菠菜、葱与豆腐可否一起吃的实验探究

通过探究菠菜、葱与豆腐是否可以一起吃,使学生深刻理解化学与生活的密切联系。分别检验菠菜、葱中的钙、铁、镁和草酸;检验豆腐中的钙、铁、镁;菠菜与葱中草酸能否与豆腐中的钙生成不溶性草酸钙。     

两种葱属植物提取物对香蕉枯萎病菌有抑制作用组分的气相色谱-质谱分析

以葱、韭菜根的石油醚和乙酸乙酯提取物对香蕉枯萎病菌进行了抑菌实验,结果表明:葱茎的石油醚提取液对香蕉枯萎病菌的抑制效果最明显,采用气相色谱-质谱法对葱茎的石油醚提取液进行分析,发现其中含有42.07％的二硫化物和16.29％的噻烷类化合物,推断这2种化学成分可能是抑菌的主要成分.进一步对葱的根、茎、叶和韭菜根的石油醚提...     

多层碳纳米球的研究

用弧光放电法制备了碳的巴基葱.用原子力显微镜（AFM）、扫描隧道显微镜（STM）和透射电镜（TEM）研究了在高定向石墨(HOPG)和金(Au)基底上的巴基葱的行为和电学特性.扫描隧道谱表明,巴基葱的电学特性具有与单壁碳纳米管相似的非线性特性.较小尺寸的巴基葱呈半导体特性,尺寸增大倾向金属线性.AFM/STM图像显示,在HOPG和Au基底上的巴基葱能够聚集成二聚体.利用较小尺寸巴基葱的电学非线性特性,有希望构造纳米电子学的单电子器件.     

镧对青菜生物量、植株氮磷钾含量及土壤酶活性的影响

利用盆栽试验,研究了镧对青菜生物量、植株氮磷钾含量及土壤酶活性的影响.结果表明,施用镧显著增加了青菜生物量,与对照相比地上部干重提高了5.49%～19.78%,根干重提高了13.51%～51.35%.在低浓度下,随镧浓度的升高,青菜茎叶和根的氮、磷、钾含量逐渐增加,到一定浓度后,随着镧浓度的继续升高,含量反而逐渐降低.镧施入土壤后对脲酶、酸性磷酸酶、转化酶活性表现出刺激作用并随浓度的升高而增强,而对过氧化氢酶活性有轻微的抑制作用,对脱氢酶活性有强烈的抑制作用.     

腌制咸鱼中亚硝酸盐测定和清除方法研究

建立了一种检测咸鱼中亚硝酸盐含量的分光光度法。方法原理是亚硝酸盐与对氨基苯磺酸重氮化,再与N,N-二乙基苯胺偶联生成橙色产物,该产物在474nm处有最大吸收。在最佳实验条件下,亚硝酸根的浓度在0~10mg·L~(-1)范围内成良好的线性关系,回收率为89%~92%。该方法测定咸鱼中亚硝酸盐的含量简单、快速、灵敏高,干扰小,测定结果与国标法基本一致。同时对咸鱼中亚硝酸盐的去除方法进行了研究,考察了超声提取葱、姜、蒜提取液及三者的混合提取液对亚硝酸盐的清除作用。结果表明:物料比分别为50g/100g、30g/100g、30g/100g葱、姜、蒜在60℃下,超声40min的后的提取液对亚硝酸盐清除效果最好,蒜、姜、葱的清除率分别为63.6%,56.6%,54.6%。蒜含量不小于50%的蒜、葱、姜混合浸提液对亚硝酸盐的清除效果优于纯的葱、姜、蒜。且葱、姜、蒜提取液的比例为1:4:5时清除率最高。不同腌制时间的咸带鱼经过混合浸提液浸泡后,去除率在69.8%~95.5%范围内,清除效果很好。     

分子篩(制备、性质与应用)

引言吸附剂的吸附性质主要与其化学本性、表面积大小、結构及小孔(按其有效半径)的分布有关。决定吸附量的吸附势可以在显著程度上随內表面的几何形状而变。在公子大小的窄小孔隙或縫隙中,由于相对面孔壁声的迭加,吸附势有显著增加。吸附剂的孔隙愈小,这个效应就愈强烈。吸附剂的可以达到的吸附面积也与被吸附物质的分子大小有关,一部     

藏药鸦葱化学成分的研究

鸦葱(Scorzonera austriaca)系菊科(Compositae)鸦葱属植物,多年生草本.该属植物我国约有23种,主要分布于东北、华北及西北部分省区.鸦葱在民间作为传统藏药(藏名:巴多拉),全草入药,可消肿解毒、治五痨七伤、疔疮痈肿、乳腺炎等;在许多国家和地区又作为蔬菜食品、牧草、蚕饲料等.     

