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101.
Stable nitroxide radicals are useful to construct molecular magnetic systems. Particularly, radicals substituted by –COOH and –CONH2 can be coordinated to magnetic metal ions and may be used as cladding reagents of gold nano-particles for modifying magnetism. Nitroxide molecules with unsaturated five-member ring have almost planner structure and electron spin delocalization may be expected. We determined the hyperfine coupling constants (hfcc) of 1H, 2H and 13C of a series of nitroxide radicals with five-member ring. Experimental values of hfcc were compared with those deduced from calculations based on density functional theory. The electron spin density distribution at β position of ring was sensitive to the ring structure, although the electron spin density at β position is small compared with N–O site. Magnetic susceptibility and UV–Vis absorption spectra were also measured and discussed. 相似文献
102.
Yuji Shibahara Yoko Akiyama Yoshinobu Izumi Shigehiro Nishijima Yoshihide Honda Norio Kimura Seiichi Tagawa Goro Isoyama 《Journal of Polymer Science.Polymer Physics》2008,46(1):1-7
The thermal degradation of Nafion membrane was analyzed with age‐momentum correlation (AMOC) measurement and four‐electrode AC impedance measurement. In the heated sample, the decrease in proton conductivity was observed. The lifetimes and corresponding relative intensities showed fairly good agreement between heated and nonheated samples within the experimental error. In the analysis of the photopeak of annihilation γ‐ray, on the other hand, the difference between those two kinds of samples was observed, and this difference was found to be caused by the annihilation of free positrons with low energy electrons by using AMOC method. The decrease in proton conductivity was caused by the low energy electrons, namely sulfonic radicals. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 1–7, 2008 相似文献
103.
104.
DK Rai G Beaucage EO Jonah DT Britton S Sukumaran S Chopra GG Gonfa M Härting 《The Journal of chemical physics》2012,137(4):044311
Nanomaterials with disordered, ramified structure are increasingly being used for applications where low cost and enhanced performance are desired. A particular example is the use in printed electronics of inorganic conducting and semiconducting nanoparticles. The electrical, as well as other physical properties depend on the arrangement and connectivity of the particles in such aggregate systems. Quantification of aggregate structure and development of structure∕property relationships is difficult and progress in the application of these materials in electronics has mainly been empirical. In this paper, a scaling model is used to parameterize the structure of printed electronic layers. This model has chiefly been applied to polymers but surprisingly it shows applicability to these nanolayers. Disordered structures of silicon nanoparticles forming aggregates are investigated using small angle x-ray scattering coupled with the scaling model. It is expected that predictions using these structural parameters can be made for electrical properties. The approach may have wide use in understanding and designing nano-aggregates for electronic devices. 相似文献
105.
106.
Eiichi Bannai Etsuko Bannai Masatake Hirao Masanori Sawa 《Journal of Algebraic Combinatorics》2012,35(1):109-119
In this paper we prove that there exists no minimum cubature formula of degree 4k and 4k+2 for Gaussian measure on ℝ2 supported by k+1 circles for any positive integer k, except for two formulas of degree 4. 相似文献
107.
The isomeric states and intermolecular packing of tris(8-hydroxyquinoline) aluminum(III) (Alq(3)) in the alpha-, gamma-, and delta-crystalline forms and in the amorphous state, which are important for understanding the light-emitting and electron-transport properties, have been analyzed by CP/MAS (13)C NMR. This simple NMR experiment shows that the isomeric state of alpha- and amorphous Alq(3) is meridional, whereas that of gamma- and delta-Alq(3) is facial. In the amorphous Alq(3), the inclusion of facial isomers has been under debate. Our experiments show that meridional isomers are dominant in the amorphous Alq(3), although the existence of facial isomers cannot be completely denied. The local structure of amorphous Alq(3) is similar to that of alpha-Alq(3) and is significantly different from those of gamma- and delta-Alq(3). Among these Alq(3) samples, the effect of intermolecular interaction is not found only for gamma-Alq(3). This finding can explain the good solvent solubility of gamma-Alq(3), compared with the other crystalline forms. It is also shown that the structures are locally disordered not only for amorphous Alq(3) but also for alpha-Alq(3), although clear X-ray diffraction peaks are observed for alpha-Alq(3). In contrast, the local structures of gamma- and delta-Alq(3) are well defined. A clear relation is found between the spectral patterns of CP/MAS (13)C NMR and the fluorescence wavelengths; the samples, which consist of facial isomers, show blue-shifted fluorescence compared with those of meridionals. 相似文献
108.
