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31.
In a given Kähler manifold (M,J) we introduce the notion of Kähler Frenet curves, which is closely related to the complex structure J of M. Using the notion of such curves, we characterize totally geodesic Kähler immersions of M into an ambient Kähler manifold and totally geodesic immersions of M into an ambient real space form of constant sectional curvature . 相似文献
32.
Chisa Higuchi Hiromasa Tanaka Kazunari Yoshizawa 《Journal of computational chemistry》2019,40(1):164-171
The molecular mechanism of the adhesion between silica surface and epoxy resin under atmospheric conditions is investigated by periodic density-functional-theory (DFT) calculations. Slab models of the adhesion interface were built by integrating a fragment of epoxy resin and hydroxylated (0 0 1) surface of α-cristobalite in the presence of adsorbed water molecules. Effects of adsorbed water on the adhesion interaction are evaluated on the basis of geometry-optimized structures, adhesion energies, and forces. Calculated results demonstrate that adsorbed water molecules significantly reduce both the adhesion energies and forces of the silica surface–epoxy resin interface. The reduction of adhesion properties can be associated with structural deformation of water molecules confined in the tight space between the adhesive and adherend as well as structural flexibility of the hydrogen-bonding network in the interfacial region during detachment of the epoxy resin from the hydrophilic silica surface. © 2018 Wiley Periodicals, Inc. 相似文献
33.
Widely tunable terahertz (THz)-wave generation using difference frequency generation (DFG) in an organic N-benzyl-2-methyl-4-nitroaniline (BNA) crystal was demonstrated. To our knowledge, this is the first report of THz-wave generation by BNA DFG. Large, high-quality single crystals of BNA (phi 8 mm x 30 mm) were grown using the vertical Bridgman method. The nonlinear optical (NLO) coefficient d(33) of the BNA crystal is approximately 234 pm/V, which is the largest value reported for any yellow NLO material. The collinear phase-matching condition of the type-0 configuration is satisfied using a 0.7-1 microm band pump wavelength. We generated THz waves using an organic BNA crystal; the generation range is 0.1-15 THz. 相似文献
34.
Hiromasa Nishikiori Rudi Agus Setiawan Kyohei Miyashita Katsuya Teshima Tsuneo Fujii 《Photochemistry and photobiology》2014,90(4):747-759
Fluorescein‐dispersing titania gel films were prepared by the acid‐catalyzed sol–gel reaction using a titanium alkoxide solution containing fluorescein. The molecular forms of fluorescein in the films, depending on its acid–base equilibria, and the complex formation and photoinduced electron transfer process between the dye and titania surface were investigated by fluorescence and photoelectric measurements. The titanium species were coordinated to the carboxylate and phenolate‐like groups of the fluorescein species. The quantum efficiencies of the fluorescence quenching and photoelectric conversion were higher upon excitation of the dianion species interacting with the titania, i.e. the dye–titania complex. This result indicated that the dianion form was the most favorable for formation of the dye–titania complex exhibiting the highest electron transfer efficiency. Using nitric acid as the catalyst, the titania surface bonded to the fluorescein instead of the adsorbed nitrate ion during the steam treatment. The dye–titania complex formation played an important role in the electron injection from the dye to the titania conduction band. 相似文献
35.
Taichi Mitsumoto Dr. Yuya Ashida Dr. Kazuya Arashiba Dr. Shogo Kuriyama Akihito Egi Prof. Dr. Hiromasa Tanaka Prof. Dr. Kazunari Yoshizawa Prof. Dr. Yoshiaki Nishibayashi 《Angewandte Chemie (International ed. in English)》2023,62(43):e202306631
We newly designed and prepared a novel molybdenum complex bearing a 4-[3,5-bis(trifluoromethyl)phenyl]pyridine-based PNP-type pincer ligand, based on the bond dissociation free energies (BDFEs) of the N−H bonds in molybdenum-imide complexes bearing various substituted pyridine-based PNP-type pincer ligands. The complex worked as an excellent catalyst toward ammonia formation from the reaction of an atmospheric pressure of dinitrogen with samarium diiodide as a reductant and water as a proton source under ambient reaction conditions, where up to 3580 equivalents of ammonia were formed based on the molybdenum atom of the catalyst. The catalytic activity was significantly improved by one order of magnitude larger than that observed when using the complex before modification. 相似文献
36.
Inside Cover: Direct Transformation of Molecular Dinitrogen into Ammonia Catalyzed by Cobalt Dinitrogen Complexes Bearing Anionic PNP Pincer Ligands (Angew. Chem. Int. Ed. 46/2016)
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37.
