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   392篇
  免费   12篇
  2024年   1篇
  2023年   5篇
  2022年   3篇
  2021年   1篇
  2020年   17篇
  2019年   20篇
  2018年   39篇
  2017年   28篇
  2016年   26篇
  2015年   22篇
  2014年   19篇
  2013年   74篇
  2012年   20篇
  2011年   24篇
  2010年   18篇
  2009年   11篇
  2008年   9篇
  2007年   10篇
  2006年   11篇
  2005年   5篇
  2004年   5篇
  2003年   6篇
  2002年   3篇
  2001年   1篇
  2000年   4篇
  1999年   1篇
  1998年   2篇
  1997年   3篇
  1996年   3篇
  1994年   3篇
  1993年   2篇
  1989年   1篇
  1988年   2篇
  1983年   1篇
  1982年   1篇
  1981年   2篇
  1980年   1篇
排序方式: 共有404条查询结果,搜索用时 15 毫秒
381.
This article analyzes the al‐Mahdi Scouts, a Lebanese scout group affiliated with Hezbollah. After introducing Hezbollah's social services in Lebanon, the al‐Mahdi Scouts' multifaceted identity and main activities are illustrated. The role in Lebanese society is investigated, along with its cooperation with other scout groups in Lebanon, which takes place mostly within the framework of the Lebanese Scout Federation. I also highlight two controversial issues that emerged in the research. First, it is shown how blurred the distinction is between education and indoctrination. Second, the accusations of terrorism are considered, with two possible approaches identified. The first one looks at Hezbollah as a homogeneous organization, while the second one distinguishes between its military, political, and social wings. While the first approach can legitimately accuse the al‐Mahdi Scouts of terrorism, I argue that the second one is more appropriate because it judges them for their own actions. We cannot just look at this group as Hezbollah's recruitment tool, because its role is more complex and significant. This group provides a portion of Lebanese youth with skills to improve their future and succeed in life, even if it does so by propagating Hezbollah's ideals and beliefs.  相似文献   
382.
383.
384.
ABSTRACT

Contrary to Russia’s expectations, military intervention into Ukraine only strengthened the Ukrainian civic nation. As a number of polls demonstrate, since 2014 there is a growing trend that the vast majority of Ukrainians, also in the government-controlled areas of the Donbas, identify themselves, first and foremost, as Ukrainian citizens. Regional and local identity is not their primary choice anymore and there are clear indicators of a strong civic identity that favors a unitary Ukraine. The lack of progress for a solution of the conflict in the Donbas impacts upon Ukrainian public opinion which, in turn, puts pressure on the Ukrainian authorities: there is a wide acceptance of a diplomatic solution to the conflict and readiness for some compromises but the reintegration of the occupied territories should take place according to pre-war conditions, without any federalization of Ukraine. Also, without establishing a stable security regime in the Donbas there is little support for an implementation of the political part of the Minsk-2 agreement. However, closer to the frontline, the more Ukrainians are ready for compromises. The promise of peace by new President Volodymyr Zelenskyy puts a question on what compromises his team may accept and justify in the eyes of Ukrainians.  相似文献   
385.
386.
ABSTRACT

In this paper, we analyze the isotopic niche and resource use of the guanaco (Lama guanicoe), pampas deer (Ozotoceros bezoarticus) and marsh deer (Blastocerus dichotomus) on the temperate plain of the northern Pampa region in the southeast of South America. The measured stable isotope compositions in bone tissue are δ13C, δ15N and δ18O. All the analyzed samples were recovered from different archaeological sites from the late Holocene. According to the results, the guanaco was strictly confined to the Pampa plain environment, developing a broad niche based on C3 plants and a variable contribution of C4 grasses within a grazing trend. The pampas deer preferentially used the Pampa plain, but also the prairies on the borders of the wetland, showing eurioic characteristics and a narrower niche based on C3 plants. In turn, the marsh deer was strictly confined to wetland environments, developing a C3 diet–base, within a narrow isotopic niche and stenoic characteristics. The three mammals showed a wide range of intraspecific variability, which was a key factor in their adaptability to spatial and temporal changes in the vegetation coverage. In fact, the temporal trends of their isotopic values were concurrent with the major climatic variations of the Holocene. Differences in the correlations between the values of both carbon sources in both deer species compared with the guanaco suggest a distinct chemical composition of their diet and/or differences in the allocation of nutrients. The isotopic values of nitrogen and spacing of the carbon sources in guanaco (pseudoruminant) and both deer species (ruminants) show no significant differences between them, thus establishing the values for local large herbivores. Significant correlations between δ13C and δ15N were found in the guanaco and marsh deer. The regional and extra–regional variability in the guanaco's δ13Ccollagen and δ15N probably reflect the clinal variations in the vegetation coverage and the amount of rainfall. The collagen isotope values in the guanaco throughout the entire Holocene show that the humid Pampa would have shifted between being a more recurrent mesic and temperate plain with minor phases of dry–mesic conditions like during the Little Ice Age, and a humid and warm one at the peaks of the Holocene Thermal Maximum and the Medieval Climatic Anomaly. The guanaco and the pampas deer adapted to all the climatic changes that happened on the humid Pampa until the biological invasions of large European mammals changed the herbivores’ guild composition of this vast plain, pushing them into peripheral habitats due to competition. The within–species variability in isotopic signals through time and space make it necessary to carry out adequate sampling before reconstructing the diets of local past populations.  相似文献   
387.
388.
This study examined the spatial and temporal patterns of the canopy layer urban heat islands (UHIUCL) in a small city in southeastern Brazil using the local climate zone (LCZ) system. We analysed the influence of weather conditions, LCZs characteristics, and local surface relief on the UHIUCL magnitudes. Mobile traverses were used to measure air temperatures during representative nights of wet and dry seasons. Daily maximum magnitudes were observed in compact classes (LCZs 3 and 7) under ideal weather conditions (dry, clear skies, and calm) and higher anthropogenic heat release (weekdays). Seasonal effects on LCZ thermal differences were negligible. The peripheral landscapes were warmer than the city centre in both seasons. Among the warmer areas in the city, magnitudes in compact LCZs 3 and 7 were consistently higher than in LCZ 6. In general, representative sites of the main ‘built’ LCZs in the study area exhibit similar inter-zone temperature patterns to those reported for cities of different sizes from tropical and midlatitude regions. Thermal contrasts of ΔTLCZ 3 − D in the study area reveal significant evidence that small cities can have as strong heat islands as bigger cities. These findings highlight the importance of the LCZ system to identify the main controlling factors driving such thermal differences and the need to extend the application of this approach in other South American cities to yield systematic data of UHIUCL for urban planning given the coming challenges of climate change over the region.  相似文献   
389.
390.
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