排序方式: 共有53条查询结果,搜索用时 31 毫秒
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JingLu Ma Qian Yue ShinTed Lin Henry Tsz-King Wong JinWei Hu LiPing Jia Hao Jiang Jin Li ShuKui Liu ZhongZhi Liu Hao Ma WeiYou Tang Yang Tian Li Wang Qing Wang Yi Wang LiTao Yang Zhi Zeng 《中国科学:物理学 力学 天文学(英文版)》2019,(1)
A study on cosmogenic activation in germanium was carried out to evaluate the cosmogenic background level of natural and ~(70)Ge depleted germanium detectors. The production rates of long-lived radionuclides were calculated with Geant4 and CRY.Results were validated by comparing the simulated and experimental spectra of CDEX-1B detector. Based on the validated codes, the cosmogenic background level was predicted for further tonne-scale CDEX experiment. The suppression of cosmogenic background level could be achieved by underground germanium crystal growth and high-purity germanium detector fabrication to reach the sensitivity requirement for direct detection of dark matter. With the low cosmogenic background, new physics channels,such as solar neutrino research and neutrinoless double-beta decay experiments, were opened and the corresponding simulations and evaluations were carried out. 相似文献
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利用全细胞膜片钳技术,研究了稀土镧离子对非兴奋性小鼠成骨细胞(MC3T3)钙激活外向钾电流及其激活和失活动力学的影响.结果表明:MC3T3细胞钙激活外向钾电流随着电极内液中游离Ca2+浓度的增加而增加,且具有电压和胞内游离Ca2+依赖性特征.细胞外液中的稀土镧可浓度依赖性地抑制MC3T3细胞钙激活外向钾电流,其半数抑制浓度(EC50)为8.23±1.45μmol/L.50μmol/L氯化镧可使钾电流的激活曲线向正电位方向移动,而使其失活曲线向负电位方向移动,但对激活曲线和失活曲线的斜率因子k值影响都不大.研究表明:抑制钾通道电流,可使细胞膜去极化,细胞的兴奋性增加,从而增加胞外Ca2+向胞内流动,引起胞内Ca2+浓度的增加,由此而诱发一系列的生理和分子生物学事件.这一过程可能是稀土镧影响MC3T3成骨细胞生长和功能的分子作用机制之一. 相似文献
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设D 是带对合的除环. 当char(D) ≠ 2 时, D 上Hermitian 矩阵几何的基本定理最近已经证明.作者进一步证明了特征2 的带对合的除环上Hermitian 矩阵几何的基本定理, 从而得到任意带对合的除环上Hermitian 矩阵几何的基本定理. 相似文献
35.
Haimei FanDejun Wang Lingling Wang Haiyan LiPing Wang Tengfei JiangTengfeng Xie 《Applied Surface Science》2011,257(17):7758-7762
Different morphologies of monoclinic BiVO4 with smaller size were hydrothermal synthesized by simply adjusting the amount of surfactant (polyvinyl pyrrolidone PVP K30) added. The detailed field emission scanning electron microscope (FESEM) analysis revealed that the amount of PVP added could significantly affect the morphology and size of BiVO4. Their photocatalytic activities were evaluated by the decolorization of methylene blue (MB) aqueous solution under visible-light irradiation (λ > 400 nm), and the as-prepared sample with well-assembled flower-like morphology showed a much higher photocatalytic activity due to larger specific surface area and higher separation efficiency of photo-induced carriers. The relationship between the behavior of photo-induced carriers and photocatalytic activity was studied using the surface photovoltage spectroscopy (SPS) and corresponding phase spectra. 相似文献
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A novel type of glucose sensor was fabricated based on a glucose oxidase (GOD)-N,N-dimethtylformamide (DMF)-[BMIm][BF4] composites modified three-dimensional ordered macroporous (3DOM) gold film electrode. The immobilized GOD exhibits a pair
of well-defined reversible peaks in 50 mM pH 7.0 phosphate buffer solutions (PBS), which could be attributed to the redox
of flavin adenine dinucleotide (FAD) in GOD. The research results show that ionic liquid ([BMIm][BF4]), DMF and 3DOM gold film are crucial for GOD to exhibit a pair of stable and reversible peaks. It is believed that the large
active area of 3DOM gold film can increase the amount of immobilized GOD. Simultaneously, the application of IL enhances the
stability of GOD and facilitates the electron transfer between GOD and the electrode. The synergetic effect of DMF can help
the GOD to maintain its bioactivity better. GOD immobilized on the electrode exhibits the favorable electrocatalytic property
to glucose, and the prepared sensor has a linear range from 10 to 125 nM with a detection limit of 3.3 nM at a signal-to-noise
ratio of 3σ. The apparent K
m (Michaelis- Menten constant) for the enzymatic reaction is 0.018 mM. 相似文献
