首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 15 毫秒
1.
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   

2.
Anaphylaxis is a severe, acute, life-threatening multisystem allergic reaction resulting from the release of a plethora of mediators from mast cells culminating in serious respiratory, cardiovascular and mucocutaneous manifestations that can be fatal. Medications, foods, latex, exercise, hormones (progesterone), and clonal mast cell disorders may be responsible. More recently, novel syndromes such as delayed reactions to red meat and hereditary alpha tryptasemia have been described. Anaphylaxis manifests as sudden onset urticaria, pruritus, flushing, erythema, angioedema (lips, tongue, airways, periphery), myocardial dysfunction (hypovolemia, distributive or mixed shock and arrhythmias), rhinitis, wheezing and stridor. Vomiting, diarrhea, scrotal edema, uterine cramps, vaginal bleeding, urinary incontinence, dizziness, seizures, confusion, and syncope may occur. The traditional (or classical) pathway is mediated via T cells, Th2 cytokines (such as IL-4 and 5), B cell production of IgE and subsequent crosslinking of the high affinity IgE receptor (FcεRI) on mast cells and basophils by IgE-antigen complexes, culminating in mast cell and basophil degranulation. Degranulation results in the release of preformed mediators (histamine, heparin, tryptase, chymase, carboxypeptidase, cathepsin G and tumor necrosis factor alpha (TNF-α), and of de novo synthesized ones such as lipid mediators (cysteinyl leukotrienes), platelet activating factor (PAF), cytokines and growth factors such as vascular endothelial growth factor (VEGF). Of these, histamine, tryptase, cathepsin G, TNF-α, LTC4, PAF and VEGF can increase vascular permeability. Recent data suggest that mast cell-derived histamine and PAF can activate nitric oxide production from endothelium and set into motion a signaling cascade that leads to dilatation of blood vessels and dysfunction of the endothelial barrier. The latter, characterized by the opening of adherens junctions, leads to increased capillary permeability and fluid extravasation. These changes contribute to airway edema, hypovolemia, and distributive shock, with potentially fatal consequences. In this review, besides mechanisms (endotypes) underlying IgE-mediated anaphylaxis, we also provide a brief overview of IgG-, complement-, contact system-, cytokine- and mast cell-mediated reactions that can result in phenotypes resembling IgE-mediated anaphylaxis. Such classifications can lead the way to precision medicine approaches to the management of this complex disease.  相似文献   

3.
This standard specifies the classification, shape, dimension, technical requirements, test method, inspection rules, packing, marking, transportation, storage and quality certification of fireclay refractory bricks for hot blast stove.  相似文献   

4.
The primary sex pheromone of the yellowheaded spruce sawfly,Pikonema alaskensis (Rohwer) (Hymenoptera: Tenthredinidae), was found to include a series of straight-chain hydrocarbon dienes, all with the double bonds in the 9 and 19 positions and all with the (Z, Z) configuration. The major components, of 29, 31, 33, 35, and 37 carbon atoms, were synthesized. In the field and the greenhouse, the synthetic dienes were far above control levels in activity but, at least during the first hours of bioassay, were somewhat less active than the female-derived materials on a weight basis. In the field, a mixture of all five synthetic dienes, in the proportions found in the females, was more attractive than any single one, on a mole basis. In addition, (Z, Z)-9,19 dienes of 28, 30, 32, 34, 36, 38, and 39 carbons have been detected in females in minor amounts. The first five were bioassayed, and each was found to be similar in activity to the 35-carbon component when compared on a weight basis. The synthetic dienes, while active by themselves, were strongly synergized by two, more polar, Florisil fractions derived from females. Experimental design considerations are discussed.  相似文献   

