全文获取类型
收费全文 | 1303篇 |
免费 | 75篇 |
专业分类
各国政治 | 73篇 |
工人农民 | 73篇 |
世界政治 | 199篇 |
外交国际关系 | 105篇 |
法律 | 552篇 |
中国政治 | 10篇 |
政治理论 | 359篇 |
综合类 | 7篇 |
出版年
2023年 | 13篇 |
2022年 | 10篇 |
2021年 | 12篇 |
2020年 | 36篇 |
2019年 | 54篇 |
2018年 | 78篇 |
2017年 | 94篇 |
2016年 | 68篇 |
2015年 | 49篇 |
2014年 | 44篇 |
2013年 | 211篇 |
2012年 | 54篇 |
2011年 | 46篇 |
2010年 | 27篇 |
2009年 | 32篇 |
2008年 | 51篇 |
2007年 | 47篇 |
2006年 | 38篇 |
2005年 | 41篇 |
2004年 | 26篇 |
2003年 | 36篇 |
2002年 | 37篇 |
2001年 | 28篇 |
2000年 | 20篇 |
1999年 | 18篇 |
1998年 | 22篇 |
1997年 | 16篇 |
1996年 | 9篇 |
1995年 | 14篇 |
1994年 | 11篇 |
1993年 | 15篇 |
1992年 | 14篇 |
1991年 | 6篇 |
1990年 | 5篇 |
1989年 | 8篇 |
1988年 | 6篇 |
1987年 | 4篇 |
1986年 | 7篇 |
1985年 | 4篇 |
1984年 | 6篇 |
1983年 | 5篇 |
1982年 | 12篇 |
1981年 | 5篇 |
1980年 | 4篇 |
1979年 | 3篇 |
1978年 | 7篇 |
1977年 | 6篇 |
1976年 | 4篇 |
1971年 | 4篇 |
1967年 | 2篇 |
排序方式: 共有1378条查询结果,搜索用时 750 毫秒
1.
Adam Lanzarotta Ph.D. Martin M. Kimani Ph.D. Michael D. Thatcher B.S. John Lynch Ph.D. Moseley Fulcher A.S. Mark R. Witkowski Ph.D. JaCinta S. Batson M.S. 《Journal of forensic sciences》2020,65(4):1274-1279
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.
Palacios Diego Berger Christian Luengo Kanacri Bernadette Paula Veenstra René Dijkstra Jan Kornelis 《Journal of youth and adolescence》2019,48(10):2005-2022
Journal of Youth and Adolescence - How the interplay between peer relationships and behaviors unfolds and how this differs between classrooms is an understudied topic. This study examined whether... 相似文献
3.
Adam Lanzarotta Ph.D. Michael D. Thatcher B.S. Lisa M. Lorenz B.S. JaCinta S. Batson M.S. 《Journal of forensic sciences》2020,65(5):1443-1449
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
4.
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
5.
Adam Bonica 《Legislative Studies Quarterly》2020,45(2):253-289
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
6.
Henk Elffers Jan W. de Keijser Peter J. van Koppen Laurien van Haeringen 《Journal of Experimental Criminology》2007,3(2):163-182
This article reports on a field experiment on the effect of media information on people’s attitudes towards the justice system.
For the duration of a year a Dutch local newspaper took small groups of readers, called ‘newspaper jurors’, to court sessions
of criminal cases and subsequently reported on their experiences and perceptions. Using a quasi-experimental design, we examined
whether an attitude change in the general reader population of this particular local newspaper occurred as a result of the
jury’s newspaper reports. Findings show that, after the treatment interval of 1 year, no attitude change in the general reader
population could be identified that was absent in the control group. 相似文献
7.
Das deutsche Bodenschutzrecht ist angesichts seines geringen Anwendungsbereiches sowie seiner sehr lückenhaften und zudem
vollzugsunfreundlichen Konkretisierung in Grenzwerten h?ufig wenig effektiv. Diese These verfolgt der vorliegende Beitrag
anhand eines besonders wesentlichen, in der politischen, juristischen und naturwissenschaftlichen Debatte bisher kaum beachteten
gesundheits- und umweltrelevanten Faktors: der düngungsbedingten Belastung von B?den durch Uraneintr?ge. Dies verhilft zugleich
zu einer n?heren Bestimmung der konkurrierenden Anwendungsbereiche verschiedener Umweltgesetze. 相似文献
8.
9.
10.