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21.
Three divalent transiton‐metal complexes of 2,3‐pyridinedicarboxylate (2,3‐pda2), [Mn(2,3‐pda)‐(H2O)3]∞ ( 7 ), [Ni(2,3‐pda)(H2O)3]∞ ( 8 ), and [Cd2(2,3‐pda)2(H2O)]∞ ( 9 ) have been hydrothermally synthesized and structurally characterized. X‐ray diffraction analyses reveal that compounds 7 and 8 are zigzag‐ and linear‐type one‐dimension (1D) coordination polymers, respectively, whereas compound 9 is a three‐dimension (3D) coordination polymer. A simple comparison of the coordination geometries with the available neutral analogues {Mx(2,3‐pda)x(H2O)y}∞ containing one or two divalent transition‐metal atoms and equal ligands in the presence or absence of coordinated water molecules is also presented. 相似文献
22.
借助定量金相、扫描电子显微镜、透射电子显微镜等微观分析手段对钨质量分数为93%的钨合金在15~50GPa冲击压力下微观结构响应性态进行了考察,发现了一些钨合金所特有的现象,即钨颗粒与粘结相交界处出现成分迁移,新相析出;并结合断口分析,探讨了钨合金在冲击作用下发生断裂的微观特征与韧脆转化间的关系及其物理本质。 相似文献
23.
Ai Jun HOU Hui YANG Bei JIANG Qin Shi ZHAO Yan Ze LIU Zhong Wen LIN Han Dong SUN Laboratory of Phytochemistry Kunming Institute of Botany Chinese Academy of Sciences Kunming Department of Phytochemistry Henan College of Traditional Chinese 《中国化学快报》2000,11(9)
In continuation of our research on diterpenoids in the Isodon species, several newcompounds"' were obtained from the leaves oflsodon xerophilus (C. Y. Wu et H. W. Li)H. Hara (Labiatae), a perennial shrub native to Yunnan province. Further fractionation ofthe EtOAc extract led to the isolation of tWo new enl-kauranoids, xerophilusin E (l) andxerophilusin F (2). This paper deals with the structUral elucidation of the newcompounds.Xerophilusin E (l), a minor constitUent, was obtained as p… 相似文献
24.
Most magnetorheological materials, composed of magnetic microparticles in a liquid, require significant amounts of magnetic particles and a large magnetic field to achieve the desired effects. Here, we report on a new type of magnetorheological materials consisting of small amounts of magnetic nanoparticles (0.8 wt %) but exhibiting large rheological change (i.e., a gel-sol transition) upon the application of a small magnetic field. We use self-assembly to create hybrid nanofibers, which consist of supramolecular hydrogelators and magnetic nanoparticles, as the matrices of the hydrogel. Localized in the nanofibers at a distance of 1-2 nm, the magnetic nanoparticles occupy a small volume fraction of the hydrogel, significantly enhancing the magnetic dipole interactions between them, which results in the large magnetoresponse. This strategy generates a hierarchical nanostructure and eliminates several drawbacks of the simple mixture of polymers with nanoparticles, and thus provides a new methodology that uses magnetic force to control the nanostructures and properties of soft materials. 相似文献
25.
Labile rhizosphere soil solution fraction for prediction of bioavailability of heavy metals and rare earth elements to plants 总被引:5,自引:0,他引:5
A labile rhizosphere soil solution fraction has been recommended to predict the bioavailability of heavy metals and rare earth elements to plants. This method used moist rhizosphere soil in combination with a mixture of 0.01 mol L(-1) of low-molecular-weight organic acids (LMWOAs) as extractant. The extracted soil solutions were fractionated into two colloidal fractions of <0.45 microm (F(3)) and <0.2 microm (F(2)), and one truly dissolved fraction including free metal ions and inorganic and organic complexes (fractionr(0.2 microm, LMWOAs) approximately r(0.45 microm, LMWOAs). In the case of rare earth elements the good correlation was obtained for both the wheat roots and shoots. Generally, the correlation coefficients obtained by LMWAOs were better than that obtained by the first step of BCR method. Therefore, LMWAOs and F(lrss) were strongly recommended to predict the bioavailability of metals in soil pools to plants. 相似文献
26.
