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71.
GC/MS法分析奶油中的脂肪酸 总被引:1,自引:0,他引:1
利用气相色谱/质谱/计算机联用技术分析人造奶油、天然奶油和新西兰奶油中的脂肪酸,从中鉴定出7种酸:棕榈酸、棕榈油酸、硬脂酸、油酸、亚油酸、亚麻油酸及花生酸。人造奶油含亚油酸比天然奶油含的高。 相似文献
72.
Gang XU Cheng Cai AN Jun FENG Yun Xiang CI Jin Hua TIAN Zhang Liang CHENI 《中国化学快报》2000,11(7):597-600
IthasbeenreportedthatTrichosanthi11(TCS),isolatedfromrkiI-ilolt)ii,hasanti-tumorI-4andanti-vira1activities5-'.Someanti-tun1orremedies,whicharedesignedfromTCS,arebeingtestedanddeveloped'-.'.StudyingthebioIogicalphenomenonbyelectrochemicalmethodsisanewhotresearchspotemerginginrecentyears".Manyresultsshowedthatnotonlytheenzymesystemsuchassuccinatedehydrogenasedisplayedthediode-likebehaviorduringtheelectrontransferprocess",butalsothehigh1yorganizedorganeIle,forexample,mitochondria,andevenintac… 相似文献
73.
74.
A novel photothermal phase-shift spectroscopy configuration based on the retro-reflected beam interference has been developed and its operational principle is described. The weak absorption measurement ability of this technique is experimentally proven with a water/ethanol solution of standard Pyronine G dye and the limit of detection is found to be 1.8 x 10(-6) absorbance. Potential applications of the technique are discussed. 相似文献
75.
2-Substituted homophthalimides 2a-c were reduced regioselectively with sodium borobydride to carbinol-lactam intermediates 3a-c , which were dehydrated, followed by hydrogenation, to give 1-oxo-tetrabydroisoquinolines or 3,4-dihydroisoquinolin-1(2H)ones 5a-c . The isomeric 3-oxo-tetrahydro-isoquinolines or 1,4-dihydroisoquinolin-3(2H)-ones 8a-i were obtained in satisfactory yields via heating 3-isochromanone ( 6 ) with the corresponding amines 7a-i in the presence of aluminum chloride. 相似文献
76.
A newly developed unbiased structural optimization method, named dynamic lattice searching (DLS), is proposed as an approach for conformational analysis of atomic/molecular clusters and used in understanding the energy landscape of large clusters. The structures of clusters are described in terms of the number of basic tetrahedron (BT) units they contain. We found that the hit numbers of different structural motifs in DLS runs is proportional to the number of BTs. A parameter T(max) is defined to limit the maximal number of atoms moved in a structural transition. Results show that T(max) is a key parameter for modulating the efficiency of the DLS method and has a great influence on the hit number of different motifs in DLS runs. Finally, the effect of potential range on the conformational distribution of the (Morse)(98) cluster is also discussed with different potential-range parameters. 相似文献
77.
Tian S.-J. Xi G.-X. Cheng Q.-T. Lou X.-D. Li J.-H. 《Journal of Thermal Analysis and Calorimetry》1998,53(3):825-833
The inclusion complex of benzaldehyde (BA) with β-cyclodextrin (β-CD) was prepared and was studied by thermal analysis and
X-ray diffractometry. The composition of the complex was identified by TG and elemental analysis as β-CD·BA·9H2O. TG and DSC studies showed that the thermal dissociation of β-CD·BA·9H2O took place in three stages: dehydration in the range 70-120°C; dissociation of β-CD·BA in the range 235-270°C; and decomposition
of β-CD above 280°C. The kinetics of dissociation of β-CD·BA in flowing dry nitrogen was studied by means of TG both at constant
temperature and at linearly increasing temperature. The results showed that the dissociation of β-CD·BA was dominated by a
one-dimensional random nucleation and subsequent growth process (A2). The activation energy E was 124. 8 kJ mol-1, and the pre-exponential factor A 5.04·1011 min-1.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
78.
