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本文是对旨在提高合成效率的化学反应选择性和金属有机化学关系的综述,按金属有机化合物的基元反应进行讨论。 相似文献
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过渡金属配合物的相转移反应 总被引:7,自引:0,他引:7
本文综述了相转移条件下过滤金属配合物催化有机合成的反应的进展。按羰基化反应、偶联反应、烃化反应、加成反应、还原反应及氧化反应等分别给予评述。 相似文献
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离分子负载金属催化剂在加氢反应的应用 总被引:1,自引:0,他引:1
本文以金属活性组分为序对各种高分子负载加氢催化剂的活性组分存在形式,高分子载体种类和加氢底物进行了归纳和总结,引用文献217篇。 相似文献
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过渡金属催化的烯烃羰基化反应现状与进展 总被引:5,自引:0,他引:5
阐述了烯烃羰基化反应在区域选择性和立体选择性方面的现状与最新进展,同时对羰基化反应新进展-超临界二氧化碳流体作为反应介质也作了综述。 相似文献
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综述了壳聚糖、甲壳素在污水处理、电化学、原子吸收光谱、高效液相色谱、吸光光度法中的应用。引用文献28篇。 相似文献
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煤烘玉米和饮水为介质地氟病区骨畸形病人全血尿多元素含量的分析 总被引:1,自引:1,他引:0
李福成 《广东微量元素科学》2000,7(3):37-41
采集了贵族个煤烘玉米为主要介质和河北2个饮水为介质氟病区内骨畸形病人的全血、尿、检测了其中8种元素含量,结果表明,贵州各氟病区少儿骨软化与成年骨硬化畸形病人的全血铝、钙、磷、铁和尿氟、铝均显著高于同龄对照组,尿磷均低于同龄对照组。少儿骨软化病人全血锌均下降,尿锌多下降。某水型氟病区骨软化经产妇尿氟、全血铜升高;骨软化少年全血铝显著升高,锌、铁下降,尿氟升高,尿锌,磷下降。海边的典型氟骨症病人全血、 相似文献
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P.N. Joshi N.K. Ramaswamy M.K. Raval T.S. Desai P.M. Nair U.C. Biswal 《Journal of photochemistry and photobiology. B, Biology》1993,20(2-3):197-202
Wheat seedlings, grown for 7 days in the light, were allowed to senesce in the light or dark, and the change in the photosystem II (PS II) photochemistry of chloroplasts isolated from the primary leaves of these seedlings was investigated. The decrease in oxygen evolution and the fast fluorescence results indicated that the impairment of PS II in the leaves of seedlings senescing in the light was different from that in the leaves of seedlings senescing in the dark. Thermoluminescence studies showed a structural modification in the QB protein of chloroplasts isolated from leaves senescing in the light and an alteration in the S state transition of chloroplasts isolated from leaves senescing in the dark. 相似文献
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Penicillins are the most frequently found antibiotic residues in milk, as they are commonly used for the treatment of bacterial infections in cows. In the present study, we introduce a method for the rapid detection of penicillin residues in raw milk based on the determination of glucose concentration in milk with a dual flow-through biosensor. The molar concentration of glucose in milk is typically over 500 times lower than the concentration of lactose and is highly dependent on the rate of lactose hydrolysis, which is catalyzed by β-galactosidase. Glucose concentrations in milk change with variation in the β-galactosidase activity. β-Galactosidase is an enzyme produced in the microbiota in milk and its activity is inhibited by benzylpenicillin. Spiking milk with benzylpenicillin lowers glucose concentrations in comparison to high-quality milk after short storage intervals. The presence of penicillin in the milk of treated animals resulted in decreased glucose concentrations in comparison with high-quality milk that contained no antibiotics. The glucose concentration in milk samples was followed by the system enabling the elimination of the effects of bacterial respiration in the output with reliable results in less than 1?min. 相似文献
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The accelerated growth of aquaculture has resulted in a series of harmful effects to human health. The widespread and unrestricted use of antibiotics in this industry, to prevent bacterial infections, leads to remaining amounts in the aquatic environment. This has resulted in the emergence of antibiotic-resistant bacteria in aquaculture environments, in the increase in antibiotic resistance in fish pathogens as well as in the transfer of these resistance determinants to human pathogens. Moreover, the use of large amounts of antibiotics may lead to the presence of residual antibiotics in fish tissue and fish products. Fluoroquinolones, tetracyclines, penicillins, sulphonamides and other antibiotics, exhibiting activity against both Gram-positive and Gram-negative bacteria, are widely used for the treatment and prevention of diseases in fish. An extended and comprehensive review on the recent analytical methodologies concerning antibiotic residues in fish reported in the literature is provided in the present article. Emphasis is given on sample preparation regarding isolation and purification, chromatographic conditions and method validation according to legislation. Results of published assays are comparatively presented and criticised. 相似文献
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为研究Graves病(GD)患者经^131I治疗后血浆和红细胞锌(Zn)含量的变化及其临床意义,采用原子吸收分光光谱法(AAS)和放射免疫分析法(Rn)分别检测了40例GD患者、20例经^131I治疗后甲状腺功能恢复至正常水平GD患者与30名健康人血浆和红细胞Zn的含量以及血浆甲状腺激素水平。结果表明,GD组红细胞Zn含量明显低于对照组(P<0.01);血浆Zn含量虽略低于对照组,但无统计学意义(P<0.05);且Zn与FT4呈明显负相关(P<0.01)、与TSH呈正相关(P<0.05)。GD治疗缓解组红细胞Zn明显高于治疗前(P<0.01),血浆Zn明显低于治疗前(P<0.05);红细胞Zn检测GD的敏感性与特异性分别为95.0%与96.7%。提示GD患者存在红细胞Zn含量改变,甲状腺激素可能干扰红细胞Zn的代谢,同时测定红细胞Zn可作为GD的临床诊断、治疗以及疾病转归的参考指标。 相似文献
