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71.
Shin-Ichi Shamoto Keigo Iizawa Yusuke Asano Kenji Ohoyama Tsuyoshi Kajitani 《Molecular Crystals and Liquid Crystals》2013,570(2):515-520
Abstract Superconducting critical temperature, Tc and the shielding volume fraction, SVF, of layered nitride superconductor NaxHfNCl have been studied as a function of x, i.e. Na concentration. Although Tc decreases gradually with increasing x from 20.0 K at x=0.11 to 16.5 K at x=0.85, SVF has a sharp peak around x=1/6, where strong coupling between local ordering of Na atoms and Fermi surface instability can be expected. Structural disorder in the samples above x=0.5, observed by powder neutron diffraction, does not affect the superconductivity appreciably. Electronic specific heat coefficient, γ, is estimated to be about 7.7 mJ/mol/K2 by its difference of magnetic susceptibility between HfNCl and Na0.5HfNCl. The γ value is relatively small compared with the high Tc value, revealing double honeycomb lattice system as new potential higher Tc superconductor series by intercalation. 相似文献
72.
Koji Kamagata Hiroyuki Tomiyama Yumiko Motoi Masayoshi Kano Osamu Abe Kenji Ito Keigo Shimoji Michimasa Suzuki Masaaki Hori Atsushi Nakanishi Ryohei Kuwatsuru Keisuke Sasai Shigeki Aoki Nobutaka Hattori 《Magnetic resonance imaging》2013
Objective
The pathological changes in Parkinson disease begin in the brainstem; reach the limbic system and ultimately spread to the cerebral cortex. In Parkinson disease (PD) patients, we evaluated the alteration of cingulate fibers, which comprise part of the limbic system, by using diffusional kurtosis imaging (DKI).Methods
Seventeen patients with PD and 15 age-matched healthy controls underwent DKI with a 3-T MR imager. Diffusion tensor tractography images of the anterior and posterior cingulum were generated. The mean kurtosis (MK) and conventional diffusion tensor parameters measured along the images in the anterior and posterior cingulum were compared between the groups. Receiver operating characteristic (ROC) analysis was also performed to compare the diagnostic abilities of the MK and conventional diffusion tensor parameters.Results
The MK and fractional anisotropy (FA) in the anterior cingulum were significantly lower in PD patients than in healthy controls. The area under the ROC curve was 0.912 for MK and 0.747 for FA in the anterior cingulum. MK in the anterior cingulum had the best diagnostic performance (mean cutoff, 0.967; sensitivity, 0.87; specificity, 0.94).Conclusions
DKI can detect alterations of the anterior cingulum in PD patients more sensitively than can conventional diffusion tensor imaging. Use of DKI can be expected to improve the ability to diagnose PD. 相似文献73.
This paper formulates a random-growth urban model with a notion of geographical fitness. Using techniques of complex-network theory, we study our system as a type of preferential-attachment model with fitness, and we analyze its macro behavior to clarify the properties of the city-size distributions it predicts. First, restricting the geographical fitness to take positive values and using a continuum approach, we show that the city-size distributions predicted by our model asymptotically approach Pareto distributions with coefficients greater than unity. Then, allowing the geographical fitness to take negative values, we perform local coefficient analysis to show that the predicted city-size distributions can deviate from Pareto distributions, as is often observed in actual city-size distributions. As a result, the model we propose can generate a generic class of city-size distributions, including but not limited to Pareto distributions. For applications to city-population projections, our simple model requires randomness only when new cities are created, not during their subsequent growth. This property leads to smooth trajectories of city population growth, in contrast to other models using Gibrat’s law. In addition, a discrete form of our dynamical equations can be used to estimate past city populations based on present-day data; this fact allows quantitative assessment of the performance of our model. Further study is needed to determine appropriate formulas for the geographical fitness. 相似文献
74.
Noriyoshi Matsumi Mari Miyamoto Keigo Aoi 《Journal of organometallic chemistry》2009,694(11):1612-10648
In the present study, a novel ionic liquid including o-carborane anion was prepared. After the carbene formation of 1-ethyl-3-methylimidazolium halide ([EMIm]+[X]−) by reaction with n-BuLi, the subsequent reaction with o-carborane afforded the desired ionic liquid in moderate yields. The structure of the ionic liquid was supported by 1H NMR and 11B NMR spectra. 相似文献
75.
Aleksandra Deptuch Teresa Jaworska-Gołąb Monika Marzec Jakub Fitas Keigo Nagao Janusz Chruściel 《Phase Transitions》2017,90(8):765-772
ABSTRACTProperties of 4-n-pentylphenyl-4’-n-octyloxythiobenzoate (8OS5), belonging to the nOS5 homologous series, have been studied by complementary methods. The phase sequence, the phase transition temperatures, the thickness of molecular layers, the average distance between long axes of molecules and the correlation length were determined during cooling and heating. For the first time, simultaneous X-ray diffraction and differential scanning calorimetry measurements have been used to study mesomorphic properties. The results are compared with the ones obtained in standard measurements by means of differential scanning calorimetry, X-ray diffraction and polarizing optical microscopy. Meaning of experimental procedures applied in investigations of monotropic mesophases below a melting point is discussed. 相似文献
76.
