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排序方式: 共有575条查询结果,搜索用时 9 毫秒
51.
Kiran Kumarvarma Chakrahari Rhone P. Brocha Silalahi Tzu‐Hao Chiu Xiaoping Wang Nadia Azrou Samia Kahlal Yu‐Chiao Liu Ming‐Hsi Chiang Jean‐Yves Saillard C. W. Liu 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(15):4997-5001
The structurally precise Cu‐rich hydride nanoclusters [PdCu14H2(dtc/dtp)6(C≡CPh)6] (dtc: di‐butyldithiocarbamate ( 1 ); dtp: di‐isopropyl dithiophosphate ( 2 )) were synthesized from the reaction of polyhydrido copper clusters [Cu28H15(S2CNnBu2)12]+ or [Cu20H11{S2P(OiPr)2}9] with phenyl acetylene in the presence of Pd(PPh3)2Cl2. Their structures and compositions were determined by single‐crystal X‐ray diffraction and the results supported by ESI‐mass spectrometry. Hydride positions in 1 were confirmed by single‐crystal neutron diffraction. Each hydride is connected to one Pd0 and four CuI atoms in slightly distorted trigonalbipyramidal geometry. The anatomies of clusters 1 and 2 are very similar and DFT calculations allow rationalizing the interactions between the encapsulated [PdH2]2? unit and its Cu14 bicapped icosahedral cage. As a result, Pd has the highest coordination number (14) so far recorded. 相似文献
52.
The ferroelectric ceramics Ba5RTi3V7O30 (R=Ho, Gd, La) have been synthesized by solid-state reaction technique. Preliminary X-ray structural analysis confirmed a single-phase formation of the compound in orthorhombic structure. Surface morphology of the compounds was studied by scanning electron microscopy (SEM). Detailed studies of electrical properties (i.e., dielectric constant, loss tangent, ac conductivity) as a function of temperature (RT-773 K) and at four different frequencies (1 kHz, 10 kHz, 100 kHz and 1 MHz) show ferroelectric–paraelectric phase transition of the compounds of diffuse-type. The activation energy has been evaluated from ac conductivity following Arrhenius equation. The conductivity pattern shows that it is strongly frequency dependent and obeys Jonscher's power relation. 相似文献
53.
Mauji Ram Salim Khan Prabhakar Jha Mather A. Khan Usha Kiran Saleem Javed Malik Z. Abdin 《Chromatographia》2008,68(1-2):129-133
A simple, rapid, specific and sensitive thin layer chromatographic (TLC) method has been developed for the quantitative estimation of mevalonic acid (MVA) in leaves of medicinal plants; Artemisia annua, Psorelia corylifolia, Vinca rosea, Withania somnifera and Barleria proinites. The assay procedure involved conversion of MVA to its lactone, mevalonolactone (MVAL). Mevalonic acid was extracted from the leaf tissues of plants. Separation of MVAL was carried out on silica gel 60 F254 TLC plates using benzene:acetone (3:2) as the mobile phase. The densitometric determination of MVAL was performed at 600 nm after derivatization with anisaldehyde reagent in absorption–reflectance mode. The method was validated over the linearity range of 100–500 ng spot?1 and correlation coefficient for the calibration curve was >0.99. The average recovery of MVAL, used as internal standard, was higher than 98%. The lower limit of detection was found to be 50 ng spot?1. 相似文献
54.
Jian-Jun Qin Maung Htun Oo Kiran A. Kekre Boris Liberman 《Journal of membrane science》2010,346(1):8-14
The objective of the study was to further develop a novel cleaning technique for reverse osmosis in reclamation of municipal secondary effluent. This technique is a new backwash method via direct osmosis (DO) by intermittent injection of the high salinity (HS) solution without stopping of high pressure pump and it is environment and membrane friendly technique. In the study, DO-HS trials were carried out with a UF-RO pilot system which was operated on site with the secondary treated effluent as the raw feed. Different operating conditions for DO-HS treatment in the actual process were investigated. It was found that the operation for implementation of the DO-HS cleaning technique developed was easy. For the first time, the actual profiles of HS concentration, DO backwash flow rate, brine flow rate and permeate pressure during DO-HS treatment have been demonstrated. It was observed that turbidity of the brine stream during DO-HS treatment at 3 NTU was 5 times higher than that before DO-HS treatment. The results from this study have confirmed the previous hypothesis with DO-HS treatment that there would be a strong driving force for DO backwash to lift and sweep the foulants from the membrane surface which would be carried over to the brine. The optimal plant operating conditions in terms of RO feed flow rate, HS concentration and HS injection time are ready for the DO-HS method to be adopted and validated in a long-term continuous plant operation. 相似文献
55.
Kiran Matcha 《Tetrahedron letters》2010,51(20):2754-6476
A concise synthesis of a highly functionalized tricyclic ring system representing the CDE core of nortriterpenoid schintrilactones A and B is described using a tandem ROM-RCM of a norbornene derivative. 相似文献
56.
