共查询到20条相似文献，搜索用时 443 毫秒
1.
毕建洪 《商丘师范学院学报》2001,17(2):86-88
近年来，人们对改变开链螯合变电站的末端取代基和链的长度的研究很感兴趣，因为此类螯合剂具有选择螯合金属离子的能力。为此，设计并合成出一种末端为肟基的新型开链聚醚螯合剂：1，7－二（2'－肟甲基苯基）－1，4，7－三氧杂庚烷，采用元素分析、红外光谱、质谱等方法对其结构进行了表征，并较详细地讨论了它的质谱裂解机理。 相似文献
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用水杨醛和丁胺,乙二胺反应合成两种西佛碱,再与TiCl4或FeCl3形成配合物,用红外光谱法,DSC及核磁共振光谱对其结构进行了表征。 相似文献
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本文报导了五个2，6-二甲酰基，4-甲基苯酚（DFMP）与氨基酸生成的西佛碱络合物的合成，并对这些络合物进行了红外、紫外、元素分析等表征分析；同时对两个酮络合做了环电位扫描分析。 相似文献
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金属(Ni、Co、Zn)--Salen配合物的合成及性质研究 总被引：16，自引：0，他引：16
本论述了水杨醛与乙二胺，丙二胺，邻苯二胺，对苯二胺合成西佛碱及西佛碱与Co(Ⅱ），Ni(Ⅱ),Zn(Ⅱ)合成Salen金属配合物，这些化合物均被1HNMR，IR和元素分析证实，并讨论它们的电导，紫外，可见光光谱性质。 相似文献
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合成了6个3－氨基－1－H－1，2，4－三唑的Schiff碱和6个新的5－氨基－1－H－1，2，3，4－四唑的Schiff碱，通过UV、IR、^1H NMR和元素分析等对其结构进行了表征，生物活性测试试验表明，不少化合物都具有良好的植物激素活性，其中Ⅰ系列化合物具有优良的细胞分裂素活性，而Ⅱ系列化合物则具有很好的生长素活性与生根性能。氯代苯甲醛、噻吩甲醛和吲哚甲醛的Schiff碱活性最好。 相似文献
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唐回燕 《岳阳职业技术学院学报》2007,22(4):77-80
α-松油基醚是α-pinene的烷氧基化产物,是一种单萜烯基醚。酸催化单萜烯与脂肪醇的烷氧基化反应得到单萜基醚是合成单萜基醚的一种方法,温度和溶剂都会影响α-松油基醚的生成,合成α-松油基醚的有利条件是:温度为50℃左右,不加溶剂CCl4。 相似文献
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用溶胶－凝胶法获得多孔SiO2载体，浸泡合成法获得不同复合量的PbS/SiO2块材介孔组装体系。研究了复合量、气氛条件及退火及退火温度对其光吸收特性的影响，发现吸收边附复合量和退火温度改变移动，表现出明显的量子尺寸效应。 相似文献
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通过大体积混凝土温度变化机理，给出了大体积混凝土的结构计算温差及温度应力计算的方法；并对温度监测、施工措施进行了探讨．结合工程实例，介绍了某大体积混凝土工程的裂缝控制方法． 相似文献
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《赣南师范学院学报》2021,(3):44-48
采用电弧炉熔炼和急冷快淬吸铸的方法制备Ni-Fe-Ga-X(X=Si, Ge, Al, Co)合金,利用光学显微镜、X射线衍射和示差扫描量热仪,研究了Si, Ge, Al, Co元素合金化对Ni-Fe-Ga合金显微组织、晶体结构和马氏体相变特性的影响.研究结果表明,Si, Ge, Al替代Ga元素后,室温下表现出良好的热弹性马氏体特征,随着其含量增加,合金的马氏体相变特征温度线性下降;而Co替代Ga元素,具有M+γ双相显微组织结构,其相变特征温度随Co含量增加而显著提高.电子浓度和晶胞体积是影响Ni-Fe-Ga-X合金马氏体相变特征温度两个重要的因素.一方面,随着电子浓度的增加,合金的马氏体相变特征温度升高;另一方面,晶胞体积收缩也有利于提高马氏体相变特征温度. 相似文献
11.
通过测定中华常春藤叶片生长期和衰老期的叶长、叶宽、叶面积和有效积温,建立叶片生长和衰老过程的回归方程,并根据方程绘制出对应曲线。经分析发现中华常春藤叶片的叶长优先伸长,并且叶长比叶宽先达到生长最大值,而最大叶长小于最大叶宽;叶片枯萎率随有效积温延续的变化呈J形曲线,而叶片衰老速度变化趋于钟罩型单峰曲线。 相似文献
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通过对中华长尾螺一个周期的解剖观察，可以发现：中华长尾螺的种群结构、感染台湾棘带吸虫的感染率变化具有一定的季节性规律；同时，不同体长组的中华长尾螺其感染率之间存在着一定的差异，体长小于12．0mm的螺，自然条件下几乎不能感染，大于12．0mm的螺，其感染率随体长的增大而升高． 相似文献
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测定了彩石鮒的体长、头长、头宽、头高、吻长、眼后头长、眼径、眼间距、体高、尾柄长、尾柄高、尾鳍长、背鳍基前距、背鳍基长、腹鳍基前距、腹鳍臀鳍间距、体重和去内脏体重.各形态特征变量与体长之间的回归关系显著,相关系数在0.65～0.95之间,所有P＜0.000 1.截距的显著性检验结果在不同变量存在差异,其中头高、吻长、体高、背鳍基长、腹鳍基前距、体重和去内脏体重的截距具有显著的统计学意义,即与零假设(a=0)差异显著(所有P＜0.018),占检测的变量总数的41.18%,其余变量(58.82%)的截距与零假设(a=0)差异不显著(所有P＞0.061).本实验的数据说明比值的数据处理方法在形态学数据的统计分析中的使用需要一个变量之间关系性质的条件检验. 相似文献
14.
