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91.
Konarev DV Zorina LV Khasanov SS Lyubovskaya RN 《Dalton transactions (Cambridge, England : 2003)》2012,41(30):9170-9175
Ionic complexes containing μ(2)-hydroxo-bonded (MgPc)(2)OH(-) phthalocyanine assemblies and C(60)(-) anions: {(MgPc)(2)OH(-)}(2)·(C(60)(-))(2)·(PMDAE(+))(4)·(C(6)H(5)CN)(4) (1); {(MgPc)(2)OH(-)}(2)·(C(60)(-))(2)·(TMP(+))(4)·(C(6)H(5)CN)(3)·(C(6)H(4)Cl(2))(2.5) (2) (where PMDAE(+) is the cation of N,N,N',N',N'-pentamethyldiaminoethane and TMP(+) is the N,N'N'-trimethylpiperazinium cation) have been obtained as single crystals. The ionic ground state of the complexes is justified by the EPR spectra and the spectra in the IR and NIR ranges. The C(60)˙(-) radical anions are dimerized both in 1 and 2 in the 240-220 K range. Dimerization is accompanied by the reversible transition of the complexes from paramagnetic to diamagnetic state. MgPc forms unusual (MgPc)(2)OH(-) assemblies, in which the hydroxo-anion coordinates to two MgPc molecules by a μ(2)-fashion. The length of the Mg-O bonds is 1.936-1.955(2) ?, the Mg-O-Mg angle is 133.37-135.27(4)° and the displacement of the Mg atoms out of the mean 24-atom phthalocyanine plane is 0.77-0.86 ?. The packing of spherical fullerene and planar phthalocyanine molecules is attained in a crystal by the insertion of fullerenes between phenylene groups of phthalocyanines. It has been shown that metal phthalocyanines in ionic complexes with C(60) form M(II)Pc·(L(-)) assemblies, whereas metalloporphyrins form M(II)porphyrin·(C(+)) assemblies. 相似文献
92.
Frontispiece: Synthesis,Structures, and Properties of Crystalline Salts with Radical Anions of Metal‐Containing and Metal‐Free Phthalocyanines 下载免费PDF全文
93.
E. F. Sheka B. S. Razbirin A. N. Starukhin D. K. Nelson M. Yu. Degunov R. N. Lyubovskaya P. A. Troshin 《Journal of Experimental and Theoretical Physics》2009,108(5):738-750
The “blue” emission from fullerene C60 and its derivatives in frozen toluene solution is discovered and analyzed in the framework of the electromagnetic theory of enhanced optical effects. It is shown that the emission, combining enhanced spectra of Raman scattering and one-photon luminescence, is due to clustering of fullerene molecules in solution. Photoexcitation of charge-transfer excitons in clusters provides the polarization required for the enhancement. A direct relationship is established between the observed phenomenon and nonlinear optical properties of the medium. Empirical and computational tests are proposed to select matrices with various nonlinear optical properties. 相似文献
94.
Metallic and Mott Insulating Spin‐Frustrated Antiferromagnetic States in Ionic Fullerene Complexes with a Two‐Dimensional Hexagonal C60.− Packing Motif 下载免费PDF全文
Dr. Dmitri V. Konarev Dr. Salavat S. Khasanov Dr. Akihiro Otsuka Dr. Mitsuhiko Maesato Dr. Mikio Uruichi Dr. Kyuya Yakushi Dr. Artem F. Shevchun Prof. Dr. Hideki Yamochi Prof. Dr. Gunzi Saito Prof. Rimma N. Lyubovskaya 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(24):7268-7277
(MDABCO+)(C60.?)(TPC) ( 1 ), in which MDABCO+ is N‐methyldiazabicyclooctanium, TPC is triptycene, and both have threefold symmetry, is a rare example of a fullerene‐based quasi‐2D metal and contains closely packed hexagonal fullerene layers with interfullerene center‐to‐center distances of 10.07 Å at 300 K. Evidence for the metallic nature of 1 was obtained by optical and microwave conductivity measurements on single crystals. The metal is characterized by a nontypical Drude response and relatively large optical mass (m*/m0=6.7). The latter indicates a narrow‐band nature, which is consistent with the calculated bandwidth of 0.10–0.15 eV. The coexistence of metallic and antiferromagnetic nonmetallic 2D layers was observed in 1 above 200–230 K. It was assumed that the nonmetallic layers undergo a transition to the metallic state below 200 K due to ordering of the fullerene and cationic sublattices. New layered complex (MQ+)(C60.?)(TPC) ( 2 ) with a hexagonal arrangement of C60.? was obtained by increasing the interfullerene distance with the bulkier N‐methylquinuclidinium cations (MQ+) having threefold symmetry. The structure of 2 is characterized by increased interfullerene center‐to‐center distances in the layers (10.124, 10.155, and 10.177 Å at 250 K). Unit‐cell doubling parallel to the 2D layer (along the b axis) was observed at low temperatures. In contrast to metallic 1 , 2 exhibits a nonmetallic spin‐frustrated state with an antiferromagnetic interaction of spins (the Weiss temperature is ?27 K) and no magnetic ordering down to 1.9 K. It was supposed that the expanded interfullerene distances in the triangular arrangement decrease the bandwidth and suppress metallic conductivity in 2 , and thus a Mott–Hubbard insulating state with antiferromagnetically frustrated spins results. 相似文献
95.
