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排序方式: 共有61条查询结果,搜索用时 15 毫秒
1.
Antonio Alberola Rebecca J. Collis Robert J. Less Jeremy M. Rawson 《Journal of organometallic chemistry》2007,692(13):2743-2749
A general three-step synthesis to a range of benzo-fused-1,3,2-dithiazolylium salts bearing both electron-withdrawing (CN) and electron-donating (Me) groups is described. This methodology has also been extended to pyridyl derivatives and offers a potential route to a diversity of 1,3,2-dithiazolylium rings and their corresponding 1,3,2-dithiazolyl free radicals. The key steps in the reaction are treatment of a substituted 1,2,-dichlorobenzene with two equivalents of [tBuS]Na, followed by chlorination to yield the corresponding bis(sulfenyl chloride). Subsequent ring closure with Me3SiN3 yields the target 1,3,2-dithiazolylium ring system in good yield. The preparation and crystal structures of 3′-methyl-benzo-1,3,2-dithiazolylium chloride and 3′-methyl-benzo-1,3,2-dithiazolyl are described and the electronic properties of the radical examined through EPR spectroscopy, DFT calculations and variable temperature magnetic susceptibility measurements. 相似文献
2.
《Arabian Journal of Chemistry》2022,15(11):104262
This review critically evaluates the plastic accumulation challenges and their environmental (primarily) and human (secondarily) impacts. It also emphasizes on their degradation and fragmentation phenomena under marine conditions. In addition, it takes into account the leachability of the various chemical substances (additives) embedded in plastic products to improve their polymeric properties and extend their life. Regardless of their effectiveness in enhancing the polymeric function of plastic products, these additives can potentially contaminate air, soil, food, and water. Several findings have shown that, regardless of their types and sizes, plastics can be degraded and/or fragmented under marine conditions. Therefore, the estimation of fragmentation and degradation rates via a reliable developed model is required to better understand the marine environmental status. The main parameter, which is responsible for initiating the fragmentation of plastics, is sunlight/UV radiation. Yet, UV- radiation alone is not enough to fragment some plastic polymer types under marine conditions, additional factors are needed such as mechanical abrasion. It should be also mentioned that most current studies on plastic degradation and fragmentation centered on the primary stages of degradation. Thus, further studies are needed to better understand these phenomena and to identify their fate and environmental effects. 相似文献
3.
利用体外细胞病变效应(CPE)法,发现菊科千里光属植物麻叶千里光(Senecio cannabifoliusLess.)挥发油对呼吸道合胞病毒(RSV)和单纯疱疹病毒Ⅰ型(HSV-Ⅰ)致HeLa细胞病变有显著的抑制作用,能不同程度地延缓副流感病毒、柯萨奇病毒B3、腺病毒Ⅲ型和流感病毒致细胞病变作用。为进一步确定麻叶千里光挥发油抗病毒的活性成分,经气相色谱-质谱联用技术对其进行了成分分析。麻叶千里光挥发油得率0.22%(mL/100g),从中初步鉴定了26种化合物,占挥发油总量的88.47%,主要为正十六(烷)酸(27.01%)、胡萝卜次醇(13.73%)、9,12-十八碳二烯酸(9.99%)、α-蒎烯(9.28%)和β-蒎烯(5.58%)。在鉴定出的化合物中,萜烯占47.42%,脂肪酸类占37.61%,其它成分仅占3.44%,故提示麻叶千里光挥发油中高含量的萜烯和脂肪酸类可能与其抗病毒活性有关。 相似文献
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火检系统是火力发电机组不可缺少的重要组成部分,油枪火检的可靠性对提高机组主辅设备的可靠性和安全性具有十分重要的作用,火检的偷窥是困扰发电厂安全生产的一大难题,本文通过分析大唐林州热电双强少油点火火检存在的问题,以及影响火检偷窥的一系列因素,提出了改造双强少油点火火检系统的方法和实施步骤以及要求,并对所产生的经济效益进行了估算,改造对机组的安全性、可靠性影响做了定性分析. 相似文献
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Claudia Villanueva‐Cañongo Nury Pérez‐Hernández Beatriz Hernández‐Carlos Ernestina Cedillo‐Portugal Pedro Joseph‐Nathan Eleuterio Burgueño‐Tapia 《Magnetic resonance in chemistry : MRC》2014,52(5):251-257
Chemical investigation of the aerial parts of Senecio polypodioides lead to the isolation of the new eudesmanoid 1β‐angeloyloxyeudesm‐7‐ene‐4β,9α‐diol ( 1 ) and the known dirhamnosyl flavonoid lespidin ( 3 ), while from roots, the known 7β‐angeloyloxy‐1‐methylene‐8α‐pyrrolizidine ( 5 ) and sarracine N‐oxide ( 6 ), as well as the new neosarracine N‐oxide ( 8 ), were obtained. The structure of 1 and 8 was elucidated by spectral means. Complete assignments of the 1H NMR data for 5 , 6 , sarracine ( 7 ), and 8 were made using one‐dimensional and two‐dimensional NMR experiments and by application of the iterative full spin analysis of the PERCH NMR software. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
8.
二烷氨基乙醇羧酸酯对瓜叶菊生长及生理活性的影响 总被引:13,自引:0,他引:13
在瓜叶菊定植后,喷不同浓度的二烷氨基乙醇羧酸酯,可明显增加植株叶片的蛋白质,核酸及叶绿素含量,提高其过氧化物酶和硝酸还原酶活性,增强光速度,其叶面积比对照减小,但厚度明显增加,可比对照提前一周开花,增加开花数,且延长花期,并能提高植株的抗冷性和抗病性,其最佳施用浓度为5.0mg/kg。 相似文献
9.
麝香百合、仙客来、瓜叶菊花芽分化的调控 总被引:11,自引:3,他引:8
复合生长调节剂处理对麝香百合等花芽的分化有明显的作用。其中A1,A2可促进麝香百合花工芽的分化,A2效果较A1好,经A2处理后,百合开花率达100%,同时使植株的开花数增加了1倍,花径增长1倍;B1,B2明显促进仙客来花芽分化,B2效果较B1好,经B2处理后,处理仙客来较对照植株的花蕾数增加41%;C1,C2明显促进瓜叶菊花芽分化,其中C1处理的瓜 叶菊较对照植株的花蕾数增加52%。 相似文献
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