共查询到20条相似文献，搜索用时 38 毫秒
1.
以乙醚为改性剂,采用超临界CO2萃取法提取中药蛇床子的有效成分,并用GC／MS法对其化学成分和相对含量进行了分析．结果表明,与水蒸气蒸馏法比较,超临界CO2萃取法的产率较高,总萃取率为8．46％(w),蒸馏法提取蛇床子挥发油的产率较低,仅为1．01％(w);蛇床子超临界萃取物中香豆素类的相对含量约为67．63％,其蛇床子素相对含量占总香豆素的78．92％,而蒸馏法提取的挥发油中鉴定出一种香豆素成分,其相对含量仅为1．65％．因此,超临界CO2萃取法可以有效提取中药蛇床子的多种香豆素类成分,其方法为其他同类中药的开发和药学鉴定提供了参考依据． 相似文献
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Lin Huang Xian-yong Ma Zong-yong Jiang You-jun Hu Chun-tian Zheng Xue-fen Yang Li Wang Kai-guo Gao 《Journal of Zhejiang University. Science. B》2016,17(12):965-974
To investigate the effect of glycitein, a synthetic soybean isoflavone (ISF), on the intestinal antioxidant capacity, morphology, and cytokine content in young piglets fed oxidized fish oil, 72 4-d-old male piglets were assigned to three treatments. The control group was fed a basal diet containing fresh fish oil, and the other two groups received the same diet except for the substitution with the same dosage of oxidized fish oil alone or with ISF (oxidized fish oil plus ISF). After 21 d of feeding, supplementation of oxidized fish oil increased the levels of malondialdehyde (MDA), oxidized glutathione (GSSG), interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), interleukin-2 (IL-2), nuclear factor κ B (NF-κB), inducible nitric oxide synthase (iNOS), NO, and Caspase-3 in jejunal mucosa, and decreased the villous height in duodenum and the levels of secretory immunoglobulin A (sIgA) and IL-4 in the jejunal mucosa compared with supplementation with fresh oil. The addition of oxidized fish oil plus ISF partially alleviated this negative effect. The addition of oxidized fish oil plus ISF increased the villous height and levels of sIgA and IL-4 in jejunal mucosa, but decreased the levels of IL-1β and IL-2 in jejunal mucosa (P<0.05) compared with oxidized fish oil. Collectively, these results show that dietary supplementation of ISF could partly alleviate the negative effect of oxidized fish oil by improving the intestinal morphology as well as the antioxidant capacity and immune function in young piglets. 相似文献
3.
采用皂化法、荧光法、色谱法以及红外光谱法对食用油中掺入矿物油的鉴别、分离和分析方法进行了研究,方法具有样品用量小、快速、准确度高的特点,适用于食用油中是否掺加工业矿物油的分析. 相似文献
4.
