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Nonlinear feedback shift registers (NFSRs) are widely used in stream cipher design as building blocks. The cascade connection of NFSRs, known as an important architecture, has been adopted in Grain family of stream ciphers. In this paper, a new sufficient condition under which an NFSR cannot be decomposed into the cascade connection of two smaller NFSRs is presented, which is easy to be verified from the algebraic normal form (ANF) of the characteristic function. In fact, our results are also applicable to nonsingular Boolean functions, which actually improve a previous research of Rhodes [6] where the characteristic functions of NFSRs cannot be contained. 相似文献
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Liu Zhu Sun Wen-Yang Fan Xiao-Gang Wang Dong Ye Liu 《International Journal of Theoretical Physics》2021,60(7):2412-2422
International Journal of Theoretical Physics - In this paper, we investigate Einstein-Podolsky-Rosen steering, Bell non-locality, first-order coherence and concurrence in the spin- $\frac {1}{2}$... 相似文献
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Acta Mathematicae Applicatae Sinica, English Series - So far there have been few results presented on the exponential stability for time-changed stochastic differential equations. The main aim of... 相似文献
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Wen-Wen Zi Zihao Gao Prof. Jun Zhang Bao-Xun Zhao Xian-Shu Cai Prof. Hong-Bin Du Prof. Fei-Jian Chen 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(10):3976-3979
Extra-large-pore zeolites for processing large molecules have long been sought after by both the academia and industry. However, the synthesis of these materials, particularly extra-large-pore pure silica zeolites, remains a big challenge. Herein we report the synthesis of a new extra-large-pore silica zeolite, designated NUD-6, by using an easily synthesized aromatic organic cation as structure-directing agent. NUD-6 possesses an intersecting 16×8×8-membered ring pore channel system constructed by four-connected (Q4) and unusual three-connected (Q3) silicon species. The organic cations in NUD-6 can be removed in nitric acid to yield a porous material with high surface area and pore volume. The synthesis of NUD-6 presents a feasible means to prepare extra-large pore silica zeolites by using assembled aromatic organic cations as structure-directing agents. 相似文献
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《中国化学快报》2020,31(5):1317-1321
Dipyrrolyldiketone difluoroboron complexes (BONEPYs) were synthesized by condensation of the corresponding pyrroles and malonyl chloride followed by treatment with BF3·OEt2. The aryl-substituted pyrrole is introduced to form a cyclic system in order to investigate anion binding studies. In BONEPYs 1–3 the o-H of the aryl group forms hydrogen bonding with F− to give a more table complex. In contrast, the intramolecular hydrogen-bonded BONEPY endo-4 is more stable than its exo isomer. While adding F−, the hydrogen bonds must be broken first to give 4·(3)F−. Owing to the electron-rich group (-OMe), the o-H of the phenyl group can hardly interact with F− via hydrogen bonding to give the less stable complex 4·(5)F−. The energy differences between the different conformations were calculated using DFT methods, which is consistent to the experimental observations. 相似文献
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一类时滞捕食系统的Hopf分支 总被引:1,自引:1,他引:0
研究了一类具有修正的Leslie-Gower和Holling-IV类功能性反应函数的时滞捕食系统,讨论了该系统的局部稳定性和Hopf分支存在性, 并利用中心流形定理和规范型理论确定了Hopf分支的方向和分支周期解的稳定性.仿真实例证明了理论分析结果的正确性. 相似文献
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以2,4,6-三(1-吡唑基)-1,3,5-三嗪(TPTz)与不同金属离子进行溶剂热反应,得到了3个氢键连接的金属-有机网状化合物。实验发现TPTz的水解产物6-(1-吡唑基)-1,3,5-三嗪-2,4-二酚(H2L)在反应中起到了实际的配位作用。单晶结构分析表明,它们是同构化合物,分子式为[M(HL)2]·2H2O(M=Zn,1;Co,2;Mn,3)。每个中心金属原子分别与2个吡唑基上的N、2个吡嗪环上的N和2个水分子中的O形成六配位的结构。2个HL-与1个中心金属配位形成一个零维的金属-有机配合物小分子,这些小分子通过氢键连接进一步拓展为二维层状结构。紫外-可见漫反射(UV-VisDRS)分析结果表明,这3种化合物都是宽系半导体材料,其带隙宽度分别为3.80(Zn),3.30(Co),3.27(Mn)eV,其半导体性质同中心金属原子表现出明显的相关性。 相似文献
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在分子筛的合成中,通过使用四咪唑基取代的硼类化合物(四咪唑硼钠)作为模板剂,在溶剂热条件下,成功得到了磷酸铝盐分子筛AlPO4-11的大单晶。电喷雾质谱、19F和11B NMR等研究结果表明,在溶剂热条件下四咪唑硼钠起到了缓释剂的作用,其自身经历缓慢分解,持续释放低浓度咪唑分子的过程。由其释放出来的咪唑分子起到事实上的模板作用。因其浓度较低,限制了分子筛结晶过程中晶核形成的数量,从而易于导向分子筛大单晶的生成。通过引入不同种类的四取代硼类化合物作为模板剂,这种分子筛大单晶的合成策略可潜在应用于其它分子筛材料。 相似文献
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