共查询到20条相似文献,搜索用时 15 毫秒
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图论在中国慈姑属数量分类研究中的应用 总被引:1,自引:0,他引:1
.黄德世;.钟扬;.陈家宽 《武汉植物学研究》1988,6(4):405-406
慈姑属(Sagittaria L.)是水生单子叶植物泽泻科(Alismataceae)的一个重要属。近年来,陈家宽等对中国慈姑属进行了系统研究。作者应用聚类分析和主成分分析进行了中国慈姑属的数量分类,取得了良好的效果。由于慈姑属分类性状数目较大,因而在压缩后的三维空间中描述分类群间的距离, 相似文献
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兰州北山三种蜥蜴春季食性分析 总被引:10,自引:1,他引:9
兰州地区密点麻蜥、丽斑麻蜥和草原沙蜥的春季食物均为动物食物。无论在栖息地重叠地区还是非重叠地区,三种蜥蜴的食物种类在种间均无显著差异(F=0.861,dfT=2,dfE=36,P〉0.05)。种内不同性别和年龄食性无显著差异。 相似文献
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A. E. Mirsky 《The Journal of general physiology》1936,19(4):571-575
1. When myosin is exposed to a typical denaturing agent (acid) it becomes insoluble and its SH groups are activated. 2. The same number of active SH groups is found in the soluble myosin of resting muscle as in the insoluble myosin of muscle in rigor. No activation of SH groups accompanies the formation of insoluble protein in rigor. 3. When the insoluble myosin of muscle in rigor is treated with a denaturing agent its SH groups are activated. 4. Protein coagulation as brought about by denaturing agents (heat, acid, alkali, alcohol, urea, salicylate, surface forces, ultraviolet light) is a distinctly different change from the coagulation of myosin brought about by the unknown agent in muscle. 相似文献
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Wood with cambium of Plumeria rubra Linn. was cultured in modified Schenk and Hildebrandt medium for 75 days. Change in dimension and frequency of cells was compared with that grown in situ for 75 days. Feeding of 41% sucrose in vitro brought about the same type of differentiation as occurred in situ , where non-reducing sugar percentage increased (from 0.0004 before culture to 0.0032 after 75 days' growth in situ ). Sucrose favoured enlargement of axial elements and numerical increase of all lignified elements. 相似文献
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原位杂交和原位PCR技术在鱼类基因定位中的应用 总被引:5,自引:0,他引:5
染色体原位杂交( in situ hybridization, ISH)是基因物理定位的主要方法之一,它根据核酸分子碱基互补配对的原理,将标记的外源核酸探针与染色体上变性处理后的单链DNA互补配对,再经检测而将靶顺序在染色体上的位置显示出来。 原位PCR技术是将原位杂交与PCR技术有机的结合,在原位扩增目的DNA片段,并在原位检测其扩增产物,因而兼有PCR及原位杂交技术二者的优越性:既可以同时获得组织及细胞的形态结构信息与分子信息,进行定性、定位分析,又具有比原位杂交更好的敏感性与专一性。 染色体原位… 相似文献
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中国二十个省、自治区蝽科昆虫种数比较 总被引:1,自引:0,他引:1
从广泛和长期的采集工作中可以体会到:南方昆虫种类多,北方昆虫种类少;植被丰茂的地方昆虫种类多,植被贫乏的地方昆虫种类少。但我国各省、区的昆虫种数,多的究竟多到什么程度,少的究竟少到什么程度,却始终没有见到一个具体的数据,足资比较说明。下面选取对蝽科昆虫采集工作做得比较细致的20个省、区,代表国内不同方位及生态类型,列出每一省、区所采蝽科及各亚科的种数,供分析比较。 观表1,知参加比较的蝽科昆中计共389种,其中属于盾蝽亚科44种,荔蝽亚科24种,兜蝽亚科15种,短喙蝽亚科16种,益蝽亚科46种,蝽亚科244种。这个数字,与1935年胡经甫教授编写的《中国昆虫名录》所列蝽科301种及1977年肖采瑜教授等编著的《中国蝽类昆虫鉴定手册》第一册所列蝽科 相似文献
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福建和溪亚热带雨林凋落物营养元素动态 总被引:15,自引:0,他引:15
探讨了福建和溪亚热带雨林主要营养元素通过凋落物的归还动态.结果表明,该森林一年中凋落物不同组分各元素的含量具有波动性,加权平均含量为N>K>Ca>Mg>P(落果Ca=Mg、落枝Ca>K)。通过凋落物归还N、P、K、Ca、Mg元素的年库流量,分别为87.41、3.82、40.80、28.81和15.32kghm(-2),灰分量为284.57kghm(-2),其中以落叶形式居最大,分别各占总量的73.4%、68.1%、.77.2%、72.9%、74.5%和79.9%;各元素的年库流量与年凋落物量的月分布相一致,有明显的季节性.森林地表残留物N、P、K、Ca、Mg元素的累积储量.分别为54.83、2.45、9.69、17.0和9.25kghm(-2).五种元素在林下地表的滞留时间,分别为N0.61、P0.61、K0.23、Ca0.56和Mg0.53年. 相似文献
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Various nitrogen sources were shown to alter the growth and modify nitrate reductase activities of stem callus tissue derived from two clones of Convolvulus arvensis L. (field bindweed). Callus from a Washington (S) clone grew better and had a higher level of nitrate reductase activity than callus from a New Mexico (R) clone when nitrate was the only source of nitrogen available in the culture medium. The addition of glycine to the culture medium decreased growth of the R clone and increased growth of the S clone, but glutamic acid repressed growth of both clones. An amide source of nitrogen such as glutamine or asparagine, or ammonium was required to produce maximum growth of both bindweed clones. Glutamine increased nitrate reductase activity in the two clones, and glycine increased nitrate reductase activity in the S clone but decreased it in the R clone. Glutamic acid decreased nitrate reductase activities in both the R and S tissues. 相似文献