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   20375篇
  免费   1341篇
各国政治   992篇
工人农民   920篇
世界政治   1339篇
外交国际关系   733篇
法律   13723篇
中国共产党   9篇
中国政治   124篇
政治理论   3754篇
综合类   122篇
  2023年   96篇
  2022年   85篇
  2021年   124篇
  2020年   509篇
  2019年   532篇
  2018年   703篇
  2017年   734篇
  2016年   812篇
  2015年   607篇
  2014年   623篇
  2013年   2135篇
  2012年   612篇
  2011年   620篇
  2010年   636篇
  2009年   683篇
  2008年   653篇
  2007年   666篇
  2006年   653篇
  2005年   539篇
  2004年   538篇
  2003年   436篇
  2002年   500篇
  2001年   742篇
  2000年   656篇
  1999年   520篇
  1998年   275篇
  1997年   195篇
  1996年   215篇
  1995年   215篇
  1994年   192篇
  1993年   190篇
  1992年   325篇
  1991年   339篇
  1990年   318篇
  1989年   298篇
  1988年   323篇
  1987年   277篇
  1986年   339篇
  1985年   342篇
  1984年   260篇
  1983年   239篇
  1982年   192篇
  1981年   172篇
  1980年   157篇
  1979年   232篇
  1978年   124篇
  1977年   98篇
  1975年   96篇
  1974年   128篇
  1972年   83篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
22.
23.
24.
25.
This study aimed to expand the scope of previous research by assessing the effectiveness of soot-removal techniques on glass from petrol-bomb debris using methods of 1% and 2% sodium hydroxide (NaOH) solutions, ultrasonic bath and vacuum suction. Of particular interest were the 1% and 2% NaOH solutions applied to the soot-covered surfaces. Petrol bombs containing petrol or a 50:50 mix of petrol and motor oil were exploded and the debris was collected for analysis. Favourable results were found to varying degrees using each of the soot-removal methods with the 1% and 2% NaOH wash solutions, being the most useful. The 2% NaOH solution also proved successful as a soak to loosen and remove heavy contamination of soot and accelerants without damaging the finger mark beneath. This study also found that recovery of finger marks in blood from beneath soot using the 2% NaOH solution was possible. Finger marks were also applied to glass bottles with plastic adhesive labels, and providing the fire damage is not too great marks were also retrievable. Results from this study lead to the conclusion that the NaOH wash solution is ideally suited for soot removal to reveal latent and blood-contaminated marks both within the laboratory and at crime scenes.  相似文献   
26.
27.
The lungs of 79 children who had died between the ages of 1 week and 2 years old were histologically examined. 59 of these children could be categorized as cases of Sudden Infant Death because of the history and postmortem findings. In the remaining 20 cases a definite cause of death could be established. This is the same collective on which the histological investigations of the lymphatic tissue has been carried out. Morphological changes which are typical for a virus pneumonia were found in a substantially higher frequency in the cases of Sudden Infant Death than in the control cases. The validity of these findings and their possible significance for the cause of death are discussed.  相似文献   
28.
29.
30.
Fibres used in forensic casework suffer from a disadvantage common to other forms of trace evidence--it is not possible to state with absolute certainty that they originate from a specific source. Target fibre studies, population studies and research on 'blocks of colour' have effectively demonstrated the polymorphism of textile fibres (particularly man-made ones) and have shown that when a fibre is believed to have a specific putative source, the chance that it has originated from a different source purely by coincidence is extremely remote. A study by Houck MM (Houck MM, Inter-comparison of unrelated fibre evidence. Forensic Science International 2003; 135: 146-149) has shown that no coincidental matching fibres were recovered from items of clothing examined in 20 unrelated crimes. The study involved over two million comparisons. This work goes a step further, and using the example of blue polyester fibres shows that even within a very narrow segment of the whole general fibre population, many examples of a specific colour/type of man-made fibre taken from random sources can be compared and the chance of any two being the same is very low. These studies should help to show the specificity and value of transferred fibres in providing forensic evidence.  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