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   1071篇
  免费   64篇
各国政治   59篇
工人农民   148篇
世界政治   95篇
外交国际关系   55篇
法律   551篇
中国政治   14篇
政治理论   207篇
综合类   6篇
  2024年   2篇
  2023年   17篇
  2022年   8篇
  2021年   14篇
  2020年   28篇
  2019年   50篇
  2018年   64篇
  2017年   85篇
  2016年   78篇
  2015年   43篇
  2014年   46篇
  2013年   156篇
  2012年   58篇
  2011年   55篇
  2010年   38篇
  2009年   47篇
  2008年   50篇
  2007年   53篇
  2006年   48篇
  2005年   32篇
  2004年   20篇
  2003年   16篇
  2002年   15篇
  2001年   9篇
  2000年   5篇
  1999年   11篇
  1998年   8篇
  1997年   6篇
  1996年   4篇
  1995年   9篇
  1994年   6篇
  1993年   8篇
  1992年   4篇
  1991年   3篇
  1990年   1篇
  1989年   2篇
  1988年   3篇
  1987年   4篇
  1986年   4篇
  1985年   6篇
  1984年   4篇
  1983年   5篇
  1982年   4篇
  1980年   2篇
  1978年   2篇
  1974年   2篇
排序方式: 共有1135条查询结果,搜索用时 31 毫秒
221.
This column provides a country by country analysis of the latest legal developments, cases and issues relevant to the IT, media and telecommunications' industries in key jurisdictions across the Asia Pacific region. The articles appearing in this column are intended to serve as ‘alerts’ and are not submitted as detailed analyses of cases or developments.  相似文献   
222.
The application of isotopic techniques to investigations requiring the provision of evidence to a Court is limited. The objective of this research was to investigate the application of light stable isotopes and isotope ratio mass spectrometry (IRMS) to solve complex forensic cases by providing a level of discrimination not achievable utilising traditional forensic techniques.Due to the current threat of organic peroxide explosives, such as triacetone triperoxide (TATP), research was undertaken to determine the potential of IRMS to differentiate samples of TATP that had been manufactured utilising different starting materials and/or manufacturing processes. In addition, due to the prevalence of pentaerythritoltetranitrate (PETN) in detonators, detonating cord, and boosters, the potential of the IRMS technique to differentiate PETN samples from different sources was also investigated.Carbon isotope values were measured in fourteen TATP samples, with three definite groups appearing in the initial sample set based on the carbon data alone. Four additional TATP samples (in a second set of samples) were distinguishable utilising the carbon and hydrogen isotopic compositions individually, and also in combination with the oxygen isotope values. The 3D plot of the carbon, oxygen and hydrogen data demonstrated the clear discrimination of the four samples of TATP. The carbon and nitrogen isotope values measured from fifteen PETN samples, allowed samples from different sources to be readily discriminated.This paper demonstrates the successful application of IRMS to the analysis of explosives of forensic interest to assist in discriminating samples from different sources. This research represents a preliminary evaluation of the IRMS technique for the measurement of stable isotope values in TATP and PETN samples, and supports the dedication of resources for a full evaluation of this application in order to achieve Court reportable IRMS results.  相似文献   
223.
An evaluation was undertaken to determine if isotope ratio mass spectrometry (IRMS) could assist in the investigation of complex forensic cases by providing a level of discrimination not achievable utilising traditional forensic techniques. The focus of the research was on ammonium nitrate (AN), a common oxidiser used in improvised explosive mixtures.The potential value of IRMS to attribute Australian AN samples to the manufacturing source was demonstrated through the development of a preliminary AN classification scheme based on nitrogen isotopes. Although the discrimination utilising nitrogen isotopes alone was limited and only relevant to samples from the three Australian manufacturers during the evaluated time period, the classification scheme has potential as an investigative aid.Combining oxygen and hydrogen stable isotope values permitted the differentiation of AN prills from three different Australian manufacturers. Samples from five different overseas sources could be differentiated utilising a combination of the nitrogen, oxygen and hydrogen isotope values. Limited differentiation between Australian and overseas prills was achieved for the samples analysed.The comparison of nitrogen isotope values from intact AN prill samples with those from post-blast AN prill residues highlighted that the nitrogen isotopic composition of the prills was not maintained post-blast; hence, limiting the technique to analysis of un-reacted explosive material.  相似文献   
224.
