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<正> 镉是对人体有害的元素,特别是它的污染物能在自然界中积蓄,而且可富集于食物链中,并可通过水—土壤—粮食、水—水生物等途径进入人体,而使人中毒,甚至死亡。痕量镉的测定已有很多报道,但大多数是采用原子吸收分光光度法测定,样品经萃取分离,灵敏度为2.5ppb,而对沉积物中痕量镉的测定方法则少见报道。我们采用双硫腙萃取分离与镉共存的其它元素,以普通直流极谱仪与XBD—1型旋转玻璃碳汞膜 相似文献
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C—H键作为有机化合物的基本单元,实现其直接的C—H键官能团化反应是简洁的合成方法.羧酸广泛存在于自然界,基于羧基的导向基团与离去基团双重角色所驱动的过渡金属催化羧酸邻位C—H键官能团化可控合成,不仅规避了C—H键活化过程中导向基团的额外引入与移除,也彰显了基于羧基“一石二鸟”策略的C—H键活化简洁性与脱羧绿色性.因此,基于“一石二鸟”策略的羧基无痕导向其邻位C—H键官能团化反应,能为可控定向合成提供新的策略和方法,在合成化学上具有显著意义.根据参与反应的偶联底物类型,分别介绍了基于“一石二鸟”策略的过渡金属催化羧酸邻位C—H键活化与含重键试剂、芳基化试剂及含杂原子试剂的反应,并对相关的一些反应机理进行了探讨. 相似文献
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Jin-Long YANG 《物理化学学报》2017,33(3):445-446
<正>六方金刚石(hexagonal diamond,HD),又称蓝丝黛尔石(Lonsdaleite)是自然界中神秘的物质。六方金刚石在自然界非常稀少,科学界普遍认为自然界中的六方金刚石是流星上的石墨坠入地球时形成的。流星撞击地球会产生了巨大的热量与压强,从而导致石墨发生相变形成金刚石。第一次发现六方金刚石是在美国亚利桑那州的巴林杰 相似文献
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对化学的挑战——分子铁磁体的设计 总被引:5,自引:0,他引:5
寻求常温下的分子铁磁体是自然界向化学家挑战的一个热点课题.本文介绍了迄今美、俄、法、日等国家在该领域已取得的最新成果及已采用的几种设计与合成途径,即有机方法、金属有机方法、金属—自由基方法和无机方法等.其中通过无机方法制得的铜锰交替链状配合物的铁磁相转变温度(T_c)达到30K,这是目前通过各种方法制得的T_c最高的分子铁磁体。 相似文献
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自然界是辩证发展的,人类对自然界的斗争——生产活动也是辩证发展的。我们厂氯化汞的生产过程就充满着辩证法。氯化汞是一种剧毒的白色粉末,致死量为0.2—0.4克。以前,我厂把它作为化学试剂,每年进行少量生产。但是,随着我国塑料工业蓬勃兴起,作为塑料工业的催化剂,对氯化汞的需求急剧增加。通过无产阶级文化大革命,同志们批判了“专家治厂”、“技术第一”的修正主义路线,坚持抓革命、促生产的正确方针,以毛主席的哲学思想为武器,充分发挥人的主观能动性,大搞技术革新、技术革命,实现了连续生产和半自动化操作,使我厂氯化汞产量不断提高,为发展塑料工业做出了应有的贡献。 相似文献
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绿色化学理念的基本内涵既有微观意义又有宏观意义与工程技术的意义。绿色化学及其绿色技术在社会生产与生活、传统化学工业改造与创新、资源合理充分利用与循环再生、绿色净化与监测、环境保护与开发等方面发挥重要作用。实施绿色化学及其绿色系统工程技术,使社会生产、生活绿色化,实现人类与环境友好对话,建设“环境友好”家园,营造“环境和谐”生活,是坚持可持续发展、科学发展核心战略的重要举措,是当今世界人类面临的重大挑战与机遇。 相似文献
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Prof. K. C. Nicolaou 《Angewandte Chemie (International ed. in English)》2014,53(35):9128-9140
The current state of affairs in the drug discovery and development process is briefly summarized and then ways to take advantage of the ever‐increasing fundamental knowledge and technical knowhow in chemistry and biology and related disciplines are discussed. The primary motivation of this Essay is to celebrate the great achievements of chemistry, biology, and medicine and to inform and inspire students and academics to enter the field of drug discovery and development while, at the same time, continue to advance the fundamentals of their disciplines. It is also meant to encourage and catalyze multidisciplinary partnerships between academia and industry as scientists attempt to merge their often complementary interests and expertise to achieve new improvements and breakthroughs in their respective fields, and the common goal of applying them to the discovery and invention of new and better medicines, especially in areas of unmet needs. 相似文献
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Semiconductor quantum dots and metal nanoparticles: syntheses,optical properties,and biological applications 总被引:1,自引:0,他引:1
Biju V Itoh T Anas A Sujith A Ishikawa M 《Analytical and bioanalytical chemistry》2008,391(7):2469-2495
We review the syntheses, optical properties, and biological applications of cadmium selenide (CdSe) and cadmium selenide–zinc
sulfide (CdSe–ZnS) quantum dots (QDs) and gold (Au) and silver (Ag) nanoparticles (NPs). Specifically, we selected the syntheses
of QDs and Au and Ag NPs in aqueous and organic phases, size- and shape-dependent photoluminescence (PL) of QDs and plasmon
of metal NPs, and their bioimaging applications. The PL properties of QDs are discussed with reference to their band gap structure
and various electronic transitions, relations of PL and photoactivated PL with surface defects, and blinking of single QDs.
