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   5435篇
  免费   253篇
各国政治   378篇
工人农民   191篇
世界政治   591篇
外交国际关系   418篇
法律   2370篇
中国政治   48篇
政治理论   1633篇
综合类   59篇
  2023年   39篇
  2022年   19篇
  2021年   41篇
  2020年   87篇
  2019年   116篇
  2018年   199篇
  2017年   196篇
  2016年   252篇
  2015年   142篇
  2014年   157篇
  2013年   883篇
  2012年   182篇
  2011年   178篇
  2010年   149篇
  2009年   155篇
  2008年   202篇
  2007年   240篇
  2006年   212篇
  2005年   190篇
  2004年   194篇
  2003年   162篇
  2002年   162篇
  2001年   104篇
  2000年   97篇
  1999年   106篇
  1998年   85篇
  1997年   88篇
  1996年   72篇
  1995年   63篇
  1994年   70篇
  1993年   77篇
  1992年   67篇
  1991年   65篇
  1990年   63篇
  1989年   53篇
  1988年   63篇
  1987年   40篇
  1986年   51篇
  1985年   38篇
  1984年   39篇
  1983年   31篇
  1982年   29篇
  1981年   32篇
  1980年   18篇
  1979年   20篇
  1978年   20篇
  1977年   16篇
  1976年   14篇
  1975年   14篇
  1974年   31篇
排序方式: 共有5688条查询结果,搜索用时 15 毫秒
781.
782.
Fourier-transform infrared spectroscopy (FTIR), discriminate analysis, X-ray fluorescence spectrometry (XRF), and stereoscopic microscopy were used to separate black coral forensic evidence items from similarly appearing items manufactured from plastics, bovid keratin, and mangrove wood. In addition, novel observations were made of bromine and iodine relationships in black coral that have not been previously reported.  相似文献   
783.
784.
The purpose of this study was to combine morphoscopic and metric analyses to assess variation in nasal aperture size and shape of black and white South Africans. Thirteen landmarks were digitized from the bony nasal region of 152 crania using an electromechanic instrument for geometric morphometric (general procrustes analysis) and craniometric analyses. Elliptical Fourier analysis was used to assess shape of the nasal aperture via outlines applied through photographs. Both principal component and discriminant function analyses were applied to these statistical methods. Black South Africans were classified 95-96% correctly and white South Africans were classified 91-94% correctly. In a four-way analysis of sex and ancestry, classification accuracy ranged from 56 to 70%. Most misclassifications were between the sexes within each group which suggests an absence of sexual dimorphism. This study found that there is quantifiable variation in shape of the nasal aperture between black and white South African groups using all three statistical methods. In forensic application, standard craniometrics can be used to accurately classify an unknown person.  相似文献   
785.
This study investigates the factors that shape the attitudes of scientists toward starting their own business or working in a private sector firm. The analysis is based on data collected from scientists working in the German Max Planck Society, a research institution devoted to basic science. We find that the scientists’ attractiveness of working in a private sector firm or of starting their own business differ considerably according to their academic discipline and the self-reported commercial potential of their research. The ability to take risks, prior work experience in private firms, and personal experience in cooperating with industry lead to a positive attitude towards switching to private sector employment or entrepreneurship. Strong willingness to freely distribute research findings is related to a low appeal of private sector work.  相似文献   
786.
While a number of studies examine the parenting and social bond causes of low self-control in data obtained in the United States, very few focus on these constructs on data collected in international settings. The resulting gap in the literature is a major one in terms of the understanding of how low self-control potentially develops in other countries. This study tests several parenting and social bond models in an attempt to spur future global research on the concepts that are associated with low self-control. The data were collected from a convenience sample of 414 high school students in a suburb of a large Chinese city. Measures of Gottfredson and Hirschi’s parental variables as well as those of other investigators are included. Additionally, important social bonds such as maternal, school, and peer attachment are also specified. Results indicate that almost all of the parenting and bond measures are significantly associated with the development of low self-control. These findings indicate the possibility that both parenting and relationship factors are potentially important to the development of low self-control in Chinese high school students.  相似文献   
787.
Why do imposed democracies endure and how do policy choices by imposing states affect durability? To study these questions, we formulate expectations linking durability to structural domestic conditions, the level of domestic security in the state into which a polity is imposed, the policies of imposing states, and the regional environment within which an imposed democracy is nested. We use event history to test our expectations on a sample of democracies imposed during the twentieth century. We find that relatively immutable, structural conditions, such as ethnic cleavages, economic development, and prior democratic experience strongly influence the durability of imposed democracies. While some policy choices made by imposing states can impact the survival of imposed democracy, they do so only modestly relative to the environment in which a democracy is imposed.  相似文献   
788.
The fallibility of forensic science consultation is an ongoing and major justice concern. Prospective peer‐reviewed forensic consultation has over 10 years of application in American criminal and civil courts, adapting from the traditional oversight of teaching hospitals, rules of evidence and discovery, conventions of testimony of expert witnesses, and attorneys' overall trial strategy. In systematizing heightened oversight, this process ensures greater accountability in forensic science consultation. The integration of peer reviewers' complementary expertise and experience enhances the sophistication and overall quality of assessment. Forensic examination frequently involves the interface of different specialties. Multidisciplinary peer review augments expert proficiency with that of professional peers having different vantage points from relevant scientific disciplines. This approach ensures greater sophistication of a case inquiry, built‐in accountability, and streamlined processes when multiple experts are necessitated. Here, the authors present examples of several cases and the primary and secondary benefits of this collaborative, rigorous, cross‐disciplinary exercise.  相似文献   
789.
Gas chromatography–mass spectrometry (GC–MS) data of ignitable liquids in the Ignitable Liquids Reference Collection (ILRC) database were processed to obtain 445 total ion spectra (TIS), that is, average mass spectra across the chromatographic profile. Hierarchical cluster analysis, an unsupervised learning technique, was applied to find features useful for classification of ignitable liquids. A combination of the correlation distance and average linkage was utilized for grouping ignitable liquids with similar chemical composition. This study evaluated whether hierarchical cluster analysis of the TIS would cluster together ignitable liquids of the same ASTM class assignment, as designated in the ILRC database. The ignitable liquids clustered based on their chemical composition, and the ignitable liquids within each cluster were predominantly from one ASTM E1618‐11 class. These results reinforce use of the TIS as a tool to aid in forensic fire debris analysis.  相似文献   
790.
Gang membership is a robust correlate of homicide offending and victimization, but little is known about the association between gang status and various abnormal forms of homicide (e.g., multiple-victim homicide, sexual homicide, and abduction homicide). The current study utilized data from a large sample of 618 male convicted murderers to empirically examine gang status and diverse forms of homicide perpetration. Gang-involved offenders were nearly three times as likely to commit a normal homicide characterized as a single-victim murder. However, gang members were 64 % less likely to perpetrate multiple-victim murder. In other models, gang status reduced the likelihood of sexual homicide by 75 % and reduced the likelihood of abduction homicide by 56 %. These findings present an anomaly in the gang-homicide literature, and suggestions for additional research are offered.  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