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   3688篇
  免费   98篇
各国政治   336篇
工人农民   88篇
世界政治   383篇
外交国际关系   271篇
法律   1415篇
中国共产党   1篇
中国政治   27篇
政治理论   1226篇
综合类   39篇
  2023年   11篇
  2022年   16篇
  2021年   35篇
  2020年   69篇
  2019年   65篇
  2018年   107篇
  2017年   131篇
  2016年   126篇
  2015年   81篇
  2014年   99篇
  2013年   623篇
  2012年   95篇
  2011年   105篇
  2010年   93篇
  2009年   125篇
  2008年   164篇
  2007年   155篇
  2006年   110篇
  2005年   112篇
  2004年   115篇
  2003年   92篇
  2002年   106篇
  2001年   89篇
  2000年   79篇
  1999年   76篇
  1998年   64篇
  1997年   57篇
  1996年   48篇
  1995年   58篇
  1994年   48篇
  1993年   46篇
  1992年   31篇
  1991年   52篇
  1990年   30篇
  1989年   47篇
  1988年   34篇
  1987年   39篇
  1986年   52篇
  1985年   20篇
  1984年   25篇
  1983年   31篇
  1982年   34篇
  1981年   19篇
  1980年   28篇
  1979年   23篇
  1978年   22篇
  1977年   16篇
  1976年   16篇
  1974年   21篇
  1973年   9篇
排序方式: 共有3786条查询结果,搜索用时 0 毫秒
211.
An investigation was carried out on the effect of the intake of diazepam and alcohol on simple performance tests. The combined administration of diazepam and alcohol led to an increase of the plasma diazepam concentration as compared to that obtained after diazepam without alcohol. Furthermore, after combined intake of diazepam and alcohol a decrease of performance was observed, that was significantly higher, than the effects obtained after either alcohol or diazepam alone. This impairment was especially noticeable duirng the first hour of the experiment, i.e. until the plateau of the diazepam plasma concentration was reached, while afterwards a correlation between diazepam plasma concentration and impairment of performance could not be established. The relevance of these findings for the interpretation of diazepam plasma concentrations in relation to the impairment of performance are discussed.  相似文献   
212.
Degradation of human DNA extracted from forensic stains is, in most cases, the result of a natural process due to the exposure of the stain samples to the environment. Experiences with degraded DNA from casework samples show that every sample may exhibit different properties in this respect, and that it is difficult to systematically assess the performance of routinely used typing systems for the analysis of degraded DNA samples. Using a batch of artificially degraded DNA with an average fragment size of approx. 200 bp a collaborative exercise was carried out among 38 forensic laboratories from 17 European countries. The results were assessed according to correct allele detection, peak height and balance as well as the occurrence of artefacts. A number of common problems were identified based on these results such as strong peak imbalance in heterozygous genotypes for the larger short tandem repeat (STR) fragments after increased PCR cycle numbers, artefact signals and allelic drop-out. Based on the observations, strategies are discussed to overcome these problems. The strategies include careful balancing of the amount of template DNA and the PCR cycle numbers, the reaction volume and the amount of Taq polymerase. Furthermore, a careful evaluation of the results of the fragment analysis and of automated allele calling is necessary to identify the correct alleles and avoid artefacts.  相似文献   
213.
214.
Der Beitrag geht der Frage nach, wie national unterschiedliche politökonomische Institutionen die Leistungskraft entwickelter Marktwirtschaften beeinflussen und ob institutionelle Komplementaritäten in der Makroökonomie existieren. Der Ansatz der ?Spielarten des Kapitalismus“ behauptet, dass es diese Komplementaritäten gibt und sich die Länder entsprechend dem in den ökonomischen Sphären vorherrschenden Modus der Koordination in klare Gruppen unterscheiden lassen. In dem Artikel werden die Kernaussagen des Ansatzes einer Reihe von empirischen Tests unterzogen, die auf einer zusammenfassenden Analyse einer Reihe von Fallbeispielen beruht, Die empirischen Ergebnisse bestätigen die Annahmen in überzeugender Weise. Dieliberalen undkoordinierten Marktwirtschaften variieren systematisch entsprechend dem relativen Verhältnis zwischen marktförmiger und strategischer Koordination. Institutionelle Komplementaritäten finden sich in beiden Typen, und sie bringen gesamtwirtschaftliche Leistungszuwächse hervor. Abschließend werden die Muster des institutionellen Wandels in den entwickelten politischen Ökonomien analysiert und einige politische Implikationen der Befunde diskutiert.  相似文献   
215.
