全文获取类型
收费全文 | 127篇 |
免费 | 9篇 |
国内免费 | 3篇 |
专业分类
系统科学 | 24篇 |
教育与普及 | 2篇 |
现状及发展 | 6篇 |
综合类 | 100篇 |
自然研究 | 7篇 |
出版年
2022年 | 1篇 |
2018年 | 1篇 |
2016年 | 1篇 |
2015年 | 1篇 |
2014年 | 2篇 |
2013年 | 1篇 |
2012年 | 12篇 |
2011年 | 4篇 |
2010年 | 3篇 |
2009年 | 4篇 |
2008年 | 5篇 |
2007年 | 6篇 |
2006年 | 6篇 |
2005年 | 10篇 |
2004年 | 7篇 |
2003年 | 6篇 |
2002年 | 17篇 |
2001年 | 7篇 |
2000年 | 9篇 |
1999年 | 3篇 |
1998年 | 3篇 |
1997年 | 2篇 |
1996年 | 2篇 |
1995年 | 4篇 |
1994年 | 5篇 |
1993年 | 1篇 |
1992年 | 4篇 |
1991年 | 5篇 |
1990年 | 1篇 |
1989年 | 5篇 |
1986年 | 1篇 |
排序方式: 共有139条查询结果,搜索用时 9 毫秒
1.
2.
3.
细胞色素P450表达在植物防御反应中的作用 总被引:8,自引:0,他引:8
细胞色素P450是广泛存在植物体中的一种多功能氧化酶,它在植物对病原侵袭的防御反应中起着重要的作用.本文从植物P450的多样性,及在寄主-病原物不亲和互作中的特异表达,证明了P450参与植物的抗病反应;同时,分析P450在植物抗病反应的作用途径,说明P450在植物抗病基因工程中存在巨大的应用潜力. 相似文献
4.
《Journal of Natural History》2012,46(18):1431-1442
Predator‐induced defence responses have been reported in 15 species of ciliates representing three subclasses: Hypotrichia, Stichotrichia and Hymenostomia. However, the discovery of this phenomenon in such distantly related groups suggests that it could be more widespread within the Ciliophora. In laboratory experiments, we tested 23 potential prey species with a range of potential predators including other ciliates (12 spp.), amoebae (two spp.), rotifers (two spp.), a turbellarian worm (Stenostomum sphagnetorum), and an oligochaete worm (Chaetogaster sp.). In each experiment, one predator species was incubated for 24?h with one potential prey species and the latter was examined for evidence of a defence response. One new example of predator‐induced morphological change was recorded (Euplotes viridis) and detailed observations were made for one poorly known example (E. eurystomus). Both species significantly increased their width (by about 35% and 23%, respectively) in the presence of the turbellarian worm S. sphagnetorum. An induced life cycle change was recorded for the first time among hypotrichs with E. muscorum exhibiting significantly increased rates of encystation in the presence of the ciliate predators Dileptus anser and Spathidium sp. Finally, Euplotes patella, Euplotes sp. and Stylonychia pustulata, which are usually regarded as omnivorous rather than predatory ciliates, all induced morphological change in Colpidium kleini, the C. kleini cells becoming significantly shorter and wider. No examples of induced defence response were found among groups other than hypotrichs and hymenostomes. 相似文献
5.
Andrei Sourakov 《Journal of Natural History》2015,49(39-40):2397-2415
Crotalaria plants and Utetheisa ornatrix are closely linked to each other: the larvae destroy the seeds, while the moth depends on hostplants for alkaloids. To better understand the ongoing co-evolution, the present study examines how native hostplants compare to exotic ones. Leaf-feeding on Crotalaria pumila, C. rotundifolia, and C. incana, native to the moth’s range, led to faster larval development than on the exotic C. lanceolata, C. spectabilis, and C. pallida. Seed-feeding on all species of Crotalaria led to accelerated larval development and a resultant larger adult moth, and correlates with a higher nitrogen content in the plant tissues. These results add a novel dimension to the previous studies of reproductive biology of this model organism. In controlled settings, mature larvae showed preference for leaves of C. spectabilis over those of other species, perhaps due to the higher alkaloid content. Differences in morphology and phenology of Crotalaria determine the ecology of U. ornatrix populations in Florida. The introduction of novel hostplants, on which U. ornatrix can have a significant negative effect and which are of concern to humans as invasive toxic weeds, has greatly expanded the niche occupied by this moth. Possible co-evolution of Utetheisa sensu lato and plant defences in the genus Crotalaria is discussed. 相似文献
6.
杨山林 《江西科技师范学院学报》2009,(3):68-70
高校对安全教育的忽视造成学生安全意识薄弱,防范技能缺乏,这已成为校园安全事故的主要原因之一。通过开展心理防范教育,培养学生的安全意识和防范技能,调动学生的安全需求,引导学生积极参与安全实践活动,可以在校园内形成一道坚固的安全心理防线,最终构建“人防、物防、技防”和“心防”相结合的整体防控网络.创建平安和谐校园。 相似文献
7.
8.
程培鹏 《徐州师范大学学报(自然科学版)》2002,20(2):76-78
采用资料法、观摩统计法及对比分析法对蓝球比赛中攻与防的关系重新加以认识和分析,研究表明:加强防守时对进攻意图的预先判断能力和合理位置的选择能力,以及加强对比赛对手投篮得分点的分析和对篮球理论,规则的研究,有利于防守从被动向主动转变,有利于提高整体的防守水平。 相似文献
10.
刘平舟 《山西师范大学学报:自然科学版》1992,(3)
本文详细讨论了一类具集群防御特性的Predator-prey系统的奇点的稳定性质及其Hopf分支,并对一个著名的数学生态学悖论进行了讨论。文中结果对[2,4]的结论提出了质疑。 相似文献