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61.
Taichi Kusakabe Satoshi Takaishi Tomoyuki Mochida Tat'yana A. Peganova Oleg V. Gusev 《Tetrahedron》2008,64(2):319-327
Oxidative cyclization-carbonylation of 2-alkyl-2-propargylcyclohexane-1,3-diones mediated by Pd(TFA)2/2,2′-isopropylidenebis[(4R)-4-(3,4-dimethoxyphenyl)-2-oxazoline] 28 afforded bicyclic-β-alkoxyacrylates in 51-74% yields with 72-82% ee. The products containing quaternary carbon were converted to optically active hydrindanes 33. 相似文献
62.
Taichi Kano 《Tetrahedron》2008,64(7):1197-1203
The novel pyrrolidine-based amino sulfonamides (R,R)-2, (S)-3, and (S)-4 were designed and synthesized as organocatalysts and successfully applied for the anti-selective direct asymmetric Mannich reaction. 相似文献
63.
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
64.
Hamasaki T Kashiwagi T Imada T Nakamichi N Aramaki S Toh K Morisawa S Shimakoshi H Hisaeda Y Shirahata S 《Langmuir : the ACS journal of surfaces and colloids》2008,24(14):7354-7364
There are few reports on the physiological effects of metal nanoparticles (nps), especially with respect to their functions as scavengers for superoxide anion radical (O2(.-)) and hydroxyl radical (.OH). We tried to detect the scavenging activity of Pt nps using a hypoxanthine-xanthine oxidase system for O2(.-) and using a Fenton and a UV/H2O2 system for .OH. Electron spin resonance analysis revealed that 2 nm particle size Pt nps have the ability to scavenge O2(.-) and .OH. The calculated rate constant for the O2(.-)-scavenging reaction was 5.03 +/- 0.03 x 10(7) M (-1) s (-1). However, the analysis of the Fenton and UV/H 2O 2 system in the presence of Pt nps suggested that the .OH-scavenging reaction cannot be determined in both systems. Among particle sizes tested from 1 to 5 nm, 1 nm Pt nps showed the highest O2(.-)-scavenging ability. Almost no cytotoxicity was observed even after adherent cells (TIG-1, HeLa, HepG2, WI-38, and MRC-5) were exposed to Pt nps at concentrations as high as 50 mg/L. Pt nps scavenged intrinsically generated reactive oxygen species (ROS) in HeLa cells. Additionally, Pt nps significantly reduced the levels of intracellular O2(.-) generated by UVA irradiation and subsequently protected HeLa cells from ROS damage-induced cell death. These findings suggest that Pt nps may be a new type of antioxidant capable of circumventing the paradoxical effects of conventional antioxidants. 相似文献
65.
Mohammed A. Sanhoob Oki Muraza Teruoki Tago Taichi Taniguchi Gaku Watanabe Takao Masuda 《Research on Chemical Intermediates》2016,42(7):6437-6448
Desilicated MTW zeolite was evaluated in methylation of 2-methylnaphthalene (2-MN) in a fixed-bed flow reactor at 450 °C. Mesoporous MTW was fabricated via a microwave-assisted desilication process using a harsh alkaline solution to improve the pore volume and the surface area. H-ZSM-12 zeolite was treated with 0.3 M of NaOH solution with different treatment times. Due to the harsh alkaline treatment, micropores were blocked by the deposition of the removed atoms. Due to the importance of methylnaphthalenes intermediates, modified MTW zeolites were evaluated in methylation of 2-MN. Methanol (MeOH), 2-MN and 1,3,5-trimethylbenzene (TMB) were fed to the reactor with a molar ratio of 15:15:70. Higher selectivity to 1-methylnaphthalene (1-MN) was observed rather than dimethylnaphthalene and trimethylnaphthalene with a yield of 13.6, 8 and 2.5 mol%, respectively. Moderate conversion up to 24.1 mol% was reached for 30 min reaction. 相似文献
66.
[reaction: see text] A guest molecule-a bis-N-tetraethyleneglycol-substituted 3,3'-difluorobenzidine derivative-has been synthesized, and its complexation with the host, cyclobis(paraquat-p-phenylene), has been investigated. This host-guest complex was then employed in the template-directed synthesis of a blue-colored [2]rotaxane. The color of this [2]rotaxane arises from the charge-transfer absorption band between the HOMO of the guest and the LUMO of the host. This host-guest complex, and the derived [2]rotaxane, completes the donor-acceptor-based RGB (red/green/blue) color complex set. 相似文献
67.
