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221.
Hongyu Liu Xinhui Guo Juncheng Chen Aobo Song Gu Jin Qizhi Yao Jiao Li Lingling Li 《大学化学》1986,35(12):221-226
This paper introduces an experiment about waste liquid recovery and effect evaluation in laboratory. Through this experiment, the basic operations of crystal preparation, chemical analysis and instrumental analysis are further consolidated. At the same time, it allows students to experience a series of possible problems of condition selection and control in the process of waste liquid treatment. We hope to improve the students' ability to analyze and solve problems, enhance their interest in learning, and strengthen their humanistic education. 相似文献
222.
In vivo near-infrared Raman spectroscopy: demonstration of feasibility during clinical gastrointestinal endoscopy 总被引:7,自引:0,他引:7
Raman spectroscopy (RS) has potential for disease classification within the gastrointestinal tract (GI). A near-infrared (NIR) fiber-optic RS system has been developed previously. This study reports the first in vivo Raman spectra of human gastrointestinal tissues measured during routine clinical endoscopy. This was achieved by using this system with a fiber-optic probe that was passed through the endoscope instrument channel and placed in contact with the tissue surface. Spectra could be obtained with good signal-to-noise ratio in 5 s. The effects on the spectra of varying the pressure of the probe tip on the tissue and of the probe-tissue angle were determined and shown to be insignificant. The limited set of spectra from normal and diseased tissues revealed only subtle differences. Therefore, powerful spectral-sorting algorithms, successfully implemented in prior ex vivo studies, are required to realize the full diagnostic potential of RS for tissue classification in the GI. 相似文献
223.
224.
The bridged tri-imidazoliums 3.3X^--5.3X^-(X^-=PF6^-,Br^-,I^-)and bis-imidazoliums 6.2PF6^- were synthesized by N-quaternization of imidazole derivative 1 in acetonitrile under reflux.UV spectroscopic titration experiments showed that the halide salts and hexafluorophosphate salts of these imidazoliums exhibited good recognition toward anions in water and in acetonitrile,respectively. 相似文献
225.
Ren Yanliang Cheng Lin Wan Jian Li Yongjian Liu Junjun Yang Guangfu Zhang Lihua Yang Song 《中国科学B辑(英文版)》2006,49(1):88-96
The electronic singlet vertical excited states of photosynthetic reaction center (PSRC) in Rhodopseudomonas (Rps.) viridis were investigated by ZINDO and INDO/S methods. The effects of the interactions of pigment-pigment and pigment-protein on
the electronic excitations were examined. The calculation results showed that the interactions of pigment-pigment and pigment-protein
play an important role in reasonably assigning the experimental absorption and circular dichroism (CD) spectra of PSRC in
Rps. virids. By comparing the theoretically computed excited states with the experimental absorption and CD spectra, satisfactory assignments
of the experimental spectroscopic peaks were achieved. 相似文献
226.
The stereo- and regioselective synthetic route to pimaraditerpenes, employing an angular hydroxymethyl directed intramolecular Diels-Alder reaction of the decaline intermediate, has been developed. This synthetic approach allows prompt access to both natural pimaraditerpenes and the unnatural regioisomers, which would be potentially new anti-inflammatory pimaraditerpenes. 相似文献
227.
Yanning Song 《Journal of solid state chemistry》2003,175(1):63-71
A new two-dimensional (2d) iron phosphate, (C2N2H10)Fe2O(PO4)2, has been synthesized under hydrothermal conditions in the system of FeCl3-H3PO4-C2N2H8-H2O. The crystal data is: space group P21/c, a=10.670(1) Å, b=10.897(1) Å, c=9.918(1) Å, β=105.632(1)°, Z=4. The layered structure consists of double sheet layers, of composition Fe2O(PO4)2, built from FeO5 trigonal bipyramids and PO4 tetrahedra. The amine holds the layers together via H-bonding. The study of the magnetic properties reveals two magnetic transitions at 160 and 30 K with spin-glass-like behavior below 160 K. By varying the hydrothermal conditions, three other iron phosphates were synthesized: the one-dimensional (1d) (C2N2H10)Fe(HPO4)2(OH)·H2O, the 2d (C2N2H10)Fe2(PO4)2(OH)2, and the three-dimensional (3d) (C2N2H10)2Fe4O(PO4)4·H2O. The 1d compound can be used as the starting reagent in the synthesis of both the 2d compound and the 3d lipscombite Fe3(PO4)2(OH)2 due to the similar building blocks in their structures. In the 3d phosphate (C2N2H10)2Fe4O(PO4)4·H2O, manganese can substitute for half of the iron atoms. Magnetic study shows ordering transitions at about 30 K, however, manganese substitution depresses the magnetic ordering temperature. 相似文献
228.
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230.
A two-dimensional layered manganese(Ⅱ) pyrophosphate, [NH4]2[Mn3(P2O7)2(H2O)2] (1), has been synthesized hydrothermally. Its structure is determined by single-crystal X-ray diffraction analysis. Its structure is built up by MnO6 octahedra and P2O7 units, with ammonium NH4+ cations residing in the interlayer regions. The manganese pyrophosphate layer consists of infinite chains of cis and trans edge sharing MnO6 octahedra linked by P2O7 units. Magnetic susceptibility measurements show that this compound exhibits ferrimagnetic-like ordering below 3.2 K. Further study shows that there are two possible superexchange pathways via the oxygen anions in Mn2+ ions. Owing to the different bridging modes of O2-, the competition between ferromagnetic interactions and antiferromagnetic interactions in Mn2+ ions results in the ferrimagnetic behavior of 1. 相似文献