Rowland Monday Ojo Kayode Anthony Jide Afolayan 《Journal of Zhejiang University. Science. B》2015,16(8):680-689
Renewed interest in natural materials as food flavors and preservatives has led to the search for suitable essential oils. Moringa oleifera seed essential oil was extracted by solvent-free microwave and hydrodistillation. This study assessed its chemical constituents. Cytotoxicity of the oils was investigated using hatchability and lethality tests on brine shrimps. A total of 16 and 26 compounds were isolated from the hydrodistillation extraction (HDE) and solvent-free microwave extraction (SME) oils, respectively, which accounted for 97.515% and 97.816% of total identifiable constituents, respectively. At 24 h when the most eggs had hatched, values of the SME (56.7%) and HDE (60.0%) oils were significantly different (P<0.05) from those of sea water (63.3%) and chloramphenicol (15.0%). Larva lethality was different significantly (P<0.05) between HDE and SME oils at different concentrations and incubation periods. The median lethal concentration (LC50) of the oils was >1000 mg/ml recommended as an index for non-toxicity, which gives the oil advantage over some antioxidant, antimicrobial, therapeutic, and preservative chemicals. 相似文献
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Identifying Science Teachers’ Perceptions of Technological Pedagogical and Content Knowledge (TPACK)
Tzu-Chiang Lin Chin-Chung Tsai Ching Sing Chai Min-Hsien Lee 《Journal of Science Education and Technology》2013,22(3):325-336
The application of information and communication technology in instruction is highly emphasized in the contemporary education of science teachers. This paper hence aims to explore science teachers’ perceptions of technological pedagogical content knowledge (TPACK) addressing teachers’ perceptions of the affordances of technology application in instruction. A total of 222 pre- and in-service science teachers in Singapore were surveyed. Structural equation models analysis was utilized to examine the model of TPACK involving the seven factors of technological knowledge (TK), pedagogical knowledge (PK), content knowledge (CK), technological content knowledge (TCK), technological pedagogical knowledge (TPK), pedagogical content knowledge (PCK), as well as synthesized knowledge of technology, pedagogy, and content (TPC). The results confirm the seven-factor model and indicate that the science teachers’ perceived TPC significantly and positively correlated with all the other TPACK factors. This paper further reveals the relationships between the science teachers’ perceptions of TPACK and their demographic characteristics such as teaching experience, gender, and age. The findings indicate that female science teachers perceive higher self-confidence in pedagogical knowledge but lower self-confidence in technological knowledge than males. Further, female in-service science teachers’ perceptions of TK, TPK, TCK, and TPC significantly and negatively correlate with their age. 相似文献
7.
气相色谱法测定芝麻油掺伪的研究 总被引：3，自引：0，他引：3
采用气相色谱法去芝麻油掺伪进行定性和定量分析，以芝麻油中掺入其他油品后测定其主要脂肪酸含量及分布的变化，建立掺伪芝麻油的数据库，从中找出规律，作为研究芝麻油中掺伪定性依据和定量计算方法。 相似文献
8.
Jordan Smith Derek Hanson Shannon N. Fanning Sara Doan 《Technical Communication Quarterly》2016,25(4):260-277
The authors examined a corpus of figure captions from technical and professional communication (TPC)-journal articles to test their sense that TPC captions do not fulfill their communicative potential as well as, they sensed, journals in science often do. The authors performed a content analysis on captions from biology-journal articles and iteratively tested a coding scheme of caption content. The resulting scheme can help in analyzing caption content, developing captions, and imparting a variety of TPC-related skills to students. 相似文献
9.
ABSTRACT Civil Society Organizations (CSO) can improve their effectiveness and add measurable value to society by using a megaplanning approach as the guiding criteria for their organizational planning. This article shows how Asociación Conciencia, a leading Argentinean CSO, has used megaplanning to clarify its vision, mission, align its goals and programs and update its mission and programs over more than twenty years of critical social changes in Argentina. 相似文献
10.
Microcapsules of volatile oil containing Herba Schizonepetae(VOHS) were prepared by emulsion solvent diffusion method to improve the drug loading and reduce the amount of pharmaceutical excipients.Orthogonal assay was applied to optimize the preparation condition of microcapsulation,and the results illustrated that the ratio of ethyl cellulose(EC) to VOHS influenced the property of VOHS microcapsule significantly.GC-MS analysis indicated that some volatile components with low concentration in VOHS were lost after microencapsulation.The microcapsules prepared with optimum condition had good fluidity,and the holes on the surface of the microcapsules contributed to the release of VOHS.The particles of the microcapsule conformed to a normal distribution with the diameter of 45—220 μm.In the simulated intestinal fluid containing 0.2% sodium dodecyl sulfate,pulegone in VOHS microcapsule showed a certain degree of slow release.Compared with β-cyclodextrin method,the microencapsulation used in the present work could reduce the amount of excipients and increase the drug loading.It was beneficial to reduce the dose of Chinese medicines containing volatile oils. 相似文献
11.