A novel non-contact fiber optic accelerometer is presented. Two laser beams that have passed through two different lengths of feed fibers are launched to the same moving target. The frequency of each beam is Doppler shifted by movement of the target. The frequency shift of the laser beam corresponds to the velocity of the target at the time of launch. The difference in launching time due to the difference in feed fiber lengths samples the velocities of the target at times spaced by the differential arrival times of the laser beams. Two return passes of the reflected light are also made different so that the light passed through the shorter feed fiber is steered to the longer return fiber by means of a combination of A/4 plate and polarization beam splitter (PBS). This arrangement of equalizing the total paths relieved a stringent requirement of the coherency of the laser. Two reflected light beams are mixed and the beat frequency corresponds to the difference in the Doppler shift frequency at two different times of arrival of the launcher. An accelerometer based upon this principle was constructed and its performance was examined using a sinusoidally vibrating hydrophone as a target. Features of such an accelerometer are reduction in the coherency requirements of the light source and simpler amplification of the signal using heterodyne detection.On leave of absence from Department of Optical Engineering, Zhejiang University, HangZhou, China 310027 相似文献
77.
Masahiko Okada Yasunari Okada Keigo Aoi 《Journal of polymer science. Part A, Polymer chemistry》1995,33(16):2813-2820
Six different polyesters ( 6a–6c and 7a–7c ) were prepared by the bulk polycondensations of the respective combinations of 1,4:3,6-dianhydro-D-glucitol ( 3 ) and 1,4:3,6-dianhydro-D-mannitol ( 4 ) with succinyl dichloride ( 5a ), glutaryl dichloride ( 5b ), and adipoyl dichloride ( 5c ) at 140–180°C. Polyesters having number average molecular weights up to 2.6 ×104 were obtained in high yields. Only polyester 7a based on 4 and 5a was partially crystalline, whereas all the other polyesters were amorphous. Thin films of these polyesters except that of 7a were spontancously hydrolyzed in a neutral phosphate buffer solution at 50°C, whereas they were reluctant to be hydrolyzed at 27°C. The polyesters were more or less degraded at 27°C by treatment with an activated sludge or by prolonged burial in soil. © 1995 John Wiley & Sons, Inc. 相似文献
78.
Optically active disilanes with one chiral silicon center, (R)-1,2-dimethyl-1-(naphth-1-yl)-1,2,2-triphenyldisilane and (R)-1,2,2-trimethyl-2-(4-methoxynaphth-1-yl)-1-(naphth-1-yl)-1-phenyldisilane, were obtained by the reaction of (S)-methyl(naphth-1-yl)phenylchlorosilane (> 99% ee) with methyldiphenylsilyllithium or by the reaction of methyldiphenylchlorosilane with optically active (S)-methyl(naphth-1-yl)phenylsilyllithium and by the reaction of (S)-methyl(naphth-1-yl)phenylchlorosilane (> 99% ee) with dimethyl(4-methoxynaphth-1-yl)silyllithium. Under the optimized conditions, the reactions proceeded with almost complete inversion for the cholorosilanes and retention for the silyl anions. Optically active disilanes with two chiral centers, (1R,2R)-1,2-dimethyl-1,2-di(naphth-1-yl)-1,2-diphenyldisilane and (1S,2S)-1,2-di(4-methoxynaphth-1-yl)-1,2-dimethyl-1,2-diphenyldisilane, were obtained in high optical purity by the reactions of corresponding optically active halogenosilanes (Cl or F) with optically active silyllithiums. The silicon-silicon bond and the silicon-naphthyl bond of (R)-1,1,2-trimethyl-1,2-di(naphth-1-yl)-2-phenyldisilane and (1R,2R)-1,2-dimethyl-1,2-di(naphth-1-yl)-1,2-diphenyldisilane were cleaved without selectivity on bromination. The silicon-(4-methoxynaphth-1-yl) bond of (R)-1,2,2-trimethyl-2-(4-methoxynaphth-1-yl)-1-(naphth-1-yl)-1-phenyldisilane was regiospecifically cleaved, followed by the stereoselective cleavage of the remaining chiral silicon-naphthyl bond (94% inversion). Although the silicon-(4-methoxynaphth-1-yl) bonds of (1S,2S)-1,2-di(4-methoxynaphth-1-yl)-1,2-dimethyl-1,2-diphenyldisilane (> 99% ee) were regioselectively cleaved without silicon-silicon bond scission, remarkable racemization could not be avoided during the one-pot reaction. 相似文献
79.
80.
Rho-kinase is a leading player in the regulation of cytoskeletal events involving smooth muscle contraction and neurite growth-cone
collapse and retraction, and is a promising drug target in the treatment of both vascular and neurological disorders. Recent
crystal structure of Rho-kinase complexed with a small-molecule inhibitor fasudil has revealed structural details of the ATP-binding
site, which represents the target site for the inhibitor, and showed that the conserved phenylalanine on the P-loop occupies
the pocket, resulting in an increase of protein–ligand contacts. Thus, the P-loop pliability is considered to play an important
role in inhibitor binding affinity and specificity. In this study, we carried out a molecular dynamic simulation for Rho-kinase–fasudil
complexes with two different P-loop conformations, i.e., the extended and folded conformations, in order to understand the
P-loop pliability and dynamics at atomic level. A PKA–fasudil complex was also used for comparison. In the MD simulation,
the flip-flop movement of the P-loop conformation starting either from the extended or folded conformation was not able to
be observed. However, a significant conformational change in a long loop region covering over the P-loop, and also alteration
of ionic interaction-manner of fasudil with acidic residues in the ATP binding site were shown only in the Rho-kinase–fasudil
complex with the extended P-loop conformation, while Rho-kinase with the folded P-loop conformation and PKA complexes did
not show large fluctuations, suggesting that the Rho-kinase–fasudil complex with the extended P-loop conformation represents
a meta-stable state. The information of the P-loop pliability at atomic level obtained in this study could provide valuable
clues to designing potent and/or selective inhibitors for Rho-kinase.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献