5.
以中低温煤焦油轻油和重油为实验原料,采用常压蒸馏获得170~200℃、200~240℃、240~270℃、270~300℃、300~320℃、320~340℃、340~360℃和360~390℃煤焦油馏分油;利用配有油品加氧制冷进样系统的ICP-OES测定了21种微量元素在馏分油中的含量,考察了不同馏分油中元素的分布情况。研究表明:在原煤焦油中,未发现Ag、Mg、Mo、Na、Ni、Fe、Mn、Cr及Ti元素,含量较高的元素有Sn、P、Al、Pb、Si,其中Sn元素在轻油和重油中的含量分别为11.78μg/g和14.04μg/g;在所有馏分油中,未发现Al、Mo、Fe、Mn、Cr及Ti元素,含量比较高的元素有Si、Sn、Na、Zn、Pb,特别是Si、Na、Sn、Zn、Ni、Pb及B元素可以有效富集于馏分油中。可能的原因是Ca、Fe、Mg、Al等金属以不同的盐类形态存在,在煤焦油脱水及<170℃蒸馏过程中,这些金属盐类会被部分带出,导致其在馏分油中的含量未富集或未检出;通过关联金属元素在馏分油中的分布与其组成的关系,馏分油中元素的分布可能与酚类化合物、杂环化合物和蒸馏温度等相关。酚类化合物及杂环化合物可能与Ag、B、Cu、Mo、Sn、Na、Zn、Ca、Pb等金属形成络合物或卟啉配合物,蒸馏温度一方面可以破坏Sn、Cd、Pb、Zn、Cu、Ca、Pb等元素在馏分油中的结合力,另一方面也可以促进这些元素与馏分油中的含氧、含氮等化合物更好地发生化合反应,进而影响金属元素在馏分油中的含量分布。  相似文献   

6.
王强 《中国陶瓷》2006,42(1):34-35
匋、陶、窑(窯)上古皆读成舌头音,意义又相通,实际为一个意义上先后产生的几个形体不同的字,先民以陶(匋)既称呼窑灶,又指窑灶出品之物,又指制作陶器;坏(坯)、瓶、瓬、瓿、甂、缶、钵、皿、杯(盃)、盆(瓫)均指窑灶所出之物或后世模仿窑灶出品之物,其字皆由重唇音演变而来,亦为同胞兄弟的同源词。  相似文献   

7.
抗菌防腐剂(Ⅰ)—抗菌防腐剂的历史、定义与分类   总被引:6,自引:0,他引:6  
简要回顾了抗菌防腐剂的发展历程,进一步明确了杀菌剂,抑菌剂,抗菌剂,防腐剂,防霉剂,消毒剂,杀生剂,保鲜剂,抗生素的概念。同时,结合抗菌防腐剂的发展在对抗菌防腐剂按无机物,有机物和天然物分类的基础上,进一步又按化学结构和官能团将抗菌剂分为有机金属,有机卤代物,醇,酚,醚,醛,酮,醌,酸,酯,含氮类,含硫类,有机磷,有机砷类以及杂环类等。  相似文献   

8.
纳米材料被誉为21世纪的新材料,广泛应用于化工、电子、国防、陶瓷等领域.传统的纳米材料制备方法面临粒径控制较困难、批次间重复性差,存在放大效应等不足.过程强化技术是化学工程学科的研究前沿和热点方向之一,旨在通过在生产过程中采用新工艺、新设备等手段,实现缩减操作单元、减小设备体积、提高生产能力及能量利用效率的目的,是实现...  相似文献   

9.
Alkaline extracts (soapstocks) from canola, corn, cottonseed, peanut, soybean, and sunflower oil refining were acidified, and identities and concentrations of the low-molecular weight organic components of the resulting acid waters were determined by gas chromatography, followed by mass spectroscopy, and by high-performance liquid chromatography. The main components of each acid water sample, in order of decreasing concentration and after omitting the fermentation product lactic acid, were phosphoric acid, α-glycerophosphate, and glycerol from canola;myo-inositol, phosphoric acid, α-glycerophosphate andmyo-inositol-1-phosphate from corn; glycerol, α-glycerophosphate,myo-inositol-1-phosphate, and β-glycerophosphate from cottonseed; phosphoric acid, glycerol, andmyo-inositol from peanut; α-glycerophospho-1-myo-inositol,myo-inositol-1-phosphate, α-glycerophosphate, and glycerol from soybean; and α-glycerophosphate, glycerol,myo-inositol-1-phosphate, and β-glycerophosphate from sunflower.  相似文献   

