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排序方式: 共有123条查询结果,搜索用时 31 毫秒
71.
Large amplitude motion of methyl groups in isolated molecules is a fundamental phenomenon in molecular physics. The methyl torsional barrier is sensitive to the steric and electronic environment in the surrounding of the methyl group, making the methyl group a detector of the molecular structure. To probe this effect, the microwave spectrum of 2,6-dimethylfluorobenzene, one of the six isomers of dimethylfluorobenzene, was measured using two pulsed molecular jet Fourier transform microwave spectrometers operating in the frequency range from 2 to 40 GHz. Due to internal rotations of two equivalent methyl groups with relatively low torsional barriers, all rotational transitions split into quartets with separations of up to several hundreds of MHz. The splittings were analyzed and modeled to deduce a torsional barrier of 236.7922 (21) cm−1. The results are compared to those obtained from quantum chemical calculations and with other fluorine substituted toluene derivatives of the current literature where the methyl group is adjacent to a fluorine atom. 相似文献
72.
H. Safa F. Damoy O. Gal B. Poumarède A. Curtoni L. Delgove J. Plasmans 《Journal of Radioanalytical and Nuclear Chemistry》2007,271(1):241-246
Nuclear waste management cost at CEA is a heavy budget share. Therefore, it is important, in order to minimize that cost,
to select the most suitable repository for the waste. Significant cost savings are obtained, for example, whenever a medium
activity waste drum initially filed to end up in a geological repository can be measured accurately enough to be accepted
by the Centre de Stockage de l’Aube (CSA). Photofission can be used as a non-destructive technique to measure the actinide
content embedded in a nuclear waste drum. It can even be applied when the waste is packaged in its heavy concrete shielding.
It is equally sensitive to non-fissile nuclear material. However, the present state of art suffers from a lack of sensitivity
to be able to help redirecting the waste to the proper repository. A new program called INPHO is proposed at CEA Saclay aiming
at enhancing the sensitivity sufficiently to be applicable for waste characterization. 相似文献
73.
Safa Bouazza 《International journal of quantum chemistry》2011,111(12):3000-3007
The fine structure of the even‐parity low configurations has been reanalyzed by simultaneous parameterization of the one‐ and two‐body interactions for the model space (4d + 5s)3. Using the calculated eigenfunctions, the magnetic‐dipole A hyperfine constants for the whole 37 existing levels of the model space were predicted and compared partially to those obtained using relativistic configuration‐interaction approach. Moreover, volume shifts (VS) and specific mass shifts (SMS) of numerous configurations of singly ionised zirconium are deduced by means of ab initio estimates combined with a few experimental isotope shift data available in literature: VS(4d15s2) = 840 MHz, VS(4d3) = ?649 MHz, VS(4d15p2) = ?387 MHz, VS(5s25p1) = 1250 MHz, and SMS(4d15s2) = ?634 MHz, SMS(4d3) = 484 MHz, SMS(5s25p1) = ?1459 MHz, referred to 4d25s for the pair Zr90–Zr92. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2011 相似文献
74.
Starting from resin-bound orthogonally protected lysine, the generation of 19-membered ring macro-heterocycles via intramolecular thioether formation is described. The on resin cyclization occurred by the coupling of p-fluoro-m-nitro benzoic acid or bromo acetic acid followed by intramolecular substitution SNAr or SN2 displacement of the fluoro and bromo groups, respectively. The described approaches present versatile synthetic routes toward the synthesis of libraries of macro-heterocycles in an attempt to establish lead drug candidates. The desired cyclic products were obtained in good yields and good purities. 相似文献
75.
Fatih Safa Erenay Ihsan Sabuncuoglu Ayşegül Toptal Manoj Kumar Tiwari 《European Journal of Operational Research》2010
We consider the bicriteria scheduling problem of minimizing the number of tardy jobs and average flowtime on a single machine. This problem, which is known to be NP-hard, is important in practice, as the former criterion conveys the customer’s position, and the latter reflects the manufacturer’s perspective in the supply chain. We propose four new heuristics to solve this multiobjective scheduling problem. Two of these heuristics are constructive algorithms based on beam search methodology. The other two are metaheuristic approaches using a genetic algorithm and tabu-search. Our computational experiments indicate that the proposed beam search heuristics find efficient schedules optimally in most cases and perform better than the existing heuristics in the literature. 相似文献
76.
Gholamhosseini-Nazari Mahdi Esmati Somayeh Safa Kazem D. Khataee Alireza Teimuri-Mofrad Reza 《Research on Chemical Intermediates》2019,45(4):1841-1862
Research on Chemical Intermediates - In this study, a novel magnetically recoverable Fe3O4@SiO2-BenzIm-Fc[Cl]/ZnCl2 nano-particle was synthesized using a simple chemical coprecipitation approach.... 相似文献
77.
