首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   11篇
  免费   0篇
化学   11篇
  2011年   3篇
  2009年   1篇
  2008年   1篇
  2004年   1篇
  2001年   1篇
  1998年   1篇
  1984年   2篇
  1979年   1篇
排序方式: 共有11条查询结果,搜索用时 15 毫秒
1.
The separation and detection of both print and film developing agents (CD-3 and CD-4) in photographic processing solutions using chip-based capillary electrophoresis is presented. For simultaneous detection of both analytes under identical experimental conditions a buffer pH of 11.9 is used to partially ionise the analytes. Detection is made possible by indirect fluorescence, where the ions of the analytes displace the anionic fluorescing buffer ion to create negative peaks. Under optimal conditions, both analytes can be analyzed within 30 s. The limits of detection for CD-3 and CD-4 are 0.17 mM and 0.39 mM, respectively. The applicability of the method for the analysis of seasoned photographic processing developer solutions is also examined.  相似文献   
2.
The inhibitory activity on pancreatic α-amylase by cyanidin-3-rutinoside was examined in vitro. The IC?? value of cyanidin-3-rutinoside against pancreatic α-amylase was 24.4 ± 0.1 μM. The kinetic analysis revealed that pancreatic α-amylase was inhibited by cyanidin-3-rutinoside in a non-competitive manner. The additive inhibition of a combination of cyanidin-3-rutinoside with acarbose against pancreatic α-amylase was also found. These results provide the first evidence for the effect of cyanidin-3-rutinoside in a retarded absorption of carbohydrates by inhibition of pancreatic α-amylase which may be useful as a potential inhibitor for prevention and treatment of diabetes mellitus.  相似文献   
3.
Cholesterol-lowering activity of the major polyphenols in grape seed   总被引:1,自引:0,他引:1  
The major polyphenols in grape seed have been shown to have beneficial health effects in the prevention of dyslipidemia and cardiovascular diseases. In this present study, we investigated the cholesterol-lowering activity of three major polyphenolic compounds found in grape seed. The results showed that gallic acid, catechin, and epicatechin significantly inhibited pancreatic cholesterol esterase in a concentration-dependent manner. Moreover, they bound to taurocholic acid, taurodeoxycholic acid, and glycodeoxycholic acid at levels ranging from 38.6% to 28.2%. At the concentration of 0.2 mg/mL, gallic acid, catechin, and epicatechin reduced the formation of cholesterol micelles 27.26 ± 2.17%, 11.88 ± 0.75%, and 19.49 ± 3.71%, respectively. These findings clearly demonstrate that three major polyphenolic compounds present in a particular grape seed have cholesterol-lowering activity by inhibiting pancreatic cholesterol esterase, binding of bile acids, and reducing solubility of cholesterol in micelles which may result in delayed cholesterol absorption.  相似文献   
4.
The structures of 8,8′-bis(3-phenylthioureidomethyl)-2,2′-binaphthalene (1), 8,8′-bis(3-butylthioureidomethyl)-2,2′-binaphthalene (2) and their complexes with anionic guests such as carboxylate ions (acetate, oxalate, malonate, succinate, glutarate, adipate, pimelate, suberate, and azelate), inorganic oxygen-containing anions (nitrate, sulfate, bicarbonate, hydrogen phosphate, and dihydrogen phosphate), and halide ions (fluoride, chloride, and bromide) were obtained using the ONIOM approach. The binding abilities of receptors 1 and 2 to anionic species in terms of binding energy, thermodynamic properties, and selectivity coefficient were obtained at the ONIOM(B3LYP/6-31G(d):AM1) and BSSE-corrected B3LYP/6-31G(d)//ONIOM(B3LYP/6-31G(d):AM1) levels of theory. The multipoint hydrogen bonding between receptors (either the receptor 1 or 2) and anionic guests were found. The hydrogen phosphate is the most preferable ion to bind with either the receptor 1 or 2.  相似文献   
5.
This paper describes the methodological optimization and validation of a simple micellar electrokinetic chromatography for the rapid simultaneous separation of 2-methyl-4-isothiazolin-3-one, methylparaben, ethylparaben, propylparaben, and butylparaben. By using a 30 mM phosphate buffer (pH 7.2) containing 30 mM sodium dodecyl sulfate (SDS), an applied voltage of 10 kV and a separation temperature of 40 degrees C, a quantitative determination was achieved, resulting in an analysis time of approximately 4 min. Only dilution and filtration are needed before analysis. The parameters for validation, such as linear ranges, detection limits, accuracy, and precision, are also reported.  相似文献   
6.
An efficient one-pot synthesis of α,β-unsaturated ketones via the decarboxylative elimination of sodium glycidates with lead tetraacetate is described.  相似文献   
7.
The hexane extract from the leaves of Dasymaschalon sootepense Craib (Annonaceae) showed strong cytotoxic activity against the L1210 tumor cell line. Activity-directed fractionation of the extract by column chromatography on silica gel and high-pressure liquid chromatography led to the isolation of the acetogenins 1 – 4 as the main active principles. The structures of the two novel structures named sootepensin A ( 1 ) and sootepensin B ( 2 ) were elucidated by spectroscopic analysis (UV, EI- and ESI-MS, 1D- and 2D-1H- and 13C-NMR). The absolute configurations were established by 2D-NMR experiments utilizing Mosher esters. Two recently described compounds, tonkinin C ( 3 ) and tonkinesin C ( 4 ), were also isolated and are new to the genus Dasymaschalon. All four acetogenins were found to be highly cytotoxic against the L1210 tumor cell line.  相似文献   
8.
Sirichai S  Khanatharana P 《Talanta》2008,76(5):1194-1198
Capillary electrophoresis (CE) with UV detection for the simultaneous and short-time analysis of clenbuterol, salbutamol, procaterol, fenoterol is described and validated. Optimized conditions were found to be a 10 mmoll(-1) borate buffer (pH 10.0), an separation voltage of 19 kV, and a separation temperature of 32 degrees C. Detection was set at 205 nm. Under the optimized conditions, analyses of the four analytes in pharmaceutical and human urine samples were carried out in approximately 1 min. The interference of the sample matrix was not observed. The LOD (limits of detection) defined at S/N of 3:1 was found between 0.5 and 2.0 mgl(-1) for the analytes. The linearity of the detector response was within the range from 2.0 to 30 mgl(-1) with correlation coefficient >0.996.  相似文献   
9.
The taxodeaceous plant A. Selaginoides contains six known homoerythrina-type alkaloids and selaginoidine, which has a furan ring replacing the benzene ring of the latter type. Selaginoidine and five of the six above-mentioned alkaloids also occur in A. laxifolia.  相似文献   
10.
Eleven homoerythrina-type alkaloids (tilda1-tilda9, tilda11, tilda12) have been isolated from A. cupressoides (Taxodiaceae), of which six (tilda6-tilda9, tilda11,tilda12) had not previously been reported.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号