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   1238篇
  免费   67篇
各国政治   71篇
工人农民   59篇
世界政治   91篇
外交国际关系   103篇
法律   682篇
中国政治   10篇
政治理论   279篇
综合类   10篇
  2023年   18篇
  2022年   16篇
  2021年   15篇
  2020年   36篇
  2019年   47篇
  2018年   47篇
  2017年   60篇
  2016年   66篇
  2015年   37篇
  2014年   58篇
  2013年   172篇
  2012年   59篇
  2011年   40篇
  2010年   38篇
  2009年   44篇
  2008年   46篇
  2007年   63篇
  2006年   44篇
  2005年   53篇
  2004年   39篇
  2003年   38篇
  2002年   42篇
  2001年   19篇
  2000年   18篇
  1999年   23篇
  1998年   13篇
  1997年   9篇
  1996年   7篇
  1995年   14篇
  1994年   9篇
  1993年   3篇
  1992年   20篇
  1991年   7篇
  1990年   6篇
  1989年   10篇
  1988年   8篇
  1987年   6篇
  1986年   7篇
  1985年   6篇
  1984年   3篇
  1983年   7篇
  1982年   4篇
  1981年   2篇
  1980年   4篇
  1975年   3篇
  1973年   2篇
  1969年   3篇
  1966年   3篇
  1962年   1篇
  1955年   1篇
排序方式: 共有1305条查询结果,搜索用时 46 毫秒
11.
A gas chromatographic (GC) fingerprint method, based on the presence or absence of six congeners, was developed for illicit cocaine samples. The fingerprint utilizes the relative abundances of these congeners towards each other, disregarding cocaine as the main constituent, and can be expressed numerically or graphically in the form of pictograms for rapid visual comparison. The method can be applied directly to a solution of the sample in chloroform, without previous workup procedures. More than 70 unrelated samples were analyzed and a great variation was observed in the parameter composition. On the other hand, a remarkable similarity could be seen between related samples. The GC fingerprint method may be considered an important contribution for sample comparison, as is exemplified by a subdivision of the analyzed samples in different categories, based on the number and types of congeners found.  相似文献   
12.
13.
Despite its difficulties and inconsistencies in framing those practices andconducts recently unveiled by the press and judicial investigations whichhave caused considerable public discontent, the penal definition ofcorruption still highlights an interesting conceptual diversity across spaceand time that should not be overlooked. Most official discussions about andreferences to corruption and its volume are still framed within these hardparameters. It is, therefore, important to look at the intricacies ofcorruption as a crime in order to understand the virtues and failures ofnational repressive efforts. While crime statistics are of limited use for itsmeasurement, they can nevertheless help to interpret the way corruptionhas been treated through repressive instruments cross-nationally over aperiod of time.The aim of this paper is to assess the dynamics of the various processes ofsetting and revising penal standards to the conduct of office holders and theresults observable from the application of corruption and related offencesacross countries with different legal traditions.  相似文献   
14.
15.
The impact of high temperatures (24 to 39 degrees C) and low to moderately high humidities (20 to 70%) on the applicability of TLC systems for drug identification was studied during a 6 month climatologic cycle in Burkina Faso (West Africa). In general, the Rf values as observed on the plates were found to be substantially affected as compared with values obtained at temperate climates. Some TLC systems were more affected than others and the largest deviations of up to 30 Rf units were at low humidities. Tropical conditions also had a negative effect on the reproducibility of Rf values. However, when an Rf-correction procedure was applied, using reference mixtures of known drugs on each plate, accuracy as well as reproducibility of the resulting Rfc values were drastically improved and data thus corrected were found to be compatible with existing TLC data bases developed under moderate climatological conditions. The impact of high to extremely high humidities (70 to 100%) remains to be investigated.  相似文献   
16.
测定了痢疾杆菌福氏 2a 30 1株与喹喏酮类药物耐药性相关的 gyrA基因和 parC基因的序列 ,并对其环丙沙星耐药诱变株的 gyrA和 parC基因喹喏酮类药物耐药性决定区 (QRDR)序列进行了测定分析。结果表明 ,痢疾杆菌福氏 2a 30 1株 gyrA和 parC基因分别为 2 6 2 5bp和2 2 5 6bp ,环丙沙星诱导的耐药菌 gyrA基因QRDR(2 4 5bp)发生氨基酸残基 6 9 Ala→Val和 87 Tyr→Asp改变 ,parC基因QRDR(2 37b)发生氨基酸残基 79 Ala→Asp、84 Ala→Glu和 85 Pro→Ala改变。这一研究结果对认识痢疾杆菌喹喏酮类药物耐药性的分子机理具有重要意义  相似文献   
17.
18.
Studies of restorative justice programs continue to provide a review of restorative justice practice and impact. While this body of research is growing, many questions remain regarding the impact of restorative justice in reducing crime. By relying on individual and community-level data, the present study examined how offense type and poverty level influenced program completion and recidivism among juveniles in a restorative justice program. This study also examined the relationship between program completion and recidivism. Findings revealed that status offenders in the restorative justice program were more likely to complete the program and less likely to recidivate than status offenders in the comparison group. In addition, property offenders in the restorative justice program were less likely to recidivate than property offenders in the comparison group. Poverty level at the community-level had a significant influence in both program completion and recidivism.  相似文献   
19.
This paper describes the analytical methodology for the determination of MDMA, MDA, MDEA and MBDB in oral fluid. After a liquid–liquid extraction, the analysis was carried out by high performance liquid chromatography (HPLC), with fluorescence detection. The detector wavelength was fixed at 285 nm for excitation and 320 nm for emission. The mobile phase, a mixture of phosphate buffer (pH = 5) and acetonitrile (75:25), and the column, Kromasil 100 C8 5 μm 250 mm × 4.6 mm, allowed good separation of the compounds in an isocratic mode in only 10 min. The method was validated and showed good limits of detection (2 ng/mL) and quantitation (10 ng/mL) for all the amphetamine derivatives. No interfering substances were detected. A stability study of these compounds in oral fluid stored at three different temperatures (−18, 4 and 20 °C) over 10 weeks was conducted, showing a time-dependent degradation of the four compounds.  相似文献   
20.
Drug trade is widely seen as a phenomenon rather new to the Netherlands. However, at the beginning of the 20th century the Dutch pharmaceutical industries were already extensively involved in the production of both opiates and cocaine, and they went on exporting large quantities of these drugs after the Opium Act (1919) took force. Until the 1960s, arrests were not at all common, and these largely affected minority groups like Chinese opium smokers and black marijuana users. Since then, drug control efforts have increased by leaps and bounds. At first, cannabis was the main target; then the focus turned to heroin, and that was later joined by cocaine. This paper traces the history of the drug trade and drug control in the Netherlands, with emphasis on their development in Amsterdam. The conclusion is reached that, in spite of drastic changes in both drug trade and drug control, certain ideologies, constructs and strategies have remained remarkably stable.  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