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   117篇
  免费   2篇
各国政治   4篇
工人农民   3篇
世界政治   11篇
外交国际关系   5篇
法律   70篇
政治理论   15篇
综合类   11篇
  2021年   2篇
  2019年   4篇
  2018年   1篇
  2017年   1篇
  2016年   5篇
  2015年   1篇
  2014年   1篇
  2013年   19篇
  2012年   5篇
  2011年   10篇
  2010年   7篇
  2009年   8篇
  2008年   6篇
  2007年   5篇
  2006年   5篇
  2005年   6篇
  2004年   5篇
  2003年   5篇
  2002年   1篇
  2000年   1篇
  1998年   2篇
  1997年   1篇
  1993年   2篇
  1992年   1篇
  1991年   3篇
  1990年   2篇
  1987年   1篇
  1985年   1篇
  1984年   1篇
  1981年   1篇
  1979年   1篇
  1978年   2篇
  1976年   1篇
  1974年   1篇
  1972年   1篇
排序方式: 共有119条查询结果,搜索用时 31 毫秒
11.
12.
13.
This paper argues that standard regulatory policies might be inadequate and may even introduce perverse effects when applied to hybrid organizational forms. Using the case of the “certifying system” adopted for several French agricultural products as a benchmark for the discussion, with particular insights provided by the label chicken case, the paper emphasizes the tight coordination process required by the characteristics of the transactions at stake as well as by the necessity to send adequate signals to consumers. However, unadapted regulations tend to misinterpret the resulting contractual arrangement as collusion. This interpretation is challenged here: The form adopted achieves a high degree of efficiency and reduces transaction costs without reducing competition. We conclude that a new approach to regulations may be required, combining two criteria: contestability and remediability.  相似文献   
14.
15.
Forensic analysis of bicomponent fibers using infrared chemical imaging   总被引:2,自引:0,他引:2  
The application of infrared chemical imaging to the analysis of bicomponent fibers was evaluated. Eleven nominally bicomponent fibers were examined either side-on or in cross-section. In six of the 11 samples, infrared chemical imaging was able to spatially resolve two spectroscopically distinct regions when the fibers were examined side-on. As well as yielding characteristic infrared spectra of each component, the technique also provided images that clearly illustrated the side-by-side configuration of these components in the fiber. In one case it was possible to prepare and image a cross-section of the fiber, but in general the preparation of fiber cross-sections proved very difficult. In five of the 11 samples, the infrared spectra could be used to identify the overall chemical composition of the fibers, according to a published classification scheme, but the fiber components could not be spatially resolved. Difficulties that are inherent to conventional "single-point" infrared spectroscopy, such as interference fringing and sloping baselines, particularly when analyzing acrylic type fibers, were also encountered in the infrared chemical image analysis of bicomponent fibers. A number of infrared sampling techniques were investigated to overcome these problems, and recommendations for the best sampling technique are given. Chemical imaging results were compared with those obtained using conventional fiber microscopy techniques.  相似文献   
16.
This article describes the use of an anti-Stokes luminescent material (upconverter), yttrium vanadate doped with ytterbium and erbium (YVO(4):Er,Yb), for the development of latent fingermarks on a range of non-porous surfaces. Anti-Stokes luminescent materials emit light at shorter wavelengths than the excitation wavelength. This property is unusual in both natural and artificial materials commonly found as exhibits in forensic science casework. As a result, fingermark detection techniques based on anti-Stokes luminescence are potentially extremely sensitive and selective. Latent fingermarks on non-luminescent and inherently luminescent substrates, including Australian polymer banknotes (a well-known 'difficult' surface), were developed with YVO(4):Er,Yb by dry powder and wet powder techniques. The effectiveness of YVO(4):Er,Yb for fingermark detection was compared with that of cyanoacrylate fuming and of sodium yttrium tetrafluoride doped with ytterbium and erbium (NaYF(4):Er,Yb). The results illustrate some benefit of luminescent up-converting phosphors over traditional luminescence techniques for the detection of latent fingermarks.  相似文献   
17.
The present study aimed at providing data to assess the secondary transfer of organic gunshot residues (OGSR). Three scenarios were evaluated in controlled conditions, namely displacing a firearm from point A to point B, a simple handshake and an arrest involving handcuffing on the ground. Specimens were collected from the firearm, the hands of the shooter and the non-shooter undergoing the secondary transfer in order to compare the amounts detected.Secondary transfer was observed for the three scenarios, but to a different extent. It was found that displacing a firearm resulted in secondary transfer in <50% of the experiments. The firearm also had an influence, as contrary to the pistol, no secondary OGSR were detected using the revolver. Shaking the hand of the shooter also transferred OGSR to the non-shooter's hand. In that case, the amount of OGSR was generally higher on the shooter than on the non-shooter. Finally, the largest secondary transfer was observed after the arrest with handcuffing with positive results in all cases using the pistol. In that scenario, the amounts on the shooter and the non-shooter were in the same range.This study highlights that the secondary transfer must be taken into account in the interpretation of OGSR. Indeed, an individual's hands might be contaminated by handling a firearm or having physical contact with a shooter.  相似文献   
18.
19.
The recent report of the National Research Council of the US National Academies “Strengthening Forensic Science in the United States: a Path Forward” found evidence that the level of scientific development and evaluation varies substantially among the forensic science disciplines. In this paper the status of trace evidence will be reviewed from an international perspective with particular reference to case studies. The paper will argue that the trace evidence discipline needs to learn from past experience and that serious coordinated action is required at an international level if trace evidence is to continue to meet the standards expected of forensic science in the future. The paper concludes that it is vital that trace evidence remains a key component of forensic investigation due to its important role in addressing the ‘what happened’ question.  相似文献   
20.
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