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   49篇
  免费   2篇
各国政治   1篇
工人农民   5篇
世界政治   2篇
法律   23篇
政治理论   20篇
  2020年   2篇
  2017年   5篇
  2015年   3篇
  2014年   4篇
  2013年   10篇
  2011年   1篇
  2010年   1篇
  2009年   3篇
  2007年   4篇
  2006年   3篇
  2005年   2篇
  2003年   1篇
  2002年   2篇
  2001年   1篇
  1998年   1篇
  1996年   1篇
  1995年   1篇
  1993年   1篇
  1987年   2篇
  1984年   1篇
  1977年   1篇
  1966年   1篇
排序方式: 共有51条查询结果,搜索用时 31 毫秒
41.
Reference material was synthesised for 21 substances that are frequently present as synthetic impurities, i.e. by-products, in illicitly produced amphetamine. Each of these substances is a typical by-product for at least one of the three approaches most often used to synthesise amphetamine, namely, the Leuckart, the reductive amination of benzyl methyl ketone, and the nitrostyrene routes. A large body of data on the substances was recorded, including the following: mass spectra, ultraviolet spectra, Fourier transform infrared spectra, infrared spectra in gas phase, and 1H NMR and 13C NMR spectra.  相似文献   
42.
The present study focused on the stability of 22 amphetamine impurities dissolved in six organic solvents: isooctane, toluene, ethanol, dichloromethane, ethyl acetate, and diethyl ether. The aim was to find the most inert, and thereby most suitable, solvent for amphetamine profiling. Mixtures of the impurities were prepared in the different solvents, and changes in the concentrations of the individual compounds over-time were monitored by gas chromatographic analysis after 0, 4, 12, 24, 48, and 96 h. Isooctane and toluene provided the most inert conditions, although, a few of the impurities were insufficiently stable in these two solvents. The present experiments were performed as a part of the development of a harmonized method for profiling of amphetamine. The results can be used to support the choice of organic solvents for sample preparation. They also provide information about the stability of the impurities that are found in profiles of illicit amphetamine. This is essential due to the fact, that unstable compounds can have a negative influence on the comparison of profiles.  相似文献   
43.
44.
One of the more striking features of the Black Lives Matter movement against racialized police brutality has been the focus on violence inflicted on “black bodies.” On one hand, the language of “black bodies,” as opposed to simply “black people” or “black personhood,” makes the issue of racial violence more visceral and immediate to white audiences otherwise indisposed to perceive black pain as a moral problem. On the other hand, it represents a theoretical challenge to dominant understandings of pain, suffering, and individuality based on liberal subjectivity. Exemplifying both of these aspects, Ta-Nehisi Coates’s recent work, Between the World and Me, provides a deep philosophical reflection on the moral and political problem of “black disembodiment.” This article tracks the theme of disembodiment in Coates’s book by foregrounding the role that feminist theories of embodiment play in his exploration of the contemporary black condition in America.  相似文献   
45.
46.
47.
Amphetamine samples were analysed by gas chromatography-mass spectrometry (GC-MS), and the peak areas of 33 target compounds were transformed by applying various pretreatment techniques. The objective was to optimise the ability of a number of distance metrics to establish links between samples of amphetamine originating from the same batch (henceforth referred to as linked distances). Furthermore, partial least squares discriminant analysis (PLS-DA) was used to evaluate the effects of various pretreatment methods on separation of amphetamine batches synthesised by the Leuckart reaction, reductive amination of benzyl methyl ketone, and the nitrostyrene route. The most efficient way to pretreat GC-MS data varied for the different distance metrics, although best results were obtained when data were normalised to the sum of peak areas, and either the fourth root or a logarithm was applied to the normalised data. When pretreating normalised data by fourth root transformation, Pearson correlation was the distance metric that was most successful at finding linked samples. Normalisation and the use of fourth root also represented the best method of pretreating data when employing PLS-DA to separate samples synthesised by different routes. To achieve a faster and more user-friendly procedure for evaluating chromatograms, experiments were performed in which the number of target compounds used to compare samples was reduced. The effect of each compound that was removed was studied by applying PLS-DA and by using Pearson correlation to calculate linked distances as well as unlinked distances (between samples from different batches of amphetamine). Considering both links between samples from the same batch and separation of samples synthesised by different routes, the best results were obtained with the data set comprising 26 compounds. Finally, it was found that the profiling method developed in this work was superior to an existing technique with respect to separating linked and unlinked distances.  相似文献   
48.
French–German resistance to the US war against Iraq marked a high point in the two countries' political alignment. It was followed by French proposals for even closer integration. Yet French and German policies and priorities differ in a number of fields. Prominent among these is the EU, where Germany has long worked for a reduction in EU spending and a redistribution of votes among the member countries. After reaching a compromise on these issues, co-operation with France on foreign and security policy has grown particularly close. This has affected Germany's relations with Central and Eastern Europe and with the US, areas where Germany traditionally pursued policies different from France. At the end of the second period of the Red–Green government, Germany's national interests have been redefined as a result of the relationship with France.  相似文献   
49.
Market Power Europe (MPE) constitutes an important contribution to the literature on the global role and actorness of the EU. In order to develop MPE as a theory, this contribution provides an assessment of how Russia, the USA and China have converged towards three EU trade policies in 2013. The analysis finds that MPE fails to account for important dynamics related to externalization in the three cases. In order to improve MPE analytically, the article suggests that MPE should include three intervening variables to account for the EU’s ability to externalize its policies and act as MPE in practice.  相似文献   
50.
Presentation order of ID and Alibi evidence was manipulated for undergraduate participants who conducted a simulated police investigation. Experiment 1 found a recency effect when an eyewitness rejected the investigator’s suspect. Experiment 2 also examined order effects, exploring how participant–investigators evaluated alibi information in addition to eyewitness ID information. When investigators saw the witness identify the suspect but also received a strong alibi for that suspect a recency effect occurred, such that whichever piece of information occurred at the end of the procedure had the strongest impact on investigators. Thus, type of evidence and evidence order both had a dramatic influence on participant–investigators’ decisions.  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