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排序方式: 共有433条查询结果,搜索用时 15 毫秒
1.
An electron-emission theoretical model integrating the change in the grain size of nanocrystalline cubic boron nitride (c-BN) thin films was established. To understand better the essence of field emission, an accurate numerical scheme, the transfer matrix method, that can be used to compute the tunneling coefficients of the actual surface barrier, was also adopted. The present results show that the emission current from nanocrystalline grain films is far larger than that from regular grain films or bulk c-BN. 相似文献
2.
Demosthenes Kivotides 《Journal of Low Temperature Physics》2007,148(3-4):287-291
We analyse a numerical solution of a mathematical model of thermal superfluid turbulence. We elaborate on key points of the
statistical phenomenology and point out their impact on fundamental issues of general turbulence theory. 相似文献
3.
We study dynamics of quantized vortex lattice formation in a rotating Bose-Einstein condensate with a square blue-detuned
optical lattice by solving the Gross-Pitaevskii equation. This dynamics depends on the depth of the optical lattice. Vortices
tend to form a triangular lattice under the rotation, while an optical lattice likes to pin vortices at their peaks. Such
a competition of two effects makes this system more interesting and complicated. 相似文献
4.
Eugene Choi Sung Jean Park Gunhee Lee Seung Kew Yoon Minho Lee Suk Kyeong Lee 《International journal of molecular sciences》2021,22(6)
Hepatocellular carcinoma (HCC), the most common malignant tumor in the liver, grows and metastasizes rapidly. Despite advances in treatment modalities, the five-year survival rate of HCC remains less than 30%. We sought genetic mutations that may affect the oncogenic properties of HCC, using The Cancer Genome Atlas (TCGA) data analysis. We found that the GNAQ T96S mutation (threonine 96 to serine alteration of the Gαq protein) was present in 12 out of 373 HCC patients (3.2%). To examine the effect of the GNAQ T96S mutation on HCC, we transfected the SK-Hep-1 cell line with the wild-type or the mutant GNAQ T96S expression vector. Transfection with the wild-type GNAQ expression vector enhanced anchorage-independent growth, migration, and the MAPK pathways in the SK-Hep-1 cells compared to control vector transfection. Moreover, cell proliferation, anchorage-independent growth, migration, and the MAPK pathways were further enhanced in the SK-Hep-1 cells transfected with the GNAQ T96S expression vector compared to the wild-type GNAQ-transfected cells. In silico structural analysis shows that the substitution of the GNAQ amino acid threonine 96 with a serine may destabilize the interaction between the regulator of G protein signaling (RGS) protein and GNAQ. This may reduce the inhibitory effect of RGS on GNAQ signaling, enhancing the GNAQ signaling pathway. Single nucleotide polymorphism (SNP) genotyping analysis for Korean HCC patients shows that the GNAQ T96S mutation was found in only one of the 456 patients (0.22%). Our data suggest that the GNAQ T96S hotspot mutation may play an oncogenic role in HCC by potentiating the GNAQ signal transduction pathway. 相似文献
5.
Mario Gleria Roberta Bertani Roger De Jaeger 《Journal of Inorganic and Organometallic Polymers》2004,14(1):1-28
A general survey of fluorinated phosphazene polymers starting from their synthesis in 1965 to recent times is presented. Various types of fluorinated phosphazenes are described depending on the way fluorine atoms are connected to the polyphosphazene skeleton. The characterization, properties and practical utilization of these compounds in different domains are critically discussed. 相似文献
6.
K. G. Shkadinskii N. I. Ozerkovskaya S. V. Kostin 《Combustion, Explosion, and Shock Waves》2004,40(3):285-294
The specific features of dynamics of the thermal explosion in systems porous reagent–active gas–solid product under conditions where the heattransfer and masstransfer regions are separated from the ambient medium are considered. In addition to the competition of heat release and heat removal, the process of initiation of exothermal chemical interaction in these systems under normal pressures depends significantly on conditions of filtration transport of the gaseous reagent. The induction and postinduction periods of the thermal explosion are studied. The theoretical analysis of thermalexplosion issues is supplemented by an experimental study of the process for the porous titanium–nitrogen–titanium nitride system. 相似文献
7.
Systems of Pd supported on various La2O3-modified -Al2O3 and CeO2–Al2O3 catalysts were tested for catalytic methanol decomposition and characterized by means of XRD, BET, TPR, H2-chemisorption and CO–FTIR. The addition of lanthanum significantly improved the selectivity of CO and H2 for all the catalysts but showed a different influence on the catalytic activity in two systems. Methanol conversion decreased on La2O3-modified Pd/-Al2O3 catalysts, in line with the reduction of Pd dispersion, while the addition of La2O3 improved the dispersion of Pd and reinforced Pd–CeO2 interaction for La2O3-modified Pd/CeO2–Al2O3 catalysts, which resulted in a high production rate of CO and H2. Thus, a synergistic effect between CeO2 and La2O3 was observed on -Al2O3-supported Pd catalyst for methanol decomposition. 相似文献
8.
Two of the majorNuphar alkaloids, nupharolutine and 6,6-dihydroxythiobinupharidine, were isolated from the aquatic perennial herbNuphar lutea (L.) Sibth. & Sm., yellow water lily. In a lettuce seedling bioassay of the two pure compounds, the former was inactive and the latter was highly inhibitory of radicle elongation at concentrations greater than 2 ppm. Structures and stereochemistry of the two compounds were confirmed by DEPT,1H-1H COSY,1H-13C COSY, and1H-1H NOESY experiments. 相似文献
9.
The white pine cone beetle, Conophthorus coniperda, exhibited dose and enantiospecific responses to -pinene in stands of mature eastern white pine, Pinus strobus, in a seed orchard near Murphy, North Carolina, USA. (–)--Pinene significantly increased catches of cone beetles to traps baited with (± )-trans-pityol. (+)--Pinene did not increase catches of beetles to pityol-baited traps and interrupted the response of beetles to traps baited with (±)-trans-pityol and (–)--pinene. Maximal attraction of cone beetles to pityol-baited traps was obtained with lures releasing (–)--pinene at a rate of 103 mg/day at 23°C. Lures releasing (–)--pinene at rates lower or higher than 103 mg/day resulted in reduced catches to traps baited with (±)-trans-pityol. The sex ratio in all catches was heavily male biased. Attraction of the clerid predator, Thanasimus dubius, to traps baited with (±)-trans-pityol increased significantly with the presence of -pinene, irrespective of enantiomeric composition. Maximal attraction of T. dubius to pityol-baited traps occurred with devices releasing (–)--pinene at the highest rate tested, 579 mg/d at 23°C, a sub optimal rate for cone beetles. 相似文献
10.
深空通信系统中高阶LDPC码的软定时同步算法 总被引:1,自引:1,他引:0
深空通信具有信号衰减严重,接收机信噪比低的特点,针对深空通信系统中高阶LDPC码定时同步实现困难的问题,提出一种码辅助定时同步算法.首先使用高阶LDPC码的译码软信息构造一种代价函数,进行大定时偏移的粗同步,其次基于最大似然准则,使用EM算法进行定时偏移的细同步.该算法将定时同步器、解调器与译码器联合迭代,利用高阶LDPC译码器输出的软信息辅助定时同步,并通过数字插值方式对过采样信号进行补偿,从而得到接近修正克拉美罗限的定时估计.仿真结果表明,在低信噪比条件下,算法能够在较大定时偏移范围内实现有效的定时同步,并以较低的复杂度获得近似理想的系统误码率性能. 相似文献