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《Tetrahedron》2014,70(51):9695-9701
Seven new prenylated phenols, vaccinols A–G (1–7), and one new naphthalene derivative, vaccinal A (8), together with five known phenol derivatives (9–13) were isolated from Pestalotiopsis vaccinii (cgmcc3.9199) endogenous with the mangrove plant Kandelia candel (L.) Druce (Rhizophoraceae). The new structures were established on the basis of spectroscopic analysis, optical rotation, CD spectra, quantum ECD calculations. Furthermore, the absolute configuration of compound 1 was unambiguously elucidated by single-crystal X-ray diffraction analysis using the Flack parameter. Most new compounds were tested for their antiviral (EV71), cytotoxic, antituberculosis, and anti-inflammatory effects. Among them, compound 8 exhibited in vitro anti-enterovirus 71 (EV71) with IC50 value of 19.2 μM. In addition, 8 showed potent COX-2 inhibitory activity with IC50 value of 1.8 μM. 相似文献
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有限元离散一类速度追踪问题后得到具有鞍点结构的线性系统,针对该鞍点系统,本文提出了一种新的分裂迭代技术.证明了新的分裂迭代方法的无条件收敛性,详细分析了新的分裂预条件子对应的预处理矩阵的谱性质.数值结果验证了对于大范围的网格参数和正则参数,新的分裂预条件子在求解有限元离散速度追踪问题得到的鞍点系统时的可行性和有效性. 相似文献
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采用种子生长法制备金纳米棒(AuNRs)以构建光学传感器,用于 Fe3+和 Cu2+的高选择性快速可视化检测。在酸性环境中,Fe3+和 Cu2+通过与 KI溶液反应,将 I-氧化成 I2。I2刻蚀 AuNRs,导致其纵向表面等离子体共振(LSPR)吸收峰蓝移,从而实现对Fe3+和Cu2+的检测。结果表明,反应温度为50℃时,添加0.8 mL 0.1 mol·L-1 HCl、2 mL AuNRs生长液和20 mmol·L-1 KI溶液,与 2 mL 500 μmol·L-1 Fe3+或 30 μmol·L-1 Cu2+反应 25或 90 min,可将 AuNRs刻蚀至 LSPR 吸收峰消失。该方法对 Fe3+和 Cu2+检测具有高选择性和准确性,对于 Fe3+、Cu2+共存体系的检测,可通过加入适量 F-与 Fe3+生成配合物[FeF6]3-完成对 Fe3+的化学掩蔽,消除Fe3+的干扰,实现共存体系中Cu2+的准确检测。 相似文献
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本文研究了三角代数的自同构.利用三角代数的基本概念及自同构定义,得到三角代数的自同构形式,并刻画了其内自同构的具体形式. 相似文献
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Two new families of finite binary sequences are constructed using multiplicative inverse. The sequences are shown to have strong pseudorandom properties by using some estimates of certain exponential sums over finite fields. The constructions can be implemented fast since multiplicative inverse over finite fields can be computed in polynomial time. 相似文献
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卢国富 《数学年刊A辑(中文版)》2007,(4)
研究主部为热传导算子的拟线性抛物型方程Cauchy问题:u_t=u_(xx) (u~n)_x,(x,t)∈S=R×(0,∞),u(x,0)=δ(x),x∈■在一维情形下源型解的存在性,唯一性,不存在性,解的渐近性和相似源型解等问题.在研究过程中,找到了一个n的临界值,即n_0=3.当0≤n相似文献
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Chong-Guang Cao Zhong-Peng Yang Xian Zhang 《Journal of Applied Mathematics and Computing》2002,10(1-2):101-109
We extend two inequalities involving Hadamard products of positive definite Hermitian matrices to positive semi-definite Hermitian matrices. Simultaneously, we also show the sufficient conditions for equalities to hold. Moreover, some other matrix inequalities are also obtained. Our results and methods are different from those which are obtained by S. Liu in [J. Math. Anal. Appl. 243:458–463(2000)] and B.-Y. Wang et al. in [Lin. Alg. Appl. 302–303: 163–172(1999)]. 相似文献
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A novel electrochemiluminescence (ECL) “sandwich” biosensor has been developed to detect cocaine. The sandwich biosensor was
fabricated on the basis of the fact that a single aptamer could be split into two fragments and the two dissociated parts
could form a folded, associated complex in the presence of targets. One of these (capture probe), which had hexane–thiol at
its 5′-terminus, was immobilized on a gold electrode via thiol–gold binding. The other one (detection probe) was labeled with
the ECL reagent tris(2,2′-bipyridyl)ruthenium(II)-doped silica nanoparticles (RuSiNPs) at its 3′-terminus. Owing to the weak
interaction between the two fragments, the sensor exhibited a low ECL signal in the absence of cocaine. After the target cocaine
had been added to the solution, it induced association of the two fragments and stabilized the associated complexes, leading
to immobilization of RuSiNPs on the electrode surface, and the ECL detected on the electrode surface was enhanced. The enhanced
ECL intensity was directly proportional to the logarithm of the cocaine concentration in the range from 1.0 × 10−9 to1.0 × 10−11 mol/L, with a detection limit of 3.7 × 10−12 mol/L. The biosensor was applied to detect trace amounts of cocaine on banknotes with satisfactory results. 相似文献
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《Radiation Physics and Chemistry》2007,76(8-9):1308-1311
In this work, blends of a difunctional epoxy monomer and a thermoplastic toughening agent are E-beam irradiated at two different dose rates and two different total absorbed doses. The influence of the processing conditions on the thermal properties and on the morphology of the obtained matrices has been investigated. In particular, it is shown how the increase of the dose rate causes an increase of the temperature during irradiation, thus inducing a simultaneous thermal and radiation curing. On the contrary, at low-dose rate the system mainly undergoes to radiation curing, thus making the cured material very sensible to a post-irradiation thermal treatment with a significant improvement of the thermal properties. 相似文献