225.
Five experiments tested the idea that instructing a witness to close their eyes during retrieval might increase retrieval success. In Experiment 1 participants watched a video, before a cued-recall test for which they were either instructed to close their eyes, or received no-instructions. Eye-closure led to an increase in correct cued-recall, with no increase in incorrect responses. Experiments 2-5 sought to test the generality of this effect over variations in study material (video or live interaction), test format (cued- or free-recall) and information modality (visual or auditory details recalled). Overall, eye-closure increased recall of both visual detail and auditory details, with no accompanying increase in recall of false details. Collectively, these data convincingly demonstrate the benefits of eye-closure as an aid to retrieval, and offer insight into why hypnosis, which usually involves eye-closure, may facilitate eyewitness recall.  相似文献   
226.
This study examined the association between sexual relationship power, intimate partner violence, and condom use among African American and Hispanic urban girls. In this sample of 56 sexually active girls, 50% did not use condoms consistently and therefore were at higher risk for acquiring HIV or sexually transmitted diseases (STDs). Teens who experienced more intimate partner violence had a significantly higher likelihood of inconsistent condom use and therefore a greater risk for HIV/STDs. Girls' sense of sexual control in their relationships was not directly associated with inconsistent condom use but was inversely related to verbal and emotional abuse. Interventions aimed at reducing HIV/STD risk for adolescent girls need to address patterns of dominance and control in adolescent relationships as well as multiple forms of partner violence. This suggests the need for multilevel intervention approaches that promote girls' agency and multiple ways to keep girls safe from perpetrators of partner abuse.  相似文献   
227.
The "red zone" usually refers to the first few weeks of the first semester at college, when female students are believed to be at greatest risk for experiencing unwanted sex. We tested this notion using data from a survey study of 207 first-and second-year students (121 women, 84 men) at a small, liberal arts university. Results demonstrated only one significant elevation in incidence rates of first- and second-year women's unwanted sexual experiences (sexual touching, attempted and completed anal, oral, and vaginal sex), between the end of the first month and fall break (mid-October) during the second year at school. Previous research and local information about the relevant behaviors of sorority and fraternity members is discussed in light of these findings to provide heuristic material for further empirical testing. Because risk may involve both temporal and situational factors, systematic collection and dissemination of local data are recommended.  相似文献   
228.
The technique of principal component analysis has been applied to the UV-vis spectra of inks obtained from a wide range of black ballpoint pens available in the UK market. Both the pen ink and material extracted from the ink line on paper have been examined. Here, principal component analysis characterised each spectrum within a group through the numerical loadings attached to the first few principal components. Analysis of the spectra from multiple measurements on the same brand of pen showed excellent reproducibility and clear discrimination between inks that was supported by statistical analysis. Indeed it was possible to discriminate between the pen ink and the ink line from all brands examined in this way, suggesting that the solvent extraction process may have an influence on these results. For the complete set of 25 pens, interpretation of the loadings for the first few principal components showed that both the pen inks and the extracted ink lines may be classified in an objective manner and in agreement with the results of parallel thin layer chromatography studies. Within each class almost all inks could be individualised. Further work has shown that principal component analysis may be used to identify a particular ink from a database of reference UV-vis spectra and a strategy for developing this approach is suggested.  相似文献   
229.
Media reports about fatal work accidents in zoos caused by zoo animals seem to appear in increasing numbers all around the world. In many cases the cause of such an accident can only be clarified by a detailed reconstruction of the event in combination with the autopsy results. This applies particularly in cases where no eyewitnesses were present. This report is about the case of a musk ox that killed its keeper, in which the fatal accident could be completely reconstructed.  相似文献   
230.
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