Survey of antioxidant capacity and phenolic composition of blueberry, blackberry, and strawberry in Nanjing 总被引：1，自引：0，他引：1
Wu-yang Huang Hong-cheng Zhang Wen-xu Liu Chun-yang Li 《Journal of Zhejiang University. Science. B》2012,13(2):94-102
Berries are a good source of natural antioxidants. In the present study, the total antioxidant capacity and phenolic composition
of three berry fruits (blueberry, blackberry, and strawberry) cultivated in Nanjing were investigated. Blueberry, with a Trolox
equivalent antioxidant capacity (TEAC) value of 14.98 mmol Trolox/100 g dry weight (DW), exhibited the strongest total antioxidant
capacity using both the 2,2-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) and the 2,2-diphenyl-1-picrylhydrazyl
(DPPH) methods. Blueberry also had the highest total phenolic content (TPC, 9.44 mg gallic acid/g DW), total flavonoid content
(TFC, 36.08 mg rutin/g DW), and total anthocyanidin content (TAC, 24.38 mg catechin/g DW). A preliminary analysis using high
performance liquid chromatography (HPLC) showed that the blueberry, blackberry, and strawberry samples tested contained a
range of phenolic acids (including gallic acid, protocatechuic acid, p-hydroxybenzoic acid, vanillic acid, caffeic acid, p-coumaric acid, ferulic acid, ellagic acid, and cinnamic acid) and various types of flavonoids (flavone: luteolin; flavonols:
rutin, myricetin, quercetrin, and quercetin; flavanols: gallocatechin, epigallocatechin, catechin, and catechin gallate; anthocyanidins:
malvidin-3-galactoside, malvidin-3-glucoside, and cyanidin). In particular, the blueberries had high levels of proanthocyanidins
and anthocyanidins, which might be responsible for their strong antioxidant activities. These results indicate a potential
market role for berries (especially blueberries) as a functional food ingredient or nutraceutical. 相似文献
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Stephanie Vie 《Technical Communication Quarterly》2017,26(3):344-359
ABSTRACTThe author reports on social media research in technical and professional communication (TPC) training through a national survey of 30 professional and technical communication programs asking about their use of social media in technical communication. This research forms the basis of recommendations for training online TPC faculty to teach with social media. The author offer recommendations throughout for those who train online TPC faculty as well as for the teachers themselves. 相似文献
14.
Jin-hui Yu Jie Sun Fei Bian Gao Chen Yan Zhang Yu-ping Bi Ying-jie Wu 《Journal of Zhejiang University. Science. B》2017,18(9):797-806
Crypthecodinium cohnii (dinoflagellate) and Schizochytrium sp. (thraustochytrid) are the main sources for docosahexaenoic acid (DHA). The present study aimed to evaluate the antioxidant activity of petroleum ether, ethyl acetate, n-butanol, and water fractions of alcohol aqueous extracts of these two microalgae and to provide a theoretical basis for comprehensive utilization. The antioxidant activity was determined by total antioxidant capacity (TAC) determination, 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay, ferrous ion-chelating ability (FICA) assay, and reducing power (RP) assay. The total phenolic content (TPC) and total flavonoid content (TFC) were also measured by the Folin-Ciocalteu and spectrophotometry methods, respectively. The results indicated that the extracts from these two microalgae possessed good antioxidant capacity. Analysis showed that most antioxidant performance indicators (TAC, DPPH, and RP) were positively correlated with the TPC of the extracts, suggesting that the phenolics might be the major components in C. cohnii and Schizochytrium sp., contributing to their antioxidative function. Therefore, the polar fractions of C. cohnii and Schizochytrium sp. could be further examined and considered for application in health products or cosmetics. 相似文献
15.