A probabilistic model of a flow of fluid through a random medium,percolation model, provides a typical example of statistical mechanical problems which are easy to describe but difficult to solve. While the percolation problem on undirected planar lattices is exactly solved as a limit of the Potts models, there still has been no exact solution for the directed lattices. The most reliable method to provide good approximations is a numerical estimation using finite power-series expansion data of the infinite formal power series for percolation probability. In order to calculate higher-order terms in power series, Baxter and Guttmann [6] and Jensen and Guttmann [33] proposed an extrapolation procedure based on an assumption that thecorrection terms, which show the difference between the exact infinite power series and approximate finite series, are expressed as linear combinations of the Catalan numbers.In this paper, starting from a brief review on the directed percolation problem and the observation by Baxter, Guttmann, and Jensen, we state some theorems in which we explain the reason why the combinatorial numbers appear in the correction terms of power series. In the proof of our theorems, we show several useful combinatorial identities for the ballot numbers, which become the Catalan numbers in a special case. These identities ensure that a summation of products of the ballot numbers with polynomial coefficients can be expanded using the ballot numbers. There is still a gap between our theorems and the Baxter-Guttmann-Jensen observation, and we also give some conjectures.As a generalization of the percolation problem on a directed planar lattice, we present two topics at the end of this paper: The friendly walker problem and the stochastic cellular automata in higher dimensions. We hope that these two topics as well as the directed percolation problem will be of much interest to researchers of combinatorics. 相似文献
68.
Dr. Fenghua Ding Atsunori Doi Dr. Takafumi Ogawa Dr. Hiroki Ubukata Dr. Tong Zhu Dr. Daichi Kato Dr. Cédric Tassel Dr. Itaru Oikawa Dr. Naoki Inui Dr. Satoru Kuze Tsutomu Yamabayashi Dr. Kotaro Fujii Prof. Masatomo Yashima Prof. Xing Ou Dr. Zhijian Wang Prof. Xiaobo Min Prof. Koji Fujita Prof. Hitoshi Takamura Prof. Akihide Kuwabara Tianren Zhang Prof. Kent J. Griffith Prof. Zhang Lin Prof. Liyuan Chai Prof. Hiroshi Kageyama 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2024,136(15):e202401779
The Li3MX6 compounds (M=Sc, Y, In; X=Cl, Br) are known as promising ionic conductors due to their compatibility with typical metal oxide cathode materials. In this study, we have successfully synthesized γ-Li3ScCl6 using high pressure for the first time in this family. Structural analysis revealed that the high-pressure polymorph crystallizes in the polar and chiral space group P63mc with hexagonal close-packing (hcp) of anions, unlike the ambient-pressure α-Li3ScCl6 and its spinel analog with cubic closed packing (ccp) of anions. Investigation of the known Li3MX6 family further revealed that the cation/anion radius ratio, rM/rX, is the factor that determines which anion sublattice is formed and that in γ-Li3ScCl6, the difference in compressibility between Sc and Cl exceeds the ccp rM/rX threshold under pressure, enabling the ccp-to-hcp conversion. Electrochemical tests of γ-Li3ScCl6 demonstrate improved electrochemical reduction stability. These findings open up new avenues and design principles for lithium solid electrolytes, enabling routes for materials exploration and tuning electrochemical stability without compositional changes or the use of coatings. 相似文献
69.
70.
Xiong DB Okamoto NL Waki T Zhao Y Kishida K Inui H 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(9):2536-2542
Heusler phases, including the full- and half-Heusler families, represent an outstanding class of multifunctional materials on account of their great tunability in compositions, valence electron counts (VEC), and properties. Here we demonstrate a systematic design of a series of new compounds with a 2×2×2 superstructure of the half-Heusler unit cell in X-Y-Z (X=Fe, Ru, Co, Rh, Ir; Y=Zn, Mn; Z=Sn, Sb) systems. Their structures were solved by using both powder and single-crystal X-ray diffraction, and also directly observed by using high-angle annular dark-field imaging in a scanning transmission electron microscope (HAADF-STEM). The VEC values of these new compounds span a wide and continuous range comparable to those for the full- and half-Heusler families, thereby implying tunability in compositions and physical properties in the superstructure. In fact, we observed abnormal electrical properties and a ferromagnetic semiconductor-like behavior with a high and tunable Curie temperature in these superstructures. 相似文献