稀土元素对螺旋藻生长、光合和放氢作用的影响

稀土元素对钝顶螺旋藻的光合作用和氢酶催化放氢活性有程度不同的影响。钕对藻体光合放氧速率的促进作用最为明显,镧强烈促进~(14)CO_2光合掺入藻体的速率,镧、铈和钕对藻体的生长及其氢酶催化放氢作用有明显的促进。但各种元素作用的最适浓度不同。     

二元蒽化合物的光诱导分子内电子转移与电荷分离

本文设计合成了一系列共扼型与非共扼型含葱的电子给体与电子受体化合物,通过介质的极性、温度、粘度、荧光寿命等对它们的光物理行为作了较为系统的研究,特别是分子的结构,构象与化合物发光行为的关系,得到了一些十分有意义的结果。     

催化动力学光度法测定痕量对苯二胺

<正>对苯二胺是一种重要的化工原料,常用作偶氮染料和硫化染料的中间体,也是合成染发剂中的主要成份,因其对人体有强烈的致敏作用,染发剂中最高允许含量为6%。同时对苯二胺也是国际公认的一种致癌物,随着化工工业的迅速发展,对苯二胺的废水排放量日益增加,严重污染了环境,也危害着人体健康。     

Characterization of Key Odorants in Scallion Pancake and Investigation on Their Changes during Storage

To characterize key odorants in scallion pancake (SP), volatiles were extracted by solvent extraction-solvent assisted flavor evaporation. A total of 51 odor-active compounds were identified by gas chromatography-olfactometry (GC-O) and chromatography–mass spectrometry (GC-MS). (Z/E)-3,6-Diethyl-1,2,4,5-tetrathiane was detected for the first time in scallion food. Application of aroma extract dilution analysis to extracts showed maltol, methyl propyl disulfide, dipropyl disulfide and 2-pentylfuran had the highest flavor dilution (FD) factor of 4096. Twenty-three odorants with FD factors ≥ 8 were quantitated, and their odor active values (OAVs) were calculated. Ten compounds with OAVs ≥ 1 were determined as the key odorants; a recombinate model prepared from the key odorants, including (E,E)-2,4-decadienal, dimethyl trisulfide, methyl propyl disulfide, hexanal, dipropyl trisulfide, maltol, acetoin, 2-methylnaphthalene, 2-pentylfuran and 2(5H)-furanone, successfully simulated the overall aroma profile of SP. The changes in odorants during storage were investigated further. With increasing concentrations and OAVs during storage, hexanal became an off-flavor compound.     

气相色谱/质谱法分析曼陀罗果实挥发油的化学成分

用水蒸汽蒸馏法从曼陀罗果实中提取挥发油,并用气相色谱/质谱(GC/MS)联用技术对其化学成分进行分离和结构鉴定,用峰面积归一化法确定各成分的相对含量。结果确定了68种化合物,占挥发油总量的82.83%,其主要成分为6-戊基-5,6-二氢化吡喃-2-酮(9.13%)、3,7,11,15-四甲基-2-十六碳烯-1-醇(6.71%)、二苯酮(6.16%)和1-己醇(6.10%)等。     

Chemical composition and antimicrobial activity of the volatile oil from Fusarium tricinctum, the endophytic fungus in Paris polyphylla var. yunnanensis