A simple and efficient total synthesis of ellipticine was developed via the Suzuki-Miyaura coupling of sterically sensitive 2-hydroxybenzeneboronic acid with a multifunctional aryl halide using Pd(OAc)2 as a catalyst and Cu(OAc)2·H2O as an additive in DMSO/H2O as a key step followed by double N-arylation and cyclization. 相似文献
57.
Hosakere D Revanasiddappa Telangusadhushetty N Kiran Kumar 《Analytical sciences》2002,18(10):1131-1135
A simple, sensitive and rapid spectrophotometric method was developed for the determination of thallium(III) using trifluoperazine hydrochloride (TFPH). The method is based on the oxidation of TFPH by thallium(III) in a phosphoric acid medium to form a red-colored radical cation with an absorption maximum at 505 nm. Beer's law is valid over the concentration range of 0.5 - 6.5 microg ml(-1) of thallium(III). The molar absorptivity and Sandell's sensitivity of the color system are 2.14 x 10(4) l mol(-1) cm(-1) and 0.0095 microg cm(-2), respectively. The optimum reaction conditions and other analytical parameters were evaluated. The tolerance limit of the method towards various ions usually associated with thallium has been studied. The proposed method has been successfully applied to the analysis of thallium in alloys, minerals, standard reference material, water, and urine samples. 相似文献
58.
The effect of change in deuteron size on its elastic scattering from protons and alphas is investigated by varying the Hulthen
parameters of the deuteron wave function in the scattering process. The cross sections forp-d scattering, calculated in the Born approximation, are found to increase substantially at backward angles even when the deuteron
size is reduced by a small amount, whereas the shape of the angular distribution does not change significantly. For theα-d elastic scattering, interaction potential is obtained by folding the deuteron wave function and the optical potential for
nucleon-scattering. The cross sections calculated atE
d
= 13·7 MeV, shows that the first minimum around Θcm = 60° is deepend as the deuteron size is reduced, while at 52 MeV bombarding energy, the size effects are not very distinct.
These observations are useful in the interpretation of deuteron cluster knockout reactions. 相似文献
59.
Synthesis,Characterization, and Antibacterial Activity of Novel (1H‐Benzo[d]imidazole‐2‐yl)‐6‐(diethylamino)‐3H‐one‐xanthene,Phenoxazine, and Oxazine 下载免费PDF全文
Vikas S. Patil Vikas S. Padalkar Kiran R. Phatangare Prashant G. Umape Bhushan N. Borase N. Sekar 《Journal of heterocyclic chemistry》2015,52(1):124-129
A series of novel (1H‐benzo[d]imidazole‐2‐yl)‐6‐(diethylamino)‐3H‐one‐xanthene, phenoxazine, and oxazine derivatives have been synthesized from 2‐(2′,4′‐dihydroxyphenyl) benzimidazole intermediate. Synthesized compounds 8a , 8b , 8c , 8d are fluorescent in solution, photophysical properties of compounds were studied and results revealed that compounds absorb and emit in UV–visible region with good fluorescence quantum yield. Synthesized compounds are thermally stable up to 300°C. The antibacterial activities of the synthesized compounds were studied by the well‐diffusion method. Escherichia coli (ATTC‐25922), Staphylococcus aureus (ATCC‐25923), Micrococcus (ATCC‐4698), and Bacillus subtilis (ATCC‐55422) were used to investigate the antibacterial activities. 相似文献
60.
Madhava Golla Subba Rao Devineni Rasheed Syed Bhanu Kiran Rayalacheru Rajasekhar Maram 《Phosphorus, sulfur, and silicon and the related elements》2017,192(7):794-798
The synthesis of a new series of P-heterocyclic compounds, substituted 2-aminomethyl-2-oxo-2λ5-perhydro-[1,3,2]oxazaphospholo[3,4-a]pyridine derivatives 8(a-j), was accomplished. A key intermediate, 2-(chloromethyl)-2-oxo-2λ5-perhydro-[1,3,2]oxazaphospholo[3,4-a]pyridine (6) was primarily synthesized by the condensation of (±)-2-piperidinemethanol (4) and chloromethylphosphonic dichloride (5); subsequently, it was treated with various heterocyclic amines/benzylamines/aminoacid esters, 7(a-j) to obtain the desired products. The structures of the newly synthesized compounds were elucidated by 1H, 13C, and 31P NMR spectroscopy, mass spectra and elemental analyses. The biological potency of title products was investigated by screening in vitro antimicrobial activity. The bio-screening data revealed that most of the synthesized derivatives showed potent growth of inhibition against fungi while compared with bacteria. Particularly, compounds 8c and 8i against bacterial strains, and 8a and 8f against fungi exhibited promising activity. 相似文献