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   117篇
  免费   1篇
系统科学   2篇
丛书文集   1篇
现状及发展   3篇
综合类   39篇
自然研究   73篇
  2023年   1篇
  2020年   2篇
  2019年   1篇
  2018年   5篇
  2017年   1篇
  2016年   4篇
  2015年   2篇
  2014年   6篇
  2012年   65篇
  2011年   7篇
  2010年   3篇
  2009年   2篇
  2008年   2篇
  2007年   2篇
  2006年   4篇
  2004年   1篇
  2002年   1篇
  2001年   4篇
  1999年   1篇
  1997年   1篇
  1996年   1篇
  1995年   1篇
  1994年   1篇
排序方式: 共有118条查询结果,搜索用时 15 毫秒
91.
Three new species of Copidognathinae (Acari: Halacaridae) are described from the eastern coast of southern Africa (Mozambique; South Africa: Eastern Cape and KwaZulu-Natal). Copidognathus caloglossae sp. nov. and Acarothrix umgenica sp. nov. were collected in mangrove habitats, whereas Copidognathus xaixaiensis sp. nov. was collected on a rocky shore. Acarothrix umgenica represents the first record of the genus Acarothrix Bartsch, 1990 from the African continent.  相似文献   
92.
《Journal of Natural History》2012,46(6):1611-1615
Nesting behaviour and prey of two species of Pseudoplisus, a gorytine wasp genus in the sphecid subfamily Nyssoninae, are described. P. natalensis is a solitary nester in southern Africa nesting often in the soil in flower-pots. P. ranosahae in Madagascar nests in the ground in large aggregations. Both species show a high degree of prey specificity. Nests are provisioned only with large adult froghoppers (Aphrophoridae), P. natalensis preying on Ptyelus grossus and P. ranosahae on Ptyelus goudoti.  相似文献   
93.
预测中非BG盆地R区块Kubla组地层砂体在横向、纵向上的重点聚集区,确定有利油气聚集的重点层位.以BG盆地的区域地质、沉积相类型、钻井岩心和测井资料为基础,以高分辨率层序地层学理论及技术方法为指导,采用多级次基准面旋回层序划分和等时对比方案,对R区块Kubla组沉积-层序进行精细分析,识别出长期、中期、短期3个级次的基准面旋回层序,重点对短期和中期旋回层序的划分方式、层序类型和组合叠加式样进行了讨论.确定向上“变深”的非对称型和对称型旋回为各级次旋回层序的主要结构类型.以中期旋回层序为等时地层格架、短期旋回层序作为等时地层单元,建立起R区块Kubla组高分辨率等时地层格架.中期上升半旋回底部和下降半旋回顶部砂体的横向连通性较好,垂向上MSC3上升半旋回底部以及MSC2下降半旋回顶部砂体发育较好,是油气富集的有利层位.  相似文献   
94.
 “一带一路”发展倡议为沿线国家优势互补、开拓发展提供了新的机遇,是国际合作的新平台。撒哈拉以南非洲地区林木资源丰富,是中国“一带一路”发展倡议大背景下的重要合作方向,增强与该地区林木资源投资合作建设,是推动“一带一路”建设的重要内容。本文综合考虑了该地区林木资源禀赋、社会经济因素、自然地理因素及政治外交因素等,基于多级模糊综合评价方法构建了撒哈拉以南非洲地区林木资源投资风险分析模型,通过评价指标选取、指标体系建立和指标权重分析,对主控投资因素进行研究和评价分析,对该地区林木资源投资风险分析进行了综合评估。  相似文献   
95.
作为语言规划研究的重要组成部分,语言规划目标并没有引起足够重视。从目标的角度对南非四个阶段的语言政策进行分析,再次体现目标在语言规划研究过程中的重要性。  相似文献   
96.
A recently published paper on some Helix species from the East Mediterranean basin is briefly reviewed. Parts of the results of the authors of that study are erroneous because they are based on a misinterpretation of some of the taxa involved. An analysis of the actually studied taxa is presented, and the essential consequences for nomenclature and phylogeny are discussed.  相似文献   
97.
《Journal of Natural History》2012,46(9):1349-1365
The taxonomy of the African representatives of the wolf spider genus Ocyale is revised. Fundamental taxonomic problems were encountered which resulted in confusion in the literature between Ocyale and Pisaura and thus potential instability of the type genus of the family Pisauridae. For reasons of taxonomic stability, a new type species for Ocyale is proposed here: O. neatalanta. Besides the type species, O. dewinterae n.sp., O. discrepans Roewer, 1960, O. grandis n.sp. and Ocyale guttata Karsch, 1878, are described and an identification key is provided. Ocyale spissa (Lenz, 1895) proved to be a junior synonym of O. guttata. Ocyale maculata (L. Koch, 1875), O. spissides Strand, 1907, O. fera Strand, 1908, O. ingenua (Karsch, 1879) and O. conspersa Karsch, 1879, were found to be either nomina dubia or incertae sedis.  相似文献   
98.
The Chorthippus biguttulus group includes a number of common European species that are difficult to distinguish morphologically but are easily recognized in the field by the distinctive calling songs of the males. These song-patterns have not previously been studied in Spain and as a result the Iberian members of the group have been misidentified in almost all the extensive Spanish literature on the ecology and cytogenetics of these insects. In this study the male calling songs of all six members of the group known from the Iberian Peninsula and North Africa and fully described and illustrated with oscillograms at several different speeds. The songs of the three species known only from Iberia or North Africa, jacobsi, yersini and marocanus, are fully described for the first time (marocanus is here raised in rank from subspecies). Notes on recognition, using both morphology and song, are given for each species, and two identification keys are provided, one based on morphology and the other on song. It is shown that the three species biguttulus, brunneus and mollis, previously believed to be widespread in Iberia, are absent from most of the peninsula.  相似文献   
99.
100.
The tropical African species of the genus Exoprosopa Macquart placed by Bezzi (1924) in his group 10, E. busiris are reviewed. A key, short diagnoses and outline distributions are provided for each species. E. albonigra Bezzi and E. saskae Szilády are shown to be synonyms of E. luteicosta Bezzi; E. engyoptera Hesse a synonym of E. brevinasis Bezzi; and E. ferrieri Hesse a synonym of E. decastroi Hesse. Two new species are described; E. selenops from Kenya and E. glossops from Nigeria.  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