216.
The purpose of this study was to evaluate the ability of two amphetamine class screening reagents to exclude ephedrine (EPH), pseudoephedrine (PSEPH), and phenylpropanolamine (PPA) from falsely producing positive immunoassay screening results. The study also sought to characterize the prevalence and concentration distributions of EPH, PSEPH, and PPA in samples that produced positive amphetamine screening results. Approximately 27,400 randomly collected human urine samples from Navy and Marine Corps members were simultaneously screened for amphetamines using the DRI and Abuscreen online immunoassays at a cutoff concentration of 500 ng/mL. All samples that screened positive were confirmed for amphetamine (AMP), methamphetamine (MTH), 3,4-Methylenedioxyamphetamine (MDA), 3,4-Methylenedioxymethamphetamine (MDMA), EPH, PSEPH, and PPA by gas chromatography/mass spectrometry (GC/MS). The DRI AMP immunoassay identified 1,104 presumptive amphetamine positive samples, of which only 1.99% confirmed positive for the presence of AMP, MTH, MDA, or MDMA. In contrast, the online AMP reagent identified 317 presumptive amphetamine positives with a confirmation rate for AMP, MTH, MDA, or MDMA of 7.94%. The presence of EPH, PSEPH, or PPA was confirmed in 833 of the 1,104 samples that failed to confirm positive for AMP, MTH, MDA, or MDMA; all of the 833 samples contained PSEPH. When compared to the entire screened sample set, PSEPH was present in approximately 3%, EPH in 0.9%, and PPA in 0.8% of the samples. The results indicate that cross reactivities for EPH, PSEPH, and PPA are greater than reported by the manufacturer of these reagents. The distribution of concentrations indicates that very large concentrations of EPH, PSEPH, and PPA are common.  相似文献   
217.
The eruption and mineralization of third molars are the main criteria for dental age estimation of living people involved in criminal proceedings. Since the development of third molars is usually completed by the age of 19 or 20 years, this feature cannot be used to ascertain whether a person has attained the forensically relevant age of 21 years. This study examined whether the DMFT index or the third molar DFT index could supply reliable information enabling conclusions to be drawn about whether a person has reached the age of 21. To this end, 650 conventional orthopantomograms of German subjects aged 18 to 30 years were evaluated. The DMF index variations considered were found to be unsuitable for determining whether a person is over 21 because they displayed a weak correlation with age and considerable individual scatter. A high indicative value can only be attributed to a third molar DFT index of 4, although this is rarely observed in the relevant age group. An X-ray examination of the medial clavicular epiphyseal cartilage is, therefore, strongly recommended when assessing whether a person has attained 21 years of age.  相似文献   
218.
The second part of the paper on suicides by gunshots to the head in the presence of witnesses focuses on relevant morphological autopsy findings such as entrance site, signs of close range or contact shots, bullet path etc. and also discusses selected aspects of ascertaining gunshot residues. For the identification of the shooter an integral medicolegal assessment of all the facts including the investigation results and the autopsy findings is essential. However, the morphological findings alone do not allow safe diagnosis, as for example in a homicide the temporal region, which was affected in all our cases, may have been deliberately chosen by the perpetrator as a localization typical of suicide. Thus methods to ascertain gunshot residues on the firing hand (by means of adhesive films and the polyvinyl-alcohol collection method--PVAL) are of great practical importance. In seven cases adhesive films and/or the polyvinyl-alcohol collection method were used. In one case the gunshot residues (GSR) were analysed by means of tape lifts and subsequent scanning electron microscopy (SEM). It was found that especially the combined application of topographical (adhesive tape/PVAL) and cumulative (SEM) methods allowed for the doubtless identification of the shooter, thus usually confirming the suicide. By the example of one case it is demonstrated that without the immediate collection of evidence at the scene objective reconstruction of the event becomes impossible. On the basis of the reported cases recommendations are finally given for a differentiated approach in the medicolegal evaluation of alleged witnessed suicide by gunshot (to the head).  相似文献   
219.
220.
In this paper, we describe the development of a device for fuming fingerprints with cyanoacrylate (Super Glue) to enable police tactical units to obtain fingerprint evidence from suspicious packages using a remote-controlled robot. Through a series of initial experiments and preliminary designs, we show that effective cyanoacylate fuming requires sufficient heat, humidity, and airflow. This work led to the development of a final working prototype, called robot accessory for fuming fingerprint evidence (RAFFE), which is currently being field tested by the Calgary Police Service.  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