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春节前后,吉安市遭遇到罕见的冰冻雨雪灾害天气,连续出现了低温、阴雨和雨夹雪,成为全省灾情最严重地区之一.特别是1月25日以后,出现了持续大范围的雨雪冰冻天气.冰冻损坏了市区的电网,压垮了树枝,封锁了道路和桥梁. 相似文献
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收集了2010年7月~2011年6月世界塑料工业的相关资料,介绍了2010~2011年世界塑料工业的发展情况,提供了世界塑料产量、消费量及全球各类树脂的需求量及产能情况。按通用热塑性树脂(聚乙烯、聚丙烯、聚氯乙烯、聚苯乙烯、ABS树脂),工程塑料(尼龙、聚碳酸酯、聚甲醛、热塑性聚酯、聚苯醚),特种工程塑料(聚苯硫醚、液晶聚合物、聚醚醚酮),通用热固性树脂(酚醛、不饱和聚酯树脂、环氧树脂、聚氨酯)不同品种的顺序,对树脂的产量、消费量、供需状况及合成工艺、产品应用开发、树脂品种的延伸及应用的进一步扩展等技术作了详细介绍。 相似文献
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萜类化合物具有可观的经济价值,但是目前的生产过程复杂、产量低。酿酒酵母甲羟戊酸途径为萜类化合物的合成提供直接前体,因此酿酒酵母细胞具有合成异源萜类化合物的天然优势。对酿酒酵母甲羟戊酸途径的清晰认识是对其进行有效利用的基础,本文从代谢途径、关键酶的特点和全局调控机制3个方面对该途径进行了介绍。从代谢途径的构建和优化、模块与底盘细胞的适配、模块构建及组装方式的角度概述了酿酒酵母细胞异源合成单萜、倍半烯萜、二萜、三萜类化合物的研究进展。指出实现酿酒酵母高效合成萜类化合物所需要解决的基础问题是对酿酒酵母甲羟戊酸途径进行更为全面了解和对萜类化合物的天然代谢途径进行明确解析;另外,合成生物学的进一步发展也将为此提供应用基础。 相似文献
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我公司回转窑规格为Φ4.0m×60m.窑内使用的耐火砖为镁铬砖、隔热尖晶石、蓝晶石和黏土砖以及硅莫砖.镁铬砖规格为(81×90×150×200)mm,其它耐火砖规格皆为(81×90×200×200)mm.尽管每个品种的砖品质相同,但由于在镶砌和使用过程中方法不同,寿命有长有短.通过多年实践,现总结如下. 相似文献
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《日用化学品科学》编辑部 《日用化学品科学》2008,31(6)
2006年12月7日~2006年12月8日化妆品化学家年会在美国纽约举行,该年会为化学品供应商提供了参与REACH法规的机会.REACH法规的实施引起了业界的广泛关注,来自世界各地的著名化学品及化妆品公司对REACH法规的实施所带来的一些问题,以及新原料、新技术进行了交流.会议主要对就REACH法规、制造及规模化和神经美容品等方面展开了研讨. 相似文献
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建设创新型国家是我们中华民族的历史责任。“自主创新、重点突破、支撑发展、引领未来”的16字方针应当成为我们未来创新活动的指南。建设创新型国家把自主创新放在首位,并提出了引领未来的高标准要求。钢铁科技创新必须突出重点,抓住创新成果产业化这个关键,支撑起行业和国民经济的发展。 相似文献
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相比已经完善丰富的开采和勘探技术,油气的运输以及储存却仍然存在不足之处。我国对能源安全提出更加严格要求的同时,对区域经济的发展规划也有足够重视。因此,保障油气管道的安全则成为了我国能源安全战略的重中之重。在阐释油气管道现阶段在储运安全保障技术发展状况的基础上,分析了现存的问题及解决问题的手段,并指出未来可能使用的目标策略,为今后研究者提供一定程度上的借鉴经验。 相似文献
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Solid solutions of diphosphates of zinc and copper and of zinc and cobalt were synthesized from mixtures of pure diphosphates at temperatures up to 1000°C. Their X-ray diffractometry patterns varied continuously from one end member to the other. Solid solutions of orthophosphates of composition Zn3−x Cox(PO4 )2, with x = 0.4–1.6, were formed at temperatures up to 950°C; all exhibited the structure of γ-Zn3 (PO4 )2. Solid solutions of orthophosphates of composition Zn3−x Cux (PO4 )2 exhibited more-complex behavior. At 1000°C and copper contents of 20–80 mol%, a phase that is related to Cu3 (PO4 )2, termed here the "ε-phase," predominated. At 850°–950°C and in the region from 20 mol% to ∼33 mol% of copper, the solid solutions (the "η-phase") adopted the structure of graftonite. At 800°–900°C and 10–15 mol% of copper, the solid solutions exhibited a new structure (the "δ-phase"), which we found to be related to the mineral sarcopside. At temperatures 950°C, the solutions that contained 5–15 mol% of copper (the "β-phase") had the structure of β-Zn3 (PO4 )2, whereas at 800°–850°C, solutions with 5 mol% of copper (the "-phase") exhibited the structure of γ-Zn3 (PO4 )2. Attempts to synthesize Cu+ ZnPO4 and Cu+ Cu2+ Zn3 (PO4 )3 were unsuccessful. 相似文献
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膜的污染和劣化及其防治对策 总被引:25,自引:0,他引:25
较为系统地介绍了膜污染和劣化的定义和特点,因膜污染和劣化而造成的膜性能变化,以及如何预防、减少或清除膜污染和劣化的一些通用方法。 相似文献
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填料-橡胶的化学和物理作用及补强ⅡN330,SiO2,n-SiO2和n-SiO2/KH-846与NR 总被引:1,自引:0,他引:1
研究了填料-橡胶的相互作用。发现N330-NR间的相互作用。n-SiO2(粒径:15nm)/KH-846-NR间的相互作用,都是化学作用占优势(>80%),化学作用对补强的贡献率都大于90%;无偶联剂KH-846时,n-SiO2和SiO2(粒径:15.8nm)与NR都无化学作用,只有物理交联,由于隔离作用,都降低硫化体系与橡胶相互作用的化学交联密度,但n-SiO2的物理交联密度是SiO2的2.6倍,对补强的贡献是SiO2的1.9倍,也是n-SiO2/KH-846体系的61%。 相似文献
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Michael P. Badart Emma M. Barnes Andrew P. Cording Selena C. L. Gilmer Ian D. Billinghurst Veera V. Shivaji R. Edupuganti Prof. Guillaume Lessene Abigail R. Bland Rebekah L. Bower Zohaib Rana Scott A. Ferguson Helen K. Opel Reading Prof. Gregory M. Cook Prof. Rhonda J. Rosengren Prof. Kurt L. Krause Dr. Allan B. Gamble Prof. John C. Ashton Dr. Bill C. Hawkins 《ChemMedChem》2021,16(8):1308-1315
