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991.
Suzuki W Fujiwara E Kobayashi A Fujishiro Y Nishibori E Takata M Sakata M Fujiwara H Kobayashi H 《Journal of the American Chemical Society》2003,125(6):1486-1487
Highly conducting crystals based on single-component gold complexes with extended-TTF dithiolate ligands [Au(dmdt)(2)](0+) (1) and [Au(tmdt)(2)](0+) (2) were prepared (dmdt = dimethyltetrathiafulvalenedithiolate and tmdt = trimethylenetetrathiafulvalenedithiolate). On the basis of the synchrotron radiation powder diffraction data, the MEM electron density of 2 was successfully obtained. The conductivities of compacted powder samples of 1 and 2 at room temperature were 12 and 15 S cm(-1), respectively. Pauli-like susceptibility of 1 suggested the system to be essentially metallic at least above 50 K, while 2 showed a magnetic transition around 100 K without loss of its high conductivity. 相似文献
992.
Fumihiko Sakai Hideaki Fujiwara Yoshio Sasaki 《Journal of organometallic chemistry》1986,310(3):293-301
1H T1 and dynamic NMR measurements (T1 = relaxation time) were made with Me2SnCl2 and its bpy complex in mixed solvents of CH2Cl2 and weak bases to elucidate the role of the solvent in the dynamic behaviour of organotin compounds. In the line shape analysis of the exchange reaction between Me2SnCl2 and its bpy complex, the dissociation rate constant kd of the Me2SnCl2 · bpy complex supported an exchange mechanism of the dissociation followed by a rapid recombination step. Weak bases in the mixed solvents decreased the Eyring activation parameters ΔH‡ and ΔS‡ for the dissociation reaction of the complex, indicating more extensive solvation in the activated state than in the ground state of the complex. In the 1H T1 measurements, the reorientational correlation time τc was shorter and its activation energy Ea was larger in Me2SnCl2 than in Me2SnCl2 · bpy, in conformity with their molecular sizes. Ea and τc increased on addition of weak bases, such as nitromethane, nitrobenzene and acetonitrile, even for the Me2SnCl2 · bpy complex, whose acidity is reduced considerably from that of the free tin compound. The major cause of this result is suggested to be the interaction of the weak bases with CH2Cl2, resulting in a change of the physical properties of the mixed solvent. 相似文献
993.
Computer-assisted structure elucidation is improved by the introduction of substructures selected by the user, in addition to analyses of the spectral data of an unknown organic compound. The substructure is called a 'macrocomponent' in the system. The macrocomponent which is input at will is authenticated by comparison with the set of components assembled by the automated analyses of the spectra before it is used for structure construction. It is shown that the introduction of the macrocomponent enhances the correctness and practicality of structure elucidation by computer. 相似文献
994.
Jacques Vicens Takaji Fujiwara Ken-Ichi Tomita 《Journal of inclusion phenomena and macrocyclic chemistry》1988,6(6):577-581
In order to clarify the reason why the stereospecific sulfoxides undergo racemization in solution but not in the complex crystal with -cyclodextrin (-CD) in the solid state, a crystal structure analysis of two -CD inclusion complexes with methyl-p-tolylsulfoxide (MTSO) having a chiral sulfur atom was carried out. 相似文献
995.
Y Kiso M Yoshida T Tatsumi T Kimura Y Fujiwara K Akaji 《Chemical & pharmaceutical bulletin》1989,37(12):3432-3434
We have found that tetrafluoroboric acid (HBF4) in trifluoroacetic acid (TFA) in the presence of thioanisole cleaves various protecting groups currently used in peptide synthesis. HBF4 in TFA cleaves an amino acid amide from 4-methylbenzhydrylamine resin more effectively than trifluoromethanesulfonic acid in TFA. Lamprey gonadotropin-releasing hormone (a 10-residue peptide amide) was synthesized using 1 M HBF4-thioanisole in TFA by both solution-phase and solid-phase methods. 相似文献
996.
We used two-dimensional column chromatography to analyze the composition of a sample of presumably a diblock copolymer of poly(ethylene glycol) (PEG) and poly(L-lactide) synthesized from monomethoxy-terminated PEG. The first dimension of the separation is phase fluctuation chromatography to prepare fractions that contain various components of the copolymer in different ratios. The second dimension is size-exclusion chromatography, NMR, and HPLC at the critical condition of PEG. The PEG initiator has small amounts of diol-terminated dimeric components. We found that the copolymer sample contains a triblock copolymer and low-molecular-mass components in addition to the main part of the diblock copolymer. The SEC chromatograms show that the main part consists of two components with distinct peak lengths for the PLLA block. The low-molecular-mass components have a broad distribution in chemical composition. Phase fluctuation chromatography enriched the triblock copolymer and the diblock copolymer with the longer PLLA block in early fractions when the column was packed with carboxymethyl-modified porous silica. When the porous medium was PLLA-grafted silica, size exclusion dominated, but the low-molecular-mass components were separated according to their chemical composition. 相似文献
997.
Recently, we found that “golf ball”-like polystyrene (PS)/polybutyl acrylate (PBA) composite particles could be produced
by seeded emulsion polymerization of butyl acrylate (BA) with PS seed particles. In this article, the effects of the polymerization
temperature, BA monomer concentration, and the presence of 1-octanol, which is a good solvent for PBA and a poor solvent for
PS in the polymerization, on the morphology was studied.
Received: 25 February 1997 Accepted: 4 October 1997 相似文献
998.
Intense pseudomolecular ions were observed for underivatized, multifunctional compounds of low volatilty (e.g., bile acid conjugates, alkaloids, antibiotics) by employing the direct probe technique of NCI MS; especially effective was the use of CF2CL2 as the reagent gas for producing chloride ion adduct negative ions. 相似文献
999.
Fumio Nishioka Isao Nakanishi Takaji Fujiwara Ken-ichi Tomita 《Journal of inclusion phenomena and macrocyclic chemistry》1984,2(3-4):701-714
The crystal structure of the -cyclodextrin (-CyD) molecular complex with aspirin (acetylsalicylic acid), salicylic acid, and water, (C42H70O35)2 (C9H8O4)2 (C7H6O3) 23.3H2O, was determined by X-ray structure analysis. The crystal data is space group Pl, a=19.777(5), b=15.247(3), c=15.475(4) Å, =102.63(2)°, =116.96(2)°, =104.12(2)°, V=3729(2) Å3, Dm=1.409(2) g/cm3, DX=1.419 g/cm3, and Z=1. The two -CyDs form a dimer unit with hydrogen bond networks among the secondary hydroxyl groups of both -CyDs. This -CyD dimer includes three guest molecules of two different types in its hydrophobic cavity. Two of them are aspirin, which are separately included in each cavity of the -CyD unit, with their hydrophobic benzene rings protruding into the hydrophobic cavities of the host -CyDs. The remaining guest molecule is the hydrolyzed product of an aspirin, that is salicylic acid, which is sandwiched in the space constructed by the -CyD dimer formation, and is statistically disordered at three sites. 相似文献
1000.