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271.
Takaishi S Wu H Kajiwara T Breedlove BK Miyasaka H Yamashita M 《Dalton transactions (Cambridge, England : 2003)》2011,40(10):2160-2162
In STM images of [Pd(chxn-d(4))(2)Br]Br(2), which is in a quasi-2D-CDW state, we observed domain wall migration due to fast soliton motion at neighboring chains to the domain wall. 相似文献
272.
Miyasaka H Motokawa N Atsuumi R Kamo H Asai Y Yamashita M 《Dalton transactions (Cambridge, England : 2003)》2011,40(3):673-682
A series of paddlewheel diruthenium(ii, ii) complexes with various fluorine-substituted benzoate ligands were isolated as THF adducts and structurally characterized: [Ru(2)(F(x)PhCO(2))(4)(THF)(2)] (F(x)PhCO(2)(-) = o-fluorobenzoate, o-F; m-fluorobenzoate, m-F; p-fluorobenzoate, p-F; 2,6-difluorobenzoate, 2,6-F(2); 3,4-difluorobenzoate, 3,4-F(2); 3,5-difluorobenzoate, 3,5-F(2); 2,3,4-trifluorobenzoate, 2,3,4-F(3); 2,3,6-trifluorobenzoate, 2,3,6-F(3); 2,4,5-trifluorobenzoate, 2,4,5-F(3); 2,4,6-trifluorobenzoate, 2,4,6-F(3); 3,4,5-trifluorobenzoate, 3,4,5-F(3); 2,3,4,5-tetrafluorobenzoate, 2,3,4,5-F(4); 2,3,5,6-tetrafluorobenzoate, 2,3,5,6-F(4); pentafluorobenzoate, F(5)). By adding fluorine atoms on the benzoate ligands, it was possible to tune the redox potential (E(1/2)) for [Ru(2)(II,II)]/[Ru(2)(II,III)](+) over a wide range of potentials from -40 mV to 350 mV (vs. Ag/Ag(+) in THF). 2,3,6-F(3), 2,3,4,5-F(4), 2,3,5,6-F(4) and F(5) were relatively air-stable compounds even though they are [Ru(2)(II,II)] species. The redox potential in THF was dependent on an electronic effect rather than on a structural (steric) effect of the o-F atoms, although more than one substituent in the m- and p-positions shifted E(1/2) to higher potentials in relation to the general Hammett equation. A quasi-Hammett parameter for an o-F atom (σ(o)) was estimated to be ~0.2, and a plot of E(1/2)vs. a sum of Hammett parameters including σ(o) was linear. In addition, the HOMO energy levels, which was calculated based on atomic coordinates of solid-state structures, as well as the redox potential were affected by adding F atoms. Nevertheless, a steric contribution stabilizing their static structures in the solid state was present in addition to the electronic effect. On the basis of the electronic effect, the redox potential of these complexes is correlated to the HOMO energy level, and the electronic effect of F atoms is the main factor controlling the ionization potential of the complexes with ligands free from the rotational constraint, i.e. complexes in solution. 相似文献
273.
Three-pulse photon echo peak shift (3PEPS) measurement was applied to the investigation of the primary part (<100 ps) of the solvation dynamics in a series of imidazolium ionic liquids (IL) with an organic dye, oxazine 4 (Ox4), utilized as a probe. The ultrafast solvent response in the range of ≤300 fs exhibited dependence on the square root of the anion mass, indicating its relation with the inertial motion of anion. The inertial response of ILs with chloride anion was the fastest among other ILs with heavier and larger anions. Because Ox4 is a cationic dye, it holds a stronger interaction with the anion of IL, thus the ultrafast part of the solvation is strongly affected by the inertial motion of anions. The second solvation component in the range of ≤3.5 ps had better correlation with the reduced mass and the size of both ions included, indicating the beginning of a more global solvation process. 相似文献
274.
Hashikawa A Fujimoto M Hayashi Y Miyasaka H 《Chemical communications (Cambridge, England)》2011,47(45):12361-12363
A polyoxotetradecamolybdate cluster [Mo(14)O(38)(OAc)(6)](2-), which has a lacunary core of the Wells-Dawson structure, is isolated by the reduction of [Mo(6)O(19)](2-). The Mo(14) core is comprised of a mixed valence of [Mo(V)(4)Mo(VI)(10)], exhibiting multi-step reversible redox processes that experience both oxidation and reduction. 相似文献
275.
Yasuaki Tokudome Akira Miyasaka Kazuki Nakanishi Teiichi Hanada 《Journal of Sol-Gel Science and Technology》2011,57(3):269-278
Starting from calcium chloride dihydrate (CaCl2·2H2O), phosphoric acid (H3PO4), and poly(acrylic acid) (PAA) dissolved in a mixture of water and methanol (MeOH), dicalcium phosphate anhydrous (DCPA,
CaHPO4) monoliths with co-continuous macropores and mesopores have been synthesized by the addition of propylene oxide. Macropores
are formed as a result of phase separation, while mesopores as interstices between primary particles with the size of ca.
30 nm. Propylene oxide acts as a proton scavenger and leads to moderate pH increase in a reaction solution, which brings about
gelation in several minutes. On the other hand, PAA acts as a crystal growth inhibitor as well as a phase separation inducer.
The extensive crystal growth of DCPA is hindered by the addition of PAA which allows morphological control of the structure
in micrometer range. Fourier transform infrared spectroscopy indicates that PAA and DCPA form composite via interaction between
the carboxyl groups and the surface of crystals, and together form gel phase. The solvent phase, which is converted to macropores
after evaporative drying, is mainly comprised of solvent. The degree of supersaturation in a reaction solution considerably
influence on the crystallization process, and thereby, influences on the porous structure in nano- and micrometer ranges. 相似文献
276.