E. A. Dikusar N. G. Kozlov V. I. Potkin T. D. Zvereva A. P. Yuvchenko M. P. Bei N. V. Kovganko 《Chemistry of Natural Compounds》2006,42(5):539-542
Previously unreported esters 1b–20b were synthesized from natural terpene alcohols, sterols, plant phenols, and camphar oxime (1a–20a) by reaction with o-carborane-C-carboxylic acid chloride.
__________
Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 434–436, September–October, 2006. 相似文献
27.
Two new heteropolynuclear metal complexes [Ni(phen)2]3[Cr(ox)3]2·8H2O(1) and [Ni(bipy)2]2[Cr(ox)3]NO3·4H2O(2)(phen=1,10-phenanthroline, ox=oxalato, bipy=2,2-bipyridine) have been synthesized and characterized by elemental analyses, IR, TG-DTA and diffuse reflectance UV-VIS spectra. The temperature dependence of the magnetic susceptibilities of the complexes have been studied over the range 73.6~300K. The results show that ferromagnetic spin exchange interaction exist between Cr(Ⅲ) and Ni(Ⅱ) in the complex (1). The magnetic property of the complex(2) abides Curie law. 相似文献
28.
Ming Guo Jue Wang Man Xiong Ronghui Wu Xuejuan Yang Jianzhong Zhou Minghui Li Jiajun Li 《大学化学》1986,35(12):237-246
In order to improve university laboratory teaching and practical education under the background of information technology, as well as overcome the difficulty for practical training, develop a virtual simulation experiment platform for rapid pyrolysis of natal materials and high-performance liquid chromatographic (HPLC) detection of its components. The experiment integrates the actual operation process of the plant to produce cleaved products by rapid pyrolysis of biomass with HPLC detection. The virtual experiment is divided into biomass sample pretreatment, rapid biomass pyrolysis, bio-oil extraction, and HPLC determination of complex components, making the biomass cleavage workshop "real" through simulation. This virtual simulation experiment fully integrates the utilization of biomass resources and basic chemistry courses (such as organic chemistry, instrumental analysis, chemical engineering principles, etc.), which are widely involved in agricultural and forestry majors with advantageous characteristics value. 相似文献
29.
Peilin Z Jianzhong Z Shenzhong Y Xikang Z Guoxiong Z 《Analytical and bioanalytical chemistry》1995,353(2):171-173
The electrochemical characterization of boron-doped polycrystalline diamond thin-film (BDF) electrodes was studied using the anodic scan after concentrating lead in 0.1 mol/L KCl - 41 micromol/L Hg(NO(3))(2) and 0.1 mol/L KNO(3) - 0.01 mol/L HNO(3) - 41 micromol/L Hg(NO(3))(2); accumulation voltage was -0.90 V. The results obtained were compared with those given by glassy carbon (GC) electrodes and proved that the BDF electrodes offered high sensitivity, good precision and extreme stability over a 2-month period. These electrodes provided good resolving power for the determination of lead and cadmium and gave satisfactory results in the analysis of a pure water sample. 相似文献
30.
3 D-QSAR Analysis of Agonists of nAChRs: Epibatidine Analogues 总被引:1,自引:0,他引:1
HuaBeiZHANG ChunPingLIU 《中国化学快报》2004,15(11):1380-1382
A 3 D-QSAR about nAChRs agonists epibatidine analogues was performed using theCoMFA and CoMSIA. The correlation coefficients were R2cv = 0.546, R2cv = 0.907 in CoMFA andR2cv = 0.655, R2,~ = 0.962 in CoMSIA of the final model. The prediction using the final models tothe test set was r2 = 0.675 in CoMFA and r2 = 0.462 in CoMSIA. This model will be useful in thedesign of novel compounds with high affinity. 相似文献