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991.
The 1,3-dipolar cycloaddition reaction of meso-tetraaryl porphyrin with 2,6-dichlorobenzonitrile oxide yielded novel isoxazoline-fused chlorins and two stereoisometric bacteriochlorins. The crystal structure of bacteriochlorin was characterized by X-ray diffraction. 相似文献
992.
Matrix-assisted laser desorption/ionization (MALDI) mass spectrometry has the potential to become a valuable tool for the compositional analysis of copolymers. For a copolymer composed of structurally very similar building blocks with minor chain length changes, one would expect the relative peak intensities observed in the MALDI mass spectra to reflect its composition, at least within a narrow mass range. However, we show that variations in experimental conditions in MALDI can have a significant effect on the mass spectral appearance of a copolymer. The effects of concentration, laser power, type of matrices and solvents on mass spectra of an ethylene oxide/propylene oxide copolymer are illustrated. These somewhat surprising results show that great care needs to be exercised when interpreting copolymer spectra for compositional analysis, even for copolymers with structurally similar monomers. This work also points out that further studies are needed to better understand and optimize spectral acquisition conditions for reliable copolymer compositional analysis by MALDI. 相似文献
993.
994.
研究了四元体系CsCl-LaCl3-HCl-H2O(25℃、「HCl」=13%(wt),23%(wt)和CsCl-LaCl3-HAc-H2O(30℃,「HAc」=42%(wt))的平衡态的溶度数据,并给出制了相应的溶度图,共得到了CsCl.LaCl3.4H2O、2CsCl.LaCl3.2H2O和3CsCl.LaCl3.3H2O3种化合物。对得到的新相进行了热分析,X射线粉末衍射及偏光性质的测定,依 相似文献
995.
ZheLi DangLi WeiHuang KechangXie 《天然气化学杂志》2005,14(2):115-118
The Cu-Mo/ZSM-5 catalysts with different Cu/Mo ratios were prepared by wet impregnation method, and their catalytic performance for selective catalytic reduction of NOx was studied. The results showed that Cu-Mo/ZSM-5 is a very effective catalyst for NOx catalytic reduction with ammonia, especially when Cu/Mo molar ratio is about 1.5. It not only exhibited the extremely high catalytic activity, but also showed good stability for 02. The bulk phase structure of Cu-Mo/ZSM-5 catalysts was determined by XRD technique, and the results indicated that there is a maximum dispersion for Cu species when Cu/Mo molar ratio is 1.5, and an interaction between Cu and Mo along with HZSM-5 may be present in Cu-Mo/ZSM-5, which may possibly result in a special structure favorable for the catalytic reduction of NOx over Cu-Mo/ZSM-5 catalyst. 相似文献
996.
997.
ADSORPTION OF 2,4-DICHLOROBENZOXYACETIC ACID ONTO HYPERCROSSLINKED RESIN MODIFIED BY PHENOLIC HYDROXYL GROUP (AM-1) 总被引:2,自引:0,他引:2
INTRODUCTIONAdsorption has been considered to be the best available technology for removing organics from water in the USSafe Drinking Water Act[1]. Due to many drawbacks of activated carbon[2-7], the most widely used adsorbent,hypercrosslinked polymeric adsorbents developed by Tsyurupa and Davankov[8] have been increasingly viewedas an alternative to activated carbon for selective removal of specific organic substances from contaminatedwater[9-12], and series of researches have been do… 相似文献
998.
A single phase solid solution of Ce-Zr-O can be made by using NH4HCO3 solution as precipitating agent. The influence of preparation conditions, such as pH, Zr4+/(CO3
2-+HCO3
-) and Ce3+/Zr4+ ratio on the formation of the solid solution were investigated. The results show that a single phase Ce-Zr-O solid solution
can be formed only under a narrow window of preparation conditions, indicating that some compounds are formed in the precipitating
process. The compound may contain Ce3+, Zr4+, CO3
2-, HCO3-, and OH-. The solid solution so prepared can be described as Ce0.37Zr0.63O2.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
999.
Shuang‐Jun Lin Chang‐Heng Tan Shan‐Hao Jiang Yi‐Ming Li Da‐Yuan Zhu 《Helvetica chimica acta》2006,89(11):2789-2793
Four new iridoids, buergerinins B–E ( 1 – 4 ), along with three known iridoids, were isolated from the roots of Scrophularia buergeriana. Their structures were identified on the basis of spectroscopic analysis. 相似文献
1000.
New spirocyclic heterocycles 8, 16, 19/20, 25, 27 , and 30 derived from pyrimido[4,5‐b][1,4]diazepin]‐8′(9′H)‐one were synthesised by a tandem nitroso‐ene/Diels–Alder reaction of 4‐(alkenoylamino)‐5‐nitrosopyrimides. The crystal structure of 16 was established by X‐ray analysis. It is characterised by four pairs of intermolecular H‐bonds linking every two molecules in the unit cell. Sequential imine reduction and intramolecular condensation of the C(4′)‐(acylamino)‐pyrimido[4,5‐b][1,4]diazepines 27 and 30 led to the [1,4]diazepino[1,2,3‐gh]purines 28 / 29 and 31 , respectively. 相似文献