Tomoyuki Miyao Hiromasa Kaneko Kimito Funatsu 《Journal of computer-aided molecular design》2016,30(5):425-446
Generating chemical graphs in silico by combining building blocks is important and fundamental in virtual combinatorial chemistry. A premise in this area is that generated structures should be irredundant as well as exhaustive. In this study, we develop structure generation algorithms regarding combining ring systems as well as atom fragments. The proposed algorithms consist of three parts. First, chemical structures are generated through a canonical construction path. During structure generation, ring systems can be treated as reduced graphs having fewer vertices than those in the original ones. Second, diversified structures are generated by a simple rule-based generation algorithm. Third, the number of structures to be generated can be estimated with adequate accuracy without actual exhaustive generation. The proposed algorithms were implemented in structure generator Molgilla. As a practical application, Molgilla generated chemical structures mimicking rosiglitazone in terms of a two dimensional pharmacophore pattern. The strength of the algorithms lies in simplicity and flexibility. Therefore, they may be applied to various computer programs regarding structure generation by combining building blocks. 相似文献
38.
Direct Transformation of Molecular Dinitrogen into Ammonia Catalyzed by Cobalt Dinitrogen Complexes Bearing Anionic PNP Pincer Ligands
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Dr. Shogo Kuriyama Dr. Kazuya Arashiba Prof. Dr. Hiromasa Tanaka Yuki Matsuo Dr. Kazunari Nakajima Prof. Dr. Kazunari Yoshizawa Prof. Dr. Yoshiaki Nishibayashi 《Angewandte Chemie (International ed. in English)》2016,55(46):14291-14295
The direct formation of ammonia from molecular dinitrogen under mild reaction conditions was achieved by using new cobalt dinitrogen complexes bearing an anionic PNP‐type pincer ligand. Up to 15.9 equivalents of ammonia were produced based on the amount of catalyst together with 1.0 equivalent of hydrazine (17.9 equiv of fixed nitrogen atoms). 相似文献
39.
Nishikiori H Sasai R Takagi K Fujii T 《Langmuir : the ACS journal of surfaces and colloids》2006,22(7):3376-3380
Spironaphthoxazine (SNO) and Zn2+ were intercalated into montmorillonite interlayers hydrophobically modified by the alkyltrimethylammonium cation during UV light irradiation. The fluorescence spectra of the montmorillonite composites were observed to vary with an increase in the UV and visible light irradiation times. These composites exhibited two types of fluorescence emissions: F1, which originates from a new species, Xs, which is different from SNO (ring-closed form) and merocyanine (MC; ring-open form), and F2, which originates from the MC-Zn complex. With increasing UV light irradiation time, the F1 intensities decreased, whereas the F2 intensities increased. Xs, which is an intermediate species between SNO and MC, was transformed into MC and then coordinated with Zn2+ (i.e., MC-Zn complex) during the UV light irradiation. The reaction rate of the formation of the MC-Zn complex decreased for the hydrophobically modified montmorillonite due to a longer alkyl chain. The retrieval changes in the F1 and F2 intensities were observed with an increasing visible light irradiation time, implying the dissociation of the MC-Zn complex into Xs and Zn2+. The dissociation especially occurred for the hydrophobically modified montmorillonite with a longer alkyl chain. The formation and disappearance of Xs and the MC-Zn complex obeyed first-order kinetics, and therefore the interconversion between Xs and MC could be regarded as the rate-determining step of the whole reaction during the UV and visible light irradiations. The photoinduced reactions of the SNO species and Zn2+ were profoundly affected by the physicochemical environment provided by the clay interlayers. It is concluded that the present photoreactions can be controlled not only by the amounts of the intercalated SNO species and Zn2+, but also by the hydrophobic environment created by the surfactant molecules. 相似文献
40.
Shinobu Tsutsui Hiromasa Tanaka Shigeki Matsumoto 《Journal of organometallic chemistry》2006,691(4):595-603
The reduction of p-anisyl(1,2,3-tri-tert-butylcycloprop-2-en-1-yl)dichlorogermane (1) with potassium in the presence of an excess of tert-butyldimethylsilane in benzene under reflux gave p-anisyl(tert-butyldimethylsilyl)(1,2,3-tri-tert-butylcycloprop-2-en-1-yl)germane (4) in 15% yield. The formation of 4 indicates that p-anisyl(1,2,3-tri-tert-butylcycloprop-2-en-1-yl)germylene (2), which is the first example of a (cycloprop-2-en-1-yl)germylene derivative, was generated and trapped by the hydrosilane. The DFT calculations revealed that the cis-2-p-anisyl-1,3,4-tri-tert-butyl-2-germabicyclo[1.1.0]butane-2,4-diyl structure cis-5 is 8.0 kJ/mol more stable than cis-2. The NBO analysis revealed that cis-5 has a 2-germabicyclo[1.1.0]butane diradical character. 相似文献