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991.
采用火焰原子吸收光谱法测定了儿童常用蜡笔中可溶性铅、镉的含量。铅在0.05~10.00μg·mL~(-1)之间,镉在0.02~4.00μg·mL~(-1)之间具有良好的线性关系。方法的RSD≤4.13%。回收率在93.7%~104.5%之间,测定快速简便,结果准确。可用于蜡笔中可溶性铅、镉含量的监测。 相似文献
992.
A new highly sensitive spectrophotometric method for determination traces of cadmium using Cd-(II)-KI-Crystal Violet system in the presence of Triton X-100-poly(vinyl) alcohol (PVA) mixture has been developed. The apparent molar absorptivity of the system is 1.77 × 105 1-mol–1 cm–1 and its Sandell's sensitivity is 6.35 × 10–4 g·Cd·cm2–. Beer's law is obeyed up to 0.32 g·Cd(II)·ml–1. The method has been applied to determine Cd(II) in waste water, rice and pork meat samples with satisfactory results. 相似文献
993.
994.
Anthony Fratiello Vicki Kubo-Anderson Deborah J. Lee Tai Mao Kwok Ng Scott Nickolaisen Richard D. Perrigan Victor San Lucas Wayne Tikkanen Annie Wong Kenneth Wong 《Journal of solution chemistry》1998,27(4):331-359
A study of zinc(II) and cadmium(II) complexes with isothiocyanate ion has been completed, using a low-temperature, multinuclear magnetic resonance technique that permits the observation of separate resonance signals for bound and free ligand, and Cd(II) metal ion. The Zn2+–NCS– complexes were studied by 1H, 13C, and 15N NMR spectroscopy. In the 1H spectra, the intensity of the coordinated water signal, corresponding to a Zn(II) hydration number of six in the absence of NCS–, decreases dramatically as this anion is added, indicating the complexing process involves more than a simple 1:1 ligand replacement. The 13C and 15N NMR spectra reveal signals for four species, most reasonably assigned to a series of tetrahedrally coordinated Zn2+–NCS– complexes. In the Cd2+–NCS– solution spectra, the 13C and 15N signals for four complexes also are observed and they are three line patterns, corresponding to a doublet from 113Cd J-coupling, and a dominant central peak, resulting from bonding to magnetically inactive Cd isotopes. The 113Cd spectra, showing signals for four complexes, correlate well in all respects with the 13C and 15N results, including coupling in specific cases. The spectral results for both metal ions reflect binding at the nitrogen atom of NCS–, with the complexes changing from an octahedral to a tetrahedral configuration when doing so. Confirming evidence for these conclusions also was provided by several infrared measurements of these metal–ion systems. 相似文献
995.
Photoreduction of Methyl Orange dye (MOr) by sodium sulfide was studied under steady-state photolysis ( = 365 nm). The reaction was sensitized by the CdS colloid with the characteristic 5-nm particle size. The quantum yield of the reaction is independent of the light intensity when the latter is less than 5 mW cm–2. The form of the dependence of the initial quantum yield of the reaction on [MOr] coincides qualitatively with the adsorption isotherm of the dye on the CdS surface. The reaction kinetics under steady-state irradiation were analyzed. The kinetics in solution as a whole are shown to be adequate to those on a single colloidal particle. On the basis of the experimental data, two types of surfaces of the colloidal particles are suggested (open and covered with macromolecules of a colloid stabilizer), which significantly differ in the rate at which they establish an adsorption-desorption equilibrium with the solution.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 244–254, February, 1995.This work was financially supported by the Russian Foundation for Basic Research (Project No. 93-03-4816). 相似文献
996.
997.
We investigated the relationship between the blue-light photoreceptor cryptochrome (CRY) and melatonin biosynthesis by generating RNA interference (RNAi) transgenic rice plants that suppress the cryptochrome 1b gene (CRY1b). The resulting CRY1b RNAi rice lines expressed less CRY1b mRNA, but not CRY1a or CRY2 mRNA, suggesting that the suppression is specific to CRY1b. The growth of CRY1b RNAi rice seedlings was enhanced under blue light compared to wild-type growth, providing phenotypic evidence for impaired CRY function. When these CRY1b RNAi rice plants were challenged with cadmium to induce melatonin, wild-type plants produced 100 ng/g fresh weight (FW) melatonin, whereas CRY1b RNAi lines produced 60 ng/g FW melatonin on average, indicating that melatonin biosynthesis requires the CRY photoreceptor. Due to possible feedback regulation, the expression of melatonin biosynthesis genes such as T5H, SNAT1, SNAT2, and COMT was elevated in the CRY1b RNAi lines compared to the wild-type plants. In addition, laminar angles decreased in the CRY1b RNAi lines via the suppression of brassinosteroid (BR) biosynthesis genes such as DWARF. The main cause of the BR decrease in the CRY1b RNAi lines seems to be the suppression of CRY rather than decreased melatonin because the melatonin decrease suppressed DWARF4 rather than DWARF. 相似文献
998.