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While a great deal of research has focused on the application of full-sequence ionic complementary peptide, detection of the
capability of half-sequence ionic complementary peptide such as drug carriers, is rarely reported. This paper presents that
the half-sequence ionic complementary peptide P9 (AC-Pro- Ser-Phe-Asn-Phe-Lys-Phe-Glu-Pro-NH2) can successfully stabilize
a model hydrophobic drug pyrene in the aqueous solution. Soybean lecithin vesicles were used to mimic plasma membranes. Fluorescence
data show that the pyrene is presented in the crystalline form when stabilized by P9 solution, and molecularly migrated from
its peptide encapsulations into the membrane bilayers when the suspension is mixed with lipidosome vesicles. Slower release
was observed when thicker coating was applied onto pyrene, which could be to control the wall thickness coating the cargo,
and consequently the release rate. The result indicated that P9, with half-sequence ionic complement, may serve as a hydrophobic
compounds carrier.
Supported by the National ‘985 Project’ of Ministry of Education of China 相似文献
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A single anthryl appended meso-tetraphenylporphyrin (TPP) dyad has been synthesized and applied in fluorescence sensing of
iodine based on the intramolecular excitation energy transfer. The molecular recognition of the sensor is based on the interaction
of iodine with inner anthracene moiety of the dyad, while the signal reporter for the recognition process is the TPP fluorescence
quenching. Because the emission spectrum of anthracene is largely overlapped with the Soret band absorption of TPP, intramolecular
excitation energy transfer interaction occurs between the donor, anthracene and acceptor, TPP. This energy transfer leads
to TPP fluorescence emission by excitation of anthracene. The sensor was constructed by immobilizing the dyad in a plasticized
poly(vinyl chloride) (PVC) membrane. The sensing membrane shows higher sensitivity compared to the sensors by using anthracene,
TPP, or a mixture of anthracene and TPP as sensing materials. Under the optimum conditions, iodine in a sample solution can
be determined from 2.04 to 23.6 mmol·L−1 with a detection limit of 33 nmol·L−1. The sensing membrane shows satisfactory response characteristics including good reproducibility, reversibility and stability,
as well as the short response time of less than 60 s. Except for Cr2O72− and MnO4−, other common metal ions and anions in foodstuff do not interfere with iodine determination. The proposed method was applied
in the determination of iodine in table salt samples. The results agree well with those obtained by other methods.
Supported by the National Outstanding Youth Science Foundation of China (Grant No. 20525518), the National Natural Science
Foundation of China (Grant No. 20775005), and the National Natural Science Foundation of Hunan province (Grant No. JJ076021) 相似文献
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Large dimensional predictors are often introduced in regressions to attenuate the possible modeling bias. We consider the stable direction recovery in single-index models in which we solely assume the response Y is independent of the diverging dimensional predictors X when βτ 0 X is given, where β 0 is a p n × 1 vector, and p n →∞ as the sample size n →∞. We first explore sufficient conditions under which the least squares estimation β n0 recovers the direction β 0 consistently even when p n = o(√ n). To enhance the model interpretability by excluding irrelevant predictors in regressions, we suggest an e1-regularization algorithm with a quadratic constraint on magnitude of least squares residuals to search for a sparse estimation of β 0 . Not only can the solution β n of e1-regularization recover β 0 consistently, it also produces sufficiently sparse estimators which enable us to select "important" predictors to facilitate the model interpretation while maintaining the prediction accuracy. Further analysis by simulations and an application to the car price data suggest that our proposed estimation procedures have good finite-sample performance and are computationally efficient. 相似文献