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41.
A heated injection system for a microprocessor-controlled GC has been developed for the (GC)2 analysis of the volatile phase of whole smoke of a cigarette. Effects of injection port temperature and the presence of a Cambridge filter pad are demonstrated. Chromatograms are shown for smoke samples with and without a Cambridge Filter with the sample valve oven at 25°, 165° and 205°C. The use of a flame ionization and a nitrogen-phosphorous detector is illustrated. 相似文献
42.
Hans Zimmer Adel Amer Douglas Ho R. Palmer-Sungail 《Journal of heterocyclic chemistry》1991,28(6):1501-1510
The reaction pathway of 4-aroyl-3-hydroxy-2(5H)-furanones 1 with diamines depends on the nature of the amine as well as on the applied reaction conditions. Thus, the reaction of 1a-d with 5,6-diamino-1,3-dimethyluracil 5 led to the formation of two isomeric Schiff bases 7a-d and 8a-d . Conversely type 1 compounds reacted with 4,5-diaminopyrimidine 9 or 2,3-diaminopyridine 10 to form the mono acid-base adducts 11a and 11b respectively. When type 1 compounds were reacted with aliphatic diamines 13a-d or p-phenylenediamine and p-xylenediamine, respectively also an immediate formation of acid-base adducts 15a-f was observed. The reaction of a number of O-methylated type 1 compounds with 1,2-ethylenediamine afforded the novel seven-membered ring compounds 18a-d in good yields. The analogous reaction of O-alkylated 1a with o-phenylenediamine 2 or 2,3-diaminonaphthalene gave the expected tricyclic ring systems 19 or 20 . 相似文献
43.
Douglas F. Foster Barry S. Nicholls Anthony K. Smith 《Journal of organometallic chemistry》1982,236(3):395-402
Reactions of Rh6(CO)16 with bis(diphenylphosphino)methane (dppm) gave Rh6(CO)14(dppm), Rh6(CO)12(dppm)2, or Rh6(CO)10(dppm)3, depending upon the reaction conditions. Rh4(CO)10(dppm) may be obtained from the reaction of Rh4(CO)12 with dppm, but this derivative rapidly decomposes in solution to give Rh4(CO)8(dppm)2, Rh6(CO)14(dppm), and Rh6(CO)12(dppm)2. Ir4(CO)10(dppm) and Ir4(CO)8(dppm)2 have also been prepared, and their structures are discussed on the basis of infrared and 31P NMR spectroscopic data. 相似文献
44.
Geng J Ducati C Shephard DS Chhowalla M Johnson BF Robertson J 《Chemical communications (Cambridge, England)》2002,(10):1112-1113
A nanoscale ruthenium/gold bimetallic cluster of clusters has been used as a molecular precursor to produce pure ruthenium nanoparticles (seeds) as catalysts for the growth of carbon nanohorns (CNHs). 相似文献
45.
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
46.
A method is described for the determination of clomazone residues in surface water by high-performance liquid chromatography with UV detection. The method involves solid-phase extraction with C18 extraction tubes. Clomazone was separated on a C18 column with a mobile phase of methanol-water (65:35, v/v) at pH 4.0 and a flow-rate of 1.0 ml/min. After optimization of the extraction and separation conditions, the method was validated. The method developed can be used for determination of clomazone in surface water, at the limit of 0.1 mcirog/l set by the European Union drinking water directive, with a 400-fold preconcentration. 相似文献
47.
Schneider BB Douglas DJ Chen DD 《Rapid communications in mass spectrometry : RCM》2002,16(20):1982-1990
A multiple sprayer electrospray ion source for high-throughput analysis is described. The ion source is comprised of multiple electrospray capillaries, each with an ion lens located near the tip. The electric potentials applied to the ion lenses are used to control the sprayers. The use of ion lenses eliminates the need for mechanical blocking devices to selectively enable or disable the sprayers, and results in a less expensive and more reliable set-up. Sprayers can be enabled or disabled within approximately 50-250 ms when the lens potentials are controlled manually. For simultaneous operation of multiple electrospray capillaries, it is advantageous to orient the capillaries so that the spray from each passes directly in front of the entrance aperture of the mass spectrometer. 相似文献
48.
Michael T. Tseng Malcolm W. R. Reed Douglas M. Ackermann Dale A. Schuschke T. Jeffery Wieman Frederick N. Miller 《Photochemistry and photobiology》1988,48(5):675-681
Abstract— Photodynamic therapy disrupts blood flow to tumors and produces tumor necrosis. These effects may be due to a localized generation of singlet oxygen. The current studies used direct observations of the rat cremaster microvasculature to examine the vascular effects of PDT. The objective of the morphological examination was to delineate the structural basis for the altered blood flow in photodynamic therapy. Dihematoporphyrin ether given 30 min or 48 h prior to the experiment was activated with green light (wavelength530–560 nm, 120 J/cm2 ). After the in vivo activation the tissues were prepared for electron microscopy. Light alone induced little or no change in the luminal content or vessel wall. On exposure to activating light both acute (30 min) and long term (48 h) dihematoporphyrin ether pretreated samples displayed formation of luminal aggregates, granulocyte margination and migration, and endothelial cell and smooth muscle cell damage. The latter was more pronounced in the arterioles than the venules. Perivascular changes included interstitial edema and damage to striated myocytes. Some of the alterations such as interstitial edema may be transient; however, smooth and skeletal muscle cell injury are important in normal and tumor tissue necrosis after photodynamic therapy. 相似文献
49.
A new procedure for measuring time-resolved emission spectra has been implemented. This technique has subnanosecond time resolution combined with the sensitivity and dynamic range needed to cope with extremely weak luminescence. Using this method the emissions of Cr(NH3)2 (NCS)4? and Cr(NCS)63- in aqueous solution at room temperature have each been analyzed into two components. The fast component has a broad spectrum and is assigned to prompt fluorescence with lifetime below 100 ps. The slow component is dominated by phosphorescence but may include some delayed fluorescence. The phosphorescence lifetime is 5.5 ± 0.5 ns in Cr(NH3)2 (NCS)4? and 1.65 ± 0.1 ns in Cr(NCS)63-. Order of magnitude estimates have been derived for other photophysical parameters. 相似文献
50.
[chemical reaction: see text]. A direct access to (+/-)-5-epi-10-epi-vibsanin E is described, based on three key cycloaddition steps, a rhodium-catalyzed [4 + 3] cycloaddition, a heteronuclear [4 + 2] cycloaddition, and a photochemically induced [4 + 2] cycloaddition. 相似文献