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61.
本文针对第二类端点奇异Fredholm积分方程构造基于分数阶Taylor展开的退化核方法,设计了两种计算格式,一是在全区间上使用分数阶Taylor展开式近似核函数,二是在包含奇点的小区间上采用分数阶插值,在剩余区间上采用分段二次多项式插值逼近核函数.讨论了两种退化核方法收敛的条件,并给出了混合插值法的收敛阶估计.数值算例表明对于非光滑核函数分数阶退化核方法有着良好的计算效果,且混合二次插值法比全区间上的分数阶退化核方法有着更广泛的适用范围. 相似文献
62.
Acta Mathematicae Applicatae Sinica, English Series - In this paper, we investigate standing waves in discrete nonlinear Schrödinger equations with nonperiodic bounded potentials. By using the... 相似文献
63.
Empirical likelihood inference for parametric and nonparametric parts in functional coefficient ARCH-M models is investigated in this paper. Firstly, the kernel smoothing technique is used to estimate coefficient function δ(x). In this way we obtain an estimated function with parameter β.Secondly, the empirical likelihood method is developed to estimate the parameter β. An estimated empirical log-likelohood ratio is proved to be asymptotically standard chi-squred, and the maximum empirical likelihood estimation(MELE) for β is shown to be asymptotically normal. Finally, based on the MELE of β, the empirical likelihood approach is again applied to reestimate the nonparametric part δ(x). The empirical log-likelohood ratio for δ(x) is proved to be also asymptotically standard chi-squred. Simulation study shows that the proposed method works better than the normal approximation method in terms of average areas of confidence regions for β, and the empirical likelihood confidence belt for δ(x) performs well. 相似文献
64.
Deliang Kong Lihua Guo Meng Tian Shumiao Zhang Zhenzhen Tian Huayun Yang Ye Tian Zhe Liu 《应用有机金属化学》2019,33(1)
Fifteen organometallic Ir(III) half‐sandwich complexes ( 1A – 5C ) having the general formula [(η5‐Cpx)Ir(N^N)Cl]PF6 (Cpx = Cp*, tetramethyl(phenyl)cyclopentadienyl (Cpxph) or tetramethyl(biphenyl)cyclopentadienyl (Cpxbiph); N^N = diamine) have been synthesized and characterized. The molecular structure of 1A was determined using single‐crystal X‐ray diffraction analysis. The hydrolysis of 1A – 5C was monitored using UV–visible spectra. Complexes 3A – 3C showed catalytic activity for the oxidation of NADH to NAD+, where 3C showed the highest turnover number of 29.9 within 450 min. Cytotoxicity examination by MTT assay was carried out against two human cancer cell lines (HeLa and A549) after 24 or 48 h drug treatment. The complexes showed high potency, where the most potent complex ( 3C ; IC50 = 3.4 μM) was six times more active than cisplatin against A549 cells after 24 h drug exposure. Cytotoxic potency towards A549 cells increased with phenyl substitution on Cp ring: Cpxbiph > Cpxph > Cp*. In addition, the biological studies showed that 3C caused cell apoptosis and cell cycle arrest at G1 phase in A549 cancer cells. Moreover, 3C increased the level of reactive oxygen species markedly after 24 h, which may provide an important basis for killing cancer cells. Confocal laser scanning microscopy was used to track 3C in A549 cells. The cellular localization experiment showed that 3C targeted lysosomes and caused lysosomal damage. 相似文献
65.
Mingxi Yang Yang Meng Junjun Liu Weixian Yu Bai Yang 《Particle & Particle Systems Characterization》2019,36(1)
Carbon dots (CDs), as an emerging fluorescent nanomaterial with low toxicity, has been widely applied in various bio‐related fields. However, investigations on their capabilities in guiding osteogenic differentiation are rarely seen, which has great significance in osteoporosis therapy and bone regeneration. Herein, for the first time, a new kind of Mg2+‐doped CDs is facilely synthesized through a one‐step hydrothermal method from metal gluconate salts. The CDs can serve as nanocarrier of Mg2+ ions entering into cells, and the bioessential metal ions subsequently stimulate osteoblastic differentiation by improving alkaline phosphatase (ALP) activity and upregulation related mRNA expression. Noteworthy, the raw material has almost negligible performance on osteoblastic differentiation compared to Mg‐CDs, which is due to the ultrasmall sizes of CDs and the efficient uptake by cells. Moreover, benefitting from the fluorescence properties, Mg‐CDs can also be applied as cell labeling agents. This work proposes a new strategy to synthesize multifunctional metal ion‐doped CDs, which might had great potential in serving as promising nanodrugs for bone loss therapy. 相似文献
66.
