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501.
Herein we report a silver-catalyzed ring-opening of cyclopropenes by addition of amines. This transformation is thought to occur via an argentocarbenium intermediate and affords tertiary α-branched allylic amines in good yields and high regioselectivity. The protocol applies to various primary and secondary amines, as well as sterically hindered cyclopropenes. Friedel–Crafts cyclization of the cationic intermediate occurs as a competitive pathway to form methyl-indene. 相似文献
502.
Nguyen Hoa Hong A. T. Raghavender O. Ciftja M.-H. Phan K. Stojak H. Srikanth Yin Hua Zhang 《Applied Physics A: Materials Science & Processing》2013,112(2):323-327
Normally, CoFe2O4 has been known as ferromagnetic ferrite with a quite large magnetic moment. However, since we aim to inject the particles into the human body, we are also interested in ZnFe2O4 because in the human body, Fe and Zn exist, so that adding ZnFe2O4 is safer. In both cases, the nanoparticles are coated by silica in order to get rid of toxicity. Our main purpose is to test whether these nanoparticles affect the contractile function of heart cells. Our results on rat’s heart cells have shown that both Zn and Co ferrites improved the contractility of heart cells. Notably, although both nanoparticles increased contraction and delayed relaxation, Co ferrites induced a greater contraction but with a slower relaxation. We can theoretically argue that the magnetization effects of the quantum dots have a considerable effect on the pulsating properties of the heart cells. Through this effect, the locally applied magnetic field is able to induce as well as turn on/off various regular beating patterns, thus, resetting the heart beatings. 相似文献
503.
504.
C. Gautherin M. Houry W. Korten Y. Le Coz R. Lucas X.H. Phan C. Theisen C. Badimon G. Barreau T.P. Doan G. Pedemay G. Bélier M. Girod V. Méot S. Peru A. Astier L. Ducroux M. Meyer N. Redon 《The European Physical Journal A - Hadrons and Nuclei》1998,1(4):391-397
Isomeric states have been observed in fission-fragments produced by spontaneous fission of 252Cf. These states are found in neutron rich nuclei of different structure and deformations. About 50 isomeric nuclei have been
observed using coincidences between γ-rays identified in EUROGAM II and fission fragments detected in photovoltaic cells (SAPhIR).
Lifetimes in the range from 20 ns to 2μs have been measured. Presented calculations based on HFB +D1S force on new measured
isomeric states in the 152,154,156Nd show evidence for K-isomers.
Received: 3 November 1997 / Revised version: 15 December 1997 相似文献
505.
506.
Conclusions 1. Peregrinol and two new diterpenoids—marrubiol and vulgarol—have been isolated from the plantMarrubium vulgare L. for the first time.2. The structure of marrubiol (I), which is possibly a biogenetic precursor of marrubiin, has been demonstrated.Khimiya Prirodnykh Soedinenii, Vol. 4, No. 6, pp. 345–348, 1968 相似文献
507.
Temperature-dependent c-axis resistivity measurements on stages 1–7 potassium-graphite compounds show a crossover from metallic to activated behaviour between stages 4 and 5, as well as the onset of a new type of anomaly for stage ≥4. KC8 shows in addition a tendency toward a metal-insulator transition below 40K. The high-stage transport process is discussed in terms of weak depletion of the interior layers by interlayer screening. We suggest that the high stage anomalies reflect an instability in the c-axis charge distribution. 相似文献
508.
Tran Duc Thiep Truong Thi An Phan Viet Cuong Nguyen The Vinh A. G. Belov 《Journal of Radioanalytical and Nuclear Chemistry》2011,290(2):515-524
We have determined the isomeric ratios in 165Ho(γ, n)164m,gHo and 175Lu(γ, n)174m,gLu photonuclear reactions of natural holmium and lutetium induced by bremsstrahlungs with end-point energies in the giant
dipole resonance (GDR) region. The investigated samples were irradiated at electron accelerator Microtron MT-25 of the Flerov
Laboratory of Nuclear Reaction, Joint Institute for Nuclear Research, Dubna, Russia. The gamma spectra of the samples irradiated
were measured with spectroscopic system consisting of 8192 channel analyzer and high-energy resolution (180 keV at gamma ray
1332 keV of 60Co) HP(Ge) semiconductor detector Canberra. The GENIE2000 (Canberra) computer program was used for data processing. The results
were discussed and compared with those of other authors. 相似文献
509.
510.