The volatile oil, obtained by hydro-distillation from Fusarium tricinctum, the endophytic fungus isolated from Paris polyphylla var. yunnanensis, was analyzed by gas chromatography-mass spectrometry (GC-MS). trans-1,2,3,3a,4,7a-Hexahydro-7a-methyl-5H-inden-5-one (73.1%), 2-methylene-4,8,8-trimethyl-4-vinyl bicyclo [5.2.0] nonane (12.0%), and 2,6-dimethyl-6-(4-methyl-3-pentenyl) bicyclo [3.1.1] hept-2-ene (4.5%) were the major compounds of the 15 identified components accounting for 95.4% of the volatile oil. The antimicrobial activity of the volatile oil was assayed against eight bacteria and two fungi. The minimum inhibitory concentration (MIC) values of the volatile oil against the test bacteria ranged from 25 to 45 microg/mL. The MIC values against the fungi Candida albicans and Magnaporthe oryzae were 100 and 225 microg/mL, respectively. The mean inhibitory concentration (IC50) values of the volatile oil against the test bacteria ranged from 17.8 to 31.6 microg/mL, and those of the volatile oil against C. albicans and M. oryzae were 84.3 and 204.3 microg/mL, respectively.     

Quantitative determination of S-alk(en)ylcysteine-S-oxides by micellar electrokinetic capillary chromatography

A novel method for determination of S-alk(en)ylcysteine-S-oxides by capillary electrophoresis has been developed and validated. The method is based on extraction of these sulfur amino acids by methanol, their derivatization by fluorenylmethyl chloroformate and subsequent separation by micellar electrokinetic capillary chromatography. Main advantages of the new method are simplicity, sensitivity, high specificity and very low running costs, making it suitable for routine analysis of a large number of samples. Employing this method, the content of S-alk(en)ylcysteine-S-oxides was determined in 12 commonly consumed alliaceous and cruciferous vegetables (e.g. garlic, onion, leek, chive, cabbage, radish, cauliflower and broccoli). The total content of these amino acids in the Allium species evaluated varied between 0.59 and 12.3mg g(-1) fresh weight. Whereas alliin was found only in garlic, isoalliin was the major S-alk(en)ylcysteine-S-oxide in onion, leek, chive and shallot. On the other hand, the cruciferous species analyzed contained only methiin in the range of 0.06-2.45mg g(-1) fresh weight.     

气相色谱-质谱法测定姜黄挥发油化学成分

采用水蒸气蒸馏法提取姜黄挥发油,用气相色谱－质谱联用技术分离和鉴定姜黄挥发油的化学成分。经计算机ＮＢＳ谱库检索,发现姜黄挥发油中至少有１５个峰,鉴定出α－姜黄烯、α－姜烯、桉叶油素和球姜酮等１５种组分;另外还有１－（３－环戊基醛）－２,４－二甲基苯、β－倍半水芹烯、大根香叶酮、大根香叶烷、顺双环［３,３,１］酮－２－烯－９－醇等成分。姜黄挥发油中主要成分为α－姜黄烯。     

大叶黄杨叶、茎、果挥发油成分及抗病毒作用

研究了大叶黄杨叶、茎、果挥发油的化学成分及抗病毒活性。 采用超临界二氧化碳萃取,应用气相色谱-质谱联用(GC-MS) 法鉴定挥发油化学成分,考察体外抗病毒作用。 共鉴定133个化合物,大叶黄杨叶挥发油中主要有2-乙氧丙烷(41.92%)、(E)-2-己烯-1-醇(17.8%)、 (E)-香叶醇(7.86%)、甲基环己烷(6.60%)等;大叶黄杨茎挥发油中主要有甲氧基苯基肟(33.10%)、二十八烷(14.34%)、α-甲基-α-[4-甲基-3-戊烯基]环氧乙烷甲醇(12.48%)、甲苯(11.88%)、二十一烷(7.74%) 等;大叶黄杨果挥发油中主要有苯甲醛(15.52%)、甲苯(15.03%)、甲基环己烷(14.76%)、(Z)-3-己烯-1-醇(10.98%)等。 大叶黄杨叶、茎、果的环己烷、乙醚萃取挥发油对特定病毒有显著抑制效果。 大叶黄杨叶、茎、果中挥发油萃取部位成分差异明显,有特定抗病毒活性。     

