共查询到20条相似文献,搜索用时 62 毫秒
1.
恶性肿瘤由于其易转移、复发等特点,已经严重危害到人类的生命健康.近年来,研究人员设计了大量纳米药物载体,将抗肿瘤药物安全有效地运载到肿瘤,有效地提高了药效并降低了毒副作用.金属有机框架材料(metal-organic frameworks,MOFs)是一类有序、多孔的晶态材料,具有比表面积大、结构可设计性强、易生物降解等独特优势,已经被广泛应用于气体吸附与分离、催化、药物传递、生物大分子固载以及肿瘤治疗等方面.目前,基于MOFs的生物医用研究主要集中在MOF材料的可控合成,表面修饰,基于MOF独特理化性质发展的多模式成像技术以及肿瘤靶向的药物运载技术等几个方面.主要介绍了基于MOFs构建的生物功能化材料在肿瘤治疗中的应用,并对其在生物医学领域的应用进行了展望. 相似文献
2.
3.
4.
5.
羟基磷灰石(HA)是人体和动物骨骼的主要无机矿物成分。近年来,因HA具有特殊的表面特性和理化性能,良好的生物相容性、生物活性和骨传导作用,制备各种形态的HA材料成为从事生物、医学和材料的科研人员的研究重点。本文首先介绍了HA微球的制备方法,重点讨论了以聚合物为软模板以及用各种球形材料作为硬模板合成HA微球的制备方法,列出了不同方法制备HA微球的直径、孔径、比表面等各种性能参数。由于HA微球具有比表面积大、流动性好、质量轻、强度大,注射性能好,团聚能力低等HA块材不具有的特点,其在载体、骨修复材料、环境保护和色谱分离上有广泛的应用。针对HA微球在应用过程中遇到的问题,可采用表面改性或包覆、掺杂和将HA分散在其他基体中等措施对HA微球进行功能化修饰。HA 微球在控释载体、蛋白质分离以及细胞支架等方面具有极大的应用前景。 相似文献
6.
碳化硅(SiC)材料具有耐高温、 耐酸碱腐蚀和高机械强度等优异性能, 因此, 许多研究者都致力于制备优良的SiC材料以取代传统材料用作苛刻条件下催化剂的载体材料[1~4]. 研究结果表明, 具有高比表面积和空心核结构的载体材料可以负载更多的异质催化剂, 从而提高催化剂的催化性能. 因此, 制备同时具有高比表面积和空心核结构的SiC材料具有重要的应用价值. 传统的碳热还原反应、 自蔓延高温合成、 聚合物热分解等方法都不适合制备具有独特结构形貌的SiC材料[5~8]. 近年来, Ledoux等[1~4, 9]采用形状记忆合成(Shape memory synthesis)方法将不同形貌的固相碳材料与气相SiO蒸气反应, 成功地制备了不同形状的SiC材料, 比表面积在20~100 m2/g之间. Vix-Guterl等[10- 11]采用反应复制技术(Reactive replica technique)从C/SiO2材料制备了微米级的管状SiC材料. 另外, Tang等[12]采用水热合成法得到了纳米级的SiC空心球, 但产率不高. 本文利用具有核壳结构的SiO2@PPy粒子在1 300 ℃进行碳热还原反应, 成功制备同时具有较高比表面积和空心核结构的SiC空心球材料. 相似文献
7.
8.
氧化物、盐类在氧化物载体表面的自发分散是一种广泛存在的现象,文献中已报导过大量氧化物和盐类在高比表面载体上分散的研究结果['-3]TIO。作为一种较新型的载体,与Y-AI。O。、硅胶等传统载体相比,有许多不同特性.活性组分在TIO。表面的分散状态及所得催化剂的性能已有不少报导['-'],但所用的TIOZ主要是较高比表面的锐钛矿型TIOZ(刘金红石型TIO。(r)和锐钛矿型TIOZ(a)的结构不同,它是高温生成相,比表面较小['].氧化物在金红石上的分散行为仍未见报导.我们制备了三种具有不同比表面的TIO水),系统地研… 相似文献
9.
10.
采用纳米浇铸法制备了高比表面积(345 m2/g)且孔径均一的有序介孔SiC材料(SiC-OM),以商用SiC(49 m2/g,SiC-C)材料为参比载体。采用等体积浸渍法分别制备了Ni/SiC-OM和Ni/SiC-C,并考察其在CH4-CO2重整反应中的催化性能。利用ICP、BET、XRD、H2-TPR、XPS、HRTEM、TG和Raman等手段对反应前后的两种催化剂进行表征。结果表明,在700℃、1.013×105 Pa和12 L/(h·g)的重整条件下,Ni/SiC-OM的平均积炭速率比Ni/SiC-C降低了一个数量级,这主要归因于强金属-载体相互作用和有序介孔骨架的"限域效应"作用。 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.
Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction
Laurent Gavara Thomas Boisse Jean-Pierre Hénichart Adam Daïch Philippe Gautret 《Tetrahedron》2010,66(38):7544-5571
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
13.
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
14.
Rebecca J. Burton Mandy L. CrowtherNeal J. Fazakerley Shaun M. FilleryBarry M. Hayter Jason G. KettleCaroline A. McMillan Paula PerkinsPeter Robins Peter M. SmithEmma J. Williams Gail L. Wrigley 《Tetrahedron letters》2013
The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines. 相似文献
15.
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
16.
N. A. Nedolya 《Chemistry of Heterocyclic Compounds》2008,44(10):1165-1219
The review contains a concise historical account and information on the most significant researches undertaken by the staff
at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences on the Chemistry
of Heterocyclic Compounds.
Dedicated to Academician of the Russian Academy of Sciences B. A. Trofimov on his 70th jubilee.
Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1443–1502, October, 2008. 相似文献
17.
Regiospecific and direct imidation of the methyl C(sp3)–H bond of thioanisoles is realized under mild and metal-free conditions with N-fluorobis(benzenesulfonyl)imide as an oxidant and nitrogen source. Proposed mechanism suggests that thionium ion intermediates and a Pummerer-type reaction are involved. The imidation has advantages such as high step-economy, excellent functionality tolerance, and regiospecificity, giving structurally diverse imidation products. 相似文献
18.
19.
《Tetrahedron》2014,70(21):3377-3384
The Rh(II)-catalyzed reaction of 2-carbonyl-substituted 2H-azirines with ethyl 2-cyano-2-diazoacetate or 2-diazo-3,3,3-trifluoropropionate provides an easy access to 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones. These compounds can be selectively prepared from the same starting material using temperature as the only varied parameter. The 2-azabuta-1,3-diene intermediate, a common precursor for both heterocyclic products, isomerizes into 2H-1,3-oxazine under kinetic control, while 1H-pyrrol-3(2H)-one is the sole product of the reaction at elevated temperatures. According to DFT-calculations a one-atom oxazine ring contraction involving ring-opening to a 2-azabuta-1,3-diene intermediate, followed by a 1,5- and 1,2-prototropic shift leads to the consecutive formation of imidoylketene and azomethine ylide, which then further undergo cyclization to the pyrrole derivative. 相似文献
20.
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