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   977篇
  免费   55篇
各国政治   70篇
工人农民   84篇
世界政治   102篇
外交国际关系   44篇
法律   513篇
中国政治   7篇
政治理论   208篇
综合类   4篇
  2023年   12篇
  2022年   13篇
  2021年   9篇
  2020年   24篇
  2019年   26篇
  2018年   64篇
  2017年   64篇
  2016年   47篇
  2015年   39篇
  2014年   42篇
  2013年   141篇
  2012年   38篇
  2011年   47篇
  2010年   48篇
  2009年   25篇
  2008年   37篇
  2007年   50篇
  2006年   29篇
  2005年   26篇
  2004年   25篇
  2003年   29篇
  2002年   17篇
  2001年   27篇
  2000年   37篇
  1999年   24篇
  1998年   8篇
  1997年   11篇
  1996年   2篇
  1995年   2篇
  1994年   4篇
  1993年   2篇
  1992年   2篇
  1991年   2篇
  1990年   3篇
  1989年   8篇
  1988年   5篇
  1987年   2篇
  1986年   2篇
  1985年   5篇
  1984年   4篇
  1983年   10篇
  1982年   1篇
  1981年   3篇
  1980年   3篇
  1979年   2篇
  1978年   1篇
  1977年   5篇
  1976年   3篇
  1975年   1篇
  1967年   1篇
排序方式: 共有1032条查询结果,搜索用时 15 毫秒
71.
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   
72.
Sudden unexpected death in an infant caused by or associated with neoplasm is rare. We describe a case of a sudden death in an apparently healthy 3-month-old female, in which the autopsy revealed a multiple type II infantile hepatic hemangioendothelioma (IHE). This uncommon tumor has, untreated, a relatively high mortality rate, mainly due cardiac failure resulting from massive arteriovenous shunts, but the association with sudden infant death is very rare.  相似文献   
73.
74.
Amniotic fluid embolism (AFE), a relatively rare complication in pregnancy, has a high mortality rate. We describe a case of a 38-week pregnant woman with such an embolism leading to almost immediate death after a blunt abdominal trauma inflicted in a motor vehicle accident and probably associated with improper positioning of a seat belt. It has been assumed that the pathophysiology of amniotic fluid embolism is related to an anaphylactoid reaction and that mast cell degranulation indicates this mechanism. Moreover, immunohistochemical antitryptase staining of pulmonary tissue samples in our case revealed mast cell degranulation.  相似文献   
75.
The news media have the potential to act as a powerful influence on the civil litigation system, influencing decision making in particular cases and on the system more generally as media reports influence the decision making of various participants in the system. This paper reviews the research that has examined the relationship between news media reporting and civil litigation and proposes a framework that integrates this work and provides guidance for future research efforts. Specifically, we discuss the nature of media reporting on civil litigation, perceptions of the civil litigation system held by the public and legal actors, and the potential influence of news reporting about civil litigation on the decision making of jurors, judges, civil litigants, and policymakers. Overall, the research suggests that news reporting of civil litigation presents a systematically distorted picture of civil litigation and that this reporting can influence perceptions and outcomes of civil litigation in various ways. However, there are many gaps in the existing research that need to be filled. The proposed organizational scheme helps to identify ways that future research can provide links between the findings of existing research and to identify ways in which this research can be extended to new areas.  相似文献   
76.
Fatty acid ethyl esters (FAEE) can be used as alcohol markers in hair. It was investigated in this study whether this diagnostic method is disturbed by hair care and hair cosmetics. Traces of ethyl myristate, ethyl palmitate, ethyl oleate and ethyl stearate were detected in all of 49 frequently applied hair care products by headspace solid phase microextraction (HS-SPME) and gas chromatography-mass spectrometry (GC-MS). The highest concentration was 0.003% in a hair wax. From experiments with separated hair samples of alcoholics as well as from the evaluation of the FAEE concentrations and the data about hair care of 75 volunteers (alcoholics, social drinkers and teetotalers) follows that usual shampooing, permanent wave, dyeing, bleaching or shading are of minor importance as compared to the drinking amount and other individual features. However, false positive results were found after daily treatment with a hair lotion containing 62.5% ethanol, with a deodorant and with a hair spray. As an explanation, it is assumed that FAEE are formed in the sebum glands also after regular topical application of products with a higher ethanol content.  相似文献   
77.
We develop an empirical estimator directly from an extensive-formcrisis bargaining game with incomplete information and discussits features and limitations. The estimator makes it possibleto draw inferences about states' payoffs from observationaldata on crisis outcomes while remaining faithful to the theorizedstrategic and informational structure. We compare this estimatorto one based on a symmetric information version of the samegame, using the quantal response equilibrium proposed in thiscontext by Signorino (1999, American Political Science Review93:279–298). We then address issues of identificationthat arise in trying to learn about actors' utilities by observingtheir play of a strategic game. In general, a number of identifyingrestrictions are needed in order to pin down the distributionof payoffs and the effects of covariates on those payoffs.  相似文献   
78.
79.
80.
The 4-methylaminorex (4-MAX) is an amphetamine-related psychostimulant drug that has appeared on the clandestine market with a street name of "U4Euh". This compound exists as four stereoisomers, trans-4R,5R, trans-4S,5S, cis-4R,5S and cis-4S,5R, of which the cis forms have been classified as Schedule I substances in the US. The increasing variety of designer drugs has highlighted the importance of detection, identification, and quantitative measurement of these drugs, including 4-MAX, in biological samples. In the present study, the isomers of 4-MAX were detected in urine of rats treated with the drugs by some but not all of the on-site immunoassays tested, mainly as amphetamine or methamphetamine. To facilitate identification of 4-MAX by laboratories specialized in drug analysis, the electron-ionization mass spectrum and TLC data for underivatized 4-MAX using a routine laboratory drug-screening procedure is provided. In addition, a GC/MS method is described for the quantitative determination of cis- and trans-4-MAX as tert-butyldimethylsilyl-derivatives in plasma, urine and tissue.  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