共查询到20条相似文献,搜索用时 31 毫秒
1.
2.
黑曲霉G2.1.1.1.4菌株在产生植酸酶时受无机磷的反馈阻遏,并且植酸酶的产生与淀粉酶的产生存在相互抑制。对植酸酶固体发酵进行调控和通过响应面分析优化发酵条件,提高了植酸酶产量。最适发酵条件下,植酸酶(PhytA)的产量可达62.1u/g.干基。 相似文献
3.
4.
5.
6.
用光镜和扫描电镜观察鞋形共系蚤Syngenopsyllus calceatus (Rothochild)、无值大锥蚤Macrostylophora euteles (Jordan et Rothschiold)和不等单蚤Monopsyllus anisus(Rothechild)的阳茎体侧面、背面和腹面。其中三种蚤阳茎体的背、腹面和无值大锥蚤阳茎体的侧面形态结构是首次报道。鞋形共系蚤有一对明显的阳茎囊突和一对与其相连的"c-骨片", 首次报道该蚤具有前距。无值大锥蚤具一对“茄形骨片”,阳茎钩突末端分为长而宽的腹叶和短而末端尖的背叶,阳茎内突后半部分特化为“后阳茎内突”。三种蚤的钩突桩略呈牛角形,由后弯向前。三种蚤阳茎体的形态结构差异显著,指出了它们是分类上值得注意的特征。认为交配时阳茎杆只在一定范围内作定向滑动。将阳茎体从蚤体内解剖出来,并且观察其背腹面,有助于清晰、完整和准确地观察其形态结构。 相似文献
7.
8.
研究证明Paracarinachitids的外骨骼都不是由8个骨板组成,骨片具有清楚的微层构造,表明它们是由叠覆的生长层组成,每个生长节上有一个小刺,在顶端下侧面前端都有肾形缺凹。同一标本上存在顶端部的融合和远顶端部的分节彼此递交的现象表明这种表象上的差异是后期次生磷灰石包裹或腐蚀的结果;其下侧缘融合和下侧面无缝隙的现象说明将Paracarinachites spinus的骨片分成头板、中间板和尾板是没有根据的。骨片表面存在的针状体是成岩作用的产物,它是粘土矿物和磷酸盐针状结晶体而不是多板纲的骨针。凡此强有力地说明Yangtzechiton是Paracarinachites的晚出同义名。根据形态功能、组织结构,特别是叠覆状排列的骨片和孤立的生长节等特征,paracarinachitids 可能与zhijinitids有密切关系,但两者是否同源尚缺少进一步的证据、据此,笔者认为将paracarinachitids 暂置于分类位置未定的具骨片后生动物较妥。 相似文献
9.
10.
11.
12.
13.
论地生态学 总被引:24,自引:0,他引:24
生态学发展到目前已形成一系列的分科,它已不是一门单独的学科,而是一组学科-学科的体系。名称中包含“生态”二字的学科至少在一百个以上,因而,产生了如何对大量生态学科进行分类的问题。 我们认为,如果根据研究对象的性质和尺度(规模)以及相应地需要采用的研究方法的特点,并考虑当前发展的趋势,可以把生态学概括为3类:生物生态学、地生态学和全球生态学。 从当前趋势看,至少下列8个问题是地生态学注意的核心:(1)人工生态系统;(2)生物(主要是植物)指示现象;(3)地生态制图;(4)生态监测;(5)生态预测;(6)生态区划;(7)生态规划与设计;(8)生态影响评价。 相似文献
14.
This article discusses the background, mechanism and need for warm‐up before performing difference tests while aspects of the methodology are illustrated with examples. 相似文献
15.
1. Every hemochromogen consists of the iron pyrrol complex, reduced heme, combined with some nitrogenous substance. 2. In every hemochromogen there is the equilibrium: Hemochromogen ⇄ Reduced heme + Nitrogenous substance. 3. Cyanide can form two distinct compounds with reduced heme, one of which is the typical hemochromogen, cyan-hemochromogen. 4. Reduced heme in alkaline solution has a great affinity for cyanide. 5. Cyan-hemochromogen probably contains one cyanide group per heme. 6. The hemochromogen prepared from hemoglobin is a compound of denatured globin and reduced heme. 7. The individual molecule of denatured globin, of hypothetical molecular weight 16,700, can convert at least 10 molecules of reduced heme into hemochromogen. 8. The hemochromogen-forming capacity of globin is, under given conditions, greater than that of edestin, which in turn, is greater than that of zein. 相似文献
16.
17.
18.
20.
ON OUTGROUPS 总被引:3,自引:1,他引:2
Kevin C. Nixon James M. Carpenter 《Cladistics : the international journal of the Willi Hennig Society》1993,9(4):413-426
Abstract— The relations among polarity, outgroups and rooting are clarified. The "outgroup algorithm" and "outgroup substitution method" are irrelevant forms of relaxed parsimony. They should be discarded in favor of unconstrained, simultaneous analysis of all terminals. A revised outgroup method is described both in text and with a computer-generated flowchart. Lundberg rooting is consistent with cladistic parsimony only under specific circumstances involving hypothetical ancestors.
"Both sides seemed convinced that the 'real enemy'is a vicious conspiracy of some kind."
Hunter S. Thompson (1979: 145). 相似文献
"Both sides seemed convinced that the 'real enemy'is a vicious conspiracy of some kind."
Hunter S. Thompson (1979: 145). 相似文献