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1.
锂离子二次电池碳负极材料的改性   总被引:5,自引:1,他引:5  
吴宇平  万春荣 《电化学》1998,4(3):286-292
作为锂离子二次电池的碳负极材料,其改性方面的研究内容主要有:引入非金属元素,引入金属元素,处理表面及其它方面。纺入的非金属元素有硼,硅,氮,磷和硫。引入的金属元素有钾,铝,镓和钒,镍,钴,铜,铁等过渡金属元素。表面处理的方法包括氧化,形成表面层等。  相似文献   

2.
阿尔茨海默病(AD),俗称老年痴呆症,是一种老年神经退行性疾病,其病理特征为脑神经细胞间隙的老年斑(senile plaques,SP)、神经细胞内的神经纤维缠结(neurofibrillary tangles,NFTs)、神经元数量减少和颗粒空泡变性。尽管AD的发病机理十分复杂,但是淀粉样多肽(Aβ)、淀粉样前体蛋白(APP)、金属硫蛋白-3(MT3)及其所参与调节的金属离子内稳态平衡与AD的发生发展有着密切的联系。过渡金属离子如铜和锌,在人体正常的生理过程中发挥着重要的作用,而在阿尔茨海默病患者的大脑内,金属内稳态失衡可能是阿尔茨海默病的主要诱因之一。金属内稳态的失衡会影响淀粉样多肽的聚集以及活性氧物种(ROS)的产生,进而产生细胞毒性;而金属硫蛋白-3(MT3)参与调节大脑金属稳态平衡,具有解聚淀粉样多肽,降低神经细胞毒性的作用。本文综述了大脑过渡金属铜、锌、铁稳态平衡及其调控机制有关的研究进展。  相似文献   

3.
铜是人体中重要的微量金属元素之一,在多种生命活动中起着不可或缺的作用,包括电子传递、线粒体功能以及多种酶的活性。铜的缺乏或过量都会对人体产生严重、甚至是致命的危害,所以铜的摄取、胞内组装和代谢都需要严格的调控。铜的内稳态平衡的破坏可以导致贫血、威尔逊疾病和门克斯疾病,并严重影响大脑的功能。近年来的研究发现,肿瘤的生长、免疫系统的功能也与铜有着密不可分的联系。本文介绍铜在人体中的生物学功能、铜蛋白的作用以及铜的运输机制及储存机制,并对铜与相关疾病的关系进行讨论。  相似文献   

4.
用原子吸收光谱法测定了陕西汉中地区266例健康男女青少年头发中5种金属元素的含量。并进行了直线相关回分析。结果表明,青春期女性头发中的铜,锌、铁、钙,镁5种元素的含量皆明显高于同年龄段男性;Ca与Mg、Zn、Fe元素含量之间有不同程度的相关。  相似文献   

5.
为探讨婴儿体内铜、锌、钙、镁、铁和铅微量元素的含量及其与年龄、性别的关系,测定了1 152例湖南长沙地区1岁内婴儿指末梢全血中6种元素铜、锌、钙、镁、铁和铅的含量,对其结果进行了统计分析。结果表明,所测婴儿元素铁、锌缺乏最显著,其次是钙缺乏;铜、镁无明显失衡;血铅超标的水平较低;不同性别之间6种元素含量的差异无统计学意义。提示在长沙地区的孕婴保健中,应加强锌、钙与铁的合理补充。  相似文献   

6.
冠醚类化合物对碱金属,碱土金属元素离子具有选择性配位能力,这类化合物与过渡金属元素离子所形成的配合物,文献亦有报道,但对既有碱金属(碱土金属,NH_4~+)又含有过渡金属元素,双金属元素离子冠醚类配合物研究较少。本文用凝胶法培养出18-冠-6钡和硫氰酸铁的配合物单晶,用X射线衍射分析其晶体和分子结构。  相似文献   

7.
研究了负离子模式下锰、铁、钴、镍、铜和锌等常见过渡金属的微波等离子体炬(MPT)质谱特征,阐明了这些金属元素在MPT中形成阴离子的规律;初步得出饮用水中这些金属元素的最低检出限(LOD)均在约20μg/L量级,为实际检测这些金属元素奠定了基础.  相似文献   

8.
为了解沈阳市学龄前儿童体内矿物质钙、铁、锌、铜、镁的含量与年龄和性别的关系,探讨防治其缺乏的综合措施,利用BH 5100型原子吸收光谱仪对3483例学龄前儿童末梢血中铜、锌、钙、镁和铁元素进行了检测,采用SPSS 17.0软件进行统计分析。结果表明,该地区学龄前4个不同年龄组儿童末梢血锌、钙、铁、铜元素缺乏严重,分别占总样本的66.90%、39.76%、32.5%和26.87%;3~岁组末梢血中钙、铁、锌、镁含量与其它年龄组比较差异有统计学意义(P〈0.05),各元素在性别问差异无统计学意义(P〉0.05)。该地区学龄前儿童钙、铁、锌、铜失衡明显,应加强营养素的合理搭配及矿物质的补充,保证儿童的健康成长。  相似文献   

