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81.
82.
Manabe T Yokoyama K Furukawa S Kachi-Terajima C Nakata K Iwahori F Miyasaka H Sugiura K Yamashita M Kishida H Okamoto H 《Inorganic chemistry》2002,41(20):4993-4995
This communication describes the syntheses of the quasi-one-dimensional mixed-halogen-bridged Ni(III) complexes with strong electron correlation [Ni(chxn)(2)Cl(1-x)Br(x)](NO(3))(2) and the tuning of the spin density wave strengths of these compounds. If the Cl 3p and Br 4p make one band in the compounds, we should observe a single peak in the electronic spectra. As a result, we should observe the single peak from 1.45 to 2.00 eV depending on the mixing ratios of Cl and Br ions. Therefore, the Cl 3p and Br 4p make one band. Then, we have succeeded in tuning the spin density wave strengths of the Ni(III) complexes with the strong electron correlation by mixing the bridging halogen ions successively. 相似文献
83.
Masakazu Tanaka Makoto Oba Naoto Imawaka Yoshitsugu Tanaka Masaaki Kurihara Hiroshi Suemune 《Helvetica chimica acta》2001,84(1):32-46
Heteropentapeptides containing the α‐ethylated α,α‐disubstituted amino acid (S)‐butylethylglycine and four dimethylglycine residues, i.e., CF3CO‐[(S)‐Beg]‐(Aib)4‐OEt ( 4 ) and CF3CO‐(Aib)2‐[(S)‐Beg]‐(Aib)2‐OEt ( 7 ), were synthesized by conventional solution methods. In the solid state, the preferred conformation of 4 was shown to be both a right‐handed (P) and a left‐handed (M) 310‐helical structure, and that of 7 was a right‐handed (P) 310‐helical structure. IR, CD, and 1H‐NMR spectra revealed that the dominant conformation of both 4 and 7 in solution was the 310‐helical structure. These conformations were also supported by molecular‐mechanics calculations. 相似文献
84.
Keiichi Kamada Kouichi Nawashiro Fumiyasu Tamagawa Cha-Yeol Lee Hiroshi Yoshida Sunao Kawasaki Ritoku Ando Masaru Masuzaki 《International Journal of Infrared and Millimeter Waves》2000,21(9):1441-1449
A relativistic electron beam (500 keV, 200 A, 10 ns) generated magnetically tunable microwave radiation in a frequency range of 9-13 GHz when it is injected into an X-band rectangular waveguide immersed in a uniform axial magnetic field (4-10 kG). The mechanism of the microwave radiation was identified as the gyrotron backward wave interaction. The output power of the radiated microwave increased exponentially with the increase of the cavity length. 相似文献
85.
Makoto Oba Nanako Yamagata Mitsunobu Doi Hiroshi Suemune Masaaki Kurihara 《Tetrahedron》2010,66(13):2293-11109
The crystal structures of two diastereomeric -Pro-Pro-(Aib)4- sequences, Cbz-l-Pro-l-Pro-(Aib)4-OMe (1) and Cbz-d-Pro-l-Pro-(Aib)4-OMe (2), have been determined by X-ray crystallographic analysis. The crystals of the two compounds were characterized by the following parameters: (1) monoclinic, P21, a=10.543 Å, b=8.103 Å, c=22.642 Å, β=97.679, Z=2, R1=0.104, and Rw=0.327; (2) orthorhombic, P212121, a=10.470 Å, b=10.953 Å, c=32.405 Å, Z=4, R1=0.040, and Rw=0.046. In the asymmetric unit of 1, the homochiral l-Pro1-l-Pro2 adopts a polyproline II structure, which induces a left-handed (M) 310-helical structure in the following -(Aib)4- sequence. The preferred conformation of diastereomeric 2, which contains heterochiral d-Pro1-l-Pro2 segments, was similar to that of 1 with differences at the N-terminal d-Pro residue. 相似文献
86.
Structural study of 1‐(2′, 3′‐O‐isopropylidene‐(α‐d‐allo and ‐β‐l‐talofuranosyluron)‐5′‐cyanohydrin)uracil stereoisomers by NMR spectroscopy and theoretical methods 下载免费PDF全文
87.
Satoshi Ito Marina Tobata Minenari Asakura Yasutaka Shinozaki Yuuki Iwabe Lisa Sakamoto Shun-pei Ito Makoto Roppongi Toru Oba 《Tetrahedron letters》2017,58(43):4141-4144
Bicyclopyrroles are important synthetic equivalents of isoindoles, which are difficult to synthesize. Using bicyclopyrrole as a starting material, functional organic materials such as benzopyrromethene and benzoporphyrin can be synthesized. However, there are few reports on introducing substituents into bridging positions in bicyclopyrrole. By combining various reactions, we successfully obtained bicyclopyrroles with various substituents at the bridging positions. 相似文献
88.
Tatsuo Taniguchi Fumiyasu Murakami Masakatsu Kasuya Takashi Kojima Michinari Kohri Kyoichi Saito Takayuki Nakahira 《Colloid and polymer science》2013,291(1):215-222
Organic/inorganic hybrids were prepared by catalytic hydrolysis and subsequent polycondensation of tetra-n-butyl titanate (TnBT) in shell layers grafted on core particles. The core particles were synthesized by emulsifier-free emulsion polymerization of styrene, N-n-butyl-N-2-methacryloyloxyethyl-N,N-dimethylammonium bromide (C4DMAEMA), and 2-chloropropionyloxyethyl methacrylate using 2,2′-azobis(2-amidinopropane) dihydrochloride as an initiator. The core diameters were controlled in the range of 70–550 nm by adjusting a C4DMAEMA feed concentration. The core–shell particles were prepared by surface-initiated activator generated electron transfer–atom transfer radical polymerization of 2-(N,N-dimethylamino)ethyl methacrylate (DMAEMA). The sizes of core–shell particles were found to increase monotonically with an increase in a DMAEMA concentration. The hybrid particles were fabricated by adding TnBT into a water/ethanol dispersion of core–shell particles. The amounts of titania deposited increased in proportion to the grafted amounts of poly[2-(N,N-dimethylamino)ethyl methacrylate] on the core particles. The X-ray diffraction measurement revealed that the hollow titania particles obtained by heat treatment of hybrids have an anatase crystallographic phase. 相似文献
89.
90.
Catalytic activation methods of nucleophile precursors recently developed in our research group were reviewed in this paper. These include (i) the catalytic double activation method of nucleophile precursors through enol formation and of electrophiles through coordination in alcohols; (ii) the double catalytic activation method by use of both catalytic amounts of chiral Lewis acid and external achiral amine; (iii) the catalytic activation method of nucleophile precursors with a chiral cationic Lewis acid in the presence of molecular sieves; and (iv) the single catalytic activation of nucleophile precursors through metal enolization in alcohol media. 相似文献