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排序方式: 共有347条查询结果,搜索用时 46 毫秒
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Dr. Emiko Kazuma Minhui Lee Prof. Jaehoon Jung Prof. Michael Trenary Dr. Yousoo Kim 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(20):8034-8040
Chemical reactions induced by plasmons achieve effective solar-to-chemical energy conversion. However, the mechanism of these reactions, which generate a strong electric field, hot carriers, and heat through the excitation and decay processes, is still controversial. In addition, it is not fully understood which factor governs the mechanism. To obtain mechanistic knowledge, we investigated the plasmon-induced dissociation of a single-molecule strongly chemisorbed on a metal surface, two O2 species chemisorbed on Ag(110) with different orientations and electronic structures, using a scanning tunneling microscope (STM) combined with light irradiation at 5 K. A combination of quantitative analysis by the STM and density functional theory calculations revealed that the hot carriers are transferred to the antibonding (π*) orbitals of O2 strongly hybridized with the metal states and that the dominant pathway and reaction yield are determined by the electronic structures formed by the molecule–metal chemical interaction. 相似文献
23.
Emiko Kazuma Minhui Lee Jaehoon Jung Michael Trenary Yousoo Kim 《Angewandte Chemie (International ed. in English)》2020,59(20):7960-7966
Chemical reactions induced by plasmons achieve effective solar‐to‐chemical energy conversion. However, the mechanism of these reactions, which generate a strong electric field, hot carriers, and heat through the excitation and decay processes, is still controversial. In addition, it is not fully understood which factor governs the mechanism. To obtain mechanistic knowledge, we investigated the plasmon‐induced dissociation of a single‐molecule strongly chemisorbed on a metal surface, two O2 species chemisorbed on Ag(110) with different orientations and electronic structures, using a scanning tunneling microscope (STM) combined with light irradiation at 5 K. A combination of quantitative analysis by the STM and density functional theory calculations revealed that the hot carriers are transferred to the antibonding (π*) orbitals of O2 strongly hybridized with the metal states and that the dominant pathway and reaction yield are determined by the electronic structures formed by the molecule–metal chemical interaction. 相似文献
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Naoyoshi Komatsu Keiko Masumoto Hidemitsu Aoki Chiharu Kimura Takashi Sugino 《Applied Surface Science》2010,256(6):1803-8310
Synthesis of Si-added aluminum oxide (AlSiO) films is attempted as an insulating film with both a wide bandgap and a high dielectric constant. Electrical characteristics of AlSiO films are investigated. Leakage current of the AlO film is suppressed by Si addition and is minimized with Si composition ratio of 12%. Capacitance versus voltage (C-V) measurements are carried out for Au/AlSiO/Si MIS structure. Both flat band shift and hysteresis of the C-V characteristics are suppressed by Si addition. A low leakage current is demonstrated for Au/AlSiO/n-SiC MIS structure. 相似文献
26.
描述了如何使用蒙特卡罗方法评估产生在加速器屏蔽混凝土中的感生放射性. 使用EGS4程序模拟了NaI闪烁探测器测量屏蔽混凝土块表面剂量率时, 对于半径和厚度的响应. 结果发现,在屏蔽混凝土块半径和厚度分别达到40cm和30cm时, 表面剂量率达到饱和. 研究了东京大学SF回旋加速器北墙位置8和位置9的表面剂量率, 并和使用NaI闪烁探测器的测量结果进行了对比, 发现模拟和实验结果符合很好. 并且, 获得了表面剂量和表面感生放射性之间的转换系数, 对于60Co转换系数为0.90(Bq·g-1)·(μSv·h-1)-1, 对于152Eu转换系数为1.26(Bq·g-1)·(μSv·h-1)-1. 这样, 就可以通过NaI闪烁探测器表面剂量的测量结果简单评估加速器设备屏蔽混凝土中的感生放射性. 相似文献
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Aliakbar Dehno Khalaji Gholamhossein Grivani Samaneh Jalali Akerdi Kazuma Gotoh Hiroyuki Ishida Hossein Mighani 《Structural chemistry》2010,21(5):995-1003
Two thiosemicarbazones, (E)-2-(2,4-dimethoxybenzylidene)thiosemicarbazone (24-MBTSC (1)) and (E)-2-(2,5-dimethoxybenzylidene)thiosemicarbazone (25-MBTSC (2)), derived from 2,4-dimethoxybenzaldehyde and 2,5-dimethoxybenzaldehyde, respectively, with thiosemicarbazide have been synthesized and their structures were characterized by elemental analyses, FT-IR, 1H NMR spectroscopy, and X-ray single-crystal diffraction analysis. Molecular orbital calculations have been carried out for 1 and 2 by using an ab initio method (HF) and also density functional method (B3LYP) at 6-31G basis set. Compound 1 crystallizes in the monoclinic system, space group P21/c, with a = 8.1342(5) Å, b = 18.1406(10) Å, c = 8.2847(6) Å, β = 109.7258(17)°, V = 1150.75(12) Å3, and Z = 4, whereas compound 2 crystallizes in the orthorhombic system, space group Pbca, with a = 11.0868(6) Å, b = 13.1332(6) Å, c = 15.9006(8) Å, V = 2315.2(2) Å3, and Z = 8. The compounds 1 and 2 displays a trans-configuration about the C=N double bond. 相似文献
29.
H. Matsumura T. Miura S. Ishihama N. Matsuda T. Aze K. Masumoto T. Suzuki 《Journal of Radioanalytical and Nuclear Chemistry》2007,272(2):423-428
Gold activation detectors were placed at nine positions on the inner wall of the KEK neutrino target station, and were exposed
to secondary particles during approximately one month of machine operation. After exposure, the production rates of 19 spallation
nuclides, which were produced in the Au activation detectors by nuclear reactions with different threshold energies, were
determined by γ-ray spectrometry. Thus, it was indicated that the Au activation detector is a novel tool for obtaining the
distribution of various secondary particles with high intensity and high energy. 相似文献
30.
The persistent spectral hole burning (PSHB) phenomenon was found to occur in many kinds of nanocrystalline semiconductors, such as CdSe, CdS, CuCl, CuBr and CuI, embedded in crystals, glass or polymers. In inhomogeneously broadened exciton absorption spectra of these nanocrystals, the spectral hole and its associated structure were created by the narrow-band laser excitation and were conserved for more than several hours at 2 K. Hole depth grew in proportion to the logarithm of the burning fluence. Thermally-annealing and light-induced hole-filling phenomena were observed. The hole burning takes place by the tunneling process through potential barriers with broadly distributed barrier height and thickness. Unusual luminescence behaviors related to the PSHB phenomena were also observed. They are luminescence elongation with increase of the light exposure and hole burning in the luminescence spectrum. The observed PSHB phenomena are explained by the exciton localization and the succeeding ionization of nanocrystals. The energy of the photoionized nanocrystal is released from the original energy and the new energies depend on the spatial arrangement of the trapped carriers. Quantum confinement of carriers and resulting strong Coulomb interaction between confined carriers and trapped carriers are essential for the energy change. Possible applications of the PSHB phenomenon is discussed. 相似文献