9.
自50年代初成功地合成了二茂铁并确定其结构以来,金属有机化学获得了迅速发展,尤其是铜铁金属有机化合物越来越多,测定其铜铁元素以确认化合物或判断水质污染情况都有很重要的意义。 铜铁金属有机化合物中的金属元素与碳键合无论为共价键或共振键或配位键都能被浓硫酸和浓硝酸的混酸加热消化,铜铁元素转变成易溶于水的盐,就能很方便地利用EDTA配位滴定测得铜铁元素的含量。1 试验方法1.1 铁有机化合物的分析1.1.1消化分解 准确称取试样(约含铁40mg)于消化瓶中,加入浓硫酸5ml及浓硝酸5ml,加热消化至冒白烟,消化液为透明黄绿色。冷却后用少许水冲洗瓶壁,加热煮沸片刻,冷却至室温,转移入100ml量瓶中,加水至标线,摇匀。  相似文献   

10.
过渡金属基材料成本相对较低,催化性能较为优异,是在全水分解领域最有希望替代贵金属基电催化剂的候选材料之一,但有限的活性位点、相对较差的电导率等因素限制了其广泛应用。非金属元素掺杂能够调节主体材料电子结构,优化吸附能,从而对过渡金属基电催化剂的活性与稳定性产生积极影响,缩减其与贵金属材料性能差距。本文总结了近年来非金属元素改性在过渡金属基电催化材料中的相关研究,系统综述了非金属元素掺杂的方法和不同非金属元素的掺杂效果,从物理化学性质的改变和电子结构的变化多角度分析了非金属元素改性对过渡金属基材料的影响,最后对非金属元素掺杂过渡金属基电催化剂的未来发展方向作出了展望。  相似文献   

11.
用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%.  相似文献   

12.
Different approaches for the synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives from simple amino acids have been investigated. A library of 33 precursors for the preparation of N-hydroxy pyrazinones was obtained in moderate to good yields.  相似文献   

13.
A general synthesis of previously unknown semicarbazone-based α-amidoalkylating reagents, 4-(tosylmethyl)semicarbazones, has been developed. The synthesis involved three-component condensation of semicarbazones of aliphatic or aromatic aldehydes with the same or other aldehydes and p-toluenesulfinic acid. The scope and limitations of this reaction were investigated. The compounds obtained were demonstrated to be an efficient α-(4-semicarbazono)alkylating agents. They were reacted with H- (sodium borohydride), O- (sodium methylate), S- (sodium phenylthiolate), N- (pyrrolidine, sodium succinimide), P- (trialkyl phosphites), and C-nucleophiles (sodium diethyl malonate) to give the corresponding products of the tosyl group substitution, 4-substituted semicarbazones, including analogues of nitrofurazone. Among the prepared compounds tested in vitro for antibacterial and antifungal activity, three nitrofuryl-containing semicarbazones exhibited high biological activities with minimum inhibitory concentration (MIC) values of 8–32 μg/mL.  相似文献   

14.
In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments.  相似文献   

15.
A small library of new chiral bidentate hydroxyalkyl-imidazolium salts 1 is conveniently synthesized on multi-gram scale from inexpensive and commercially available chiral pool amino acids. The corresponding carbenes, generated by deprotonation of imidazolium salts 1, in combination with palladium(II) chloride were tested in the Mizoroki–Heck coupling reaction. The most significant results in terms of yields and reactivities were achieved with low catalyst loading. The catalytic activities of these imidazolium salts were also investigated in the asymmetric addition of diethylzinc to benzaldehyde. The use of MgO nanoparticles as an additive in conjunction with these ligands played a crucial role in increasing the efficiency of these reactions.  相似文献   

16.
A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives.  相似文献   

17.
The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp3)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp2)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp2)?H and aliphatic 1,5- and 1,6-C(sp3)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp3)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp2)?H insertion.  相似文献   

18.
The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula.  相似文献   

19.
Siqi Li  Xingpeng Chen  Jiaxi Xu 《Tetrahedron》2018,74(14):1613-1620
Microwave-assisted copper-catalyzed ring expansions of three-membered heterocycles with α-diazo-β-dicarbonyl compounds were investigated. Thiiranes generated 3-acyl-5,6-dihydro-1,4-oxathiines in the presence of copper sulfate and trans-3-acyl-5,6-dihydro-1,4-oxathiines as stereospecific products for 1,2-disubstituted cis-thiiranes through an intramolecular SN2 process. Oxiranes gave rise to 2-acyl-5,6-dihydro-1,4-dioxines under the catalysis of copper hexafluoroacetylacetonate and cis-3-acyl-5,6-dihydro-1,4-dioxines as stereospecific products for 1,2-disubstituted cis-oxiranes via an intimate ion-pair mechanism. The current method provides a direct and simple strategy in efficient preparation of 3-acyl-5,6-dihydro-1,4-oxathiines and 2-acyl-5,6-dihydro-1,4-dioxines, important agents in medicinal and agricultural chemistry, from readily available thiiranes and oxiranes, respectively.  相似文献   

20.
KMnO4-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields.  相似文献   

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