of 1010 orthopantograms, corresponding to Spanish children (485 boys and 525 girls) ages 2-16. Comparing the age of onset of the different stages among the children, evidence was found that girls had an earlier general development than boys. These differences were only statistically significant in teeth and concrete stages. The canine teeth revealed greater gender dimorphism, with significant differences in all stages compared with the upper canines. The method proposed by Demirjian for dental age calculation resulted in a significant overestimation of dental age in relation to the chronological age in boys (average of 0.87 years) and girls (average of 0.55 years). Data from this study may be used as reference for dental maturity, as well as a standard for estimating age in Spanish children.  相似文献   
220.
One crucial element for the evolution of cooperation may be the sensitivity to others?? efforts and pay-offs in comparison with one??s own costs and gains. If an individual responds to a disadvantageous reward distribution, then it would likely increase its relative fitness compared with those who do not (Brosnan & de Waal, Nature 428:140, 2004). Recent experimental research indicates that sensitivity toward unequal reward distribution is not a uniquely human trait; non-human primates react to inequity if they witness a conspecific that obtains a more attractive reward for the same effort. However, primates are not the only species that cooperate and thus would benefit from inequity aversion. Canids also frequently cooperate with group members (e.g., wolves, wild dogs, etc.) or humans (domestic dogs), allowing for the possibility that they also are sensitive to the reward distribution. We report the findings of two studies of dogs?? responses to inequity and the social factors that mediate such responses. In the first study, we investigated whether domestic dogs showed a response to the inequity of rewards received for the same action in pairs of familiar dogs. We found that dogs showed significant behavioral differences when tested without food rewards when in the presence of a rewarded partner compared to the baseline and asocial control situations. This indicated that the presence of a rewarded partner matters (Range, Horn, Virányi, & Huber, Proc Natl Acad Sci USA 106(1):340?C345, 2009). In contrast to primates, dogs did not react to differences in the quality of food or effort. In the second study, we analyzed whether individual (motivational or personality) characteristics determined the response of each subject to unequal reward distributions or whether the subject??s responses depended on the specific relationship they had with its partner. We found that individual motivation and the quality of the relationship influenced the dogs?? performance in test conditions, but that these factors varied across the control and reward inequity conditions. Overall, our results suggest that inequity aversion in dogs is conditional on their and their partner??s rewards. Whether inequity aversion is based on the same mechanisms in both humans and non-human primates is still unclear.  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