Optical properties of Ag and Au NPs are discussed with reference to their size- and shape-dependent surface plasmon bands,
electron dynamics and relaxation, and surface-enhanced Raman scattering (SERS). The bioimaging applications are discussed
with reference to in vitro and in vivo imaging of live cells, and in vivo imaging of cancers, tumor vasculature, and lymph
nodes. Other aspects of the review are in vivo deep tissue imaging, multiphoton excitation, NIR fluorescence and SERS imaging,
and toxic effects of NPs and their clearance from the body.
Figure Semiconductor quantum dots and metal nanoparticles have extensive applications, e.g., in vitro and in vivo bioimaging
Tamitake Itoh and Abdulaziz Anas contributed equally to this article. 相似文献
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本研究采集了印度洋热液区贻贝生物及其栖息沉积物样品,分析了生物体及沉积物中常见微量元素及稀土元素的含量与分布特征,研究了生物体与沉积物金属元素的相关性,以及稀土元素的生态化学特征等.结果表明:印度洋热液区沉积物中常见微量金属主要为Fe(96.62 mg/kg)、Mn(1.143 mg/kg)和Zn(322.6 μg/kg),微量元素归一化计算得Fe含量比值高达98.15%,可获悉该热液区沉积物主要为铁矿类物质.深海贻贝中微量元素及稀土元素的分布趋势与深海沉积物中元素分布存在较好的相关性,相关性系数分别为0.991与0.996,近海贻贝中金属元素的含量及分布与深海贻贝存在差异性.深海沉积物与贻贝中轻重稀土元素均呈现分馏现象,且贻贝中富集轻稀土比较显著;从稀土配分模式可知,沉积物与贻贝中的Eu与Gd均呈现异常现象,深海沉积物和深海贻贝中Eu异常现象较为显著.深海沉积物、贻贝及近海贻贝中δEu分别为9.50、10.68和0.23,而δCe分别为2.21、2.71和4.38,表明近海贻贝中稀土元素富集来源与深海贻贝存在差异性,深海沉积物与深海贻贝稀土元素具有同源性. 相似文献
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《Trends in analytical chemistry : TRAC》1986,5(4):97-102
The scope of polarography and voltammetry in analyzing azo dyes, anthraquinone-, polycondensed aromatic and vat dyes, di- and triarylcarbonium and heterocyclic dyes, nitro-, nitroso dyes and nitro intermediates, intermediates such as sulphonation products of 2-naphthol, diazonium salts and diazonium compounds is outlined. In view of much tougher future toxicological and environmental constraints and new outlets for dyes in modern high technology industries, polarography and voltammetry may find new and wider application and recognition. 相似文献
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剌梨利康饮对汞中毒大鼠汞铜锌含量的影响 总被引:1,自引:1,他引:0
用高汞水喂养大鼠8周,复制出慢性汞中毒模型,再分别自由饮用利康饮饮料和腹腔注射二巯基丙磺酸钠3周,探讨剌梨利康饮和二巯基丙磺酸钠对慢性汞中毒大鼠体内汞、铜、锌含量的影响。结果显示:慢性汞中毒引起血清、肝、脑和肾中汞含量升高的同时,引起血清、脑和肾中铜、锌含量及肝中锌含量降低;利康饮可降低血清和肾中汞含量,并可提高血清、脑和肾中铜、锌含量及肝含量;二巯基丙磺酸钠虽可降低血清、肝和肾中汞含量,升高血清 相似文献
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Rupak Raja Syed Dilshad Alam Vikas Srisath Arvind Kumar Jain Zeid A. ALOthman Abdallah A. A. Mohammed Mohammad Ataul Islam Tahir Bhatt Imran Ali 《Journal of separation science》2022,45(4):804-811
A comparative study of chiral separation of pantoprazole and rabeprazole is carried out using supercritical fluid chromatography and high-performance liquid chromatography. The columns used were Chiralpak IA and Chiralpak IE. The best mobile phase in supercritical fluid chromatography was carbon dioxide-0.2% triethylamine in methanol (60:40) and 0.1% triethylamine in n-hexane-ethanol (50:50) in high-performance liquid chromatography. For supercritical fluid chromatography, values of the retention factor of pantoprazole enantiomers were 