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   660篇
  免费   17篇
各国政治   35篇
工人农民   14篇
世界政治   46篇
外交国际关系   25篇
法律   476篇
中国政治   6篇
政治理论   70篇
综合类   5篇
  2020年   6篇
  2019年   5篇
  2018年   13篇
  2017年   14篇
  2016年   10篇
  2015年   5篇
  2014年   10篇
  2013年   47篇
  2012年   14篇
  2011年   12篇
  2010年   10篇
  2009年   13篇
  2008年   12篇
  2007年   23篇
  2006年   22篇
  2005年   25篇
  2004年   14篇
  2003年   22篇
  2002年   18篇
  2001年   36篇
  2000年   24篇
  1999年   23篇
  1998年   7篇
  1997年   15篇
  1995年   8篇
  1994年   5篇
  1993年   4篇
  1992年   9篇
  1991年   14篇
  1990年   14篇
  1989年   16篇
  1988年   19篇
  1987年   10篇
  1986年   17篇
  1985年   17篇
  1984年   14篇
  1983年   10篇
  1981年   16篇
  1980年   5篇
  1979年   10篇
  1978年   8篇
  1977年   9篇
  1976年   4篇
  1975年   10篇
  1974年   14篇
  1973年   12篇
  1972年   3篇
  1971年   5篇
  1970年   4篇
  1969年   3篇
排序方式: 共有677条查询结果,搜索用时 359 毫秒
251.
A detailed, correlative, histologic evaluation of postmortem changes in the nasal mucosa of chronic cocaine users has shown characteristic mucosal and arteriolar changes as well as typical perivascular and subepithelial alterations compatible with chronic inflammation. These findings confirm and extend recent reports on the effects of cocaine in the coronary circulation and heart muscle as well as provide a new diagnostic tool to the forensic pathologist who suspects that a decedent has been a long-term cocaine abuser.  相似文献   
252.
The files of 874 fatal traumatic accident victims, aged 12-25 years, examined at the Wayne County Medical Examiner's Office during the period 1978-1988 were reviewed. Postmortem blood alcohol results of individuals who died after less than 15 min of hospitalization were utilized to approximate alcohol levels at the time of the fatal injury. Relationships between types of accidents, sex, age, race, and time of accident were examined. White victims were far more likely to have been drinking than blacks, and the data indicated that underaged drinkers were involved in fatal accidents at lower levels of blood alcohol than their counterparts of legal drinking age. Consistent racial differences in average alcohol levels were not observed, however. Unlike female and black victims, who much less frequently tested positive for alcohol when underage, white male victims 16-21 years of age were just as likely to have been drinking as those aged 21-25. The results of the study show that postmortem blood alcohol level can be used to identify differences in alcohol consumption among groups of accident victims in a major metropolitan area.  相似文献   
253.
254.
255.
256.
A general toxicology unknown case is presented to demonstrate our systematic approach. A 20-year-old male was found dead with multiple suicide notes. Overdose was suspected but substances were not known. Blood alcohol was negative. Urine was analyzed by enzyme-multiplied immunoassay technique and was negative for all drugs assayed. Urine was then extracted with ethyl acetate:hexane (1:1) at pH 10 and back-extracted into 1.0N sulfuric acid. The acidic layer was adjusted to pH 10, and re-extracted with ethyl acetate:hexane (1:1). The residue was analyzed by gas chromatography (GC) on a 3% OV-101 column. It was found to be negative for all commonly screened substances. However, several unknown peaks were observed. Electron impact mass spectra of these unknown peaks were obtained and searched for in our computer library of more than 25000 mass spectra. These unknown peaks were identified as doxylamine and pyrilamine by gas chromatography/mass spectrometry. The base peak and molecular ion for pyrilamine were at m/z 121 and 285, respectively. The base peak for doxylamine was at m/z 58. No molecular ion was observed for doxylamine. Both doxylamine and pyrilamine are antihistamines, but are promoted and used in the management of insomnia. Quantitation was performed on a GC using dexbrompheniramine as an internal standard. Blood concentrations for doxylamine and pyrilamine were 0.7 and 7.0 mg/L, respectively. Concentrations in other tissues were determined. Death was caused by combined doxylamine and pyrilamine intoxication; the manner of death was suicide.  相似文献   
257.
258.
259.
This study investigated the effect of soft tissue and different exposure times on the prediction of burning temperatures of bone when using Fourier transform infrared spectroscopy (FTIR). Ovis aries rib bones were burnt at different temperatures and for varying time intervals. Results of a linear regression analysis indicated that burn temperatures can be predicted with a standard error of ±70°C from defleshed bone spectra. Exposure time does not have a significant impact on prediction accuracy. The presence of soft tissue has a significant impact on heat‐induced changes of the bone matrix in low (<300°C) as well as high temperatures (>800°C), slowing down combustion in the former and accelerating it in the latter (p < 0.05). At medium temperatures, no significant difference was noted. These results provide forensic investigators a new perspective with which to interpret the results of crystallinity measures derived from burnt bone.  相似文献   
260.
Allele distributions for the nine STR loci included in the AmpFlSTR Profiler Plus kit were evaluated in a Thai population of 300 unrelated individuals.  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