共查询到20条相似文献,搜索用时 109 毫秒
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哈士蟆油中脂肪酸的GC、GC-MS分析 总被引:5,自引:0,他引:5
用气相色谱(GC)与气相色谱-质谱(GC-MS)联用技术对哈士蟆油中的脂肪酸组成进行了定性与定量分析,共鉴定出10种脂肪酸并用气相色谱法作了定量,对所得的结果进行了讨论。 相似文献
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采用半微量相平衡方法研究了Gd(ClO_4)_3·3H_2O-18C6-CH_3CN三元体系在25℃时的溶解度,测定了饱和溶液的折光率。结果表明,该体系在25℃时形成两种化学计量的配合物,其组成分别为:Gd(ClO_4)_3·18C6·3H_2O·2CH_3CN和Gd(ClO_4)_3·2(18C6)·3H_2O·2CH_3CN,制备了固态配合物,用化学分析及元素分析、IR、DTG、TG及DSC等研究了配合物的组成与性质。 相似文献
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采用国产色谱仪与进口红外光谱仪及接口组成的气相色谱-傅里叶变换红外光谱(GC/FTIR)分析仪,使用大口径毛细管柱,分析了乙苯与苯乙烯固相催化反应液的复杂芳香烃异构体组成,讨论了GC/FTIR分析中随机噪声和基线漂移的去除方法。采用等高线图(CTD)分析技术得到了混合液中各组分的纯气相红外光谱图,最后鉴定了14个气相色谱峰中的9个,占整个色谱峰面积99%以上。 相似文献
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芳香烃异构体的毛细管柱气相色谱—傅里叶变换红外光谱联用技术分析 总被引:1,自引:0,他引:1
采用国产色谱仪与进口红外光谱仪及接口组成的气相色谱-傅里叶变换红外光谱(GC/FTIR)分析仪,使用大口径毛细管柱,分析了乙苯与苯乙烯固相催化反应液的复杂芳香烃异构体组成,讨论了GC/FTIR分析中随机噪声和基线漂的去除方法。采用等高线图9CTD)分析技术得混合液中各组分的纯气相红外光谱图,最后了14个气相色谱峰中的9个,占整个色谱峰面积995以上。 相似文献
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测定了Ln(ClO_4)_3-DAPTU-H_2O(Ln=La,Sm,Yb)三元体系在30℃时的溶解度及饱和溶液的折光率,绘制了相应的溶度图和折光率-组成图,各体系的溶度曲线和折光率曲线均由三支组成,分别与DAPTU、Ln(DAPTU)_2(ClO_4)_3·8H_2O(Ln=La,Sm,Yb)和Ln(ClO_4)_3·nH_2O(Ln=La,n=8;Sm,n=9;Yb,n=8)相对应。从溶度图上发现了3个未见文献报道的固液异组成溶解的化合物,通过化学分析及元素分析、TG-DTG、IR对其进行了表征。 相似文献
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Levuglandins (LGs) and isolevuglandins (isoLGs), formed by rearrangement of endoperoxide intermediates generated through the cyclooxygenase and free radical induced oxidation of polyunsaturated fatty acids (PUFAs), are extraordinarily reactive, forming covalent adducts incorporating protein lysyl ε-amino groups. Because they accumulate, these adducts provide a dosimeter of oxidative injury. This review provides an updated and comprehensive overview of the generation of LG/isoLG in vitro and in vivo and the detection methods for the adducts of LG/isoLG and biological molecules in vivo. 相似文献
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Héloïse Thérien‐Aubin Ariella Lukach Natalie Pitch Prof. Eugenia Kumacheva 《Angewandte Chemie (International ed. in English)》2015,54(19):5618-5622
The entropically driven coassembly of nanorods (cellulose nanocrystals, CNCs) and nanospheres (dye‐labeled spherical latex nanoparticles, NPs) was studied in aqueous suspensions and in solid films. In mixed CNC‐latex suspensions, phase separation into an isotropic latex‐NP‐rich and a chiral nematic CNC‐rich phase took place; the latter contained a significant amount of latex NPs. Drying the mixed suspension resulted in CNC‐latex films with planar disordered layers of latex NPs, which alternated with chiral nematic CNC‐rich regions. In addition, fluorescent latex NPs were embedded in the chiral nematic domains. The stratified morphology of the films, together with a random distribution of latex NPs in the anisotropic phase, led to the films having close‐to‐uniform fluorescence, birefringence, and circular dichroism properties. 相似文献
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Frank-Michael Matysik 《Mikrochimica acta》2008,160(1-2):1-14
Amperometric and conductometric detection are currently the two major electrochemical detection modes in capillary and chip
electrophoresis. The ease of miniaturization and integration of electrochemical detection elements offers a high potential
for the development of portable analytical devices based on electromigrative separations. The challenges and basic concepts
of both detection principles in the context of capillary/chip electrophoresis are shortly introduced and milestones of the
methodical developments are summarized from a historical perspective. Recent advances and applications are discussed with
more detail. Particular attention is paid to new trends in this area of research such as measurements in short capillaries
and the enormous progress and increased popularity of contactless conductivity detection.
