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   7159篇
  免费   477篇
各国政治   334篇
工人农民   221篇
世界政治   467篇
外交国际关系   231篇
法律   5055篇
中国政治   34篇
政治理论   1258篇
综合类   36篇
  2020年   158篇
  2019年   169篇
  2018年   178篇
  2017年   212篇
  2016年   210篇
  2015年   198篇
  2014年   181篇
  2013年   743篇
  2012年   154篇
  2011年   171篇
  2010年   206篇
  2009年   226篇
  2008年   168篇
  2007年   159篇
  2006年   172篇
  2005年   160篇
  2004年   178篇
  2003年   156篇
  2002年   138篇
  2001年   311篇
  2000年   251篇
  1999年   229篇
  1998年   99篇
  1997年   64篇
  1996年   69篇
  1995年   81篇
  1994年   86篇
  1993年   89篇
  1992年   152篇
  1991年   157篇
  1990年   145篇
  1989年   155篇
  1988年   122篇
  1987年   138篇
  1986年   124篇
  1985年   132篇
  1984年   102篇
  1983年   116篇
  1982年   83篇
  1981年   78篇
  1980年   55篇
  1979年   108篇
  1978年   69篇
  1977年   58篇
  1976年   50篇
  1975年   48篇
  1974年   55篇
  1973年   55篇
  1972年   44篇
  1968年   40篇
排序方式: 共有7636条查询结果,搜索用时 15 毫秒
961.
962.
Mugshot searches fail because the witness must be shown too many photos. Current methods to reduce the number rely too heavily on verbal reports of individual features. This research reports three tests of a new system that augments the presently used tools by having the witness choose photos that are subjectively similar to the target. Each photo thus chosen increases the ranking of every photo in the album that is similar to it, as determined by a similarity network in which the album photos are embedded. Because the ranking of the target itself is usually thus increased, it is soon displayed. The tests used familiar targets, an incidental one, and unfamiliar videoed ones. From 76% to 84% of the “witnesses” reached the target, having viewed 2.4 to 8.5 times fewer photos than they would have had they simply leafed through photos as is traditionally done.  相似文献   
963.
964.
The different statements concerning the slope and intercept of the regression line and the 95% limits of confidence are the reason that potassium in vitreous humor is not used (at least in Germany) as an aid in estimating the time of death. The relationship between the concentration of potassium and the time of death is mainly influenced by antemortem electrolyte imbalances caused by disease and/or duration of terminal episode. The influence of terminal episode is best identified by its duration (Adelson et al., J. Forensic Sci., 8 (1963) 503–514). In order to have a method suitable for every case and to be as precise as possible we looked therefore for parameters in vitreous humor which were stable postmortem and indicating antemortem electrolyte imbalance. Urea is such a parameter, being stable postmortem (Coe, Am. J. Clin. Pathol., 51 (1969) 741–750) and useful as a marker of antemortem electrolyte imbalance. Our investigations on potassium in vitreous humor, including sudden and hospital deaths after chronic lingering disease, revealed 95% limits of confidence of ±34 h up to 120 h postmortem. Reviewing only cases with urea less than 100 mg/dl the 95% limits of confidence could be reduced to ±22 h. Considering the duration of terminal episode (<6 h) the precision was ±20 h. In this way our modified procedure is suitable for every case with the resulting precision of estimation being determined only by the duration of the terminal episode and urea concentration.  相似文献   
965.
966.
The unlabeled antibody (PAP) immunoperoxidase technique was applied to the ABO blood grouping of human scalp hairs. Hair samples were subjected to longitudinal- or cross-sectioning, thus obtaining suitable samples for subsequent immunostaining. The immunostaining was carried out using rabbit anti-A and anti-B sera as the primary antibodies. With this technique, the group-specific staining which is revealed as a dark brown precipitate was clearly observed within the medullae of the hair shaft, and depending on the presence or absence of these precipitates, respective blood groups of unknown hair samples were determined. At the hair root, on the other hand, positive stainings were observed not only in medullary cells but also in some cortical cells of the keratogenous zone. From the present study, it can be safely said that this technique is of practical use for the ABO blood grouping from a minute (less than 3 mm) hair sample.  相似文献   
967.
A case is presented where phentermine, a sympathomimetic amine used as an anorectic drug, is believed to have significantly contributed to the death of an individual in whom other drugs were also found. Blood, urine, and tissue concentrations of phentermine are reported and compared to other cases in the literature.  相似文献   
968.
969.
Empirical studies frequently have reported an association between age at release from prison and recidivism. For criminal justice decision-makers who wish to consider this knowledge in making prosecutorial, sentencing, or parole decisions, the magnitude of that association must be established while controlling for the effects of other variables known to be associated with recidivism (e.g., prior criminal record). This research addresses this issue using data from a large sample of federal prison releasees. The results indicate that recidivism rates do decline with increased age, and that the association is not diminished when statistical control is exercised for the effect of prior criminal record.  相似文献   
970.
The specificity of antisera raised against each of the prostaglandin series 190H E1/E2 and 190H F1 alpha/F2 alpha, produced in males, was evaluated by radioimmunoassay. Further, the ability of these antisera to detect semen specific prostaglandins in mixtures of body fluids was examined. Antisera directed against the 190H E1/E2 series cross-reacted with prostaglandin E1 and marginally with E2. Antisera raised to the 190H F1 alpha/F2 alpha series were, however, highly specific to the semen specific prostaglandins 190H F1 alpha/F2 alpha and 190H E1/E2. It was possible to detect picogramme quantities of contaminating 190H F1 alpha/F2 alpha on vaginal swabs taken up to 72 h after intercourse and on vaginal swabs stored at room temperature for up to 2 years. These prostaglandins were not detected on semen free vaginal swabs, in faecal material, saliva, urine or in a sample of human milk (stain). A limited study of casework material is also described. Detection of the 190H F series, as a group, has considerable potential in the identification of human semen at picogramme levels, eliminating the need for alternative chemical tests and extensive microscopic examination.  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