全文获取类型
收费全文 | 49篇 |
免费 | 0篇 |
国内免费 | 22篇 |
专业分类
教育 | 26篇 |
科学研究 | 35篇 |
体育 | 7篇 |
综合类 | 1篇 |
信息传播 | 2篇 |
出版年
2022年 | 1篇 |
2016年 | 1篇 |
2015年 | 2篇 |
2014年 | 3篇 |
2013年 | 4篇 |
2012年 | 4篇 |
2011年 | 5篇 |
2010年 | 4篇 |
2009年 | 4篇 |
2008年 | 7篇 |
2007年 | 2篇 |
2005年 | 4篇 |
2004年 | 2篇 |
2003年 | 5篇 |
2002年 | 4篇 |
2001年 | 2篇 |
2000年 | 1篇 |
1998年 | 1篇 |
1997年 | 1篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1994年 | 2篇 |
1992年 | 2篇 |
1990年 | 1篇 |
1987年 | 2篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1984年 | 3篇 |
排序方式: 共有71条查询结果,搜索用时 15 毫秒
12.
13.
14.
Cypripedium subtropicum S. C. Chen et K. Y. Lang is a phytogeography-
cally significant new species with its habit, inflorescence and column very similar to
those of Selenipedilum of tropical America. It is found in Mêdog of southeastern Xi-
zang, China. Its slender leafy stem bears at the summit a many-flowered raceme, am-
ounting to 1.5 m in height. Although its ovary is unilocular—this is the reason why
we place it in Cypripedium, the column characters resemble those of Selenipedilum. For
example, the staminode is rather small and its long stalk is very similar in texture and
color to the filament of the fertile stamens. Obviously, it is a primitive new species re-
lated to Selenipedilum based on the similarities mentioned above.
In the subfamily Cypripedioideae, as generally recognized, Selenipedilum is the
most primitive genus, from which or whose allies Cypripedium is derived. Of phyto-
geographical significance is the fact that Selenipedilum occurs in Central America and
northern South America, while a cypripedium akin to it is discontinuously distributed
in subtropical Asia. This suggests that Selenipedilum or Selenipedilum-like form be
once continually distributed in North America and eastern Asia when the climate there
was warmer, as it is in the subtropics today. The floristic relationship between Central
America and subtropical Asia appears to be closer than expected, as shown by the dis-
tribution patterns of Tropidia, Erythrodes, etc. Based on the occurrence of all six sec-
tions and particularly the most primitive form in eastern Asia, Cypripedium seems to
be of Asian, rather than Central American, origin. Selenipedilum possesses some very
primitive characters, such as trilocular ovary, vanilla-scented fruit, seed with sclerotic
testa, simple column and more or less suffrutescent habit. The latter is considered by
Dahlgren & Clifford (1982) to be one of ancestral characters of monocotyledons, which
is now very rare not only in Orchidaceae but also in all monocotyledons. It is indeed
necessary to make further investigations on Selenipedilum and also the new species pub-lished here, as well as a detailed comparison between them. 相似文献
15.
16.
17.
导语:成功人人渴求。一个人要想获得成功,机遇非常重要,但更重要的是汗水,只有勤奋刻苦,矢志不渝,咬紧牙关坚持到底,成功之花才会绽放。这样的事例,古今中外,举不胜举。所以,你若想摘取成功的花朵,就请奋发向上,挥汗如雨,执着前行。 相似文献
18.
他成为全国石斛行业乃至中药材种植行业公认的最成功的、贡献最大的会长——而他所做的一切,皆为了带领百姓致富和促进当地经济的繁荣。据资料显示,石斛是兰科植物之一,可入药,对人体有驱解虚热,益精强阴等疗效。云南省龙陵县素有"滇西雨屏"之美誉, 相似文献
19.
应国家主席胡锦涛的邀请,马其顿总统布兰科·茨尔文科夫斯基2007年12月4日对我国进行国事访问。为了纪念茨尔文科夫斯基总统访华,同时,也是为了表达中马两国人民的友谊,中国集邮总公司和外交部集邮协会专门印制了特种纪念封。12月4日晚,"马其顿共和国总统布兰科·茨尔文科夫斯基对中华人民共和国进行国事访问纪念封"首发仪式在北京钓鱼台国宾馆举行。 相似文献
20.