Correspondence: Frank-Michael Matysik, Institute of Analytical Chemistry, University of Leipzig, Linnéstr. 3, D-04103 Leipzig,
Germany 相似文献
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Reid GD Whittaker DJ Day MA Turton DA Kayser V Kelly JM Beddard GS 《Journal of the American Chemical Society》2002,124(19):5518-5527
Quenching of redox active, intercalating dyes by guanine bases in DNA can occur on a femtosecond time scale both in DNA and in nucleotide complexes. Notwithstanding the ultrafast rate coefficients, we find that a classical, nonadiabatic Marcus model for electron transfer explains the experimental observations, which allows us to estimate the electronic coupling (330 cm(-1)) and reorganization (8070 cm(-1)) energies involved for thionine-[poly(dG-dC)](2) complexes. Making the simplifying assumption that other charged, pi-stacked DNA intercalators also have approximately these same values, the electron-transfer rate coefficients as a function of the driving force, DeltaG, are derived for similar molecules. The rate of electron transfer is found to be independent of the speed of molecular reorientation. Electron transfer to the thionine singlet excited state from DNA obtained from calf thymus, salmon testes, and the bacterium, micrococcus luteus (lysodeikticus) containing different fractions of G-C pairs, has also been studied. Using a Monte Carlo model for electron transfer in DNA and allowing for reaction of the dye with the nearest 10 bases in the chain, the distance dependence scaling parameter, beta, is found to be 0.8 +/- 0.1 A(-1). The model also predicts the redox potential for guanine dimers, and we find this to be close to the value for isolated guanine bases. Additionally, we find that the pyrimidine bases are barriers to efficient electron transfer within the superexchange limit, and we also infer from this model that the electrons do not cross between strands on the picosecond time scale; that is, the electronic coupling occurs predominantly through the pi-stack and is not increased substantially by the presence of hydrogen bonding within the duplex. We conclude that long-range electron transfer in DNA is not exceptionally fast as would be expected if DNA behaved as a "molecular wire" but nor is it as slow as is seen in proteins, which do not benefit from pi-stacking. 相似文献
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E. Wicke 《Angewandte Chemie (International ed. in English)》1966,5(1):106-122
The study of the structure of water and of aqueous solutions has recently received new impetus from the efforts at commercial desalineation of sea water and from developments in molecular biology. The current view that, apart from single molecules, water contains only one type of structural element, namely “flickering” network structures with tetrahedrally hydrogen-bonded water molecules (two-states model) is proving inadequate in the interpretation of new experimental data and in the calculation of thermodynamic functions. After a critical discussion of the basis of this model and of the concept of hydrogen bonds, a second kind of structural element, i.e. a third state, is suggested: small aggregates of molecules containing mainly non-tetrahedral hydrogen bonds as well as some tetrahedral ones, and packed more densely than allowed by the lattice-like structure. These aggregates – dimers to hexamers – can be regarded as the primary products of disruption of the network structures, and displace the latter as structural components in water with increasing temperature or concentration of solutes. This “combined” model allows a consistent interpretation of the properties of water and of the various effects of dissolved substances. 相似文献
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Thaddeus P McCarthy MC 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2001,57(4):757-774
Seventy-seven reactive organic molecules of astrophysical interest have been identified in a supersonic molecular beam, 73 in the radio band by Fourier-transform microwave spectroscopy, four in the optical by laser cavity ringdown spectroscopy. Most are linear carbon chains, but six consist of carbon chains attached to the compact, highly polar C3 ring, and two are rhomboidal cyclic configurations of SiC3. The laboratory astrophysics of the radio molecules is complete for the time being, in the sense that essentially all the rotational transitions of current interest to radio astronomy (including hyperfine structure when present) can now be calculated to a small fraction of 1 km s(-1) in equivalent radial velocity; six of the radio molecules have already been detected in space on the basis of the present data. The FTM spectrometer employed in this work is far from fundamental limits of sensitivity, so many more molecules can probably be found by refinements of present techniques. The density of reactive molecules in our supersonic beam is generally high by the standards of laser spectroscopy, and many of the radio molecules probably have detectable optical transitions which we are attempting to find, largely motivated by the long-standing problem of the diffuse interstellar bands. Our most interesting result to date is the detection of a fairly strong molecular band at 443 nm in a benzene discharge, in exact coincidence with the strongest and best known interstellar band. Isotopic shifts measured with partially and totally deuterated benzene suggest that the carrier of the laboratory band is a hydrocarbon molecule with the elemental formula CnH5, with n most likely in the range 3-6. 相似文献