F. Ibrahim J. Obert O. Bajeat J.M. Buhour D. Carminati F. Clapier C. Donzaud M. Ducourtieux J.M. Dufour S. Essabaa S. Galès D. Guillemaud-Mueller F. Hosni O. Hubert A. Joinet U. Köster C. Lau H. Lefort G. Le Scornet J. Lettry A.C. Mueller M. Mirea N. Pauwels O. Perru J.C. Potier J. Proust F. Pougheon H. Ravn L. Rinolfi G. Rossat H. Safa M.G. Saint Laurent M. Santana-Leitner O. Sorlin D. Verney 《The European Physical Journal A - Hadrons and Nuclei》2002,15(3):357-360
A PARRNe 1 experiment (Production d'Atomes Radioactifs Riches en Neutrons) aimed at the production of neutron-rich radioactive
noble gases produced by photofission has been performed at CERN. The LEP Pre-Injector (LPI) has been used to deliver a 50
MeV electron beam. The results obtained show clearly that the use of an electron beam to produce neutron-rich fission fragments
for futur RNB facilities is an option that should not be neglected.
Received: 20 July 2001 / Accepted: 5 June 2002 / Published online: 19 November 2002
RID="a"
ID="a"e-mail: ibrahim@ipno.in2p3.fr
Communicated by D. Guerreau 相似文献
78.
Maryam Haroon Al-Soufi Hussah Abdullah Alshwyeh Haifa Alqahtani Safa Khalil Al-Zuwaid Fatimah Othman Al-Ahmed Fatima Taher Al-Abdulaziz Daniya Raed Khaoula Hellal Nurul Hidayah Mohd Nani Siti Norliyana Zubaidi Nurul Syahidah Mio Asni Hamizah Shahirah Hamezah Nurkhalida Kamal Hessah Al-Muzafar Ahmed Mediani 《Molecules (Basel, Switzerland)》2022,27(15)
Fruits maintain the image as the richest sources of vitamins. Focusing on apricots, utilization of apricot species for many applications is possible due to its various benefits. Many research studies demonstrated different perspectives of apricot, especially in medical used as it can act as antioxidant, anti-inflammatory, and antimicrobial agents. Moreover, in the industrial sectors, apricots can be used in the production of biofuels and batteries. All components of the apricot fruit, including seeds and kernels have been found to possess significant interest. This review is to breach the knowledge gap regarding the key nutrients and chemicals of apricot fruit, contributing to its health-promoting properties to emphasize the noble importance of this fruit in the diet and in the management of several diseases. We also cover the application of apricots in the industry that could be developed as a promising and sustainable source. 相似文献
79.
Design and synthesis of new pyrazole, pyrimidinthione, and triazepinthione derivatives via heterocyclic ring opening of azacoumarin were promoted with grinding and ultrasonic reaction conditions. Efficient solventless one‐pot synthesis can be well progressed to afford the good yield of new heterocyclic products that were characterized by IR, 1H‐NMR, MS, and microanalytical data. Anticancer evaluation for the synthesized compounds exhibited moderate to good cytotoxicity such as pyrazole derivatives 5 , 9 , and 14 that displayed best cytotoxic activities with IC50 8.16 ± 1.1, 7.02 ± 0.6, and 5.12 ± 0.41 μg/mL and 9.28 ± 0.7, 6.45 ± 0.9, and 5.85 ± 0.26 μg/mL for MCF‐7 and WI cells, respectively. Pyrimidine derivatives 6 , 11 , and 15 exhibited strong cytotoxicity with IC50 8.9 ± 0.62, 7.16 ± 0.5, and 7.72 ± 0.41 μg/mL against MCF‐7. 相似文献
80.
Mahdi Gholamhosseini‐Nazari Somayeh Esmati Kazem D. Safa Alireza Khataee Reza Teimuri‐Mofrad 《应用有机金属化学》2019,33(4)
A novel magnetic ferrocene‐labelled ionic liquid based on triazolium, [Fe3O4@SiO2@Triazol‐Fc][HCO3], has been synthesized and has been successfully introduced as a recyclable heterogeneous nanocatalyst. The catalytic activity of the novel magnetic nanoparticles was evaluated in the one‐pot three‐component synthesis of a wide variety of Betti bases. A simple, facile and highly efficient green method has been developed for the synthesis of kojic acid‐containing Betti base derivatives at room temperature. Additionally, this new protocol has notable advantages such as short reaction times, green reaction conditions, high yields and simple workup and purification steps. Also, the novel nanocatalyst could be easily recovered using an external magnetic field and reused for six consecutive reaction cycles without significant loss of activity. The newly synthesized nanocatalyst was characterized using Fourier transform infrared spectroscopy, X‐ray diffraction, energy‐dispersive X‐ray spectroscopy, field emission scanning electron microscopy, transmission electron microscopy and Brunauer–Emmett–Teller measurements. 相似文献