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   1190篇
  免费   54篇
各国政治   34篇
工人农民   40篇
世界政治   94篇
外交国际关系   501篇
法律   367篇
中国政治   7篇
政治理论   198篇
综合类   3篇
  2023年   10篇
  2022年   7篇
  2021年   5篇
  2020年   23篇
  2019年   28篇
  2018年   47篇
  2017年   54篇
  2016年   34篇
  2015年   27篇
  2014年   64篇
  2013年   132篇
  2012年   88篇
  2011年   97篇
  2010年   69篇
  2009年   83篇
  2008年   63篇
  2007年   56篇
  2006年   45篇
  2005年   53篇
  2004年   53篇
  2003年   57篇
  2002年   50篇
  2001年   14篇
  2000年   8篇
  1999年   9篇
  1998年   6篇
  1997年   5篇
  1996年   3篇
  1995年   7篇
  1994年   4篇
  1993年   8篇
  1992年   4篇
  1991年   2篇
  1990年   1篇
  1989年   2篇
  1988年   4篇
  1987年   1篇
  1986年   2篇
  1984年   4篇
  1983年   2篇
  1980年   1篇
  1978年   2篇
  1977年   2篇
  1976年   1篇
  1975年   1篇
  1974年   2篇
  1973年   1篇
  1971年   3篇
排序方式: 共有1244条查询结果,搜索用时 509 毫秒
1.
This study describes the performance of handheld Raman devices for determining whether suspect pharmaceutical tablets declared to contain controlled substances were consistent with authentic (CWA) or not consistent with authentic (NCWA) tablets using a simple, rapid, field-friendly method capable of being used by nonexperts. Twenty-five authentic products and 84 known NCWA tablets were examined using three “parent” devices for a total of 327 analyses. On average, the parent devices yielded a true pass rate of 100%, a true fail rate of 98.4%, a false pass rate of 1.6%, and a false fail rate of 0%. The methods/libraries were then transferred to 13 identical “daughter” devices, which were used to examine 10 suspect finished dosage forms in duplicate (six known NCWA tablets and four authentic tablets) for a total of 260 measurements. On average, the daughter devices had a true pass rate of 100%, a true fail rate of 95.5%, a false pass rate of 4.5%, and a false fail rate of 0.0%. These data demonstrate that the parent–daughter electronic transfer method was successful, which permits the ability to develop methods in the laboratory that can be seamlessly pushed out to field devices. The methods can then be used to (i) prioritize samples for additional testing using other more time-consuming laboratory-based techniques needed to detect and quantify active ingredients and (ii) help support the interdiction of dangerous tablets at ports of entry, thereby preventing them from reaching the supply chain.  相似文献   
2.
A simple, quick, selective, sensitive, and effective field-friendly method capable of being used by nonexperts has been developed for detecting mitragynine in Mitragyna speciosa (kratom) using surface-enhanced Raman spectroscopy (SERS). Over 100 samples and blanks (known to be either positive or negative for the presence of mitragynine) were examined in duplicate using five identical handheld Raman spectrometers, which provided a data set of over 1,000 examinations. Based on the results of these analyses, the method yielded a true-positive rate of 99.3%, a true-negative rate of 97.9%, a false-positive rate of 2.1%, and a false-negative rate of 0.7%. The average minimum detectable concentration (Cm) of mitragynine that reproducibly yielded a match for one of the library spectra on all five instruments was determined to be 342 ng/mL (ppb). This Cm value is a conservative estimate considering that the extraction process was not fully optimized by this study, which was not necessary since the Cm value achieved was well below typical mitragynine concentrations in kratom (1.3–2.3%). The method is ideal (i) for prioritizing samples for additional testing using other more time-consuming laboratory-based techniques needed to detect and quantify mitragynine and (ii) for field use at international mail facility (IMF) satellite laboratories to help interdict kratom and prevent this dangerous product from reaching the U.S. supply chain.  相似文献   
3.
Hannah  Adam  Baekkeskov  Erik 《Policy Sciences》2020,53(3):437-452
Policy Sciences - Recent scholarship posits that ambiguous (‘polysemic’) ideas are effective for coalition building between diverse stakeholders: their capacity to be interpreted...  相似文献   
4.
Scholars have long sought to explain the overrepresentation of lawyers in Congress. This article draws on a wealth of data to explore the causes and consequences of this representational imbalance. While lawyers enter politics at higher rates, self-selection at best provides a partial explanation. Conditional on running, lawyers win at twice the rate of candidates from other backgrounds. Contrary to prevailing theories in the literature, voters do not reward candidates with backgrounds in law. Rather, lawyers win because of a sizable competitive advantage in early fundraising, owing in large part to their professional networks. This study has important implications for who runs for office, who wins, and the demographic composition of Congress. It also identifies an underexplored mechanism by which the US system of campaign finance sustains deep representational imbalances.  相似文献   
5.
The global defense industrial sector is a remarkably accurate indicator of the distribution of power in the post-Cold War international system. However, the defense industrial sector as a policy tool has received relatively little scrutiny, even though it not only reflects the international order, but also provides the United States with the ability to influence the foreign policy behavior of other states. The defense industrial sector is a powerful, if undervalued, diplomatic tool in the United States’ political arsenal.  相似文献   
6.
Democratization has lately received new rounds of criticism from antidemocrats on both the right and the left. As the prevalence of democracy throughout the world has surpassed that of dictatorship and other forms of undemocratic government, nostalgia for authoritarianism has blurred the realities of the depredations of dictatorship. Increasingly, the new antidemocrats suggest that the problems of democracy require nondemocratic solutions. But while all democracies will necessarily fall short of their ideal, the solution lies within democratic traditions. The challenge is to motivate future generations to improve on existing democracy, not to replace democratic structures with a system that is simpler, more comfortable, and less demanding of those who live under it.  相似文献   
7.
8.
The most ferocious debates are about whether the United States should be described as imperial, but in practice other countries also try to influence other countries’ domestic policies, to propagate their visions, to exert power and to stabilize areas beyond their borders that are perceived as a source of threats. While in the 1990s the winners of globalization were seen as small open states, since the turn of the millennium big powers appear to be gaining because of their ability to project political power: the United States, but also China, Russia, India, and Brazil. This makes for a greater instability and leads to the formulation of theories of realism or neo-realism. The essay concludes with an examination of alternatives to empire and the neo-imperial vision, in particular the importance of elaboration of common or shared values in helping to build a safer and more peaceful international order.  相似文献   
9.
10.
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