A second-generation enantiospecific synthesis of spiroleucettadine is described. The original reported antibacterial activity was not observed when the experiment was repeated on the synthetic samples; however, significant anti-proliferative activity was uncovered for both enantiomers of spiroleucettadine. Comparison of the optical rotational data and ORD-CD spectra of both enantiomers and the reported spectrum from the natural source have not provided a definitive answer regarding the absolute stereochemistry of naturally occurring spiroleucettadine. Efforts then focussed on alteration at the C-4 and C-5 positions of the slightly more active (−)-spiroleucettadine. Ten analogues were synthesised, with three analogues found to possess similar anti-proliferative profiles to spiroleucettadine against the H522 lung cancer cell line. 相似文献
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The composition and solubility properties of eight ammonium and potassium orthophosphites and hypophosphites were determined to evaluate the potential of these classes of materials for increasing the plant nutrient content of liquid fertilizers. Phase relationships for the systems (NH4)2O-P2O3-H2O, K2O-P2O3-H2O, (NH4)2O-P2O-H2O, and K2O-P2O-H2O were determined along with the crystallographic properties (X-ray and optical) of the solid phases. Toxicity and phosphite response was tested in greenhouse experiments for the compounds. 相似文献
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文章采用离子色谱法/电导检测器,测定了蔬菜水果样品中的硝酸盐和亚硝酸的含量。实验选取并优化样品前处理方法,获得无色透明的溶液后,经0.45μm过滤器过滤后得到待测液,最后自动进样,离子色谱法进行样品测定,以10 mmol/L KOH溶液为淋洗液,相对标准偏差:NO3-为0.38%,NO2-为0.54%;回收率:NO3-为98.8%~99.7%,NO2-为98.6%~99.9%。本方法操作简便快速,且具有仪器稳定性好、测定结果准确可靠的特点。在被测定蔬菜水果中,硝酸盐和亚硝酸盐含量都在较低浓度水平,NO3-:16.8~21.9 mg/kg,NO2-:0.0887~0.164 mg/kg。最后讨论了几种蔬菜水果样品储藏过程中硝酸盐与亚硝酸盐的含量变化情况。 相似文献
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Tetraalkynylated and Tetraalkenylated Benzenes and Pyridines: Synthesis and Photophysical Properties
Peter Ehlers Ani Hakobyan Antje Neubauer Stefan Lochbrunner Peter Langer 《Advanced Synthesis \u0026amp; Catalysis》2013,355(9):1849-1858
Tetra(arylalkynyl)pyridines and tetra(arylalkenyl)pyridines and their benzene analogues were prepared by palladium‐catalyzed cross‐coupling reactions from the commercially available chlorinated substrates in good to excellent yields. The photophysical properties of selected compounds were investigated and compared to each other. Very good fluorescence quantum yields were observed, especially for the pyridine derivatives. 相似文献
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《Ceramics International》2016,42(13):14313-14325
Bioactive glasses and glassceramics have been used in both bone repair and tissue engineering applications. An important feature of bioactive glasses and glassceramics, which enables them to be used for desired application, is their biological activity. This activity is manifested by the ability of these materials to form a stable bond with bone tissue (bioactivity) and, in some cases, their ability to promote/initiate osteogenesis (osteoinductivity). A stable material-bone bonding (i.e. bioactivity) results from specific material surface reactions leading to hydroxyapatite (HAp) formation on the material surface. Bioactivity of materials is often evaluated in vitro and the ability of materials to form HAp-like surface layer is usually studied after immersion/incubation of materials in simulated body fluid (SBF). Biological activity of materials can be also defined as their ability to induce specific cell responses leading to faster regeneration of bone tissue. It may be manifested by materials supporting bone cell attachment, proliferation and differentiation (biocompability/osteconductivity), and/or by materials inducing/promoting the expression of multiple bone-related genes that drive osteogenesis (osteoinductivity). Osteoinductivity is often verified in vivo by the materials capability to form bone at etopic (i.e. extraskeletal) sites. However, a lot of in vitro call-based experiments are now offered to determine osteoinductive properties of biomaterials. This review focuses on the silica-based glasses and glass-ceramics, in particular, the sol-gel derived ones, and summarizes their bioactivity and osteoinductivity as major determinants of their biological activity. We highlight the chemistry of bioglasses and glassceramics that affects not only the formation of a stable implant/bone bonding by HAp layer, but also drives the cell response in vitro and in vivo. 相似文献