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   355篇
  免费   23篇
  378篇
  2022年   3篇
  2021年   5篇
  2020年   4篇
  2019年   3篇
  2015年   6篇
  2014年   9篇
  2013年   12篇
  2012年   19篇
  2011年   22篇
  2010年   9篇
  2009年   9篇
  2008年   14篇
  2007年   12篇
  2006年   10篇
  2005年   17篇
  2004年   9篇
  2003年   5篇
  2002年   6篇
  2001年   5篇
  2000年   11篇
  1999年   3篇
  1998年   6篇
  1997年   3篇
  1996年   4篇
  1995年   4篇
  1994年   3篇
  1992年   5篇
  1991年   4篇
  1990年   8篇
  1989年   10篇
  1988年   5篇
  1987年   4篇
  1986年   4篇
  1982年   3篇
  1978年   8篇
  1976年   4篇
  1975年   3篇
  1971年   6篇
  1969年   7篇
  1962年   3篇
  1959年   6篇
  1957年   7篇
  1956年   6篇
  1951年   3篇
  1949年   5篇
  1938年   2篇
  1936年   2篇
  1935年   2篇
  1933年   4篇
  1930年   2篇
排序方式: 共有378条查询结果,搜索用时 15 毫秒
1.
2.
Protoscoleces from human, camel, cattle, sheep, goat (all from Kenya) and buffalo (from India) hydatid cysts were cultured under identical conditions in vitro using the diphasic culture system of Smyth (1979b). Organisms from all sources grew and segmented in culture. Genital anlagen developed in all cultured worms but further genital differentiation occurred only in cultures of cattle (testes) and camel (testes and genital pore) material. The possible significance of these results is discussed in relation to the general epidemiology of hydatid disease and the potential infectivity of the different strains to man.  相似文献   
3.
Two methods of semen collection were attempted on ten untrained dogs of several breeds. Manual manipulation as described proved most reliable for untrained dogs. Electro-ejaculation was attempted unsucessfully with twelve additional dogs.Two methods of insemination were compared. Equipment found most satisfactory is described and a modification suggested.  相似文献   
4.
5.
The properties of seven monogalactosyldiacylglycerols and six digalactosyldiacylglycerols, isolated from photosynthetic membranes and possessing different levels of fatty acid unsaturation, have been studied by the monolayer technique and compared with those of the fully saturated compounds. In addition, the monolayer properties of sulphoquinovosyldiacylglycerols and phosphatidylglycerols from higher plant chloroplasts, and several hexadecenoic acids have been measured.Monogalactosyldiacylglycerols containing saturated fatty acids form a condensed monolayer similar to that of saturated phosphatidylcholines. The naturally occurring monogalactosyldiacylglycerols, of which the double bond index ranged from 0.6 to 3.9, possessed comparable force-area curves suggesting that headgroup interactions play a more important role in packing behaviour than in phosphatidylcholines. Although digalactosyldiacylglycerols containing fully saturated fatty acids form a more expanded monolayer than the corresponding monogalactosyldiacylglycerols, the degree of expansion of the monolayer due to the presence of unsaturated fatty acids in the naturally occurring digalactosyldiacylglycerols is much less than in monogalactosyldiacylglycerols. Monogalactosyldiacylglycerols and digalactosyldiacylglycerols from a single species have very similar monolayer properties, and the presence of sulphoquinovosyldiacylglycerols and phosphatidylglycerols in the proportions in which they occur in higher plant chloroplasts does not have any condensing effect on a monolayer of galactolipids  相似文献   
6.
L. B. Macpherson 《CMAJ》1962,86(14):648-649
  相似文献   
7.
8.
R. A. Macpherson 《CMAJ》1953,68(2):165-166
  相似文献   
9.
10.
Rhinocerotids are particularly abundant and diversified in Neogene deposits of the Indian subcontinent, but their systematics is far from being well defined. Based on the revision of old collections and new findings from the Early Miocene of the Bugti Hills and Zinda Pir, Pakistan, ‘Aceratherium blanfordi Lydekker, 1884’ is a chimera, consisting of two dentally convergent but postcranially distinct rhinocerotid taxa: Pleuroceros blanfordi and Mesaceratherium welcommi sp. nov. Postcranial features appear to be much more diagnostic than craniodental morphology in this case. A phylogenetic analysis based on 282 morphological characters scored for 28 taxa (four outgroups and ingroup including both taxa of interest and a ‘branching group’) strengthens this statement and supports Pleuroceros and Mesaceratherium as monophyletic genera within Rhinocerotinae. Both genera are recognized for the first time outside Europe. In the Bugti Hills, P. blanfordi and M. welcommi are part of an exceptionally diversified rhinocerotid fauna, with up to nine species associated in the same locality (Kumbi 4f). This rhinocerotid assemblage confirms the earliest Miocene age (Agenian/Aquitanian) of the upper member of the Chitarwata Formation as a whole. Coeval homotaxic rhinocerotid faunas from Europe (France, Czech Republic) and East Africa (Uganda, Kenya) support broad and sustainable rhinocerotid interchanges amongst South Asia, Europe, and Africa under compatible environmental conditions throughout earliest Miocene times. © 2010 The Linnean Society of London, Zoological Journal of the Linnean Society, 2010, 160 , 139–194.  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