佩兰挥发性化学成分的固相微萃取研究

采用固相微萃取-气相色谱-质谱法分析佩兰中挥发性化学成分,共分离出84个组分,并鉴定了67个组分,用归一化法测定其质量分数,占总挥发性组分峰面积的98.05%。主要成分是对-伞花烃(5.19%)、芳樟醇(3.72%)、β-石竹烯(12.35%)、α-律草烯(13.39%)、α-姜黄烯(2.11%)、(-)-石竹烯氧化物(8.25%)、. /-.-4-乙酰基-1-甲基环己烯(8.91%)。     

三种丁香花精油的挥发性成分比较分析

为了解紫丁香、白丁香和红丁香花蕾精油样品挥发性成分的差异,采用气相色谱-质谱联用技术（GC-MS）分析了三种丁香花精油样品的挥发性成分,并对三者的挥发性成分进行了主成分分析和聚类分析。结果从紫丁香、白丁香和红丁香精油中分别解析出46、64和56种挥发性物质,包括烷烃类、酯类、醇类、酮类、烯烃类、酚类、有机酸等,其中共有的挥发性成分为9种。三种丁香花精油样品的挥发性成分比较分析显示,酯类是含量最高的挥发性成分,其次是烷烃类,并且这两类物质在不同品种的丁香花精油中含量不同。统计分析结果表明三种样品的挥发性成分之间没有明显差别。本研究为增加丁香花精油的应用范围提供了理论依据。     

New procedure for the control of the treatment of industrial effluents to remove volatile organosulfur compounds

We present a new procedure for the determination of volatile organosulfur compounds in samples of industrial effluents using dispersive liquid–liquid microextraction and gas chromatography with flame photometric detection. Initially, the extraction parameters were optimized. These included: type and volume of extraction solvent, volume of disperser solvent, salting out effect, pH, time and speed of centrifugation as well as extraction time. The procedure was validated for 30 compounds. The developed procedure has low detection limits of 0.0071–0.49 μg/L and a good precision (relative standard deviation values of 1.2–5.0 and 0.6–4.1% at concentrations of 1 and 10 μg/L, respectively). The procedure was used to determine the content of volatile organosulfur compounds in samples of effluents from the production of bitumens before and after chemical treatment, in which six compounds were identified, including 2‐mercaptoethanol, thiophenol, thioanisole, dipropyl disulfide, 1‐decanethiol, and phenyl isothiocyanate at concentrations ranging from 0.47 to 8.89 μg/L. Problems in the determination of organosulfur compounds related to considerable changes in composition of the effluents, increase in concentration of individual compounds and appearance of secondary pollutants during effluent treatment processes are also discussed.     

超临界流体萃取-GC-MS分析西黄丸中挥发性成分

建立西黄丸中挥发油成分乙酸辛酯的含量测定方法,为西黄丸的质控标准提供依据。方法:超临界CO2萃取西黄丸中挥发油成分,采用气相色谱法测定乙酸辛酯含量;研究压力、温度、时间和粒度因素对挥发油得率与乙酸辛酯含量的影响,并进行了化学计量学分析。采用GC-MS分析了适宜条件的挥发油的成分。综合考虑挥发油得率和乙酸辛酯含量双指标,确定的西黄丸挥发油萃取条件为:粉碎粒度为80目,萃取压力为25 MPa,温度为40℃,时间为2 h。在此条件下,挥发油得率达到7.76%,乙酸辛酯含量达到0.72 mg·g^-1。通过指纹图谱、主成分分析(PCA)、正交偏最小二乘判别分析(OPLS-DA)化学计量学分析可知,不同萃取条件对所提取的挥发油物质组分及其含量没有显著性差异。GC-MS鉴定出的主要成分有(1S-endo)-2-甲基-3-亚甲基-2-(4-甲基-3--3-戊烯基)-二环[2.2.1庚烷、10α-羟基日本刺参萜、(±)-麝香酮、4-亚甲基-2,8,8-三甲基-2-乙烯基-双环[5.2.0]壬烷和2-甲基-4-(2,6,6-三甲基-1-环己烯-1-基)丁醛。结论:西黄丸挥发油成分适宜萃取条件,及建立的乙酸辛酯含量测定方法准确、可靠,为有效控制西黄丸质量,完善其质量标准及进一步的药效成分研究提供了科学依据。