Strong Antiferromagnetic Coupling of Spins in the (MDABCO+)(C60.−) Salt with 3D Close Packing of the C60.− Radical Anions (MDABCO+: N‐Methyldiazabicyclooctanium Cation) 下载免费PDF全文
Dr. Dmitri V. Konarev Dr. Salavat S. Khasanov Dr. Akihiro Otsuka Prof. Hideki Yamochi Prof. Gunzi Saito Prof. Rimma N. Lyubovskaya 《化学:亚洲杂志》2014,9(6):1629-1635
A new salt, (MDABCO+)(C60.?) ( 1 ; MDABCO+=N‐methyldiazabicyclooctanium cation), was obtained as single crystals. The crystal structure of 1 determined at 250 and 100 K showed 3D close packing of fullerenes with eight fullerene neighbors for each C60.?. These neighbors are located at 10.01–10.11 Å center‐to‐center distances (250 K) and van der Waals interfullerene C???C contacts are formed with four fullerene neighbors arranged in the bc plane. Fullerene ordering observed below 160 K is accompanied by the appearance of one and a half independent C60.? and trebling of the unit cell along the b axis. Fullerenes are packed closer to each other at 100 K. As a result, fullerenes are located in the three‐dimensional packing at 9.91–10.12 Å center‐to‐center distances and 18 short interfullerene C???C contacts are formed for each C60.?. Although they are closed packed, fullerenes are not dimerized down to 1.9 K. Magnetic data indicate strong antiferromagnetic coupling of spins in the 70–300 K range with a Weiss temperature of Θ=?118 K. Magnetic susceptibility shows a round maximum at 46 K. Such behavior can be described well by the Heisenberg model for square two‐dimensional antiferromagnetic coupling of spins with an exchange interaction of J/kB=?25.3 K. This magnetic coupling is one of the strongest observed for C60.? salts. 相似文献
96.
R. M. Vlasova I. I. Reshina N. V. Drichko R. N. Lyubovskaya 《Physics of the Solid State》2000,42(8):1387-1393
The Raman and IR reflectivity spectra of the new organic metals (ET)8[Hg4X12(C6H5Y)2] (X, Y=Cl, Br) based on the molecule bis(ethylenedithio)tetrathiafulvalene (BEDT-TTF or ET in abbreviated form) have been investigated. These metals differ from the previously studied compounds, particularly, in the type of ET molecular packing in the quasi-two-dimensional conducting layers. A high reflectivity and a plasma minimum observed in the IR reflectivity spectrum indicate the presence of quasi-free charge carriers (holes), as in other conducting ET salts. However, the A g vibrational modes in the Raman spectrum are not activated in the IR spectrum, as is the case of conducting ET salts with other packing types. The Raman lines are assigned to the normal vibrations in the ET molecule, and their ionization shifts are determined. It is demonstrated that the frequencies of the most intense line ν3(A g) show a linear dependence on the cation charge, which is characteristic of different ET salts. No correlations are revealed between the ν3(A g) frequencies and the packing type. The strong background with a broad maximum at a Raman shift of about 3000 cm?1 is observed in the Raman spectra upon excitation with the 2.54-and 2.41-eV lines of an Ar+ laser. The assumption is made that such a background can be associated with the scattering by one-particle and collective electronic excitations. 相似文献
97.
98.
99.
I. B. Voskoboinikov S. V. Demishev R. N. Lyubovskaya V. V. Moshchalkov N. A. Samarin N. E. Sluchanko 《Physics of the Solid State》2002,44(2):210-215
This paper reports on measurements of the de Haas-van Alfven effect in the quasi-two-dimensional organic conductor (BEDT-TTF)8Hg4Cl12(C6H5Cl)2 performed within the temperature range 0.33–1.44 K in magnetic fields of B≤50 T. An analysis of quantum oscillations together with cyclotron resonance data obtained in the 40–120-GHz frequency range revealed that the complex quantum-oscillation spectrum is formed by the fundamental frequencies α~256 T and β~670–610 T, as well as by combination and multiple frequencies. It is shown that the character of the temperature-induced oscillation-spectrum rearrangement can be interpreted within a model taking into account the existence of a magnetic phase transition at T c~0.9 K and the closeness of the fundamental frequency α with effective mass m*=1.48m 0 to the spin damping condition. 相似文献
100.
R. M. Vlasova N. V. Drichko B. V. Petrov V. N. Semkin E. I. Zhilyaeva O. A. Bogdanova R. N. Lyubovskaya A. Graja 《Physics of the Solid State》2002,44(1):8-15
This paper reports on a study of the polarized reflectance and optical conductivity spectra of the quasi-two-dimensional molecular conductor θ-(BETS)4HgBr4(C6H5Cl) within the 700–6500-cm?1 region at 300–15 K and within the 9000–40 000 cm?1 region at 300 K performed along two principal directions in the crystal plane parallel to the conducting layers of the BETS molecules. The IR spectra obtained at 300 K follow a close-to-Drude behavior, with strong broad features (1200–1400 cm?1) due to electron-vibrational (vibronic) coupling (VC) superposed on the high Drude background. As the temperature is lowered in the range 180–80 K, in the spectra there appears a Lorentz term with ωt=2900 cm?1, as well as three additional VC-induced bands in the 800–1180-cm?1 region, which disappear as the temperature is decreased further. The results obtained indicate the existence of unstable structural distortions along the two principal directions in the crystal, which are accompanied by the formation of a commensurate charge-density wave. 相似文献