3.97 and 4.88. These values for rabeprazole enantiomers were 6.10 and 7.52. The values of separation and resolution factor for pantoprazole and rabeprazole were 1.23 and 1.23 and 2.20 and 3.36, respectively. Similarly, for high-performance liquid chromatography, the values of retention factor for enantiomers of pantoprazole were 4.02 and 7.32. These values for rabeprazole enantiomers were 5.32 and 7.88, respectively. The values of separation and resolution factor for pantoprazole and rabeprazole were 1.82 and 1.48 and 9.22 and 6.58, respectively. A comparison was carried out, which confirmed supercritical fluid chromatography as the best method due to its fastness, eco-friendly, and inexpensiveness. The reported methods are effective, efficient, and reproducible and may be used to separate and identify pantoprazole and rabeprazole in any unknown samples. 相似文献
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Mutual physiological genetic mechanism of plant high water use efficiency and nutrition use efficiency 总被引:1,自引:0,他引:1
Cao HX Zhang ZB Xu P Chu LY Shao HB Lu ZH Liu JH 《Colloids and surfaces. B, Biointerfaces》2007,57(1):1-7
Water deficiency and lower fertilizer utilization efficiency are major constraints of productivity and yield stability. Improvements of crop water use efficiency (WUE) and nutrient use efficiency (NUE) is becoming an important objective in crop breeding. With the introduction of new physiological and biological approaches, we can better understand the mutual genetics mechanism of high use efficiency of water and nutrient. Much work has been done in past decades mainly including the interactions between different fertilizers and water influences on root characteristics and crop growth. Fertilizer quantity and form were regulated in order to improve crop WUE. The crop WUE and NUE shared the same increment tendency during evolution process; some genes associated with WUE and NUE have been precisely located and marked on the same chromosomes, some genes related to WUE and NUE have been cloned and transferred into wheat and rice and other plants, they can enhance water and nutrient use efficiency. The proteins transporting nutrient and water were identified such as some water channel proteins. The advance on the mechanism of higher water and nutrient use efficiency in crop was reviewed in this article, and it could provide some useful information for further research on WUE and NUE in crop. 相似文献
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蛋白质的磷酸化和糖基化作为研究最广泛的两种翻译后修饰(PTMs),在疾病的早期无创诊断、预后和治疗评估中表现出越来越大的潜力。蛋白质的异常磷酸化和糖基化经常被用于临床蛋白质组学研究和疾病相关生物标志物的发现。目前已有多种材料被开发用于磷酸化肽和糖肽的富集研究,其中,智能响应材料由于具有独特的响应特性,已被陆续报道用于磷酸化肽和糖肽的富集。智能响应材料可对外界刺激做出响应,发生结构和性质上的变化,将光、电、热、机械等信号转化为生物化学信号。响应分子是决定智能响应材料响应特性的先决条件,它们在不同刺激条件下(如温度、pH、光、机械应力、电磁场等)的可逆异构化将导致材料的宏观物理和化学性质的动态变化。与传统材料相比,智能响应材料可以可逆地“打开”和“关闭”,具有更好的可调控性。由于引起智能材料响应的刺激信号对其性能具有重要的影响,综述根据施加的刺激种类对智能响应材料进行分类,具体分为外源性响应材料和内源性响应材料,且分别总结了外源性响应材料、内源性响应材料以及内外源共同响应材料在磷酸化肽和糖肽富集方面的工作。此外,综述对智能响应材料在磷酸化肽和糖肽富集方面的发展前景进行了展望,并且提出了智能响应材料在其他蛋白质翻译后修饰方面的应用中存在的挑战。 相似文献