采用顶空固相微萃取( HS-SPME)技术提取干、鲜杏花的挥发性成分,经气相色谱-质谱测定,比较分析干、鲜杏花的香气成分变化.分析结果表明：鲜杏花中鉴定出2种挥发组分,占总挥发组分相对百分含量的95.09%,苯甲醛占总挥发组分的93.55%;干杏花中鉴定出20种挥发组分,占总挥发组分相对百分含量的92.17%,其中苯甲醛占总挥发组分的25.07%.可见干、鲜杏花挥发油化学成分种类和含量均有明显的差别. 相似文献
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Vacuum pyrolysis was employed to dispose scrap brominated epoxy printed circuit boards (PCBs). Pyrolysis characteristics of waste PCBs under normal pressure and vacuum were investigated in this paper. A detailed study on the analysis of the elemental composition of PCBs and the pyrolysis products was performed. The thermal decomposition kinetics was measured by a thermogravimetric (TG) analyzer. The activation energy of pyrolysis under nitrogen atmosphere and vacuum were 193 kJ/mol to 206 kJ/mol and 145 kJ/mol to 165 kJ/mol, respectively. The composition of materials was analyzed by elemental analyzer. The pyrolysis products were analyzed by GC (gas chromatograph), GC-MS (chromatography and mass spectrometry) and FT-IR (Fourier transform infrared spectroscopy). Vacuum helped to increase the yield of pyrolysis oil. The liquid yield of PCBs pyrolysis at 15 kPa and normal pressure were 31.3? and 23.5?, respectively. The main components in pyrolysis oils were phenol, isopropyl-phenol, and their brominated substitution. 相似文献
18.
Hu-zhe Zheng In-Wook Hwang Shin-Kyo Chung 《Journal of Zhejiang University. Science. B》2009,10(12):912-919
The effects of process variables such as enzyme types, enzyme ratio, reaction temperature, pH, time, and ethanol concentration on the extraction of unripe apple polyphenol were investigated. The results indicated that Viscozyme L had the strongest effect on polyphenols extraction and was selected to study the polyphenol composition. The ratio of enzyme (Viscozyme L) to substrate (2 fungal beta-glucanase units (FBG)) at 0.02, reaction at pH 3.7,50 ℃ for 12 h, and ethanol concentration of 70% were chosen as the most favorable extraction condition. Total phenolic content (TPC), reducing sugar content (RSC), and extraction yield increased by about 3,1.5, and 2 times, respectively, compared with control. The contents of p-coumaric acid, ferulic acid, and caffeic acid increased to 8,4, and 32 times, respectively. The enzyme-aided polyphenol extraction process from unripe apples might be applied to food industry for enhancing bioactive compound production. 相似文献
19.
藏红花挥发性化学成分的气相色谱-质谱分析 总被引：1，自引：0，他引：1
通过分析藏红花挥发性化学成分,为藏红花的开发利用提供科学依据．采用同时蒸馏-萃取法提取藏红花挥发油,用气相色谱法分离,质谱法鉴定结构．结果表明藏红花挥发油的含量为4．30％,鉴定出46种化学成分,其中烯烃、烯烃氧化物及酸类化合物含量较高． 相似文献
20.
This article provides an opportunity to extend the discussion about teacher communities as part of complex school reform models, specifically centered on those communities whose membership is drawn on a semi-voluntary basis. Through a sixteen-month long ethnography, I document the activities of an urban teacher professional community (TPC) at a high school located in a large city in the Northeast, serving a majority of linguistically and culturally diverse students. Guided by Sharp and Greens definition of teacher ideologies, the study focuses on how TPC members negotiated curriculum, teacher learning, and student discipline, carrying ideologies that impacted the outcomes of the communitys work, originally intended to increase teacher collaboration and foster quality teaching.Jorgelina Abbate-Vaughn is an Assistant Professor in the Department of Curriculum and Instruction at the University of Massachusetts-Boston. Her research interests center on the possibilities and challenges that urban schools pose, on school reform approaches, on teacher preparation, and on e.ective educational approaches for low-income, culturally and linguistically diverse (LCLD) students. Address correspondence to Jorgelina Abbate-Vaughn, Graduate School of Education- Department of Curriculum and Instruction, University of Massachusetts- Boston, Wheatley Hall 2nd .floor, Room 99-04- Boston, MA 02125, USA; e-mail: jorgelina. abbate@umb.edu. 相似文献