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   145篇
  免费   5篇
各国政治   5篇
工人农民   19篇
世界政治   4篇
外交国际关系   11篇
法律   71篇
中国政治   1篇
政治理论   39篇
  2023年   2篇
  2022年   4篇
  2021年   2篇
  2020年   5篇
  2019年   5篇
  2018年   4篇
  2017年   4篇
  2016年   10篇
  2015年   3篇
  2014年   4篇
  2013年   12篇
  2012年   4篇
  2011年   4篇
  2010年   2篇
  2009年   3篇
  2008年   5篇
  2007年   7篇
  2006年   3篇
  2005年   4篇
  2004年   1篇
  2003年   6篇
  2002年   7篇
  2001年   2篇
  2000年   3篇
  1999年   1篇
  1998年   3篇
  1996年   2篇
  1995年   3篇
  1994年   1篇
  1993年   1篇
  1992年   2篇
  1991年   2篇
  1990年   1篇
  1989年   2篇
  1988年   3篇
  1986年   1篇
  1985年   4篇
  1984年   4篇
  1983年   1篇
  1982年   1篇
  1980年   1篇
  1978年   2篇
  1977年   2篇
  1976年   1篇
  1975年   1篇
  1974年   3篇
  1973年   2篇
排序方式: 共有150条查询结果,搜索用时 74 毫秒
1.
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.
Members of parliament are key actors for the implementation of energy transitions, such as phasing out nuclear power. Before legislators can cast their maybe decisive vote in parliament, they need to run for office and actively strive for election. This paper assesses what political candidates oppose renewable energy transitions and questions whether the energy issue matters in national elections, and thus has consequences for the implementation of new sustainable energy sources. We analyze these questions by first describing the specific characteristics of political candidates. The paper then evaluates the relevance of the energy issue for electoral success in three national elections in Switzerland (2007, 2012, and 2015). Based on candidate data from the voting advice application smartvote.ch, we find that female candidates support ETs more than men do; that especially the French‐speaking part of the country is more in favor of a nuclear phase‐out, and that younger candidates are also more open toward restructuring the energy system than older candidates are. Our models further show that the energy issue does not matter in elections, independently from its salience in the respective election campaigns. Candidates are thus relatively free to choose their position on the issue and do not have to fear consequences at the ballot. However, candidates of center parties, in contrast to the pole parties, are sensitive to the energy issue and reflect public mood in their positions.  相似文献   
4.
5.
6.
This article presents a conceptual framework for analysing the governance of natural resource use, as governance is often the primary issue when natural resources are overexploited and degraded. It addresses both spontaneous and active governance, including institutional change induced by development co‐operation. Drawing on existing frameworks of institutional analysis, fundamental modifications are presented to adapt the concept to the context of international co‐operation, and to include dynamic aspects of institutional change as well as multiple actor interactions. Tested in several case studies, the framework was found suitable and relevant for use in project planning and evaluation, as well as for comparing governance issues across cases in a conceptually rigorous way. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   
7.
Although there has been evidence for some time of a sex difference in depression, relatively little research has examined the developmental process by which women come to be at greater risk than men for depression. In this paper, the developmental pattern of depressed affect is examined over early and middle adolescence, with a special focus on the patterns of boys as compared to girls. In addition, a developmental model for mental health in adolescence is tested for its power in explaining the emergence of gender differences in depression. Longitudinal data on 335 adolescents randomly selected from two school districts were used to test the hypotheses. Results revealed that girls are at risk for developing depressed affect by 12th grade because they experienced more challenges in early adolescence than did boys. The sex difference in depressed affect at 12th grade disappears once early adolescent challenges are considered.This research was supported in part by grants MH30252/38142 to A. Petersen. We gratefully acknowledge the contributions of study participants and staff. Portions of this material were presented in a symposium at the 1988 meeting of the Society for Research on Adolescence, and one at the 1989 meeting of the Society for Research in Child Development.Received Ph.D. from University of Chicago in 1973. Research interest in biopsychosocial development in adolescence, with a focus on sex differences in mental health.Research interests include adolescent mental health, and parent and peer relationships.Received Ph.D. in psychology from The Pennsylvania State University. Research interests include development of affective and conduct disorders, especially sex differences in these problems.  相似文献   
8.
We conducted a short-term longitudinal study examining the structure of coping behavior and the relationship between coping style and depression during adolescence. The sample consisted of 603 adolescents in Grades 6–11 who were surveyed in the fall of 1989 and again in the fall of 1990. A two-dimensional model of coping was found using confirmatory factor analysis with the factors being approach and avoidant coping. Four cross-sectional and seven longitudinal coping groups were formed to explore group differences in depression. Approach copers reported the fewest symptoms of depression, while avoidant copers reported the most. Subjects who changed over time from approach to avoidant coping evidenced a significant increase in depressive symptoms, whereas subjects who switched from avoidant to approach coping displayed a significant decrease in depression over a one-year period. These findings imply that adolescents who are able to elicit social support, engage in problem solving, and cognitively restructure events within a positive light are more likely to successfully negotiate the challenges of adolescence.This research was supported by a grant from the William T. Grant Foundation (8912789), Anne C. Petersen, Principal Investigator. The writing of this article was supported by the National Institute of Mental Health Research Training Grant 5 T32MH18387-06 in Child Mental Health/Primary Prevention.Received Ph.D. in Human Development and Family Studies from Pennsylvania State University. Research interests include adolescent mental health and community research.Received his Ph.D. in Human Development and Family Studies from Pennsylvania State University. Research interests include adolescent mental health and research methodology.Received degree from the University of Chicago. Research interests are in biopsychosocial development in adolescence, with a focus on sex differences in mental health.  相似文献   
9.
The Targeted Jobs Tax Credit (TJTC) is a representative redistributive incentive. Initially, proponents saw TJTC as an elegant program, efficiently promoting labor market behavior that would solve the employment problems of many disadvantaged job seekers. However, interest groups distorted the credit into a windfall for businesses that hire large numbers of low wage workers. The policy theories incorporated into TJTC, which emphasized continual program reform and minimized program management by public administrators, provided a setting conducive to interest group distortion. Because few representatives of the disadvantaged participated in the oversight process, special interests undermined TJTC being reformed through empirical evaluation. This experience indicates that without major changes in the policy process, narrowly targeted rzdistributive policies should be avoided.  相似文献   
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