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   824篇
  免费   49篇
各国政治   102篇
工人农民   66篇
世界政治   82篇
外交国际关系   60篇
法律   349篇
中国政治   22篇
政治理论   186篇
综合类   6篇
  2023年   5篇
  2022年   6篇
  2021年   9篇
  2020年   7篇
  2019年   36篇
  2018年   34篇
  2017年   47篇
  2016年   44篇
  2015年   22篇
  2014年   24篇
  2013年   184篇
  2012年   20篇
  2011年   30篇
  2010年   22篇
  2009年   18篇
  2008年   27篇
  2007年   23篇
  2006年   21篇
  2005年   12篇
  2004年   18篇
  2003年   16篇
  2002年   26篇
  2001年   19篇
  2000年   18篇
  1999年   13篇
  1998年   12篇
  1997年   7篇
  1996年   7篇
  1995年   6篇
  1994年   12篇
  1993年   5篇
  1992年   9篇
  1991年   6篇
  1990年   10篇
  1989年   8篇
  1988年   4篇
  1987年   11篇
  1985年   5篇
  1984年   5篇
  1983年   7篇
  1982年   8篇
  1981年   4篇
  1979年   5篇
  1978年   4篇
  1977年   3篇
  1975年   3篇
  1974年   3篇
  1973年   3篇
  1972年   4篇
  1966年   3篇
排序方式: 共有873条查询结果,搜索用时 15 毫秒
101.
A unique longitudinal study of the technical communication patterns of 184 engineers in a high technology research and development laboratory centers in the activities of technology gatekeepers. This two-step flow of technical information follows the literature as well as results from prior studies. Gatekeepers span the organizational boundary in the transfer of technology from outside the laboratory, while facilitating the distribution of technical information to colleagues within the organization. Sociometric data are analyzed over a five-year period with respect to changing organizational structures, new technical assignments and alterations in group composition. Despite these dynamic changes, the data reveal consistent results in gatekeeper identification and technical information flows.  相似文献   
102.
103.
104.
105.
Drug screening through urinalysis is a widely accepted tool for rapid detection of potential drug use at a relatively low cost. It is, therefore, a potentially useful method for detecting and monitoring drug use in a variety of contexts such as the criminal justice system, pre-employment screening and a variety of treatment centers. This article explores the efficacy of two commercially available drug-screening assays: Online KIMS assay (Roche) and EMIT II assays. First, we evaluate the sensitivity and specificity of two immunoassays. A total of 738 urine samples were collected among adult arrestee populations from Chicago, New Orleans and Seattle through the Arrestee Drug Abuse Monitoring (ADAM) program. Partial samples were split within one laboratory and analyzed by both enzymes multiplied immunoassay technique (EMIT) II and kinetic interaction of microparticle in solution (KIMS) assays for a 10-drug panel (amphetamine, barbiturates, benzodiazepines, marijuana, cocaine, methadone, methaqualone, opiate, phencyclidine and propoxyphene). Gas chromatography-mass spectrometry (GC-MS) was used as a confirmation method for all positives from either EMIT II or KIMS for all experiments. Second, the paper examines whether using different testing laboratories plays a role in the final results. The same experiments were repeated at two different testing locations: one in California and one in London and England. Third, the paper studies whether drug testing results vary between two laboratories when each of them had used their own routine screening method: the Forensic Science Service (FSS) at Birmingham, United Kingdom with KIMS assay and Medscreen Limited at London, United Kingdom with EMIT II. In summary, both EMIT II and KIMS assays generate fairly consistent results. The concordance rate against each of the 10 drugs tested is relatively high (97.4-100%). The discrepancies, in most cases, occurred at drug concentrations near the cut-off levels. There were more discrepant results between two laboratories compared to when specimens were analyzed at the same laboratory using two different assays.  相似文献   
106.
OBJECT: The aim of this study was the examination of relationship between the age and the ossification of medial epiphysis of the clavicle referred to CT examination. MATERIALS AND METHODS: Concerning the epiphyseal ossification of the clavicle CT's of 100 patients (50 male and 50 female) between 16 and 25 years (10 patients for each year) were analyzed by three viewers. RESULTS: In the legal relevant age segment (16-25a) we saw a turnover from stage 3 to stage 4 at the age of 21 years. The calculated empiric distribution function showed 95% of stage 4 over 21 years while 75% of the patients with stage 3 were under 21 years. A reconstruction kernel suitable for osseous structures should be used, images should be viewed or presented in a bone window. CONCLUSION: According to these results it can be concluded that a person with stage 4 is probably 21 years or older, while a stage 3 leads to an estimated age under 21 years. On the other hand, a confidence level of 99.67% is not reached. Therefore, CT of the medial epiphysis of the clavicle will only be suitable for age estimation around the age of 21 years, if this relevant statistic obstacle is defeated. Bearing this in mind, further studies are needed to evaluate slice thickness as the most critical parameter.  相似文献   
107.
This study provides an empirical analysis of the effects of advertising and commercial practice on the price and quality of optometrists' services. Data were collected by actually purchasing eye examinations and eyeglasses from optometrists in cities with and without restrictions on advertising and commercial practice. Analysis of the data supports the view that advertising and commercial practice lower prices but do not lower the quality of professional care available in the market. The implications of these findings are discussed.  相似文献   
108.
109.
110.
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