Xiong S Xi B Wang C Zou G Fei L Wang W Qian Y 《Chemistry (Weinheim an der Bergstrasse, Germany)》2007,13(11):3076-3081
A facile L-cysteine-assisted route was designed for the selectively controlled synthesis of 1D and novel, interesting 3D CdS spherical nanostructures constructed from CdS nanorods (or nanopolypods) in a binary solution. By controlling reaction conditions such as the molar ratio between Cd(OAc)2 and L-cysteine and the volume ratio of the mixed solvents, the synthesis of various 3D architectural structures and 1D wirelike structures in large quantities can be controlled. This is the first reported case of the direct growth of novel 3D self-assemblies of CdS nanorods (or nanopolypods). The morphology, structure, and phase composition of the as-prepared CdS products were examined by using various techniques (X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), selected-area electron diffraction (SAED), high-resolution TEM, and Raman spectroscopy). On the basis of the results from TEM studies and our analysis, we speculate that in the present synthesis the L-cysteine dominates nucleation growth and the ethylenediamine (en)-dominated, oriented-assembly process. Interestingly, the products obtained show a gradient evolution in color from light-yellow to dark-yellow, which implies that their intrinsic optical properties change, possibly due to variations in their special morphologies and structures. This facile solution-phase L-cysteine-assisted method could be extended for the controlled preparation of other metal chalcogenides nanostructures with complex morphologies. 相似文献
999.
The hydrothermal reaction of Cd(OAc)2·H2O with 1,2-benzenedicarboxylate(1,2-BDC),imidazole and H2O resulted in the formation of a binuclear polymeric Cd(Ⅱ) complex {[Cd2(1,2-BDC)2(Im)4]·(H2O)}n which was then characterized by elemental analyses and single-crystal X-ray diffraction analysis.The crystal is of monoclinic system,space group P21/c with a = 14.6455(3),b = 9.3530(2),c = 23.7838(5) ,β = 106.6290(10)°,C112H104Cd8N32O36,Mr = 3373.47,V = 3121.64(11) 3,Dc = 1.795 g/cm3,F(000) = 1672,μ = 1.428 cm-1 and Z = 1.The final R = 0.0316 and wR = 0.0687 for 5045 reflections with I > 2σ(I).In the title complex,the two Cd(Ⅱ) ions are in different coordination environments with distorted octahedral and pengonal bipyramidal geometries,respectively.Two Cd polyhedra are linked together through one μ2-η1:η1 and one μ2-η1:η2 carboxylate groups from different 1,2-BDC ligands,giving rise to a binuclear Cd(Ⅱ) cluster,and such clusters are connected by bridged 1,2-BDC ligands to form a 2-D structure along the c axis.The inter-and intermolecular hydrogen bonds further connect the 2-D structures into a 3-D supramolecular network. 相似文献
1000.
A two-dimensional coordination polymer,[Cd(AIP)(Bpy)]n·nBpy,Was hydrother-mally synthesized by the reaction of hydrate cadmium acetate with 5-aminoisophthalic acid,lithium hydroxide,vanadiumpentoxide,sodium chloride and 2,2'-bipyridyl in water solution.It crystallizes in orthorhombic,space group C2221,absolute structure parameter 0.00(7),with a=15.336(4),b=22.390(6),C=14.257(3)(A),v=4896(2)(A)3,C28H21CdN5O4,Mr=603.90,Z=8,F(000)=2432,Dc=1.639 g/cm3,μ=0.939 mm-1,T=298(2)K,S=1.001,R=0.0296 and wR=0.08 13 for 5522 observed reflections(I>2o(I)).In the title complex,each 5-aminoisophthalate ligand bridges three cadmium(Ⅱ)ions to form a two-dimensional layer structure. 相似文献