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   11386篇
  免费   313篇
各国政治   466篇
工人农民   403篇
世界政治   784篇
外交国际关系   345篇
法律   7036篇
中国政治   76篇
政治理论   2497篇
综合类   92篇
  2020年   108篇
  2019年   179篇
  2018年   210篇
  2017年   243篇
  2016年   240篇
  2015年   176篇
  2014年   201篇
  2013年   1109篇
  2012年   236篇
  2011年   285篇
  2010年   232篇
  2009年   289篇
  2008年   299篇
  2007年   286篇
  2006年   286篇
  2005年   266篇
  2004年   265篇
  2003年   271篇
  2002年   257篇
  2001年   445篇
  2000年   382篇
  1999年   308篇
  1998年   175篇
  1997年   138篇
  1996年   146篇
  1995年   146篇
  1994年   144篇
  1993年   149篇
  1992年   243篇
  1991年   261篇
  1990年   249篇
  1989年   261篇
  1988年   235篇
  1987年   234篇
  1986年   268篇
  1985年   264篇
  1984年   238篇
  1983年   220篇
  1982年   156篇
  1981年   133篇
  1980年   114篇
  1979年   154篇
  1978年   90篇
  1977年   113篇
  1976年   97篇
  1975年   74篇
  1974年   90篇
  1973年   84篇
  1972年   81篇
  1971年   70篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
72.
73.
Deoxyribonucleic acid (DNA) typing of ribosomal ribonucleic acid (rRNA) genes was performed with a polymerase chain reaction (PCR) assay for species identification. A variable region of the 28S ribosomal RNA gene was amplified with primers complementary to flanking sequences phylogenetically well conserved. The products of twelve animal DNAs (human, Japanese monkey, dog, cattle, pig, cat, rabbit, mouse, rat, chicken, frog, and fish) were separated by polyacrylamide gel electrophoresis, each revealing a few bands ranging from 150 to 100 base pairs. The band patterns obtained from each DNA sample differed in number and size, which indicates the applicability of the method to species identification. Samples containing either as little as 1 pg of DNA or degraded DNA of 0.2 to 0.5 kb in length were able to give detectable bands. Postmortem human tissue DNAs were tested as an example. They showed a pattern identical to the human control one, which was distinct from those of the other animals examined.  相似文献   
74.
75.
The authors examine the characteristics of threatening and otherwise inappropriate communications sent to members of the U.S. Congress by a sample of 86 subjects, 20 of whom threatened assassination. We quote excerpts from these letters and provide quantitative data on such variables as the volume, duration, form, and appearance of such communications; the enclosures; the subjects' perceived relationships to the recipients; the thematic content of the communications; and the messages and threats communicated. Comparisons between 43 subjects who pursued encounters with members of Congress and 43 who did not revealed 17 factors associated with such pursuit. In this population, threateners were significantly less likely to pursue an encounter than inappropriate letter writers who did not threaten, regardless of the type of threat or the harm threatened. Inappropriate letters to members of Congress are compared with those directed to Hollywood celebrities. Mentally disordered persons writing to public figures often mention and sometimes threaten public figures other than those to whom the letters are addressed, which raises important issues regarding notification of endangered third parties and the sharing of information among protective agencies.  相似文献   
76.
Bioaerosol data is often used in cases of building mold infestation alleging damage or adverse health effects upon occupants, despite the lack of consistent sampling and analytical protocols and numerical health-based standards. The most fundamental problem in these scenarios is defining a “significant” difference between a suspect indoor environment and the reference environment, regardless of the type of sampling and analysis utilized. Data interpretation focused upon differences in absolute numerical concentrations of fungi is subject to wide differences in expert opinion. On the other hand, an objective quantification of differences can be expressed in terms of probability and better meets criteria established in evidentiary rules.  相似文献   
77.
Toxicologic findings in the USS Iowa disaster.   总被引:5,自引:0,他引:5  
The toxicologic results from the 47 victims of the explosion on the USS Iowa are presented. Good correlation between carboxyhemoglobin saturations and cause of death was found. There were no correlations between blood cyanide concentrations and causes of death. Volatile analysis suggested postmortem ethanol production rather than antemortem ethanol ingestion. No drugs except nicotine were detected in any of the victims.  相似文献   
78.
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   
79.
In this study, a new method was developed for the impurity profiling of illicit MDMA tablets. The extraction efficiency, linearity, repeatability and reproducibility of the method were evaluated. Eighty two MDMA tablets coming from presumed unrelated large seizures in 2004 (n >500 tablets) were analyzed by gas chromatography mass spectrometry (GC-MS) in order to assess the discrimination power of the method. The latter was found to be practical, robust, relatively easy to perform, highly discriminative and yielding good chromatography. In addition, some new impurities were detected and identified. Their chemical structures and mass spectra are reported.  相似文献   
80.
The role of the state is changing under the impact of, for example, globalization. The changes have been variously understood as the new public management (NPM), the hollowing–out of the state and the new governance. This special issue of Public Administration explores the changing role of the state in advanced industrial democracies. It focuses on the puzzle of why states respond differently to common trends.
This introductory article has three aims. First, we provide a brief review of the existing literature on public sector reform to show that our approach is distinctive. We argue that the existing literature does not explore the ways in which governmental traditions shape reform. Second, we outline an interpretive approach to the analysis of public sector reform built on the notions of beliefs, traditions, dilemmas and narratives. We provide brief illustrations of these ideas drawn from the individual country articles. Finally, we outline the ground covered by all the chapters but we do not summarize and compare their experiences of reform. That task is reserved for the concluding article.  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