排序方式: 共有64条查询结果,搜索用时 15 毫秒
51.
Nadjia Haouari Wafaa Batat Noureddine Rahmani Salima Rahmani 《Mediterranean Journal of Mathematics》2008,5(1):113-131
We give a complete classification of three-dimensional naturally reductive Lorentzian spaces, using a classification of the
self adjoint Ricci operators.
相似文献
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A means of generating latices with solid contents well over 70% (v/v) without the use of intermediate seeds is proposed. It is demonstrated that the use of an electrically neutral initiation system (hydrogen peroxide) in the initial stages of the process, followed by an initiator yielding negatively charged free radicals (ammonium persulphate) changes the way in which the system generates stable particles. The reason for this change is the need to avoid stabilising small, homogeneously nucleated particles during the first portion of the process, and the desire to generate controlled quantities of them during the second portion. The processes are highly reproducible, as are the particle size distributions and rheological properties of the final latices. 相似文献
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Mohamed Bouhrim Salima Boutahiri Loubna Kharchoufa Hamza Mechchate Omkulthom Mohamed Al Kamaly Ali Berraaouan Bruno Eto Abderrahim Ziyyat Hassane Mekhfi Abdelkhaleq Legssyer Mohammed Aziz Mohamed Bnouham 《Molecules (Basel, Switzerland)》2021,26(8)
This study aims to assess the safety of the Opuntia dillenii (Ker-Gawl) haw. seed oil (ODSO) and its effect on the glucose absorption activity of the isolated rat hemidiaphragm. This oil’s safety was studied by exploring its acute (doses 1, 3, 5, and 7 mL/kg) and subacute (doses 1 and 2 mL/kg) toxicities in albino mice and Wistar rats, respectively. The safety of the ODSO was also assessed by studying its effect on the HepG2 cell viability in vitro. The effect of ODSO, or combined with the insulin, on the glucose absorption activity of isolated rat hemidiaphragm was evaluated at the dose 1 g/L in vitro. The results demonstrated the safety of ODSO. Indeed, this study showed that this oil does not produce any mortality or signs of toxicity after the single-dose administration in mice. Additionally, the daily intake of the ODSO during four weeks does not induce a significant variation in the biochemical parameters and body weight of rats compared with the control group. Besides, the cell viability of HepG2 did not change in the presence of ODSO. On the other hand, the ODSO increased the glucose absorption activity of the isolated rat hemidiaphragm, and this activity was significantly enhanced when combined with insulin. This study confirms, on one side, the safety of this oil and its efficacy and, on the other side, encourages its potential use as a complement to treat diabetes. 相似文献
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Nadav Genossar-Dan Sharona Atlas Dana Fux Shani Har Lavan Uri Zamir Dr. Illya Rozenberg Dr. Thanh Lam Nguyen Dr. Patrick Hemberger Dr. Joshua H. Baraban 《Angewandte Chemie (International ed. in English)》2023,62(32):e202305881
We report the first direct detection of ethyl radical in the pyrolysis of ethane. Observation of this vital intermediate was made possible in this extremely reactive environment by the use of a microreactor coupled with synchrotron radiation and photoelectron photoion coincidence (PEPICO) spectroscopy, despite its short lifetime and low concentration. Together with ab-initio master equation-calculated rates and fully coupled computational fluid dynamics simulations, our measurements show that even under the low pressures and short residence times in our experiment, ethyl formation can only be explained by bimolecular reactions; the most important is the catalytic attack of ethane by H atoms, which are then regenerated by decomposition of the nascent ethyl radicals. Our results complete the observation of all hypothesized intermediates in this industrially important process and highlight the need for further studies under additional conditions using similar methods to improve existing models and optimize process chemistries. 相似文献
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Shahidzadeh-Bonn N Rafaï S Bonn D Wegdam G 《Langmuir : the ACS journal of surfaces and colloids》2008,24(16):8599-8605
Salt damage in stone results in part from crystallization of salts during drying. We study the evaporation of aqueous salt solutions and the crystallization growth for sodium sulfate and sodium chloride in model situations: evaporating droplets and evaporation from square capillaries. The results show that the interfacial properties are of key importance for where and how the crystals form. The consequences for the different forms of salt crystallization observed in practice are discussed. 相似文献
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When confining vacuum fluctuations between two identical walls, the Casimir force manifests itself as a mutual attraction of the walls. When confining concentration fluctuations of a binary liquid mixture, an analogous force should exist near the critical temperature TC; it is called the critical Casimir force. Here we show experimentally that this purely entropic force can be either attractive or repulsive, depending on the boundary conditions for the fluctuations. For symmetrical boundary conditions an attractive force is found while asymmetrical ones lead to a repulsive force. This is observed directly by confining the fluctuations in a thin wetting film. Depending on the boundary conditions either a thinning or a thickening of the film is observed when T→TC. 相似文献
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Abdelhamid Benmezaï Salima Mechrouk 《NoDEA : Nonlinear Differential Equations and Applications》2013,20(3):489-510
We provide in this paper existence results for positive solution to the abstract Hammerstein equation NFu = u where N : E → E is a completely continuous operator, F : C → C is a continuous and bounded map and C is a cone in the Banach space E. The obtained results are used to prove existence results for positive solution to ${\phi}$ -Laplacian boundary value problem. 相似文献
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