67.
Yu Liang Wen-Xuan Wang Xing Wu Meng Wang Chao-Jun Pu Zheng-Hui Li Tao Feng Juan He Ji-Kai Liu 《Tetrahedron letters》2019,60(28):1838-1840
Panisuffrutin A (1), a highly degraded seco-triterpene derivative, together with the known palbinone, has been isolated from the whole plant Paeonia suffruticosa var. papaveracea (Andr.) Kerner. The structure with absolute configuration of 1 was determined via comprehensive NMR and MS analyses, as well as NMR and ECD calculations. A plausible biosynthetic pathway for 1 was proposed. Compound 1 showed weak cytotoxicity against Hela cancer cell line with an IC50 value of 26.2 μM, while palbinone exhibited a moderate inhibition on NO production with an IC50 of 18.3 μM. 相似文献
68.
Long‐Zhang Dong Lei Zhang Jiang Liu Qing Huang Meng Lu Wen‐Xin Ji Ya‐Qian Lan 《Angewandte Chemie (International ed. in English)》2020,59(7):2659-2663
A series of stable heterometallic Fe2M cluster‐based MOFs ( NNU‐31‐M , M=Co, Ni, Zn) photocatalysts are presented. They can achieve the overall conversion of CO2 and H2O into HCOOH and O2 without the assistance of additional sacrificial agent and photosensitizer. The heterometallic cluster units and photosensitive ligands excited by visible light generate separated electrons and holes. Then, low‐valent metal M accepts electrons to reduce CO2, and high‐valent Fe uses holes to oxidize H2O. This is the first MOF photocatalyst system to finish artificial photosynthetic full reaction. It is noted that NNU‐31‐Zn exhibits the highest HCOOH yield of 26.3 μmol g?1 h?1 (selectivity of ca. 100 %). Furthermore, the DFT calculations based on crystal structures demonstrate the photocatalytic reaction mechanism. This work proposes a new strategy for how to design crystalline photocatalyst to realize artificial photosynthetic overall reaction. 相似文献
69.
Nonlinear Dynamics - This paper is concerned with the global regulation via output feedback for the time-delay nonlinear systems with unknown continuous output function and unknown growth rate.... 相似文献
70.
Mian Fu Xiaomei Zhuang Tianhong Zhang Ying Guan Qingbin Meng Yongjun Zhang 《Macromolecular bioscience》2020,20(9)
Leuprolide has been widely used in androgen deprivation therapy for the treatment of advanced prostate cancer, but its use is still limited due to its short half‐life. Herein, hydrogen‐bonded layer‐by‐layer films are fabricated from PEGylated leuprolide (PEG‐LEU) and tannic acid (TA). Because of its dynamic nature, the film disintegrates gradually in water and releases PEG‐LEU and TA. The in vitro release profile indicated perfect zero‐order kinetics, which is explained by the unique release mechanism. When implanted subcutaneously in male rats, the films maintain a constant serum drug level. For a 60‐bilayer film, the serum drug level is maintained constant for ≈24 days. No initial burst release is observed, suggesting that the in vivo release also follows zero‐order kinetics. Initially, an increase in the level of serum testosterone is induced by the released drug, followed by testosterone suppression to a constant level below the castrate level, which could be maintained as long as a constant serum drug level is maintained. Since the new drug carriers avoid an initial burst release of the drug and maintain a constant serum drug level and hence a constant serum testosterone level below the castrate level, these carriers are highly promising for androgen deprivation therapy. 相似文献