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121.
Xin Sheng Li Yan Xin Chen Yao Jun Zhang Chun Xin Ji Qin Xin 《Reaction Kinetics and Catalysis Letters》1996,58(2):391-396
Hydrogen adsorption-desorption over Mo2N has been studied using a temperature-programmed technique. It is revealed that hydrogen on Mo2N exhibits very high mobility leading to migration of the surface hydrogen into the sublayer and bulk of the sample or the reverse. The surface hydrogen species are preferentially formed when adsorption is carried out below 573 K. On increasing the adsorption temperature to above 573 K, the quantity of hydrogen species located in the sublayer or/and bulk of the Mo2N sample increases significantly. 相似文献
122.
A polarographic investigation of the copper-3-hydroxy-1-p-sulphonatophenyl-3-phenyltriazene (HSPT) complex in 0.05 M sodium tetraborate medium is described and a simple and sensitive single-sweep polarographic method for the determination of trace amounts of copper in biological samples is proposed. The complex was shown to be Cu(HSPT)2 with log beta' = 11.38. The polarographic wave is caused by the reduction of copper(II) in the adsorbed complex to copper amalgam on the surface of a mercury electrode. The current peak is directly proportional to the concentration of copper in the range 8.0 x 10(-9)-4.0 x 10(-6) M and the detection limit is 5.0 x 10(-9) M. 相似文献
123.
124.
采用二硫化碳重结晶富勒烯混合物或二硫化碳二次抽提烟灰以提取高富勒烯(higherfulerenes,Cn,n>70)。产物经高效液相色谱分析,高富勒烯的含量从1%分别提高到4%和6%;经激光飞行时间质谱证明,产物中除含主要成分C60和C70以外,还含有C76、C78、C82、C84以及更高碳原子的富勒烯。 相似文献
125.
Four new compounds having nine cluster electrons and cores of the types Mo3OCl3, Mo3OBr3, and W3OCl3 are reported. Compound (1) prepared by reduction of [Bu4N][Mo3OCl6(OAc)3] in THF with metallic zinc, was shown by X-ray crystallography to be Mo3OCl4(OAc)3 (THF)2 (1). It forms crystals in space groupP21 with unit cell dimensionsa=9.472(2) Å,b=13.546(4) Å,c=9.652(2) Å, =101.70(2)°,V=1201(1) Å3,Z=2. The [Mo3(3-O)(-Cl)3]4+ core is surrounded by three -O2CCH3 anions, one Cl–, and two THF and has Mo-Mo distances of 2.620(1) Å, 2.613(1) Å, and 2.530(1) Å, with the shortest bond between the two Mo atoms to which the THF molecules are coordinated. Compounds [Bu4N]2 [Mo3OBr6(O2CCH3)3] · Me2CO, (2) and [Mo3OBr3(O2CCH3)3(PMe3)3]3 · BF4, (3) are the first two nine-electron Mo3 species with a [Mo3(3-O) Br3]4+ core. Both were obtained by zinc reduction of [Mo3OBr6(O2CCH3)3]– in the presence of (NBu4) Br (2) or PMe3 and NaBF4 (3), and each was characterized crystallographically. Compound (2) crystallized in space group Cc with unit cell dimensionsa=25.037(5) Å,b=12.827(2) Å,c=21.484(4) Å, =122.96(1)0,V=5790(3) Å3,Z=4. While the anion has no crystallographically required symmetry, its virtual symmetry is C3v
. The Mo-Mo distances are 2.619(2) Å, 2.610(3) Å, 2.644(2) Å, with a mean value of 2.624[14] Å. Compound (3) crystallized in space groupP21/c with unit cell dimensionsa=10.846(2) Å,b=25.033(5) Å,c=12.641(5) Å, =94.74(2)0,V=3420(2) Å3,Z=4. The cation occupies a general position but has virtual C3v
symmetry, with Mo-Mo distances of 2.601(2) Å, 2.610(2) Å, 2.627(2) Å, with a mean value of 2.613[14] Å. Thus the anionic and cationic Mo3 clusters in (2) and (3), respectively, have average Mo-Mo distances that are equal within experimental error. Compound (4), [NEt4]2 [W3OCl6(O2CCH3)3] is the first 9-electron compound of this type containing tungsten. It was prepared by reduction of [Et4N][W3OCl6(OAc)3] in benzene with Na/Hg. It crystallized in space groupP212121 with unit cell dimensionsa=11.076(2) Å,b=14.345(2) Å,c=21.026(3) Å,V=3574(1) Å3,Z=4. The anion resides on a general position but has virtual C3v
symmetry, with W-W distances of 2.577(1) Å, 2.612(1) Å, 2.584(1) Å and a mean value of 2.591[15] Å. 相似文献
126.
