共查询到20条相似文献,搜索用时 31 毫秒
1.
2.
3.
M.C. Boulter 《Palaeogeography, Palaeoclimatology, Palaeoecology》1975,18(1):65-76
Ice-wedge casts in southern Quebec are exclusive to deposits pertaining to two ice front positions during the retreat of the Laurentides ice sheet: the Highland front morainic system located at the southern margin of the St. Lawrence lowlands, and the St. Narcisse front morainic system located at the southern margin of the Laurentides highlands. Wedge casts filled with sand and gravel are relic of true ice wedges and give evidence of former permafrost conditions in the ground during the retreat of the ice sheet in that area, between 13 000 and 11 000 years B.P. Mean annual air temperature was lower than −6°C, a difference of 8–12° with the present-day temperature. Humidity was high enough to allow the growth of ice wedges in the permafrost. These rigorous climatic conditions prevailed during a few centuries only. There is no positive evidence of tundra conditions in southern Quebec young than 11 000 years ago. 相似文献
4.
5.
6.
Chromosome pairing was studied in the following hybrids: Hibiscus radiatus-meeusei (tetraploid F1), H. sabdariffa-meeusei (tetraploid F1 and spontaneous allooctoploid F2), and hexaploid H. acetosella-(sabdariffa-meeusei). Genome constitutions of the species adduced from these data are symbolized as follows: H. radiatus and H. acetosella, AABB; H. meeusei, AAXX; H.sabdariffa, XXYY or AAYY. 相似文献
7.
LEONARD WILLIAM SCHEIBEL 《The Journal of eukaryotic microbiology》1991,38(1):105-106
8.
Nature's Conscience ‐ The Life and Legacy of Derek Ratcliffe,by Des Thompson,Hilary Birks,John Birks. Peterborough,UK: Langford Press, 2015, 572 pp. Softback,including many colour photographs. £23. Hardback also available. ISBN 978‐1‐904078‐59‐3.
下载免费PDF全文
![点击此处可从《Biological journal of the Linnean Society. Linnean Society of London》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Pat Morris 《Biological journal of the Linnean Society. Linnean Society of London》2016,117(2):401-402
9.
10.
11.
12.
13.
14.
15.
16.
描述了中国云南姜科Zingiberaceae一新种——苍山象才参Roscoea cangshanensisM.H.LUO,X.F.Gao&H.H.Lin。该种与大理象牙参R.forrestii Cowley在体态上相近,但唇瓣深裂成2裂片,每个裂片再2裂,基部收缩成具白色条纹的柄,叶片较狭窄,(2-)7-24×1.5-2.5cm,叶片基部狭缩成叶柄状而不同。该新种叶片基部狭缩成叶柄状,唇瓣倒卵状楔形,长2.5-3.5cm,宽2.5-3.0cm,基部收缩成具白色条纹的柄,与长柄象牙参R.debilis Gagnep.相似,但苞片非管状,较短,长5-15mm,隐藏于叶鞘内,花冠管较长,10-12.5cm,唇瓣深裂成2裂片,每个裂片再2裂,可与后者明显区别。 相似文献
17.
18.
19.
20.
In greenhouse experiments Hirschmanniella oryzae, H. imamuri, and H. spinicaudata depressed and delayed the tillering and flowering of rice, and suppressed root and shoot growth and grain yield. 相似文献