排序方式: 共有73条查询结果,搜索用时 15 毫秒
51.
Hepatic-targeting microcapsules construction by self-assembly of bioactive galactose-branched polyelectrolyte for controlled drug release system 总被引:3,自引:0,他引:3
We describe the construction of hepatic-targeting microcapsules by self-assembly of chemo-enzymatic synthesized poly(vinyl galactose ester-co-methacryloxyethyl trimethylammonium chloride) (PGEDMC) containing galactose branches, which can be specifically recognized by membrane bound galactose receptors (ASGPR), for acyclovir (ACV) controlled release system. Alternate deposition of PGEDMC and poly(sodium 4-styrenesulfonate) (PSS) was carried out on ACV microcrystals. It was revealed that the drug release rate decreases with the increase of coated layer number and a microcapsule-drying treatment would enhance the sustained release effect probably because of a multilayer shrink and tightness during the process. The complete release of ACV yielded a hollow PGEDMC/PSS multilayered network with favorable integrity and nano-thickness by TEM and SEM. The potential targetability of the system was proved in vitro by PNA lectin recognition. Lectin hardly adsorbed on the film where the outmost layer was a polyanion or a polycation without galactose component. Whilst the galactose-containing layer (PGEDMC) was the outmost layer, a significant lectin combination was observed. This technique could provide a promising way to encapsulate and deliver various target substances in biological and pharmaceutical applications. 相似文献
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高效液相色谱荧光检测法测定食品中的特丁基对苯二酚 总被引:1,自引:0,他引:1
1引言特丁基对苯二酚(TBHQ)是一种油溶性抗氧化剂,广泛用于食用油脂,能阻止或延迟油脂氧化变质,目前已在美国等20多个国家使用。因其具有一定的急性毒性和慢性致癌作用,各国对TBHQ的使用都有严格的限量规定,而在日本TBHQ尚未批准作为油脂抗氧化剂,并以此作为一种技术壁垒手段,要求方法检出限值达到1mg/kg。我国对油脂及其制品中抗氧化剂TBHQ的测定有薄层法、比色法、气相色谱法和高效液相色谱法等,但这些方法检出限值均不足以适应油脂制品输日新形势的需要,也有报道采用GC/MS测定TBHQ检出限可在1mg/kg以下,但方法样品前处理复杂,… 相似文献
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WEI Chun-Xia CHEN Jian-Xin ZHANG Zhi-Chun LAN Ting-Yan HUANG Yuan-Biao LI Zhong-Shui ZHANG Wen-Jie 《结构化学》2006,25(9)
A new molybdenum phosphate [Zn(Mov6P4O31H10)2(C4H14N3)2]·2C4H13N3·8H2O 1 (C4H13N3 = diethylenetriamine) has been synthesized under hydrothermal condition. Single-crystal X-ray diffraction reveals that compound 1 crystallizes in the monoclinic, space group P21/n, a =13.1679(3), b = 22.1240(6), c = 13.6146(3) (A), β = 103.4847(7)°, V = 3856.95(16) (A)3,C16H90N12O70P8ZnMo12, Mr = 3035.41, Z = 2, Dc = 2.614 g/cm3, μ = 2.483 mm-1, F(000) = 2968, S = 1.014, the final R = 0.0196 and wR = 0.0506 for 7486 observed reflections (I > 2σ(Ⅰ)). Compound 1 consists of two identical rings of six edge-sharing MoO6 octahedra interconnected by one ZnO6 octahedron, whereas the PO4 tetrahedra which share their apices with the MoO6 octahedra are only located on one side of each Mo6 ring. The 2-charge of polyanion [Zn(Mov6P4O31H10)2]2- unit is compensated in the crystal by two mono-protonated diethylenetriamines (C4H14N3)+. By hydrogen bonding interactions the polyanion of compound 1 is interconnected to form pseudo three dimensional molybdophosphate. Other characterizations by elemental analyses, IR spectrum and fluorescent spectrum are also described. 相似文献
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基于经典结晶理论讨论了非晶合金的晶化动力学因素和晶化热力学因素对玻璃形成能力(GFA)的影响.分析表明,合金的等温转变(TTT)曲线“鼻尖”温度Tn对应的黏度与晶化阻力因子成正比;重新加热时晶化开始温度Tx对应的黏度与晶化驱动力因子成反比.由此得到了新的GFA参数ω0=(Tg-T0)/(Tx-T0)-(Tg-T0)/(Tn-T0),其中Tg为玻璃转变温度,T0为理想玻璃转变温度.统计结果显示,ω0与临界冷却速率具有较高的相关性,R2高达09626.进一步分析表明:新提出的ω0参数可以合理地解释过冷熔体的黏度、脆性、液相稳定性、热稳定性以及Trg、ΔTx、γ、γm、ΔTrg、α、β、δ和φ等参数与GFA的关系.