Zhang JJ Sheng TL Hu SM Xia SQ Leibeling G Meyer F Fu ZY Chen L Fu RB Wu XT 《Chemistry (Weinheim an der Bergstrasse, Germany)》2004,10(16):3963-3969
The first successful attempt to construct 3D supramolecular frameworks with high-nuclear 3d-4f heterometallic clusters as a node is reported. The self-assembly of Ln3+, Cu2+ and amino acid in solution leads to the formation of two polymers, 35-nuclear complex [Sm6Cu29] 1 with a primitive cubic net-like structure and 36-nuclear complex [Nd6Cu30] 2 with a face-centred cubic network type structure. Glycine and L-proline, respectively, were used as ligands. It should be noted that 2 has a chiral framework. X-ray structure analyses show that 1 crystallizes in the triclinic P1 space group (a=19.6451(8), b=20.4682(8), c=20.7046(8) A, alpha=89.453(1), beta=66.290(1), gamma=68.572(1) degrees, V=7003.0(5) A3 and Z=1) and 2 belongs to the cubic P2(1)3 space group (a=b=c=32.4341(3) A, V=34 119.7(5) A3 and Z=4). Both complexes utilize Ln6Cu24 octahedral clusters as nodes and trans-Cu(amino acid)2 groups as bridges. Electrical conductivity measurements reveal that both polymers behave as semiconductors. 相似文献
127.
Zhang Z Blom DA Gai Z Thompson JR Shen J Dai S 《Journal of the American Chemical Society》2003,125(25):7528-7529
One-dimensional (1D) magnetic nanomaterials have attracted much attention recently because of their applications in magnetic recording and spintronics. Nevertheless, it remains a challenge to prepare free-standing magnetic nanowires in high yield. This Communication reports the successful high-yield synthesis of an interesting 1D ferromagnetic CoPt alloy by direct decomposition of platinum acetylacetonate and cobalt carbonyl compound in ethylenediamine solvent through a solvothermal reaction. The CoPt alloy nanowires obtained have a tunable diameter of 10-50 nm and a length along the longitudinal axis of up to several microns, depending on crystallization temperature and reaction time. A unique formation mechanism involving coarsening and ripening under solvothermal conditions was discovered. This research opens new opportunities in synthesizing nanomaterials through low-temperature solvothermal processes. 相似文献
128.
本文是笔者在长期教学实践的基础上,对于化学专业生物化学课程教学内容和教学方法,研究的经济总结。其相关成果曾获陕西师范大学优秀教材一等奖及陕西省教学成果二等奖。 相似文献
129.
Tseng CM Dyakov YA Huang CL Mebel AM Lin SH Lee YT Ni CK 《Journal of the American Chemical Society》2004,126(28):8760-8768
Photoisomerization and photodissociation of aniline and 4-methylpyridine at 193 nm were studied separately using multimass ion imaging techniques. Photofragment translational energy distributions and dissociation rates were measured. Our results demonstrate that more than 23% of the ground electronic state aniline and 10% of 4-methylpyridine produced from the excitation by 193 nm photons after internal conversion isomerize to seven-membered ring isomers, followed by the H atom migration in the seven-membered ring, and then rearomatize to both methylpyridine and aniline prior to dissociation. The significance of this isomerization is that the carbon, nitrogen, and hydrogen atoms belonging to the alkyl or amino groups are involved in the exchange with those atoms in the aromatic ring during the isomerization. 相似文献
130.
Two New C—21 Steroidal Glycosides from Cynanchum aurichulatum 总被引:2,自引:0,他引:2
Two new C-21 steroidal glycosides, cynanauriculoside I and cynanauriculoside Ⅱ, were isolated from the roots of Cynanchum aurichulatum. Their structures were established using spectroscopic methods including one and two-dimensional NMR. 相似文献