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   5250篇
  免费   293篇
  国内免费   1篇
各国政治   377篇
工人农民   19篇
世界政治   594篇
外交国际关系   908篇
法律   1646篇
中国共产党   601篇
中国政治   777篇
政治理论   230篇
综合类   392篇
  2023年   33篇
  2022年   39篇
  2021年   32篇
  2020年   46篇
  2019年   67篇
  2018年   76篇
  2016年   38篇
  2015年   46篇
  2014年   210篇
  2013年   150篇
  2012年   285篇
  2011年   298篇
  2010年   217篇
  2009年   172篇
  2008年   216篇
  2007年   249篇
  2006年   279篇
  2005年   225篇
  2004年   208篇
  2003年   236篇
  2002年   209篇
  2001年   153篇
  2000年   145篇
  1999年   105篇
  1998年   96篇
  1997年   95篇
  1996年   82篇
  1995年   88篇
  1994年   100篇
  1993年   58篇
  1992年   51篇
  1991年   68篇
  1990年   63篇
  1989年   72篇
  1988年   96篇
  1987年   88篇
  1986年   88篇
  1985年   95篇
  1984年   90篇
  1983年   86篇
  1982年   60篇
  1981年   62篇
  1980年   75篇
  1979年   37篇
  1977年   17篇
  1964年   23篇
  1962年   19篇
  1961年   17篇
  1960年   17篇
  1959年   17篇
排序方式: 共有5544条查询结果,搜索用时 0 毫秒
241.
A total of 137 urine samples and 46 serum samples, corresponding to 154 self-confessed designer drugs consumers in Ibiza island, were analyzed for the presence of designer drugs: amphetamine and amphetamine derivatives (methamphetamine, methylenedioxymethamphetamine (MDMA), methylenedioxyethylamphetamine (MDEA), methylenedioxyamphetamine (MDA), p-methoxymethylamphetamine (PMMA), p-methoxyamphetamine (PMA), etc.), ketamine and gamma-hydroxybutyric acid. Among this population, coming both from the forensic clinic and from the emergency room of a hospital, a total of 99 cases were found positive for some designer drug. This study shows the prevalence of methylenedioxymethamphetamine (MDMA) among designer drug users, sole or in association with other drugs. Also, the mixture of MDMA with other designer drugs, ethanol and/or cocaine is shown to be more likely to produce toxic symptoms requiring clinical attendance in a hospital emergency room. These findings along with the consumption history, the concentrations of drugs and metabolites in urine and serum and the toxicological significance for the interpretation of some MDMA metabolites such as 4-hydroxy-3-methoxymethamphetamine (HMMA) are discussed in this study.  相似文献   
242.
Downstairs falls frequently occur within domestic environments and are mainly associated with elderly and intoxicated individuals, often feature multiple injuries on various parts of the body. In most cases it is not possible to determine the cause of the fall and/or death solely by means of external examination. In this retrospective study, which covers a period of 11 years, all cases of death which included a fall downstairs in their case history, were collected from the Forensic Institutes of the Universities of Bonn and Greifswald, Germany. Falls downstairs made up to 2% (166 cases) of all postmortem examinations carried out within this period. Interestingly, almost double of the amount of such falls applied to males as to females. The primary cause of death was cranio-cerebral trauma and the vast majority of skull injuries associated with falls downstairs were found above 'the hat brim line'. Injuries were also often found on several other parts of the body at once. Nineteen of the 116 examined individuals exhibited agonal injuries. In these cases, postmortem examination revealed pre-existing disease or intoxication to be the cause of death and thus, cause of the fall. The injury pattern only allows a tendency towards vital or agonal incident as a conclusion.  相似文献   
243.
回顾和总结铁路五次大提速的实践和经验,我认为,其中很重要的一条,就是全路形成了一种颇具特色的思维方式--铁路"提速思维"。所谓铁路"提速思维",是指在铁路大提速过程中形成并运用的、贯穿大提速全过程的一系列思维方法的总和。"提速思维"是一种战略思维、宏观思维,是一种辩证思维、理性思维,它由若干种具体的思维方法所组成。 一是"抓住主要矛盾"的思维方法 毛泽东同志指  相似文献   
244.
