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91.
S. Tanemura K. Kajino L. Miao S. Koide M. Tanemura S. Toh K. Kaneko M. Mori 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2005,34(1-3):79-82
We have succeeded to fabricate the thin film mainly or entirely consisting
of nano-crystallites TiO on a substrate at room temperature by using the
magnetron sputtering combined with the gas aggregation method which has the
capability to deposit grown small particles and/or clusters of the desired
compound material on the substrate in soft-landed mode. The important
experimental parameters to control the growth of TiO particles are
identified as partial pressure of additional oxygen gas, growth-reaction
distance Ltd, and LN2 cooling of growth chamber. The smallest
averaged diameter of TiO nano-particles is 5.62 nm and size distribution
being from 2 to 8 nm under 50 mm of Ltd. The compositional uniformity is
confirmed by EDS and EELS. The chemical state of the film observed by Ti 2P
XPS peak confirms the primarily growth of TiO and indicates the formation of
minor content of amorphous Ti1-xOx and/or Ti1-xCx
particularly at the surface of the film. 相似文献
92.
Polymerization activities of the soluble Ziegler-type of catalyst systems, Ti(OR)4-AlEt3, Ti(NEt2)4-AlMe3, and V(NEt2)4-AlEt3, were investigated. In the catalyst system of Ti(OR)4-AlEt3, formation of two types of Ti(III) compounds, i.e., Ti(OR)2Et and its bridged complex with aluminum alkyl, was confirmed by IR and ESR measurements. With the addition of donor molecule to the system, it was found that the polymer yield decreased remarkably and that the bridged complex dissociated into a single or uncomplex Ti(III) paramagnetic species. It has been concluded that the bridged structure of Ti(III) species was responsible for the polymerization activity of styrene. Two reaction products of Ti(NEt2)3Me and Al(NEt2)Me2 were found by NMR spectroscopic observation with the Ti(NEt2)4-AlMe3 catalyst system. From the kinetic study of polymerization of styrene, it was found that Ti(NEt2)3Me is an active species. An anionic mechanism was proposed for the styrene polymerization by Ti(NEt2)3Me. In the polymerization of MMA with the V(NEt2)4-AlEt3 system, a difference in the tacticity of polymer was found to depend on the polymerization conditions, e.g., AI/V ratio and temperature. From an analysis of the tacticity of the polymer, the presence of two active sites in the propagation process is suggested. 相似文献
93.
Traces of copper ions are sorbed on a cation-exchange resin, and a copper-loaded resin bead is inserted directly into a graphite furnace for atomic absorption spectrometry. The procedure is used for the determination of copper ( > 2 pg ml?1) in tap and various distilled waters. 相似文献
94.
95.
Micro- or nanoelectromechanical system (MEMS/NEMS) is a multidisciplinary field, which has witnessed explosive growth during the past decades. The current materials for MEMS are dominated by Si thanks to the fully based technology for CMOS. However, Si has its own intrinsic limitations such as poor mechanical or tribological properties and poor thermal stability. Carbon-based materials such as diamond, carbon nanotube, and graphene possess excellent properties such as low mass, high Young's modulus, high thermal conductivity, hydrophobic surface, and tailorable electronic configuration, which make these materials promising for MEMS/NEMS applications with diverse and much better performance than Si. In this review, we describe the recent progress of carbon-based materials for MEMS/NEMS with focus on diamond, carbon nanotube, and graphene. The growth of these carbon materials is briefly described and only selected properties are discussed with respect to MEMS/NEMS applications. The fabrication process for suspended structures of these materials toward MEMS/NEMS is comprehensively reviewed from the recent literatures. Special attention is devoted to the state-of-the-art of MEM/NEM switches based on these carbon materials, one of the most important fields in MEMS/NEMS. Finally, the application of carbon-based MEM/NEM switches to microwave field is critically analyzed. 相似文献
96.
Using an AlInN intermediate layer, GaN was grown on (1 1 1)Si substrate by selective metalorganic vapor phase epitaxy. The variation of the surface morphology was investigated as a function of the In composition and thickness of the AlInN layer. It was found that the In composition in the AlInN layer was a function of the growth temperature and thickness. Because of the small band offset at the AlInN/Si hetero-interface, we have achieved a low series resistance of the order of 9 Ω (0.0036 Ω cm2) across the GaN/AlInN/AlN/Si layer structure. 相似文献
97.
The biologically active site of neocarzinostatin-chromophore 总被引:1,自引:0,他引:1
98.
[structure: see text] Symmetrical and unsymmetrical 2',7'-dichlorofluorescein (DCF) derivatives have been synthesized by means of Mannich reactions and an aromatic Claisen rearrangement. NMR and fluorescence spectroscopic studies reveal the correlation between the conformations, the photoinduced electron transfer mechanism, and fluorescent intensities of these DCF derivatives. Two quenching nitrogen atoms cooperatively and reversibly suppress the fluorescence of the chromophore. 相似文献
99.
Dr. Yasuo Tanaka Dr. Tomoki Yoneda Prof. Dr. Ko Furukawa Dr. Taro Koide Hirotaka Mori Dr. Takayuki Tanaka Prof. Dr. Hiroshi Shinokubo Prof. Dr. Atsuhiro Osuka 《Angewandte Chemie (International ed. in English)》2015,54(37):10908-10911
A ZnII‐CuI‐ZnII heterotrimetal complex of decaphyrin was synthesized by stepwise metalations: metalation of a [46]decaphyrin with ZnII ions to produce a 46π decaphyrin bis(ZnII) complex and its subsequent metalation with CuII ion. In the second metalation step, it has been shown that CuII ion is reduced to a CuI ion in the complex and a dianionic bis(ZnII) containing [46]decaphyrin ligand is oxidized to the corresponding monoanionic [45]decaphyrin ligand, indicating a non‐innocent nature of the decaphyrin ligand. Despite the radical nature, the heterotrimetal complex is fairly stable under ambient conditions and exhibits almost no intermolecular magnetic interaction, owing to extensive delocalization of an unpaired electron in the large π‐conjugated circuit of decaphyrin moiety. 相似文献
100.
Fluorescent sensors for specific RNA: a general paradigm using chemistry and combinatorial biology 总被引:1,自引:0,他引:1
Here, we describe a new paradigm for the development of small molecule-based RNA sensors. We prepared a series of potential PET (photoinduced electron transfer) sensors on the basis of 2',7'-dichlorofluorescein (DCF) fluorophore conjugated with two aniline derivatives as electron donors (quenchers). NMR and fluorescent spectroscopic analyses of these DCF derivatives revealed the correlation between the conformations, the PET, and the fluorescent intensities of these DCF derivatives, enabling us to select a sensor candidate. RNA aptamers were raised against the aniline-based quencher via in vitro selection (SELEX). One of these aptamers enhanced the fluorescence intensity of the DCF-aniline conjugate in a concentration-dependent manner. To demonstrate the power and generality of this approach, additional in vitro selection was performed and aptamers from this selection were found to have similar activities. These results show that one can develop fluorescence-inducing reporter RNA and morph it into remotely related sequences without prior structural insight into RNA-ligand binding. 相似文献