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31.
广西九万山藓类植物区系分析及其对划分热带,亚热带分界线的意义 总被引:13,自引:0,他引:13
九万山位于广西北部的中央(25°10’~25°25’N,108°27’E),界于泛北极植物区和古热带植物区的交汇处。其主要植被为亚热带常绿阔叶林。最高海拔为1693m,最低处仅170m。经对1850号标本的鉴定,共计有藓类植物35科、101属和189种。本文分析了九万山的藓类植物区系成分,将其划分为 10种类型。其中东亚成分最为丰富(39.33%),热带、亚热带成分次之(38.20%),而温带成分居第三位(18.54%)。本文选择了九万山临近的五个地区加以比较。其中,金佛山与九万山藓类植物的属和种的相似性系数分别为60.68%和36.87%,神农架为57.29%和33.13%。尖峰岭为48.83%和22.29%,西双版纳为57.29%和29.63%。而我国东部的武夷山则为69.86%和39.57%,其相似性系数在相比较的五个山区中为最高。九万山区有4个特有属并明显受喜马拉雅的影响。特别值得注意的是,在九万山区藓类区系中约有7%的种类是典型的热带成分。根据定量和定性的分析,笔者认为九万山的藓类区系表现出由热带向亚热带过渡的特性,其分界线可能位于九万山的南侧。 相似文献
32.
孤峰组最底部的牙形刺动物群 总被引:2,自引:2,他引:0
在孤峰组底部发现了包括Mesogondolella nankingensis在内的牙形刺动物群。Gondolella serrata Clark et Ethington,1962是Mesogondolella nankingensis(Jin,1960)的同义名,Mesogondolella nankingensis已被北美学者推荐为瓜达洛坪统底界的标志化石。因Mesogondolella na 相似文献
33.
34.
Summary We first perform a linear stability analysis of the Gierer-Meinhardt model to determine the critical parameters where the
homogeneous distribution of activator and inhibitor concentrations becomes unstable. There are two kinds of instabilities,
namely, one leading to spatial patterns and another one leading to temporal oscillations. Focussing our attention on spatial
pattern formation we solve the corresponding nonlinear equations by means of our previously introduced method of generalized
Ginzburg-Landau equations. We explicitly consider the two-dimensional case and find both rolls and hexagon-like structures.
The impact of different boundary conditions on the resulting patterns is also discussed. The occurrence of the new patterns
has all the features of nonequilibrium phase transitions. 相似文献
35.
Treatment of mammalian muscle with the divalent cation ionophore A23187 causes the release of Ca2+ from the sarcoplasmic reticulum and allows the ultrastructural changes of the mitochondria during Ca2+-uptake to be demonstrated in situ. Electron micrographs reveal that the mitochondria swell dramatically during uptake, before contracting again when the accumulated Ca2+ is released once more into the cytoplasm. When maximally swollen, the mitochondria are apparently subdivided and internal "septa" are formed. The ultrastructural details concerning these internal membranous structures are shown in detail and their significance is discussed. 相似文献
36.
Chen Guanfang Institute of Vertebrate Palaeontology Paleoanthropology Academia Sinica 《古脊椎动物学报》1991,(3)
<正> In the present paper a new caprine, Sinocapra minor gen. et sp. nov. is erected on the basis of several horn cores. The type specimen was collected by the Sino-American Palaeontology Expedition from the Upper Pliocene, Mazegou Formation, of Yunzhu Subbasin, Yushe Basin, Shansi province in 1988. All the other ones referred to the new genus were described and identified by Teilhard de Chardin and Trassaert (1938, p. 53, fig. 46) as Antilope gen. et sp. indet. They also came from Zhaozhuang, Yunzhu Subbasin and it is likely that they might be gathered from the same Formation as the type specimen judging by the yellow sandy clay filling into the horn cores. Magnetostratigraphic studies by Prof. N. Opdyke of the Yunzhu Subbasin indicates that this stratigraphic interval only includes the Gauss one, approximately 3.4 to 2.47 Ma. Accounts of the biostratigraphy and dating of Yunzhu Subbasin are giyen by Dr. R. H. Tedford and Dr. Z. Qiu in another paper. 相似文献
37.
38.
Naum I. Goldstein Roman N. Goldstein Mark N. Merzlyak 《International journal of biometeorology》1992,36(2):118-122
The physico-chemical characteristics and possible formation mechanisms of negative air ions are considered. It was found that the products of oxygen and nitrogen negative ionization reduce ferricytochromec and nitroblue tetrazolium, and that these reactions were inhibited by superoxide dismutase. The interaction of negatively ionized oxygen with water led to hydrogen peroxide accumulation, which was inhibited by tetranitromethane or catalase. Nitrogen ionization under these conditions caused the formation of the hydrated electron e
aq
—
and the superoxide anion O
2
—
. The data obtained indicate that the biological activity of negative air ions may be dependent on superoxide. The generation of reactive oxygen ions in the gas phase and also at a gas/water interface is described. A scheme for superoxide production under oxygen and nitrogen ionization is proposed. 相似文献
39.
Miya Hamai Toshisada Nishida Hiroyuki Takasaki Linda A. Turner 《Primates; journal of primatology》1992,33(2):151-162
Two cases of within-group infanticide and cannibalism were observed among the M Group chimpanzees of the Mahale Mountains,
Tanzania. In both cases, victimized infants were male, 5 – 6 months of age, and in good health when killed. Four to five years
have passed since the mothers of the victims immigrated into M Group as nulliparous immigrants. In one case the 2nd-ranking
male was observed to detach the infant from the mother's belly. Both infants were finally killed by the alpha male after several
adult males scrambled for the bodies. There was no evidence that the mothers had mated with males other than those of M Group.
Nor was there evidence that the mothers had restrictive mating relationships with some of the M Group adult males. What little
evidence is available shows that the mothers had mated mostly with adolescent and other immature males during their conception
cycles. However, at least in one case, the mother began to mate more with adult males rather than with immature males after
the infanticide. It is proposed that the function of within-group male infanticide can be explained by the male-male competition
hypothesis developed for hanuman langurs and other nonhuman primates. 相似文献
40.
Hermann Seim Heinz Löster Reiner Claus Hans-Peter Kleber Erich Strack 《Archives of microbiology》1982,132(1):91-95
In view of the development of al-carnitine deficiency, the metabolism ofl-carnitine and structure-related trimethylammonium compounds was studied inSalmonella typhimurium LT2 by means of thin-layer chromatography (TLC).l-Carnitine, crotonobetaine and acetyl-l-carnitine stimulated the anaerobic growth in a complex medium significantly. The stimulation depended on the formation of -butyrobetaine. The reduction ofl-carnitine proceeded in two steps: (1) Dehydration of thel-carnitine to crotonobetaine, (2) hydrogenation of crotonobetaine to -butyrobetaine. The reduction of crotonobetaine was responsible for the growth stimulation. Terminal electron acceptors of the anaerobic respiration such as nitrate and trimethylamine N-oxide, but not fumarate, suppressed the catabolism ofl-carnitine completely. Glucose fermentation, too, inhibited the reduction ofl-carnitine but optimal growth with a high carnitine catabolism was achieved byd-ribose. The esters of carnitine with medium- and long-chain fatty acids inhibited the growth considerably because of their detergent properties.Abbreviations TLC
thin-layer chromatography 相似文献