We investigated tissue distribution of lidocaine in 33 patients after endotracheal intubation with Xylocaine jelly that contains 2% lidocaine hydrochloride. Blood levels of monoethylglycinexylidide (MEGX), an active metabolite of lidocaine, were also determined. Five patients (Group A) were alive on arrival and six patients (Group B) resumed heartbeats after cardiopulmonary resuscitation (CPR). The survival times for Groups A and B ranged from 3 to 72 h. The remaining 22 patients (Group C) did not survive cardiopulmonary arrest on arrival (CPAOA). Systemic distribution of lidocaine was measured in nine patients from Group C. The liver-to-kidney lidocaine ratios and cerebrum-to-cerebrospinal fluid lidocaine ratios were: Group A, 0.1-0.7 and 1.4-3.6, respectively; Group B, 0.2-0.8 and 1.2-2.3, respectively; Group C, 0.1-17 and 0.2-1.0, respectively. MEGX was detected in all blood samples from Group A and only two samples from Group B. No MEGX was detected in samples from Group C. Our results indicate that the absorption of tracheal lidocaine during natural circulation results in a cerebrum-to-cerebrospinal fluid lidocaine ratio of 1.2 or more, whereas absorption during artificial circulation by cardiac massage gives a ratio of 1.0 or less. The cerebrum-to-cerebrospinal fluid lidocaine ratio may be a more useful index to estimate circulatory dynamics of patients during CPR than the liver-to-kidney lidocaine ratio. MEGX was not a useful parameter for monitoring circulatory changes during cardiac massage.  相似文献   
245.
246.
Frequency of analytical characteristics is best estimated on glass recovered at random. However, as such data were not available to us, we decided to use control windows for this estimation. In order to use such a database, one has to establish that the recovered fragment comes from a window. Therefore, elemental analysis was used both for classification and discrimination of glass fragments. Several articles have been published on the subject, but most methods alter the glass sample. The use of non destructive energy dispersive X-ray microfluorescence (microXRF) for the analysis of small glass fragments has been evaluated in this context. The refractive index (RI) has also been measured in order to evaluate the complementarity of techniques. Classification of fragments has been achieved using Fisher's linear discriminant analysis (LDA) and neural networks (NN). Discrimination was based on Hotelling's T2 test. Only pairs that were not differentiated by RI followed by the Welch test were studied. The results show that neural network and linear discriminant analysis using qualitative and semi-quantitative data establishes a classification of glass specimens with a high degree of reliability. For discrimination, 119 windows collected from crime scene were compared: using RI it was possible to distinguish 6892 pairs. Out of 129 remaining pairs, 112 were distinguished by microXRF.  相似文献   
247.
Evaluation of links in heroin seizures   总被引:4,自引:0,他引:4  
  相似文献   
248.
The extraction of impurities from illegally produced 3,4-methylenedioxymethamphetamine (MDMA) has been studied in order to optimize the parameters. Two different MDMA samples were used. Particular attention was paid to the influence of the pH, the evaporation step, and the sample storage. The method used was an extraction of impurities by diethyl ether from a buffer solution at pH 11.5, followed by gas chromatography (GC) mass spectrometric (MS) analyses after a dryness concentration under monitored conditions of the ethereal extract. Repeat extractions of the same sample gave an average relative standard deviation (RSD) of less than 8.5% within day and less than 10.5% between days.  相似文献   
249.
In animal experiments and in cell culture, chronic morphine treatment has been followed by "up-regulation" as well as "down-regulation" of the mu-opioid receptor (OR) number. The present postmortem morphometric study of morphine-related fatalities of drug-addicts (n=13, 20-35 years old, with blood unconjugated morphine levels from 27.1 ng/ml to 458 ng/ml, m.v. 198.5 ng/ml) versus a non-addicted control group (n=13, 10-44 years old) was intended to examine, whether chronic opiate exposure affects the numerical density of mu-OR expressing neurons in the human neocortex (areas 11, 24 and 25 according to Brodmann). For the immunohistochemical procedure, vibratome sections (100 microm) were incubated with a monoclonal antibody against the mu-OR, diluted 1:100, and immunolabelled sites were visualized using an immunoperoxidase protocol. The numerical densities of OR immunoreactive neuronal profiles and Nissl-stained central profiles were assessed morphometrically (camera lucida-drawings). In both groups, the anti-mu-OR-immunoreactivity was mainly localized in pyramidal neurons of layers (L) II/III and V and in multiform neurons of L VI. In the areas 24 and 25, the density of the immunoreactive neuronal profiles did not display a significant difference between the two examined groups. In the area 11, however, the number of immunolabelled neuronal profiles amounted to 2777+/-206 mm(3) in the drug-related fatalities and to 2320+/-124 mm(3) in the control group and thus was significantly increased.  相似文献   
250.
We provide a short overview on some current issues in the fields of forensic genetics and ancient DNA (aDNA) analysis. We discuss about the existence of the possible points of contact between the two disciplines, in terms of open problems and the inherent approach to their solution. We mainly focus on the problem of results authentication, its theoretical and technical aspects.  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