10.
铋系半导体材料具有特殊的层状结构以及合适的带隙,具有良好的可见光响应能力以及稳定的光化学特性,作为一类新型的环境友好型光催化剂在环境修复与解决能源危机等领域受到广泛关注,已成为近年来的研究热点。然而,铋系半导体光催化剂距离实际大规模应用仍存在一些亟需解决的问题,如光生载流子复合率高、对可见光谱的响应范围有限、光催化活性较差、还原能力较弱等。本文首先介绍了铋系半导体材料的典型特征、制备方法与反应机理,在此基础上着重阐述了铋系半导体光催化在形貌调控、构建异质结、离子掺杂、碳质材料掺杂、贵金属沉积、染料敏化等改性手段的研究进展以及在降解水体污染物、杀菌消毒、空气净化、制氢、还原CO2、有机合成等领域的应用成果。最后对铋系半导体光催化剂的未来前景做出展望,指出其未来的研究方向应致力于从多手段耦合改性、拓展其应用领域以及深入探究反应机理等方面开展。  相似文献   

11.
国内乙醛酸衍生产品的现状与展望(一)   总被引:2,自引:0,他引:2  
本文结合国外情况对尿囊素、香兰素、乙基香兰素、对甲氧基苯甲醛、儿茶醛、胡椒醛、扁桃酸、二苯基乙酸、对羟基苯乙酸、苯并二呋喃酮系列化合物、苯甘氨酸、对羟基苯甘氨酸、泛酸钙、2-羟基喹(?)啉、2-羟基膦酰基乙酸等乙醛酸下游产品的国内市场与科研情况做了较详细地论述。预计,我国目前GA的总需求量约为9000t/a,消费构成大致为,苯甘氨酸类占42.3%、尿囊素占31.6%、芳香醛占20%、其它占6.1%,进口量约3000~4000t/a。  相似文献   

12.
Rheumatoid arthritis (RA) is a systemic autoimmune disease that primarily affects the joints. Organokines can produce beneficial or harmful effects in this condition. Among RA patients, organokines have been associated with increased inflammation and cartilage degradation due to augmented cytokines and metalloproteinases production, respectively. This study aimed to perform a review to investigate the role of adipokines, osteokines, myokines, and hepatokines on RA progression. PubMed, Embase, Google Scholar, and Cochrane were searched, and 18 studies were selected, comprising more than 17,000 RA patients. Changes in the pattern of organokines secretion were identified, and these could directly or indirectly contribute to aggravating RA, promoting articular alterations, and predicting the disease activity. In addition, organokines have been implicated in higher radiographic damage, immune dysregulation, and angiogenesis. These can also act as RA potent regulators of cells proliferation, differentiation, and apoptosis, controlling osteoclasts, chondrocytes, and fibroblasts as well as immune cells chemotaxis to RA sites. Although much is already known, much more is still unknown, principally about the roles of organokines in the occurrence of RA extra-articular manifestations.  相似文献   

13.
石翛然 《广东化工》2014,(12):191-191
唇膏经微波消解,石墨炉原子吸收光谱法测定样品中铅、锰、铬、镉的含量。在优化的仪器工作条件下,质量浓度分别在32.0、8.0、8.0、8.0 mg/L范围内呈良好的线性关系,检出限分别为4.2、3.5、2.3、2.5μg/L,测得回收率在98%~103%之间,精密度分别为4.1%、3.6%、3.9%、2.7%。  相似文献   