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Skupińska Jadwiga Karpińska Monika Ołówek Maria Kasprzycka-Guttman Teresa 《Central European Journal of Chemistry》2005,3(1):28-39
The PdCl2/Fe/I2/Py catalytic system (Py-pyridine), reported to be highly active in the reaction of nitrobenzene carbonylation to ethyl phenylcarbamate
was studied. The present paper describes the role of catalyst components and its effect on the activity and selectivity of
the catalyst. The increase in the amount of PdCl2 in the system while retaining a constant level of the other catalyst components, results in the increase of both carbamate
and aniline yields. The increase in the amount of iron while retaining the other components constant, initially causes an
increase in the carbamate yield; however, at Fe: Pd ratios higher than 36, the carbamate yield remains constant. The change
in the amount of iron has no effect on the amount of aniline formed in the system. An increase in the amount of iodine in
the system while retaining the other components constant, results in a decrease in carbamate yield and a considerable increase
in the aniline yield of the reaction products. 相似文献
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Effect of plasticizer concentration on the hysteresis,tear strength and stress-relaxation characteristics of black-loaded rubber vulcanizate 总被引:1,自引:0,他引:1
N. K. Dutta 《Colloid and polymer science》1991,269(4):331-342
The effect of plasticizer concentration on the stress softening, tear strength and stress relaxation of black loaded bromobutyl rubber vulcanizate has been investigated. The stress softening in the rubber vulcanizate, an energy dissipative process at higher strain, may be explained primarily by changes that take place in the rubber phase of the filled vulcanizate. Increased plasticizer concentration leads to decrease in the equilibrium hysteresis. A quantitative relationship between energy density and hysteresis has been derived, which is applicable at and below the elongation at break. Increase in plasticizer concentration results in decrease in the effective diameter of the tip of the tear, which in turn decreases the tear strength. Rate of relaxation decreases with increase in the plasticizer concentration in the carbon-black-filled vulcanizate. 相似文献
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Calibration methods for microdialysis sampling were studied in the muscle and adipose tissue of rats. Both the delivery method and the no-net-flux method were used to determine the extraction efficiency (EE) of acetaminophen and caffeine in both tissues. There was no concentration dependence of the EE either in vitro or in vivo for either acetaminophen or caffeine. The EEs determined by the delivery and no-net-flux methods were not different. However, the EEs of both caffeine and acetaminophen determined in vitro were significantly higher than those determined in the muscle and adipose. This indicates that mass transfer in the tissue is the rate-determining factor for the EE in vivo. The relative difference between the EE in vitro and the EE in the muscle was smaller than the difference between the EE in vitro and the EE in the adipose. In addition, the EE in the muscle decreased more than the EE in the adipose after the animal was euthanized. This indicated that exchange between the extracellular fluid and plasma is the rate-determining step in mass transport relative to microdialysis sampling. This has a more significant effect on the EE in the muscle than the EE in the adipose. Both the delivery and no-net-flux methods can be used to calibrate microdialysis probes in the muscle and adipose. 相似文献
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Here we report on the role of oxygen in the evolution of radial heterogeneity in the fibre structure and properties of PAN fibres stabilized in air and vacuum at different temperatures. Modulus mapping by Nano-indentation showed heterogeneous modulus distribution in the fibres treated in air, while no variation in modulus was observed in fibres processed in vacuum. Raman spectroscopy and elemental analysis revealed that the temperature dependent oxygen diffusion from skin to core of the fibres assisted in the evolution of higher extent of sp2-hybridized carbons in the skin compared to core of the air treated samples. Conversely, no radial structure variations were observed in the vacuum treated fibres. Higher modulus in the skin of air-treated fibres was due to the formation of compact structures which was associated with the enhanced intermolecular interactions facilitated by the formation of C=C bonds within the polymer backbone, promoted by oxidative-dehydrogenation reaction. Supporting these observations, the fracture morphology examined by SEM showed a brittle fracture in the skin and ductile fracture in the core. 相似文献