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51.
Spatial and seasonal variations in attenuation of solar ultraviolet radiation in Lake Biwa, Japan 总被引:2,自引:0,他引:2
Seasonal changes in diffuse ultraviolet (UV) and visible light attenuations and inherent optical properties in the lake water were monitored at the pelagic and littoral shallow zones of Lake Biwa which features a broad range of optical conditions within a single large water body. We considered the absorption factors that affect UV attenuation, and clarified the contribution of the absorption of suspended particles and chromophoric dissolved organic matter (CDOM) by multiple regression analyses of the monitoring data. The variability of UV attenuations in the lake demonstrated a strong contrast between the pelagic and the shallow zones. The latter were characterized by turbid systems supplying suspended matter as well as CDOM, whereas the former was far from the turbid systems in the littoral zone or the lake bottom. In this lake, the regulation of UV and light attenuations is rendered competitive by the absorption of suspended particles and CDOM in the lake water, hence, the UV penetration has both spatial and temporal variability based on changes in the physical and biological condition of the lake. 相似文献
52.
Inside Back Cover: Plasmon‐Assisted Water Splitting Using Two Sides of the Same SrTiO3 Single‐Crystal Substrate: Conversion of Visible Light to Chemical Energy (Angew. Chem. Int. Ed. 39/2014)
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53.
Haino T Yamanaka Y Araki H Fukazawa Y 《Chemical communications (Cambridge, England)》2002,(5):402-403
The metal-induced regulation of fullerene complexation with double-calix[5]arene is described. The receptor shows strong binding to C70 only in the presence of Cu+. 相似文献
54.
[reaction: see text] D-Mannono-1,4-lactone was efficiently converted into L-ribose in eight steps. A key step of this synthesis is the cyclization of a gamma-hydroxyalkoxamate under Mitsunobu conditions. It is noteworthy that the O-alkylation product was obtained in 94% yield and that none of the N-alkylation product was detected in this cyclization. 相似文献
55.
Hiroyuki Inouye Yoshio Takeda Shinichi Uesato Kenichi Uobe Toshiro Hashimoto Tetsuro Shingu 《Tetrahedron letters》1980,21(11):1059-1062
Hydrangenoside A, isolated along with its three congeners from Hydrangea macrophylla, was proved to have a novel type of structure which is thought to be biosynthesized through an aldol-type condensation of secologanin with a unit formed by the shikimate-malonate route followed by decarboxylation. 相似文献
56.
The heats of fusion of methoxycarbonyl-benzenes (12 isomers) and -naphthalenes (32 isomers) have been determined by the differential scanning calorimetric method and the correlation of numbers and positions of methoxycarbonyl groups against the parameters of fusion (melting point, enthalpy and entropy) are discussed. The enthalpy—entropy relationship shows two correlation lines depending on the symmetry of the molecules including the positions of the substituents. 相似文献
57.
58.
Nakano H Takahashi K Okuyama Y Senoo C Tsugawa N Suzuki Y Fujita R Sasaki K Kabuto C 《The Journal of organic chemistry》2004,69(21):7092-7100
Cationic palladium (Pd)- and platinum (Pt)-phosphinooxazolidine catalysts 13a-c, 15a-d, 17a-c, and 19a-c were prepared from phosphinooxazolidine ligands 1-3, MCl(2) (M = Pd and Pt), and counterions, and the activities of the catalysts in the asymmetric Diels-Alder (DA) reactions of cyclic or acyclic dienes with imide dienophiles were investigated. These catalysts demonstrated high levels of catalytic activity. The cationic Pd-POZ complex 13c provided particularly excellent enantioselectivity (98% ee) in the DA reactions of cyclopentadiene with acryloyl-, crotonyl-, and fumaroyl-1,3-oxazolidin-2-ones (20a-c). 相似文献
59.
Novel spirocyclic trichothecanes, spirotenuipesine A and B, isolated from entomopathogenic fungus, Paecilomyces tenuipes 总被引:8,自引:0,他引:8
Kikuchi H Miyagawa Y Sahashi Y Inatomi S Haganuma A Nakahata N Oshima Y 《The Journal of organic chemistry》2004,69(2):352-356
Entomopathogenic fungi forming fruiting bodies have been employed as tonics and antitussives from ancient times. Paecilomyces tenuipes, which is also called Isaria japonica, is a very popular entomopathogenic fungus and is often considered a health food in northeast Asian countries such as China, Korea, and Japan. We cultivated the fruiting bodies of Paecilomyces tenuipes. Among the large-scale cultivations, fruiting body grown in barley grain contained two novel spirocyclic trichothecane derivatives, spirotenuipesine A (1) and B (2), and known trichothecane mycotoxins. Compounds 1 and 2 showed potent activity in neurotrophic factor biosynthesis in glial cells. The isolation of these compounds indicated that P. tenuipes is a promising source for producing various biologically active substances including trichothecanes. It is noteworthy that trichothecane mycotoxins are present in Paecilomyces tenuipes, which is typically used in medicinal health food. 相似文献
60.
In order to examine the reason why the magnitude of the synergistic effect observed in the extraction of lanthanoids(III) with a β-diketone and a monodentate Lewis base generally decreases along with increasing atomic number, the hydration number of the extracted species when lanthanoids(III) are extracted with TTA (2-thenoyltrifluoroacetone, HA) and benzoic acid (HB) into chloroform by Karl Fischer titration and the enthalpy change in complexation between LnA3 and HB by calorimetric titration were determined across the lanthanoid series at 25 °C.It has been concluded that since the decrement of entropy change caused by the change in the number of released water molecules and in the coordination number of lanthanoids(III) upon complexation is larger than the increment of the enthalpy change, the values of the second formation constants of the complexes decrease with increasing the atomic number across lanthanoid series so that the magnitude of the synergistic extraction decreases with increasing the atomic number. 相似文献