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811.
With the diminution of fossil fuel resources and the increase in pollution, energy and environment have become a public concern. Mankind is in need of a new but clean energy resource. The use of hydrogen appears to be the answer. One of the technical challenges in hydrogen utilization is H2-storage. At present, materials for storing hydrogen are alloys such as LaNi5 and FeTi; the storage capacity is around 1.4 wt%, too low for practical application. Another problem with these alloys is…  相似文献   
812.
Although the asymmetric additions of diethylzinc to aldehydes have been extensively studied in the presence of chiral catalyst, most of the chiral ligands tested are b-amino alcohols1. In this report, the synthesis of chiral gamino alcohols 1-4 from the reaction of (+)-camphor and (-)-menthone with 2-lithiomethyl-6-methyl-pyridine or 2-picolly- lithium2, which give a single diasteromer as determined by 1H NMR with high yields (Scheme 1)3, and their application in the enantioselective additio…  相似文献   
813.
Transition-metal-catalyzed oligomerzation of ethylene is an important process to provide a-olefins in the C6~C20 range. In recent years, the catalytic behavior of late transition metal complexes containing bi- and tri-dentate ligands for oligomerization of ethylene to a-olefins has attracted much attention. When oligomerization of ethylene catalyzed by nickel diimine and Fe(II), Co(II) 2,6-bis(imino)pyridine catalysts, the oligomers with high average molecular weight were obtained1-5. Eth…  相似文献   
814.
Photodynamic therapy (PDT), using red light and photosensitizers (Sens ), is a promising new treatment for tumor. The naturally occurred hypocrellins,including hypocrellin A (HA) and hypocrellin B (HB,1), have been proposed as the potential photosensitizers for PDT. It has been the subject of many investigations to improve the red absorption and water-solubility of natural hypocrellins by the structural modifications1~3. In this paper, a new derivative 2 was synthesized from 1 and charact…  相似文献   
815.
Selective oxidation is an important unit process in petrochemistry and fine chemical industry. As a thermodynamically profitable reaction, selective oxidation of hydro- carbons usually takes place with a lot of side-reactions and a great deal of reaction heat at high temperature. To prevent the side-reactions and accelerate heat exchanges are two principal aims in catalytic oxidation1. Using the catalytic film not only can remove the target products from the reaction area in time, but also avo…  相似文献   
816.
Agricultural chemicals such as pesticides were extensively applied in the fields. Pesticides effectively protect the crops, only as long as they remain in the root zone of soil. In case a portion of the chemicals leaves root zone and especially leaches through soil pores. They may pollute groundwater and be a serious environmental problem1. This problem has got widespread concern in the world. In soils the fate of organic compounds such as pesticides is governed by hydraulic transport coupled…  相似文献   
817.
Nicotine, 3-(1-methyl-2-pyrrolidinyl)pyridine, the main alkaloid in tobacco products, has been well known for its addiction effect. Habitual smokers are usually maintaining nicotine concentration constant in their blood at about 10-15 ng/mL1. Therefore the interaction of nicotine and hemoglobin (Hb) is essential to be studied. Our recent study by accelerator mass spectrometry (AMS) has shown that nicotine could form adducts with Hb after in vivo administration, and there is a positive dose r…  相似文献   
818.
819.
Selenium is an essential element in living organism. It is reported that the selenosulfides have been transported in vivo in glutathione or coenzyme-A1. It is also discovered in low concentration in garlic2. In organic synthesis, selenosulfides are useful intermediates3. Several methods for the formation of sulfur-selenium bond have been reported. For example, the compounds including S-Se bond were prepared by chloroamination of thiols and selenols4; by heating the selenocyanate with thiols5…  相似文献   
820.
During the past years, there have been a lot of interests in the research of carbonaceous material as anode in lithium ion batteries1-3. Among them, natural graphite seems to be the most promising candidate for anode in lithium-ion batteries in terms of economy. Figure 1 The effect of Different Contents Figure 2 The Effect of Reacting Timeof Mixed Acid on Interlayer Distance On Interlayer DistanceHowever the raw natural graphite cannot be used for commercial purposes, because during proc…  相似文献   
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