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排序方式: 共有416条查询结果,搜索用时 218 毫秒
1.
András Gy. Németh Renáta Szabó Dr. Attila Domján Prof. György M. Keserű Dr. Péter Ábrányi-Balogh 《ChemistryOpen》2021,10(1):16-27
The development of a new three-component chromatography-free reaction of isocyanides, amines and elemental sulfur allowed us the straightforward synthesis of thioureas in water. Considering a large pool of organic and inorganic bases, we first optimized the preparation of aqueous polysulfide solution from elemental sulfur. Using polysulfide solution, we were able to omit the otherwise mandatory chromatography, and to isolate the crystalline products directly from the reaction mixture by a simple filtration, retaining the sulfur in the solution phase. A wide range of thioureas synthesized in this way confirmed the reasonable substrate and functional group tolerance of our protocol. 相似文献
2.
Existence and Regularity of Periodic Solutions to Certain First-Order Partial Differential Equations
Adalberto?P.?BergamascoEmail author Paulo?L.?Dattori da Silva Rafael?B.?Gonzalez 《Journal of Fourier Analysis and Applications》2017,23(1):65-90
We present conditions on the coefficients of a class of vector fields on the torus which yield a characterization of global solvability as well as global hypoellipticity, in other words, the existence and regularity of periodic solutions. Diophantine conditions and connectedness of certain sublevel sets appear in a natural way in our results. 相似文献
3.
J.?Vanterler?da?C.?SousaEmail author E.?Capelas?de?Oliveira 《Mediterranean Journal of Mathematics》2017,14(6):244
In this paper, we introduce a new type of fractional derivative, which we called truncated \({\mathcal {V}}\)-fractional derivative, for \(\alpha \)-differentiable functions, by means of the six-parameter truncated Mittag–Leffler function. One remarkable characteristic of this new derivative is that it generalizes several different fractional derivatives, recently introduced: conformable fractional derivative, alternative fractional derivative, truncated alternative fractional derivative, M-fractional derivative and truncated M-fractional derivative. This new truncated \({\mathcal {V}}\)-fractional derivative satisfies several important properties of the classical derivatives of integer order calculus: linearity, product rule, quotient rule, function composition and the chain rule. Also, as in the case of the Caputo derivative, the derivative of a constant is zero. Since the six parameters Mittag–Leffler function is a generalization of Mittag–Leffler functions of one, two, three, four and five parameters, we were able to extend some of the classical results of the integer-order calculus, namely: Rolle’s theorem, the mean value theorem and its extension. In addition, we present a theorem on the law of exponents for derivatives and as an application we calculate the truncated \({\mathcal {V}}\)-fractional derivative of the two-parameter Mittag–Leffler function. Finally, we present the \({\mathcal {V}}\)-fractional integral from which, as a natural consequence, new results appear as applications. Specifically, we generalize the inverse property, the fundamental theorem of calculus, a theorem associated with classical integration by parts, and the mean value theorem for integrals. We also calculate the \({\mathcal {V}}\)-fractional integral of the two-parameter Mittag–Leffler function. Further, we were able to establish the relation between the truncated \({\mathcal {V}}\)-fractional derivative and the truncated \({\mathcal {V}}\)-fractional integral and the fractional derivative and fractional integral in the Riemann–Liouville sense when the order parameter \(\alpha \) lies between 0 and 1 (\(0<\alpha <1\)). 相似文献
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6.
WU Liting XIN Yujia GUO Zhaoyang GAO Wei ZHU Yanpeng br WANG Yinsong RAN Ruixue YANG Xiaoying 《高等学校化学研究》2022,38(2):562-571
Combining photothermal therapy and radiotherapy(PTT-RT) with reducing tumor hypoxia acts as an important antitumor modality. However, it is a great challenge to realize photothermal therapy, radiotherapy and exogenous oxygen supply in one nanosystem. To realize a combination of the three functions, we fabricated a red blood cell membrane(RBCm)-camouflaged, red blood cell content(RBCc) and the copper sulfide(CuS) co-loaded dendritic large pore mesoporous silica nanoparticle(DLMSN/CuS/RBCc/ RBCm). The cell membrane coating endowed the nanoparticles with good stability in the physiological environment, and CuS allowed the nanoparticle exhibiting good photothermal and radiosensitization properties. RBCc loaded nanoparticle DLMSN/CuS/RBCc enhanced superior anti-tumor effect than DLMSN/CuS during combined PTT-RT therapy because the introduction of RBCc increased the exogenous oxygen supply. The in vitro study further demonstrated that the combination of photothermal therapy and radiotherapy induced superior antitumor efficacy than single therapy. Our work thus presents a unique multifunctional nanoscale platform favorable for combined PTT and RT. 相似文献
7.
We construct open sets of C
k
(k ≥ 2) vector fields with singularities that have robust exponential decay of correlations with respect to the unique physical measure. In particular we prove that the geometric Lorenz attractor has exponential decay
of correlations with respect to the unique physical measure. 相似文献
8.
de Toledo RA Santos MC Cavalheiro ET Mazo LH 《Analytical and bioanalytical chemistry》2005,381(6):1161-1166
This work describes an electroanalytical investigation of dopamine using cyclic voltammetry (CV) and the graphite–polyurethane composite electrode (GPU). In CV studies, well-defined redox peaks characterize the oxidation process at the GPU electrode, which is indicative of electrocatalytic effects associated with active sites on the GPU electrode surface. A new analytical methodology was developed using the GPU electrode and square wave voltammetry (SWV) in BR buffer solution (0.1 mol L–1; pH 7.4). Analytical curves were constructed under optimized conditions (f=60s–1, Ea=50 mV, EI=2 mV) and detection and quantification limits of 6.4×10–8 mol L–1 (12.1 g L–1) and 5.2×10–6 mol L–1 (0.9 mg L–1), respectively, were achieved. The precision of the method was checked by performing ten successive measurements for a 9.9×10–6 mol L–1 dopamine solution. For intra-assay and inter-assay precisions, the relative standard deviations were 1.9 and 2.3%, respectively. In order to evaluate the developed methodology, the determination of dopamine was performed with good sensitivity and selectivity, without the interference of ascorbic acid in synthetic cerebrospinal fluid, which indicates that the new methodology enables reliable analysis of dopamine. 相似文献
9.
L.?S.?Roman R.?M.?Q.?Mello F.?Cunha I.?A.?HümmelgenEmail author 《Journal of Solid State Electrochemistry》2004,8(2):118-121
We report the use of sulfonated polyaniline, SPAN, as a positive charge transporting layer in organic electronic devices, demonstrating that it can be used to significantly improve injection into conjugated polymers. The introduction of an intermediate SPAN layer improves device rectification, even when low-work-function anode materials such as tin oxide are used. 相似文献
10.
Bohumír Grüner Jaroslav Ba?kovský Bohumil Štíbr 《Journal of organometallic chemistry》2005,690(11):2850-2852
The compounds with a single and double -CH2C6H4CH2- spacer, [CpFeC3B8H10-NH-CH2C6H4CH2-NH-C3B8H10FeCp] and [CpFeC3B8H10-N-(CH2C6H4CH2)2-N-C3B8H10FeCp], represent the first example of designed shaping by extremely stable cyclopentadienyl-ferratricarbollide (CpFeTCB) cages into rigid molecular constructions approaching linear arrangement. 相似文献