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   704篇
  免费   8篇
各国政治   41篇
工人农民   45篇
世界政治   77篇
外交国际关系   39篇
法律   409篇
中国政治   1篇
政治理论   100篇
  2024年   8篇
  2023年   8篇
  2022年   5篇
  2021年   15篇
  2020年   19篇
  2019年   16篇
  2018年   32篇
  2017年   47篇
  2016年   43篇
  2015年   27篇
  2014年   33篇
  2013年   85篇
  2012年   32篇
  2011年   17篇
  2010年   13篇
  2009年   16篇
  2008年   23篇
  2007年   32篇
  2006年   26篇
  2005年   20篇
  2004年   29篇
  2003年   18篇
  2002年   25篇
  2001年   23篇
  2000年   9篇
  1999年   10篇
  1997年   3篇
  1996年   4篇
  1993年   2篇
  1992年   4篇
  1991年   5篇
  1990年   6篇
  1989年   7篇
  1988年   4篇
  1987年   4篇
  1985年   1篇
  1984年   3篇
  1983年   3篇
  1981年   1篇
  1979年   3篇
  1978年   1篇
  1977年   1篇
  1975年   1篇
  1974年   1篇
  1973年   7篇
  1972年   5篇
  1971年   9篇
  1970年   1篇
  1966年   1篇
  1965年   1篇
排序方式: 共有712条查询结果,搜索用时 15 毫秒
201.
We explore a setting where the central bank is offered an incentive scheme by an interest group, in addition to the contract designed by the government. We prove that the inflation bias can be eliminated when principals do not cooperate and have different output or inflation objectives. These conclusions contrast with those of Chortareas and Miller (Public Choice 121:131–155, 2004). The reason is that our analysis takes into account the participation constraints of the central bank. We also show that, if principals cooperate, the inflation bias is eliminated when their output target is different but not when they disagree over the inflation objective.  相似文献   
202.
We explore the role that campaign expenditures play in determining electoral outcomes. We study a two-party contest where campaign funds can affect the preferences of voters regarding the saliency of two political issues. We show that an advantage in campaign resources, a pre-campaign partisan advantage, an advantage on every salient issue, or a combination of these indicators, do not always guarantee electoral victory. By contrast, electoral victory is guaranteed if the sum of the proportions of the electorate supporting a party on every salient issue is greater than a critical value. For that to happen it is necessary (but not sufficient) that the party has an advantage on every salient issue.  相似文献   
203.
204.
205.
206.
207.
208.
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   
209.
The aim of our study was to analyse several serum biochemical markers in order to evaluate the discriminant capacity of trace elements individually and jointly in drowning (seawater drowning and freshwater drowning) and their correlation with age, sex, postmortem interval, time in water and concentrations of the trace elements in the drowning medium. Sixty-seven cases of drowning (53 seawater drownings (SWD); 14 freshwater drownings (FWD) and 73 control cases (other asphyxias, n=44, and other causes of death, n=29) were selected according to the scene, cause and circumstances of death, together with autopsy findings. Serum strontium (Sr), magnesium (Mg), sodium (Na), chloride (Cl), calcium (Ca), iron (Fe), urea, creatinine (Cr) and cardiac Troponine T (cTn-T) were measured in the left ventricle (Lv), right ventricle (Rv) and peripheral blood. Lv-Rv differences for each marker and Sr, Mg, Na, Cl, Ca and Fe concentrations in the drowning medium were determinated. Mean concentrations of Sr, Cl and Mg in both ventricles and peripheral serum and Lv-Rv differences and Ca Lv and Na Rv were significantly higher in cases of drowning than for other causes of death. In SWD, Sr, Mg, Ca, Na and Cl were significantly higher in Lv than in Rv as a result of aspirating water. In contrast, haemodilution is evident from the significantly higher levels of Fe and urea in Rv than in Lv in cases of SWD, and from the higher Mg and Cr levels in Rv in FWD. In the case of SWD, serum levels of Sr are confirmed as the best parameter for diagnosis, although other trace elements may also be useful, such as the serum concentrations of Mg and Cl. In the case of FWD, the joint determination of Sr and other biochemical markers, especially Fe, may increase correct diagnosis.  相似文献   
210.
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