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   1533篇
  免费   79篇
各国政治   84篇
工人农民   65篇
世界政治   109篇
外交国际关系   145篇
法律   780篇
中国政治   11篇
政治理论   408篇
综合类   10篇
  2023年   19篇
  2022年   25篇
  2021年   22篇
  2020年   41篇
  2019年   63篇
  2018年   59篇
  2017年   73篇
  2016年   87篇
  2015年   41篇
  2014年   73篇
  2013年   212篇
  2012年   71篇
  2011年   51篇
  2010年   45篇
  2009年   50篇
  2008年   56篇
  2007年   71篇
  2006年   51篇
  2005年   65篇
  2004年   51篇
  2003年   50篇
  2002年   47篇
  2001年   30篇
  2000年   21篇
  1999年   26篇
  1998年   16篇
  1997年   14篇
  1996年   8篇
  1995年   18篇
  1994年   11篇
  1993年   5篇
  1992年   20篇
  1991年   7篇
  1990年   11篇
  1989年   11篇
  1988年   8篇
  1987年   10篇
  1986年   11篇
  1985年   7篇
  1984年   4篇
  1983年   8篇
  1982年   5篇
  1981年   3篇
  1980年   6篇
  1975年   4篇
  1973年   3篇
  1970年   2篇
  1969年   3篇
  1966年   3篇
  1962年   2篇
排序方式: 共有1612条查询结果,搜索用时 15 毫秒
41.
Faced with pressing climatic changes, scientific and industrial interests are vying to develop crops that can survive drought, floods and shifting pest regimes. Increasingly, they look for solutions in an unlikely place: the gene pools of wild plants. Crop wild relatives (CWR) – species closely related to crops, including their ancestors – offer breeders the allure of retracing the domestication bottleneck, infusing genomes of modern crops with ‘lost’ genetic variety. Yet wild relatives also confront threats from climate change, urbanization and expansion of industrial agri-food. Thus, CWR, seen as both salvational and threatened, have become an international conservation and food-security priority. It is my contention that, in their common project to harness wild-relative potential, conservation and breeding science are co-evolving to extend seed commodity relations into new spheres. I examine enclosures along two fronts: first within ‘systematic CWR conservation’, where ‘in situ’ approaches, typically regarded as empowering and sustainable alternatives to ‘ex situ’, instead may support a complementary system of value extraction; second, in breeding and biotechnology research, which produces new value for CWR while profoundly shaping upstream conservation priorities. An important finding is that although today’s ‘ex situ-centric’ complementarity favors dispossession, an ‘in situ-centric’ approach could foster democratic renewal of biocultural diversity.  相似文献   
42.
43.
That public officials influence public policy is generally agreed upon, but the issue of how individual officials gain this influence is less developed in the literature. Here, the stories and experiences of 10 officials, active in local environmental governing in Sweden, are used to identify, describe, and discuss key strategies for gaining policy influence. The result shows the importance of accessing key politicians; avoiding isolation within the administration; developing long-term strategies; and being skilled in communication, networking, and generating external resources. The way these officials act and think challenges some well-established theoretical notions and adds empirical insights to the democratic dilemma of bureaucratic power.  相似文献   
44.
Although the relation between family relationships and the timing of sexual debut has been the focus of many studies, research on mediating factors is scarce. This study examines whether low levels of family cohesion result in an earlier onset of romantic and sexual experiences, and whether the link between family cohesion and an early sexual debut is mediated by early romantic initiation. A longitudinal sample of 314 adolescent girls and 222 boys, aged 12–17 at Wave 1, completed questionnaires at three measurement points with three year intervals. The results showed that sexual debut followed romantic initiation for 77% of the participants. For early adolescent females (aged 12–14), high levels of family cohesion resulted in a later sexual debut and this association was fully mediated by a delay of romantic initiation. Among boys and older girls, timing of romantic initiation did not mediate the link between family cohesion and timing of sexual initiation. Early adolescent girls who have negative relationships with their parents turn to romantic relationships for intimacy and support, which subsequently provide the opportunity for an early sexual debut. Low levels of family cohesion thus primarily precipitate romantic initiation and sexual initiation appears to be secondary to this process among girls in this age group.  相似文献   
45.
Food production has been changing significantly in recent years as a result of climate change and of growing demand for food. This article aims to understand the link between food security and international security in the context of climate change, applying a systematic and qualitative analysis of the literature using the bibliometric method. This research observes that climate change tends to affect agricultural productivity, exposing societies to risk and the need for migration. However, good governance, together with international cooperation, can reduce the hazards of food insecurity, strengthening ties between countries and stimulating a fairer and more inclusive form of international trade.  相似文献   
46.
47.
48.
The pandemic of Covid-19 has exposed the veins of inequality in Latin America. With a socioeconomic disaster looming, social emergency policies seemed inevitable. Yet while governments argue over the continuity of such policies and whether the fiscal rules in place should be respected, no sustainable response has come out. This essay problematises whether the pandemic could represent a critical juncture to forge ahead with political narratives that highlight tax exemptions and privileges enjoyed by the rich. We analyse the mitigation measures adopted by Argentina, Brazil, Chile and Uruguay and their repercussions on the debate surrounding progressive tax reforms to fund social schemes.  相似文献   
49.
DNA is one of the fastest growing tools in forensic sciences, increasing reliability in forensic reports and judgments. The use of DNA has increased in different areas of the forensic sciences, such as investigation of plant species, where plastid DNA has been used to elucidate and generate evidence in cases of traceability of genetically modified and controlled plants. Even with several advances and the practice of using DNA in forensic investigations, there are just few studies related to the identification of genetic tools for the characterization of drug and nondrug-types of Cannabis. Herein, the whole plastomes of two drug-type Cannabis are presented and have their structures compared with other Cannabis plastomes deposited in the GenBank, focusing in the forensic use of plastome sequences. The plastomes of Cannabis sativa “Brazuka” and of the hybrid Cannabis AK Royal Automatic presented general structure that does not differs from the reported for other C. sativa cultivars. A phylogenomic analyses grouped C. sativa “Brazuka” with the nondrug C. sativa cultivars, while the hybrid Cannabis AK Royal Automatic placed isolated, basal to this group. This suggests that the analysis of plastomes is useful toward genetic identification of hybrids in relation to C. sativa.  相似文献   
50.
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   
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