A beta-iron oxyhydroxide (FeOOH) was synthesized via a hydrolyzing route and investigated as a lithium intercalation host.
It delivers a capacity of about 170 mAh/g and exhibits good cycling performance when charged/discharged in the voltage range
from 1.6 V to 3.3 V. For the first time we have confirmed that FeOOH is suitable for using it as a negative electrode for
hybrid electrochemical supercapacitor assembled with an activated carbon positive electrode in 1.0 M LiPF6 ethylene carbonate/dimethyl carbonate (EC/DMC, 1:2 in volume) solution. The cell reveals a slightly sloping voltage profile
from 0 V to 2.8 V and gives an estimated specific energy of 45 Wh/kg based on the total weight of two electrode materials,
approximately two times of carbon/carbon electrochemical double layer capacitors. The hybrid supercapacitor shows a good cycling
performance, it remains approximately 96% of initial capacity after 800 cycles at a charge/discharge rate of 4 C. The capacitor
also shows a desirable rate capability, even at 10 C discharge rate, it holds 80% of capacity compared with that at 1 C discharge
rate. 相似文献
79.
Synthesis of phthalide derivatives using nickel-catalyzed cyclization of o-haloesters with aldehydes
Rayabarapu DK Chang HT Cheng CH 《Chemistry (Weinheim an der Bergstrasse, Germany)》2004,10(12):2991-2996
The reaction of o-bromobenzoate (1 b) with benzaldehyde (2 a) in the presence of [NiBr(2)(dppe)] (dppe=1,2-bis(diphenylphosphino)ethane) and zinc powder in THF (24 hours, reflux temperature), afforded 3-phenyl-3H-isobenzofuran-1-one (3 a) in an 86 % yield. Similarly, o-iodobenzoate reacts with 2 a to give 3 a, but in a lower yield (50 %). A series of substituted aromatic and aliphatic aldehydes (2 b, 4-MeC(6)H(4)CHO; 2 c, 4-MeOC(6)H(4)CHO; 2 d, 3-MeOC(6)H(4)CHO; 2 e, 2-MeOC(6)H(4)CHO; 2 f, 4-CNC(6)H(4)CHO; 2 g, 4-(Me)(3)CC(6)H(4)CHO; 2 h, 4-C(6)H(5)C(6)H(4)CHO; 2 i, 4-ClC(6)H(4)CHO; 2 j, 4-CF(3)C(6)H(4)CHO; 2 k, CH(3)(CH(2))(5)CHO; 2 l, CH(3)(CH(2))(2)CHO) also underwent cyclization with o-bromobenzoate (1 b) producing the corresponding phthalide derivatives in moderate to excellent yields and with high chemoselectivity. Like 1 b, methyl 2-bromo-4,5-dimethoxybenzoate (1 c) reacts with tolualdehyde (2 b) to give the corresponding substituted phthalide 3 m in a 71 % yield. The methodology can be further applied to the synthesis of six-membered lactones. The reaction of methyl 2-(2-bromophenyl)acetate (1 d) with benzaldehyde under similar reaction conditions afforded six-membered lactone 3 o in a 68 % yield. A possible catalytic mechanism for this cyclization is also proposed. 相似文献
80.
The G3(MP2) method has been employed to study the 1,4-addition reactions between singlet oxygen and five acenes, including benzene, naphthalene, anthrecene, tetracene, and pentacene. In all, nine pathways between O(2) and the five acenes have been investigated. Our calculated results indicate that all nine pathways are concerted and exothermic and that the most reactive sites on the acenes are the center ring's meso-carbons. In addition, reactivity increases along the series benzene < naphthalene < anthrecene < tetracene < pentacene. This trend is identical to that of aromaticity for the five acenes. A correlation between reactivity and aromaticity is briefly rationalized with natural bond orbital (NBO) analysis and frontier molecular orbital (FMO) analysis. Furthermore, some experimental kinetics data from the literature supporting the calculated results are cited. 相似文献