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971.
972.
973.
The first passive mode locking of the continuous wave (cw) DCM dye laser is reported. Subpicosecond pulses as short as 0.68 ps were obtained over the spectral region from 655 to 673 nm from a simple linear cavity with no dispersion optimisation. The dye 1,3 Diethyl 4,2 quinolythiacarbocyanine iodide (DQTCI) was used as the saturable absorber. 相似文献
974.
Betzabé Sulbarán-de-Ferrer Marielena Aristiguieta Bruce E. Dale Alexis Ferrer Graciela Ojeda-de-Rodriguez 《Applied biochemistry and biotechnology》2003,105(1-3):155-164
Rice straw pretreated with liquid anhydrous ammonia was hydrolyzed with cellulase, cellobiase, and hemicellulase. Ammonia-processing
conditions were 1.5 g of NH3/g of dry matter, 85°C, and several sample moisture contents. There were four ammonia addition time (min)-processing time
(min) combinations. Sugars produced were analyzed as reducing sugars (dinitrosalicylic acid method) and by high-performance
liquid chromatography. Monomeric sugars increased from 11% in the nontreated rice straw to 61% of theoretical in treated rice
straw (79.2% conversion as reducing sugars). Production of monosaccharides was greater at higher moisture content and was
processing time dependent. Glucose was the monosaccharide produced in greater amounts, 56.0%, followed by xylose, arabinose,
and fructose, with 35.8, 6.6, and 1.4%, respectively. 相似文献
975.
976.
Philip W. Howard G. Richard Stephenson
Stephen C. Taylor
《Journal of organometallic chemistry》1989,370(1-3):97-109Homochiral 6-methoxy-substituted dienyltricarbonyliron complexes have been obtained from 1-methylcyclohexa-1,3-diene-5,6-diol (available via microbial oxidation of toluene) by complexation and removal of an allylic substituent with acids or with triphenylcarbenium tetrafluoroborate. A variety of optically active tricarbonyliron complexes have been produced from these compounds. The optical purity of the product and the stereochemistry of the complexation reaction have been determined. The high efficiency of chirality transfer during complexation of 5,6-dimethoxy-substituted dienes makes this method suitable as a general route to resolved organoiron complexes. 相似文献
977.
Allan E. Crease Harold Egglestone Nicola Taylor 《Journal of organometallic chemistry》1982,238(2):C5-C6
The tungsten complexes W(CO)4(NO)X, W(CO)3(NO)(PPh3)X and W(CO)2(NO)(PPh3)2X (X = Cl, Br and I) have been shown to be effective catalysts for the metathesis of 1,7-octadiene. 相似文献
978.
The stereoselective synthesis of cis-fused 1,4-epoxydecahydronaphthalenes from transannular reactions of medium-ring compounds is described. The carbon-13 nmr spectra of both are reported, and assignments of the various resonances have been made based on model compounds and off-resonance decoupling experiments. 相似文献
979.
[reaction: see text] Diels-Alder reactions of 3- and 5-halo-subsituted 2(H)-pyran-2-ones with both electron-rich and electron-deficient dienophiles afford stable and readily isolable bridged bicyclic lactone cycloadducts. These cycloadditions proceed with excellent regioselectivity and very good stereoselectivity. In contrast, Diels-Alder reactions of 4-halo-subsituted 2(H)-pyran-2-ones afford cycloadducts which are very prone to loss of bridging CO(2) and the subsequent formation of barrelenes ([2.2.2]cyclooctenes). Furthermore, these cycloadditions proceed with only moderate regio- and stereoselectivity. For both series of the 3- and 5-halo-subsituted 2(H)-pyran-2-ones and 4-halo-subsituted 2(H)-pyran-2-ones, the reactivity patterns do not significantly change between the halogens. The regio- and stereochemical preferences of the cycloadditions of halo-substituted 2(H)-pyran-2-ones are investigated computationally. Calculations were carried out on the transition states leading to the four possible regio- and stereoisomeric cycloadducts by using density functional theory (B3LYP/6-31G). These studies allow prediction of the regio- and stereoselectivity in these reactions which are broadly in line with experimental observations. 相似文献
980.
The main C(1) isomer of C(70)F(38) is shown by single-crystal X-ray analysis to contain four planar aromatic hexagons and four isolated C=C bonds, has two fluorines on the equator, and is related to C(2) C(70)F(38) by means of three 1,3-fluorine shifts. The C(1) and C(2) isomers thus parallel the T and C(3)/C(1) isomers of C(60)F(36) in containing three and four aromatic rings, respectively, and in the fluorine shift relationship. 相似文献