Takaishi S Kawakami D Yamashita M Sasaki M Kajiwara T Miyasaka H Sugiura K Wakabayashi Y Sawa H Matsuzaki H Kishida H Okamoto H Watanabe H Tanaka H Marumoto K Ito H Kuroda S 《Journal of the American Chemical Society》2006,128(19):6420-6425
We synthesized a novel iodo-bridged linear chain platinum compound, having the quasi-two-dimensional charge-density-wave (CDW) ground state and the smallest band gap. In this compound, we discovered an anomalous valence state in the boundary region at which the CDW phase alternates in the crystal by means of ESR, X-ray diffuse scattering, STM, and electrical resistivity. This anomalous state can be explained by the fast fluctuation between Pt(IV)-I...Pt(II) and Pt(II)...I-Pt(IV) in the double well potential. This is the first observation of the dynamical fluctuation of the CDW phase among the quasi one-dimensional halogen-bridged complexes. 相似文献
109.
110.
Dr. Yukihiro Yoshida Dr. Yasuhiro Shimizu Dr. Takeshi Yajima Dr. Goro Maruta Prof. Dr. Sadamu Takeda Dr. Yoshiaki Nakano Dr. Takaaki Hiramatsu Prof. Dr. Hiroshi Kageyama Prof. Dr. Hideki Yamochi Prof. Dr. Gunzi Saito 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(37):12313-12324
Ten types of neutral charge transfer (CT) complexes of coronene (electron donor; D) were obtained with various electron acceptors (A). In addition to the reported 7,7,8,8‐tetracyanoquinodimethane (TCNQ) complex of 1:1 stoichiometry with a DA‐type alternating π column, TCNQ also afforded a 3:1 complex, in which a face‐to‐face dimer of parallel coronenes ( Cor‐A s) is sandwiched between TCNQs to construct a DDA‐type alternating π column flanked by another coronene ( Cor‐B ). Whereas solid‐state 2H NMR spectra of the 1:1 TCNQ complex formed with deuterated coronene confirmed the single in‐plane 6‐fold flipping motion of the coronenes, two unsynchronized motions were confirmed for the 3:1 TCNQ complex, which is consistent with a crystallographic study. Neutral [Ni(mnt)2] (mnt: maleonitriledithiolate) as an electron acceptor afforded a 5:2 complex with a DDA‐type alternating π column flanked by another coronene, similar to the 3:1 TCNQ complex. The fact that the Cor‐A s in the [Ni(mnt)2] complex arrange in a non‐parallel fashion must cause the fast in‐plane rotation of Cor‐A relative to that of Cor‐B . This is in sharp contrast to the 3:1 TCNQ complex, in which the dimer of parallel Cor‐A s shows inter‐column interactions with neighboring Cor‐A s. The solid‐state 1H NMR signal of the [Ni(mnt)2] complex suddenly broadens at temperatures below approximately 60 K, indicating that the in‐plane rotation of the coronenes undergoes down to approximately 60 K; the rotational rate reaches the gigahertz regime at room temperature. Rotational barriers of these CT complexes, as estimated from variable‐temperature spin–lattice relaxation time (T1) experiments, are significantly lower than that of pristine coronene. The investigated structure–property relationships indicate that the complexation not only facilitates the molecular rotation of coronenes but also provides a new solid‐state rotor system that involves unsynchronized plural rotators. 相似文献