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排序方式: 共有423条查询结果,搜索用时 15 毫秒
1.
Bose G Nguyen VT Ullah E Lahiri S Görls H Langer P 《The Journal of organic chemistry》2004,69(26):9128-9134
The Lewis acid mediated domino "[3+3]-cyclization-homo-Michael" reaction of 1,3-bissilyl enol ethers with 1,1-diacylcyclopropanes allows an efficient one-pot synthesis of functionalized salicylates containing a halogenated side chain. A great variety of substitution patterns could be realized by variation of the starting materials and of the Lewis acid. The mechanism of the domino process was studied. 相似文献
2.
Nilofar Mustafa Naveed Iqbal Raja Noshin Ilyas Fozia Abasi Muhammad Sheeraz Ahmad Maria Ehsan Asma Mehak Imran Badshah Jarosaw Prokw 《Molecules (Basel, Switzerland)》2022,27(15)
Agriculture is the backbone of every developing country. Among various crops, wheat (Triticum aestivum L.) belongs to the family Poaceae and is the most important staple food crop of various countries. Different biotic (viruses, bacteria and fungi) and abiotic stresses (water logging, drought and salinity) adversely affect the qualitative and quantitative attributes of wheat. Among these stresses, salinity stress is a very important limiting factor affecting the morphological, physiological, biochemical attributes and grain yield of wheat. This research work was carried out to evaluate the influence of phytosynthesized TiO2 NPs on the germination, physiochemical, and yield attributes of wheat varieties in response to salinity. TiO2 NPs were synthesized using TiO2 salt and a Buddleja asiatica plant extract as a reducing and capping agent. Various concentrations of TiO2 nanoparticles (20, 40, 60 and 80 mg/L) and salt solutions (NaCl) (100 and 150 mM) were used. A total of 20 mg/L and 40 mg/L improve germination attributes, osmotic and water potential, carotenoid, total phenolic, and flavonoid content, soluble sugar and proteins, proline and amino acid content, superoxide dismutase activity, and reduce malondialdhehyde (MDA) content at both levels of salinity. These two concentrations also improved the yield attributes of wheat varieties at both salinity levels. The best results were observed at 40 mg/L of TiO2 NPs at both salinity levels. However, the highest concentrations (60 and 80 mg/L) of TiO2 NPs showed negative effects on germination, physiochemical and yield characteristics and causes stress in both wheat varieties under control irrigation conditions and salinity stress. Therefore, in conclusion, the findings of this research are that the foliar application of TiO2 NPs can help to improve tolerance against salinity stress in plants. 相似文献
3.
Muhammad Ali Ehsan Muhammad Adil Mansoor Muhammad Mazhar Asif Ali Tahir Mazhar Hamid K. G. Upul Wijayantha 《应用有机金属化学》2012,26(9):493-498
A single molecular heterobimetallic complex, [Co2Ti(μ3‐O)(TFA)6(THF)3] (1) [TFA = trifluoroacetate, THF = tetrahydrofuran], was synthesized, structurally and spectroscopically characterized and implemented as a single‐source precursor for the preparation of CoTiO3–CoO composite thin films by aerosol‐assisted chemical vapour deposition (AACVD). The precursor complex was prepared by interaction of Co(OAc)2.4H2O [OAc = (CH3COO?)] with Ti(iso‐propoxide)4 in the presence of trifluoroacetic acid in THF, and was analysed by melting point, CHN, FT‐IR, single‐crystal X‐ray diffraction and thermogravimetric analysis. The precursor complex thermally decomposed at 480 °C to give a residual mass corresponding to a CoTiO3–CoO composite material. Good‐quality crystalline CoTiO3–CoO composite thin films deposited at 500 °C by AACVD and characterized through powder X‐ray diffraction and scanning electron microscopy/energy‐dispersive X‐ray spectroscopy show that the crystallites have a rose‐flower‐like morphology with an average petal size in the range of 2–6 µm. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
4.