14.
At the SAMRO AG plant in Burgdorf, Switzerland, the Ventafresh technology has been adopted for cleaning, disinfecting, and storage of potatoes. Ventafresh technologies include washing raw potatoes with ozone-containing water, then treatment with UV radiation in a specially designed “disinfection tunnel”. Ozone wash water disinfects the potatoes while field detritus is removed. UV radiation continues the disinfection and simultaneously destroys remaining ozone. After being processed in the Ventafresh tunnel, cleansed and disinfected potatoes are stored in a clean warehouse at high humidity in an atmosphere containing a lower concentration of ozone. When ready for marketing, the stored potatoes are washed with ozone/water, dried and graded, then washed in another bath with ultrasound and UV radiation, washed again in ozone/water, passed through a tunnel while being exposed to UV radiation (185 and 254 nm), passed through a bath of electrolyzed water, through another UV tunnel, packaged in a nitrogen?+?CO2 atmosphere, and distributed. The process is applicable to all root vegetables, plus root celery and asparagus, and also to certain fruits (apples, pears, kiwis, tomatoes, and Sharon fruits).  相似文献   

15.
健康产业发展潜力巨大,其中,医药、医疗和保健行业占有重要地位,但其面临医药资源利用率低、生产工艺污染严重、高端产品依赖进口、质量标准体系不完善等制约因素。将膜分离技术应用于医药、医疗和保健行业,解决发展面临的诸多问题,对于推进我国健康产业发展将发挥重要作用。鉴于国内外尚无针对膜技术应用于健康产业进展的相关文献报道,本文针对面向健康产业应用的膜技术及膜材料进展进行了综述,探讨了健康产业应用对膜材料提出的要求及标准,重点研究了微滤、超滤、反渗透、纳滤、膜生物反应器、渗透汽化、气体分离、人工脏器等膜材料现状,分析了制约其发展的关键问题并提出相关建议,以期为相关部门及行业人员提供参考。  相似文献   

16.
The degree of soil mining by agricultural production in Southern Mali is assessed by calculating nutrient balances: differences between the amount of plant nutrients exported from the cultivated fields, and those added to the fields. Export processes include extraction by crops, losses due to leaching, to erosion, and to volatilization and denitrification. Inputs include applications of fertilizer and manure, restitution of crop residues, nitrogen fixation, atmospheric deposition of nutrients in rain and dust, and enrichment by weathering of soil minerals. Nutrient balances are calculated for N, P, K, Ca, and Mg. Both pessimistic and optimistic estimates are given.The resulting figures indicate, even when the most optimistic estimates are used, large deficits for nitrogen, potassium and magnesium. For the region as a whole, the calculated deficits are -25 kg N/ha,-20 kg K/ha, and -5 kg Mg/ha. Further, acidification is to be expected, in particular in areas where cotton is grown. The deficits are caused by traditional cereal crops, but also by cotton and especially by groundnut. The latter two crops are fertilized, but insufficiently. It is important to note, that the negative figures are not automatic recommendations for application of a specific amount of additional fertilizer. For phosphorus and calcium the balance of the region as a whole appears to be about in equilibrium, but locally large variations may occur.Erosion and denitrification are important causes of nutrient loss, accounting respectively for 17 and 22% of total nitrogen exports. Atmospheric deposition and weathering of minerals in the soil are still important nutrient inputs that contribute as much as nutrients as organic and mineral fertilizer combined. Nutrient depletion is very large in comparison to the amount of fertilizer applied. Drastic options, such as doubling the application of fertilizer or manure, or halving erosion losses, even if feasible, would still not be enough to make up for the calculated deficits.The annual value of withdrawn nutrients, if related to prices of fertilizers, varies between 10,000 and 15,000 FCFA/ha (40-60 US $/ha). Since the estimated average gross margin from farming in this area is 34,000 FCFA/ha (123 US $/ha), soil mining appears to provide an amount equal to 40% of farmers' total income from agricultural activities.  相似文献   