Abstract. The main type of phonemic analysis skill considered to affect spelling acquisition has been awareness of phoneme quality. However, it is also important to find out whether other measures of phoneme awareness might contribute to literacy acquisition. Thus, the influence of phoneme length and phoneme quality awareness on spelling in Finnish was compared. The Oddity task was used to assess phonemic awareness and spelling skills were investigated by a spelling-to-dictation task. The results showed that length awareness predicted spelling better than quality awareness did. Moreover, length awareness was more strongly related to spelling of long phonemes, which specifically require analysis of phoneme length, than to spelling of phoneme clusters not involving length analysis. Additionally, only length awareness predicted children's general spelling skills. These findings suggest that awareness of length, which is a phonemic attribute of the Finnish language, is connected to children's spelling skills more strongly than awareness of phoneme quality is. 相似文献
15.
A novel experimental method, shift-rate recovery, was developed and used in a series of three experiments. These examined the extent to which 6-month-old infants (N = 131) find perceptual cues such as density and length useful in the discrimination of linearly arranged sets containing large numbers of objects. Results showed that infants discriminated between arrays that differ in number and density, with length held constant, when the arrays were presented either simultaneously or successively. On the other hand, infants discriminated only between arrays that differ in number and length, with density held constant, when the arrays were presented simultaneously. Infants were, however, able to perform a successive length discrimination when the arrays were continuous rather than consisting of discrete items. These findings support the conclusion that infants are able to discriminate between large number sets by relying on absolute cues such as density (but not length) and on relative cues such as optical one-to-one correspondence. 相似文献
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Genotypic and environmental contributions to the defensive burying response were examined by testing four sublines of two inbred strains of mice in test chambers of three different lengths. Burying was found to be dependent on both the particular subline tested and the length of the test chamber employed. For two sublines, specific increases in the length of the test chamber resulted in the complete abolition of defensive burying. A third subline never displayed defensive burying, and the fourth buried in all three chamber-length conditions. Sex differences in burying were never observed. Rather than being viewed as a species-specific defensive reaction, it was proposed that defensive burying should more appropriately be viewed as a genotypically dependent response, the expression of which is contingent on the specific environmental context in which an aversive stimulus is encountered. Apparent conflicts in the defensive-burying literature were reconciled in accordance with this interpretation. 相似文献
18.
Theoretical relationships between first flush of roof runoff and influencing factors 总被引：1，自引：0，他引：1
Considering the short length of building roofs, a theoretical analysis of the first flush of roof runoff was conducted based on the kinematic wave and pollutant erosion equations. This mathematical derivation with analytical solutions predicts pollutant mass first flush （MFF）, mean concentration of initial runoff （MCIF）, mean concentration of roof runoff （MCRR） with diversion of initial portion and residual mass available on the bed surface （RS） after the entire runoff under the condition of constant excess rainfall. And the effects of the associated influencing factors （roof length, roof gradient, roof surface roughness, rainfall intensity, rainfall duration, and erosion coefficients） on them were discussed while the values of parameters referred to the previous studies. The results showed that for roofs whose length is shorter than 20 m, both the increase in roof length and roof gradient and the decrease in roof surface roughness result in larger MFF and MCIF and smaller MCRR and RS, which is beneficial to water reuse and pollution reduction. The theoretical relationship between the first flush and the influencing factors may aid the planning and design of roof in terms of rainwater utilization or diffuse pollution control. 相似文献
19.
Some previous studies of visual word recognition have reported an interaction between visual field and word length (measured by number of letters), such that recognition is affected more by word length for words presented in the left than for words presented in the right visual field. However, when manipulating serial position of letters in words to measure length effects, there are also reports of symmetrical word length effects in the two visual fields. Here we report two experiments, presenting four‐ and seven‐letter words, suggesting that the serial position and length effects in the hemispheres are separable and task dependent. For tasks that rely more heavily on letter‐level processing such as letter search (Experiment 1), performance in both hemifields showed similar effects of serial position; however, when comparing four‐ and seven‐letter words, an effect of word length was evident only in the left visual field, in line with the well‐established interaction between word length and hemifield. An interaction between word length and hemifield was confirmed for the same stimuli when they were employed in a lexical decision task, which forced whole‐word processing (Experiment 2). We conclude that the effects of serial position and number of letters in the two visual fields are separable, and are selectively affected by task type. 相似文献
20.
本文给出了基于红外和单片机用于超长物体长度测量的电路设计和信号处理,可用于需要长度测量的不同系统中. 相似文献