关键词:
块体非晶合金
黏度
脆性
玻璃形成能力 相似文献
56.
Na Gao Zhi-Chun Shang Pei Yu Jie Luo Kai-Li Jian Ling-Yi Kong Ming-Hua Yang 《中国化学快报》2017,28(6):1194-1199
One new indoloditerpene,6,7-dehydropaxilline(1),one new indole-diketopiperazine,spirotryprostatin F(2),and one new 13-membered macrolide,N-demethylmelearoride A(3),as well as 8 known alkaloids(4-11),were isolated from the solid cultures of the endophytic fungus,Penicillium brefeidianum.The structures and absolute configurations of compounds 1-3 were elucidated by comprehensive spectroscopic analysis and the circular dichroism(CD) exciton chirality method.All the metablites were evaluated for their cytotoxic activites against three human tumor cell lines.Compound 2 exhibited cytotoxicities against HepG2 and MDA-MB-231 cells with IC_(50) values of 14.1 μmol/L and 35.5μmol/L,respectively.Compound 3 showed moderate activity against HepG2 cells with IC_(50) values of 36.6 μmol/L. 相似文献
57.
In this paper, a modified shear-lag model is developed to calculate the surface crack density in thermal barrier coatings(TBCs). The mechanical properties of TBCs are also measured to quantitatively assess their surface crack density. Acoustic emission(AE) and digital image correlation methods are applied to monitor the surface cracking in TBCs under tensile loading. The results show that the calculated surface crack density from the modified model is in agreement with that obtained from experiments. The surface cracking process of TBCs can be discriminated by their AE characteristics and strain evolution. Based on the correlation of energy released from cracking and its corresponding AE signals, a linear relationship is built up between the surface crack density and AE parameters, with the slope being dependent on the mechanical properties of TBCs. 相似文献
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Eighteen novel ω-(5-Aryl-1,3.4-oxadiazol-2-thio)-ω-(1-H-1,2,4-triazol-1-yl)acetophenones ( 4a-4i ) and ω-(5-Aryl-1,3,4-oxadiazol-2-thioacetoxyl)-ω-(1-H-1,2,4-triazol-1-yl)acetophenones ( 5a-5i ) were synthesized. All the compounds synthesized were confirmed by elemental analyses and spectral data. The biological activity of representative compounds was evaluated. 相似文献
60.
Bioactive galactose-branched polyelectrolyte multilayers and microcapsules: self-assembly, characterization, and biospecific lectin adsorption 总被引:1,自引:0,他引:1
Zhang F Wu Q Chen ZC Li X Jiang XM Lin XF 《Langmuir : the ACS journal of surfaces and colloids》2006,22(20):8458-8464
We describe the fabrication of multilayers and microcapsules with biologically designed targeting activity using chemoenzymatic synthesized carbohydrate-branched polyelectrolytes. A novel cationic d-galactose-branched copolymer [poly(vinyl galactose ester-co-methacryloxyethyl trimethylammonium chloride), PGEDMC] is alternated with poly(styrene sulfonate) (PSS) to form thin multifilms by the layer-by-layer (LbL) technique on such different solid surfaces as quartz slides, poly(ethylene terephthalate) (PET) films, silicon wafers, and polystyrene (PS) microparticles. The experimental protocols were first optimized on flat, smooth silica substrates using UV-vis, contact angle, and atomic force microscopy (AFM) measurements. The film properties of PGEDMC/PSS multilayers are modified by varying polyelectrolyte concentration, ionic strength, and counteranion types. Hollow capsules were formed after the removal of colloidal templates; transmission (TEM) and scanning (SEM) electron microscopy were used to verify the LbL process integrity. PGEDMC/PSS planar films and capsules carrying beta-galactose as recognition signals have specific recognition abilities with peanut agglutinin (PNA) lectin rather than concanavalin A (Con A) lectin observed by fluorescence spectroscopy. 相似文献