17.
Adults and larvae of the thrips Callococcithrips fuscipennis (Moulton) (Thysanoptera: Tubulifera: Phlaeothripidae) live in the sticky wax masses of adult females of the felt scale insect Callococcus acaciae (Maskell) (Sternorrhyncha: Coccoidea: Eriococcidae). The scale is sessile and feeds on Kunzea shrubs (Myrtales: Myrtaceae). If stressed, the thrips produce droplets of secretions. The mixture contains pentadecane, tridecane, two monoterpenoids, hexadecyl butanoate, and smaller amounts of 15 other esters of long-chain unbranched alcohols identified as acetates, butanoates, hexanoates, and octanoates. The monoterpenoids are dolichodial, an iridoid, and an unknown substance with a mass spectrum very similar to that of anisomorphal and peruphasmal, diastereomers of dolichodial, but with a different retention time. Iridoids, butanoates, hexanoates, and octanoates have not been previously identified in Thysanoptera.  相似文献   

18.
Laccases (Lac) and tyrosinases (TYR) are mild oxidants with a great potential in research and industry. In this work, we review recent advances in their use in organic synthesis. We summarize recent examples of Lac-catalyzed oxidation, homocoupling and heterocoupling, and TYR-catalyzed ortho-hydroxylation of phenols. We highlight the combination of Lac and TYR with other enzymes or chemical catalysts. We also point out the biological and pharmaceutical potential of the products, such as dimers of piceid, lignols, isorhamnetin, rutin, caffeic acid, 4-hydroxychalcones, thiols, hybrid antibiotics, benzimidazoles, benzothiazoles, pyrimidine derivatives, hydroxytyrosols, alkylcatechols, halocatechols, or dihydrocaffeoyl esters, etc. These products include radical scavengers; antibacterial, antiviral, and antitumor compounds; and building blocks for bioactive compounds and drugs. We summarize the available enzyme sources and discuss the scalability of their use in organic synthesis. In conclusion, we assume that the intensive use of laccases and tyrosinases in organic synthesis will yield new bioactive compounds and, in the long-term, reduce the environmental impact of industrial organic chemistry.  相似文献   

19.
木质素是一种天然生物质资源,来源广泛,成本低廉。近年来,利用纳米技术将木质素制备成木质素功能化纳米颗粒极大推动了木质素的利用,同时显著解决了传统材料无法解决的突出问题。详细介绍了木质素功能化纳米颗粒的自组装法、机械法、聚合组装法、冻干炭化法等制备方法及其在催化剂、助剂、吸附剂、紫外防护和抗氧化、抗菌、载体材料、聚集诱导发光材料等领域的应用研究,展望了木质素纳米颗粒的应用前景。指出实现木质素纳米颗粒的可控制备、功能化修饰,将有利于推动木质素功能化纳米颗粒在环保、能源、催化和生物医学等领域的进一步应用。  相似文献   

20.
钟志光  陈强  张海峰  方永康  张震坤 《化学试剂》2007,29(4):223-225,234
采用DUO-ICP-AES同时测定精对苯二甲酸中钴、铬、铁、锰、钼、镍、钛,并对仪器的分析线选择、背景校正、入射功率、雾化器压力、辅助气流量、冷却气流量、蠕动泵转速的影响及共存元素的干扰、硝酸铯灰化助剂等因素进行了详细的研究。方法的检测限:钴0.0097 mg/L;铬0.0021 mg/L;铁0.0078 mg/L;锰0.0012 mg/L;钼0.0027 mg/L;镍0.016 mg/L;钛0.0027 mg/L,回收率和精密度分别为93.0%~99.5%和0.37%~3.2%。该方法快速简便,具有良好的精密度和准确度,适用于进出口精对苯二甲酸的日常检验。  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号