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991.
陕西煎茶岭矿床的稀土元素地球化学行为 总被引:10,自引:5,他引:5
研究表明煎茶岭矿床矿石的稀土组成明显不同于岩石。而镍和金矿床和稀土组成十分相似,富 轻稀土及明显的铕、铈、负异常,反映它们是从同一液中沉淀 。而铈和铕负异常程度差异表明镍矿形成于高温和相对还原的环境,金矿形成在低温和相对化的环境。矿化热液来源于酸性岩浆所分异的热液,成矿元素主要来自超基性岩。 相似文献
992.
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994.
Hetero-Atom Zeolite (Ⅱ)——Studies on the Crystal Structures of B-Si Pentasil zeolite Molecular Sieves
The crystal structure of B-Si pentasil zeolite molecular sieve was determined by means of the x-ray diffraction for polycrystalline samples and refined by Rietveld method.The parameters of the unit cell are e=19.983(1)A;b=19.773(1)A;c=13.303(1)A.Its space group is D2h1G-Pnma The framework topology found agrees with reported Si-Al ZSM-5zeolite molecular sieves.It is concluded from the structural determination that B is introduced into the framework of this sample. 相似文献
995.
Ming-xianPang 《计算数学(英文版)》2005,23(2):199-204
New estimates are provided for singular values of a matrix in this paper. These results generalize and improve corresponding estimates for singular values in [4]-[6]. 相似文献
996.
弱酸性介质中合成B-ZSM-5型分子筛 总被引:3,自引:2,他引:1
在弱酸性介质中,用四丙基溴化铵、氟化铵合成了B-ZSM-5型分子筛。由于晶化过程中无碱金属氢氧化物等强碱参与,B-ZSM-5型分子筛原粉为铵型,灼烧除掉NH3及有机模板剂后,直接转化为氢型,吸附吡啶后IR谱中有B酸和L酸中心存在。扫描电镜分析表明,B-ZSM-5分子筛晶体生长完美,晶体形貌随硼含量不同呈规律性变化。X射线衍射、红外光谱、X射线光电子能谱、差热分析等结果表明,硼原子位于ZSM-5分子筛骨架中。 相似文献
997.
核酸与蛋白质相互作用研究的新技术与新方法 总被引:1,自引:0,他引:1
蛋白质和核酸是组成生命的主要生物大分子,两者的相互作用构成了诸如生长、繁殖、运动、遗传和代谢等生命现象的基础.因此,研究它们间的相互作用是人们解开生命奥秘的关键所在,在学术及应用上都具有极其重要的意义.探讨蛋白质和核酸相互作用涉及到众多学科的技术与方法,是多学科的前沿交叉领域.总体上该方面工作尚处于起步阶段,深入研究有待于研究手段的进步与创新.本文从研究手段与分析方法上对近年来该领域所采用的技术及其最新进展进行了评述. 相似文献
998.
Wu Zhenyi Yang Sengen Lin Yongsheng Liu Jianyong Tian Ling Pang Zhaoyong Cheng Dadian Zhan Mengxiong 《化学物理学报(中文版)》2004,17(6):741-746
Fulerene complexe C60 Pd( Ph2PCH2PPh2)was perpared by the method of ligand substitution via the reaction of C60 with Pd(Ph2PCH2PPh2)2 under condition of a nitrogen atmosphere and refluxing,and the title compound was appraised and characterized by methods of elemental analysis,FT-IR,UV-vis,XPS and XRD. The results showed that the structure of purposeful product was that the Ph2PCH2PPh2 took up two coordination sites of the central metal,and C60 took up another two sites in σ-π feeback pattern. The porperties on photoelectricity,redox and thermostability of the title complexe were studied. The results of studying on photoelectricity showed that the photovoltaic effect of(n+n)heterojunction electrode formed by C60Pd(Ph2PCH2PPh2)/ GaAs was supper,especially in the BQ/ H2Q redox couple,and the greatest value of photovoltaic potential was up to 174 mV. The photovoltaic performance of C60Pd(Ph2PCH2PPh2)/GaAs electrode at 1 μm for thickness of C60Pd(Ph2PCH2PPh2)film was the best. 相似文献
999.
Zeyang Pang Qizhen Li Yuexiao Jia Weixiao Yan Jie Qi Yuan Guo Fupin Hu Dejian Zhou Xingyu Jiang 《Chemical science》2021,12(44):14871
Infections caused by multidrug-resistant (MDR) bacteria are an increasing global healthcare concern. In this study, we developed a dual-ligand-functionalised Au25(SR1)x(SR2)18−x-type gold nanocluster and determined its antibacterial activity against MDR bacterial strains. The pyridinium ligand (SR1) provided bactericidal potency and the zwitterionic ligand (SR2) enhanced the stability and biocompatibility. By optimising the ligand ratio, our gold nanocluster could effectively kill MDR Gram-positive bacteria via multiple antibacterial actions, including inducing bacterial aggregation, disrupting bacterial membrane integrity and potential, and generating reactive oxygen species. Moreover, combining the optimised gold nanocluster with common antibiotics could significantly enhance the antibacterial activity against MDR bacteria both in in vitro and animal models of skin infections. Furthermore, the fluorescence of the gold nanocluster at the second near-infrared (NIR-II) biological window allowed for the monitoring of its biodistribution and body clearance, which confirmed that the gold nanoclusters had good renal clearance and biocompatibility. This study provides a new strategy to combat the MDR challenge using multifunctional gold nanomaterials.A NIR-II fluorescent Au25 nanocluster capped with optimal dual functional ligands can effectively aggregate and kill Gram-positive drug-resistant bacteria while maintaining good biocompatibility. 相似文献
1000.
A great concern has been raised regarding the issue of fluoroquinolones(FQs) in the environment. In this work, the transformation of FQs by commonly used oxidant permanganate(Mn(VII)) in the absence and presence of humic acid(HA), ubiquitously existing in aquatic environments, was systematically investigated. Here, the catalytic role of in-situ formed MnO2 on Mn(VII) oxidation of FQs depending on solution pH and co-existing substrates was firstly reported. It was interestingly found t... 相似文献