Wuttikul C Taoka T Akashi T Nakagawa H Miyasaka T Sakamoto M Takayama K Wada T Kitano S Takahama J Marugami N Kichikawa K 《Magnetic resonance imaging》2008,26(10):1374-1380
Purpose
This study discusses prominent signal intensity of T1/T2 prolongation of subcortical white matter within the anterior temporal region in premature infant brains that radiologists may encounter when interpreting conventional screening MRIs.Materials and Methods
T1- and T2-weighted images of 69 preterm and term infants with no neurological abnormalities or developmental delays were evaluated retrospectively for areas of prominent signal intensity of T1/T2 prolongation in white matter. We measured signal intensities of anterior temporal white matter, deep temporal white matter, frontopolar white matter and subcortical white matter of the precentral gyrus. We accessed chronological changes in signal intensity in the anterior and deep temporal white matter. We also analyzed variance tests among the signal intensity ratios to the ipsilateral thalamus of white matter areas by gestational age.Results
There was high frequency of prominent signal intensity of T1/T2 prolongation in the temporal tip, particularly at a gestational age of 36–38 weeks. Signal intensity ratio of the anterior temporal white matter was lower on T1-weighted images and higher on T2-weighted images, and the finding became less prominent with increasing gestational age. The signal intensity ratios of anterior temporal white matter at a gestational age of 36–37 weeks and 38–39 weeks were significantly different from other regions.Conclusion
Prominent signal intensity of T1/T2 prolongation of subcortical white matter of the anterior temporal region is seen in normal premature infants, especially those at 36–39 gestational weeks. Although it is a prominent finding, radiologists should understand that these findings do not represent a pathological condition. 相似文献277.
Hanasaki N Sano K Onose Y Ohtsuka T Iguchi S Kézsmárki I Miyasaka S Onoda S Nagaosa N Tokura Y 《Physical review letters》2008,100(10):106601
The transverse thermoelectric (Nernst) effect on pyrochlore molybdates is investigated experimentally. In Nd(2)Mo(2)O(7) and Sm(2)Mo(2)O(7) with the spin chirality, the Nernst signal, which mostly arises from the transverse heat current (or equivalently the transverse Peltier coefficient alpha(xy)), shows a low-temperature (20-30 K) positive extremum, whereas it is absent in (Gd(0.95)Ca(0.05))(2)Mo(2)O(7) with no single-spin anisotropy of the rare-earth ion and hence with no spin chirality. The correlation between the Hall conductivity sigma(xy) and alpha(xy) in Nd(2)Mo(2)O(7) also indicates the spin chirality plays a significant role in the spontaneous (anomalous) Nernst effect. 相似文献
278.
M. Reehuis C. Ulrich P. Pattison M. Miyasaka Y. Tokura B. Keimer 《The European Physical Journal B - Condensed Matter and Complex Systems》2008,64(1):27-34
The crystal structure and the magnetic ordering pattern of the electrically insulating perovskite CeVO3 was investigated by high-resolution powder X-ray diffraction and single-crystal neutron diffraction. A structural phase transition
from an orthorhombic to a monoclinic structure (with space groups Pbnm and P21/b, respectively) was observed upon cooling below T
s = 136 K. This transition is associated with a strong distortion of the VO6-octahedra and can be attributed to orbital ordering. A magnetic ordering transition driven by exchange interactions between
vanadium moments is observed at T
N = 124 K, and antiferromagnetic interactions between magnetic moments on vanadium and cerium ions induce a progressive magnetic
polarization of the cerium sublattice at lower temperatures. The full magnetic structure is described by a superposition of
the modes (C
x
, F
y
, −) and (F
x
, C
y
, −). The unit cell volume and the tilt angles of the VO6-octahedra in the CeVO3-crystal structure are anomalous compared to those of other members of the series RVO3 (R = lanthanide atom), and the ordered magnetic moments on both vanadium and cerium sublattices at low temperatures are considerably
smaller than the free-ion values of V3+ and Ce3+. Possible origins of this behavior are discussed. 相似文献
279.
Dr. Wataru Kosaka Yoshie Hiwatashi Naoka Amamizu Prof. Dr. Yasutaka Kitagawa Prof. Dr. Jun Zhang Prof. Dr. Hitoshi Miyasaka 《Angewandte Chemie (International ed. in English)》2023,62(48):e202312205
Partial charge fluctuations in the charge-ordered state of a material, often triggered by structural disorders and/or defects, can significantly alter its physical characteristics, such as magnetic long-range ordering. However, it is difficult to post-chemically fix such accidental partial fluctuations to reconstruct a uniform charge-ordered state. Herein, we report CO2-aided charge ordering demonstrated in a CO2-post-captured layered magnet, [{Ru2(o-ClPhCO2)4}2{TCNQ(OMe)2}] ⋅ CO2 ( 1⊃CO2 ; o-ClPhCO2−=ortho-chlorobenzoate; TNCQ(OMe)2=2,5-dimethoxy-7,7,8,8-tetracyanoquinodimethane). Pristine porous layered magnet 1 had a partially charge-fluctuated ordered state, which provided ferrimagnetic ordering at TC=65 K. Upon loading CO2, 1 adsorbed one mole of CO2, forming 1⊃CO2 , and raising TC to 100 K. This was because of the vanishing charge fluctuations without significantly changing the framework structure. This research illustrates the post-accessible host–guest chemistry delicately combined with charge, spin, and lattice ordering in a spongy magnet. Furthermore, it highlights how this innovative approach opens up new possibilities for technology and nanoscale magnetism manipulation. 相似文献