Benjamin Arras Ehsan Azmoodeh Guillaume Poly Yvik Swan 《Stochastic Processes and their Applications》2019,129(7):2341-2375
We provide a bound on a distance between finitely supported elements and general elements of the unit sphere of . We use this bound to estimate the Wasserstein-2 distance between random variables represented by linear combinations of independent random variables. Our results are expressed in terms of a discrepancy measure related to Nourdin–Peccati’s Malliavin–Stein method. The main application is towards the computation of quantitative rates of convergence to elements of the second Wiener chaos. In particular, we explicit these rates for non-central asymptotic of sequences of quadratic forms and the behavior of the generalized Rosenblatt process at extreme critical exponent. 相似文献
5.
We present a biographical sketch of Alenush Terian, the first Iranian woman physicist, who was known as the Iranian Solar Mother, since she founded the first solar telescopic observatory in Iran. She taught and carried out astronomical research for three decades with inadequate resources but with unflinching devotion, motivated by a strong desire to propagate scientific education and research in her country. 相似文献
6.
7.
Ahmad Seif Ehsan Zahedi Goodarz M. Rozbahani 《Central European Journal of Chemistry》2012,10(1):96-104
To investigate the influence of C-doping on the electrostatic structure properties in the frame work of density functional
theory (DFT), we considered beryllium monoxide nanotubes (BeONTs), consisting of 60 Be and 60 O atoms. Full geometry optimizations
are performed for all structures, i.e., all atoms are allowed to relax. Afterwards, the chemical shielding (CS) tensors are
calculated for Be-9, O-17 and C-13 nuclei in the C-doped forms and also pristine models of the (10, 0) zigzag and (5, 5) armchair
BeONTs. Formation energies indicate that C-doping of Be atom (CBe form) could be more favorable than C-doping of O atom (CO
form) in both zigzag and armchair BeONTs. Gap energies and dipole moments detected the effects of dopant in the (5, 5) armchair
models; however, those parameters did not indicate any significant changes in the C-doped (10, 0) zigzag BeONT models. The
results show that the CS values for the Be and O atoms-contributed to the Be-C bonds or those atoms close to the C-doped region-in
the CO form of BeONTs (zigzag and armchair) are changed. The same values only for the O atoms-contributed to the O-C bonds-
in the CBe form of BeONTs (zigzag and armchair) are changed. 相似文献
8.
Alireza Hasaninejad Khodabakhsh Niknam Abdolkarim Zare Ehsan Farsimadan Mohsen Shekouhy 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1):147-155
Silphox [POCl3-n(SiO2)n] efficiently catalyzes the condensation of benzene-1,2-diamine with mono and dicarboxylic acids under microwave irradiation to afford benzimidazole derivatives in high yields and short reaction times. 相似文献
9.
Mehdi Adib Ehsan Sheikhi Pouyan Haghshenas Saideh Rajai-Daryasarei Hamid Reza Bijanzadeh Long-Guan Zhu 《Tetrahedron letters》2014
A novel one-pot, five-component synthesis of 1-(alkylimino)-5,5-dicyano-3a-aryloctahydro-3-oxacyclobuta[cd]pentalene-1a,2,5a,5b(2H,3aH)-tetracarboxylates is described. A mixture of phenacyl bromide, malononitrile, isocyanide, and two equivalents of a dialkyl acetylenedicarboxylate undergoes a novel 1:1:1:2 addition reaction at ambient temperature in absolute ethanol to produce diastereoselectively the title compounds in good yields. 相似文献
10.
Sharifkhani Samira M. Yaftian Mohammad Reza Hosseini Majid Haji Zolfonoun Ehsan 《Journal of Analytical Chemistry》2022,77(4):505-512
Journal of Analytical Chemistry - In this study, for the first time, the organic gas steam-liquid extraction by a special hand-made cell was used as a simple and inexpensive preconcentration... 相似文献